Electrophotographic belt and electrophotographic image forming device

Abstract

To provide an electrophotographic belt which is free from protrusion defects caused by aggregates of fluororesin particles even when the number of carbon atoms of a fluorine unit in a comb graft polymer is reduced and offers a superior cleaning property for a prolonged period of time, and to provide an electrophotographic image forming device.SOLUTION: An electrophotographic belt is provided, comprising a base layer and a surface layer provided on the base layer, the surface layer containing a (meth)acrylic copolymer having specific constituent units in a specific mole ratio, and fluororesin particles, where the (meth) acrylic copolymer has a weight average molecular weight of 140000 to 300000.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to electrophotographic belts such as transport transfer belts and intermediate transfer belts used in electrophotographic image forming apparatuses such as copying machines and printers, and to electrophotographic image forming apparatuses having these electrophotographic belts. [Background technology]

[0002] In electrophotographic image forming apparatuses, electrophotographic belts are used as a transport / transfer belt that transports a transfer material and an intermediate transfer belt that temporarily transfers and holds a toner image. Some image forming apparatuses also use a cleaning blade made of an elastic material such as urethane rubber to clean residual toner that has not been transferred to the electrophotographic belt. In recent years, in order to compete with other printing methods, there has been a trend toward higher durability in electrophotographic image forming apparatuses from the perspective of cost reduction. This has created a need for electrophotographic belts that have excellent toner cleaning properties, even when used for an increased number of sheets.

[0003] Patent Document 1 describes a lubricant made of polytetrafluoroethylene (hereinafter also referred to as PTFE). An intermediate transfer member containing .sup.2) particles in a surface layer is disclosed. In the electrophotographic image forming apparatus disclosed in Patent Document 1, the frictional force between the surface layer of the intermediate transfer member and the cleaning blade is reduced, thereby suppressing wear of the cleaning blade. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-160231 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a fluorine-containing comb-type graft polymer is used as a dispersant to disperse fluororesin particles (PTFE particles) in the binder resin of the surface layer. Such a fluorine-containing comb-type graft polymer contains a perfluoroalkyl group.

[0006] In recent years, there has been a demand for reducing the number of carbon atoms in the perfluoroalkyl groups in fluorine-containing comb-type graft polymers in order to reduce environmental impact. However, the present inventors have recognized that reducing the number of carbon atoms in the fluorine units reduces the affinity of the fluorine-containing comb-type graft polymers with fluororesin particles, reducing the dispersibility of the fluororesin particles in the surface layer and causing the formation of fluororesin particle agglomerates. Among the convex defects resulting from fluororesin particle agglomerates as nuclei, those with a height exceeding 10 μm may cause defects in the cleaning blade that comes into contact with the electrophotographic belt. Defective areas in the cleaning blade may prevent successful removal of transfer residual toner from the electrophotographic belt, resulting in streak-like image defects.

[0007] The present disclosure is directed to an electrophotographic belt that is free from convex defects resulting from agglomerates of fluororesin particles and has excellent cleaning properties over a long period of time, even when the number of carbon atoms in the fluorine unit in the comb-type graft polymer is reduced. The present disclosure is also directed to an electrophotographic image forming apparatus equipped with the above electrophotographic belt. [Means for solving the problem]

[0008] The present disclosure provides: 1. An electrophotographic belt having a base layer and a surface layer on the base layer, The surface layer is A (meth)acrylic copolymer having a first structural unit represented by the following formula (1) and a second structural unit represented by the following formula (2): fluororesin particles, The ratio (l / m) of the number of moles l of the first structural unit to the number of moles m of the second structural unit is 0.30 to 1.00, The weight average molecular weight of the (meth)acrylic copolymer is 140,000 to 300,000. The present invention relates to an electrophotographic belt characterized by the above-mentioned. [ka] (In formula (1), R 11 represents a hydrogen atom or a methyl group, and R 12 represents a single bond or an alkylene group having 1 to 3 carbon atoms, and Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms. [ka] (In formula (2), R 21 and R 22 represents a hydrogen atom or a methyl group, and Y A1 represents an unsubstituted alkylene group, and Y B represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond; Z A represents a structure represented by the following formula (3), a cyano group, or a phenyl group, and n is an integer of 25 or more and 150 or less. [ka] (In formula (3), Z A1 represents an alkyl group having 1 to 4 carbon atoms. [Effects of the Invention]

[0009] According to at least one aspect of the present disclosure, it is possible to obtain an electrophotographic belt that has excellent toner cleaning properties over a long period of time while reducing the environmental impact. Furthermore, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus having excellent toner cleaning properties over a long period of time can be obtained. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating a surface configuration of an electrophotographic belt according to the present disclosure. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of the configuration of an intermediate transfer type image forming apparatus. [Figure 3] FIG. 2 is a schematic diagram illustrating an example of the configuration of a belt cleaning device. [Figure 4] FIG. 1 is a schematic view showing an example of a method for producing an electrophotographic belt using a stretch blow molding machine. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the upper and lower limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0012] The term "structural unit" in the polymer of the present disclosure refers to the reacted form of a monomer substance in the polymer. For example, one section of carbon-carbon bond in the main chain of a polymer formed by polymerizing a vinyl monomer is considered to be one structural unit. The vinyl monomer can be represented by the following formula (A): [ka]

[0013] In formula (A), R A represents a hydrogen atom or a methyl group, and R Brepresents an optional substituent.

[0014] As a result of investigations by the present inventors, it has been found that by making the structure of the (meth)acrylic copolymer used as a dispersant a predetermined structure, an electrophotographic belt can be obtained that exhibits excellent lubricity with a cleaning blade for a long period of time without generating convex defects nucleated by agglomerates of fluororesin particles, even when the number of carbon atoms in the perfluoroalkyl group in the fluorine unit of the (meth)acrylic copolymer is 5 or less. It has also been found that a shorter number of carbon atoms in the fluorine unit results in an intermediate transfer belt with low surface resistivity. An electrophotographic belt according to one embodiment of the present disclosure will be described in detail below, although the present disclosure is not limited to the following embodiment.

[0015] <(Meth)acrylic copolymer (dispersant)> The (meth)acrylic copolymer according to the present disclosure has a first constitutional unit represented by the following formula (1) and a second constitutional unit represented by the following formula (2). [ka] In formula (1), R 11 represents a hydrogen atom or a methyl group, and R 12 represents a single bond or an alkylene group having 1 to 3 carbon atoms, and Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms (preferably 3 to 4 carbon atoms, more preferably 4 carbon atoms).

[0016] [ka] In formula (2), R 21 and R 22 represents a hydrogen atom or a methyl group, and Y A1 represents an unsubstituted alkylene group, and Y Brepresents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond; Z A represents a structure represented by the following formula (3), a cyano group, or a phenyl group, and n is an integer of 25 or more and 150 or less.

[0017] Y A1 The number of carbon atoms is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1. Y B The number of carbon atoms is preferably 1 to 10, more preferably 1 to 8, and particularly preferably 1 to 4. n is preferably an integer of 30 to 100, and more preferably an integer of 40 to 80.

[0018] [ka] In formula (3), Z A1 represents an alkyl group having 1 to 4 carbon atoms (preferably 1 to 2 carbon atoms, more preferably 1 carbon atom). In formula (2), Y B When represents an ester bond, -Y A1 -Y B -CH2- is -Y A1 -CO-O-CH2- and -Y A1 -O-CO-CH2-, and preferably -Y A1 -CO-O-CH2-. In addition, in formula (2), Y B represents an amide bond, -Y A1 -Y B -CH2- is -Y A1 -NH-CO-CH2- and -Y A1 -CO-NH-CH2-, and preferably -Y A1 -NH-CO-CH2-. In addition, in formula (2), Y B When represents a urethane bond, -YA1 -Y B -CH2- is -Y A1 -NH-CO-O-CH2- and -Y A1 -CO-O-NH-CH2-, and preferably -Y A1 -NH-CO-O-CH2-.

[0019] In addition, -Y A1 -Y B -Y A1 -(Y A2 ) b -(Y A3 ) c -(Y A4 ) d -(Y A5 ) e -(Y A6 ) f Preferably, the compound has a structure represented by the formula: A1 represents an unsubstituted alkylene group, and Y A2 represents a methylene group substituted with at least one atom selected from the group consisting of a hydroxy group and a halogen atom, and Y A3 represents an unsubstituted alkylene group (preferably a methylene group), and Y A4 indicates an ester bond, and Y A5 represents an unsubstituted alkylene group (preferably a methylene group), and Y A6 represents an oxygen or sulfur atom (preferably a sulfur atom); b, c, d, e and f each independently represent 0 or 1;

[0020] In the formula (2), [ka] is preferably not an acidic group with a pKa of 3 or less.

[0021] Particularly preferably, -Y A1 -Y B -Y A1 -(Y A2 ) b -(Y A4 ) d -(YA5 ) e -(Y A6 ) f wherein Y A1 is a methylene group, and Y A2 is a methylene group substituted with a hydroxy group, and Y A4 is an ester bond, and Y A5 is a methylene group, and Y A6 is a sulfur atom, and b, d, e, and f are each 1.

[0022] The (meth)acrylic copolymer has a first structural unit represented by formula (1), which gives it affinity for fluororesin particles, and a second structural unit represented by formula (2), which gives it affinity for the (meth)acrylic resin, which is the binder resin of the surface layer. By appropriately controlling the ratio and molecular weight of the first and second structural units, it is possible to prevent a decrease in the dispersibility of the fluororesin particles, even when the number of carbon atoms in the perfluoro group is 5 or less, and to prevent the occurrence of convex defects nucleated by agglomerates of fluororesin particles.

[0023] In the (meth)acrylic copolymer according to the present disclosure, when the number of moles of the first structural units is l and the number of moles of the second structural units is m, the ratio of the number of moles of the first structural units l to the number of moles of the second structural units m (l / m) is 0.30 to 1.00. When l / m is 0.30 to 1.00, the dispersibility of the fluororesin is improved and the generation of aggregates can be suppressed. Preferably, l / m is 0.30 to 0.80, more preferably 0.30 to 0.40. When the ratio of the first structural unit (fluorine unit) is high (high l / m), it becomes fluororesin particles. In addition, when the ratio of the first structural unit is low, the adsorption to the binder resin increases, but the adsorption to the fluororesin particles decreases. Therefore, it is thought that by setting l / m in an appropriate range, it is possible to achieve dispersibility of the fluororesin particles.

[0024] Furthermore, the ratio of the sum of the first structural units and the second structural units to all structural units constituting the (meth)acrylic copolymer is preferably 0.8 or more by mass. For the same reasons as above, a ratio of 0.8 or more improves the dispersibility of the fluororesin and can suppress the generation of aggregates. Preferably, it is 0.9 or more, and more preferably 0.95 or more.

[0025] The weight-average molecular weight of the (meth)acrylic copolymer is 140,000 to 300,000. When the weight-average molecular weight is within the above range, the dispersibility of the fluororesin is improved and the generation of aggregates can be suppressed. It is preferably 145,000 to 270,000, and more preferably 150,000 to 250,000. This is thought to be because, as the molecular weight of the (meth)acrylic copolymer increases, it becomes possible to prevent the fluororesin particles from coming into close proximity with each other and suppress aggregation, while if the molecular weight is not too large, it is possible to suppress deterioration of compatibility with the binder resin due to polymerization of the dispersant itself and suppress crosslinking between the fluororesin particles.

[0026] To obtain the (meth)acrylic copolymer, polymerizable monomers that give the above structure after polymerization may be graft copolymerized by a known method. Specific examples of monomers that form the structural unit represented by formula (1) include 1H,1H,2H,2H-perfluorohexyl methacrylate, 1H,1H,2H,2H-perfluoroheptyl methacrylate, and 1H,1H,2H,2H-perfluorohexyl acrylate. An example of a monomer that forms the structural unit represented by formula (2) is 1,1'-azobis(1-acetoxy-1-phenylethane). Furthermore, other monomer components may be appropriately contained within a range that does not impair the effects of the present disclosure.

[0027] <Electrophotographic belt> 1 is a schematic cross-sectional view of an electrophotographic belt 5 according to an embodiment of the present disclosure. The electrophotographic belt 5 is composed of a base layer 51 and a surface layer 52 on the base layer 51.

[0028] <base layer> Examples of materials used for the base layer include thermoplastic resins such as polycarbonate, polyvinylidene fluoride (PVDF), polyethylene, polypropylene, polymethylpentene-1, polystyrene, polyamide, polysulfone, polyarylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyphenylene sulfide, polyethersulfone, polyethernitrile, thermoplastic polyimide, polyetheretherketone, thermotropic liquid crystal polymer, polyamic acid, etc. Two or more of these may also be used in combination.

[0029] A conductive material can usually be added to the base layer to impart conductivity. Examples of the conductive material include carbon-based conductive particles such as carbon black, carbon fiber, and carbon nanotubes, and inorganic conductive particles such as metal oxides such as zinc antimonate, zinc oxide, tin oxide, and titanium oxide. When used as an intermediate transfer belt, the base layer has a volume resistivity of 1×10 8 Ω cm or more 1×10 12 The surface resistivity of the base layer is preferably in the range of 1×10 8 Ω / □ or more 1×10 14 It is preferable that the resistance is in the range of Ω / □ or less. The volume resistivity and surface resistivity can be adjusted by the amount of conductive material added.

[0030] As a device for measuring the volume resistivity, a high resistance resistivity meter (trade name: Hiresta-UX (MCP-HT800), manufactured by Nitto Seiko Analytech Co., Ltd.) is used. A ring-shaped probe (product name: UR-100 (diameter of center electrode: 5.0 cm; inner diameter of outer electrode: 5.32 cm), manufactured by Nitto Seiko Analytech Co., Ltd.) was used as the surface electrode. The measurement sample was placed on the metal surface of a registration table (manufactured by Nitto Seiko Analytech Co., Ltd.), and 100 V was applied between the ring-shaped probe and the metal surface of the registration table. The value after 10 seconds was recorded as the measurement value.

[0031] The base layer can be processed by a known method for processing a thermoplastic resin or a thermosetting resin. As a method for processing a thermoplastic resin, for example, the resin composition is pelletized and molded by a known molding method such as continuous melt extrusion molding, injection molding, stretch blow molding, or inflation molding, to obtain an electrophotographic belt in the form of an endless belt.

[0032] The thickness of the base layer is, for example, 10 to 500 μm, preferably 30 to 150 μm, and more preferably 50 to 100 μm.

[0033] <Surface layer> The surface layer contains a binder resin as a binding material, a photopolymerization initiator, a conductive agent, fluororesin particles, a first constituent unit represented by the formula (1), and a second constituent unit represented by the formula (2). The dispersant may be a copolymer (comb-type graft copolymer (hereinafter also referred to as a dispersant)).

[0034] As the binder resin, styrene resin, acrylic resin, methacrylic resin, epoxy resin, polyester resin, polyether resin, silicone resin, polyvinyl butyral resin, and mixed resins thereof can be used. The binder resin is used to improve toner transferability and ensure mechanical strength. Among the above binder resins, acrylic resin or methacrylic resin is preferably used because it is possible to disperse fluororesin particles well. Hereinafter, acrylic resin and methacrylic resin will be collectively referred to as (meth)acrylic resin.

[0035] Examples of polymerizable monomers for forming the (meth)acrylic resin include the following (i) and (ii): As the polymerizable monomer, those commercially available as paints can also be used. (i) at least one acrylate selected from the group consisting of pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, alkyl acrylate, benzyl acrylate, phenyl acrylate, ethylene glycol diacrylate, and bisphenol A diacrylate; (ii) At least one methacrylate selected from the group consisting of pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, alkyl methacrylate, benzyl methacrylate, phenyl methacrylate, ethylene glycol dimethacrylate, and bisphenol A dimethacrylate. Among these, high hardness is preferable in consideration of rubbing with other members such as a photoreceptor, a cleaning blade, etc. Therefore, it is preferable to use a large amount of bifunctional or higher crosslinkable monomers in the (meth)acrylic resin to achieve higher hardness.

[0036] In addition, in order to form a (meth)acrylic resin from such a polymerizable monomer, a photopolymerization initiator is required. There is a method in which an initiator is added and polymerization is carried out using electron beams or ultraviolet rays. Examples of the photopolymerization initiator include radical-generating photopolymerization initiators such as benzophenone, thioxanthone, benzyl dimethyl ketal, α-hydroxyketone, α-hydroxyalkylphenone, α-aminoketone, α-aminoalkylphenone, monoacylphosphine oxide, bisacylphosphine oxide, hydroxybenzophenone, aminobenzophenone, titanocene, oxime ester, and oxyphenylacetic acid ester.

[0037] In order to provide the surface layer with excellent strength, the content of the binder resin in the surface layer is preferably 20% by mass or more and 70% by mass or less, more preferably 40% by mass or more and 70% by mass or less, and particularly preferably 60% by mass or more and 70% by mass or less, relative to the mass of the total solid content of the surface layer.

[0038] When using an electrophotographic belt as an intermediate transfer belt, the surface resistivity must be less than 1.0 x 10 8 Ω / □ or more, 1.0×10 12 It is preferable that the surface resistivity is in the range of 1.0×10 Ω / □ or less. 8 When the surface resistivity is Ω / □ or more, gap discharge due to an increase in electric field strength in the pre-nip portion, which is upstream of the primary transfer nip formed by the photosensitive drum as an image carrier and the electrophotographic belt, can be suppressed, and degradation of image quality can be suppressed. 12 When the surface resistivity of the electrophotographic belt is 1.0×10 or less, it is possible to suppress the occurrence of separation discharge in the post-nip portion where the electrophotographic belt and the photosensitive drum separate on the downstream side of the primary transfer nip, and it is possible to suppress the image quality defect of blank spots in the area where discharge occurs. 9 Ω / □~1.0×10 11 Ω / □ is more preferable, 3.0×10 9 Ω / □~1.0×10 10 Ω / □ is particularly preferred.

[0039] In order to adjust the surface resistivity of the surface layer of the electrophotographic belt, it is preferable to contain a conductive agent in the surface layer. The conductive agent is preferably conductive particles, and specific examples include carbon-based conductive particles such as carbon black, carbon fiber, and carbon nanotubes, and metal oxides such as zinc antimonate, zinc oxide, tin oxide, and titanium oxide. Among these, it is preferable that the conductive particles include at least one selected from the group consisting of antimony-doped tin oxide and zinc antimonate. The content of the conductive particles in the surface layer is preferably 5 to 30% by mass, more preferably 10 to 20% by mass.

[0040] The thickness of the surface layer is, for example, 0.1 to 100.0 μm, preferably 0.5 to 10.0 μm, and more preferably 1.0 to 5.0 μm.

[0041] The fluororesin particles are used to suppress wear of the surface layer and to reduce frictional resistance with the cleaning blade and the photosensitive drum. Examples of fluororesin particles include polytetrafluoroethylene (PTFE) particles, trifluorochloroethylene particles, tetrafluoroethylene hexafluoropropylene particles, vinyl fluoride particles, vinylidene fluoride particles, difluorodichloroethylene particles and copolymers thereof, fluorocarbons, etc. Two or more of these may be used in combination. Among these, polytetrafluoroethylene (PTFE) particles are preferred because the friction coefficient of the particle surface is low and the wear of the surface layer of the electrophotographic belt with other members that come into contact with the surface layer can be more effectively reduced.

[0042] The primary particle diameter of the fluororesin particles is preferably as small as possible, specifically, preferably 100 nm to 1000 nm. By setting the diameter within this range, it is possible to suppress aggregation of the fluororesin particles in the coating liquid for forming the surface layer, and to suppress instability of the coating liquid due to precipitation. The primary particle diameter of the fluororesin particles is more preferably 100 nm to 500 nm. A range of 100 nm to 200 nm is particularly preferred. Note that the primary particle size in the present disclosure is the 50% number average particle size.

[0043] The content of the fluororesin particles is preferably 10 parts by mass or more and 60 parts by mass or less, and more preferably 20 to 50 parts by mass, per 100 parts by mass of the resin component in the surface layer, from the viewpoint of sufficiently reducing the frictional force between the surface of the surface layer and a contact member such as a cleaning blade.

[0044] The comb-type graft copolymer having the first constitutional unit represented by the formula (1) and the second constitutional unit represented by the formula (2) is used to disperse the fluororesin particles in the (meth)acrylic resin in the surface layer. The comb-type graft copolymer has an affinity for fluororesin particles due to the structural unit represented by formula (1), and an affinity for the (meth)acrylic resin, which is the binder resin of the surface layer, due to the structural unit represented by formula (2).The graft copolymer, which has an affinity for the binder resin and fluororesin particles, can be used as a dispersant to disperse the fluororesin particles in the surface layer.

[0045] In the surface layer of the electrophotographic belt of the present disclosure, the content of the comb graft copolymer relative to the fluororesin particles is preferably 1 to 20 parts by mass, more preferably 5 to 10 parts by mass, per 100 parts by mass of the fluororesin particles, from the viewpoint of improving dispersibility. As a method for processing the surface layer, for example, a coating liquid is applied and molded using a known molding method such as dip coating, spray coating, flow coating, shower coating, roll coating, spin coating, or ring coating, thereby obtaining an electrophotographic belt in an endless belt shape.

[0046] Examples of other additives include filler particles, lubricants, conductive aids, curing agents, antioxidants, ultraviolet absorbers, pH adjusters, crosslinking agents, pigments, thickeners, and the like, which are known in this field.

[0047] The thickness of the electrophotographic belt is preferably 10 μm or more and 500 μm or less, particularly preferably 30 μm or more and 150 μm or less. The electrophotographic belt of the present disclosure may be used as a belt, or may be wound around or covered on a drum or roll used as an electrophotographic member.

[0048] <Electrophotographic image forming apparatus> The electrophotographic image forming apparatus according to the present disclosure includes an electrophotographic belt and a cleaning blade. The electrophotographic belt is preferably the above-described electrophotographic belt.

[0049] 2 shows an example of an image forming apparatus equipped with an electrophotographic belt according to the present disclosure as an intermediate transfer member, configured as an electrophotographic apparatus. This image forming apparatus forms a color image on a recording medium S, such as paper, supplied from a paper feed cassette 20 using four color toners represented by C, M, Y, and K, and image forming stations for each color are arranged side by side in a substantially horizontal direction. These image forming stations are provided with photosensitive drums 1c, 1m, 1y, and 1k, respectively. Here, the suffix "c," "m," "y," or "k" is added to the reference numeral to indicate which color image forming station the component to which the reference numeral belongs.

[0050] The image forming apparatus is provided with a laser scanner 3, which is a laser optical unit, from which laser beams 3c, 3m, 3y, and 3k corresponding to the image signals of each color are emitted toward the photosensitive drums 1c, 1m, 1y, and 1k, respectively. Since all the image forming stations have the same structure, the image forming station for K color will be explained here. As shown in FIG. 1, the developing device 4k includes a conductive roller 2k that is a contact charging device, a developing unit 4k, a conductive roller 8k that is a primary transfer roller, and a toner recovery blade 14k that is used to clean the photosensitive drum 1k. The developing unit 4k includes a developing roller 41k that is a developer carrier that develops the latent image on the photosensitive drum 1k, a developing container 42k that holds toner supplied to the developing roller 41k, and a developing blade 43k that regulates the amount of toner on the developing roller 41k and applies an electric charge.

[0051] The electrophotographic belt 5 is configured as an endless belt and is provided in common to the image forming stations for each color. It is stretched over a secondary transfer opposing roller 92, a tension roller 6, and a drive roller 7, and is rotated in the direction of the arrow in the figure by the drive roller 7. The electrophotographic belt 5 comes into contact with the surfaces of the photosensitive drums 1c, 1m, 1y, and 1k in succession in the section between the tension roller 6 and the drive roller 7, and is pressed against the photosensitive drums 1c, 1m, 1y, and 1k by primary transfer rollers 8c, 8m, 8y, and 8k, respectively. As a result, the toner images formed on the surfaces of the photosensitive drums 1c, 1m, 1y, and 1k are transferred to the surface of the electrophotographic belt 5, which serves as an intermediate transfer body.

[0052] A secondary transfer roller 9 is provided opposite the counter roller 92, and the electrophotographic belt 5 is pressed against the counter roller 92 by the secondary transfer roller 9. A secondary transfer voltage is applied to the secondary transfer roller 9 from a power source via a current detection circuit 10. The secondary transfer roller 9 and the counter roller 92 form a secondary transfer unit. The recording medium S passes through a nip between the electrophotographic belt 5 and the secondary transfer roller 9 at the position of the counter roller 92 via a feed roller 12 and a transport roller 13, whereby the toner image held on the outer peripheral surface of the electrophotographic belt 5 is transferred. In this way, an image is formed on the surface of the recording medium S. The recording medium S, onto which the toner image has been transferred, passes through a fixing device 15 consisting of a roller pair of a heating roller 151 and a pressure roller 152, whereby the image is fixed, and the recording medium S is discharged to a paper output tray 21.

[0053] A cleaning blade 33 is provided at the position of the tension roller 6, which contacts the outer peripheral surface of the electrophotographic belt 5. Toner that has not been transferred to the recording medium S and remains on the outer peripheral surface of the electrophotographic belt 5 is removed from the electrophotographic belt 5 and collected by a belt cleaning device 30.

[0054] Figure 3(a) is a virtual cross-sectional view illustrating the attachment position of cleaning blade 33 when cleaning blade 33, which will be described later, is not elastically deformed, and Figure 3(b) is a schematic cross-sectional view illustrating the configuration of belt cleaning device 30. The belt cleaning device 30 has a cleaning container 31 and a cleaning action section 32 provided in the cleaning container 31. The cleaning container 31 is configured as part of the frame of the intermediate transfer belt unit (not shown). The cleaning action section 32 has a cleaning blade 33 as a cleaning member and a support member 34 that supports the cleaning blade 33. The cleaning blade 33 is an elastic blade (rubber portion) made of urethane rubber (polyurethane), which is an elastic material. The support member 34 is formed of sheet metal made of plated steel (sheet metal portion). The cleaning blade 33 is adhered to the support member 34 to form the cleaning action section 32.

[0055] The cleaning blade 33 is a plate-like member having a predetermined thickness and extending in one direction. One of the two substantially perpendicular sides of the cleaning blade 33, the longitudinal side, extends in a direction substantially perpendicular to the belt conveyance direction (hereinafter also referred to as the "thrust direction"), and one end of the lateral side comes into contact with the electrophotographic belt 5. The cleaning action portion 32 is configured to be swingable. That is, the support member 34 is swingably supported via a swing shaft 36 fixed to the cleaning container 31. When the support member 34 is pressurized by a pressure spring 35 as a pressing means provided in the cleaning container 31, the cleaning action part 32 moves around the swing shaft 36, and the cleaning blade 33 is pressed against (pressed against) the electrophotographic belt 5.

[0056] Pressure springs 35 are arranged at both longitudinal ends of the support member 34, and press the cleaning blade 33 against the electrophotographic belt 5. A tension roller 6 is arranged inside the electrophotographic belt 5, facing the cleaning blade 33. The cleaning blade 33 is in contact with the electrophotographic belt 5 in the counter direction to the belt transport direction. That is, the cleaning blade 33 is in contact with the surface of the electrophotographic belt 5 with the tip of its free end in the widthwise direction facing upstream in the belt transport direction. As a result, a blade nip portion 37 is formed between the cleaning blade 33 and the electrophotographic belt 5. In the blade nip portion 37, the cleaning blade 33 scrapes toner from the surface of the moving electrophotographic belt 5.

[0057] The attachment position of the cleaning blade 33 can be set as follows. For example, the set angle θ is 24°, the penetration amount δ is 1.5 mm, and the contact pressure is 0.6 N / cm. Here, the set angle θ is the angle formed between the electrophotographic belt 5 and the cleaning blade 33. The penetration amount δ is the length in the normal direction where the free end of the cleaning blade 33 overlaps with the electrophotographic belt 5. The thickness of this cleaning blade 33 is 2 mm, the length in the thrust direction is 245 mm, and the hardness of the cleaning blade 33 is 77 degrees according to the JIS K 6253 standard. Since the length in the thrust direction of the electrophotographic belt 5 is 250 mm, the cleaning blade 33 is in contact with the electrophotographic belt 5 over the entire width.

[0058] The pressure from the cleaning blade 33 at the blade nip 39 is defined as a linear pressure in the longitudinal direction and is measured using a film-type pressure measurement system (product name: PINCH, manufactured by Nitta Corporation). By setting the temperature as described above, it is possible to suppress the cleaning blade 33 from turning over or making a slipping noise in a high-temperature, high-humidity environment (30°C / 80%), and to obtain good cleaning performance. Furthermore, by setting the temperature as described above, it is possible to suppress cleaning defects in a low-temperature, low-humidity environment (15°C / 10%), and to obtain good cleaning performance.

[0059] In addition, urethane rubber and synthetic resin generally have a large frictional resistance when sliding against each other, which can easily cause initial curling of the cleaning blade 33. Therefore, an initial lubricant such as graphite fluoride can be applied in advance to the tip of the free end of the cleaning blade 33.

[0060] The color of printed matter changes depending on conditions such as the operating environment of the image forming apparatus. Therefore, it is necessary to measure density appropriately and provide feedback to the control mechanism within the main body. The toner image for density correction is transferred to the surface of the electrophotographic belt 5, and then transported to the position of the drive roller 7 as the electrophotographic belt 5 rotates. The toner density is detected by a density detection sensor 160, located on the opposite side of the electrophotographic belt 5 from the drive roller 7. An adjustment toner image (patch image) is formed on the electrophotographic belt 5 during a period other than the period during which the toner image to be secondarily transferred to the recording material is primarily transferred onto the electrophotographic belt 5. The image formation conditions are adjusted based on the results of the measurement. [Example]

[0061] The present disclosure will be specifically described below with reference to examples and comparative examples, but the present disclosure is not limited thereto. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0062] <Synthesis of (meth)acrylic copolymer having a first structural unit represented by formula (1) and a second structural unit represented by formula (2)> In the present disclosure, a (meth)acrylic copolymer (hereinafter also referred to as a "graft copolymer") having a first structural unit represented by the formula (1) and a second structural unit represented by the formula (2) was synthesized as follows. The (meth)acrylate compounds and macromonomer compounds used in the following synthesis examples can be produced by known methods, for example, by referring to JP-A-2009-104145. Alternatively, commercially available acrylate compounds and macromonomer compounds may be used.

[0063] Specifically, for example, the (meth)acrylate compounds used in the following synthesis examples can be synthesized by reacting perfluoroalkyl iodide RfI, which is synthesized by telomerization using C2F5I as a starting material, with (meth)acrylic acid. The macromonomer compound can also be synthesized by reacting a (meth)acrylate monomer, a chain transfer agent, and a (meth)acrylate monomer having a functional group capable of bonding to the chain transfer agent (for example, glycidyl methacrylate).

[0064] (Graft copolymer A-1) 3.31 parts of 1H,1H,2H,2H-perfluorohexyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.), 180 parts of a macromonomer (number average molecular weight 6,000) represented by the following formula (M-1), 14.18 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) (trade name: OTAZO-15, Otsuka Chemical Co., Ltd.), and 900 parts of n-butyl acetate were mixed in a glass flask equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermostatic bath, and thermometer at 20°C under a nitrogen atmosphere for 30 minutes, and then the reaction mixture was heated to 85°C to 90°C and reacted for 5 hours. The reaction was stopped by cooling with ice, and 4500 parts of 2-propanol was added to obtain a precipitate. This precipitate was washed with a mixed solvent of n-butyl acetate:2-propanol=1:5 and dried at a temperature of 80° C. under reduced pressure of 1325 Pa or less for 3 hours to obtain graft copolymer A-1.

[0065] [ka]

[0066] The weight average molecular weight of each graft copolymer in the examples was measured by the following method. First, a sample was dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The resulting solution was then filtered through a solvent-resistant membrane filter "Maesholidisc" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution was adjusted so that the concentration of components soluble in THF was approximately 0.8 mass%. This sample solution was used for measurements under the following conditions.

[0067] Apparatus: HLC8120 GPC (detector: RI) (Tosoh Corporation) Column: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko K.K.) Eluent: tetrahydrofuran (THF) ·Flow rate: 1.0ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml The molecular weight of the sample was calculated using a molecular weight calibration curve prepared using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500" manufactured by Toso Corporation).

[0068] (Graft copolymer A-2) Graft copolymer A-2 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 2.81 parts of 1H,1H,2H,2H-perfluoropentyl methacrylate was used instead of 1H,1H,2H,2H-perfluorohexyl methacrylate.

[0069] (Graft copolymer A-3) Graft copolymer A-3 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 3.81 parts of 1H,1H,2H,2H-perfluorohexyl methacrylate was used instead of 1H,1H,2H,2H-perfluoroheptyl methacrylate.

[0070] (Graft copolymer A-4) Graft copolymer A-4 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 42.53 parts.

[0071] (Graft copolymer A-5) Graft copolymer A-5 was obtained in the same manner as in the synthesis example for graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 17.72 parts.

[0072] (Graft copolymer A-6) Graft copolymer A-6 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 11.70 parts.

[0073] (Graft copolymer A-7) Graft copolymer A-7 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 8.51 parts.

[0074] (Graft copolymer A-8) Graft copolymer A-8 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 7.80 parts.

[0075] (Graft copolymer A-9) Graft copolymer A-9 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 6.38 parts.

[0076] (Graft copolymer A-10) Graft copolymer A-10 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of the macromonomer represented by formula (M-1) used was changed to 240 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 17.72 parts, and the amount of n-butyl acetate used was changed to 1,200 parts.

[0077] (Graft copolymer A-11) Graft copolymer A-11 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1H,1H,2H,2H-perfluorohexyl methacrylate used was changed to 2.98 parts, the amount of the macromonomer represented by the formula (M-1) used was changed to 66 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 7.09 parts, and the amount of n-butyl acetate used was changed to 500 parts.

[0078] (Graft copolymer A-12) Graft copolymer A-12 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of the macromonomer represented by formula (M-1) used was changed to 60 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 7.09 parts, and the amount of n-butyl acetate used was changed to 500 parts.

[0079] (Graft copolymer A-13) Graft copolymer A-13 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that the amount of 1H,1H,2H,2H-perfluorohexyl methacrylate used was changed to 3.64 parts, the amount of the macromonomer represented by the formula (M-1) used was changed to 54 parts, the amount of 1,1'-azobis(1-acetoxy-1-phenylethane) used was changed to 7.09 parts, and the amount of n-butyl acetate used was changed to 500 parts.

[0080] (Graft copolymer A-14) Graft copolymer A-14 was obtained in the same manner as in the synthesis example of graft copolymer A-1, except that 3.17 parts of 1H,1H,2H,2H-perfluorohexyl acrylate was used instead of 1H,1H,2H,2H-perfluorohexyl methacrylate.

[0081] The resulting graft copolymers A-1 to A-14 were subjected to GPC measurement by the method described above, and the weight average molecular weights were calculated. The results are shown in Table 1.

[0082] [Table 1]

[0083] [Materials used in preparing coating solutions for forming surface layers according to Examples and Comparative Examples] The materials used to prepare the surface layer-forming coating liquids for the examples and comparative examples are shown in Table 2 below.

[0084] <Coating fluid materials> [Table 2]

[0085] [Preparation of Coating Solutions 1 to 15 for Forming Surface Layer] Each material was weighed out in the blending amount (mass ratio converted to solid content) shown in Table 3 below, and the materials except for the conductive agent were subjected to a basic dispersion process using a stirring homogenizer (manufactured by AS ONE Corporation). The liquid was then dispersed using a high-pressure emulsifying disperser (product name: Nanovaita, manufactured by Yoshida Kikai Kogyo Co., Ltd.) until the 50% average particle size of the contained PTFE particles reached 200 nm. The conductive particles 2 were dispersed in isopropyl alcohol to a concentration of 40 mass % to form a slurry. and used it. While stirring the conductive slurry, the liquid in which the PTFE particles had been dispersed was added dropwise to obtain a coating liquid for forming a surface layer. The particle size of the particles in the coating liquid was measured using a concentrated particle size analyzer FPAR-1000 manufactured by Otsuka Electronics based on dynamic light scattering (DLS) technology (standard ISO 22412). Ta.

[0086] [Table 3]

[0087] The structure of the (meth)acrylic copolymer contained in the surface layer can also be analyzed by the following method. <Structure of (meth)acrylic copolymer and molar ratio of constituent units> A 100mm square sample is cut from the electrophotographic belt with a cutter, and the surface of the sample (the surface of the electrophotographic belt) is placed in contact with an inorganic glass plate (150mm square, 5mm thick). A 120mm square, 500g weight is placed on top of the sample (the back side of the electrophotographic belt) and left to stand for 30 days in an environment with a temperature of 30°C and a relative humidity of 50%. After leaving the sample to stand, the glass plate surface is removed, and the surface of the glass plate is washed with methyl ethyl ketone (MEK), and the MEK used for washing is collected. The collected MEK is dried and the residue is analyzed by NMR, which makes it possible to analyze the structure of the (meth)acrylic copolymer. <Weight average molecular weight> The weight average molecular weight of the (meth)acrylic copolymer can be evaluated by evaluating the residue obtained after drying the collected MEK using GPC.

[0088] The characteristic values ​​and performance of the electrophotographic belts produced in the examples and comparative examples were evaluated according to the following [Evaluation 1] to [Evaluation 3].

[0089] [Evaluation 1] Surface resistivity evaluation The surface resistivity ρs of the electrophotographic belt was measured by the following method. The electrophotographic belt was left to stand in an environment of 23°C and 50% relative humidity for 6 hours, and then the measurement was carried out. The measuring device used was a high-resistance resistivity meter (product name: Hiresta-UX (MCP-HT800), manufactured by Nitto Seiko Analytech Co., Ltd.). A ring-shaped probe (product name: UR-100 (diameter of center electrode: 5.0 cm; inner diameter of outer electrode: 5.32 cm), manufactured by Nitto Seiko Analytech Co., Ltd.) was used as the surface electrode. The measurement sample was placed on the Teflon (registered trademark) side of a register table (manufactured by Nitto Seiko Analytech Co., Ltd.), and a voltage of 100 V was applied between the center electrode and outer electrode of the ring-shaped probe. was applied, and the value after 10 seconds was taken as the measured value. The measurement was carried out on a randomly extracted electrophotographic belt at eight points per belt, two points in the width direction and four points in the circumferential direction, and the average value was used as the representative value.

[0090] [Evaluation 2] Evaluation of convex defects The positions of the convex portions (convex defects) on the surface of the obtained electrophotographic belt were identified visually, and then the shapes were measured using a confocal microscope (trade name: OPTELICS C130; manufactured by Lasertec Corporation). The number of convex portions (convex defects) exceeding 10 μm in height was counted per electrophotographic belt, and the maximum height was used as the representative value. 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 PTFE particles in the surface layer, such as convex defects in the base layer, were appropriately determined by observation and analysis and excluded from the number of defects in this evaluation.

[0091] [Evaluation 3] Evaluation of toner cleaning performance Using an electrophotographic image forming apparatus having the configuration shown in FIG. 2, an electrophotographic belt was installed as an intermediate transfer member, and the toner cleaning performance was evaluated. This evaluation was carried out under an environment of a temperature of 15°C and a relative humidity of 10%, using OCE Extra (basis weight 80 g / m) as the recording medium S. 2 ) and JIS A4 size paper were used. The following solid white image evaluation was carried out before and after a durability test of 50,000 sheets.

[0092] After the electrophotographic belt was installed in the image forming apparatus, laser light 3y and 3m was irradiated onto the photosensitive drums 1y and 1m to record a red image (Y toner and M toner) over the entire surface of an A4 size sheet with the secondary transfer voltage turned off (0 V). Then, the secondary transfer voltage was set to an appropriate value, and 15 sheets of solid white images were continuously printed. Because the secondary transfer voltage was not applied, most of the Y toner and M toner transferred from the photosensitive drums 1y and 1m to the entire surface of the electrophotographic belt 5 was not transferred to the recording medium S at the secondary transfer section, but instead entered the cleaning blade 33. If the toner was removed from the electrophotographic belt, the next 15 sheets would be output as completely blank sheets. However, if the toner was not removed, the residual toner that slipped past the cleaning blade 33 would be transferred to the recording medium S at the secondary transfer section. In other words, the residual toner was transferred onto the blank sheet, and output as a toner cleaning failure image on the recording medium S. The presence or absence of a toner cleaning failure image was visually inspected.

[0093] Next, after printing 50,000 sheets of an image (hereinafter referred to as "E letter image") of a 4-point letter "E" on an A4-sized sheet of paper with a printing rate of 1%, a red image was printed with the secondary transfer voltage turned off as described above, and after setting the secondary transfer voltage to the appropriate output, 15 sheets of solid white images were printed to evaluate whether or not there were any images with poor toner cleaning. Furthermore, after the toner cleaning evaluation, the cleaning blade 33 was removed from the image forming apparatus, and the state of wear at the contact portion of the cleaning blade 33 with the electrophotographic belt was observed using an optical microscope (magnification: 100x). The above evaluation results were ranked according to the following criteria.

[0094] Rank A: No toner adhesion due to poor toner cleaning on the electrophotographic belt is observed in either the initial solid white image or the solid white image after durability testing. In addition, the amount of wear of the cleaning blade at the contact point with the electrophotographic belt after forming the solid white image after durability testing is less than 1 μm. Rank B: No toner adhesion due to poor toner cleaning on the electrophotographic belt is observed in either the initial solid white image or the solid white image after durability testing. On the other hand, the amount of wear of the cleaning blade at the contact point with the electrophotographic belt after forming the solid white image after durability testing is 1 μm or more. Rank C: Adhesion of toner due to insufficient toner cleaning on the electrophotographic belt is observed in both the initial solid white image and the solid white image after durability testing.

[0095] Example 1 [Base layer manufacturing] First, a thermoplastic resin composition was prepared by melt-kneading the following base layer materials in a weight ratio of PEN / PEEA / CB = 84 / 15 / 1 using a twin-screw extruder (trade name: TEX30α, manufactured by The Japan Steel Works, Ltd.). The melt-kneading temperature was adjusted to a range of 260°C to 280°C, and the melt-kneading time was 3 to 5 minutes. The obtained thermoplastic resin composition was pelletized and dried at a temperature of 140°C for 6 hours. Next, the dried pelletized thermoplastic resin composition was placed in an injection molding machine (trade name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.). The cylinder temperature was set to 295°C, and the pellets were 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 50 mm, an inner diameter of 46 mm, and a length of 100 mm.

[0096] ·Base material PEN: polyethylene naphthalate (trade name: TN-8050SC, manufactured by Teijin Chemical Co., Ltd.) PEEA: polyether ester amide (trade name: Pelestat NC6321, manufactured by Sanyo Chemical Industries, Ltd.) CB: Carbon black (product name: MA-100, manufactured by Mitsubishi Chemical Corporation)

[0097] Next, the above preform is biaxially stretched using a biaxial stretching apparatus (stretch blow molding machine) shown in Fig. 4. Before biaxial stretching, the preform 104 is 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 becomes 150°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 seamless base layer of an electrophotographic belt, which had a thickness of 70.2 μm, a circumferential length of 712.2 mm, and a width of 244.0 mm.

[0098] [Surface layer formation] The base layer obtained by blow molding was fitted onto the outer periphery of a cylindrical mold (circumference 712 mm), the edges were sealed, and the mold was then immersed in a container filled with the coating liquid 1. The mold was then pulled up so that the relative speed between the liquid surface of the curable composition and the base layer was constant, forming a coating film made of the coating liquid on the surface of the base layer. The pulling speed (the relative speed between the liquid surface of the curable composition and the base layer) and the solvent ratio of the curable composition can be adjusted depending on the desired film thickness. In this example, the pulling speed was set to 10 to 50 mm / sec, and adjusted to achieve a surface layer thickness of 3 μm. In this example, the coating direction refers to the direction opposite to the direction in which the base layer was pulled up. In other words, the location where the base layer was first pulled up from the coating liquid is the most upstream. The base layer coated with the coating liquid was then removed from the cylindrical mold and dried for 1 minute in an exhaust air environment at 23°C. The drying temperature and drying time were adjusted appropriately depending on the solvent type, solvent ratio, and film thickness. After that, the coating was irradiated with a UV irradiator (product name: UE06 / 81-3, manufactured by Eye Graphics 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 3.0 μm. The thickness of the surface layer was determined by destructive testing in which an electrophotographic belt separately prepared under the same conditions was cut and the cross section was observed with an electron microscope (product name: XL30-SFEG, manufactured by FEI). The destructive testing results showed that the thickness of the surface layer was 3.0 μm.

[0099] Examples 2 to 10 As shown in Table 4, Example 2 was prepared in the same manner as Example 1, except that surface layer-forming coating liquids 2 to 3, coating liquids 6 to 8, coating liquids 11 to 12, and coating liquids 14 to 15 were used to form the surface layers. Electrophotographic belts according to the present invention to 10 were produced and evaluated.

[0100] Table 4 shows the evaluation results of the electrophotographic belts of Examples 1 to 10. In each example, no toner cleaning defects occurred in the toner cleaning evaluation carried out after the 50,000-sheet paper feed process, but in Examples 6 and 8, the cleaning blade was worn to a depth of 1 μm or more, and Examples 6 and 8 were judged to be Rank B. Furthermore, in Examples other than Examples 6 and 8, when the vicinity of the contact point of the cleaning blade with the electrophotographic belt was observed after the test, no noticeable wear marks were found on the cleaning blade, and they were judged to be Rank A.

[0101] [Table 4]

[0102] (Comparative Examples 1 to 5) As shown in Table 5, electrophotographic belts according to Comparative Examples 1 to 5 were produced and evaluated in the same manner as in Example 1, except that surface layer-forming coating liquids 4 to 5, coating liquids 9 to 10, and coating liquid 13 were used to form the surface layers, respectively.

[0103] Table 5 shows the evaluation results of the electrophotographic belts described in Comparative Examples 1 to 5. In all the comparative examples, convex defects of 10 μm or more were confirmed in evaluation 2. In addition, in evaluation 3, in the toner cleaning evaluation after passing 50,000 sheets, toner cleaning failure occurred, and the electrophotographic belt was determined to be rank C.

[0104] [Table 5]

[0105] The present disclosure includes the following configurations. (Configuration 1) 1. An electrophotographic belt having a base layer and a surface layer on the base layer, The surface layer is A (meth)acrylic copolymer having a first structural unit represented by the following formula (1) and a second structural unit represented by the following formula (2): fluororesin particles, The ratio (l / m) of the number of moles l of the first structural unit to the number of moles m of the second structural unit is 0.30 to 1.00, The weight average molecular weight of the (meth)acrylic copolymer is 140,000 to 300,000. Electrophotographic belt characterized by: [ka] (In formula (1), R 11 represents a hydrogen atom or a methyl group, and R 12 represents a single bond or an alkylene group having 1 to 3 carbon atoms, and Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms. [ka] (In formula (2), R 21 and R 22 represents a hydrogen atom or a methyl group, and Y A1 represents an unsubstituted alkylene group, and Y B represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond; Z A represents a structure represented by the following formula (3), a cyano group, or a phenyl group, and n is an integer of 25 or more and 150 or less. [ka] (In formula (3), Z A1represents an alkyl group having 1 to 4 carbon atoms. (Configuration 2) 2. The electrophotographic belt according to claim 1, wherein Rf is a perfluoroalkyl group having 4 carbon atoms. (Configuration 3) 3. The electrophotographic belt according to claim 1, wherein the ratio of the sum of the first structural unit and the second structural unit to all structural units constituting the (meth)acrylic copolymer is 0.8 or more by mass. (Configuration 4) 4. The electrophotographic belt according to any one of Configurations 1 to 3, wherein the surface layer further contains conductive particles. (Configuration 5) 5. The electrophotographic belt according to claim 4, wherein the conductive particles include at least one selected from the group consisting of antimony-doped tin oxide and zinc antimonate. (Configuration 6) 6. The electrophotographic belt according to claim 4, wherein the content of the conductive particles in the surface layer is 5% by mass to 30% by mass. (Configuration 7) The surface resistivity of the surface layer is 1.0×10 8 Ω / □~1.0×10 12 7. The electrophotographic belt according to any one of configurations 1 to 6, wherein the resistivity is Ω / □. (Configuration 8) In the formula (2), -Y A1 -Y B -ga, -Y A1 -(Y A2 ) b -(Y A3 ) c -(Y A4 ) d -(Y A5 ) e -(Y A6 ) f 8. The electrophotographic belt according to any one of configurations 1 to 7, which has a structure represented by the following formula: (where Y A1 represents an unsubstituted alkylene group, and Y A2 represents a methylene group substituted with at least one atom selected from the group consisting of a hydroxy group and a halogen atom, and Y A3 represents an unsubstituted alkylene group, and YA4 indicates an ester bond, and Y A5 represents an unsubstituted alkylene group, and Y A6 represents an oxygen or sulfur atom, and b, c, d, e, and f each independently represent 0 or 1. (Configuration 9) An electrophotographic image forming apparatus including an electrophotographic belt and a cleaning blade, 9. An electrophotographic image forming apparatus, wherein the electrophotographic belt is the electrophotographic belt according to any one of the first to eighth aspects. [Explanation of symbols]

[0106] 1 Photosensitive drum 2 Conductive roller 3 Laser scanner 4 Developer 5 electrophotographic belt 6 tension roller 7 drive roller 8 Primary transfer roller 9 Secondary transfer roller 10 Current detection circuit 12 feeding roller 13 conveying roller 14 toner collection blade 15 Fuser unit 20 Paper feed cassette 21 Paper output tray 30 Belt cleaning device 31 Cleaning blade 41 Development roller 42 developing container 43 developing blade 51 base layer 52 surface layer 60 opening 92 secondary transfer opposing roller 151 heating roller 152 pressure roller 160 image density sensor S Recording Media

Claims

1. 1. An electrophotographic belt having a base layer and a surface layer on the base layer, The surface layer is A (meth)acrylic copolymer having a first structural unit represented by the following formula (1) and a second structural unit represented by the following formula (2): fluororesin particles, The ratio of the number of moles l of the first structural unit to the number of moles m of the second structural unit (l / m) is 0.30 to 1.00, The weight average molecular weight of the (meth)acrylic copolymer is 140,000 to 300,000. Electrophotographic belt characterized by: 【Chemical 1】 (In formula (1), R １１ represents a hydrogen atom or a methyl group, and R １２ represents a single bond or an alkylene group having 1 to 3 carbon atoms, and Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms. 【Chemistry 2】 (In formula (2), R ２１ and R ２２ represents a hydrogen atom or a methyl group, and Y Ａ１ represents an unsubstituted alkylene group, and Y Ｂ represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (—COO—), an amide bond (—NHCO—), a urethane bond (—NHCOO—), or a divalent linking group derived by combining one or more selected from these groups and bonds with —O— or —S—, or a single bond; Z Ａ represents a structure represented by the following formula (3), a cyano group, or a phenyl group, and n is an integer of 25 or more and 150 or less. 【Chemistry 3】 (In formula (3), Z Ａ１ represents an alkyl group having 1 to 4 carbon atoms.

2. 2. The electrophotographic belt according to claim 1, wherein Rf is a perfluoroalkyl group having 4 carbon atoms.

3. 2. The electrophotographic belt according to claim 1, wherein a ratio of the sum of the first structural units and the second structural units to all structural units constituting the (meth)acrylic copolymer is 0.8 or more on a mass basis.

4. 2. The electrophotographic belt of claim 1, wherein said surface layer further comprises conductive particles.

5. 5. An electrophotographic belt according to claim 4, wherein said conductive particles comprise at least one selected from the group consisting of antimony-doped tin oxide and zinc antimonate.

6. 5. The electrophotographic belt according to claim 4, wherein the content of said conductive particles in said surface layer is 5% by mass to 30% by mass.

7. The surface resistivity of the surface layer is 1.0×10 ８ Ω / □ to 1.0 x 10 １２ 2. The electrophotographic belt of claim 1, wherein the surface roughness is Ω / □.

8. In the formula (2), -Y Ａ１ -Y Ｂ -ga, -Y Ａ１ -(Y Ａ２ ) ｂ -(Y Ａ３ ) ｃ -(Y Ａ４ ) ｄ -(Y Ａ５ ) ｅ -(Y Ａ６ ) ｆ 2. The electrophotographic belt according to claim 1, which has a structure represented by the formula: (where Y Ａ１ represents an unsubstituted alkylene group, and Y Ａ２ represents a methylene group substituted with at least one atom selected from the group consisting of a hydroxy group and a halogen atom, and Y Ａ３ represents an unsubstituted alkylene group, and Y Ａ４ represents an ester bond, and Y Ａ５ represents an unsubstituted alkylene group, and Y Ａ６ represents an oxygen or sulfur atom, and b, c, d, e, and f each independently represent 0 or 1.

9. An electrophotographic image forming apparatus including an electrophotographic belt and a cleaning blade, An electrophotographic image forming apparatus, wherein the electrophotographic belt is the electrophotographic belt according to any one of claims 1 to 8.

Images