Electrophotographic member and electrophotographic image forming apparatus

Abstract

To provide a member for electrophotography that is provided with a surface excellent in wear resistance and can increase the amount of electrification of toner to obtain uniform and high transfer efficiency.SOLUTION: A member for electrophotography is a member for electrophotography comprising a surface layer including at least one resin of an acrylic resin and a methacrylic resin. The surface layer further includes a positively-charged charge control agent, and a surface of the surface layer does not have a convex part with a height exceeding 15 μm caused by the charge control agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an electrophotographic member that can be used as an intermediate transfer belt in an electrophotographic image forming apparatus such as a copier or printer. The present disclosure also relates to an electrophotographic image forming apparatus. [Background technology]

[0002] In order to improve the abrasion resistance of electrophotographic members that carry toner on their surfaces, such as intermediate transfer members, Patent Document 1 discloses that an acrylic resin is contained in the surface layer that constitutes the toner carrying surface. On the other hand, in recent years, electrophotographic image forming apparatuses have been required to have electrophotographic members capable of achieving higher transfer efficiency in order to output higher quality images. One of the factors that influence transfer efficiency is the charge amount of toner. In other words, it is important to maintain high transfer efficiency by preventing a decrease in the charge amount of toner transferred onto the electrophotographic member.

[0003] Patent Document 2 discloses a seamless belt having a surface layer containing a nigrosine dye as a conductive agent to suppress uneven resistance in the seamless belt due to uneven distribution of the conductive agent. In Patent Document 2, the surface layer is mainly made of a silicone-based material. Patent Document 3 discloses a transfer belt for an image-forming device having a surface layer containing an ionizing radiation-curable acrylic compound and an oil-soluble dye. This transfer belt is said to have a small variation in the intensity of the reflected light because, even if the surface layer is made thin to prevent cracks, the light from the optical sensor is reflected by the transfer belt surface and the reflected light does not interfere. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-316371 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-133791 [Patent Document 3] Japanese Patent Application Publication No. 2018-106036 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the present inventors investigated adding a charge control agent capable of supplying negative charge to negatively charged toner to the surface layer of an electrophotographic belt. Here, paragraph

[0007] of Patent Document 3 states that nigrosine dyes used as conductive agents are less likely to aggregate in the surface layer. The present inventors discovered that nigrosine dyes function as charge control agents capable of supplying negative charge to negatively charged toner. Therefore, the present inventors attempted to incorporate nigrosine dyes into the surface layer containing an acrylic resin of an electrophotographic member. As a result, they discovered new problems: nigrosine dyes could not be sufficiently dispersed in the coating material used to form the surface layer containing acrylic resin, and convex portions due to aggregates of nigrosine dyes could form on the toner-bearing surface (outer surface) of the surface layer formed with such coating material. Furthermore, convex portions on the toner-bearing surface of an intermediate transfer belt could reduce transfer efficiency.

[0006] One aspect of the present disclosure is to provide an electrophotographic member having both high durability and excellent transfer efficiency. Another aspect of the present disclosure is to provide an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images. [Means for solving the problem]

[0007] According to one embodiment of the present disclosure, there is provided a method for manufacturing a laminated laminated laminated laminate comprising: a base layer; and a surface layer on the base layer, the surface layer including at least one of an acrylic resin and a methacrylic resin. and, An electrophotographic member comprising: the electrophotographic member has an endless belt shape, the surface layer but , a positively charged charge control agent Sara and the surface of the surface layer does not have any protrusions having a height of more than 15 μm resulting from the charge control agent. According to another embodiment of the present disclosure, there is provided an electrophotographic member comprising a base layer and a surface layer on the base layer, the surface layer containing at least one of an acrylic resin and a methacrylic resin, wherein the surface layer further contains a positively chargeable charge control agent and a compatibilizer that makes the charge control agent compatible with the resin monomer, and the surface of the surface layer does not have any protrusions having a height exceeding 15 μm that are caused by the charge control agent.According to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including the electrophotographic member. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, a toner carrier having a surface with excellent abrasion resistance and capable of increasing the charge amount of the toner is provided. As a result, an electrophotographic member capable of achieving uniform and high transfer efficiency can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of an electrophotographic member according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a schematic diagram of a stretch blow molding machine that can be used to manufacture an electrophotographic member according to one embodiment of the present disclosure. [Figure 3] 1 is a schematic diagram of an electrophotographic image forming apparatus according to one aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present inventors focused on the phenomenon in which contact between an intermediate transfer member and a toner results in a change in the charge amount of the toner due to contact charging (or frictional charging) caused by differences in their charging characteristics. They discovered that by shifting the charging characteristics of the intermediate transfer member to a more positively charged state, i.e., toward the positive side of the triboelectric series, the amount of negative charge on the toner carried by the intermediate transfer member can be increased. Therefore, they investigated incorporating a positively charged charge control agent into the surface layer of the intermediate transfer member to increase the charge amount of the negatively charged toner on the surface layer. As a result, they confirmed that the charge amount of the negatively charged toner could be increased. However, there were cases in which convex portions (hereinafter referred to as "convex defects") with a height exceeding 15 μm were generated on the surface of the surface layer due to the charge control agent. If a convex defect exists on the toner carrying surface (hereinafter also referred to as the "outer surface") of the intermediate transfer body, transfer failure may occur at the part of the convex defect in the primary transfer process of the toner image from the photosensitive body or in the secondary transfer process of the toner image from the intermediate transfer body to paper or the like, resulting in white dot-like missing spots on the electrophotographic image.

[0011] These convex defects were thought to be caused by poor compatibility between the acrylic resin monomer and the charge control agent, resulting in the formation of aggregates. Further investigation led to the addition of a compatibilizer to improve compatibility between the positively charged charge control agent and the resin monomer, resulting in the production of electrophotographic members that do not have convex defects exceeding 15 μm in height due to the charge control agent on the surface. In particular, when nigrosine is used as the charge control agent, combining it with alkylbenzenesulfonic acid or its salt as a compatibilizer provides a synergistic effect, resulting in electrophotographic members that combine excellent charging properties with high surface properties.

[0012] An electrophotographic member according to one embodiment of the present disclosure will be described in detail with reference to the drawings. 1 is a schematic cross-sectional view showing the layer structure of an intermediate transfer member (hereinafter also referred to as an "intermediate transfer belt") in the form of an endless belt according to one embodiment of the electrophotographic member of the present disclosure. The intermediate transfer member has a base layer a1 and a surface layer a2 on the base layer, the surface layer a2 containing at least one of an acrylic resin and a methacrylic resin.

[0013] <<Paint for forming surface layer>> The surface layer can be formed, for example, by forming a coating film of a paint for forming the surface layer on the surface of the base layer a1 and then curing the coating film.

[0014] <Constituents of the paint for forming the surface layer> The surface layer-forming paint for forming the surface layer contains at least one of a monomer and an oligomer of at least one resin, acrylic resin or methacrylic resin (hereinafter simply referred to as resin), and a positively charged charge control agent. Furthermore, it may contain a conductive agent, a solvent, a radical polymerization initiator, and other components as needed, within a range that satisfies the properties required for the surface layer of the present disclosure. Each component will be described below.

[0015] Monomers / Oligomers: As the resin monomer, a polyfunctional (meth)acrylic monomer that can impart excellent abrasion resistance and abrasion resistance to the surface of the surface layer can be preferably used. The (meth)acrylic monomer refers to an acrylic monomer or a methacrylic monomer. Specific examples of polyfunctional (meth)acrylic monomers include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, isocyanuric acid EO-modified di(meth)acrylate, and isocyanuric acid EO-modified tri(meth)acrylate. Among these, dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate are preferred monomers because they can impart excellent abrasion resistance to the surface layer. Furthermore, at least two monomers selected from the above group may be used in combination. Furthermore, as the resin oligomer, one obtained by polymerizing the above-mentioned monomers and having a mass average molecular weight of about 500 to 40,000 can be used.

[0016] Positively charging charge control agents: Nigrosine is an example of a positively charging charge control agent that imparts the surface layer with the property of increasing the charge amount of negative toner and has excellent compatibility with the above-mentioned monomers and oligomers. The amount added is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, per 100 parts by weight of resin. If the amount is less than this, the effect may not be sufficient. Furthermore, if the amount is more than 30 parts by weight per 100 parts by weight of resin, the properties of the resin may be impaired, and the strength of the surface layer (resin film) may be reduced.

[0017] Compatibilizer: Nigrosine is added as a positively charged charge control agent, and additives (called compatibilizers) for enhancing compatibility between the monomer and oligomer include, for example, alkylbenzenesulfonic acid or its salts. To achieve compatibility between acrylic resins containing a large amount of aliphatic moieties and nigrosine, which contains aromatic and amine groups, a structure with an aliphatic moiety and an aromatic group and a sulfonic acid group is considered suitable for compatibilization. The alkyl group of the alkylbenzenesulfonic acid preferably has 10 to 14 carbon atoms. The cationic component of the salt is preferably a sodium ion or a potassium ion. A specific example of the salt of alkylbenzenesulfonic acid is sodium linear alkylbenzenesulfonate having a structure represented by formula (1).

[0018] [ka]

[0019] In formula (1), j and k each independently represent an integer of 1 or greater, and j+k is 7 or greater and 11 or less. More specific examples include sodium decylbenzenesulfonate (c=10), sodium undecylbenzenesulfonate (c=11), sodium dodecylbenzenesulfonate (c=12), sodium tridecylbenzenesulfonate (c=13), and sodium tetradecylbenzenesulfonate (c=14). The amount of alkylbenzene sulfonic acid added should be adjusted to match the amount of nigrosine added; the more nigrosine, the more alkylbenzene sulfonic acid. The ratio of nigrosine to alkylbenzene sulfonic acid can be adjusted appropriately depending on the type of resin and other additives. If the mass of nigrosine is A and the mass of alkylbenzene sulfonic acid or its salt is B, a mass ratio of A:B of approximately 70:30 to 99:1 can sufficiently reduce small convex defects. If the ratio of alkylbenzene sulfonic acid is less than 99:1 (nigrosine:alkylbenzene sulfonic acid), the compatibilizing effect may not be fully achieved. Furthermore, adding too much compatibilizer to the resin can impair the resin's properties and reduce the strength of the resin film; therefore, a ratio of 30 parts by mass or less per 100 parts by mass of resin is preferred.

[0020] Conductive agent: The conductive agent that may be contained in the surface layer is not particularly limited, but examples include metal oxide, carbon, and conductive polymer conductive particles. Conductive particles refer to conductive substances that are incompatible with the resin matrix and form conductive paths within the matrix. While spherical particles are common, conductive particles with high aspect ratios, such as carbon nanotubes and carbon nanofibers, are also included. Specific examples include zinc antimonate particles, gallium-doped zinc oxide particles, antimony-doped tin oxide particles, indium-doped tin oxide particles, phosphorus-doped tin oxide particles, aluminum-doped zinc oxide particles, niobium-doped tin oxide particles, fluorine-doped tin oxide particles, gallium-doped tin oxide particles, Ketjen black, acetylene black, carbon nanotubes, carbon fibers, polypyrrole, and polythiophene. These conductive particles may be used alone or in combination.

[0021] solvent: A solvent is usually added to the surface layer-forming coating material to dissolve the monomer and charge control agent and adjust the viscosity so that it can be easily applied to the base layer. The solvent is not particularly limited as long as it can dissolve the acrylic monomer and charge control agent, but ketone solvents such as acetone, 2-butanone, 4-methyl-2-pentanone, and cyclohexanone are particularly preferred, as well as aromatic hydrocarbons such as benzene, toluene, and xylene, alcohols such as butanol and octanol, esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate, or mixtures thereof.

[0022] Radical polymerization initiator: Polymerization of acrylic monomers is carried out by radical polymerization. Therefore, it is preferable to add a radical polymerization initiator (hereinafter referred to as polymerization initiator) to start this polymerization. Examples of polymerization initiators include compounds that generate active radical species thermally (thermal polymerization initiators) and compounds that generate active radical species upon irradiation with radiation (light) (radiation (photo)polymerization initiators). A more preferable method involves adding a radiation (photo)polymerization initiator and polymerizing by irradiation with radiation (light).

[0023] There are no particular limitations on the radiation (photo)polymerization initiator as long as it is decomposed by irradiation with radiation (light) to generate radicals and initiate polymerization, and examples thereof include the following: Acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, benzil dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one , thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), and the like.

[0024] The amount of polymerization initiator blended is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of acrylic monomers. If the blending amount is less than 0.01 part by mass, the hardness of the cured product may be insufficient, and if it exceeds 10 parts by mass, the cured product may not be cured to the inside (lower layer side).

[0025] Other additives: If necessary, other components may be added to the coating material for forming the surface layer within a range that does not impair the effects of the present disclosure. For example, polymerization inhibitors, polymerization initiator aids, leveling agents, wettability improvers, surfactants, plasticizers, UV absorbers, antioxidants, antistatic agents, inorganic fillers, pigments, etc. may be added.

[0026] <Method for preparing paint for forming surface layer> The method for preparing the surface layer-forming coating material is not particularly limited, but it is preferable to prepare it as follows, for example. A resin monomer or oligomer, a positively charged charge control agent, a compatibilizer, a solvent, a polymerization initiator, and other components are placed in a container equipped with a stirrer in the formulation described below, and stirred at room temperature for 30 minutes, for example, to obtain the surface layer-forming coating material. The temperature and time are set within the optimum ranges as appropriate.

[0027] <Application method> The method for applying the obtained surface layer-forming coating material to the surface of the base layer of the electrophotographic member includes a conventional application method such as dip coating, spray coating, flow coating, shower coating, roll coating, and spin coating.

[0028] <Curing method> The applied coating film can be cured by heat or radiation, depending on the type of polymerization initiator contained in the coating material. The radiation is not particularly limited as long as it is actinic radiation that can impart energy sufficient to generate polymerization initiating species (radicals), and broadly includes α-rays, γ-rays, X-rays, ultraviolet (UV), visible light, electron beam (EB), and the like. Among these, ultraviolet and electron beams are preferred from the viewpoints of curing sensitivity and ease of equipment availability, with ultraviolet being particularly preferred.

[0029] <<Base layer>> The base layer is selected and used appropriately depending on the application of the electrophotographic member. When used as an intermediate transfer member, particularly an intermediate transfer belt, the base layer is preferably made of a resin material that has both flexibility and mechanical strength.

[0030] The resin used for the base layer is not particularly limited, and specific examples include polyimide (PI), polyamideimide (PAI), polypropylene (PP), polyethylene (PE), polyamide (PA), polylactic acid (PLLA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polycarbonate (PC), and fluororesin (PVdF, etc.).

[0031] The base layer may contain, as other optional components, an ionic conductive agent (e.g., a polymeric ionic conductive agent, a surfactant), a conductive polymer, an antioxidant (e.g., a hindered phenol-based, phosphorus-based, or sulfur-based), an ultraviolet absorber, an organic pigment, an inorganic pigment, a pH adjuster, a crosslinking agent, a compatibilizer, a release agent (e.g., a silicone-based or fluorine-based), a crosslinking agent, a coupling agent, a lubricant, an insulating filler (e.g., zinc oxide, barium sulfate, calcium sulfate, barium titanate, potassium titanate, strontium titanate, titanium oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, talc, mica, clay, kaolin, hydrotalcite, silica, alumina, ferrite, calcium carbonate, barium carbonate, nickel carbonate, glass powder, quartz powder, glass fiber, alumina fiber, potassium titanate fiber, or fine particles of a thermosetting resin), a conductive filler (e.g., carbon black, carbon fiber, conductive titanium oxide, conductive tin oxide, or conductive mica), or an ionic liquid.

[0032] <Base layer manufacturing method> The method for manufacturing the base layer is not particularly limited, and molding methods suitable for various resins can be used. For example, methods for molding an endless belt-shaped base layer include extrusion molding, inflation molding, blow molding, and centrifugal molding. When forming a surface layer on the surface of a base layer formed in this manner, a core is fitted inside the base layer, and then a coating liquid for the surface layer is applied and cured as described above to form the surface layer. The thickness of the base layer is preferably 10 to 500 μm, more preferably 30 to 150 μm, in order to better maintain the flexibility of the intermediate transfer belt. Furthermore, the thickness of the surface layer is preferably 0.05 to 20 μm, more preferably 0.1 to 5 μm, in order to better maintain the flexibility of the intermediate transfer belt and further improve the wear resistance of the surface. Another layer may be present between the base layer and the surface layer. An example of such another layer is an adhesion layer that improves adhesion between the base layer and the surface layer. The surface of the base layer may be subjected to a surface treatment such as a corona treatment to improve adhesion to the surface layer.

[0033] The use of the electrophotographic member is not particularly limited, but it is suitably used, for example, as an intermediate transfer member for temporarily transferring and holding a toner image, a transport transfer belt for transporting a recording material as a transfer material, etc. In particular, it can be suitably used as an intermediate transfer belt. When the electrophotographic member is used as an intermediate transfer belt, the surface specific resistivity of the electrophotographic member is 1×10 3 Ω / □ or more, 1×10 12 It is preferable that the surface resistivity is 1×10 Ω / □ or less. 3 If the surface resistivity is 1×10 Ω / □ or more, the resistance can be prevented from decreasing, the transfer electric field can be easily obtained, and the occurrence of missing images and roughness can be effectively prevented. 12 If the resistance is Ω / □ or less, it is possible to more effectively prevent the transfer voltage from increasing, and it is possible to effectively prevent the power supply from becoming larger and the cost from increasing.

[0034] <Electrophotographic image forming apparatus> An example of an electrophotographic image forming apparatus using an electrophotographic member according to one embodiment of the present disclosure as an intermediate transfer belt will be described below. As shown in Fig. 3, this electrophotographic image forming apparatus has a so-called tandem configuration in which electrophotographic stations of multiple colors are arranged side by side in the rotation direction of the intermediate transfer belt. In the following description, the reference numerals for components of yellow, magenta, cyan, and black are given suffixes Y, M, C, and k, respectively, but the suffixes may be omitted for similar components.

[0035] In FIG. 3, photosensitive drums (electrophotographic photosensitive members, image carriers) 1Y, 1M, 1C, and 1k are surrounded by charging devices 2Y, 2M, 2C, and 2k, exposure devices 3Y, 3M, 3C, and 3k, developing devices 4Y, 4M, 4C, and 4k, and an intermediate transfer belt (intermediate transfer member) 6. The photosensitive drum 1 is rotated in the direction of arrow F at a predetermined peripheral speed (process speed). The charging device 2 charges the peripheral surface of the photosensitive drum 1 to a predetermined polarity and potential (primary charging). The exposure device 3, a laser beam scanner, outputs a laser beam that is on / off modulated in response to image information input from an external device such as an image scanner or computer (not shown), scanning and exposing the charged surface of the photosensitive drum 1. This scanning and exposure forms an electrostatic latent image on the surface of the photosensitive drum 1 according to the desired image information. The developing devices 4Y, 4M, 4C, and 4k contain toner of each color component: yellow (Y), magenta (M), cyan (C), and black (k), respectively. The developing device 4 to be used is selected based on image information, and developer (toner) is developed on the surface of the photosensitive drum 1, visualizing the electrostatic latent image as a toner image. In this embodiment, a reversal development method is used, in which toner is deposited on the exposed portion of the electrostatic latent image for development. The charging device, exposure device, and developing device constitute an electrophotographic image forming means.

[0036] The intermediate transfer belt 6 is an endless belt that is disposed so as to contact the surface of the photosensitive drum 1 and is tensioned around multiple tension rollers 20, 21, and 22. The intermediate transfer belt 6 rotates in the direction of arrow G. In this embodiment, the tension roller 20 is a tension roller that controls the tension of the intermediate transfer belt 6 to a constant level, the tension roller 22 is a drive roller for the intermediate transfer belt 6, and the tension roller 21 is an opposing roller for secondary transfer. Primary transfer rollers 5Y, 5M, 5C, and 5k are disposed at primary transfer positions that face the photosensitive drum 1 across the intermediate transfer belt 6. The unfixed toner images of each color formed on the photosensitive drum 1 are electrostatically transferred sequentially onto the intermediate transfer belt 6 by applying a primary transfer bias of opposite polarity to the charge polarity of the toner to the primary transfer roller 5 from a constant voltage source or constant current source (not shown). A full-color image is then obtained on the intermediate transfer belt 6, with the unfixed toner images of four colors superimposed on top of each other. The intermediate transfer belt 6 rotates while carrying the toner images thus transferred from the photosensitive drum 1. After each rotation of the photosensitive drum 1 after the primary transfer, the surface of the photosensitive drum 1 is cleaned of any residual toner by a cleaning device 11, and the image formation process is repeated.

[0037] At the secondary transfer position of the intermediate transfer belt 6 facing the transport path of the recording material 7 serving as a recording medium, a secondary transfer roller (secondary transfer means) 9 is disposed in pressure contact with the toner image bearing surface of the intermediate transfer belt 6. At the back side of the intermediate transfer belt 6 at the secondary transfer position, a counter roller 21 is disposed, which serves as an opposing electrode to the secondary transfer roller 9 and to which a bias is applied. When the toner image on the intermediate transfer belt 6 is transferred to the recording material 7, a bias of the same polarity as the toner is applied to the counter roller 21 by a transfer bias application means 28, for example, −1000 to −3000 V, causing a current of −10 to −50 μA to flow. The transfer voltage at this time is detected by a transfer voltage detection means 29. Furthermore, downstream of the secondary transfer position, a cleaning device (belt cleaner) 12 is provided to remove toner remaining on the intermediate transfer belt 6 after the secondary transfer. The recording material 7 passes through a conveying guide 8 and is conveyed in the direction of arrow H, and is introduced into the secondary transfer position. The recording material 7 introduced into the secondary transfer position is then sandwiched and conveyed at the secondary transfer position, at which time a constant voltage bias (transfer bias) controlled to a predetermined value is applied from a secondary transfer bias application means 28 to an opposing roller 21 of the secondary transfer roller 9. By applying a transfer bias of the same polarity as the toner to the opposing roller 21, the four-color full-color image (toner image) superimposed on the intermediate transfer belt 6 at the transfer position is transferred all at once to the recording material 7, and an unfixed full-color toner image is formed on the recording material. The recording material 7 to which the toner image has been transferred is introduced into a fixing unit (not shown) and heated and fixed. [Example]

[0038] EXAMPLES The present disclosure will be specifically described below with reference to examples and comparative examples, but the present disclosure is not limited to the configurations embodied in the examples.

[0039] <<Creating an intermediate transfer member>> <Preparation of base layer> The base layer was prepared by blow molding as follows. First, using a twin-screw extruder (product name: TEX30α, manufactured by The Japan Steel Works, Ltd.), the following resin material: PET: polyethylene terephthalate (trade name: TR-8550, manufactured by Teijin Chemicals Co., Ltd.); 100 parts by mass PEEA: Polyetheresteramide (trade name: Pelestat NC6321, manufactured by Sanyo Chemical Industries, Ltd.); 20 parts by mass 2 parts by mass of lithium perchlorate (product name: Lithium Perchlorate, manufactured by Nippon Carlit Co., Ltd.) Carbon (product name: MA-100, manufactured by Mitsubishi Chemical Corporation): 1 part by mass The thermoplastic resin composition was prepared by hot-melting and kneading. The kneading temperature was adjusted to a range of 260°C or higher and 280°C or lower, and the kneading time was approximately 3 to 5 minutes. The obtained thermoplastic resin composition was pelletized and dried at a temperature of 140°C for 6 hours. The dried pelletized thermoplastic resin composition was then placed in an injection molding machine (product name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.). The cylinder temperature was set to 295°C, and the thermoplastic resin composition was injection molded into a mold temperature-controlled at 30°C to produce a preform. The obtained preform had a test tube shape with an outer diameter of 20 mm, an inner diameter of 18 mm, and a length of 150 mm.

[0040] Next, the above preform is biaxially stretched using a biaxial stretching apparatus (stretch blow molding machine) shown in Fig. 2. Before biaxial stretching, the preform 104 was placed in a heating device 107 equipped with a non-contact heater (not shown) for heating the outer and inner walls of the preform 104, and heated with the heater so that the outer surface temperature of the preform reached 120°C. Next, the heated preform 104 was placed in a blow mold 108 with the mold temperature maintained at 30°C, and stretched in the axial direction using a stretching rod 109. At the same time, air 114 adjusted to a temperature of 23°C was introduced into the preform from a blow air injection section 110 to stretch the preform 104 in the radial direction. In this way, a bottle-shaped molded product 112 was obtained. Next, the body of the obtained bottle-shaped molded product 112 was cut to obtain a base layer of a seamless conductive belt. The thickness of the base layer of this conductive belt was 70 μm. The surface resistivity of the base layer was 1.0×10 11 It was Ω / □.

[0041] <Formation of surface layer> As mentioned above in the section on coating methods, the method for producing the surface layer is not particularly limited, but in the following examples and comparative examples, dip coating was used. The base layer obtained by the above blow molding was fitted onto the outer periphery of a cylindrical mold (core), the edges were sealed, and the mold was then immersed in a container filled with the coating liquid for the surface layer (described below).The coating liquid was lifted up so that the relative speed between the liquid surface and the base layer was constant, forming a coating film of the coating liquid on the surface of the base layer. The lifting speed (the relative speed between the surface of the coating liquid and the base layer) and the solvent ratio of the coating liquid were adjusted according to the desired film thickness.

[0042] In the following examples and comparative examples, the lifting speed was set to 10 to 50 mm / sec, and the film thickness of the surface layer was adjusted to about 3 μm. The coating liquid (acrylic resin composition) was formulated according to the composition shown in Table 1. After the coating film was formed, it was dried for 1 minute in an exhausted environment at 23°C. The drying temperature and drying time were adjusted appropriately depending on the type of solvent, solvent ratio, film thickness, etc. Then, the coating film was irradiated with a UV irradiator (product name: UE06 / 81-3, manufactured by iGraphics Co., Ltd.) with an accumulated light dose of 600 mJ / cm 2 The coating was cured by irradiating it with ultraviolet light until the thickness reached 100 μm. The thickness of the resulting surface layer was 3 μm as determined by observing the cross section with an electron microscope.

[0043] <<Evaluation method>> <Charge amount of negative toner> First, 0.5 g of toner was placed on the surface of the intermediate transfer body, and then Silbon paper was placed on top of it. A 500 g iron weight with a 50 mm square cross section was placed on top of the Silbon paper and slid 200 mm back and forth 20 times to charge the toner by bringing it into contact with the intermediate transfer body. The negative toner used was magenta toner from an HP LaserJet Pro 400 color printer M451dw (manufactured by HP). Next, the charge amount of the frictionally charged toner was measured using a Model 212HS Q / mMETER (manufactured by Trek Corporation). The mass was measured using an electronic balance, and the charge amount per unit mass, Q / M (μC / g), was calculated.

[0044] <Convex defect> The positions of the convex portions (convex defects) on the surface of the obtained intermediate transfer member were visually identified, and the shapes were measured using a confocal microscope (product name: OPTELICS C130; manufactured by Lasertec Corporation). The number of convex portions (convex defects) exceeding 15 μm in height was counted per intermediate transfer member. A 10x objective lens was used with the confocal microscope, and the height difference between the peak top and the flat portion of the shape profile was taken as the height of the convex defect. Convex defects caused by factors other than the charge control agent in the surface layer, such as convex defects in the base layer, were determined by observation and analysis as appropriate and excluded from the number of defects in this evaluation.

[0045] <Image evaluation> An intermediate transfer unit was installed in an HP COLOR LASERJET CP 3525dn (product name, manufactured by HP), and a solid black image was formed to check for image voids and uniformity. Vitality (product name, manufactured by Xerox) paper was used.

[0046] [Examples 1 to 9, Comparative Examples 1 to 6] The compounding ratios of materials constituting the surface layer coating liquid for forming the surface layer used in the examples and comparative examples are shown in Table 1. A surface layer was formed on a base layer by the above-mentioned method using the materials and compounding ratios shown in Table 1, and an intermediate transfer belt was produced.

[0047] [Table 1]

[0048] The materials shown in Table 1 were as follows: Acrylic resin No. 1: Aronix M-305 (product name, manufactured by Toagosei Co., Ltd.) No. 2: Kayarad DPHA (product name, manufactured by Nippon Kayaku Co., Ltd.) No. 3: Aronix M-313 (product name, manufactured by Toagosei Co., Ltd.) Charge control agents No. 1: Nigrosine (Solvent Black 7) (product name, manufactured by Orient Chemical Industries Co., Ltd.) No. 2: TP-415 (product name, manufactured by Hodogaya Chemical Industry Co., Ltd.) Compatibilizer No. 1: Sodium alkylbenzenesulfonate (having the structure shown in formula (1) above, J + k = 10 to 13, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) No. 2: Rosin-modified resin (Arakawa Chemical Industries, Ltd.) Solvent: 2-butanone, special grade (Kishida Chemical Co., Ltd.) Photopolymerization initiator: Omnirad 907 (product name, manufactured by IGM Resins) Conductive agent: CX-410K (product name, manufactured by Nissan Chemical Co., Ltd.) Leveling agent: BYK-UV3500 (product name, manufactured by BYK-Chemie)

[0049] The intermediate transfer members prepared in the examples and comparative examples were evaluated by the methods described above. Table 2 shows the evaluation results of the examples and comparative examples.

[0050] [Table 2]

[0051] The image evaluation criteria are as follows: Rank A: No white spots are observed in the solid black image, and no density unevenness is observed. Rank B: No white spots are observed in the solid black image, but density unevenness is observed. Rank C: Many white spots are observed in the solid black image.

[0052] The intermediate transfer belts according to Examples 1 to 9, which have a surface layer containing both the charge control agent No. 1 (Nigrosine) and sodium alkylbenzene sulfonate as a compatibilizer, exhibited a large amount of charge to the negative toner, and no convex defects with a height exceeding 15 μm due to the charge control agent were observed, resulting in good image quality. Convex defects exceeding 15 μm in height, which were caused by the charge control agent, were observed on the surfaces of the intermediate transfer belts according to Comparative Examples 1 to 5. Furthermore, white spots were observed in the solid black images obtained using these intermediate transfer belts. In particular, as shown in Comparative Examples 2, 4, and 5, when the charge control agent and the compatibilizer were not appropriately combined, good compatibility of the charge control agent was not achieved, and the occurrence of convex defects exceeding 15 μm in height, which were caused by the charge control agent, could not be suppressed, resulting in poor image evaluation. The intermediate transfer member according to Comparative Example 6 did not have such convex defects, but compared to the intermediate transfer belts according to the Examples, it was unable to impart sufficient negative charge to the negative toner. As a result, the toner transferability was insufficient, and density unevenness occurred in the solid black image. [Explanation of symbols]

[0053] a1 base layer a2 surface layer

Claims

1. An electrophotographic member comprising a base layer and a surface layer on the base layer, the surface layer containing at least one of an acrylic resin and a methacrylic resin, the electrophotographic member having an endless belt shape, the surface layer further containing a positively chargeable charge control agent, and the surface of the surface layer does not have any protrusions having a height exceeding 15 μm caused by the charge control agent.

2. 2. The electrophotographic member according to claim 1, wherein said surface layer further comprises a compatibilizer that makes said charge control agent compatible with the monomer of said resin.

3. 3. The electrophotographic member of claim 2, wherein said charge control agent is nigrosine and said compatibilizer is alkylbenzene sulfonic acid or a salt thereof.

4. 4. The electrophotographic member according to claim 3, wherein the compatibilizer is a compound having a structure represented by the following formula (1): 【Chemistry 1】 (In formula (1), j and k each independently represent an integer of 1 or more, and j+k=7 to 11).

5. An electrophotographic member comprising a base layer and a surface layer on the base layer containing at least one of an acrylic resin and a methacrylic resin, wherein the surface layer further contains a positively charged charge control agent and a compatibilizer that makes the charge control agent compatibilizable with the monomer of the resin, and the surface of the surface layer does not have any protrusions having a height of more than 15 μm caused by the charge control agent.

6. An electrophotographic image forming apparatus comprising the electrophotographic member according to any one of claims 1 to 5.

7. an electrophotographic photoreceptor; an intermediate transfer member onto which an unfixed toner image formed on the electrophotographic photosensitive member is primarily transferred; a secondary transfer means for secondarily transferring the toner image transferred onto the intermediate transfer body onto a recording medium; 7. An electrophotographic image forming apparatus according to claim 6, wherein the intermediate transfer member is the electrophotographic member.

Images