Electrophotographic belt, method for manufacturing electrophotographic belt, and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic belt capable of correctly detecting the contrast of a correction toner image.SOLUTION: An electrophotographic belt comprises a base layer and a surface layer on the base layer. The surface layer contains an organic silicon polymer as a binder and silica particles as roughening particles. The content of the silica particles in the surface layer is 2.5-20.0 mass%. On the surface layer side of the electrophotographic belt, when reflectance is measured with respect to incident light at 0° having a wavelength of 800-1000 nm, a minimum value of the reflectance in the wavelength of 800-1000 nm is 1.5% or more, and a difference between a maximum value and a minimum value of the reflectance in the wavelength of 800-1000 nm is 0.5% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrophotographic belt, a method for manufacturing an electrophotographic belt, and an electrophotographic image forming apparatus. [Background technology]

[0002] Electrophotographic image forming apparatuses (hereinafter also referred to as image forming apparatuses) are widely used as copying machines, printers, facsimile machines, etc. that use an electrophotographic system or an electrostatic recording system. In electrophotographic image forming devices, a tandem method is widely adopted in which a latent image formed on an image carrier (photosensitive member) is developed with toner, toner images of each color of YMCK are superimposed on an intermediate transfer belt, and then the toner images are transferred all at once onto paper to obtain a full-color image. The intermediate transfer belt used in this image forming method is required to have good toner transferability from the electrostatic latent image carrier to the intermediate transfer belt, good toner transferability from the intermediate transfer belt to the transfer material, and cleanability to completely remove residual toner after transfer.

[0003] Patent Document 1 describes an intermediate transfer belt having a base layer and a surface layer, in which less than 2.5% by mass of filler is added to a cured product obtained by curing an alkoxysilane. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-56928 Summary of the Invention [Problem to be solved by the invention]

[0005] In an image forming apparatus that produces a full-color image, the following control may be performed to achieve high color reproducibility. That is, a color misregistration correcting toner image (hereinafter simply referred to as a "correcting toner image") may be formed on an intermediate transfer belt, the correcting toner image may be detected by an optical sensor using an image density sensor, and control for correcting color misregistration may be performed based on the detection results. The optical sensor detects the correcting toner image using the difference (hereinafter simply referred to as "contrast") between the amount of light reflected from an area where the correcting toner image is not formed and the amount of light reflected from an area where the correcting toner image is formed. However, the present inventors have found that it is difficult to maintain a constant amount of reflected light from areas where no corrective toner image is formed in an intermediate transfer belt having a surface layer such as that described in Patent Document 1. If there is unevenness in the reflected light from the intermediate transfer belt, the contrast of the corrective toner image cannot be detected correctly, making it difficult to achieve high color reproducibility.

[0006] At least one aspect of the present disclosure is directed to providing an electrophotographic belt capable of correctly detecting the contrast of a corrective toner image, a method for manufacturing the electrophotographic belt, and an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images. [Means for solving the problem]

[0007] According to at least one aspect of the present disclosure, 1. An electrophotographic belt having a base layer and a surface layer on the base layer, the surface layer contains an organosilicon polymer as a binder and silica particles as roughening particles, the content of the silica particles in the surface layer is 2.5 to 20.0% by mass, When the reflectance of the surface layer side of the electrophotographic belt is measured for light having a wavelength of 800 to 1000 nm at an incident angle of 0°, the minimum value of the reflectance at a wavelength of 800 to 1000 nm is 1.5% or more, and the difference between the maximum and minimum values of the reflectance at a wavelength of 800 to 1000 nm is 0.5% or less.

[0008] Furthermore, according to at least one aspect of the present disclosure, A method for manufacturing an electrophotographic belt according to the present disclosure, comprising: The manufacturing method includes a preparation step of preparing a coating liquid for forming a surface layer; a coating step of coating the surface layer forming coating liquid on the base layer; a curing step of curing the surface layer forming coating liquid applied to the base layer, the curing step includes a step of hydrolyzing an alkoxysilane, followed by a dehydration condensation reaction to form the organosilicon polymer; the preparation step includes a step of preparing a silica particle dispersion liquid, and a step of preparing the surface layer-forming coating liquid using the silica particle dispersion liquid, The method for producing an electrophotographic belt includes a step of preparing the silica particle dispersion by mixing the silica particles, the compound containing at least one functional group selected from the group consisting of a carboxy group and a phosphate group, and at least one amine selected from the group consisting of a secondary amine and a tertiary amine.

[0009] Further, according to at least one aspect of the present disclosure, An electrophotographic image forming apparatus is provided that includes the electrophotographic belt of the present disclosure as an intermediate transfer belt. [Effects of the Invention]

[0010] At least one aspect of the present disclosure makes it possible to obtain an electrophotographic belt capable of correctly detecting the contrast of a corrective toner image. Furthermore, at least one aspect of the present disclosure makes it possible to obtain a method for manufacturing the electrophotographic belt. Furthermore, at least one aspect of the present disclosure makes it possible to obtain an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an image evaluation device according to at least one aspect of the present disclosure; [Figure 2] Illustration of interference of specularly reflected light from an electrophotographic belt with a surface layer [Figure 3] Schematic diagram of an image density sensor [Figure 4] FIG. 10 is an explanatory diagram showing the relationship between image density and the output of an image density sensor. [Figure 5] FIG. 1 is an explanatory diagram showing the spectral characteristics of the reflectance of an electrophotographic belt. [Figure 6] FIG. 10 is an explanatory diagram showing the reflectance characteristics and color variation evaluation results of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. 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.

[0013] Regarding the reason why it is difficult to keep the amount of reflected light from the portion where the corrective toner image is not formed constant in the intermediate transfer belt having a surface layer as described in Patent Document 1, The present inventors consider the following. That is, the cured product of alkoxysilane has a relatively high transmittance of the wavelength used by the optical sensor, and as shown in Figure 2, the first reflected light 201 from the surface of the intermediate transfer belt and the second reflected light 202 from the interface between the surface layer and the base layer interfere with each other and are detected by the optical sensor.

[0014] The optical path difference ΔL between the first reflected light 201 and the second reflected light 202, indicated by the dotted arrow in FIG. 2, is expressed by the following formula (1), where d is the film thickness of the surface layer and n is the refractive index. ΔL=2ndcosθ (1) When the optical path difference ΔL is an integer multiple of the wavelength λ of the incident light, the reflected light constructively interferes, and when it is a half-integer multiple, the reflected light destructively interferes. Therefore, if there is unevenness in the film thickness d of the surface layer, there will also be unevenness in the optical path difference ΔL, and there will also be unevenness in the wavelength of the light that interferes and constructively interferes. As a result, the reflected light detected by the optical sensor is likely to be uneven. In particular, when the wavelength λ used in the optical sensor is around 900 nm and the film thickness d of the surface layer is 1 to 4 μm, the values of the optical path difference ΔL and the wavelength λ will be the same or several times larger, making it easy for strong optical interference to occur. In the manufacture of the intermediate transfer belt described in Patent Document 1, a dipping method is used in which a surface layer-forming coating liquid is applied to the outer surface of a base layer. This method tends to cause unevenness in the film thickness d of the surface layer, resulting in uneven reflected output, making it difficult to maintain a constant amount of reflected light from areas where no corrective toner image is formed.

[0015] However, it has been found that the electrophotographic belt of the present disclosure has little noise when the toner amount on the electrophotographic belt used in an image forming apparatus is measured by an image density sensor, and the electrophotographic belt can accurately detect the contrast of the corrective toner image. By being able to accurately detect the contrast of the corrective toner image, color reproducibility is likely to be improved. The present inventors speculate that this is due to the following reasons. A light source that can be used in the image density sensor uses light with a wavelength of 800 to 1000 nm. In the electrophotographic belt of the present disclosure, when the reflectance of the surface layer side of the electrophotographic belt is measured for light with a wavelength of 800 to 1000 nm and an incident angle of 0°, the minimum value of the reflectance in the wavelength range of 800 to 1000 nm is 1.5% or more, and the difference between the maximum and minimum values of the reflectance in the wavelength range of 800 to 1000 nm is 0.5% or less. When the minimum reflectance is 1.5% or more, the amount of reflected light from the portion of the surface layer of the electrophotographic belt where the corrective toner image is not formed can be easily detected by an optical sensor. In other words, the amount of reflected light can be easily detected without increasing the output of the light-emitting diode or photodiode in the image density sensor described below. Increasing the output of the light-emitting diode or photodiode increases noise relatively, resulting in greater unevenness in the specular reflection light and making it difficult to accurately detect the contrast of the corrective toner image. Furthermore, when the difference between the maximum and minimum reflectance values is 0.5% or less, unevenness in the reflected light is less likely to occur even when unevenness occurs in the wavelengths of light that interfere constructively on the surface layer.

[0016] 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.

[0017] The present disclosure provides: 1. An electrophotographic belt having a base layer and a surface layer on the base layer, the surface layer contains an organosilicon polymer as a binder and silica particles as roughening particles, the content of the silica particles in the surface layer is 2.5 to 20.0% by mass, The electrophotographic belt relates to an electrophotographic belt in which, when the reflectance of the surface layer side of the electrophotographic belt is measured for light having a wavelength of 800 to 1000 nm and an incident angle of 0°, the minimum value of the reflectance at a wavelength of 800 to 1000 nm is 1.5% or more, and the difference between the maximum and minimum values of the reflectance at a wavelength of 800 to 1000 nm is 0.5% or less.

[0018] The electrophotographic belt has a base layer, and the shape of the base layer is not particularly limited, but may be, for example, a roll or belt, and is preferably an endless cylindrical type. The material that can constitute the base layer is not particularly limited, but the base layer preferably contains a resin. Examples of the resin include polyether ether ketone, polyethylene terephthalate, polybutylene naphthalate, polyester, polyimide, polyamide, polyamideimide, polyacetal, polyphenylene sulfide, polyvinylidene fluoride, and polycarbonate, as well as rubbers such as natural rubber, butadiene rubber, butyl rubber, acrylonitrile butadiene rubber, urethane rubber, silicone rubber, fluororubber, isoprene rubber, chloroprene rubber, styrene butadiene rubber, ethylene propylene rubber, ethylene propylene diene rubber, and polynorbornene rubber. Among these, polyimide is preferred. The content of the resin in the base layer is not particularly limited, but is preferably 70 to 90% by mass relative to the base layer.

[0019] The base layer preferably contains an antistatic agent. Examples of the antistatic agent include carbon black. The content of the antistatic agent in the base layer is not particularly limited, but is preferably 10 to 30% by mass relative to the base layer. The base layer can be formed by a known method using a known thermoplastic resin or thermosetting resin. Specific molding methods using a thermoplastic resin include, for example, the following methods: A resin composition is pelletized, and the pellets are molded by known molding methods such as continuous melt extrusion, injection molding, stretch blow molding, or inflation molding.

[0020] The electrophotographic belt has a surface layer on a base layer. The surface layer contains an organosilicon polymer as a binder, which tends to provide the surface layer with an appropriate hardness, thereby improving toner cleaning properties and reducing wear of the electrophotographic belt. The nanoindentation hardness of the surface on the surface layer side is preferably 100 to 1000 MPa. This range tends to make the hardness of the surface layer more suitable. As a result, the toner cleaning ability tends to improve and the amount of wear on the electrophotographic belt tends to be reduced. The nanoindentation hardness can be adjusted by changing the type and content of the organosilicon polymer.

[0021] The organosilicon polymer is not particularly limited, but for reasons of improving transferability, it is preferable that the organosilicon polymer is a polymer of alkoxysilane, and that the alkoxysilane contains a tetraalkoxysilane. Furthermore, the alkoxysilane may contain, in addition to the tetraalkoxysilane, at least one selected from the group consisting of a monoalkoxysilane, a dialkoxysilane, and a trialkoxysilane. Specifically, for example, it may contain at least one selected from the group consisting of a tetraalkoxysilane and a trialkoxysilane, and at least one selected from the group consisting of a dialkoxysilane and a monoalkoxysilane. Furthermore, the alkoxysilane may contain both a tetraalkoxysilane and a dialkoxysilane.

[0022] The alkoxysilane preferably contains tetraalkoxysilane in an amount of 80 to 100% by mass relative to the total amount of alkoxysilanes, and may contain at least one selected from the group consisting of monoalkoxysilanes, dialkoxysilanes, and trialkoxysilanes in an amount of 10 to 20% by mass relative to the total amount of alkoxysilanes.

[0023] The alkoxysilane is not particularly limited, but examples thereof include tetramethoxysilane, ethoxysilane, and the like. Examples of suitable alkoxysilanes include tetraalkoxysilanes such as trimethoxysilane, diethoxydimethoxysilane, triethoxymethoxysilane, tetraethoxysilane, and ethyl polysilicate; trialkoxysilanes such as trimethoxysilane, ethoxydimethoxysilane, diethoxymethoxysilane, and triethoxysilane; dialkoxysilanes such as dimethoxysilane, ethoxymethoxysilane, diethoxysilane, and methyl polysilicate; and monoalkoxysilanes such as methoxysilane and ethoxysilane. Among these, tetraethoxysilane and ethyl polysilicate are preferred.

[0024] There are no particular restrictions on the content of the organosilicon polymer in the surface layer, but it is preferably 70 to 98% by mass, and more preferably 80 to 95% by mass.

[0025] The surface layer may contain, as a binder, in addition to the organosilicon polymer, a cured product obtained by curing an active energy ray-curable composition such as a polyfunctional acrylate or polyurethane acrylate with ultraviolet light.

[0026] The surface layer contains silica particles as roughening particles. Roughening particles are particles that impart irregularities to the outer surface of the surface layer and have the effect of controlling toner. The inclusion of silica particles as roughening particles facilitates increasing the surface roughness of the surface layer. As a result, the first reflected light 201 in FIG. 2 becomes smaller, and the second reflected light 202 is also small due to scattering, which tends to weaken the interference between the first reflected light 201 and the second reflected light 202. As a result, reflectance unevenness is easily reduced.

[0027] Regarding the silica particles, there is no particular limitation on the shape or particle size, but it is preferable that the particle size is such that roughness can be formed on the surface of the surface layer, and that the particles are spherical. This is because spherical silica particles are more likely to achieve isotropy in terms of dispersion state and orientation state, and more likely to form surface roughness, compared to amorphous particles or fibrous materials. In addition, the silica particles are preferably surface-treated silica particles that have been subjected to a surface treatment such as hydrophobic treatment. The number average particle size of the secondary particles of the silica particles is not particularly limited, but is preferably 90 to 500 nm, more preferably 100 to 400 nm, and even more preferably 100 to 250 nm. Within the above range, the surface roughness of the surface layer tends to be suitable. As a result, the irregularity in specular reflection output tends to be reduced, and color reproducibility tends to be improved. The number average particle size of the secondary particles of the silica particles can be adjusted by using a compound containing at least one functional group selected from the group consisting of a carboxyl group and a phosphate group, and at least one amine selected from the group consisting of a secondary amine and a tertiary amine, or by changing the type or content of these compounds. A method for measuring the number average particle size of the secondary particles of the silica particles will be described later.

[0028] The content of silica particles in the surface layer is 2.5 to 20.0 mass%. Within this range, it is easy to adjust the reflectance, which will be described later. If the content of silica particles in the surface layer exceeds 20.0 mass%, the first reflected light 201 in FIG. 2 becomes too small, making it difficult to detect with an optical sensor. Furthermore, the content of silica particles in the surface layer is preferably 2.5 to 15.0 mass%, and more preferably 5.0 to 12.5 mass%. The content of silica particles can be measured by separating the silica particles from the organosilicon polymer and measuring their masses. Specifically, the measurement is carried out in the following manner.

[0029] First, the surface layer is scraped off from the electrophotographic belt. Using a 76 razor (manufactured by Nisshin EM Co., Ltd.), the entire edge of the blade is applied to the electrophotographic belt placed on a glass stand at a 45-degree angle, and the blade is moved to the tilted side to scrape off the surface layer into powder. Approximately 500 mg of this surface layer powder is collected. The powder is further crushed in an agate mortar for about 30 minutes, and the mass is measured. The above operation is repeated. Then, collect 1 g of powder from the surface layer.

[0030] 1 g of the above surface layer powder and the following materials are placed in a 20 cc glass container, and shaken for 4 hours at a vibration speed of 750 cpm using a test disperser paint shaker manufactured by Toyo Seiki Seisakusho. Glass beads (1mm) 3.0g Surface layer powder 1.0g 1-butanol 6.0g

[0031] Then, the glass beads are separated using a 100 μm mesh filter. When the separated liquid is then allowed to stand, the cured organosilicon polymer that serves as the binder in the surface layer precipitates, and the remaining liquid is separated to obtain a dispersion of silica particles. The dispersion was then left to stand for 72 hours in a 23°C environment to volatilize the solvent, 1-butanol. The mass of the resulting solids, i.e., the mass of the silica particles, was measured to determine the content of silica particles per gram of powder in the surface layer. The content (mass%) of silica particles in the surface layer was calculated from the obtained value.

[0032] When the reflectance of the surface layer side of the electrophotographic belt is measured for light of wavelength 800 to 1000 nm at an incident angle of 0°, the minimum value of the reflectance in the wavelength range of 800 to 1000 nm is 1.5% or more, and the difference between the maximum and minimum values of the reflectance in the wavelength range of 800 to 1000 nm is 0.5% or less. Because the light source of the image density sensor has a spectrum of 800 to 1000 nm, attention is focused on the reflectance of light of wavelength 800 to 1000 nm. The minimum reflectance is preferably 2.0% or more, more preferably 3.0% or more. There is no particular upper limit, but examples include 1.5 to 6.0%, 2.0% to 6.0%, and 3.0 to 5.5%. The reflectance can be adjusted by changing the number average particle size of the secondary particles of the silica particles and the content of the silica particles. Specifically, the minimum value of the reflectance can be increased by decreasing the content of the silica particles or the number average particle size of the secondary particles of the silica particles. Furthermore, the minimum value of the reflectance can be decreased by increasing the content of the silica particles or the number average particle size of the secondary particles of the silica particles. The method for measuring the reflectance will be described later.

[0033] Furthermore, if the difference between the maximum and minimum reflectance values in the wavelength range of 800 to 1000 nm is 0.5% or less, the unevenness in the wavelength of light that interferes and constructively interferes with each other in the surface layer is reduced. The difference between the maximum and minimum reflectance values is preferably 0.4% or less. There is no particular lower limit to the reflectance, but examples include 0.0 to 0.5%, 0.0 to 0.4%, and 0.1 to 0.4%. The difference between the maximum and minimum values of the reflectance can be adjusted by changing the content of silica particles or the number average particle size of secondary particles of the silica particles.

[0034] The surface layer preferably contains a compound containing at least one functional group selected from the group consisting of a carboxyl group and a phosphate group, and at least one amine selected from the group consisting of a secondary amine and a tertiary amine. Both the compound and the amine are easily adsorbed to the surface of silica particles, and therefore function as dispersants for the silica particles. By using two dispersants in this manner, it becomes easier to adjust the number-average particle size of the secondary particles of the silica particles to within the above range. Furthermore, because the compound is acidic, its use in combination with an amine can favorably adjust the pH of the coating solution for forming the surface layer. The compound containing at least one functional group selected from the group consisting of a carboxyl group and a phosphate group is not particularly limited, and examples thereof include saturated aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, and butyric acid; unsaturated aliphatic carboxylic acids such as acrylic acid and methacrylic acid; and benzoic acid. phthalic acid; phosphoric acid; and phosphonic acids such as monomethyl phosphate and monoethyl phosphate. Among these, acetic acid is preferred from the viewpoint of being more easily adsorbed to the surface of silica particles and functioning as a dispersant for silica particles. These compounds may be used alone or in combination of two or more. Whether the surface layer contains the above-mentioned compound or amine can be confirmed by measuring the mass spectrum of the molecules adsorbed on the surface of the silica particles by MALDI TOF MS.

[0035] When the content of silica particles in the surface layer is taken as 100 parts by mass, the content of the above compound is not particularly limited, but may be 0.01 to 0.50 parts by mass, preferably 0.05 to 0.50 parts by mass, and more preferably 0.10 to 0.50 parts by mass.

[0036] The secondary amine is a compound represented by the following formula (A), and the tertiary amine is a compound represented by the following formula (B). R 1 R 2 NH (A) (R 1 , R 2 are each independently any organic group) R 3 R 4 R 5 N (B) (R 3 ~R 5 are each independently any organic group)

[0037] The at least one amine selected from the group consisting of secondary amines and tertiary amines is not particularly limited, but the organic group is preferably an alkyl group. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 3 to 8. The alkyl group may be linear or branched. More specifically, aliphatic secondary amines such as dimethylamine, diethylamine, methylethylamine, dipropylamine, ethylpropylamine, methylpropylamine, and dioctylamine, and aliphatic tertiary amines such as trimethylamine, triethylamine, tripropylamine, and trioctylamine are preferred. Among these, the tertiary amine preferably includes at least one selected from the group consisting of tripropylamine and trioctylamine. Additionally, aromatic secondary amines such as diphenylamine and aromatic tertiary amines such as triphenylamine may also be used. These amines may be used alone or in combination of two or more.

[0038] When the content of silica particles in the surface layer is taken as 100 parts by mass, the content of the above amine is not particularly limited, but may be 0.01 to 1.00 parts by mass, preferably 0.10 to 1.00 parts by mass, and more preferably 0.25 to 1.00 parts by mass.

[0039] The 10-point average roughness Rzjis of the surface layer is not particularly limited, but is preferably 0.10 to 0.50 μm, and more preferably 0.10 to 0.40 μm. The surface roughness of the surface layer is favorable within this range. As a result, the first reflected light 201 in FIG. 2 is reduced, and the second reflected light 202 is also reduced due to scattering, which tends to weaken the interference between the first reflected light 201 and the second reflected light 202. As a result, reflectance unevenness is easily reduced. The 10-point average roughness Rzjis can be adjusted by changing the silica particle content and the number-average particle diameter of the secondary particles of the silica particles. Specifically, Rzjis can be increased by increasing the silica particle content or the number-average particle diameter of the secondary particles of the silica particles. Conversely, Rzjis can be decreased by decreasing the silica particle content or the number-average particle diameter of the secondary particles of the silica particles. The method for measuring the 10-point average roughness Rzjis will be described later. The thickness of the surface layer is not particularly limited, but is preferably 1.0 to 3.0 μm.

[0040] The method for manufacturing an electrophotographic belt is not particularly limited, but examples thereof include a method in which a coating liquid for each layer described below is prepared, the coating liquid is applied to a mold in the desired layer order, and the coating liquid is cured by heat drying, electron beam irradiation, or the like. That is, the method for manufacturing an electrophotographic belt preferably includes a preparatory step of preparing a surface layer-forming coating liquid, a coating step of applying the surface layer-forming coating liquid to a base layer, and a curing step of curing the surface layer-forming coating liquid applied to the base layer. It is more preferable to include a preparatory step of preparing a base layer. The preparatory step of preparing the base layer can be the above-mentioned base layer molding method. The coating method used in the coating step may be a known method such as dip coating, spray coating, flow coating, shower coating, roll coating, spin coating, ring coating, etc. Among these, ring coating is preferred.

[0041] The preparation step for preparing the coating liquid for forming a surface layer is not particularly limited, but preferably includes a step of preparing a silica particle dispersion and a step of preparing the coating liquid for forming a surface layer using the silica particle dispersion. Furthermore, the step of preparing the silica particle dispersion preferably includes a step of mixing silica particles with a compound containing at least one functional group selected from the group consisting of a carboxyl group and a phosphate group, and at least one amine selected from the group consisting of a secondary amine and a tertiary amine. Preparing the silica particle dispersion by premixing the compound and the amine, which act as a dispersant for the silica particles, with the silica particles makes the dispersion of the silica particles favorable. As a result, the number-average particle size of the secondary particles of the silica particles in the surface layer is likely to fall within the above-mentioned range. Furthermore, the mixing step preferably includes a step of dispersing using a dispersion medium such as glass beads. Dispersion methods include methods using a paint shaker, a bead mill, a sand mill, a ball mill, and a liquid collision type high-speed disperser. In the mixing step, the dispersion medium that can be used includes alcohol solvents such as methanol, ethanol, and butanol; ketone solvents; ether solvents; ester solvents; and aromatic hydrocarbon solvents.

[0042] The concentration of silica particles in the silica particle dispersion is not particularly limited, but is preferably 10 to 30% by mass, and more preferably 15 to 25% by mass. When the content of silica particles in the silica particle dispersion is taken as 100 parts by mass, the content of the above compound is not particularly limited, but may be 0.01 to 0.50 parts by mass, preferably 0.05 to 0.50% by mass, and more preferably 0.10 to 0.50 parts by mass. When the content of silica particles in the silica particle dispersion is taken as 100 parts by mass, the content of the above amine is not particularly limited, but may be 0.01 to 1.00 parts by mass, preferably 0.10 to 1.00% by mass, and more preferably 0.25 to 1.00 parts by mass.

[0043] The process for preparing the surface layer-forming coating liquid using the silica particle dispersion includes, for example, mixing an alkoxysilane with the silica particle dispersion, and the solvent may be an alcohol solvent such as methanol, ethanol, or butanol; a ketone solvent; an ether solvent; an ester solvent; or an aromatic hydrocarbon solvent. The solid content of the surface layer-forming coating liquid is not particularly limited, but is preferably 10 to 30%. Within this range, it becomes easier to achieve a surface layer thickness within the above range.

[0044] The step of curing the surface layer-forming coating liquid applied to the base layer preferably includes a step of hydrolyzing the alkoxysilane, followed by a dehydration condensation reaction to form an organosilicon polymer. By including such a curing step, it becomes easier to incorporate the organosilicon polymer into the surface layer. The conditions for the curing step are not particularly limited, but for example, the hydrolysis of the alkoxysilane and the dehydration condensation reaction can be achieved by baking for 30 minutes to 2 hours at 80 to 120° C. Here, it is preferable that the surface layer-forming coating liquid contains a compound containing at least one functional group selected from the group consisting of a carboxy group and a phosphate group, and at least one amine selected from the group consisting of a secondary amine and a tertiary amine, because this facilitates the hydrolysis of the alkoxysilane.

[0045] In this embodiment, a tandem type full-color multifunction peripheral will be described as an example of the image forming apparatus 100. However, the present disclosure is not limited to tandem-type full-color image forming apparatuses, and may also apply to other types of full-color image forming apparatuses.

[0046] <Image forming device> As shown in FIG. 1, the image forming apparatus 100 includes an apparatus main body 96 which is an image forming unit, a sheet discharge unit 97, a control unit 15, an image reading unit 98, and an operation unit 99 which serves as a UI (user interface). Image forming apparatus 100 can form a four-color full-color image on a recording medium in response to an image signal from an image reading unit 98, a host device such as a personal computer, or an external device such as a digital camera or smartphone. Note that sheet P is a recording medium on which a toner image is formed, and specific examples include plain paper, cardboard, synthetic resin sheets that are substitutes for plain paper, transparent resin sheets for overhead projectors, envelopes, postcards, coated paper, embossed paper, waterproof paper (resin sheets, resin-coated paper), etc.

[0047] The image forming apparatus 100 of this embodiment is capable of producing full-color images, and is provided with separate image forming members with similar configurations for each of the four colors: yellow image forming unit Y, magenta image forming unit M, cyan image forming unit C, and black image forming unit K. For this reason, while FIG. 1 shows the components of each of the four colors with the same reference numeral followed by a color identifier, the specification may refer to the components only by the reference numeral without the color identifier. Note that this image forming apparatus 100 is also capable of producing, for example, a black single-color (monochrome) image, a single-color image of one of the four colors, a single-color image using several of the four colors, or a multicolor image. The image forming units Y, M, C, and K for each color each include a photosensitive drum 1 that rotates while carrying a toner image, a charging roller 2, a developing device 4, and a photosensitive drum cleaning device 6. Each part of the image forming units Y, M, C, and K is unitized as a cartridge for each color, and is configured to be detachable from the device main body 96. When the life of each part has expired, the cartridges can be replaced with new ones, allowing a new toner image of each of the four colors to be formed on the intermediate transfer belt 7.

[0048] The photosensitive drum 1 is rotatable and carries an electrostatic latent image used for image formation. In this embodiment, the photosensitive drum 1 is a positively charged organic photoconductor (OPC) with an outer diameter of 30 mm, and is driven to rotate by a drive motor (not shown) in the direction of the arrow at a predetermined process speed (peripheral speed). The photosensitive drum 1 has an aluminum cylinder as a base, and has three layers coated and laminated on its surface: an undercoat layer, a photocharge generation layer, and a charge transport layer.

[0049] The charging roller 2 is a conductive rubber roller that comes into contact with the surface of the photosensitive drum 1 and rotates in response, uniformly charging the surface of the photosensitive drum 1. Depending on the voltage applied to the charging roller 2, it can be classified into an AC charging method using AC voltage + DC voltage, and a DC charging method using DC voltage only, but this embodiment uses the AC charging method, which produces less charging unevenness. The exposure device 3 emits laser light 3Y, 3M, 3C, and 3K for each color onto the uniformly charged photosensitive drums 1Y, 1M, 1C, and 1K of each color in accordance with image information of the separated colors output from the control unit 15, and electrostatic charges are formed on the photosensitive drums 1Y, 1M, 1C, and 1K of each color. A latent image is formed.

[0050] The developing device 4 contains, for example, a positively charged developer (toner) supplied from a replenishment toner bottle 14, and develops an electrostatic latent image formed on the photosensitive drum 1 by laser light from the exposure device 3. In this embodiment, a two-component development method using non-magnetic toner and magnetic carrier is adopted, and toner is supplied to a development area facing the photosensitive drum 1. A development bias (DC voltage + AC voltage) is applied to a development sleeve (not shown) of the developing device 4 that carries the toner, and the electrostatic latent image formed on the photosensitive drum 1 is developed with the toner and made visible. The toner image developed on the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 7 by the primary transfer roller 5. After the primary transfer, the photosensitive drum 1 is cleaned by a photosensitive cleaning device 6, for example, by a photosensitive cleaning blade (not shown) that is brought into contact with the photosensitive drum 1 with a predetermined pressure, to remove any residual toner that has not been transferred to the intermediate transfer belt 7. Thereafter, the surface is neutralized by a pre-exposure device (not shown), and the photosensitive drum 1 is prepared for the next image formation process.

[0051] The intermediate transfer belt 7 is wound around a drive roller 8 and a driven roller 9, includes primary transfer rollers 5Y, 5M, 5C, and 5K, and is equipped with an intermediate transfer belt cleaning device 20. These components are detachable from the device main body 96 as an intermediate transfer belt unit, and can be replaced when the component reaches the end of its life or malfunctions. The driven roller 9 is a tension roller that maintains a constant tension on the intermediate transfer belt 7. A spring (not shown) applies a force to the driven roller 9 that pushes the intermediate transfer belt 7 toward its front surface, applying a tension of approximately 20 to 50 N in the conveyance direction of the intermediate transfer belt 7. In this embodiment, the intermediate transfer belt 7 is supported by two shafts. However, it may be supported by three shafts, with one of the shafts controlling the deviation of the intermediate transfer belt 7.

[0052] The primary transfer rollers 5Y, 5M, 5C, and 5K are disposed opposite the photosensitive drums 1Y, 1M, 1C, and 1K, respectively. The primary transfer rollers 5 are disposed in pressure contact with the photosensitive drum 1, sandwiching the intermediate transfer belt 7 between them, and a primary transfer voltage of opposite polarity to the toner is applied, thereby primarily transferring the toner image formed on the photosensitive drum 1 onto the intermediate transfer belt 7. The primary transfer voltages applied to the primary transfer rollers 5Y, 5M, 5C, and 5K can be individually controlled by the control unit 15. In this embodiment, the primary transfer roller 5 has an outer diameter of, for example, 15 to 20 mm, an elastic layer made of ion-conductive foam rubber (NBR rubber), and a core metal, and has a resistance of, for example, 1×10 5 ~1×10 7 A roller of [Ω] (measurement conditions: 23°C 50% RH environment, against a Φ30 mm aluminum drum, nip width approximately 7 mm, 2 kV applied) is used.

[0053] The intermediate transfer belt 7 of this embodiment is an electrophotographic belt according to the present disclosure, which is an endless belt having a two-layer structure consisting of a base layer and a surface layer from the back side. That is, an electrophotographic image forming apparatus is equipped with the electrophotographic belt according to the present disclosure as an intermediate transfer belt. Here, the base layer is made of a material in which a polyimide resin contains an appropriate amount of carbon black as an antistatic agent. The thickness of the base layer is 50 to 150 μm. In this embodiment, the intermediate transfer belt 7 used has a base layer of polyimide resin dispersed with conductive material: 60 μm, and a surface layer of 2 μm, for a total thickness of 62 μm. The intermediate transfer belt 7 of this embodiment has a volume resistivity of 1×10 7 ~1×10 9 [Ω·cm] (measurement conditions: 23°C, 50% RH environment, resistivity measuring device, 100 V applied), nanoindentation hardness 600 MPa (measurement conditions: 23°C, 50% RH environment measurement).

[0054] The secondary transfer roller 10 is disposed in pressure contact with the drive roller 8 across the intermediate transfer belt 7. A DC voltage of a polarity opposite to the charge polarity of the toner is applied to the secondary transfer roller 10 as a secondary transfer voltage, and the four-color superimposed toner image that has been primarily transferred onto the intermediate transfer belt 7 is transferred onto the sheet P that has been supplied to the nip portion (secondary transfer portion) between the drive roller 8 and the secondary transfer roller 10. The toner images on the intermediate transfer belt 7 are secondarily transferred onto the sheet P all at once. The drive roller 8 is connected to a ground potential. In this embodiment, for example, a secondary transfer voltage of +2 to +5 kV is applied to the secondary transfer roller 10, causing a current of, for example, about 50 μA to flow, and the toner images on the intermediate transfer belt 7 are secondarily transferred onto the sheet P. In addition, the primary and secondary transfer voltages or transfer currents are arbitrary values determined according to the material of the photosensitive drum, the charge amount of the toner, the image formation speed, i.e., the rotation speed of the photosensitive drum 1 and the intermediate transfer belt 7, and, in the case of secondary transfer, the material of the sheet P.

[0055] The secondary transfer roller 10 has an outer diameter of, for example, 20 to 25 mm, and includes an elastic layer of ion-conductive foam rubber (NBR rubber) and a core metal. 5 ~1×10 7 A roller of [Ω] (measurement conditions: 23°C 50% RH environment, against a Φ30 mm aluminum drum, nip width approximately 7 mm, 2 kV applied) is used.

[0056] The intermediate transfer belt 7 also has an intermediate transfer belt cleaning device 20. The intermediate transfer belt cleaning device 20 removes toner remaining on the intermediate transfer belt 7 after the secondary transfer process. A sheet P is taken out of a cassette 12 by a paper feed roller 11 and conveyed at a predetermined timing to a secondary transfer portion of a secondary transfer roller 10, as indicated by an arrow. The sheet P carrying the secondarily transferred toner image is conveyed to a fixing device 13. The fixing device 13 as a fixing means includes a pressure roller 13b that is in pressure contact with a fixing roller 13a. As the sheet P is sandwiched and transported between the heated fixing roller 13a and the pressure roller 13b, the toner image that has been secondarily transferred onto the sheet P is heated and pressurized and fixed onto the sheet P. The sheet P on which the toner image has been fixed is conveyed to a sheet discharge section 97, and image formation on the sheet P is completed.

[0057] <Image density sensor> In this embodiment, the image density sensor 300 included in the image forming apparatus is described as being arranged to face the intermediate transfer belt 7, but the arrangement of the image density sensor is not limited to this embodiment. 3, the image density sensor 300 is disposed opposite the intermediate transfer belt 7 and measures the density of the toner image formed on the intermediate transfer belt 7. Here, a part of the structure of the image density sensor 300 will be described with reference to FIG.

[0058] FIG. 3 is a diagram for explaining the configuration of the image density sensor 300, and corresponds to a cross-sectional view when viewed from the upstream side with respect to the conveyance direction of the intermediate transfer belt 7. Image density sensor 300 is an optical sensor having a light emitting diode (LED) 301, a photodiode (PD) 302, and a photodiode (PD) 303. LED 301 is a light emitting diode arranged to irradiate the intermediate transfer belt 7 with infrared light at an incident angle of approximately 15°. PD 302 is a photodiode that receives reflected light of light irradiated from LED 301 onto the intermediate transfer belt 7 and toner image 308 at a specular reflection angle. PD 303 is a photodiode that receives scattered light at a diffuse reflection angle.

[0059] The shutter 310 is disposed between the image density sensor 300 and the intermediate transfer belt 7. When detecting the intermediate transfer belt 7 and the toner image, the shutter 310 moves to the position indicated by the solid line and is in an open state. When the image density sensor 300 is not in use, the shutter 310 moves to a position in front of the lens 304 of the image density sensor 300 as indicated by the dotted line to prevent the lens 304 from becoming dirty. The double arrow in FIG. 3 indicates the direction in which the shutter moves. A light receiving circuit having an IV conversion function that converts the current flowing according to the amount of light received by PD302 and PD303 into a voltage is mounted on electric board 307. Lens 304 provided on electric board 307 is an optical component molded from epoxy resin that creates a path for the light emitted from LED 301 and the light received by PD302 and PD303. In addition, shielding member 305 made of black resin is provided on electric board 307 to prevent the light emitted by LED 301 from directly entering PD302 and PD303. The image density sensor 300 configured as described above can measure both specularly reflected light and diffusely reflected light. The PD 302 receives specularly reflected light, and the PD 303 receives diffusely reflected light, and measure the light reflected from the intermediate transfer belt and the toner image 309.

[0060] Here, an example of a method for detecting patch density will be described. For example, a case where the patch density on the intermediate transfer belt 7 is calculated using the PD 302 that receives specularly reflected light will be described. PD302 detects both the specular reflected light component and the diffuse reflected light component, so the diffuse reflected light component detected by PD303 is removed from the reflected light component detected by PD302, and the specular reflected light component is calculated through a correction calculation. Because the reflected light from the intermediate transfer belt 7 is large and there is almost no light reflected from the toner, the specular reflected light component detected by PD302 decreases as the toner image density increases. By storing the relationship between toner image density and specular reflected light in the device in advance, the toner image density can be calculated from the detected specular reflected light and density correction is performed.

[0061] Also, a case where the patch density on the intermediate transfer belt 7 is calculated using the PD 303 that receives diffused reflection will be described. The PD303 detects only the diffusely reflected light component. Furthermore, as the toner image density increases, the amount of scattered light from the toner increases, increasing the diffusely reflected light component. By storing the relationship between the toner image density and the diffusely reflected light in the device beforehand, the toner image density can be calculated from the detected diffusely reflected light and density correction can be performed.

[0062] The light (near-infrared light) reflected from the intermediate transfer belt is input to the image density sensor 300, converted into an analog electrical signal of 0 to 5 V, and then output. This analog electrical signal is converted into an 8-bit digital signal by an A / D conversion circuit in the control unit 15. This digital signal is then converted into density information by a density conversion circuit in the control unit 15.

[0063] FIG. 4 is a diagram showing an example of the relationship between the output value of the image density sensor 300 and the density. 4, when the image density of the pattern image formed on the intermediate transfer belt 7 is changed in stages by area gradation, the output of the image density sensor 300 changes according to the density of the formed pattern image. Here, the output of the image density sensor 300 when no toner adheres to the intermediate transfer belt 7 is set to an image density level of 0, and the output changes from this level up to 255. In pixels formed on the intermediate transfer belt 7, as the area coverage rate of toner increases and the image density increases, the output of specularly reflected light decreases and the output of diffusely reflected light increases. Based on these characteristics of the image density sensor 300, a lookup table dedicated to each color is prepared in advance to convert the output of the image density sensor 300 into a density signal for each color. The lookup table is stored in the memory unit of the density conversion circuit. This allows the density conversion circuit to accurately read the pattern image density for each color. The density conversion circuit outputs the density information to the control unit 15.

[0064] <Method for evaluating the reflectance of electrophotographic belts> Using an F20 film thickness measurement system (manufactured by Filmetrics) that uses optical interferometry, the reflectance of the surface layer side of the electrophotographic belt is measured at an incident angle of 0° for wavelengths in the near-infrared region. Specifically, the measurement is carried out in the following manner: Measurements are taken at a total of 12 locations, three in the width direction. In the width direction, the measurements are taken at the center and at positions 10 mm from both ends. In the circumferential direction, measurements are taken at four locations every 90°. A bare silicon wafer is used as the standard reflector.

[0065] Fig. 5 is an explanatory diagram showing the spectral characteristics of the reflectance of an electrophotographic belt, and is an example of measuring the reflectance of an electrophotographic belt having a surface layer thickness of 2 μm at a wavelength of 600 nm to 1000 nm at an incident angle of 0°. Because the light source of the image density sensor has a spectrum from 800 to 1000 nm, the focus of the reflectance data is on the 800 to 1000 nm range. Within this wavelength range from 800 to 1000 nm, the maximum reflectance value is Rmax (%), the minimum reflectance value is Rmin (%), and the difference between the maximum and minimum reflectance values is ΔR (%) = Rmax - Rmin. ΔR (%) is determined for each of the 12 measurement points, and the arithmetic mean value is taken as the difference between the maximum and minimum reflectance values of the electrophotographic belt.

[0066] <Evaluation method for surface roughness of electrophotographic belt> The 10-point average roughness Rzjis of the electrophotographic belt is determined using a surface roughness measuring instrument (manufactured by Kosaka Laboratory, product name: SE800) that can perform measurements in accordance with JIS B0601 (2001). The measurement direction is the width direction of the intermediate transfer belt, and the cutoff value λ is 0.8 mm. Specifically, the measurement is carried out in the following procedure. That is, the electrophotographic belt is measured at a total of 12 points, 4 points in the circumferential direction and 3 points in the width direction, using the surface roughness measuring device. In the width direction, the measurement is carried out at three points: the center and positions 10 mm from both ends. In the circumferential direction, the measurement is carried out at four points every 90°. The arithmetic mean value of the obtained 10-point average roughness values is defined as the 10-point average roughness Rzjis of the electrophotographic belt.

[0067] <Number average particle size of secondary particles of silica particles> The number average particle size of the secondary particles of the silica particles in the surface layer is measured by the following procedure. (i) Take 10 measurement samples from random locations on the belt. (ii) A portion of each sample cross section is cut out with a microtome, the resulting cross section is coated with PtPd by sputtering, grounded, and observed with a scanning electron microscope (SEM) at an accelerating voltage of 5 kV and 50,000x magnification to obtain a photograph. From the photograph, the diameters of the silica particles in the belt thickness direction and in the direction perpendicular to the belt thickness direction are measured, and the arithmetic mean of these diameters is calculated as the particle diameter of the silica particles. (iii) 30 silica particles are measured for each of the 10 measurement samples, and the arithmetic mean value thereof is taken as the number average particle size of the secondary particles of the silica particles in the surface layer.

[0068] <Method for evaluating specular reflection output unevenness> The electrophotographic belt to be evaluated is mounted on a Canon imagePRESS C270. The specular reflection output per revolution of the electrophotographic belt is measured in 1 mm increments, and the arithmetic mean value Vave, maximum value Vmax, and minimum value Vmin are obtained. The specular reflection output unevenness (ΔV) is then evaluated using the following formula (2). The image density sensor is positioned ±130 mm from the center of the electrophotographic belt in the width direction. Furthermore, because the specular reflection output varies depending on the output of the LED 301, the light intensity is adjusted so that the specular reflection output is 2 V. ΔV= (Vmax-Vmin) / Vave (2)

[0069] <Evaluation method for color variation> The electrophotographic belt to be evaluated is attached to a Canon imagePRESS C270. The intermediate gradation of 127 / 255 and the maximum gradation of 255 / 255 for each YMCK monochrome are continuously output onto OK topcoat A4 127.9gsm (Oji Paper Co., Ltd.), and 50 samples are extracted every 105 sheets. The color difference ΔE76 (CIE1976) is then measured in comparison with the first sheet, and the maximum color difference for each color is found for the 50 samples, and the average is taken as ΔEmax,ave. Ta. Depending on the value of ΔEmax,ave, the color fluctuation evaluation rank was as follows: A: ΔEmax,ave value is 0.3 or less B: ΔEmax,ave is greater than 0.3 and less than 0.8 C: ΔEmax,ave value exceeds 0.8

[0070] [Example 1] <Manufacturing of electrophotographic belts> [Manufacturing of Electrophotographic Belt 1] An endless electrophotographic belt 1 having a base layer and a surface layer on the base layer, a circumference of 1048 mm, a width of 360 mm and a thickness of 60 μm was produced as follows.

[0071] (1) Preparation of an endless belt-shaped base layer To an N-methyl-2-pyrrolidone (NMP) solution of polyamic acid (3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA) called "U-Varnish-S" (18% solids, manufactured by Ube Industries, Ltd.), dried, oxidized carbon black "SPECIAL BLACK 4" (Degussa, pH 3.0, volatile content: 14.0%) was added at a ratio of 23 parts by weight per 100 parts by weight of polyimide resin solids. The mixture was collided into two 1.4 mm square sections using a collision-type disperser called "Geanus PY" (Sheenus, Inc.) at a pressure of 200 MPa, and then passed through the same path five times to separate the two sections. This resulted in a polyamic acid solution containing carbon black.

[0072] This carbon black-containing polyamic acid solution was applied to the inner surface of a cylindrical mold using a dispenser to a thickness of 0.5 mm and rotated at 1500 rpm for 15 minutes to form a uniformly thick spread layer. While rotating at 250 rpm, the mold was then exposed to hot air at 60°C from the outside for 30 minutes, followed by heating at 150°C for 60 minutes. The temperature was then increased to 360°C at a rate of 2°C / min and further heated at 360°C for 30 minutes to remove the solvent, remove the dehydrated ring-closed water, and complete the imide conversion reaction. The mixture was then returned to room temperature and peeled off from the cylindrical mold to produce a 60 μm-thick, endless belt-like base layer made of polyimide.

[0073] (2) Formation of the surface layer First, a dispersion of silica particles to be added to the surface layer-forming coating liquid was prepared by adding the following materials to a 300 cc glass container and shaking it for 4 hours at a vibration speed of 750 cpm using a Toyo Seiki Seisaku-sho test disperser paint shaker.

[0074] (Silica particle dispersion) Glass beads (1 mm) 30.0 parts by mass Silica particles (HMDS-treated, primary particle number average particle size 30 nm) 20.0 parts by mass Acetic acid 0.05 parts by mass Trioctylamine 0.10 parts by mass 1-butanol 80.0 parts by mass Thereafter, the glass beads were separated using a 100 μm mesh filter to obtain a silica particle dispersion liquid with a solid content of about 20 mass %.

[0075] Next, a coating liquid for forming a surface layer was prepared using the materials shown below. (Coating liquid for forming surface layer) Tetraethoxysilane 54.0 parts by mass Ethyl polysilicate (average pentamer) 36.0 parts by mass 20% by mass silica particle dispersion 10.0 parts by mass 1-butanol 90.0 parts by mass

[0076] A coating solution consisting only of tetraethoxysilane, ethyl polysilicate, and 1-butanol was previously baked in an air atmosphere at 100°C for 60 minutes, and the total solids content of tetraethoxysilane and ethyl polysilicate was found to be 20% by mass. Therefore, in this coating solution, 10 parts by mass of a 20% by mass silica particle dispersion contains 2 parts by mass of silica particles, relative to 18 parts by mass of an organosilicon polymer consisting of tetraethoxysilane and ethyl polysilicate. Therefore, a surface layer containing 10% by mass of silica particles can be obtained from this coating solution.

[0077] Next, the base layer obtained above was placed on the outer peripheral surface of a cylindrical mold. Then, the surface layer forming coating liquid was applied to the outer surface of the base layer by ejecting the surface layer forming coating liquid from a ring nozzle capable of applying a cylindrical coating while moving it on the outer peripheral surface (ring coating method). Thereafter, the base layer was baked in an air atmosphere at 100°C for 60 minutes to obtain an electrophotographic belt 1. The thickness of the surface layer can be adjusted by the solid content of the coating solution, but it can also be controlled by the amount of coating material discharged from the ring nozzle and the moving speed of the ring nozzle. In this example, the amount of coating material discharged was adjusted so that a surface layer with a thickness of 2.0 μm was obtained after baking at 100°C for 60 minutes in an air atmosphere.

[0078] Further, the reflectance of the electrophotographic belt 1, the surface roughness, the number average particle diameter of the secondary particles of the silica particles, the irregularity in specular reflection output, and the color variation were evaluated.

[0079] [Examples 2 and 3] Electrophotographic belts 2 and 3 were produced in the same manner as in Example 1, except that the composition of the coating liquid for forming the surface layer was changed as shown in Table 2, and were subjected to evaluation.

[0080] [Examples 4 to 6] Electrophotographic belts 4 to 6 were produced in the same manner as in Example 1, except that the dispersant added to the silica particle dispersion was changed from trioctylamine to tripropylamine and the composition of the coating liquid for forming the surface layer was changed as shown in Table 3, and were subjected to evaluation.

[0081] [Examples 7 to 9] Electrophotographic belts 7 to 9 were produced in the same manner as in Example 1, except that the amount of trioctylamine added to the silica particle dispersion was changed as shown in Table 1 and the composition of the coating liquid for forming the surface layer was changed as shown in Table 3, and were subjected to evaluation. [Table 1] In the table, the particle size indicates the number average particle size (nm) of primary particles. [Table 2] In the table, the silica particle dispersion indicates a 20 mass % silica particle dispersion.

[0082] [Comparative Examples 1 and 2] Electrophotographic belts 10 and 11 were produced in the same manner as in Example 1, except that the composition of the coating liquid for forming the surface layer was changed as shown in Table 2, and were subjected to evaluation.

[0083] [Comparative Examples 3 and 4] Electrophotographic belts 12 and 13 were produced in the same manner as in Example 4, except that the composition of the coating liquid for forming the surface layer was changed as shown in Table 2, and were subjected to evaluation.

[0084] Comparative Example 5 As shown in Table 2, an electrophotographic belt 14 was produced in the same manner as in Example 2, except that trioctylamine was not added to the silica particle dispersion liquid, and was subjected to evaluation.

[0085] Table 3 shows the results of the evaluation and image evaluation of electrophotographic belts 1 to 14. FIG. 6 is an explanatory diagram showing the reflectance characteristics and color variation evaluation results of Examples and Comparative Examples, and is a diagram summarizing the evaluation results of electrophotographic belts, particularly the reflectance characteristics and color variation evaluation results. [Table 3] In the table, the surface roughness Rzjis indicates the 10-point average roughness Rzjis of the surface layer.

[0086] As shown in Figure 6, when the minimum reflectance is 1.5% or more and the difference ΔR between the maximum and minimum reflectance is 0.5% or less, there is little color variation. This is thought to be because when the minimum reflectance is small, the output of the light-emitting diode and photodiode must be increased, and the noise from these becomes relatively large, which increases the irregularity in the specular reflection output. Furthermore, if ΔR exceeds 0.5%, and there is unevenness in the wavelengths of the interfering and constructive light, optical interference occurs on the surface of the intermediate transfer belt, resulting in greater unevenness in the specularly reflected light that enters the photodiode.As a result, accurate contrast cannot be obtained, and color variations are thought to be large.

[0087] The present disclosure includes the following configurations and methods. (Configuration 1) 1. An electrophotographic belt having a base layer and a surface layer on the base layer, the surface layer contains an organosilicon polymer as a binder and silica particles as roughening particles, the content of the silica particles in the surface layer is 2.5 to 20.0% by mass, When the reflectance of the surface layer side of the electrophotographic belt is measured for light having a wavelength of 800 to 1000 nm at an incident angle of 0°, the minimum value of the reflectance at a wavelength of 800 to 1000 nm is 1.5% or more, and the difference between the maximum and minimum values of the reflectance at a wavelength of 800 to 1000 nm is 0.5% or less. (Configuration 2) The surface layer further comprises at least one group selected from the group consisting of a carboxyl group and a phosphate group. 2. The electrophotographic belt according to claim 1, further comprising a compound containing a functional group and at least one amine selected from the group consisting of secondary amines and tertiary amines. (Configuration 3) 3. The electrophotographic belt according to claim 2, wherein the tertiary amine comprises at least one selected from the group consisting of tripropylamine and trioctylamine. (Configuration 4) 4. An electrophotographic belt according to claim 2 or 3, wherein the compound comprises acetic acid. (Configuration 5) 5. The electrophotographic belt according to any one of configurations 1 to 4, wherein the surface layer has a ten-point average roughness Rzjis of 0.10 to 0.50 μm. (Configuration 6) 6. The electrophotographic belt according to any one of configurations 1 to 5, wherein the number average particle size of secondary particles of the silica particles is 100 to 400 nm. (Method 7) A method for producing an electrophotographic belt according to any one of configurations 1 to 6, comprising the steps of: The manufacturing method includes a preparation step of preparing a coating liquid for forming a surface layer; a coating step of coating the surface layer forming coating liquid on the base layer; a curing step of curing the surface layer forming coating liquid applied to the base layer, the curing step includes a step of hydrolyzing an alkoxysilane, followed by a dehydration condensation reaction to form the organosilicon polymer; the preparation step includes a step of preparing a silica particle dispersion liquid, and a step of preparing the surface layer-forming coating liquid using the silica particle dispersion liquid, the step of preparing the silica particle dispersion includes a step of mixing the silica particles, the compound containing at least one functional group selected from the group consisting of a carboxy group and a phosphate group, and the at least one amine selected from the group consisting of a secondary amine and a tertiary amine. (Configuration 8) An electrophotographic image forming apparatus comprising the electrophotographic belt according to any one of Configurations 1 to 6 as an intermediate transfer belt. [Explanation of symbols]

[0088] 1 photosensitive drum, 2 charging roller, 3 exposure device, 4 developing device, 5 primary transfer roller, 6 photosensitive body cleaning device, 7 intermediate transfer belt, 8 driving roller, 9 driven roller, 10 secondary transfer roller, 11 paper feed roller, 12 cassette, 13 fixing device, 14 replenishment toner bottle, 15 control unit, 20 intermediate transfer belt cleaning device, 96 device main body, 97 sheet discharge unit, 98 image reading unit, 99 operation unit, 100 image forming device, P sheet (recording medium), 300 image density sensor, 301 light emitting diode, 302 photodiode, 303 photodiode, 304 lens, 305 shielding member, 307 electric board, 308 toner image, 310 shutter

Claims

1. 1. An electrophotographic belt having a base layer and a surface layer on the base layer, the surface layer contains an organosilicon polymer as a binder and silica particles as roughening particles, the content of the silica particles in the surface layer is 2.5 to 20.0 mass %, When the reflectance of the surface layer side of the electrophotographic belt is measured for light having a wavelength of 800 to 1000 nm at an incident angle of 0°, the minimum value of the reflectance in the wavelength range of 800 to 1000 nm is 1.5% or more, and the difference between the maximum and minimum values of the reflectance in the wavelength range of 800 to 1000 nm is 0.5% or less.

2. 2. The electrophotographic belt according to claim 1, wherein the surface layer further comprises a compound containing at least one functional group selected from the group consisting of a carboxyl group and a phosphate group, and at least one amine selected from the group consisting of a secondary amine and a tertiary amine.

3. 3. The electrophotographic belt of claim 2, wherein said tertiary amine comprises at least one selected from the group consisting of tripropylamine and trioctylamine.

4. 3. An electrophotographic belt as in claim 2 wherein said compound comprises acetic acid.

5. 2. The electrophotographic belt according to claim 1, wherein the surface layer has a ten-point average roughness Rzjis of 0.10 to 0.50 μm.

6. 2. The electrophotographic belt according to claim 1, wherein the number average particle size of secondary particles of said silica particles is 100 to 400 nm.

7. A method for manufacturing an electrophotographic belt according to any one of claims 1 to 6, comprising the steps of: The manufacturing method includes a preparation step of preparing a coating liquid for forming a surface layer; a coating step of coating the surface layer forming coating liquid on the base layer; a curing step of curing the surface layer forming coating liquid applied to the base layer, the curing step includes a step of hydrolyzing an alkoxysilane, followed by a dehydration condensation reaction to form the organosilicon polymer; the preparation step includes a step of preparing a silica particle dispersion liquid, and a step of preparing the surface layer-forming coating liquid using the silica particle dispersion liquid, the step of preparing the silica particle dispersion includes a step of mixing the silica particles, the compound containing at least one functional group selected from the group consisting of a carboxy group and a phosphate group, and the at least one amine selected from the group consisting of a secondary amine and a tertiary amine.

8. 7. An electrophotographic image forming apparatus comprising the electrophotographic belt according to claim 1 as an intermediate transfer belt.

Images