Electrophotographic tape and electrophotographic image forming equipment

Abstract

The present invention relates to an electrophotographic belt and an electrophotographic image forming apparatus. Provided is an electrophotographic belt that can suppress the occurrence of poor cleaning even when used for a long time. The electrophotographic belt includes a surface layer containing a first acrylic resin, wherein resin particles are present on the outer surface of the surface layer, wherein the resin particles each contain a second acrylic resin and a fluororesin, and wherein the second acrylic resin and the fluororesin are exposed on the outer surface of each resin particle.

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic belt such as a transport transfer belt or an intermediate transfer belt and to an electrophotographic image forming apparatus including the electrophotographic belt. Background Art

[0002] In an electrophotographic image forming apparatus, an electrophotographic belt is used as a conveying transfer belt configured to convey a recording medium serving as a transfer material, or as an intermediate transfer belt configured to temporarily hold a toner image for transfer.

[0003] In Japanese Patent Application Laid-Open No. 2004-361765, an electrophotographic image forming apparatus is disclosed in which the cleaning performance of a cleaning blade for residual toner on an intermediate transfer belt can be improved. The cleaning device of the electrophotographic image forming apparatus includes a powdery release agent coating device configured to coat a powdery release agent (specifically, zinc stearate powder) to the outer peripheral surface of the intermediate transfer belt.

[0004] According to the electrophotographic image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-361765, a release agent is continuously supplied to the intermediate transfer belt. Therefore, even when the apparatus is used for a long time, the occurrence of poor cleaning can be prevented. However, the presence of a powdered release agent coating device may be an obstacle to miniaturization and cost reduction of the electrophotographic image forming apparatus.

[0005] One aspect of the present disclosure is to provide an electrophotographic belt that can suppress the occurrence of poor cleaning even when used for a long period of time. Another aspect of the present disclosure is to provide an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. Summary of the invention

[0006] According to one aspect of the present disclosure, there is provided an electrophotographic belt including a surface layer containing a first acrylic resin, wherein resin particles are present on an outer surface of the surface layer, wherein the resin particles each contain a second acrylic resin and a fluororesin, and wherein the second acrylic resin and the fluororesin are exposed on the outer surface of each resin particle.

[0007] Furthermore, according to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including: an electrophotographic belt; and a cleaning blade abutting against an outer surface of the electrophotographic belt, wherein the electrophotographic belt is the above-described electrophotographic belt.

[0008] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1is a schematic diagram for illustrating an example of an electrophotographic belt according to an aspect of the present disclosure. Figure 1 (A) is a perspective view. Figure 1 (B) is an enlarged view of the outer surface of the surface layer of the belt, and Figure 1 (C) is an enlarged view of the resin particle portion of the outer surface.

[0010] Figure 2 is a schematic cross-sectional view for illustrating one example of the configuration of an electrophotographic image forming apparatus of an intermediate transfer system.

[0011] Figure 3 is a schematic cross-sectional view for illustrating an example of a stretch blow molding machine.

[0012] Figure 4 It is a schematic diagram for illustrating a configuration example of an imprint processing apparatus configured to form grooves in the surface of a belt for electrophotography. DETAILED DESCRIPTION

[0013] The release agent formed of metal soap or the like is easily separated from the toner carrying surface (hereinafter sometimes simply referred to as "surface") of a belt for electrophotography (hereinafter sometimes simply referred to as "belt"). That is, the release agent on the surface of the belt moves to a member in contact with the surface of the belt such as paper (transfer material), a cleaning blade, or a photosensitive member according to an operation performed accompanying image formation, thereby disappearing from the surface of the belt.

[0014] Meanwhile, for the purpose of imparting wear resistance, for example, an acrylic resin may be contained in the surface layer for forming the surface of the belt. The present inventors have found that, in the case where resin particles each containing an additional acrylic resin and a fluororesin are attached to the surface of the belt including the surface layer containing the acrylic resin, the resin particles hardly disappear from the surface even when the belt is used for a long period of time, and thus the occurrence of poor cleaning can be continuously prevented.

[0015] This is probably because of the following reasons. The acrylic resin in the surface layer and the acrylic resin in each resin particle have high affinity for each other, and the acrylic resin tends to be positively charged while the fluororesin tends to be negatively charged. Therefore, the resin particles are more firmly attached to the surface of the belt.

[0016] Furthermore, the fluorine resin has a lubricating effect. Therefore, when the resin particles are stably attached to the surface of the belt, satisfactory cleaning properties can be maintained for a long period of time.

[0017] The electrophotographic belt according to one aspect of the present disclosure is described in detail below. The present disclosure is not limited to the following aspects.

[0018] <Electronic Photography Belt and Resin Particles>

[0019] The electrophotographic belt includes a surface layer containing a first acrylic resin, typically a surface layer formed of the first acrylic resin. For example, the electrophotographic belt includes a base layer having an endless belt shape, and a surface layer provided on an outer peripheral surface of the base layer.

[0020] An elastic layer may be provided between the base layer and the surface layer. The presence of the elastic layer exhibits, for example, an effect of further improving the transferability of the toner image onto the recording material in the secondary transfer step.

[0021] Figure 1 The electrophotographic belt 5 shown in (A) has an endless belt shape. The electrophotographic belt includes a base layer 5-1 having an endless belt shape and a surface layer 5-2 formed on the outer peripheral surface of the base layer 5-1. The surface layer 5-2 contains at least a first acrylic resin.

[0022] like Figure 1 As shown in (B), resin particles 201 are present on the outer surface 202 of the electrophotographic belt. Figure 1 (C) is a schematic diagram of the surface of one of the resin particles 201. Figure 1 As shown in (C), the resin particle 201 contains the second acrylic resin 205 and the fluorine resin 204 , and the fluorine resin 204 and the second acrylic resin 205 are exposed on the outer surface of the resin particle 201 .

[0023] The first acrylic resin and the second acrylic resin in each resin particle preferably have repeating units of the same structure. Therefore, the affinity between the outer surface of the belt and the resin particles is enhanced, so that the effect of preventing the occurrence of poor cleaning can be easily maintained for a long time. In particular, the first acrylic resin and the second acrylic resin are preferably the same as each other.

[0024] In the outer surface 202 of the surface layer, it is preferred that the resin particles exist in a larger amount in both ends along the width direction of the belt 5 than in the central part along the width direction of the belt 5. Both ends of the belt deviate from the area in which the image is to be formed, and therefore the amount of toner to be supplied to the part is small. In addition, due to the deflection of the cleaning blade, the pressing pressure in each end is stronger than the pressing pressure in the central part, and therefore the friction becomes greater. Due to, for example, the fragmentation or wear of the blade, poor cleaning is more likely to occur early in the area of ​​each end portion where the friction is large compared to the area of ​​the central part where the friction is small. Therefore, when the resin particles exist in a larger amount in the two ends than in the central part, the occurrence of poor cleaning can be more continuously suppressed. A portion from one end along the width direction of the belt toward the center along the width direction of the belt up to 20 mm is adopted as the end, and a portion closer to the center relative to the end is adopted as the central part.

[0025] Furthermore, it is preferred that the outer surface 202 of the surface layer has a plurality of grooves 203 provided therein extending in the circumferential direction of the electrophotographic belt. When the grooves are provided, the friction between the belt and the cleaning blade is reduced, and thus the occurrence of cleaning failure can be more consistently suppressed.

[0026] When an observation area of ​​a predetermined size of, for example, 715 μm×535 μm is set at an arbitrary position on the outer surface 202, the ratio of the total area of ​​the resin particles 201 covering the outer surface 202 in the observation area to the area of ​​the observation area (hereinafter sometimes referred to as "particle coverage area ratio") is preferably 0.1% or more, more preferably 0.5% or more from the viewpoint of reducing the friction between the electrophotographic belt and the cleaning blade. From the viewpoint of toner transfer efficiency and image quality, the particle coverage area ratio is preferably 35% or less. When the central portion and both end portions in the width direction of the belt have different particle coverage area ratios, the particle coverage area ratios of each of the central portion and both end portions preferably fall within the above range.

[0027] The first acrylic resin and the second acrylic resin are each preferably a polymerization product of a multifunctional acrylate monomer. Therefore, friction is easily reduced, and thus the occurrence of poor cleaning can be more continuously suppressed.

[0028] As multifunctional acrylate monomer, it is possible to use, for example, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, trimethylolpropane PO modified triacrylate, trimethylolpropane EO modified triacrylate, isocyanuric acid EO modified triacrylate, ditrimethylolpropane tetraacrylate, diglycerol EO modified acrylate and bisphenol EO modified diacrylate. Here, "EO" means "ethylene oxide", and "PO" means "propylene oxide". However, the first acrylic resin and the second acrylic resin can each be a polymerized product of a monofunctional acrylate monomer, such as N-acryloyloxyethyl hexahydrophthalimide, o-phenylphenol EO modified acrylate, p-cumylphenol EO modified acrylate or nonylphenol EO modified acrylate. These first acrylic resin and the second acrylic resin can each be a homopolymer or a copolymer, or can be a mixture of multiple acrylic resins.

[0029] The fluororesin in the resin particles 201 is preferably polytetrafluoroethylene. When polytetrafluoroethylene is used, the friction between the belt and the cleaning blade is further reduced, and therefore the occurrence of poor cleaning can be suppressed more continuously. However, the fluororesin is not limited to this, and, for example, perfluoropolyether can also be used as the fluororesin. Other examples of fluororesin include polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer and ethylene-tetrafluoroethylene copolymer. The fluororesin can be a homopolymer or a copolymer, or can be a mixture of multiple fluororesins.

[0030] It is preferred that, in the resin particles 201, the content of the second acrylic resin is 24% by mass or more and 90% by mass or less, and the content of the fluororesin is 5% by mass or more and 70% by mass or less. When the content of the second acrylic resin is 24% by mass or more, the adhesion between the resin particles and the outer surface of the belt is kept satisfactory, and thus it is easy to obtain a continuous poor cleaning prevention effect. When the content of the second acrylic resin is 90% by mass or less, it is easy to reduce friction. Similarly, when the content of the fluororesin is 5% by mass or more, it is easy to reduce friction. When the content of the fluororesin is 70% by mass or less, the adhesion between the resin particles and the outer surface of the belt is kept satisfactory, and thus it is easy to obtain a continuous poor cleaning prevention effect.

[0031] The base layer having an endless belt shape can be produced by using, for example, a method comprising melt-extruding pellets of a thermoplastic resin composition into a cylindrical shape, or a known method such as injection molding, stretch blow molding, or inflation molding.

[0032] In addition, the surface layer can be formed, for example, by applying a coating for forming a surface layer to the outer peripheral surface of the base layer having an endless belt shape by using a known method such as dip coating, spray coating, flow coating, shower coating, roller coating, spin coating, or ring coating, and drying and curing the applied coating.

[0033] 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. In addition, the electrophotographic belt according to one aspect of the present disclosure may be used as a belt as it is, or may be used by winding around a drum or roller or the like used as an electrophotographic member or by covering a drum or roller or the like. The thickness of the surface layer is preferably 0.1 μm or more and 50 μm or less, particularly preferably 0.5 μm or more and 10 μm or less. When the thickness is 0.1 μm or more, it is easy to make the durability of the belt to wear satisfactory. When the thickness is 50 μm or less, it is easy to suppress the occurrence of cracks due to repeated bending of the belt.

[0034] As a method for producing resin particles, a known method can be used. For example, a method including using a ball mill, a jet mill or a pounder configured to pulverize a solid can be used. In addition, a nozzle vibration method including causing monomer molecules to react with each other in a liquid, a Shirasu porous glass (SPG) membrane emulsification method, a microchannel method, a miniemulsion polymerization method, a soap-free emulsion polymerization method, a dispersion polymerization method, or a seed emulsion polymerization method can be used.

[0035] The shape and size of the resin particles are not particularly limited as long as the particles can exhibit lubricity. However, from the viewpoint of preventing toner slipping when the resin particles are sandwiched between a cleaning blade and a belt, the shortest outer diameter of each resin particle, i.e., its short diameter is preferably 10 μm or less, more preferably 5 μm or less.

[0036] As a method for attaching the resin particles to the outer surface of the surface layer of the belt, any of the following methods can be adopted: a method including attaching the resin particles directly (in the case of a solid) to the outer surface by using a sieve, etc.; and a method including mixing the resin particles in a dispersion medium such as water or alcohol, applying the mixture to the outer surface, and then drying the dispersion medium.

[0037] The resin particles each contain an acrylic resin and a fluororesin; a conductive agent, an antioxidant, a dispersant, or the like may be added to each particle as necessary.

[0038] <Electrophotographic image forming apparatus>

[0039] Figure 2 An example of an image forming apparatus including an electrophotographic belt as an intermediate transfer member according to one aspect of the present disclosure is shown, the image forming apparatus having the configuration of an electrophotographic image forming apparatus. The image forming apparatus is configured to form a color image by using four color toners on a recording medium S such as paper supplied from a paper supply cassette 20, and image forming stations for the respective colors are arranged in a substantially horizontal direction.

[0040] The image forming stations include photosensitive drums (photosensitive members or image bearing members) 1c, 1m, 1y and 1k, respectively. Here, suffixes "c", "m", "y" and "k" are added to the reference numerals to indicate that the image forming stations for cyan, magenta, yellow and black include the members indicated by the reference numerals, respectively. The image forming apparatus includes a laser scanner 3 as a laser optical unit, and laser beams 3c, 3m, 3y and 3k are emitted from the laser scanner 3 according to the image signals of the respective colors to irradiate the photosensitive drums 1c, 1m, 1y and 1k, respectively. The image forming station for black is described. A conductive roller 2k as a contact charging device, a developing device 4k, a conductive roller 8k as a primary transfer roller, and a toner recovery scraper 14k for cleaning the photosensitive drum 1k are arranged to surround the photosensitive drum 1k. In the developing device 4k, a developing roller 41k, a developer container 42k and a developing scraper 43k are arranged. The developing roller 41k is a developer carrying member configured to develop a latent image formed on the photosensitive drum 1k. The developer container 42k is configured to hold the toner to be supplied to the developing roller 41k. The developing scraper 43k is configured to adjust the amount of toner on the developing roller 41k and to impart an electric charge. The toner in the developer container 42k is not shown. The image forming station for yellow, cyan and magenta has the same structure as the above-mentioned image forming station for black. Therefore, the figure numerals 4m, 4y and 4c are corresponding parts of the developing device 4k, 41y, 41m and 41c are corresponding parts of the developing roller 41k, 42y, 42m and 42c are corresponding parts of the developer container 42k, 43y, 43m and 43c are corresponding parts of the developing scraper 43k, 14y, 14m and 14c are corresponding parts of the toner recovery scraper 14k, and 2m, 2y and 2c are corresponding parts of the conductive roller 2k.

[0041] The electrophotographic belt 5 having an endless belt shape is provided to be common to the image forming stations of each color. The electrophotographic belt 5 is stretched around the secondary transfer counter roller 92, the tension roller 6 and the drive roller 7, and is moved along the drive roller 7. Figure 2. In the interval between the tension roller 6 and the drive roller 7, the electronic photographic belt 5 is brought into contact with the surfaces of the photosensitive drums 1c, 1m, 1y and 1k in sequence, and is pressed toward the photosensitive drums 1c, 1m, 1y and 1k sides by the primary transfer rollers 8c, 8m, 8y and 8k, respectively. With such a configuration, the toner images formed on the surfaces of the photosensitive drums 1c, 1m, 1y and 1k are transferred to the outer peripheral surface of the electronic photographic belt 5 serving as an intermediate transfer member. The secondary transfer roller 9 is arranged to be opposite to the counter roller 92, and the electronic photographic belt 5 is pressed toward the counter roller 92 by the secondary transfer roller 9. The secondary transfer voltage is applied from the power supply to the secondary transfer roller 9 via the current detection circuit 10. The secondary transfer roller 9 and the counter roller 92 form a secondary transfer portion. The recording medium S is fed and conveyed by the feed roller 12 and the conveying roller 13, and passes through the nip portion defined between the electrophotographic belt 5 and the secondary transfer roller 9 at the position of the counter roller 92. Thus, the toner image held on the outer peripheral surface of the electrophotographic belt 5 is transferred to the recording medium S. An image is formed on the surface of the recording medium S through these actions.

[0042] The recording medium S having the toner image transferred thereto passes through the fixing device 15 including the heating roller 151 and the pressure roller 152. Thus, the image is fixed on the recording medium S, and the recording medium S is discharged to the paper discharge tray 21. At the position of the tension roller 6, a cleaning blade 11 is provided to abut against the outer peripheral surface of the electrophotographic belt 5. The toner remaining on the outer peripheral surface of the electrophotographic belt 5 and not transferred to the recording medium S is scraped off and removed by the cleaning blade 11. The cleaning blade 11 is a member extending in a direction substantially perpendicular to the moving direction of the electrophotographic belt 5.

[0043] A cleaning blade known in the field of electrophotographic image forming apparatuses can be appropriately used as the cleaning blade 11. Therefore, there is no particular limitation on the material as long as the material is suitable for toner removal, and it may be, for example, polyurethane rubber, acrylic rubber, nitrile rubber, or ethylene propylene diene rubber (EPDM). From the viewpoint of toner removal performance, polyurethane rubber is preferred.

[0044] According to one aspect of the present disclosure, an electrophotographic belt can be obtained that can suppress the occurrence of poor cleaning even when used for a long period of time. According to another aspect of the present disclosure, an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images can be obtained.

[0045] Example

[0046] Now, a belt for electrophotography according to one aspect of the present disclosure is specifically described by way of Examples and Comparative Examples, but the present disclosure is not limited thereto.

[0047] [Production at the grassroots level]

[0048] First, by using a twin-screw extruder (trade name: TEX30α, manufactured by The Japan Steel Works, LTD.), the following base material was heat-melted and kneaded at a ratio of PEN / PEEA / CB=84 / 15 / 1 (mass ratio) to thereby prepare a thermoplastic resin composition. The heat-melt kneading temperature was adjusted to fall within the range of 260° C. or more and 280° C. or less, and the heat-melt kneading time was set to about 3 minutes to about 5 minutes.

[0049] PEN: Polyethylene naphthalate (trade name: TN-8050SC, manufactured by Teijin Chemicals Ltd.)

[0050] PEEA: Polyetheresteramide (trade name: PELESTAT NC6321, manufactured by Sanyo Chemical Industries, Ltd.)

[0051] CB: Carbon black (trade name: MA-100, manufactured by Mitsubishi Chemical Corporation)

[0052] The obtained thermoplastic resin composition was granulated and dried at a temperature of 140° C. for 6 hours. Then, the dried granular thermoplastic resin composition was put into an injection molding machine (trade name: SE180D, manufactured by Sumitomo Heavy Industries, Ltd.). Then, the thermoplastic resin composition was injection molded with a mold adjusted to a temperature of 30° C. with a cylinder set temperature of 295° C. to obtain 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.

[0053] Next, by using Figure 3 The preform 104 is biaxially stretched by a biaxial stretching device (stretch blow molding machine) shown in FIG. First, before biaxial stretching, the preform 104 is arranged in a heating device 107 including a non-contact type heater (not shown) for heating the outer wall and the inner wall of the preform 104, and heated by the heater so that the outer surface temperature of the preform reaches 150° C.

[0054] Then, the heated preform 104 is arranged in a blow mold 108 whose mold temperature is maintained at 30° C., and stretched in the axial direction of the test tube shape by using a stretching rod 109. At the same time, air adjusted to a temperature of 23° C. is introduced into the preform from a blow injection portion 110 to stretch the preform 104 in the radial direction. Thus, a bottle-shaped molded product 112 is obtained.

[0055] Next, the cylindrical portion of the obtained bottle-shaped formed product 112 was cut to thereby obtain a base layer having a seamless and endless belt shape. The base layer had a thickness of 70.2 μm, a circumference of 712.2 mm, and a width of 244.0 mm.

[0056] [Formation of surface layer]

[0057] The material formulation of the surface layer forming coating material is shown in Table 1. In Table 1, parts by mass are shown, and parts by mass as solid content are shown for components other than the solvent.

[0058] For each of the surface layer formulations No. 1 and No. 3, the materials shown in Table 1 were weighed in a container, and stirred with a stirrer for 30 minutes to provide a coating.

[0059] In the surface layer formulation No. 2, the following steps were performed for dispersing polytetrafluoroethylene (PTFE). That is, the materials shown in Table 1 (except the conductive agent) were weighed in a container and subjected to a coarse dispersion process. Thereafter, the mixture was subjected to a main dispersion process using a high-pressure emulsifying disperser (trade name: NanoVater, manufactured by Yoshida Kikai Co., Ltd.).

[0060] At this time, the main dispersion treatment is performed until the 50% average particle size of the PTFE in the mixture becomes 200nm. In addition, while stirring the conductive agent (slurry), the liquid after the main dispersion treatment is added dropwise to the conductive agent to obtain a coating. The particle size of the PTFE in the coating is measured with a concentrated solution-type particle diameter analyzer (trade name: FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.) based on the dynamic light scattering (DLS) technology (standard ISO-DIS 22412).

[0061] Table 1

[0062] Surface layer formula (mass parts)

[0063]

[0064] The following describes details about the materials shown in Table 1 and the later-described Table 2. The term "MEK" means methyl ethyl ketone.

[0065] "ARONIX M-402": trade name, manufactured by Toagosei Co., Ltd.

[0066] Multifunctional acrylate (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate)

[0067] "ARONIX M-305": trade name, manufactured by Toagosei Co., Ltd.

[0068] Multifunctional acrylates, pentaerythritol triacrylate and pentaerythritol tetraacrylate

[0069] "ARONIX M-140": trade name, manufactured by Toagosei Co., Ltd.

[0070] Monofunctional acrylate, N-acryloyloxyethyl hexahydrophthalimide

[0071] "LUBRON L-2": trade name, manufactured by Daikin Industries, Ltd.

[0072] Polytetrafluoroethylene (PTFE)

[0073] "FLUOROLINK AD1700": Trade name, manufactured by Solvay Specialty Polymers Japan KK

[0074] Acrylate-based addition perfluoropolyether

[0075] "GF-300": trade name, manufactured by Toagosei Co., Ltd.

[0076] Dispersants for dispersing PTFE particles

[0077] "CELNAX CX-Z410K": trade name, manufactured by Nissan Chemical Corporation

[0078] Conductive agent, zinc antimonate particle slurry, solid content 40% by mass

[0079] "IRGACURE 907": trade name, manufactured by BASF

[0080] Photoreaction initiator

[0081] "Zinc stearate ZP": trade name, manufactured by Dainichi Chemical Industry Co., Ltd.

[0082] Zinc stearate

[0083] The base produced in the above is installed in the outer periphery of the cylindrical holding mold, and the end of the base is sealed. Thereafter, the holding mold is immersed in a container filled with paint, and it is lifted so that the relative speed between the liquid surface of the paint and the base becomes constant. Thus, a coating film of the paint is formed on the outer peripheral surface of the base. The lifting speed (the relative speed between the liquid surface of the paint and the base) and the solvent ratio of the paint can be adjusted according to the required thickness. Here, the lifting speed is set to 10mm / second to 50mm / second, and the thickness of the coating is adjusted to 3μm. The base with the coating formed thereon is placed at a temperature of 23°C and under exhaust for 1 minute to dry the coating. Thereafter, UV light is applied to the coating by using a UV irradiator (trade name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) until its cumulative light amount becomes 600mJ / cm 2 , thereby curing the coating film. Thus, an electrophotographic belt including a surface layer formed on the outer peripheral surface of the base layer was produced. The cross section of the surface layer was observed with an electron microscope (trade name: XL30-SFEG, manufactured by FEI). As a result, it was found that its thickness was 3.0 μm.

[0084] [Production and attachment of resin particles]

[0085] The material formulation of the raw material liquid for forming the resin particles is shown in Table 2. In Table 2, parts by mass are shown, and parts by mass as solid content are shown for components other than the solvent.

[0086] For each of the resin particle formulations No. 5 and No. 10, the materials shown in Table 2 were weighed in a container, and stirred with a mixing rotor or a stirrer for 30 minutes to provide a stock solution.

[0087] For each of the resin particle formulations No. 1 to 4 and 6 to 9, the following steps are performed to disperse the PTFE. That is, the materials shown in Table 2 (except the conductive agent) are weighed in a container and subjected to a coarse dispersion treatment. Thereafter, the mixture is subjected to a main dispersion treatment with a high-pressure emulsifying disperser (trade name: NanoVater, manufactured by Yoshida Kikai Co., Ltd.). At this time, the main dispersion treatment is performed until the 50% average particle size of the PTFE in the mixture becomes 200nm. Thus, a raw material solution is obtained. However, in the resin particle formulation No. 3, further, while stirring the conductive agent (slurry), the liquid after the main dispersion treatment is added dropwise to the conductive agent to provide a raw material solution. The particle size of the PTFE in each raw material solution is measured using a concentrated solution type particle size analyzer (trade name: FPAR-1000, manufactured by Otsuka Electronics Co., Ltd.) based on dynamic light scattering (DLS) technology (standard ISO-DIS22412). For each of the resin particle formulations Nos. 11 and 12, since a material available from a manufacturer of the material was used as the resin particles as it was, the above-mentioned steps such as stirring were not performed.

[0088] Table 2

[0089] Resin pellet formula (parts by mass)

[0090]

[0091] Each raw material liquid obtained in the foregoing was applied to a PTFE sheet (trade name: NAFLON, manufactured by NICHIAS Corporation) with a wire bar so as to have a thickness of 2 to 4 μm. The thickness was measured with a white light interferometer (trade name: VertScan R3300HL, manufactured by Ryoka Systems Inc.).

[0092] Thereafter, the coating film was dried at a temperature of 23° C. for 5 minutes under exhaust gas. Thereafter, UV light was applied to the coating film by using a UV irradiation machine (trade name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) until the accumulated light amount thereof became 600 mJ / cm 2 , thereby curing the coating. The obtained coating is peeled off from the PTFE sheet, and the peeled coating is crushed at 100 rpm for 5 hours with a ball mill (trade name: AV-1, manufactured by Asahi Rika Seisakusho, KK). The obtained crushed product is sieved with a 100 mesh sieve to remove coarse powder. Thus, resin particles are obtained.

[0093] The short diameter of the resin particles is 3.8 μm. The short diameter of the resin particles is measured from an image obtained with a scanning electron microscope (trade name: Sigma 500VP; manufactured by Carl Zeiss). The resin particles are observed using a scanning electron microscope at a magnification of 7,000 times, and their shortest diameter is determined from their images. The average value of the shortest diameters of 50 resin particles is taken as the short diameter of the resin particles.

[0094] The obtained resin particles are spread on the surface layer of the endless belt with a sieve, and the resin particles are attached to the surface layer by rubbing the surface layer with waste cloth. While observing the surface layer with a digital microscope (trade name: VHX-500, manufactured by Keyence Corporation), the addition and wiping of the resin particles are carried out to adjust their attachment amount. Thus, an electrophotographic belt is produced. However, the surface layer production method, the resin particle production method and the resin particle attachment method in Example 4 are described below.

[0095] <Evaluation method>

[0096] The characteristic values ​​and performance evaluation methods of the electrophotographic belts produced in the respective Examples and Comparative Examples are described below.

[0097] ·The ratio of the outer surface of the surface layer covered by the resin particles (particle coverage area ratio)

[0098] The outer surface of the surface layer of the electrophotographic belt was observed with a digital microscope (trade name: VHX-500, manufactured by Keyence Corporation), and a still image of a rectangular observation area with a size of 715 μm×535 μm was obtained. In the still image, the area of ​​the portion where the resin particles were observed (resin particle portion area), and the ratio of this area to the total area of ​​the still image (resin particle portion area / total area) was determined. The ratio was measured at 20 points on the outer surface of the surface layer, and the average value of the measured values ​​was adopted as the particle coverage area ratio. For such samples in which the particle coverage area ratio in the central portion of the belt and the particle coverage area ratio in both ends thereof are different from each other, an area from the end in the width direction of the belt toward the center in the direction up to 20 mm is adopted as the end, and an area ranging from the portion 20 mm toward the center from the end in the width direction of the belt to the central side is adopted as the central portion, and then the ratio is measured at 20 points in each area to determine the particle coverage area ratio.

[0099] Exposure of the second acrylic resin and fluororesin on the outer surface of each resin particle

[0100] Exposure of the acrylic resin and the fluororesin on the outer surface of each resin particle was confirmed by measuring information about elements on the material surface and information about chemical bonds on the material surface through microscopic attenuated total reflectance measurement (ATR) using a scanning electron microscope (SEM) and an energy dispersive X-ray spectrometer (EDS) and Fourier transform infrared spectroscopy (FT-IR analysis).

[0101] “X-MAXN80” (trade name, manufactured by Oxford Instruments) was used in energy dispersive X-ray spectrometry, and “Frontier Spotlight 400” (trade name, manufactured by PerkinElmer, Inc.) capable of micro ATR analysis was used in FT-IR.

[0102] Specifically, first, the surface of the resin particles was observed with SEM at a magnification of 7,000 times, and EDS analysis was performed to confirm that carbon atoms and fluorine atoms were detected. In addition, about one to two spatulas of resin particles were prepared, and the IR spectrum of the resin particle surface was measured with a micro ATR unit of an FT-IR analyzer. As a result, 1,213 cm-1 of each CF bond (fluorine resin) was observed. -1 Near and at 1,155cm -1 In addition, peaks at 2,925 cm-1, each derived from methylene (acrylic resin), were observed. -1 Nearby, at 2,850cm -1 Near and at 1,470cm -1 The peaks near 1,735 cm and C=O (acrylic resin) derived from the R-COO-R group -1 Nearby peaks.

[0103] Evaluation of toner removal performance (number of toner slippings after 100,000 sheets of durability)

[0104] A laser beam printer (trade name: LBP712Ci, manufactured by Canon Inc.) modified (the toner recovery of which was removed by a charging brush) was used as a Figure 2 An electrophotographic image forming apparatus of the configuration shown in . The toner removal performance was evaluated by: mounting an electrophotographic belt as an intermediate transfer belt on the electrophotographic image forming apparatus; and performing blade cleaning while printing an image. The evaluation process is described below.

[0105] In an environment of a temperature of 15° C. and a relative humidity of 10%, Japanese Industrial Standard (JIS) A4-sized paper (trade name: Extra; manufactured by OCE, basis weight: 80 g / m 2) as the recording medium S, and output an image on 100,000 sheets of paper by 2-sheet intermittent printing. At this time, an E letter image (an image of the letter "E") is output at a printing rate of 1%.

[0106] Thereafter, the number of toners that slip from the cleaning blade is counted. Specifically, in a state where the secondary transfer voltage of the device is turned off (0V), the photosensitive drum 1y is irradiated with laser light 3y, and the photosensitive drum 1m is irradiated with laser light 3m, thereby recording a red image (yellow and magenta toners) on the entire surface of an A4-sized paper. Thereafter, the cleaning blade 11 is made to clean the entire surface of the A4-sized paper once, and then the rotation of the belt is stopped. The electrophotographic belt is taken out of the electrophotographic image forming device, and its peripheral surface is observed, and then the positions where the toners remain are counted. At this time, even slightly residual toners that are not found when transferring to the recording medium (paper) are counted as toner slippage. The number of toner slippages is counted for each of the central portion and both end portions of the belt.

[0107] Evaluation of the degree of adhesion of resin particles (residual particle ratio after tape stripping operation)

[0108] The outer surface of the surface layer of the electrophotographic belt was observed with a digital microscope (trade name: VHX-500, manufactured by Keyence Corporation). Thus, a still image thereof was obtained.

[0109] In the still image, determine the area of ​​the part where the resin particles are attached (resin particle part area). Thereafter, the following adhesive tape stripping operation is repeated five times: the adhesive tape (trade name: 3M HEAT-RESISTANT POLYIMIDE TAPE, manufactured by 3MJapan Limited) is pasted to the outer surface and then peeled off; the condition is that a new adhesive surface is used each time the adhesive tape is pasted. Thereafter, the position identical to the position where the still image thereof is obtained in advance is observed again with a digital microscope, and the area of ​​the part where the resin particles are attached is determined. Calculate the residual rate of the resin particles before the adhesive tape stripping operation remaining after the adhesive tape stripping operation, that is, the ratio of the resin particle part area after the adhesive tape stripping operation to the resin particle part area before the adhesive tape stripping operation.

[0110] (Example 1)

[0111] As shown in Table 3, a surface layer is formed as described above on the peripheral surface of the aforementioned base layer by using a coating produced according to the surface layer formula No. 1. In addition, resin particles are produced according to the resin particle formula No. 1 as described above. The electronic photographic belt is produced by attaching the resin particles to the outer surface of the surface layer as described above, and evaluated. The image after durability is very satisfactory. The production conditions (e.g., the combination of the surface layer formula and the resin particle formula) of the electronic photographic belt used in each embodiment and comparative example and the evaluation results of the belt are shown in Table 3.

[0112] (Examples 2, 3, 5-1 to 5-4, 6, 7 and 8-1 to 8-4 and Comparative Examples 1 to 3)

[0113] Belts for electrophotography were each produced and evaluated in the same manner as in Example 1, except that the surface layer formulation, the resin particle formulation and the particle coverage area ratio were changed as shown in Table 3.

[0114] In each of Examples 5-3, 6, 8-3 and 8-4 among these Examples, the image after durability was satisfactory, and in each of the other Examples, the image after durability was very satisfactory. However, in Example 5-4, in the initial image before paper-through durability, the solid image had a slightly dry and crumbly feeling. The foregoing may be due to the fact that the attached amount of the resin particles is large, and thus the transferability of the toner is slightly reduced by the adhesion between the toner and the resin particles.

[0115] In Comparative Example 1, resin particles each not containing any fluorine resin were used. In Comparative Example 2, resin particles each not containing any acrylic resin were used. In Comparative Example 3, metal soap was used instead of the resin particles. In each of the Comparative Examples, many toner slip marks were observed in the image after durability.

[0116] (Example 4-1)

[0117] A coating film of the coating material produced according to the surface layer formulation No. 2 was formed on the outer peripheral surface of the aforementioned base layer by the aforementioned method. Then, UV light was applied to the coating film until its cumulative light amount became 60 mJ / cm 2 At this time, the coating film is in a "semi-cured state" that is not completely cured, and therefore the coating film is in a state that is easily deformed.

[0118] Afterwards, use Figure 4The embossing processing equipment shown in forms a groove extending in the circumferential direction of the base layer 5-1 in the outer surface of the coating film 51 in a semi-cured state formed on the outer peripheral surface of the base layer 5-1 by the following method. First, a mold obtained by forming a plurality of convex patterns extending in the circumferential direction on the outer peripheral surface of a cylinder having a diameter of 50 mm and a length of 250 mm by cutting is prepared as a cylindrical mold 81 for forming grooves. The details of the convex patterns are as follows: the height of each convexity is 3.5 μm; the length of the bottom of the convexity is 2.0 μm; the length of the top of the convexity is 0.2 μm; the interval between the convex patterns is 20 μm; and each convex pattern is continuously formed in the circumferential direction so that it surrounds the mold. The mold is produced by carbon steel (S45C) subjected to chemical nickel plating.

[0119] Next, the base layer 5-1 formed with the coating film 51 on its outer surface is installed in the outer periphery of the cylindrical holding mold 90 (circumference: 712mm). The embossing processing equipment can rotate both the cylindrical mold 81 and the holding mold 90. While maintaining the respective axial center lines of the mold 81 and the holding mold 90 are parallel to each other, the cylindrical mold 81 is pressed to the holding mold 90 with a pressing force of 60MPa, and the mold is rotated in opposite directions to each other with a revolution of 30mm / second. Thus, the convex pattern of the cylindrical mold 81 is transferred to the outer surface of the coating film in a semi-cured state. When the rotation of the holding mold 90 exceeds 1mm per week, the cylindrical mold 81 is separated from the holding mold 90.

[0120] As a result of the processing, grooves extending in the circumferential direction are formed in the outer surface of the coating film 51. In addition, resin particles each having the same composition as the surface layer formulation No. 2 (same as the resin particle formulation No. 3 in terms of composition, acrylic resin ratio: 62 mass %, fluororesin ratio: 20 mass %) are attached to the outer surface of the coating film 51.

[0121] Possible causes of the attachment of resin particles to the outer surface of the coating film 51 as a result of processing are as follows.

[0122] That is, when the cylindrical mold 81 is pressed against the coating film 51 with high pressure, the cylindrical mold 81 slightly undergoes elastic deformation in its axial direction. The elastic deformation causes a relative offset between the coating film 51 and the cylindrical mold 81 in the axial direction. In the convex pattern portion of the cylindrical mold 81, as a result of the offset, a part of the surface layer of the coating film 51 is scraped off by the cylindrical mold 81, and thereby resin particles having a short diameter of about 1 μm are generated, each of which has the same composition as the coating film 51. The resin particles are pressed against the outer surface of the coating film 51 by the cylindrical mold 81 so that the resin particles are attached to the outer surface of the coating film 51.

[0123] Next, UV light was applied to the coating film 51 by using a UV irradiation machine (trade name: UE06 / 81-3, manufactured by Eye Graphics Co., Ltd.) until the accumulated light amount thereof included the aforementioned 60 mJ / cm 2 The total is 600 mJ / cm 2 , thereby sufficiently curing the coating film 51 and the resin particles attached to the outer surface of the coating film 51. Thus, an electrophotographic belt was produced. The obtained electrophotographic belt was evaluated in the same manner as in Example 1.

[0124] (Example 4-2)

[0125] The belt is produced in the same manner as in Example 4-1 except that the cylindrical shape of the cylindrical mold 81 for forming the groove is changed to a reverse crown shape. In Example 4-1, the cylindrical shape of the mold 81 is straight, while in this embodiment, a reverse crown shape is adopted to concentrate the pressure on the ends of the annular belt. As a result, the offset is greater in the two ends of the belt than in its central portion. As a result, the amount of resin particles produced in the two ends is greater than in the central portion. The convex pattern of the cylindrical mold 81 for forming the groove is the same as that in Example 4-1. The reverse crown amount is as follows: the radius at the center along the axial direction of the cylindrical mold 81 for forming the groove and the radius at its end differ from each other by 5μm.

[0126] In each of the electrophotographic belts according to the above-mentioned Examples 4-1 and 4-2, UV light is further applied to the coating film 51 in a semi-cured state (the coating film having resin particles attached to its outer surface) during the surface layer production process to cure the coating film. It is possible that, as a result of the foregoing, the resin particles are more firmly fixed to the outer surface of the electrophotographic belt and are therefore in a state where they are hardly migrated to any other member. It is possible that, as a result of the foregoing, in each of the electrophotographic belts according to Examples 4-1 and 4-2, the resin particle residual rate after the belt peeling operation becomes very high.

[0127] Table 3

[0128] Production conditions of belts for electrophotography and evaluation results of belts.

[0129]

[0130] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An electrophotographic belt, characterized in that: It includes a surface layer comprising a first acrylic resin, wherein resin particles are present on the outer surface of the surface layer, wherein the resin particles cover the outer surface of the surface layer at a ratio of 0.1% or more and 35% or less, wherein the resin particles each contain a second acrylic resin and a fluororesin, and The second acrylic resin and the fluororesin are exposed on the outer surface of each of the resin particles. 2 . The electrophotographic belt according to claim 1 , wherein the first acrylic resin and the second acrylic resin each have a repeating unit of the same structure.

3. The electrophotographic belt according to claim 1, wherein in the outer surface of the surface layer, the resin particles are present in a larger amount in both end portions in the width direction of the electrophotographic belt than in the central portion in the width direction of the electrophotographic belt.

4. The electrophotographic belt according to claim 1, wherein an outer surface of the surface layer has a plurality of grooves provided therein extending in a circumferential direction of the electrophotographic belt. 5 . The electrophotographic belt according to claim 1 , wherein each of the first acrylic resin and the second acrylic resin is a polymerization product of a multifunctional acrylate monomer.

6. The electrophotographic belt according to claim 1, wherein the fluororesin is polytetrafluoroethylene. 7 . The electrophotographic belt according to claim 1 , wherein in the resin particles, the content of the second acrylic resin is 24% by mass or more and 90% by mass or less, and the content of the fluororesin is 5% by mass or more and 70% by mass or less. 8 . The electrophotographic belt according to claim 1 , wherein the electrophotographic belt has a thickness of 10 μm to 500 μm.

9. The electrophotographic belt according to claim 1, wherein the electrophotographic belt has an endless belt shape. 10 . The electrophotographic belt according to claim 9 , wherein the electrophotographic belt comprises a base layer having an endless belt shape and the surface layer on an outer peripheral surface of the base layer.

11. The electrophotographic belt according to claim 10, further comprising an elastic layer between the base layer and the surface layer. 12 . The electrophotographic belt according to claim 10 , wherein the surface layer has a thickness of 0.1 μm to 50 μm.

13. An electrophotographic image forming apparatus comprising: Belts for electronic photography; and a cleaning blade abutting against the outer surface of the electrophotographic belt, The electrophotographic belt is characterized in that the electrophotographic belt is the electrophotographic belt according to any one of claims 1 to 12.

Images