Image forming apparatus and processing cartridge

Abstract

The present invention relates to an image forming device and a process cartridge. The image forming device includes an image holder, a latent image forming mechanism, a developing mechanism, a transfer mechanism, and a cleaning mechanism. The cleaning mechanism includes a mechanism A or a mechanism B. The mechanism A includes a cleaning blade that contacts the surface of the image holder, and the JIS-A hardness of the cleaning blade at a portion contacting the image holder is 90 degrees or greater. The mechanism B includes a cleaning blade that contacts the surface of the image holder, and the contact load of the cleaning blade with the image holder is controlled by a constant load method. A toner for electrostatic image development includes toner particles and silica particles, and the silica particles have a number average particle size of 110 nm or more and 130 nm or less, a large diameter side number particle size distribution index (upper GSDp) of less than 1.080, an average circularity of 0.94 or more and 0.98 or less, and a proportion of particles with a circularity of 0.92 or more that is 80% by number or more.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus and a process cartridge. Background Art

[0002] Methods of visualizing image information via electrostatic images, such as electrophotography, are currently used in various fields.

[0003] In the past, in electronic photography, a method of visualization is generally used that goes through the following two or more steps: using various mechanisms to form an electrostatic latent image on a photoreceptor or an electrostatic recording body, causing electrostatic particles called toner to adhere to the electrostatic latent image to develop the electrostatic latent image (toner image), transfer it to the surface of the transfer body, and fix it by heating, etc.

[0004] Furthermore, as a conventional cleaning device, the cleaning device described in Japanese Patent Application Laid-Open No. 2011-221437 is known.

[0005] Japanese Patent Gazette No. 2011-221437 discloses a cleaning device, characterized in that it has an image retaining body, a rotating part and a load applying mechanism, the rotating part comprising: a cleaning scraper that abuts in the opposite direction relative to the rotation direction of the above-mentioned image retaining body; a cleaning scraper supporting component that holds the above-mentioned cleaning scraper and rotates with a rotating fulcrum as an axis; and a counterweight component fixedly installed relative to the above-mentioned cleaning scraper supporting component, for causing the above-mentioned cleaning scraper to apply a certain load in the direction of abutment with the above-mentioned image retaining body. In the load applying mechanism, when the above-mentioned cleaning scraper is in abutment with the above-mentioned image retaining body, when the above-mentioned image retaining body rotates to cause the above-mentioned rotating part to rotate in the same direction (anti-kawuta direction), the above-mentioned cleaning scraper applies a load in the direction of abutment with the above-mentioned image retaining body.

[0006] Furthermore, as a conventional image forming method, the method described in Japanese Patent Application Laid-Open No. 2006-259311 is known.

[0007] Japanese Patent Gazette No. 2006-259311 discloses an image forming method, which is an electronic photographic image forming method having at least the steps of charging, image exposure, development, transfer, fixing and cleaning a photoreceptor to form a toner image, characterized in that the step of performing the above-mentioned cleaning treatment is a scraper cleaning method in which a cleaning scraper is brought into contact with the above-mentioned photoreceptor to remove the transfer residual toner on the photoreceptor, the rebound resilience of the above-mentioned cleaning scraper at 23°C is 50% or more, the contact pressure of the above-mentioned cleaning scraper relative to the above-mentioned photoreceptor is 0.20 to 0.70 N / cm, an external additive is added to the above-mentioned toner for use, the primary particles of the above-mentioned external additive have a number average particle size of 20 to 100 nm, and contain particles with particle sizes of 10 to 20 nm and 200 to 300 nm, and the roundness of the above-mentioned toner is 0.94 or more. Summary of the Invention

[0008] Technical problem to be solved by the invention

[0009] The technical problem to be solved by the present invention is to provide an image forming device, in which, in an image forming device having a cleaning mechanism as the mechanism A or the mechanism B described later, the image defect suppression property in the obtained image is excellent compared with the case where the external additive in the toner for electrostatic image development is silica particles having a number average particle size of less than 110 nm or greater than 130 nm, or a large diameter side number particle size distribution index (upper side GSDp) of 1.080 or greater, or an average circularity of less than 0.94 or greater than 0.98, or a proportion of circularity of 0.92 or greater than less than 80% by number.

[0010] Means for solving technical problems

[0011] According to a first embodiment of the present invention, an image forming apparatus is provided, which comprises: an image holder; a latent image forming mechanism for forming an electrostatic latent image on the image holder; a developing mechanism for storing an electrostatic image developer containing a toner for electrostatic image development and developing the electrostatic latent image formed on the surface of the image holder into a toner image for electrostatic image development using the electrostatic image developer; a transferring mechanism for transferring the toner image to a recording medium; and a cleaning mechanism for removing residual toner on the image holder, the cleaning mechanism comprising a mechanism A or a mechanism B, the mechanism A comprising a cleaning blade in contact with the surface of the image holder, The JIS-A hardness of the abutment portion of the cleaning scraper with the image retainer is greater than 90 degrees, mechanism B includes a cleaning scraper in contact with the surface of the image retainer, and the abutment load of the cleaning scraper with the image retainer is controlled by a constant load method. The toner for electrostatic image development contains toner particles and silica particles, and the number average particle size of the silica particles is greater than 110 nm and less than 130 nm, the number particle size distribution index on the large diameter side (upper side GSDp) is less than 1.080, the average roundness is greater than 0.94 and less than 0.98, and the proportion of roundness greater than 0.92 is greater than 80% by number.

[0012] According to the second aspect of the present invention, the large-diameter side number size distribution index (upper GSDp) of the silica particles is less than 1.075.

[0013] According to the third aspect of the present invention, the silica particles have a smaller diameter side number size distribution index (lower GSDp) of less than 1.080.

[0014] According to a fourth aspect of the present invention, the average circularity of the silica particles is 0.95 or more and 0.97 or less.

[0015] According to a fifth aspect of the present invention, the cleaning blade is a laminated blade.

[0016] According to a sixth aspect of the present invention, the cleaning blade includes a layer having a JIS-A hardness of 90 degrees or higher and a layer having a lower hardness than the layer having a JIS-A hardness of 90 degrees or higher.

[0017] According to the seventh aspect of the present invention, in the cleaning blade, the difference in hardness between the layer having a JIS-A hardness of 90 degrees or more and the layer having a lower hardness is 15 degrees or more in JIS-A hardness.

[0018] According to an eighth aspect of the present invention, the cleaning blade having a JIS-A hardness of 90 degrees or higher at the contact portion is a cleaning blade in which the contact portion is subjected to a curing treatment.

[0019] According to a ninth aspect of the present invention, among the silica particles, the proportion of particles having a circularity of 0.92 or greater is 85% by number or greater.

[0020] According to a tenth aspect of the present invention, the electrostatic image developing toner further contains inorganic oxide particles having a number average particle size of 5 nm to 50 nm.

[0021] According to the eleventh aspect of the present invention, the ratio (Da / Db) of the number average particle diameter Da of the silica particles to the number average particle diameter Db of the inorganic oxide particles is 2.5 to 20.

[0022] According to a twelfth aspect of the present invention, the toner particles contain a styrene acrylic resin as a binder resin.

[0023] According to a thirteenth aspect of the present invention, the toner particles contain an amorphous polyester resin as a binder resin.

[0024] According to a 14th aspect of the present invention, there is provided a process cartridge to be loaded and unloaded in an image forming apparatus, comprising: a developing mechanism for storing an electrostatic image developer containing an electrostatic image developing toner and developing an electrostatic latent image formed on a surface of an image retaining member into an electrostatic image developing toner image using the electrostatic image developer; and a cleaning mechanism for removing residual toner on the image retaining member, the cleaning mechanism comprising a mechanism A or a mechanism B, the mechanism A comprising a cleaning blade in contact with the surface of the image retaining member, a portion of the cleaning blade in contact with the image retaining member being provided with a cleaning blade. The S-A hardness is greater than 90 degrees, the mechanism B has a cleaning scraper in contact with the surface of the above-mentioned image retaining body, the contact load of the above-mentioned cleaning scraper with the above-mentioned image retaining body is controlled by a constant load method, the above-mentioned electrostatic image developing toner contains toner particles and silica particles, the number average particle size of the silica particles is greater than 110nm and less than 130nm, the number particle size distribution index on the large diameter side (upper side GSDp) is less than 1.080, the average roundness is greater than 0.94 and less than 0.98, and the proportion of roundness greater than 0.92 is greater than 80% by number.

[0025] Effects of the Invention

[0026] According to the above-mentioned scheme 1, 12 or 13, an image forming device is provided, in which, in an image forming device having a cleaning mechanism as the above-mentioned mechanism A or mechanism B, the image defect suppression property in the obtained image is excellent compared with the case where the external additive in the toner for electrostatic image development is silica particles having a number average particle size of less than 110 nm or greater than 130 nm, or a large diameter side number particle size distribution index (upper side GSDp) of 1.080 or greater, or an average roundness of less than 0.94 or greater than 0.98, or a proportion of roundness of 0.92 or greater is less than 80% by number.

[0027] According to the second aspect, there is provided an image forming apparatus capable of obtaining an image with improved image defect suppression compared to a case where the large-diameter side number size distribution index (upper GSDp) of the silica particles is 1.075 or greater.

[0028] According to the third aspect, there is provided an image forming apparatus capable of obtaining an image with improved image defect suppression compared to a case where the silica particles have a smaller diameter side number size distribution index (lower GSDp) of 1.080 or greater.

[0029] According to the fourth aspect, there is provided an image forming apparatus capable of obtaining an image with better image defect suppression performance than when the average circularity of the silica particles is less than 0.95 or greater than 0.97.

[0030] According to the fifth or eighth aspect, there is provided an image forming apparatus capable of obtaining an image with better image defect suppression performance than when the cleaning blade is a single-layer blade.

[0031] According to the sixth aspect, there is provided an image forming apparatus capable of obtaining an image with better image defect suppression performance than when the cleaning blade is a laminated blade including only a layer having a JIS-A hardness of less than 90 degrees.

[0032] According to the above-mentioned seventh scheme, an image forming device is provided, in which the image defect suppression property in the obtained image is better than that in the case where the difference in hardness between the layer with a JIS-A hardness of 90 degrees or more and the layer with low hardness in the above-mentioned cleaning blade is less than 15 degrees in JIS-A hardness.

[0033] According to the ninth aspect, there is provided an image forming apparatus capable of obtaining an image with improved image defect suppression compared to a case where the proportion of particles having a circularity of 0.92 or greater in the silica particles is less than 85% by number.

[0034] According to the tenth aspect, there is provided an image forming apparatus capable of obtaining an image with improved image defect suppression compared to a case where the external additive in the electrostatic image developing toner is solely the silica particles.

[0035] According to the above-mentioned scheme 11, an image forming device is provided, in which the image defect suppression property in the obtained image is better than that in the case where the ratio (Da / Db) of the number average particle size Da of the above-mentioned silica particles to the number average particle size Db of the above-mentioned inorganic oxide particles is less than 2.5 or greater than 20.

[0036] According to the above-mentioned 14th scheme, a processing box is provided, and the image defect suppression property in the image obtained by the processing box of the 14th scheme is excellent compared with the case where the external additive in the electrostatic image developing toner in the processing box having the cleaning mechanism as the above-mentioned mechanism A or mechanism B is silica particles having a number average particle size of less than 110nm or greater than 130nm, or a large diameter side number particle size distribution index (upper side GSDp) of 1.080 or greater, or an average circularity of less than 0.94 or greater than 0.98, or a proportion of circularity of 0.92 or greater than less than 80% by number. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0038] Figure 2 This is a schematic cross-sectional view showing an example of the layer structure of the image holding member in the image forming apparatus according to the present embodiment.

[0039] Figure 3 This is a schematic cross-sectional view showing another example of the layer structure of the image holding member in the image forming apparatus according to the present embodiment.

[0040] Figure 4 It will Figure 1 An enlarged view showing an enlarged view of a position where a cleaning blade contacts an image holding member in an image forming apparatus.

[0041] Figure 5 This is a schematic cross-sectional view showing an example of a mechanism B used in the image forming apparatus according to this embodiment. DETAILED DESCRIPTION

[0042] In the numerical range described in stages in the present invention, the upper limit or lower limit described in one numerical range can be replaced by the upper limit or lower limit of the numerical range in other stages described. In addition, in the numerical range described in the present invention, the upper limit or lower limit of the numerical range can be replaced by the value shown in the embodiments.

[0043] In this specification, when referring to the amount of each component in a composition, if two or more substances corresponding to each component are present in the composition, unless otherwise specified, the amount refers to the total amount of the two or more substances present in the composition.

[0044] In this specification, “toner for developing electrostatic images” is also simply referred to as “toner”, and “developer for developing electrostatic images” is also simply referred to as “developer”.

[0045] Hereinafter, an embodiment as an example of the present invention will be described.

[0046] <Image Forming Apparatus>

[0047] The image forming apparatus of this embodiment comprises: an image holder; a latent image forming mechanism for forming an electrostatic latent image on the image holder; a developing mechanism for storing an electrostatic image developer containing a toner for electrostatic image development and developing the electrostatic latent image formed on the surface of the image holder into a toner image for electrostatic image development using the electrostatic image developer; a transferring mechanism for transferring the toner image to a recording medium; and a cleaning mechanism for removing residual toner on the image holder, wherein the cleaning mechanism comprises a mechanism A or a mechanism B, wherein the mechanism A comprises a cleaning blade in contact with the surface of the image holder, wherein the cleaning blade The JIS-A hardness of the contact portion with the above-mentioned image retainer is greater than 90 degrees, and the mechanism B has a cleaning scraper that contacts the surface of the above-mentioned image retainer. The mechanism B controls the contact load of the above-mentioned cleaning scraper with the above-mentioned image retainer by a constant load method. The above-mentioned toner for electrostatic image development contains toner particles and silica particles, and the number average particle size of the silica particles is greater than or equal to 110 nm and less than or equal to 130 nm, the number particle size distribution index on the large diameter side (upper side GSDp) is less than 1.080, the average roundness is greater than or equal to 0.94 and less than or equal to 0.98, and the proportion of particles with a roundness of greater than or equal to 0.92 is greater than or equal to 80% by number.

[0048] In an image forming apparatus adopting a blade cleaning method, a scraping force and stability of the blade posture are required at the contact portion between the cleaning blade and the image holding member.

[0049] By using the cleaning mechanism as the mechanism A or the mechanism B, the scraping force of the contact portion between the cleaning blade and the image holding member and the stability of the blade posture are excellent.

[0050] However, in an imaging device having a cleaning mechanism serving as the above-mentioned mechanism A or the above-mentioned mechanism B, when an existing toner to which a small-particle external additive is added is used to output images at a low image density for a long time under a high-temperature and high-humidity environment, the external additive is buried in the toner particles, the amount of the external additive supplied to the above-mentioned abutment portion is reduced, the friction coefficient between the image retaining body and the cleaning scraper increases, the cleaning scraper is worn, the cleaning performance is reduced, and image defects such as whitening of the image occur.

[0051] On the other hand, in an imaging device having a cleaning mechanism serving as the above-mentioned mechanism A or the above-mentioned mechanism B, when an existing colorant to which a large-particle external additive is added is used and image output is performed at a high image density for a long time under a low-temperature and low-humidity environment, the amount of the external additive supplied to the above-mentioned abutment portion increases, leakage of the external additive occurs, the cleaning scraper is damaged, and image defects occur.

[0052] It can be inferred that in the image forming device of this embodiment, by using the above-mentioned silica particles with specific physical property values as an external additive for the electrostatic image developing toner, the rolling action of the above-mentioned silica particles is moderate, which can reduce the wear of the cleaning scraper and reduce the leakage of the external additive, thereby suppressing the wear and damage of the cleaning scraper and suppressing image defects in the obtained image.

[0053] Next, the configuration of the image forming apparatus according to this embodiment will be described in detail.

[0054] The image forming device of this embodiment includes: an image retainer, a latent image forming mechanism for forming an electrostatic latent image on the above-mentioned image retainer, a developing mechanism for developing the above-mentioned electrostatic latent image using a toner to form a toner image, a transfer mechanism for transferring the above-mentioned toner image to a recording medium, and a cleaning mechanism for removing residual toner on the above-mentioned image retainer; the above-mentioned cleaning mechanism includes mechanism A or mechanism B, mechanism A has a cleaning scraper in contact with the surface of the above-mentioned image retainer, and the JIS-A hardness of the abutment portion of the above-mentioned cleaning scraper with the above-mentioned image retainer is greater than 90 degrees, and mechanism B has a cleaning scraper in contact with the surface of the above-mentioned image retainer, and mechanism B controls the abutment load of the above-mentioned cleaning scraper with the above-mentioned image retainer by a constant load method.

[0055] The image forming device of this embodiment is suitable for the following well-known image forming devices: a device using a direct transfer method for directly transferring a color electrostatic image developing toner image formed on the surface of an image holder to a recording medium; a device using an intermediate transfer method for transferring a color electrostatic image developing toner image formed on the surface of an image holder to the surface of an intermediate transfer body for the first time, and for transferring the electrostatic image developing toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium for the second time; a device having a cleaning mechanism for cleaning the surface of an image holder after the toner image is transferred and before charging; a device having a static elimination mechanism for eliminating static by irradiating the surface of an image holder with static elimination light after the toner image for electrostatic image development is transferred and before charging; and the like.

[0056] In the case of an intermediate transfer device, the transfer mechanism is, for example, composed of the following components: an intermediate transfer body to the surface of which the electrostatic image developing toner image is transferred; a primary transfer mechanism that transfers the electrostatic image developing toner image formed on the surface of the image retaining body to the surface of the intermediate transfer body for the first time; and a secondary transfer mechanism that transfers the electrostatic image developing toner image transferred to the surface of the intermediate transfer body for the second time to the surface of the recording medium.

[0057] In the image forming apparatus of the present embodiment, for example, at least a portion including the image holding member may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus.

[0058] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. It should be noted that the main parts shown in the drawings will be described, and the other parts will be omitted.

[0059] Figure 1 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0060] like Figure 1 As shown, for example, an image holder (electrophotographic photoreceptor) 12 is provided in the image forming apparatus 10 of this embodiment. The image holder 12 is cylindrical and is connected to a drive unit 27 such as a motor via a driving force transmission member such as a gear (not shown). The drive unit 27 is driven to rotate about a rotation axis indicated by a black dot. Figure 1 In the example shown, the motor is driven to rotate in the direction of arrow A.

[0061] For example, the charging mechanism 15, the latent image forming mechanism 16, the developing mechanism 18, the transfer mechanism 31, the cleaning mechanism 22, and the neutralization mechanism 24 are sequentially arranged around the image holder 12 along the rotation direction of the image holder 12. Furthermore, the fixing mechanism 26 having a fixing member 26A and a pressure member 26B arranged in contact with the fixing member 26A is also provided in the image forming apparatus 10. Furthermore, the image forming apparatus 10 includes a control mechanism 36 for controlling the operation of each mechanism (each unit). It should be noted that the unit including the image holder 12, the charging mechanism 15, the latent image forming mechanism 16, the developing mechanism 18, the transfer mechanism 31, and the cleaning mechanism 22 corresponds to the image forming unit.

[0062] The image forming apparatus 10 includes at least a process cartridge in which an image holding member 12 is integrated with other devices.

[0063] The following describes in detail each mechanism (each unit) of the image forming apparatus 10 .

[0064] [Image holding body]

[0065] The image holding member in the image forming apparatus of this embodiment preferably includes a photosensitive layer on a conductive substrate and may further include a surface protective layer on the photosensitive layer.

[0066] The photosensitive layer may be a single-layer photosensitive layer containing a charge generating material and a charge transporting material in the same photosensitive layer, integrating their functions, or a laminated photosensitive layer having separate functions of a charge generating layer and a charge transporting layer. In the case of a laminated photosensitive layer, the order of the charge generating layer and the charge transporting layer is not particularly limited. Preferably, the image holder has a configuration comprising a charge generating layer, a charge transporting layer, and a surface protective layer in this order on a conductive substrate. Furthermore, the image holder may further comprise layers other than these.

[0067] Figure 2 This is a schematic cross-sectional view illustrating an example of the layer structure of an image holder in the image forming apparatus of this embodiment. Image holder 107A has a structure in which an undercoat layer 101 is provided on a conductive substrate 104, and a charge generation layer 102, a charge transport layer 103, and a surface protective layer 106 are formed thereon in this order. Image holder 107A includes a photosensitive layer 105 whose functions are separated into the charge generation layer 102 and the charge transport layer 103.

[0068] in addition, Figure 3 This is a schematic cross-sectional view showing another example of the layer structure of the image holding member in the image forming apparatus according to the present embodiment. Figure 3The image support member 107B shown has a structure in which a primer layer 101 is provided on a conductive substrate 104, a photosensitive layer 105, and a surface protective layer 106 are sequentially formed. In the image support member 107B, a charge generating material and a charge transporting material are contained in the same photosensitive layer 105, forming a single-layer photosensitive layer with integrated functions.

[0069] It should be noted that the image holding member in this embodiment may or may not be provided with the primer layer 101 .

[0070] The image holding member in this embodiment will be described below in detail, but reference numerals will be omitted for description.

[0071] (Conductive substrate)

[0072] Examples of the conductive substrate include metal plates, metal cylinders, and metal belts made of metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Examples of the conductive substrate include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" means a volume resistivity of less than 10 13 Ωcm.

[0073] When the image holder is used in a laser printer, the surface of the conductive substrate is preferably roughened to a centerline average roughness Ra of 0.04 μm to 0.5 μm to suppress interference fringes generated when irradiated with laser light. While roughening to prevent interference fringes is not particularly necessary when using non-interference light as the light source, it is more effective in achieving a longer lifespan because it can suppress defects caused by uneven surfaces on the conductive substrate.

[0074] Examples of roughening methods include wet honing in which an abrasive is suspended in water and sprayed onto a support; centerless grinding in which a conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0075] As a method for roughening the surface, the following method can be cited: instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened using particles dispersed in the layer.

[0076] In the roughening treatment of anodic oxidation, an oxide film is formed on the surface of the conductive substrate by carrying out anodic oxidation in an electrolyte solution using a conductive substrate made of metal (such as aluminum) as an anode. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be enumerated. However, the porous anodic oxide film formed by anodic oxidation is a chemically active film in its original state, easily contaminated, and the resistance change due to the environment is also larger. Therefore, for the porous anodic oxide film, it is preferably carried out following sealing treatment: hydration reaction is carried out in pressurized steam or boiling water (metal salts such as nickel can be added), and the hydration reaction causes volume expansion, thereby sealing the micropores of the oxide film and becoming a more stable hydrated oxide.

[0077] The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. When the film thickness is within the above range, it tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential due to repeated use.

[0078] The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.

[0079] The treatment using an acidic treatment solution can be implemented, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. Regarding the mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution, for example, phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is in the range of 0.5% by mass to 2% by mass. The overall concentration of these acids can be in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the coating is preferably 0.3μm to 15μm.

[0080] The boehmite treatment is preferably performed by, for example, immersing the substrate in pure water at 90°C to 100°C for 5 to 60 minutes, or contacting the substrate with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. The substrate may further be anodized using an electrolyte solution with low film solubility, such as adipic acid, boric acid, a borate, a phosphate, a phthalate, a maleate, a benzoate, a tartrate, or a citrate.

[0081] (Base coating)

[0082] The undercoat layer is, for example, a layer containing inorganic particles and a binding resin.

[0083] Examples of inorganic particles include particles with a powder resistance (volume resistivity) of 10 2 Ωcm or more 10 11Among these, examples of inorganic particles having the above resistance value include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, and zinc oxide particles are particularly preferred.

[0084] The specific surface area of the inorganic particles based on the BET method is preferably 10 m 2 / g or above.

[0085] The volume average particle size of the inorganic particles is preferably, for example, 50 nm to 2,000 nm (more preferably 60 nm to 1,000 nm).

[0086] The content of the inorganic particles is, for example, preferably from 10% by mass to 80% by mass, and more preferably from 40% by mass to 80% by mass, based on the binder resin.

[0087] The inorganic particles may be surface-treated. Two or more inorganic particles having different surface treatments or different particle sizes may be mixed and used.

[0088] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0089] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0090] Silane coupling agents can be used in combination of two or more. For example, a silane coupling agent having an amino group can be used in combination with other silane coupling agents. Examples of such other silane coupling agents include vinyl trimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane, but are not limited thereto.

[0091] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0092] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0093] Here, from the viewpoint of long-term stability of electrical characteristics and high carrier-blocking properties, the undercoat layer may contain an electron-accepting compound (acceptor compound) together with the inorganic particles.

[0094] As electron-accepting compounds, for example, the following electron-transporting substances can be cited: quinone compounds such as chloranil and bromoquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenoquinone; and the like.

[0095] In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferable.

[0096] Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specific examples include anthraquinone, alizarin, quinizarin, anthraquinone, and purpurin.

[0097] The electron-accepting compound may be dispersed in the undercoat layer together with the inorganic particles, or may be contained in the undercoat layer in a state of being attached to the surfaces of the inorganic particles.

[0098] Examples of a method for attaching the electron-accepting compound to the surface of the inorganic particles include a dry method and a wet method.

[0099] The dry method is, for example, a method in which inorganic particles are stirred using a mixer having a large shear force, while an electron-accepting compound is added dropwise directly or dissolved in an organic solvent, or sprayed with dry air or nitrogen, so that the electron-accepting compound adheres to the surface of the inorganic particles. When the electron-accepting compound is added dropwise or sprayed, it is preferably done at a temperature below the boiling point of the solvent. After the electron-accepting compound is added dropwise or sprayed, it can be further calcined at 100°C or above. There is no particular restriction on the calcination temperature and time as long as the calcination temperature and time are such that electrophotographic properties can be obtained.

[0100] The wet method is, for example, the following method: while dispersing the inorganic particles in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., an electron-accepting compound is added, and the solvent is removed after stirring or dispersion to allow the electron-accepting compound to adhere to the surface of the inorganic particles. As for the solvent removal method, for example, distillation removal is performed by filtration or distillation. After the solvent is removed, calcination can be further performed at a temperature of 100°C or above. There is no particular limitation on the calcination temperature and time as long as the calcination temperature and time are such that electronic photographic characteristics can be obtained. In the wet method, the water contained in the inorganic particles can be removed before the electron-accepting compound is added. As examples thereof, a method of removing the water while heating and stirring in a solvent and a method of removing the water by azeotropic reaction with the solvent can be cited.

[0101] The electron-accepting compound may be attached before or after the inorganic particles are surface-treated with a surface treatment agent, or the electron-accepting compound may be attached and the surface treatment with a surface treatment agent may be performed simultaneously.

[0102] The content of the electron-accepting compound is preferably from 0.01% by mass to 20% by mass, and more preferably from 0.01% by mass to 10% by mass, relative to the total mass of the inorganic particles.

[0103] Examples of the adhesive resin used in the primer layer include the following well-known materials: acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, epoxy resins, and other well-known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; silane coupling agents, and the like.

[0104] As the binding resin used in the primer layer, for example, charge transport resins having charge transport groups, conductive resins (such as polyaniline, etc.) and the like can also be cited. Among these, the binding resin used in the primer layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and particularly preferably a thermosetting resin such as a urea resin, a phenol resin, a phenol-formaldehyde resin, a melamine resin, a urethane resin, an unsaturated polyester resin, an alkyd resin, and an epoxy resin; or a resin obtained by reacting at least one resin selected from the group consisting of a polyamide resin, a polyester resin, a polyether resin, a methacrylic resin, an acrylic resin, a polyvinyl alcohol resin, and a polyvinyl acetal resin with a curing agent.

[0105] When two or more of these adhesive resins are used in combination, the mixing ratio thereof is set as needed.

[0106] In order to improve electrical characteristics, enhance environmental stability, and enhance image quality, various additives may be included in the undercoat layer.

[0107] Examples of additives include known materials such as polycyclic condensed and azo-based electron-transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but can also be added to the primer layer as an additive.

[0108] Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0109] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octylate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0110] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octylene glycollate, titanium ammonium lactate, titanium lactate, titanium ethyl lactate, titanium triethanolamine, and titanium polyhydroxystearate.

[0111] Examples of the aluminum chelate compound include aluminum isopropoxide, aluminum diisopropoxide / monobutoxide, aluminum butyrate, aluminum diethylacetoacetate / diisopropoxide, and aluminum tris(ethylacetoacetate).

[0112] These additives may be used alone or as a mixture or polycondensate of two or more compounds.

[0113] The Vickers hardness of the primer layer is preferably 35 or higher.

[0114] In order to suppress the moiré pattern, the surface roughness (ten-point average roughness) of the undercoat layer is adjusted to 1 / (4n) (n is the refractive index of the upper layer) to 1 / 2 of the wavelength λ of the exposure laser used.

[0115] To adjust the surface roughness, resin particles or the like may be added to the undercoat layer. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. Furthermore, to adjust the surface roughness, the surface of the undercoat layer may be ground. Examples of the grinding method include polishing, sandblasting, wet honing, and grinding.

[0116] The formation of the undercoat layer is not particularly limited and can be performed by a known formation method. For example, the above-mentioned components are added to a solvent to obtain a coating liquid for forming the undercoat layer, a coating film of the coating liquid for forming the undercoat layer is formed, and the coating film is dried and heated as needed.

[0117] Examples of the solvent used for preparing the coating liquid for forming the undercoat layer include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0118] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

[0119] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0120] Examples of methods for applying the coating liquid for forming an undercoat layer on a conductive substrate include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0121] The film thickness of the primer layer is set, for example, preferably within the range of 15 μm or more, and more preferably within the range of 20 μm or more and 50 μm or less.

[0122] (Middle layer)

[0123] Although not shown in the figure, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.

[0124] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used for the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, phenol-formaldehyde resins, and melamine resins.

[0125] The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0126] These compounds used for the intermediate layer may be used alone or as a mixture or polycondensate of two or more compounds.

[0127] Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

[0128] The formation of the intermediate layer is not particularly limited and can be carried out by a known formation method. For example, the above-mentioned components can be added to a solvent to obtain a coating liquid for forming the intermediate layer, a coating film of the coating liquid for forming the intermediate layer can be formed, and the coating film can be dried and heated as needed.

[0129] As a coating method for forming the intermediate layer, a common method such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, or a curtain coating method is used.

[0130] The thickness of the intermediate layer is preferably set to a range of, for example, 0.1 μm or more and 3 μm or less.

[0131] (Charge Generation Layer)

[0132] The charge generating layer is, for example, a layer comprising a charge generating material and a binder resin. Alternatively, the charge generating layer may be a vapor-deposited layer of the charge generating material. This vapor-deposited layer of the charge generating material is suitable when using a non-interference light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array.

[0133] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed-ring aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0134] Among these, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge-generating materials to cope with near-infrared laser exposure. Specifically, hydroxygallium phthalocyanine disclosed in Japanese Patent Application Laid-Open Nos. 5-263007 and 5-279591, chlorogallium phthalocyanine disclosed in Japanese Patent Application Laid-Open No. 5-98181, dichlorotin phthalocyanine disclosed in Japanese Patent Application Laid-Open Nos. 5-140472 and 5-140473, and titanyl phthalocyanine disclosed in Japanese Patent Application Laid-Open No. 4-189873 are more preferred.

[0135] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, preferred charge-generating materials include condensed-ring aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrin compounds; zinc oxide; trigonal selenium; and disazo pigments disclosed in Japanese Patent Application Publication No. 2004-78147 and Japanese Patent Application Publication No. 2005-181992.

[0136] The above-mentioned charge-generating materials can also be used when using non-interference light sources such as LEDs and organic EL image arrays with a central emission wavelength of 450nm to 780nm. However, from the perspective of resolution, when using a photosensitive layer in the form of a thin film of 20μm or less, the electric field intensity in the photosensitive layer increases, which can easily cause image defects such as so-called black spots due to charge reduction caused by charge injection from the substrate. This problem becomes more prominent when using charge-generating materials that are p-type semiconductors such as trigonal selenium and phthalocyanine pigments, which are prone to generating dark current.

[0137] In contrast, using n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments as charge-generating materials reduces the generation of dark current, and even in thin film form, image defects known as black spots can be suppressed. Examples of n-type charge-generating materials include, but are not limited to, compounds (CG-1) to (CG-27) described in paragraphs 0288 to 0291 of JP-A-2012-155282.

[0138] Note that the n-type is determined by the commonly used time-of-flight method based on the polarity of the photocurrent flowing, and the type in which electrons flow more easily as carriers than holes is called n-type.

[0139] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

[0140] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (condensation product of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. The term "insulating property" herein refers to a volume resistivity of 10 13 Ωcm or more.

[0141] These adhesive resins may be used alone or in combination of two or more.

[0142] The mixing ratio of the charge generating material to the binder resin is preferably within a range of 10:1 to 1:10 in terms of mass ratio.

[0143] The charge generating layer may further contain other known additives.

[0144] The charge generating layer can be formed without particular limitation and can be formed using known methods, for example, by adding the aforementioned components to a solvent to obtain a charge generating layer-forming coating solution, forming a coating film of the charge generating layer-forming coating solution, drying the coating film, and optionally heating. It should be noted that the charge generating layer can be formed by vapor deposition of the charge generating material. Formation of the charge generating layer by vapor deposition is particularly suitable when using condensed-ring aromatic pigments or perylene pigments as the charge generating material.

[0145] Examples of the solvent used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene. These solvents may be used alone or in combination of two or more.

[0146] Methods for dispersing particles (e.g., charge generating material) in the charge generating layer-forming coating liquid include, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, or a horizontal sand mill; a media-free disperser such as a stirrer, an ultrasonic disperser, a roller mill, or a high-pressure homogenizer. Examples of high-pressure homogenizers include a collision method in which the dispersion is dispersed by liquid-liquid collision or liquid-wall collision under high pressure; and a penetration method in which the dispersion is dispersed by penetrating a fine flow path under high pressure.

[0147] During the dispersion, it is effective to adjust the average particle size of the charge generating material in the charge generating layer-forming coating liquid to preferably 0.5 μm or less, more preferably 0.3 μm or less, and even more preferably 0.15 μm or less.

[0148] Examples of methods for applying the charge generating layer-forming coating liquid onto the undercoat layer (or intermediate layer) include common methods such as blade coating, wire rod coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0149] The film thickness of the charge generating layer is set, for example, preferably within the range of 0.1 μm to 5.0 μm, more preferably within the range of 0.2 μm to 2.0 μm.

[0150] (Charge Transport Layer)

[0151] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymer charge transport material.

[0152] Examples of charge transport materials include electron-transporting compounds such as p-benzoquinone, chloranil, bromoquinone, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and vinyl compounds. Other examples of charge transport materials include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited to these.

[0153] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) or a benzidine derivative represented by the following structural formula (a-2) is preferred.

[0154] [Chemistry 1]

[0155]

[0156] In the structural formula (a-1), Ar T1 、Ar T2 and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ), RT4 、R T5 、R T6 、R T7 and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0157] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0158] [Chemistry 2]

[0159]

[0160] In the structural formula (a-2), R T91 and R T92 Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, and R T101 、R T102 、R T111 and R T112 Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 or more and 2 or less carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ), R T12 、R T13 、R T14 、R T15 and R T16 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and Tm1, Tm2, Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.

[0161] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0162] Here, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), the one having "-C6H4-CH=CH-CH=C(R T7 )(R T8)" or a triarylamine derivative having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0163] As polymeric charge transport materials, known materials having charge transport properties, such as poly-N-vinylcarbazole and polysilane, are used. Polyester-based polymeric charge transport materials disclosed in Japanese Patent Application Laid-Open Nos. 8-176293 and 8-208820, etc., are particularly preferred. It should be noted that polymeric charge transport materials can be used alone or in combination with a binder resin.

[0164] The adhesive resin used in the charge transport layer can include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-modified alkyd resin, phenol-formaldehyde resin, styrene-modified alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among these, as the adhesive resin, preferably polycarbonate resin or polyarylate resin. These adhesive resins can be used alone or in combination.

[0165] The mixing ratio of the charge transport material to the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0166] The charge transport layer may further contain other known additives.

[0167] The charge transport layer may be formed without particular limitation and may be formed by a known method, for example, by adding the above-mentioned components to a solvent to obtain a charge transport layer-forming coating solution, forming a coating film of the charge transport layer-forming coating solution, drying the coating film, and heating as needed.

[0168] Examples of solvents used to prepare the charge transport layer coating solution include common organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and ethylene chloride; and cyclic or linear ethers such as tetrahydrofuran and diethyl ether. These solvents can be used alone or in combination of two or more.

[0169] Examples of the coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0170] The film thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, more preferably within the range of 10 μm to 30 μm.

[0171] (Surface protection layer)

[0172] A surface protective layer (hereinafter also referred to as a "protective layer") is preferably provided on the photosensitive layer. The protective layer is provided, for example, to prevent chemical changes in the photosensitive layer during charging and to further improve the mechanical strength of the photosensitive layer. Therefore, the protective layer may be a layer composed of a cured film (crosslinked film). Examples of such layers include the layers described in 1) or 2) below.

[0173] 1) A layer composed of a cured film of a composition containing a reactive group-containing charge transport material having a reactive group and a charge-transporting skeleton in the same molecule (ie, a layer containing a polymer or a crosslinked product of the reactive group-containing charge transport material).

[0174] 2) A layer composed of a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge transport skeleton but having a reactive group (i.e., a layer comprising a polymer or crosslinked body of the reactive group-containing non-charge transport material and the non-reactive charge transport material).

[0175] Examples of the reactive group include chain polymerizable groups, epoxy groups, -OH, -OR (wherein R represents an alkyl group), -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 ) Qn (Among them, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group or a trialkylsilyl group, and Qn represents an integer of 1 to 3. Examples of the reactive group in the reactive group-containing non-charge transport material include the aforementioned reactive groups.

[0176] As a chain polymerizable group, there is no particular limitation as long as it is a functional group that can undergo free radical polymerization. As a chain polymerizable group, for example, there can be mentioned: a functional group containing a group having an ethylenically unsaturated bond. Specifically, as a functional group having an ethylenically unsaturated bond, there can be mentioned: a group having at least one selected from the group consisting of a vinyl group, a vinyl ether group, a vinyl sulfide group, a styryl (vinylphenyl), an acryloyl group, a methacryloyl group and their derivatives. Among the above, for the reason of excellent reactivity, as a chain polymerizable group, it is preferably a group having at least one selected from the group consisting of a vinyl group, a styryl (vinylphenyl), an acryloyl group, a methacryloyl group and their derivatives, more preferably a group having at least one selected from the group consisting of an acryloyl group, a methacryloyl group and their derivatives, and further preferably a group having at least one of an acryloyl group and a methacryloyl group.

[0177] The charge transport skeleton is not particularly limited as long as it is a known structure in image holding materials. Examples thereof include a structure that is derived from a nitrogen-containing hole transporting compound such as a triarylamine compound (a compound having a triarylamine skeleton), a benzidine compound (a compound having a benzidine skeleton), or a hydrazone compound (a compound having a hydrazone skeleton) and is conjugated with a nitrogen atom. Among these, the charge transport skeleton preferably includes a triarylamine skeleton.

[0178] The reactive group-containing charge transport material, the non-reactive charge transport material, and the reactive group-containing non-charge transport material can be selected from publicly known materials.

[0179] Regarding the surface protective layer, of the above 1) and 2), preferably, the surface protective layer 1) is composed of a cured product of a composition containing a reactive group-containing charge transport material having a reactive group and a charge-transporting skeleton in the same molecule. When the surface protective layer is composed of a cured product of a composition containing a reactive group-containing charge transport material having a reactive group and a charge-transporting skeleton in the same molecule as described in 1), the surface protective layer tends to have a higher hardness than a surface protective layer composed of a cured product according to the embodiment described in 2).

[0180] The reactive group-containing charge transport material preferably includes a reactive group-containing charge transport material having at least one of an acryloyl group and a methacryloyl group as a reactive group (hereinafter also referred to as “specific reactive group-containing charge transport material (a)”).

[0181] ·Specific reactive group-containing charge transport material (a)

[0182] The specific reactive group-containing charge transport material (a) used in the surface protective layer is a compound having a charge transport skeleton and an acryloyl group or a methacryloyl group in the same molecule and is not particularly limited as long as the structural requirements are met.

[0183] The specific reactive group-containing charge transport material (a) is preferably a compound having a methacryloyl group. The reason for this is not clear, but it is presumed to be as follows. Typically, compounds having highly reactive acryloyl groups are used in the curing reaction. In the case of having a highly reactive acryloyl group as a substituent on a bulky charge transport skeleton, unevenness is likely to occur in the curing reaction, and therefore unevenness and wrinkles in the surface protective layer are likely to occur in the cured film. On the other hand, it is presumed that by using a specific reactive group-containing charge transport material (a) having a methacryloyl group having a lower reactivity than an acryloyl group, unevenness and wrinkles in the surface protective layer in the cured film are easily suppressed.

[0184] The specific reactive group-containing charge transport material (a) preferably has a structure in which one or more carbon atoms are inserted between the charge transport backbone and the acryloyl group or methacryloyl group. Specifically, the specific reactive group-containing charge transport material (a) preferably has a carbon chain containing one or more carbon atoms as a linking group between the charge transport backbone and the acryloyl group or methacryloyl group. In particular, an alkylene group is the most preferred linking group.

[0185] The reasons for preferring the above embodiment are not necessarily clear, but the following reasons are considered, for example: Regarding the mechanical strength of the surface protective layer, it is believed that if the bulky charge-transporting backbone is close to the polymerization site (acryloyl or methacryloyl group) and is rigid (rigid), the polymerization sites are less likely to be active with each other, which may reduce the probability of reaction.

[0186] Furthermore, a preferred embodiment is a compound (a') in which the specific reactive group-containing charge transport material (a) is a structure having a triphenylamine skeleton and three or more, more preferably four or more, methacryloyl groups in the same molecule. In this embodiment, the stability of the compound during synthesis is easily ensured. In addition, this embodiment allows the formation of a surface protective layer with a high crosslinking density and sufficient mechanical strength, thereby easily achieving a thicker surface protective layer.

[0187] In the present embodiment, the specific reactive group-containing charge transport material (a) is preferably a compound represented by the following general formula (A), since the charge transport property is excellent.

[0188] [Chemistry 3]

[0189]

[0190] In the above general formula (A), Ar1 ~Ar 4 Each independently represents a substituted or unsubstituted aryl group, Ar 5 represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted arylene group, and D represents -(CH2) d -(O-CH2-CH2) e -O-CO-C(CH3)=CH2, c1 to c5 each independently represent an integer of 0 or more and 2 or less, k represents 0 or 1, d represents an integer of 0 or more and 5 or less, e represents 0 or 1, and the total number of D is 4 or more.

[0191] In the general formula (A), Ar 1 ~Ar 4 Each independently represents a substituted or unsubstituted aryl group. 1 ~Ar 4 They may be the same or different.

[0192] Here, as a substituent in the substituted aryl group, D: -(CH2) d -(O-CH2-CH2) e Examples of groups other than -O-CO-C(CH3)=CH2 include alkyl or alkoxy groups having 1 to 4 carbon atoms, and substituted or unsubstituted aryl groups having 6 to 10 carbon atoms.

[0193] As Ar 1 ~Ar 4 , preferably any one of the following formulas (1) to (7). It should be noted that the following formulas (1) to (7) and "-(D) C ” are shown together, where “-(D) C "Generally speaking, they can be compared with Ar 1 ~Ar 4 Linked "-(D) C1 ”~“-(D) C4 ”.

[0194] [Chemistry 4]

[0195]

[0196] In the above formulas (1) to (7), R 1 represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, and an aralkyl group having 7 to 10 carbon atoms, and R 2 ~R 4Each independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted by an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, Ar represents a substituted or unsubstituted arylene group, and D represents -(CH2) d -(O-CH2-CH2) e -O-CO-C(CH3)=CH2, c represents 1 or 2, s represents 0 or 1, and t represents an integer of 0 or more and 3 or less.

[0197] Here, as Ar in formula (7), a group represented by the following structural formula (8) or (9) is preferred.

[0198] [Chemistry 5]

[0199]

[0200] In the above formulas (8) and (9), R 5 and R 6 Each independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted by an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and t' represents an integer of 0 to 3.

[0201] In the above formula (7), Z' represents a divalent organic linking group, preferably represented by any one of the following formulas (10) to (17). In the above formula (7), s represents 0 or 1.

[0202] [Chemistry 6]

[0203]

[0204] In the above formulas (10) to (17), R 7 and R 8 Each independently represents one member selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom; W represents a divalent group; q and r each independently represent an integer of 1 to 10; and t" each independently represents an integer of 0 to 3.

[0205] W in the above formulae (16) to (17) is preferably any of the divalent groups represented by the following formulae (18) to (26): In formula (25), u represents an integer of 0 or more and 3 or less.

[0206] [Chemistry 7]

[0207]

[0208] In the general formula (A), when k is 0, Ar 5 is a substituted or unsubstituted aryl group, and examples of the aryl group include 1 ~Ar 4 The same group as the aryl group exemplified in the description of . In addition, when k is 1, Ar 5 is a substituted or unsubstituted arylene group, and examples of the arylene group include Ar 1 ~Ar 4 The arylene group obtained by removing one hydrogen atom at the following position from the aryl group exemplified in the description of 3 -(D) C3 )(Ar 4 -(D) C4 ) is replaced by .

[0209] Specific examples of the compound represented by general formula (A) include the compounds described in paragraphs 0236 to 0240 of JP-A-2018-4968.

[0210] Examples of methods for producing the compound represented by general formula (A) include the methods described in paragraphs 0241 to 0244 of JP-A-2018-4968.

[0211] The reactive charge transport material may also contain a compound other than the specific reactive group-containing charge transport material (a) (hereinafter also referred to as "other reactive charge transport material (a")"). As the other reactive charge transport material, a compound obtained by introducing an acryloyl group or a methacryloyl group into a known charge transport material is used.

[0212] The ratio of the specific reactive group-containing charge transport material (a) to the reactive group-containing charge transport material is preferably 90% by mass or more and 100% by mass or less, and more preferably 98% by mass or more and 100% by mass or less.

[0213] The content of the reactive group-containing charge transport material is preferably from 30% to 100% by mass, more preferably from 40% to 100% by mass, and even more preferably from 50% to 100% by mass, relative to the composition (solid content) used to form the surface protective layer. By setting the content within this range, the cured film has excellent electrical properties and can be made thick.

[0214] The hardness (universal hardness) of the surface protection layer is preferably 140 N / mm 2 Above 300N / mm 2Below, more preferably 160mN / mm 2 Above 280N / mm 2 Below, more preferably 180mN / mm 2 Above 260mN / mm 2 the following.

[0215] The universal hardness of the surface protection layer is measured by the following method.

[0216] The universal hardness of the surface protection layer is the universal hardness obtained by performing a hardness test using a Vickers square pyramid diamond indenter at a maximum load of 20 mN in an environment of 25° C. and a relative humidity of 50%.

[0217] (Details of measurement)

[0218] As a measuring device, a Fischerscope H100V (microhardness measuring device) manufactured by Fischer Instruments was used. The indenter used in the measurement was a Vickers square pyramid diamond indenter with an angle of 136° between opposite faces.

[0219] (Measurement conditions)

[0220] Loading conditions: The Vickers indenter was pressed into the surface of the surface protective layer of the image holding member at a speed of 4 mN / sec.

[0221] Loading time: 5 seconds.

[0222] Hold time: 5 seconds.

[0223] Unloading condition: Remove the load at the same speed as the load.

[0224] The sample was fixed to an H100V machine and a Vickers indenter was pressed perpendicularly into the surface of the surface protective layer. The measurement was performed in a process of indenter loading (5 seconds), holding the load (5 seconds), and then unloading.

[0225] The protective layer may also contain other known additives.

[0226] The formation of the protective layer is not particularly limited and can be performed using a known formation method, for example, by adding the above-mentioned components to a solvent to obtain a coating liquid for forming a protective layer, forming a coating film of the coating liquid for forming a protective layer, drying the coating film, and performing a curing treatment such as heating as needed.

[0227] Examples of solvents used to prepare the protective layer-forming coating liquid include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents can be used alone or in mixtures of two or more. It should be noted that the protective layer-forming coating liquid may also be solvent-free.

[0228] Examples of methods for applying the protective layer-forming coating liquid onto the photosensitive layer (e.g., charge transport layer) include common methods such as dip coating, extrusion coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating.

[0229] The film thickness of the protective layer is set to, for example, preferably within the range of 1 μm to 20 μm, more preferably within the range of 2 μm to 10 μm.

[0230] (Single-layer photosensitive layer)

[0231] The single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer containing a charge generation material and a charge transport material and, if necessary, a binder resin and other known additives. It should be noted that these materials are the same as those described for the charge generation layer and charge transport layer.

[0232] Furthermore, in the single-layer photosensitive layer, the content of the charge generating material is preferably from 0.1% by mass to 10% by mass, more preferably from 0.8% by mass to 5% by mass, relative to the total solids content of the single-layer photosensitive layer. Furthermore, in the single-layer photosensitive layer, the content of the charge transport material is preferably from 5% by mass to 50% by mass, relative to the total solids content.

[0233] The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generating layer and the charge transporting layer.

[0234] The film thickness of the single-layer photosensitive layer is preferably, for example, 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

[0235] [Charging mechanism]

[0236] The image forming apparatus of this embodiment preferably includes a charging mechanism for charging the surface of the image holding member.

[0237] The charging mechanism 15 charges the surface of the image holder 12. The charging mechanism 15 includes, for example, a charging member 14 disposed in contact with or without contact with the surface of the image holder 12 to charge the surface of the image holder 12, and a power source 28 (an example of a voltage application unit for the charging member) that applies a charging voltage to the charging member 14. The power source 28 is electrically connected to the charging member 14.

[0238] Examples of the charging member 14 of the charging mechanism 15 include contact-type chargers using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like. Furthermore, examples of the charging member 14 include non-contact-type roller chargers, scorotron chargers or corona chargers utilizing corona discharge, and other known chargers.

[0239] [Latent image forming mechanism]

[0240] The latent image forming mechanism 16 forms an electrostatic latent image on the charged surface of the image holding member 12. Specifically, for example, the latent image forming mechanism 16 irradiates the surface of the image holding member 12 charged by the charging member 14 with light L modulated based on image information of the image to be formed, thereby forming an electrostatic latent image corresponding to the image information on the image holding member 12.

[0241] As the latent image forming means 16 , for example, there can be mentioned an optical device having a light source for exposing light in an image-forming manner, such as semiconductor laser, LED light, or liquid crystal shutter light.

[0242] [Development mechanism]

[0243] The developing mechanism 18 is disposed, for example, downstream of the position where the latent image forming mechanism 16 irradiates the image holder 12 in the rotational direction. A storage portion for storing a developer is provided within the developing mechanism 18. This storage portion stores an electrostatic image developer containing a specific electrostatic image developing toner. The electrostatic image developing toner is stored within the developing mechanism 18 in a charged state, for example.

[0244] The developing mechanism 18 includes, for example, a developing member 18A for developing the electrostatic image formed on the surface of the image holder 12 using a developer containing electrostatic image developing toner, and a power source 32 for applying a development voltage to the developing member 18A. The developing member 18A is electrically connected to the power source 32, for example.

[0245] The developing member 18A of the developing mechanism 18 is selected according to the type of developer, and an example thereof is a developing roller having a developing sleeve with a built-in magnet.

[0246] The developing mechanism 18 (including the power supply 32) is electrically connected to, for example, a control mechanism 36 provided in the image forming apparatus 10. The control mechanism 36 controls the driving of the developing member 18A, thereby applying a development voltage to the developing member 18A. Upon application of the development voltage, the developing member 18A is charged to a development potential corresponding to the development voltage. The developing member 18A, charged to the development potential, then holds the developer stored within the developing mechanism 18 on its surface and supplies the electrostatic image developing toner contained in the developer from the developing mechanism 18 to the surface of the image holder 12. The formed electrostatic image is developed as an electrostatic image developing toner image on the surface of the image holder 12 to which the electrostatic image developing toner has been supplied.

[0247] [Transfer agency]

[0248] The transfer mechanism 31 is provided, for example, downstream of the position of the developing unit 18A in the rotational direction of the image holder 12. The transfer mechanism 31 includes, for example, a transfer unit 20 for transferring an electrostatic developing toner image formed on the surface of the image holder 12 to a recording medium 30A, and a power supply 30 for applying a transfer voltage to the transfer unit 20. The transfer unit 20 is, for example, cylindrical in shape, and transports the recording medium 30A while sandwiching it between the image holders 12. The transfer unit 20 is, for example, electrically connected to the power supply 30.

[0249] Examples of the transfer member 20 include a contact transfer charger using a belt, roller, film, or rubber cleaning blade, and a known non-contact transfer charger such as a scorotron transfer charger or a corona transfer charger using corona discharge.

[0250] The transfer mechanism 31 (including the power supply 30) is electrically connected to, for example, a control mechanism 36 provided in the image forming apparatus 10, and is driven and controlled by the control mechanism 36 to apply a transfer voltage to the transfer member 20. The transfer member 20, to which the transfer voltage is applied, is charged to a transfer potential corresponding to the transfer voltage.

[0251] When a transfer voltage is applied to the transfer member 20 by the power supply 30 of the transfer member 20 and the polarity of the transfer voltage is opposite to that of the electrostatic image developing toner constituting the electrostatic image developing toner image formed on the image holding member 12, for example, in the area ( Figure 1 In the figure, a transfer electric field is formed in the transfer area 32A, and the electric field strength of the transfer electric field is such that each electrostatic image developing toner constituting the electrostatic image developing toner image on the image holding body 12 migrates from the image holding body 12 to the transfer member 20 side by electrostatic force.

[0252] The recording medium 30A is stored in a storage unit (not shown), and is transported from the storage unit along a transport path 34 by two or more transport members (not shown) to a transfer area 32A where the image holder 12 and the transfer member 20 face each other. Figure 1 In the example shown in FIG, the recording medium 30A is transported in the direction of arrow B. The recording medium 30A that has reached the transfer region 32A transfers the electrostatic image developing toner image on the image holder 12 due to, for example, a transfer electric field formed in that region by applying a transfer voltage to the transfer member 20. Specifically, for example, the electrostatic image developing toner image migrates from the surface of the image holder 12 to the recording medium 30A, thereby transferring the electrostatic image developing toner image to the recording medium 30A. Thus, the electrostatic image developing toner image on the image holder 12 is transferred to the recording medium 30A by the transfer electric field.

[0253] [Cleaning mechanism (cleaning mechanism)]

[0254] The image forming device in this embodiment has a cleaning mechanism for removing residual toner on the above-mentioned image retaining body, and the above-mentioned cleaning mechanism has mechanism A or mechanism B. Mechanism A has a cleaning scraper that contacts the surface of the above-mentioned image retaining body, and the JIS-A hardness of the abutment portion of the above-mentioned cleaning scraper that contacts the above-mentioned image retaining body is greater than 90 degrees. Mechanism B has a cleaning scraper that contacts the surface of the above-mentioned image retaining body, and the abutment load of the above-mentioned cleaning scraper with the above-mentioned image retaining body is controlled by a constant load method.

[0255] The cleaning mechanism may be either mechanism A or mechanism B, or a mechanism that satisfies both mechanisms A and B. Specifically, the cleaning mechanism may include a cleaning blade that contacts the surface of the image holder, wherein the JIS-A hardness of the portion of the cleaning blade that contacts the image holder is 90 degrees or greater, and the contact load of the cleaning blade with the image holder is controlled using a constant load method. In this method, the resulting image exhibits excellent image defect suppression.

[0256] Among them, from the viewpoint of suppressing image defects in the obtained image, the cleaning mechanism is preferably a mechanism that satisfies both the mechanism A and the mechanism B.

[0257] The cleaning mechanism 22 is provided downstream of the transfer area 32A in the rotational direction of the image holder 12. After the electrostatic image developing toner image is transferred to the recording medium 30A, the cleaning mechanism 22 cleans (sweeps and removes) residual toner adhering to the image holder 12. The cleaning mechanism 22 not only cleans the residual toner but also removes adhering matter such as paper dust.

[0258] The cleaning mechanism 22 includes a cleaning blade 220 , and removes adhering matter on the surface of the image holding member 12 by making the front end of the cleaning blade 220 contact the image holding member 12 in a direction opposite to the rotation direction of the image holding member 12 .

[0259] Here, refer to Figure 4 The cleaning mechanism 22 will be described.

[0260] Figure 4 It shows Figure 1 FIG. 2 is a schematic structural diagram showing the arrangement of the cleaning blade 220 in the cleaning mechanism 22 .

[0261] like Figure 4 As shown, the front end of the cleaning blade 220 is directed in the direction opposite to the rotation direction (arrow direction) of the image holding member 12 and is in contact with the surface of the image holding member 12 in this state.

[0262] The angle θ between the cleaning blade 220 and the image holding member 12 is preferably set to 5° or more and 35° or less, and more preferably set to 10° or more and 25° or less.

[0263] In addition, the pressing pressure N of the cleaning blade 220 against the image holding member 12 is preferably set to 0.6 gf / mm 2 Above 6.0gf / mm 2 the following.

[0264] Here, regarding the above angle θ, as Figure 4 Specifically, it refers to the tangent line of the contact portion between the front end of the cleaning blade 220 and the image holding member 12 ( Figure 4 The angle formed by the dot-dash line in FIG. 1 and the non-deformed portion of the cleaning blade 220.

[0265] In addition, if Figure 4 As shown in FIG. 1 , the pressing pressure N is the pressure (gf / mm2) applied to the center of the image holder 12 at the position where the cleaning blade 220 contacts the image holder 12. 2 ).

[0266] In the cleaning blade 220, the supporting member ( Figure 4 The cleaning blade 220 is supported by a support member (not shown) attached to the side opposite the contact surface of the image holder 12. The cleaning blade 220 is pressed against the image holder 12 with the aforementioned pressing pressure using the support member. Examples of the support member include metal materials such as aluminum and stainless steel. It should be noted that a bonding layer formed of an adhesive or the like may be provided between the support member and the cleaning blade 220 to bond the two.

[0267] The cleaning mechanism may further include known components other than the cleaning blade 220 and the supporting member for supporting the cleaning blade 220 .

[0268] (Organization A)

[0269] The mechanism A includes a cleaning blade that contacts the surface of the image holding member, wherein a JIS-A hardness of a portion of the cleaning blade that contacts the image holding member is 90 degrees or higher.

[0270] The cleaning blade is preferably constructed such that at least the portion that contacts the image holder comprises a plate-shaped rubber substrate. The cleaning blade may have a single-layer structure of the rubber substrate, or a laminated structure in which a back layer is laminated on the back side of the rubber substrate (the side not facing the image holder). The back layer may be multi-layered.

[0271] The rubber substrate includes rubber as a whole. Here, rubber refers to a polymer compound having rubber elasticity at room temperature (25°C). Examples of rubber include polyurethane, silicone rubber, fluororubber, chloroprene rubber, butadiene rubber, and the like. Among the above rubbers, polyurethane is preferred as the rubber substrate, and highly crystalline polyurethane is more preferred.

[0272] Polyurethane is usually synthesized by polymerization of polyisocyanates and polyols. In addition, resins having functional groups other than polyols that can react with isocyanate groups can also be used. It should be noted that the polyurethane preferably has a hard segment and a soft segment.

[0273] Here, in polyurethane, "hard segments" and "soft segments" mean segments in which the former is composed of a relatively harder material than the latter, and segments in which the latter is composed of a relatively softer material than the former.

[0274] The combination of the material constituting the hard segment (hard segment material) and the material constituting the soft segment (soft segment material) is not particularly limited and can be selected from known materials so that one is relatively harder than the other and the other is relatively softer than the first. The following combination is preferred.

[0275] Soft segment materials

[0276] First, as a soft segment material, polyols include polyester polyols obtained by dehydration condensation of a diol and a dibasic acid, polycarbonate polyols obtained by reaction of a diol and an alkyl carbonate, polycaprolactone polyols, polyether polyols, etc. It should be noted that commercially available products of the above-mentioned polyols used as soft segment materials include, for example, PRAXCELL 205 and PRAXCELL 240 manufactured by Daicel.

[0277] Hard segment materials

[0278] In addition, resins having functional groups reactive with isocyanate groups are preferably used as hard segment materials. Furthermore, flexible resins are preferred, and aliphatic resins having a linear structure are more preferred from the perspective of flexibility. Specific examples include acrylic resins containing two or more hydroxyl groups, polybutadiene resins containing two or more hydroxyl groups, and epoxy resins containing two or more epoxy groups.

[0279] Examples of commercially available products of acrylic resins containing two or more hydroxyl groups include Actflow (grades: UMB-2005B, UMB-2005P, UMB-2005, UME-2005, etc.) manufactured by Soken Chemical Industries, Ltd.

[0280] Examples of commercially available products of the polybutadiene resin containing two or more hydroxyl groups include R-45HT manufactured by Idemitsu Kosan Co., Ltd.

[0281] The epoxy resin having two or more epoxy groups is preferably a resin that is softer and more resilient than conventional epoxy resins, rather than being hard and brittle like conventional epoxy resins. The epoxy resin preferably has a main chain structure (flexible backbone) that enhances main chain mobility, for example, in terms of molecular structure. Examples of the flexible backbone include alkylene backbones, cycloalkane backbones, and polyoxyalkylene backbones, with polyoxyalkylene backbones being particularly preferred.

[0282] Furthermore, from the perspective of physical properties, epoxy resins with a lower viscosity relative to their molecular weight than existing epoxy resins are suitable. Specifically, the weight-average molecular weight is within the range of 900 ± 100, and the viscosity at 25°C is preferably within the range of 15,000 ± 5,000 mPa·s, more preferably within the range of 15,000 ± 3,000 mPa·s. Commercially available epoxy resins with these properties include, for example, EPLICON EXA-4850-150 manufactured by DIC Corporation.

[0283] When using hard segment materials and soft segment materials, the mass ratio of the material constituting the hard segment relative to the total amount of the hard segment material and the soft segment material (hereinafter referred to as the "hard segment material ratio") is preferably in the range of 10 mass% to 30 mass%, more preferably in the range of 13 mass% to 23 mass%, and further preferably in the range of 15 mass% to 20 mass%.

[0284] By setting the hard segment material ratio to 10% by mass or more, wear resistance can be achieved. On the other hand, by setting the hard segment material ratio to 30% by mass or less, flexibility and stretchability can be achieved while avoiding excessive hardness, thereby suppressing the occurrence of flaking.

[0285] Polyisocyanate

[0286] Examples of polyisocyanates used in the synthesis of polyurethane include 4,4′-diphenylmethane diisocyanate (MDI), 2,6-toluene diisocyanate (TDI), 1,6-hexane diisocyanate (HDI), 1,5-naphthalene diisocyanate (NDI), and 3,3-dimethylphenyl-4,4-diisocyanate (TODI).

[0287] In addition, from the viewpoint of easily forming hard segment aggregates of a desired size (particle diameter), the polyisocyanate is more preferably 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), or hexamethylene diisocyanate (HDI).

[0288] The amount of the polyisocyanate compounded per 100 parts by mass of the resin having a functional group reactive with an isocyanate group is preferably 20 parts by mass to 40 parts by mass, more preferably 20 parts by mass to 35 parts by mass, and even more preferably 20 parts by mass to 30 parts by mass.

[0289] By setting the compounding amount to 20 parts by mass or more, a high amount of urethane bonds is ensured, which allows the hard segments to grow and achieve the desired hardness. On the other hand, by setting the compounding amount to 40 parts by mass or less, the hard segments do not become too large, and stretchability is achieved, which can suppress blade peeling.

[0290] Cross-linking agent

[0291] Examples of crosslinking agents include diols (2-functional), triols (3-functional), and tetraols (4-functional), and these can be used in combination. Amine compounds can also be used as crosslinking agents. It should be noted that it is preferred to use a crosslinking agent with three or more functional groups for crosslinking. Examples of trifunctional crosslinking agents include trimethylolpropane, glycerol, and triisopropanolamine.

[0292] The amount of the crosslinking agent blended is preferably 2 parts by mass or less per 100 parts by mass of the resin having a functional group reactive with an isocyanate group. By setting the blending amount to 2 parts by mass or less, molecular motion is not restricted by chemical crosslinking, and hard segments derived from urethane bonds upon aging grow significantly, making it easier to achieve the desired hardness.

[0293] ·Molding method of rubber substrate

[0294] The rubber substrate comprising polyurethane as an example of rubber is produced using a general polyurethane production method such as a prepolymer method or a one-shot method. The prepolymer method is preferred because it can produce polyurethane with excellent strength and wear resistance, but the method is not limited thereto.

[0295] Polyurethane is formed by mixing a polyisocyanate compound and a crosslinking agent with the aforementioned polyol. The rubber substrate is formed by forming the rubber substrate-forming composition prepared by the aforementioned method into a sheet by, for example, centrifugal molding or extrusion molding, and then cutting the sheet.

[0296] ·Physical properties

[0297] When the rubber contained in the rubber base material is polyurethane, the weight average molecular weight of the polyurethane is preferably in the range of 1,000 to 4,000, and more preferably in the range of 1,500 to 3,500.

[0298] From the viewpoint of suppressing image defects in the obtained image, it is preferable that the JIS-A hardness (H) of at least the portion of the cleaning blade in contact with the image holder be greater than 0.05. BLD ) is 60 degrees or more, more preferably 70 degrees or more, further preferably 90 degrees or more, and particularly preferably 90 degrees or more and 100 degrees or less.

[0299] The JIS-A hardness is a value measured using a type A durometer specified in JIS K 7215 (1986) in accordance with the hardness test method described in JIS K 7311 (1995).

[0300] The contact portion with the image holder refers to both a portion where the cleaning blade contacts the image holder when the rotation of the image holder stops and a portion where the cleaning blade contacts the image holder when the image holder rotates.

[0301] In order to make the JIS-A hardness of at least the contact part of the cleaning scraper with the image retaining body be above 90 degrees, for example, the following methods can be cited: a method of adjusting by the material of the abutting part; a method of curing the abutting part; a method of adjusting the combination of the hard segment material and the soft segment material; a method of adjusting the material ratio (mixing ratio) of the hard segment material and the soft segment material; a method of adjusting the curing conditions (such as aging time, aging temperature) of the composition for forming the rubber substrate (composition for cleaning scraper molding).

[0302] From the perspective of suppressing image defects in the obtained image, the hardness (H BLD ) and the hardness of the surface protective layer (H OCL ) ratio (H BLD / H OCL ) is preferably 0.8 or less, more preferably 0.7 or less, and further preferably 0.6 or less.

[0303] In addition, from the perspective of suppressing image defects in the obtained image, the above-mentioned cleaning scraper is preferably a laminated scraper, and more preferably a laminated scraper containing a layer with a JIS-A hardness of 90 degrees or more and a layer with a low hardness, wherein the hardness of the layer with a low hardness is lower than that of the above-mentioned layer with a JIS-A hardness of 90 degrees or more.

[0304] In addition, from the perspective of suppressing image defects in the obtained image, the difference in hardness between the layer with a JIS-A hardness of 90 degrees or more and the layer with a lower hardness in the cleaning blade is preferably 10 degrees or more, more preferably 15 degrees or more, further preferably 15 degrees or more and 40 degrees or less, and particularly preferably 20 degrees or more and 30 degrees or less in terms of JIS-A hardness.

[0305] Furthermore, from the perspective of suppressing image defects in the obtained image, the cleaning scraper whose JIS-A hardness of the above-mentioned abutment portion is 90 degrees or more is preferably a cleaning scraper whose above-mentioned abutment portion is solidified, and more preferably a laminated scraper having a solidified layer on the above-mentioned abutment portion side.

[0306] The above-mentioned laminated scraper can be a laminated scraper with more than 2 layers. From the perspective of suppressing image defects in the obtained image, it is preferably a laminated scraper with 2 or 3 layers, more preferably a laminated scraper with 2 layers, and particularly preferably a laminated scraper containing a layer with a JIS-A hardness of 90 degrees or more and a layer with a lower hardness (which has a lower hardness than the above-mentioned layer with a JIS-A hardness of 90 degrees or more).

[0307] There is no particular restriction on the material of each layer in the laminated scraper, and the above-mentioned rubber substrate can be cited. In addition, the material of each layer can be the same type of resin or different types of resin. From the perspective of image defect suppression in the obtained image, it is preferably a laminated scraper containing two or more resin layers of the same type but different hardness, more preferably a laminated scraper containing two or more polyurethane layers with different hardness, and particularly preferably a laminated scraper containing a cured polyurethane layer and an uncured polyurethane layer.

[0308] The curing treatment is not particularly limited, and a known curing treatment may be appropriately selected according to the type of resin used.

[0309] For example, treatment using a known cross-linking agent, known heat treatment, etc. can be mentioned.

[0310] Specifically, for example, the following method can be appropriately cited: the above-mentioned polyisocyanate, the above-mentioned diol, the above-mentioned triol, the above-mentioned tetraol and other multifunctional alcohol compounds, the above-mentioned amine compounds and other cross-linking agents are applied and / or impregnated onto the surface of the side including the above-mentioned abutting portion of the cleaning blade containing polyurethane, and heat-treated as needed.

[0311] The thickness of each layer in the laminated blade can be appropriately set as desired, and each layer does not necessarily need to have a fixed thickness.

[0312] For example, from the perspective of suppressing image defects in the obtained image, in the above-mentioned laminated scraper containing a layer with a JIS-A hardness of 90 degrees or more and a layer with a lower hardness than the above-mentioned layer with a JIS-A hardness of 90 degrees or more, the thickness of the above-mentioned layer with a JIS-A hardness of 90 degrees or more is preferably 0.01 mm or more and 1.0 mm or less, and more preferably 0.1 mm or more and 0.5 mm or less.

[0313] Furthermore, from the perspective of suppressing image defects in the obtained image, the thickness of the layer having a JIS-A hardness of 90 degrees or higher is preferably 1 / 2 or less, more preferably 1 / 4 or less, of the thickness of the entire laminated blade.

[0314] The overall thickness of the cleaning blade is not particularly limited, but is preferably 0.1 mm to 10 mm, more preferably 0.1 mm to 3.0 mm, and even more preferably 0.2 mm to 2.0 mm.

[0315] The width of the cleaning blade is not particularly limited and may be appropriately set according to the width of the image holding member.

[0316] Furthermore, the length of the cleaning blade is not particularly limited and may be appropriately set according to the shape of the image forming apparatus and other requirements.

[0317] (Organization B)

[0318] The mechanism B includes a cleaning blade that contacts the surface of the image holding member, and is a mechanism in which the contact load of the cleaning blade with the image holding member is controlled by a constant load method.

[0319] In addition, various preferred aspects of the above-mentioned mechanism A are also preferred aspects of the above-mentioned mechanism B.

[0320] The contact load between the cleaning scraper controlled by a constant load method in the above-mentioned mechanism B and the above-mentioned image retaining body does not have to be a completely constant load, as long as it is a constant load to a certain extent, for example, it is preferably within a load change of ±30%, more preferably within a load change of ±20%, and particularly preferably within a load change of ±10%.

[0321] The contact load is not particularly limited and may be appropriately set as needed. The pressing pressure of the cleaning blade against the image holding member is preferably 1.0 gf / mm. 2 Above 6.0gf / mm 2 the following.

[0322] As the member for performing control by the constant load method in the mechanism B, it is preferable to include an elastic member.

[0323] The elastic member is not particularly limited, and examples thereof include spring members and foam members.

[0324] In addition, the mechanism B is preferably connected to the housing of the image forming apparatus via an elastic member.

[0325] In the mechanism B, the elastic member and the cleaning blade are preferably connected via a supporting member.

[0326] The material and shape of the supporting member are not particularly limited and can be appropriately set.

[0327] Furthermore, in order to further stabilize the contact load, the mechanism B may include a weight member for applying a load in a direction in which the cleaning blade contacts the image holding member.

[0328] Figure 5 A schematic cross-sectional view showing an example of a mechanism B in the image forming apparatus according to the present embodiment is shown.

[0329] exist Figure 5 In the case of the constant load method in the example of the mechanism B shown, the support member 91 is supported by a housing in the image forming apparatus or a member 94 fixed to the housing via an elastic member such as a spring member 92. Therefore, the cleaning blade 51 changes its position according to changes in the reaction force from the image holder 41, and is pressed against the image holder 41 with the above-mentioned constant load.

[0330] It should be noted that Figure 5 In reality, the cleaning blade 51 receives a reaction force from the image holding member 41 and is deformed.

[0331] [Static elimination mechanism]

[0332] The image forming apparatus of this embodiment preferably includes a static elimination mechanism that exposes the surface of the image holding member to eliminate static electricity after the toner image for electrostatic image development is transferred.

[0333] The static elimination mechanism 24 is provided, for example, downstream of the cleaning mechanism 22 in the rotational direction of the image holder 12. The static elimination mechanism 24 removes static electricity by exposing the surface of the image holder 12 after the toner image for electrostatic image development has been transferred. Specifically, for example, the static elimination mechanism 24 is electrically connected to a control mechanism 36 provided in the image forming apparatus 10, and is driven and controlled by the control mechanism 36 to expose the entire surface of the image holder 12 (specifically, the entire surface of the imaging area, for example) to remove static electricity.

[0334] Examples of the static eliminating mechanism 24 include a tungsten lamp that emits white light and a device having a light source such as a light emitting diode (LED) that emits red light.

[0335] [Fixing mechanism]

[0336] The image forming apparatus according to the present embodiment preferably includes a fixing mechanism that fixes the toner image transferred to the recording medium.

[0337] The fixing mechanism 26 is provided, for example, downstream of the transfer area 32A in the conveyance direction of the recording medium 30A along the conveyance path 34. The fixing mechanism 26 includes a fixing member 26A and a pressure member 26B disposed in contact with the fixing member 26A. The fixing mechanism 26 fixes the electrostatic developing toner image transferred onto the recording medium 30A at the contact portion between the fixing member 26A and the pressure member 26B. Specifically, for example, the fixing mechanism 26 is electrically connected to a control mechanism 36 provided in the image forming apparatus 10. Drive control by the control mechanism 36 fixes the electrostatic developing toner image transferred onto the recording medium 30A onto the recording medium 30A through the action of heat and pressure.

[0338] As the fixing mechanism 26 , a known fixing device, for example, a heat roller fixing device, an oven fixing device, etc. can be mentioned.

[0339] Specifically, for example, the fixing mechanism 26 may be a known fixing mechanism including a fixing roller or a fixing belt as the fixing member 26A and a pressure roller or a pressure belt as the pressure member 26B.

[0340] Here, the recording medium 30A to which the electrostatic image developing toner image is transferred is transported along the transport path 34 and passes through the relative area (transfer area 32A) between the image retainer 12 and the transfer member 20, and then further reaches the setting position of the fixing mechanism 26 along the transport path 34, for example, by a transport member not shown in the figure, to fix the electrostatic image developing toner image on the recording medium 30A.

[0341] The recording medium 30A formed by fixing the electrostatic image developing toner image is discharged to the outside of the image forming apparatus 10 by two or more transport members (not shown). It should be noted that after the image holder 12 is de-electrified by the de-electrification mechanism 24, it is recharged to the charging potential by the charging mechanism 15.

[0342] [Operation of Image Forming Apparatus]

[0343] An example of the operation of the image forming apparatus 10 according to this embodiment will be described. It should be noted that various operations of the image forming apparatus 10 are performed by a control program executed by the control unit 36 .

[0344] The image forming operation of the image forming apparatus 10 will be described.

[0345] First, the surface of the image holder 12 is charged by the charging mechanism 15. The latent image forming mechanism 16 exposes the charged surface of the image holder 12 based on image information. This forms an electrostatic image corresponding to the image information on the image holder 12. The developing mechanism 18 develops the electrostatic image formed on the surface of the image holder 12 using a developer containing a specific electrostatic image developing toner. This forms an electrostatic image developing toner image on the surface of the image holder 12.

[0346] The electrostatic image developing toner image formed on the surface of the image holding member 12 is transferred to the recording medium 30A by the transfer mechanism 31 . The electrostatic image developing toner image transferred to the recording medium 30A is fixed by the fixing mechanism 26 .

[0347] On the other hand, the surface of the image holding member 12 to which the electrostatic image developing toner image has been transferred is cleaned (sweeped) by the cleaning blade 220 of the cleaning mechanism 22 , and then is de-electrified by the de-electrification mechanism 24 .

[0348] [Electrostatic image developer]

[0349] The image forming apparatus of the present embodiment preferably includes an electrostatic image developer containing an electrostatic image developing toner.

[0350] The electrostatic image developer used in this embodiment may be a one-component developer containing only a toner, or a two-component developer containing a toner and a carrier.

[0351] [Toner for electrostatic image development]

[0352] The electrostatic image developing toner used in this embodiment contains toner particles and silica particles, wherein the silica particles have a number average particle size of not less than 110 nm and not more than 130 nm, a large diameter side number particle size distribution index (upper side GSDp) of less than 1.080, an average circularity of not less than 0.94 and not more than 0.98, and a proportion of particles with a circularity of not less than 0.92 of not less than 80%.

[0353] Furthermore, the electrostatic image developing toner used in the present embodiment may further contain inorganic oxide particles, lubricant particles, and external additives other than the inorganic oxide particles and lubricant particles, as needed.

[0354] (Toner particles)

[0355] The toner particles contain, for example, a binder resin and, if necessary, a colorant, a release agent, and other additives.

[0356] - Adhesive resin -

[0357] Examples of the adhesive resin include vinyl resins formed from homopolymers of the following monomers or copolymers formed by combining two or more of these monomers: styrenes (e.g., styrene, p-chlorostyrene, α-methylstyrene, etc.), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g., ethylene, propylene, butadiene, etc.), and the like.

[0358] Examples of the adhesive resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin; mixtures of these resins with the above-mentioned vinyl resins; and graft polymers obtained by polymerizing vinyl monomers in the presence of these resins.

[0359] The adhesive resin may be used alone or in combination of two or more.

[0360] (1) Styrene acrylic resin

[0361] As the adhesive resin, a styrene acrylic resin is suitable.

[0362] Styrene acrylic resins are copolymers formed by copolymerizing at least a styrene monomer (a monomer having a styrene skeleton) and a (meth)acrylic monomer (a monomer having a (meth)acryloyl group, preferably a monomer having a (meth)acryloyloxy group). Styrene acrylic resins include, for example, copolymers of styrene monomers and the aforementioned (meth)acrylate monomers. It should be noted that the acrylic resin portion of a styrene acrylic resin is a partial structure formed by the polymerization of either or both acrylic and methacrylic monomers. Furthermore, the term "(meth)acrylic acid" encompasses both "acrylic acid" and "methacrylic acid."

[0363] Specific examples of the styrene-based monomers include styrene, alkyl-substituted styrenes (e.g., α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrenes (e.g., 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), and vinylnaphthalene. The styrene-based monomers may be used alone or in combination of two or more.

[0364] Among these, styrene is preferred as the styrene-based monomer from the viewpoints of easiness of reaction, easiness of reaction control, and availability.

[0365] Examples of the (meth)acrylic acid monomer include, specifically, (meth)acrylic acid and (meth)acrylic acid esters. Examples of the (meth)acrylic acid esters include, for example, (meth)acrylic acid alkyl esters (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isoamyl (meth)acrylate, pentyl (meth)acrylate, neopentyl (meth)acrylate, (meth)acrylate). The (meth)acrylic acid monomers may be selected from the group consisting of isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, etc.), aryl (meth)acrylates (for example, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, tert-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, etc.), dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, β-carboxyethyl (meth)acrylate, and (meth)acrylamide. The (meth)acrylic acid monomers may be used alone or in combination of two or more.

[0366] Among (meth)acrylic acid monomers, (meth)acrylates having an alkyl group with 2 to 14 carbon atoms (preferably 2 to 10 carbon atoms, more preferably 3 to 8 carbon atoms) are preferred from the perspective of improving the fixing properties of the toner. Among them, n-butyl (meth)acrylate is preferred, and n-butyl acrylate is particularly preferred.

[0367] The copolymerization ratio of the styrene-based monomer to the (meth)acrylic-based monomer (based on mass, styrene-based monomer / (meth)acrylic-based monomer) is not particularly limited, but is preferably 85 / 15 to 60 / 40.

[0368] The styrene acrylic resin preferably has a cross-linked structure. Examples of the styrene acrylic resin having a cross-linked structure preferably include a resin obtained by copolymerizing at least a styrene-based monomer, a (meth)acrylic-based monomer, and a cross-linking monomer.

[0369] Examples of the crosslinkable monomer include bifunctional or higher-functional crosslinking agents.

[0370] Examples of bifunctional crosslinking agents include divinylbenzene, divinylnaphthalene, di(meth)acrylate compounds (e.g., diethylene glycol di(meth)acrylate, methylenebis(meth)acrylamide, decanediol diacrylate, glycidyl(meth)acrylate, etc.), polyester di(meth)acrylates, and 2-([1'-methylpropyleneamino]carboxyamino)ethyl methacrylate.

[0371] Examples of trifunctional or higher-functional crosslinking agents include tri(meth)acrylate compounds (e.g., pentaerythritol tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.), tetra(meth)acrylate compounds (e.g., pentaerythritol tetra(meth)acrylate, oligoesters (meth)acrylate, etc.), 2,2-bis(4-methacryloyloxy, polyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, and diallyl chlorendic acid.

[0372] Among them, as the crosslinking monomer, from the viewpoint of improving the fixing property of the toner, a (meth)acrylate compound having two or more functional groups is preferred, a difunctional (meth)acrylate compound is more preferred, a difunctional (meth)acrylate compound having an alkylene group having 6 to 20 carbon atoms is further preferred, and a difunctional (meth)acrylate compound having a linear alkylene group having 6 to 20 carbon atoms is particularly preferred.

[0373] The copolymerization ratio of the cross-linkable monomer to all monomers (weight basis, cross-linkable monomer / all monomers) is not particularly limited, but is preferably 2 / 1,000 to 20 / 1,000.

[0374] The glass transition temperature (Tg) of the styrene acrylic resin is preferably 40° C. or higher and 75° C. or lower, and more preferably 50° C. or higher and 65° C. or lower, from the viewpoint of improving the fixing property of the toner.

[0375] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, by the "extrapolated glass transition onset temperature" method described in the glass transition temperature determination method in JIS K 7121-1987, "Plastics - Determination of Transition Temperatures."

[0376] From the viewpoint of storage stability of the toner, the weight average molecular weight of the styrene acrylic resin is preferably 5,000 to 200,000, more preferably 10,000 to 100,000, and particularly preferably 20,000 to 80,000.

[0377] The method for preparing the styrene acrylic resin is not particularly limited, and various polymerization methods (e.g., solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.) can be applied. In addition, the polymerization reaction can be applied by known operations (e.g., batch, semi-continuous, continuous, etc.).

[0378] (2) Polyester resin

[0379] As the adhesive resin, polyester resin is preferred.

[0380] Examples of the polyester resin include known amorphous (non-crystalline) polyester resins. Among the polyester resins, an amorphous polyester resin and a crystalline polyester resin may be used in combination. The crystalline polyester resin may be used in an amount of 2% by mass to 40% by mass (preferably 2% by mass to 20% by mass) relative to the total binder resin.

[0381] It should be noted that the "crystallinity" of a resin means that there is no step-like change in endothermic value in differential scanning calorimetry (DSC) and that there is a clear endothermic peak. Specifically, it means that the half-value width of the endothermic peak is within 10°C when measured at a heating rate of 10 (°C / min).

[0382] On the other hand, the "amorphous" nature of a resin means that the half-value width is larger than 10°C, the resin exhibits a step-like change in endothermic value, or no clear endothermic peak is observed.

[0383] Amorphous polyester resin

[0384] Examples of the amorphous polyester resin include polycondensates of polycarboxylic acids and polyols. A commercially available amorphous polyester resin may be used, or a synthetic amorphous polyester resin may be used.

[0385] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid), anhydrides thereof, and lower (e.g., C1-5) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids.

[0386] Among the polycarboxylic acids, dicarboxylic acids and trivalent or higher carboxylic acids having a crosslinked structure or a branched structure may be used in combination. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., C1-5) alkyl esters.

[0387] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0388] Examples of the polyol include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A). Among these, aromatic diols and alicyclic diols are preferred, and aromatic diols are more preferred.

[0389] As the polyol, a diol may be used in combination with a trivalent or higher polyol having a cross-linked structure or a branched structure. Examples of the trivalent or higher polyol include glycerin, trimethylolpropane, and pentaerythritol.

[0390] The polyols may be used alone or in combination of two or more.

[0391] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower.

[0392] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, by the "extrapolated glass transition onset temperature" method described in the glass transition temperature determination method in JIS K7121:1987 "Plastics - Determination of Transition Temperatures."

[0393] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000.

[0394] The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 to 100,000.

[0395] The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0396] It should be noted that the weight average molecular weight and number average molecular weight were measured by gel permeation chromatography (GPC). In the molecular weight measurement using GPC, a Tosoh GPC HLC-8120GPC was used as the measuring apparatus, a Tosoh TSKgel SuperHM-M (15 cm) column was used, and tetrahydrofuran (THF) was used as the solvent for measurement. The weight average molecular weight and number average molecular weight were calculated based on the measurement results using a molecular weight calibration curve prepared using a monodisperse polystyrene standard sample.

[0397] The amorphous polyester resin is obtained by a known production method. Specifically, for example, the polymerization temperature is set at 180° C. to 230° C., and the pressure in the reaction system is reduced as needed to allow the reaction to proceed while removing water or alcohol generated during condensation.

[0398] It should be noted that if the raw material monomers are insoluble or incompatible at the reaction temperature, a high-boiling-point solvent may be added as a dissolution aid to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. In the presence of monomers with poor compatibility, the monomers with poor compatibility may be condensed with a specific acid or alcohol that is polycondensed with the monomers before polycondensation with the main component.

[0399] Crystalline polyester resin

[0400] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. As the crystalline polyester resin, a commercially available product may be used, or a synthetic product may be used.

[0401] Here, in order to facilitate the formation of a crystal structure of the crystalline polyester resin, a polycondensate obtained by using a linear aliphatic polymerizable monomer is preferred over a polycondensate obtained by using a polymerizable monomer having an aromatic group.

[0402] Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, or lower (e.g., carbon number 1 to 5) alkyl esters thereof.

[0403] Among polycarboxylic acids, dicarboxylic acids may be used in combination with trivalent or higher carboxylic acids having a crosslinked structure or a branched structure. Examples of trivalent carboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., C1-5) alkyl esters.

[0404] As the polycarboxylic acid, these dicarboxylic acids can be used in combination with a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond.

[0405] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0406] Examples of the polyol include aliphatic diols (e.g., linear aliphatic diols having a main chain portion with 7 to 20 carbon atoms). Examples of the aliphatic diol include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred.

[0407] Among the polyols, diols may be used in combination with trivalent or higher-valent alcohols having a cross-linked structure or a branched structure. Examples of the trivalent or higher-valent alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0408] The polyols may be used alone or in combination of two or more.

[0409] Here, the content of the aliphatic diol in the polyol is preferably 80 mol% or more, preferably 90 mol% or more.

[0410] The melting temperature of the crystalline polyester resin is preferably 50°C to 100°C, more preferably 55°C to 90°C, and even more preferably 60°C to 85°C.

[0411] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) using the “melting peak temperature” described in the melting temperature measurement method of JIS K7121:1987 “Plastics - Determination of Transition Temperatures”.

[0412] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0413] The crystalline polyester resin can be obtained, for example, by a known production method similar to the amorphous polyester.

[0414] The content of the binder resin is, for example, preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and even more preferably 60% by mass to 85% by mass, based on the entire toner particles.

[0415] -Colorant-

[0416] Examples of the colorant include carbon black, chrome yellow, Hansa yellow, benzidine yellow, vat yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, sulfur-resistant orange, Vochug red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont Oil Red, pyrazolone red, litho red, rhodamine B lake, lake red C, pigment red, rose red, aniline blue, ultramarine blue, soluble blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate, and various other pigments; or acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, nigrosine-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes.

[0417] The coloring agents may be used alone or in combination of two or more.

[0418] The colorant may be a colorant that has been subjected to surface treatment as needed, or may be used in combination with a dispersant.

[0419] The content of the colorant is, for example, preferably from 1 mass % to 30 mass % both inclusive, and more preferably from 3 mass % to 15 mass % both inclusive, based on the entire toner particles.

[0420] -Release agent-

[0421] Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but the release agent is not limited thereto.

[0422] -Release agent-

[0423] Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but the release agent is not limited thereto.

[0424] The melting temperature of the release agent is preferably 50°C to 110°C, more preferably 60°C to 100°C.

[0425] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) using the “melting peak temperature” described in the melting temperature measurement method of JIS K7121:1987 “Plastics - Determination of Transition Temperatures”.

[0426] The content of the release agent is, for example, preferably from 1 mass % to 20 mass % inclusive, and more preferably from 5 mass % to 15 mass % inclusive, based on the entire toner particles.

[0427] -Other additives-

[0428] Examples of other additives include known additives such as magnetic materials, charge control agents, and inorganic powders. These additives may be contained in the toner particles as internal additives.

[0429] - Characteristics of toner particles, etc. -

[0430] The toner particles may be toner particles of a single-layer structure, or may be toner particles of a so-called core-shell structure composed of a core (core particle) and a coating layer (shell layer) covering the core.

[0431] Here, the toner particles having a core-shell structure may be composed of, for example, a core portion containing a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer containing a binder resin.

[0432] The volume average particle diameter (D50v) of the toner particles is preferably from 2 μm to 10 μm, and more preferably from 4 μm to 8 μm.

[0433] Incidentally, various average particle diameters and various particle size distribution indices of the toner particles were measured using Coulter Multisizer II (manufactured by Beckman Coulter) and ISOTON-II (manufactured by Beckman Coulter) for the electrolyte.

[0434] During measurement, 0.5 mg to 50 mg of the measurement sample is added to 2 ml of a 5% by mass aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant, and this is added to 100 ml to 150 ml of the electrolyte.

[0435] The electrolyte solution containing the suspended sample was dispersed using an ultrasonic disperser for 1 minute, and the particle size distribution of particles with a diameter of 2 μm to 60 μm was measured using a Coulter Multisizer II with an aperture of 100 μm. 50,000 particles were sampled.

[0436] Relative to the particle size range (interval) divided based on the measured particle size distribution, the volume and number are respectively drawn as cumulative distributions starting from the smaller diameter side, the particle size at the cumulative 16% point is defined as the volume particle size D16v and the number particle size D16p, the particle size at the cumulative 50% point is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size at the cumulative 84% point is defined as the volume particle size D84v and the number particle size D84p.

[0437] Using these values, the volume particle size distribution index (GSDv) is calculated as (D84v / D16v) 1 / 2 Calculate the particle size distribution index (GSDp) by (D84p / D16p) 1 / 2 Calculated.

[0438] The average circularity of the toner particles is preferably from 0.94 to 1.00, and more preferably from 0.95 to 0.98.

[0439] The average circularity of the toner particles is expressed as (equivalent circular circumference) / (circumference) [(circumference of a circle having the same projected area as the particle image) / (circumference of the particle projected image)]. Specifically, it is a value measured by the following method.

[0440] First, the toner particles to be measured were collected by suction and formed into a flat stream. This stream was then momentarily flashed to obtain a still image of the particles. This image was then analyzed using a flow particle image analyzer (FPIA-3000, manufactured by Sysmex) to determine the average circularity. The number of samples used to determine the average circularity was 3,500.

[0441] In the case where the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant and then subjected to ultrasonic treatment to obtain toner particles from which the external additive is removed.

[0442] (First Silica Particles)

[0443] The toner used in this embodiment contains silica particles (hereinafter also referred to as "first silica particles") having a number average particle size of not less than 110 nm and not more than 130 nm, a large diameter side number particle size distribution index (upper side GSDp) of less than 1.080, an average circularity of not less than 0.94 and not more than 0.98, and a proportion of not less than 80% by number of particles having a circularity of not less than 0.92.

[0444] The image forming apparatus of this embodiment stores a toner containing first silica particles as an external additive, and thus has excellent ability to suppress external additive filming on an image holding member.

[0445] The number average particle size of the first silica particles is 110 nm to 130 nm, and from the viewpoint of suppressing image defects in the obtained image, is preferably 113 nm to 127 nm, and more preferably 115 nm to 125 nm.

[0446] The method for making the number average particle size of the first silica particles fall within the above range is not particularly limited, and examples thereof include: for example, when the first silica particles are sol-gel silica particles, a method of adjusting the temperature or reaction time when mixing the alkali catalyst and tetraalkoxysilane in the production of the sol-gel silica particles; a method of adjusting the concentrations of the above-mentioned alkali catalyst and tetraalkoxysilane; and the like.

[0447] The large-diameter number size distribution index (upper GSDp) of the first silica particles is less than 1.080, and is preferably 1.077 or less, and more preferably less than 1.075, from the viewpoint of suppressing image defects in the obtained image.

[0448] From the viewpoint of suppressing image defects in the obtained image, the smaller diameter side number size distribution index (lower GSDp) of the first silica particles is preferably less than 1.080, more preferably 1.075 or less.

[0449] The method for making the upper side GSDp and the lower side GSDp in the first silica particles fall within the above-mentioned range is not particularly limited, and examples thereof include: for example, when the first silica particles are sol-gel silica particles, a method of adjusting the temperature or reaction time when mixing the alkali catalyst and tetraalkoxysilane in the production of the sol-gel silica particles; a method of adjusting the concentrations of the above-mentioned alkali catalyst and tetraalkoxysilane; and the like.

[0450] The number average particle size, upper GSDp, and lower GSDp of the first silica particles are determined as follows.

[0451] (1) The toner is dispersed in methanol, stirred at room temperature (23°C), and then treated in an ultrasonic bath to separate the external additive from the toner. The toner particles are then centrifuged to settle, and the dispersion containing the external additive is recovered. The methanol is then distilled off to remove the external additive.

[0452] (2) The external additives were dispersed in resin particles (polyester, weight-average molecular weight Mw=50,000) having a volume average particle size of 100 μm.

[0453] (3) An energy dispersive X-ray analyzer (EDX) (manufactured by Horiba, Ltd., EMAX Evolution X-Max 80mm) was used. 2 The resin particles dispersed with the external additive were observed using a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi High-Technologies Co., Ltd.), capturing images at 40,000x magnification. EDX analysis was performed to select at least 300 primary silica particles within a single field of view based on the presence of Si. SEM observation was performed at an accelerating voltage of 15 kV, an emission current of 20 μA, and a working distance (WD) of 15 mm. The EDX analysis was performed under these conditions for a detection time of 60 minutes.

[0454] (4) The obtained image was introduced into an image analyzer (LUZEXIII, manufactured by NIRECO Corporation), and the area of each particle was determined by image analysis.

[0455] (5) The particle size of silica is calculated as the equivalent circle diameter from the measured area value.

[0456] (6) 100 silica particles with an equivalent circle diameter of 80 nm or more were sorted out.

[0457] The cumulative distribution of the equivalent circle diameters of the separated silica particles is plotted from the smaller diameter side, and the particle diameter at the cumulative 50% point is defined as the number average particle diameter of the first silica particles.

[0458] For the silica particles separated above, the cumulative distribution of equivalent circle diameters was plotted from the small diameter side. The particle size at the 16% cumulative point was defined as the number particle size D16p, the particle size at the 50% cumulative point was defined as the number average particle size D50p, and the particle size at the 84% cumulative point was defined as the number particle size D84p. In addition, the large diameter side number particle size distribution index (upper GSDp) was calculated as (D84p / D50p). 1 / 2 Calculate the particle size distribution index on the small diameter side (lower side GSDp) by (D50p / D16p) 1 / 2 Calculated.

[0459] The average circularity of the first silica particles is 0.94 to 0.98, and is preferably 0.945 to 0.975, and more preferably 0.950 to 0.970, from the viewpoint of suppressing image defects in the obtained image.

[0460] The method for making the average circularity of the first silica particles fall within the above range is not particularly limited, and examples thereof include: for example, when the first silica particles are sol-gel silica particles, a method of adjusting the temperature or reaction time when mixing the alkali catalyst and tetraalkoxysilane in the production of the sol-gel silica particles; a method of adjusting the concentration of the above-mentioned alkali catalyst; and the like.

[0461] The proportion of silica particles having a circularity of 0.92 or greater in the first silica particles is 80% by number or greater, preferably 85% by number or greater, and more preferably 87% by number or greater, from the perspective of suppressing image defects in the obtained image.

[0462] The method for bringing the proportion of silica particles having a roundness of 0.92 or greater in the first silica particles into the above range is not particularly limited, and examples thereof include: for example, when the first silica particles are sol-gel silica particles, a method of adjusting the temperature or reaction time when mixing the alkali catalyst with tetraalkoxysilane during the production of the sol-gel silica particles; a method of adjusting the concentration of the alkali catalyst; and the like.

[0463] The average circularity of the first silica particles and the ratio of silica particles having a circularity of 0.92 or greater in the first silica particles were determined as follows.

[0464] The circularity of the 100 particles sorted by the method for determining the number average particle size of the first silica particles was calculated using the following formula (1). The 50% circularity obtained by accumulating the obtained circularity from the smaller diameter side was taken as the average circularity of the first silica particles.

[0465] Formula (1): roundness = 4π × (A / I 2 )

[0466] In formula (1), I represents the perimeter of the primary particle on the image, and A represents the projected area of the primary particle.

[0467] Furthermore, the ratio of the number of silica particles having a circularity of 0.92 or greater among 100 particles when the average circularity is calculated is defined as the number ratio of silica particles having a circularity of 0.92 or greater in the first silica particles.

[0468] From the perspective of suppressing image defects in the obtained image, the hydrophobization degree of the first silica particles is preferably 50% to 80%, more preferably 50% to 75%, and even more preferably 50% to 70%.

[0469] The method for bringing the hydrophobization degree of the first silica particles into the above-mentioned range is not particularly limited, and examples thereof include: for example, when the first silica particles are sol-gel silica particles, a method in which the surface of the silica particles is hydrophobized using a hydrophobizing agent in the presence of supercritical carbon dioxide during the production of the sol-gel silica particles is mentioned.

[0470] The hydrophobization degree of the first silica particles is determined as follows.

[0471] 0.2% by mass of silica particles as a sample were added to 50 ml of ion-exchanged water. Methanol was then added dropwise from a burette while stirring with a magnetic stirrer. The methanol mass fraction (%) in the methanol-ion-exchanged water mixed solution, at the titration endpoint where the entire sample had settled into the solution (= amount of methanol added / (amount of methanol added + amount of ion-exchanged water)), was calculated as the degree of hydrophobization (%).

[0472] The first silica particles may be particles containing silicon dioxide, i.e., SiO2, as the main component, and may be either crystalline or amorphous. The first silica particles may be particles produced using silicon compounds such as water glass and alkoxysilane as raw materials, or may be particles obtained by crushing quartz. Examples of the first silica particles include: sol-gel silica particles; aqueous colloidal silica particles; alcoholic silica particles; fumed silica particles obtained by a gas phase method; fused silica particles; and the like. Of the above, the first silica particles preferably include sol-gel silica particles.

[0473] Sol-gel silica particles can be obtained, for example, by the following method. Tetraalkoxysilane (TMOS, etc.) is dropwise added to an alkaline catalyst solution containing an alcohol compound and aqueous ammonia to hydrolyze and condense the tetraalkoxysilane, thereby obtaining a suspension containing sol-gel silica particles. The solvent is then removed from the suspension to obtain granules. The granules are then dried to obtain sol-gel silica particles.

[0474] The first silica particles may be silica particles subjected to a hydrophobic treatment using a hydrophobic treatment agent.

[0475] As the hydrophobizing treatment agent, for example, known organosilicon compounds with alkyl groups (such as methyl, ethyl, propyl, butyl, etc.) can be enumerated, and specific examples can include alkoxysilane compounds, siloxane compounds, silazane compounds, etc. Among the above, the hydrophobizing treatment agent preferably includes at least one of siloxane compounds and silazane compounds. The hydrophobizing treatment agent can be used alone or in combination with two or more.

[0476] Examples of the siloxane compound include silicone oil and silicone resin. Preferably, the silicone oil includes dimethyl silicone oil. The siloxane compound may be used alone or in combination of two or more.

[0477] Examples of the silazane compound include hexamethyldisilazane and tetramethyldisilazane. Of the above, the silazane compound preferably includes hexamethyldisilazane (HMDS). The silazane compound may be used alone or in combination of two or more.

[0478] The surface adhesion amount of the hydrophobizing agent such as the silazane compound attached to the surface of the first silica particles is preferably from 0.01% by mass to 5% by mass relative to the first silica particles, more preferably from 0.05% by mass to 3% by mass, and even more preferably from 0.10% by mass to 2% by mass, from the perspective of increasing the hydrophobization degree of the first silica particles.

[0479] As a method for hydrophobizing the first silica particles using a hydrophobizing agent, for example, there can be mentioned: a method of dissolving the hydrophobizing agent in supercritical carbon dioxide using supercritical carbon dioxide, thereby causing the hydrophobizing agent to adhere to the surface of the silica particles; a method of applying (e.g., spraying or coating) a solution containing a hydrophobizing agent and a solvent in which the hydrophobizing agent is dissolved to the surface of the silica particles in the atmosphere, thereby causing the hydrophobizing agent to adhere to the surface of the silica particles; a method of adding and maintaining a solution containing a hydrophobizing agent and a solvent in which the hydrophobizing agent is dissolved in the atmosphere to a silica particle dispersion, and then drying the mixed solution of the silica particle dispersion and the above solution.

[0480] <Other additives>

[0481] The toner used in this embodiment may further contain other external additives (hereinafter also referred to as "other external additives") in addition to the first silica particles. Examples of other external additives include inorganic oxide particles. Examples of inorganic oxide particles include SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4. Among the above, the inorganic oxide particles preferably include TiO2 and SiO2, i.e., titanium dioxide particles or silica particles (hereinafter also referred to as "second silica particles").

[0482] From the perspective of improving toner fluidity, the number average particle size of the inorganic oxide particles is preferably 9 nm to 50 nm, more preferably 10 nm to 40 nm, and even more preferably 10 nm to 30 nm.

[0483] The number average particle size of the inorganic oxide particles is determined as follows.

[0484] (1) The toner is dispersed in methanol, stirred at room temperature (23°C), and then treated in an ultrasonic bath to separate the external additive from the toner. The toner particles are then centrifuged to settle, and the dispersion containing the external additive is recovered. The methanol is then distilled off to remove the external additive.

[0485] (2) The external additives were dispersed in resin particles (polyester, weight-average molecular weight Mw=50,000) having a volume average particle size of 100 μm.

[0486] (3) An energy dispersive X-ray analyzer (EDX) (manufactured by Horiba, Ltd., EMAX Evolution X-Max 80mm) was used. 2 The resin particles dispersed with the external additive were observed using a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi High-Technologies Corporation), and images were captured at 40,000x magnification. EDX analysis was then performed to select at least 300 primary inorganic oxide particles within a field of view based on the presence of atoms (such as Si and Ti) contained in each inorganic oxide particle. SEM observation was performed at an accelerating voltage of 15 kV, an emission current of 20 μA, and a working distance (WD) of 15 mm. The EDX analysis was performed under these conditions for a detection time of 60 minutes.

[0487] (4) The obtained image was introduced into an image analyzer (LUZEXIII, manufactured by NIRECO Corporation), and the area of each particle was determined by image analysis.

[0488] (5) The particle size of each inorganic oxide particle is determined as an equivalent circle diameter from the measured area value.

[0489] (6) 100 particles with an equivalent circular diameter less than 80 nm were sorted out.

[0490] The cumulative distribution of the equivalent circle diameters of the particles thus sorted is plotted from the smaller diameter side, and the particle diameter at the cumulative 50% point is defined as the number average particle diameter of the inorganic oxide particles.

[0491] From the perspective of suppressing image defects in the resulting image, the content of the inorganic oxide particles in the toner is preferably less than the content of the first silica particles in the toner. More specifically, the content of the inorganic oxide particles is preferably from 20 parts by mass to 80 parts by mass, and more preferably from 30 parts by mass to 70 parts by mass, relative to 100 parts by mass of the first silica particles in the toner.

[0492] From the perspective of image defect suppression in the obtained image, the ratio (Da / Db) of the number average particle size Da (nm) of the first silica particles to the number average particle size Db (nm) of the inorganic oxide particles is preferably 2.0 or more and 20 or less, more preferably 2.1 or more and 32 or less, and even more preferably 2.2 or more and 30 or less.

[0493] The surface of the inorganic oxide particles as an external additive can be subjected to a hydrophobizing treatment. The hydrophobizing treatment is carried out by, for example, immersing the inorganic oxide particles in a hydrophobizing treatment agent. The hydrophobizing treatment agent is not particularly limited, and for example, a silane coupling agent, silicone oil, titanate coupling agent, aluminum coupling agent, etc. can be cited. They can be used alone or in combination of two or more.

[0494] The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the inorganic oxide particles.

[0495] Examples of the external additives include resin particles (polystyrene, polymethyl methacrylate (PMMA), melamine resin, and other resin particles), detergent active agents (for example, particles of a fluorine-based high molecular weight body), and the like.

[0496] The amount of other external additives added is, for example, preferably from 0.01% by mass to 5% by mass, and more preferably from 0.01% by mass to 2.0% by mass, based on the toner particles.

[0497] (Toner Manufacturing Method)

[0498] Next, a method for producing the toner used in this embodiment will be described.

[0499] The toner used in this embodiment is obtained by adding an external additive to the toner particles after producing the toner particles.

[0500] Toner particles can be produced by any of dry methods (such as kneading and pulverization) or wet methods (such as aggregation and coalescence, suspension polymerization, and dissolution suspension). The method for producing toner particles is not particularly limited to these methods, and a known method can be used.

[0501] The toner in this embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. Mixing can be performed using, for example, a V blender, a Henschel mixer, or a Loedige mixer. Furthermore, if necessary, coarse toner particles can be removed using a vibrating screen or a pneumatic screen.

[0502] [Carrier]

[0503] The carrier is not particularly limited, and known carriers may be used. Examples of the carrier include: a coated carrier in which a core material composed of magnetic powder is coated with a coating resin; a magnetic powder-dispersed carrier in which magnetic powder is dispersed and mixed in a matrix resin; and a resin-impregnated carrier in which porous magnetic powder is impregnated with a resin.

[0504] Note that the magnetic powder dispersed carrier and the resin impregnated carrier may be a carrier having constituent particles of the carrier as a core material and the surface of which is coated with a coating resin.

[0505] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0506] Examples of the coating resin and the base resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymers, styrene-acrylate copolymers, straight silicone resins containing organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenolic resins, epoxy resins, etc. The coating resin and the base resin may contain conductive particles and other additives.

[0507] Examples of the conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0508] When the surface of the core material is coated with a coating resin, a coating method using a coating layer forming solution obtained by dissolving the coating resin and, if necessary, various additives in an appropriate solvent can be cited. The solvent is not particularly limited and can be selected by considering the coating resin used, coating suitability, etc. Specific resin coating methods include: an immersion method in which the core material is immersed in the coating layer forming solution; a spray method in which the coating layer forming solution is sprayed onto the surface of the core material; a fluidized bed method in which the coating layer forming solution is sprayed while the core material is suspended by flowing air; a kneading coater method in which the core material of the carrier is mixed with the coating layer forming solution in a kneading coater and the solvent is removed thereafter; and the like.

[0509] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner:carrier=1:100 to 30:100, more preferably 3:100 to 20:100.

[0510] <Processing cartridge>

[0511] The process cartridge according to this embodiment will be described.

[0512] A process cartridge according to this embodiment includes: a developing mechanism that stores an electrostatic image developer containing an electrostatic image developing toner and develops an electrostatic image formed on a surface of an image holder into an electrostatic image developing toner image using the electrostatic image developer; and a cleaning mechanism that removes residual toner on the image holder. The cleaning mechanism includes either mechanism A or mechanism B. Mechanism A includes a cleaning blade that contacts the surface of the image holder, wherein a JIS-A hardness of a portion of the cleaning blade that contacts the image holder is 90 degrees or greater. Mechanism B includes a cleaning blade that contacts the surface of the image holder, wherein a contact load of the cleaning blade with the image holder is controlled by a constant load method. The electrostatic image developing toner includes toner particles and silica particles. The silica particles have a number average particle size of 110 nm to 130 nm, a large diameter side number particle size distribution index (upper GSDp) of less than 1.080, an average circularity of 0.94 to 0.98, and a proportion of particles having a circularity of 0.92 or greater of 80% by number or greater.

[0513] The preferred embodiments of the electrostatic image developing toner, electrostatic image developer, developing mechanism and cleaning mechanism in the processing box of this embodiment are respectively the same as the preferred embodiments of the electrostatic image developing toner, electrostatic image developer, developing mechanism and cleaning mechanism in the image forming apparatus of this embodiment.

[0514] The process cartridge of the present embodiment may further include at least one selected from an image holding member, a charging mechanism, a latent image forming mechanism, a transfer mechanism, and the like, as necessary.

[0515] Preferred aspects of the image holder, charging mechanism, latent image forming mechanism, transfer mechanism, etc. are the same as those of the image forming apparatus of this embodiment.

[0516] [Example]

[0517] The following describes examples of the invention, but the present invention is not limited to the following examples. It should be noted that in the following description, "parts" and "%" are all based on mass unless otherwise specified.

[0518] -Production of the first silica particles-

[0519] (Production of Silica Particle Dispersion (1))

[0520] 300 parts of methanol and 70 parts of 10% aqueous ammonia were added to a glass reaction vessel equipped with a stirrer, a dripper, and a thermometer and mixed to obtain an alkali catalyst solution. After adjusting the alkali catalyst solution to 30°C (dropping start temperature), 185 parts of tetramethoxysilane and 50 parts of 8% aqueous ammonia were added dropwise while stirring to obtain a hydrophilic silica particle dispersion (solid content 12%). The addition time was set to 30 minutes. The obtained silica particle dispersion was then concentrated to a solid content of 40% using a rotary filter R-Fine (manufactured by Kotobuki Industry Co., Ltd.). This concentrate was designated as silica particle dispersion (1).

[0521] (Production of Silica Particle Dispersions (2) to (8) and (c1) to (c6))

[0522] In the preparation of the silica particle dispersion (1), silica particle dispersions (2) to (8) and (c1) to (c6) were prepared in the same manner as the silica particle dispersion (1), except that the conditions of the alkali catalyst solution (amount of methanol, concentration and amount of ammonia water) and the conditions for generating silica particles (amount of tetramethoxysilane (TMOS) in the alkali catalyst solution, concentration and total amount of ammonia water added, and time for adding TMOS and ammonia water and temperature at the start of addition) were changed according to Table 1.

[0523] (Production of Surface-treated Silica Particles (S1))

[0524] The silica particles were surface-treated with a siloxane compound using the silica particle dispersion (1) in a supercritical carbon dioxide atmosphere as follows. The surface treatment was performed using an apparatus equipped with a carbon dioxide storage bottle, a carbon dioxide pump, an entrainer pump, an autoclave (500 ml capacity) equipped with a stirrer, and a pressure valve.

[0525] First, 300 parts of the silica particle dispersion (1) were placed in an autoclave (500 ml capacity) equipped with a stirrer, and the stirrer was rotated at 100 rpm (revolutions per minute). Liquefied carbon dioxide was then injected into the autoclave, and the temperature was raised using a heater and the pressure was simultaneously increased using a carbon dioxide pump, so that the autoclave reached a supercritical state of 150° C. and 15 MPa. While maintaining the pressure in the autoclave at 15 MPa using a pressure valve, supercritical carbon dioxide was circulated by a carbon dioxide pump to remove methanol and water from the silica particle dispersion (1) (solvent removal step), thereby obtaining silica particles (untreated silica particles).

[0526] Next, when the amount of supercritical carbon dioxide (accumulated amount: measured based on the amount of carbon dioxide in a standard state) reached 900 parts, the flow of supercritical carbon dioxide was stopped.

[0527] Subsequently, a heater maintained the temperature at 150°C and a carbon dioxide pump maintained the pressure at 15 MPa, maintaining a supercritical carbon dioxide state within the autoclave. In this state, an entrainer pump was used to inject a treatment solution into the autoclave. This treatment solution was prepared by dissolving 0.3 parts of dimethyl silicone oil (DSO: trade name "KF-96 (Shin-Etsu Chemical Co., Ltd.") with a viscosity of 10,000 cSt, a siloxane compound, in 20 parts of hexamethyldisilazane (HMDS; manufactured by Organic Synthetic Chemicals Co., Ltd.), a hydrophobizing agent, per 100 parts of the aforementioned silica particles (untreated silica particles). The reaction was then stirred at 180°C for 20 minutes. Supercritical carbon dioxide was then recirculated to remove any excess treatment solution. Stirring was then stopped, the pressure in the autoclave was released to atmospheric pressure by opening the pressure valve, and the temperature was lowered to room temperature (25°C).

[0528] The solvent removal step and the surface treatment with HMDS and DSO were sequentially performed in this manner to obtain surface-treated silica particles (S1).

[0529] (Manufacturing of Surface-treated Silica Particles (S2) to (S8) and (cS1) to (cS6))

[0530] Surface-treated silica particles (S2) to (S8) and (cS1) to (cS6) were obtained in the same manner as in the preparation of the surface-treated silica particles (S1).

[0531] (Manufacturing of Surface-treated Silica Particles (cS7))

[0532] Surface-treated silica particles (cS7) were obtained in the same manner as in paragraphs 0051 to 0053 of JP-A-2008-174430.

[0533] (Manufacturing of Surface-treated Silica Particles (cS8))

[0534] Surface-treated silica particles (cS8) were obtained in the same manner as in paragraph 0019 of JP-A-2001-194824.

[0535] [Table 1]

[0536]

[0537] -Preparation of Polyester Resin Particle Dispersion-

[0538] (Production of Amorphous Polyester Resin Particle Dispersion (A1))

[0539] Terephthalic acid: 70 parts

[0540] Fumaric acid: 30 parts

[0541] Ethylene glycol: 45 parts

[0542] 1,5-Pentanediol: 46 parts

[0543] The above materials were placed in a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column. The temperature was raised to 220°C over 1 hour under a nitrogen stream. One part of tetraethoxytitanium was added to 100 parts of the total of the above materials. While distilling off the generated water, the temperature was raised to 240°C over 0.5 hours. After a dehydration condensation reaction was continued at this temperature for 1 hour, the reaction mixture was cooled. This produced a polyester resin with a weight-average molecular weight of 9500 and a glass transition temperature of 62°C.

[0544] A mixed solvent consisting of 40 parts ethyl acetate and 25 parts 2-butanol was added to a container equipped with a temperature control mechanism and a nitrogen displacement mechanism. After preparing the mixed solvent, 100 parts of a polyester resin was slowly added and dissolved. A 10% aqueous ammonia solution (equivalent to 3 times the acid value of the resin in terms of molar ratio) was then added and stirred for 30 minutes. The container was then purged with dry nitrogen, the temperature maintained at 40°C, and 400 parts of ion-exchanged water was added dropwise at a rate of 2 parts / minute to emulsify the mixture while stirring. After the addition was complete, the emulsion was returned to 25°C to obtain a resin particle dispersion containing resin particles having a volume average particle size of 200 nm. Ion-exchanged water was added to this resin particle dispersion to adjust the solids content to 20%, thereby producing an amorphous polyester resin particle dispersion (A1).

[0545] (Production of Crystalline Polyester Resin Particle Dispersion (C1))

[0546]

[0547] The above ingredients were added to a heat-dried three-necked flask. The atmosphere in the container was then inertized with nitrogen by decompression. The mixture was stirred and refluxed at 180°C for 5 hours using a mechanical stirrer. The mixture was then slowly heated to 230°C under reduced pressure and stirred for 2 hours. Once the mixture reached a viscous state, it was air-cooled to terminate the reaction and produce a crystalline polyester resin. Molecular weight measurement (polystyrene equivalent) revealed a weight-average molecular weight (Mw) of 9700 and a melting point of 78°C.

[0548] 90 parts of the obtained crystalline polyester resin, 1.8 parts of anionic surfactant NEOGEN RK (Daiichi Kogyo Seiyaku), and 210 parts of ion-exchanged water were heated to 100°C, dispersed using an ULTRA-TURRAXT50 manufactured by IKA, and then dispersed using a pressure-dispensing Gaulin homogenizer for 1 hour to prepare a crystalline polyester resin particle dispersion (C1) having a volume average particle size of 200 nm and a solid content of 20%.

[0549] -Preparation of Styrene Acrylic Resin Particle Dispersion-

[0550] (Production of Styrene Acrylic Resin Particle Dispersion (B1))

[0551]

[0552] A solution of 4 parts of anionic surfactant (DOWFAX manufactured by Dow Chemical) dissolved in 550 parts of ion-exchanged water was placed in a flask, and the mixture containing the above raw materials was added to the mixture for emulsification. While the emulsion was gently stirred for 10 minutes, 50 parts of ion-exchanged water containing 6 parts of ammonium persulfate was added. The system was then thoroughly purged with nitrogen, heated to 75°C in an oil bath, and polymerization was allowed to proceed for 30 minutes.

[0553] then,

[0554]

[0555] The mixed solution of the above raw materials was added and emulsified. The emulsion was added to the flask over 120 minutes, and emulsion polymerization was continued for 4 hours. This yielded a resin particle dispersion containing resin particles having a weight-average molecular weight of 32,000, a glass transition temperature of 53°C, and a volume-average particle size of 240 nm. Ion-exchanged water was added to the resin particle dispersion to adjust the solids content to 20%, thereby producing a styrene acrylic resin particle dispersion (B1).

[0556] (Manufacturing of Release Agent Particle Dispersion)

[0557] Paraffin wax (HNP-9, manufactured by Nippon Seira Co., Ltd.): 100 parts

[0558] Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 1 part

[0559] Ion exchange water: 350 parts

[0560] The above materials were mixed and heated to 100°C, dispersed using a homogenizer (ULTRA-TURRAXT50 manufactured by IKA), and then dispersed using a Manton Gaulin high-pressure homogenizer (manufactured by Gaulin) to obtain a release agent particle dispersion (solid content 20%) in which release agent particles with a volume average particle size of 200 nm were dispersed.

[0561] (Manufacturing of Black Particle Dispersion)

[0562] Carbon black (Regal 330, manufactured by Cabot Corporation): 50 parts

[0563] Anionic surfactant NEOGEN RK (Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts

[0564] Ion exchange water: 192.9 parts

[0565] The above components were mixed and treated at 240 MPa for 10 minutes using an Ultimaizer (manufactured by Sugino Machine Co., Ltd.) to prepare a black particle dispersion (solid content: 20%).

[0566] (Production of Toner Particles (A1))

[0567]

[0568] The above materials were placed in a round stainless steel flask, and after adding 0.1N nitric acid to adjust the pH to 3.5, an aqueous solution of polyaluminum chloride (PAC, manufactured by Oji Paper Co., Ltd.: 30% powder) (2.0 parts) dissolved in 30 parts of ion-exchanged water was added. Dispersed at 30°C using a homogenizer (ULTRA-TURRAXT 50, manufactured by IKA Co., Ltd.), the mixture was heated to 45°C in a heating oil bath and maintained until the volume average particle size reached 4.8 μm. Subsequently, 60 parts of the amorphous polyester resin particle dispersion (A1) was added and maintained for 30 minutes. After the volume average particle size reached 5.2 μm, another 60 parts of the amorphous polyester resin particle dispersion (A1) was added and maintained for 30 minutes. Subsequently, 20 parts of a 10% aqueous solution of NTA (nitrilotriacetic acid) metal salt (Chelest 70, manufactured by Chelest Co., Ltd.) was added, and the pH was adjusted to 9.0 using a 1N aqueous sodium hydroxide solution. 1.0 part of anionic surfactant (Tayca Power) was then added, and the mixture was heated to 85°C while continuing to stir and maintained for 5 hours. The mixture was then cooled to 20°C at a rate of 20°C / min, filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles (A1) having a volume average particle size of 6.0 μm.

[0569] (Manufacturing of Toner Particles (B1))

[0570]

[0571] The above components were placed in a reaction vessel equipped with a thermometer, pH meter, and stirrer. The temperature was controlled externally with a heating jacket while maintaining the temperature at 30°C and the stirring speed at 150 rpm for 30 minutes. While dispersing the mixture with a homogenizer (ULTRA-TURRAXT T50 manufactured by IKA Japan Co., Ltd.), an aqueous solution of polyaluminum chloride (PAC, manufactured by Oji Paper Co., Ltd.: 30% powder) (2.1 parts) dissolved in 100 parts of ion-exchanged water was added. The mixture was then heated to 50°C and the particle size was measured using a Coulter Multisizer II (pore size: 50 μm, manufactured by Coulter Co., Ltd.). The volume average particle size was 5.0 μm. Subsequently, 115 parts of the resin particle dispersion (1) was added to adhere the resin particles (in a shell structure) to the surface of the aggregated particles. Next, 20 parts of a 10% aqueous solution of NTA (nitrilotriacetic acid) metal salt (Chelest 70, manufactured by Chelest Co., Ltd.) was added, and the pH was adjusted to 9.0 using a 1N aqueous sodium hydroxide solution. The temperature was then raised to 91°C at a rate of 0.05°C / min and maintained at 91°C for 3 hours. The resulting toner slurry was then cooled to 85°C and held there for 1 hour. It was then cooled to 25°C to obtain a magenta toner. This slurry was further repeatedly redispersed with ion-exchanged water, filtered, and washed until the filtrate had an electrical conductivity of 20 μS / cm or less. The filtrate was then vacuum-dried in a 40°C oven for 5 hours to obtain toner particles (B1).

[0572] (Manufacturing of Toner (A1))

[0573] 100 parts of toner particles (A1), 1.5 parts of first silica particles (S1), and 0.5 parts of titanium dioxide particles having a number average particle size of 20 nm as inorganic oxide particles were mixed and mixed using a sample mill at a rotation speed of 13,000 rpm for 30 seconds. The mixture was sieved using a vibrating sieve with a mesh size of 45 μm to obtain toner (A1).

[0574] (Manufacturing of Toners (A2) to (A8) and (cA1) to (cA8))

[0575] Each toner was obtained in the same manner as in the toner (A1) except that the type of the first silica particles had the specifications shown in Table 2.

[0576] (Manufacturing of Developers (A1) to (A8) and (cA1) to (cA8))

[0577] 10 parts of each toner and 100 parts of the following resin-coated carrier were placed in a V-type blender and stirred for 20 minutes, and then sieved with a vibrating sieve with a mesh size of 212 μm to obtain a developer.

[0578]

[0579]

[0580] The above materials, excluding the ferrite particles, were mixed with glass beads (1 mm in diameter, equivalent in amount to toluene) and stirred at 1200 rpm for 30 minutes using a sand mill manufactured by Kansai Paint Co., Ltd. to obtain a dispersion. This dispersion and the ferrite particles were placed in a vacuum degassing kneader and dried under reduced pressure while stirring to obtain a resin-coated carrier.

[0581] [Table 2]

[0582]

[0583] <Production of Image Holding Body A1>

[0584] (Formation of Primer Layer)

[0585] Zinc oxide (average particle size 70 nm: manufactured by TAYCA Co., Ltd.; specific surface area 15 m 2 100 parts by mass of 1,2-dimethylbenzene (DMSO) (100 parts by mass of DMSO) and 500 parts by mass of toluene were stirred and mixed, and 1.3 parts by mass of a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. The toluene was then distilled off by vacuum distillation, and the mixture was calcined at 120°C for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent. 110 parts by mass of the surface-treated zinc oxide was stirred and mixed with 500 parts by mass of tetrahydrofuran, and a solution of 0.6 parts by mass of alizarin dissolved in 50 parts by mass of tetrahydrofuran was added, followed by stirring at 50°C for 5 hours. The zinc oxide endowed with alizarin was then filtered out by vacuum filtration and further dried under reduced pressure at 60°C to obtain zinc oxide endowed with alizarin.

[0586] 60 parts by mass of the zinc oxide to which alizarin was added, 13.5 parts by mass of a curing agent (blocked isocyanate, Sumidur 3175, manufactured by Sumitomo-Bayer Urethane Co., Ltd.), 15 parts by mass of a butyral resin (S-LECBM-1, manufactured by Sekisui Chemical Co., Ltd.) and 85 parts by mass of methyl ethyl ketone were mixed, and 38 parts by mass of the obtained mixture was mixed with 25 parts by mass of methyl ethyl ketone. Glass beads were dispersed in a sand mill for 2 hours to obtain a dispersion. To the resulting dispersion, 0.005 parts by mass of dioctyltin dilaurate and 40 parts by mass of silicone resin particles (TOSPEARL 145, manufactured by Momentive Performance Materials) were added as a catalyst to obtain a coating solution for forming a primer layer. This primer layer coating solution was applied to an aluminum substrate by dip coating and dried and cured at 170°C for 40 minutes to obtain a primer layer with a thickness of 20 μm.

[0587] (Formation of Charge Generation Layer)

[0588] A mixture of 15 parts by mass of hydroxygallium phthalocyanine (CGM-1) having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in an X-ray diffraction spectrum using Cu kα characteristic X-rays, 10 parts by mass of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts by mass of n-butyl acetate was milled using a sand mill with a diameter of 1.5 mm. The glass beads were dispersed for 4 hours. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the resulting dispersion and stirred to obtain a coating solution for forming a charge generating layer. This coating solution for forming a charge generating layer was dip-coated on the undercoat layer and dried at room temperature (25°C) to form a charge generating layer with a thickness of 0.2 μm.

[0589] (Formation of Charge Transport Layer)

[0590] 30 parts by mass of a trimethylsilane compound (1,1,1,3,3,3-hexamethyldisilazane (manufactured by Tokyo Chemical Industry Co., Ltd.)) as a hydrophobizing agent was added to 100 parts by mass of untreated (hydrophilic) silica particles "trade name: OX50 (manufacturer: AEROSIL), volume average particle size: 40 nm", and the mixture was reacted for 24 hours and then filtered to obtain hydrophobized silica particles. These were referred to as silica particles (1). The condensation rate of the silica particles (1) was 93%.

[0591] 250 parts by mass of tetrahydrofuran were added to 50 parts by mass of silica particles (1), and 25 parts by mass of 4-(2,2-diphenylethyl)-4',4"-dimethyl-triphenylamine as a charge transport material and 25 parts by mass of bisphenol Z polycarbonate resin (viscosity-average molecular weight: 30,000) as a binder resin were added while maintaining the liquid temperature at 20°C. The mixture was stirred and mixed for 12 hours to obtain a coating liquid for forming a charge transport layer.

[0592] The charge transport layer-forming coating liquid was applied onto the charge generating layer and dried at 135° C. for 40 minutes to form a charge transport layer having a thickness of 30 μm, thereby obtaining an image holding member.

[0593] (Formation of Surface Protective Layer)

[0594] A coating liquid for forming a surface protective layer was prepared by spray coating 30 parts by mass of the charge transport material compound (A-4), 0.2 parts by mass of colloidal silica (trade name: PL-1, manufactured by Fuso Chemical Industries, Ltd.), 30 parts by mass of toluene, 0.1 parts by mass of 3,5-di-tert-butyl-4-hydroxytoluene (BHT), 0.1 parts by mass of azoisobutyronitrile (10-hour half-life temperature: 65°C), and V-30 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 10-hour half-life temperature: 104°C). This coating liquid was applied to the charge transport layer by spray coating, air-dried at room temperature (25°C) for 30 minutes, and then heated from room temperature to 150°C over 30 minutes under a nitrogen flow at an oxygen concentration of 110 ppm. The mixture was further cured by heat treatment at 150°C for 30 minutes to form a surface protective layer with a thickness of 10 μm. The universal hardness of the surface protective layer measured by the above-mentioned measurement method is 200 N / mm 2 The image holding member A1 was obtained in the above manner.

[0595] [Chemistry 8]

[0596]

[0597] <Production of Cleaning Mechanism C1>

[0598] A cleaning blade was obtained by forming a urethane resin (low hardness material layer) having a JIS-A hardness of 80 degrees using a centrifugal molding machine, and then centrifugally forming a urethane resin (high hardness material layer) having a JIS-A hardness of 90 degrees thereon.

[0599] The obtained cleaning scraper is a cleaning scraper formed by a layer with a JIS-A hardness of 90 degrees or more (a layer in contact with the image retaining body) and a layer with a lower hardness than the above-mentioned layer with a JIS-A hardness of 90 degrees or more. The length from the fixed part to the front end of the cleaning scraper is 7.5 mm, the maximum thickness of the cleaning scraper is 1.8 mm, the minimum thickness of the cleaning scraper is 0.7 mm, and the thickness of the layer with a JIS-A hardness of 90 degrees or more is 0.3 mm.

[0600] The layer having a JIS-A hardness of 90 degrees or more has a JIS-A hardness of 90 degrees, and the layer having a lower hardness than the layer having a JIS-A hardness of 90 degrees or more has a JIS-A hardness of 80 degrees.

[0601] The cleaning blade was brought into contact with the surface of the image holding member at a set angle of 30 degrees and a bite depth of 0.8 mm, thereby forming a cleaning mechanism C1.

[0602] (Examples 1 to 8 and Comparative Examples 1 to 8)

[0603] As an image forming apparatus, a modified Color 1000 Press manufactured by Fuji Xerox Co., Ltd. was prepared. The developer shown in Table 3 was stored therein, and an image holder A1 as an image holder and a cleaning mechanism shown in Table 3 as a cleaning mechanism were installed. The angle (contact angle) θ between the cleaning blade and the image holder was set to 11°, and the pressing pressure N of the cleaning blade against the image holder was set to 2.5 gf / mm. 2 , and make it a constant load mode.

[0604] -evaluate-

[0605] <Image Defect Evaluation>

[0606] Using the above-mentioned evaluation machine, prints were made on A4 paper under Condition 1 (high temperature, high humidity) or Condition 2 (low temperature, low humidity) as shown below. The surface of the image holder was visually observed to confirm the presence or absence of filming, and evaluation was performed according to the following evaluation criteria. It should be noted that the amount of image defects produced under the above-mentioned conditions corresponds to the amount of filming.

[0607] <<Condition 1>>

[0608] Temperature and humidity: 25℃ / 85%

[0609] Image density: 1%

[0610] Output number: 10,000 sheets

[0611] <<Condition 2>>

[0612] Temperature and humidity: 10℃ / 10%

[0613] Image density: 20%

[0614] Output number: 10,000 sheets

[0615] <<Evaluation Criteria>>

[0616] A: No filming occurs, no image defects

[0617] B: There is slight film formation, but no problem with image quality

[0618] C: Filming occurs, and the image quality is slightly affected

[0619] D: Frequent filming, significant defects in image quality

[0620] [Table 3]

[0621]

[0622] As shown in Table 3, the image forming apparatus of the example was superior in suppressing image defects in the obtained images as compared with the image forming apparatus of the comparative example.

Claims

1. An image forming apparatus comprising: Image holding body; a latent image forming mechanism for forming an electrostatic latent image on the image holding member; a developing mechanism storing an electrostatic image developer containing an electrostatic image developing toner and developing the electrostatic latent image formed on the surface of the image holding member into an electrostatic image developing toner image using the electrostatic image developer; a transfer mechanism for transferring the toner image to a recording medium; and A cleaning mechanism for removing residual toner on the image holding member. The above cleaning mechanism has mechanism A or mechanism B, The mechanism A includes a cleaning blade that contacts the surface of the image holding member, wherein the JIS-A hardness of the portion of the cleaning blade that contacts the image holding member is 90 degrees or higher. The mechanism B includes a cleaning blade that contacts the surface of the image holding member, and the mechanism B controls the contact load of the cleaning blade with the image holding member in a constant load manner. The above-mentioned toner for electrostatic image development contains toner particles and silica particles, the number average particle size of the silica particles is greater than 110 nm and less than 130 nm, the large diameter side number particle size distribution index, i.e., the upper side GSDp, is less than 1.080, the average roundness is greater than 0.94 and less than 0.98, and the proportion of particles with a roundness of greater than 0.92 is greater than 80% by number.

2. The image forming apparatus according to claim 1, wherein The silica particles have an upper GSDp (large diameter side number size distribution index) of less than 1.

075.

3. The image forming apparatus according to claim 1 or claim 2, wherein: The silica particles have a lower GSDp, which is an index of the number size distribution on the smaller diameter side, of less than 1.

080.

4. The image forming apparatus according to claim 1 or claim 2, wherein: The average circularity of the silica particles is 0.95 or more and 0.97 or less.

5. The image forming apparatus according to claim 1 or claim 2, wherein: The cleaning blade is a laminated blade.

6. The image forming apparatus according to claim 5, wherein: The cleaning blade includes a layer having a JIS-A hardness of 90 degrees or more and a layer having a lower hardness than the layer having a JIS-A hardness of 90 degrees or more.

7. The image forming apparatus according to claim 6, wherein: In the cleaning blade, a difference in hardness between the layer having a JIS-A hardness of 90 degrees or more and the layer having a lower hardness is 15 degrees or more in JIS-A hardness.

8. The image forming apparatus according to claim 1 or claim 2, wherein: The cleaning blade having a JIS-A hardness of 90 degrees or higher at the contact portion is a cleaning blade in which the contact portion is subjected to a curing treatment.

9. The image forming apparatus according to claim 1 or claim 2, wherein: Among the silica particles, the proportion of particles having a circularity of 0.92 or greater is 85% by number or greater.

10. The image forming apparatus according to claim 1 or claim 2, wherein: The electrostatic image developing toner further includes inorganic oxide particles having a number average particle diameter of 5 nm to 50 nm.

11. The image forming apparatus according to claim 10, wherein: The ratio (Da / Db) of the number average particle diameter Da of the silica particles to the number average particle diameter Db of the inorganic oxide particles is 2.5 or more and 20 or less.

12. The image forming apparatus according to claim 1 or claim 2, wherein: The above-mentioned toner particles contain a styrene acrylic resin as a binding resin.

13. The image forming apparatus according to claim 1 or claim 2, wherein: The toner particles contain an amorphous polyester resin as a binding resin.

14. A process cartridge to be installed and removed from an image forming apparatus, comprising: a developing mechanism storing an electrostatic image developer containing an electrostatic image developing toner and developing the electrostatic latent image formed on the surface of the image holding member into an electrostatic image developing toner image using the electrostatic image developer; and A cleaning mechanism for removing residual toner on the image holding member. The above cleaning mechanism has mechanism A or mechanism B, The mechanism A includes a cleaning blade that contacts the surface of the image holding member, wherein the JIS-A hardness of the portion of the cleaning blade that contacts the image holding member is 90 degrees or higher. The mechanism B includes a cleaning blade that contacts the surface of the image holding member, and the mechanism B controls the contact load of the cleaning blade with the image holding member in a constant load manner. The above-mentioned toner for electrostatic image development contains toner particles and silica particles, the number average particle size of the silica particles is greater than 110 nm and less than 130 nm, the large diameter side number particle size distribution index, i.e., the upper side GSDp, is less than 1.080, the average roundness is greater than 0.94 and less than 0.98, and the proportion of particles with a roundness of greater than 0.92 is greater than 80% by number.

Images