JP6132195B2 - Intermediate transfer body and image forming apparatus using the same - Google Patents

Description

  The present invention relates to an intermediate transfer member that temporarily holds a toner image, and an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer using the intermediate transfer member.

  An image forming apparatus that uses an intermediate transfer belt as an intermediate transfer member is useful as a multicolor image forming apparatus such as a color image forming apparatus that outputs a color print by sequentially laminating and transferring a plurality of color component images. An intermediate transfer belt used in this type of image forming apparatus is required to suppress deformation such as elongation of the belt itself due to continuous use and to improve positional accuracy. Further, the intermediate transfer belt is laid out over a wide area of the apparatus, and a high voltage is applied for the transfer, so that it is required to have excellent flame retardancy. In order to meet such a demand, for example, a resin such as a polyimide resin or a polyamide-imide resin having a high elastic modulus (dimensional stability) and a high heat resistance is used as a material for the intermediate transfer belt.

  However, an intermediate transfer belt using a resin having a high elastic modulus has a high surface hardness. For this reason, for example, in a primary transfer unit that transfers a toner image from a photoconductor as an image carrier to an intermediate transfer belt and a secondary transfer unit that transfers a toner image from an intermediate transfer belt to a recording medium, a high pressure is applied to the toner image. It will take. For this reason, a so-called hollow image in which toner aggregates locally and a part of the image is not transferred may occur.

  In addition, the intermediate transfer belt using a resin with a high elastic modulus has poor followability to the contact member such as a recording medium in the primary transfer portion and the secondary transfer portion, and therefore, a partial contact failure portion (gap) is generated. This may cause uneven transfer. In recent years, in color image forming apparatuses, various papers are often used as recording media, and not only ordinary smooth papers but also recycled papers such as coated papers with high slip smoothness such as coated papers. Rough surfaces such as embossed paper, Japanese paper and kraft paper are used. Such followability to papers having different surface properties is important. If the followability of the intermediate transfer belt is poor, uneven unevenness in color and uneven color tone occur on the paper.

  As a method for improving the transfer failure and transfer unevenness described above, a configuration in which a relatively flexible elastic layer is laminated on a base layer in order to make the surface of the intermediate transfer belt elastic is proposed. Since the surface of the intermediate transfer belt is made elastic, the surface of the intermediate transfer belt is freely deformed according to the thickness of the toner image, so that the stress concentration on the toner image is reduced and the above-described transfer failure is improved. Further, since the surface of the intermediate transfer belt is made elastic, the followability to the contact member is also improved, so that the followability to sheets having different surface properties is also improved, and the above-described transfer unevenness is improved.

  However, when a relatively flexible elastic layer is used as the surface layer, the releasability of the surface layer is poor. For this reason, in the secondary transfer portion, the toner transferred to the surface layer of the intermediate transfer belt cannot be released successfully, transfer efficiency is lowered, and the above-described effects cannot be utilized. When the elastic layer is a surface layer, there is a problem that it is inferior in durability such as wear resistance and scratch resistance.

  On the other hand, a proposal has been made to newly provide a protective layer on the elastic layer of the intermediate transfer belt. However, when a protective layer made of a material having a sufficiently high transfer performance is provided, the protective layer cannot follow the flexibility of the elastic layer, which causes a problem that cracking or peeling occurs.

  In addition, proposals have been made to attach or contain fine particles on the elastic layer of the intermediate transfer belt. For example, Patent Document 1 proposes a configuration in which the surface of the intermediate transfer belt is covered with fine particles (beads) having a diameter of 3 μm or less that are smaller than toner particles. In Patent Document 2 and Patent Document 3, a particle layer is formed on the surface of the intermediate transfer belt, which is composed of a hydrophobized fine particle having a very small particle diameter compared to toner particles and a material having an affinity for the hydrophobized fine particle. A configuration has been proposed. Patent Documents 4 and 5 propose a configuration in which relatively large fine particles, which are smaller than toner particles, are embedded to some extent in the elastic layer (surface layer) of the intermediate transfer belt. Patent Documents 6 and 7 propose a configuration in which silicone resin particles or fluororesin particles are included in the elastic layer (surface layer) of the intermediate transfer belt.

  However, the above-described conventional intermediate transfer belt does not sufficiently satisfy characteristics such as transferability and durability required for recent image forming apparatuses. For example, in the intermediate transfer belt described in Patent Document 1, fine particles are liable to be detached from the belt surface during long-term use, and the durability cannot be sufficiently satisfied. Since the surface of the fine particles is smooth, it is considered that the adhesion to the elastic layer is weak.

  In the intermediate transfer belt described in Patent Documents 1 to 5, fine particles having a strong cohesive force such as silica particles are preferably used. Therefore, it is difficult to form a particle layer by uniformly dispersing the fine particles, and there is a possibility that the fine particle distribution may be non-uniform, for example, the degree of embedding of the fine particles varies greatly depending on the location. Therefore, it is considered that the transfer performance varies depending on the location, and the transfer performance varies.

  Also in the intermediate transfer belts described in Patent Document 6 and Patent Document 7, it is difficult to uniformly disperse the silicone resin particles and the fluororesin particles to form a particle layer, and there is a possibility that the distribution of fine particles may be uneven. It was. Therefore, it is considered that the transfer performance varies depending on the location, and the transfer performance varies. Further, if a particle layer made of silicone resin particles or fluororesin particles is directly laminated on the elastic layer, the particle layer cannot follow the flexibility of the elastic layer, and there is a possibility that cracking or peeling occurs.

  The present invention has been made in view of the above problems. The object is to prevent the separation of fine particles and to maintain high transfer performance not only in the initial stage but also in the long term, and an image forming apparatus capable of obtaining a high-quality image over the long term. Is to provide.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to an intermediate transfer member in which at least a base layer and an elastic layer are laminated, and the surface of the elastic layer has an irregular shape with silicone fine particles, and the silicone fine particles are spherical. It has a plurality of protrusions uniformly on the surface of the base particle.

  As described above, according to the present invention, fine particles are not easily detached, and high transfer performance can be maintained over a long period of time as well as an initial period, and an excellent quality image can be obtained over a long period of time. effective.

FIG. 3 is a schematic diagram illustrating a configuration of an intermediate transfer belt according to the present embodiment. The schematic diagram which shows the shape of a spherical-shaped particle typically. The schematic diagram which shows the shape of a spherical-shaped particle typically. The schematic diagram which shows the shape of a spherical-shaped particle typically. The figure which shows the image which image | photographed the surface of the microparticles | fine-particles which concern on this embodiment. The enlarged schematic diagram explaining a mode that the surface of the intermediate transfer belt was observed from right above. FIG. 6 is a schematic diagram illustrating a method for producing a surface state of an intermediate transfer belt. 1 is a configuration diagram showing a configuration of an image forming apparatus according to an embodiment. FIG. 6 is a configuration diagram showing a configuration of an image forming apparatus according to another embodiment.

  Hereinafter, an embodiment of an intermediate transfer belt as an intermediate transfer member to which the present invention is applied will be described. FIG. 1 is a schematic diagram illustrating a configuration of an intermediate transfer belt according to the present embodiment. As shown in FIG. 1, the intermediate transfer belt 10 according to this embodiment includes a base layer 11 and an elastic layer 12, and the surface of the elastic layer 12 is uniformly uneven with silicone fine particles 13. As will be described later, the silicone fine particles 13 are arrayed (embedded) independently on the elastic layer 12 in the plane direction, and there is almost no overlapping of the particles in the layer thickness direction or complete embedding in the elastic layer 12. It is a single particle layer.

[Base layer]
First, the base layer 11 will be described. The base layer 11 contains an electrical resistance adjusting agent so as to have predetermined electrical characteristics in a relatively flexible resin. For example, the base layer 11 preferably has a tensile elastic modulus of 3000 MPa or more from the viewpoint of dimensional stability.

  There is no restriction | limiting in particular as thickness of the said base layer 11, Although it can select suitably according to the objective, 30 micrometers-150 micrometers are preferable, 40 micrometers-120 micrometers are more preferable, 50 micrometers-80 micrometers are especially preferable. If the thickness of the base layer 11 is less than 30 μm, the belt may be easily torn by cracking, and if it exceeds 150 μm, the belt may be broken by bending. On the other hand, when the thickness of the base layer 11 is within the particularly preferable range, it is advantageous in terms of durability. The method for measuring the thickness of the base layer 11 is not particularly limited and may be appropriately selected according to the purpose. For example, the measurement with a contact type or eddy current type thickness meter or the cross section of the base layer 11 is scanned. The method of measuring with a scanning electron microscope (SEM) is mentioned.

The electrical characteristics of the base layer 11, the surface resistivity ^{1 × 10 8 Ω / □ ~1} × 10 13 Ω / □, be a ^{1 × 10 8 Ω · cm~1 ×} 10 11 Ω · cm in volume resistivity preferable. The resistance value is adjusted by including an electric resistance adjusting material in the resin, but an electric resistance adjusting material that can achieve a resistance value in the above range with an addition amount that does not cause the base layer 11 to be brittle and easily broken from the viewpoint of mechanical strength is selected. To do. In other words, the intermediate transfer belt 10 is a seamless belt that balances electrical characteristics (surface resistance and volume resistance) and mechanical strength by using a coating liquid in which the composition of the resin component and the electrical resistance adjusting material is appropriately adjusted. Preferably manufactured and used.

  As the resin used for the base layer 11, for example, a fluorine-based resin such as polyvinylidene fluoride (PVDF) or ethylene / tetrafluoroethylene copolymer (ETFE), a polyimide resin, or a polyamideimide resin is preferably used. In particular, a polyimide resin or a polyamide-imide resin is preferably used from the viewpoint of high elastic modulus (mechanical strength) and high heat resistance (flame retardant). The polyimide resin and polyamideimide resin used in this embodiment are from manufacturers such as Toray DuPont, Ube Industries, Shin Nippon Rika, JSR, Unitika, IST, Hitachi Chemical, Toyobo, and Arakawa Chemical. Commercial products can be used.

  Examples of the electric resistance adjusting material used for the base layer 11 include metal oxide, carbon black, an ionic conductive agent, and a conductive polymer material. Examples of the metal oxide include zinc oxide, tin oxide, titanium oxide, zirconium oxide, aluminum oxide, and silicon oxide. Moreover, in order to improve dispersibility, the metal oxide may be subjected to surface treatment in advance. Examples of carbon black include ketjen black, furnace black, acetylene black, thermal black, and gas black. Examples of the ionic conductive agent include tetraalkylammonium salts, trialkylbenzylammonium salts, alkylsulfonates, alkylbenzenesulfonates, alkyl sulfates, glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acids. Alcohol ester, alkyl betaine, lithium perchlorate, etc. are mentioned, and these may be used in combination. Note that the electrical resistance adjusting material used in the intermediate transfer belt 10 according to the present embodiment is not limited to the above exemplary compounds.

  In the case of carbon black, the content of the electric resistance adjusting material in the base layer 11 is 10 wt% to 25 wt%, preferably 15 wt% to 20 wt% of the total solid content in the coating liquid. Moreover, as content in the case of a metal oxide, it is 1 wt%-50 wt% of the total solid of a coating liquid, Preferably it is 10 wt%-30 wt%. If the content is less than the range of each of the electric resistance adjusting materials described above, it becomes difficult to obtain the uniformity of the resistance value, and the fluctuation of the resistance value with respect to an arbitrary potential increases. On the other hand, if the content is larger than the above ranges, the mechanical strength of the intermediate transfer belt 10 is lowered, which is not preferable in actual use.

  In addition, the base layer 11 further contains additives such as a dispersion aid, a reinforcing material, a lubricant, a heat conduction material, and an antioxidant, as necessary, in the coating liquid containing at least the resin component. Also good.

[Elastic layer]
Next, the elastic layer 12 will be described. The elastic layer 12 is preferably made of a flexible elastomer material or rubber material. As for the flexibility of the elastic layer 12, the micro rubber hardness value at 25 ° C. and 50% RH is preferably 40 or less. The micro rubber hardness can be measured by using a commercially available micro rubber hardness meter, for example, by using “Micro Rubber Hardness Meter MD-1” manufactured by Kobunshi Keiki Co., Ltd.

  The elastic layer 12 has a thickness of preferably 400 μm to 1000 μm, more preferably 500 μm to 700 μm. If the layer thickness of the elastic layer 12 is less than 400 μm, the image quality for a paper type having surface irregularities will be insufficient. On the other hand, when the thickness of the elastic layer 12 exceeds 1000 μm, the weight of the layer becomes heavy, and it becomes easy to bend, the warpage becomes large and the running performance becomes unstable, or the roller curvature for stretching the belt. It is not preferable because a crack is easily generated by bending at the portion. In addition, as a measuring method of the layer thickness of the elastic layer 12, a cross section can be measured with a scanning microscope (SEM).

  The elastomer material used for the elastic layer 12 is a thermoplastic elastomer such as polyester, polyamide, polyether, polyurethane, polyolefin, polystyrene, polyacryl, polydiene, silicone-modified polycarbonate, and fluorine. Examples include polymer systems. Further, examples of thermosetting include polyurethane, silicone-modified epoxy, and silicone-modified acrylic.

  The rubber material used for the elastic layer 12 includes isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicone rubber, chloroprene rubber, acrylic rubber, chlorosulfonated polyethylene, fluorine rubber, urethane rubber. And hydrin rubber.

  As the elastic layer 12, a material capable of obtaining performance is appropriately selected from various elastomers and rubbers. In this embodiment, ozone resistance, flexibility, adhesion to spherical fine particles, and imparting flame retardancy are provided. From the viewpoint of environmental stability, acrylic rubber is most preferable. Hereinafter, the acrylic rubber will be described.

  The acrylic rubber used for the elastic layer 12 may be currently marketed and is not particularly limited. However, among the various crosslinking systems (epoxy groups, active chlorine groups, carboxyl groups) of acrylic rubber, the carboxyl group crosslinking system is excellent in rubber properties (especially compression set) and processability, so select the carboxyl group crosslinking system. It is preferable to do.

  The crosslinking agent used for the carboxyl group-crosslinked acrylic rubber is preferably an amine compound, and most preferably a polyvalent amine compound. Specific examples of such amine compounds include aliphatic polyvalent amine crosslinking agents and aromatic polyvalent amine crosslinking agents. Examples of the aliphatic polyvalent amine cross-linking agent include hexamethylene diamine, hexamethylene diamine carbamate, N, N′-dicinnamylidene-1,6-hexane diamine, and the like. Aromatic polyvalent amine crosslinking agents include 4,4′-methylenedianiline, m-phenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4 ′-(m-phenylenediene. Isopropylidene) dianiline, 4,4 ′-(p-phenylenediisopropylidene) dianiline, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 4,4′-diaminobenzanilide, 4, 4'-bis (4-aminophenoxy) biphenyl, m-xylylenediamine, p-xylylenediamine, 1,3,5-benzenetriamine, 1,3,5-benzenetriaminomethyl and the like can be mentioned.

  The blending amount of the crosslinking agent is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the acrylic rubber. When the blending amount of the crosslinking agent is too small, crosslinking is not sufficiently performed, so that it is difficult to maintain the shape of the crosslinked product. On the other hand, when there is too much content of a crosslinking agent, a crosslinked material will become hard too much and the elasticity as crosslinked rubber, etc. will be impaired.

  In the elastic layer 12 made of acrylic rubber, a crosslinking accelerator may be further blended and used in combination with the crosslinking agent. The crosslinking accelerator is not limited, but is preferably a crosslinking accelerator that can be used in combination with the polyvalent amine crosslinking agent. Examples of such a crosslinking accelerator include guanidine compounds, imidazole compounds, quaternary onium salts, tertiary phosphine compounds, weak metal alkali metal salts, and the like. Examples of the guanidine compound include 1,3-diphenylguanidine, 1,3-diortolylguanidine and the like. Examples of the imidazole compound include 2-methylimidazole and 2-phenylimidazole. Examples of the quaternary onium salt include tetra n-butylammonium bromide and octadecyltri-n-butylammonium bromide. Examples of the polyvalent tertiary amine compound include triethylenediamine and 1,8-diaza-bicyclo [5.4.0] undecene-7 (DBU). Examples of the tertiary phosphine compound include triphenylphosphine and tri-p-tolylphosphine. Examples of the weak metal alkali metal salts include inorganic weak acid salts such as sodium or potassium phosphates and carbonates, and organic weak acid salts such as stearates and laurates.

  The amount of the crosslinking accelerator used is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 10 parts by weight per 100 parts by weight of the acrylic rubber. When there are too many crosslinking accelerators, the crosslinking rate may become too fast at the time of crosslinking, the bloom of the crosslinking accelerator on the surface of the crosslinked product may occur, or the crosslinked product may become too hard. If the amount of the crosslinking accelerator is too small, the tensile strength of the crosslinked product may be significantly reduced, or the elongation change after heat load or the tensile strength change may be too large.

  In preparing the acrylic rubber, an appropriate mixing method such as roll mixing, Banbury mixing, screw mixing, or solution mixing can be employed. The order of blending is not particularly limited, but after sufficiently mixing components that are not easily reacted or decomposed by heat, as a component that is easily reacted by heat or a component that is easily decomposed, for example, a crosslinking agent or the like at a temperature at which reaction or decomposition does not occur. What is necessary is just to mix in a short time.

  Acrylic rubber can be made into a crosslinked product by heating. The heating temperature is preferably 130 ° C to 220 ° C, more preferably 140 ° C to 200 ° C, and the crosslinking time is preferably 30 seconds to 5 hours. As a heating method, a method used for crosslinking of rubber such as press heating, steam heating, oven heating, hot air heating and the like may be appropriately selected. Further, after cross-linking once, post-cross-linking may be performed in order to surely cross-link to the inside of the cross-linked product. Post-crosslinking varies depending on the heating method, crosslinking temperature, shape, etc., but is preferably performed for 1 hour to 48 hours. What is necessary is just to select the heating method and heating temperature at the time of post-crosslinking suitably.

  The elastic layer 12 is composed of the above-described materials, a resistance adjusting agent for adjusting electrical characteristics, a flame retardant for obtaining flame retardancy, and an antioxidant, a reinforcing agent, a filler, and vulcanization acceleration as necessary. A material such as an agent is appropriately contained.

The resistivity control necessary for the intermediate transfer belt 10 requires addition of a conductive agent because the acrylic rubber alone has a high resistivity. For controlling the resistivity, carbon or an ionic conductive agent can be added. However, in the intermediate transfer belt 10 according to the present embodiment, the rubber hardness is important, so that the addition of a small amount is effective, and the rubber hardness is affected. The use of no ionic conducting agent is preferred. Specifically, it is preferable to add 0.01 to 3 parts of various perchlorates and ionic liquids with respect to 100 parts of rubber. If the addition amount of the ionic conductive agent is less than 0.01 part, the effect of reducing the resistivity cannot be obtained, and if the addition amount exceeds 3 parts, the possibility that the conductive agent blooms or bleeds to the belt surface becomes high. The resistance value of the elastic layer 12 is 1 × 10 ⁸ Ω / □ to 1 × 10 ¹³ Ω / □ in surface resistance and 1 × 10 ⁷ Ω · cm to 1 × 10 ¹² Ω · cm in volume resistance. It is preferable to adjust.

[Fine particles]
Next, the silicone fine particles 13 adhered on the elastic layer 12 will be described. Here, the silicone fine particles 13 are fine particles having an average particle diameter of 20 μm or less and having a plurality of protrusions uniformly on the surface of the true spherical base particles. The silicone fine particles 13 are insoluble in an organic solvent and have a 3% thermal decomposition temperature of 100 ° C. or higher.

  Here, the shape of the spherical particles is defined as follows. 2 to 4 are schematic views schematically showing the shape of spherical particles. 3 and 4, when a spherical particle is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the ratio of the major axis to the minor axis (r2 Particles having a / r1) ratio of 0.9 to 1.0 and a ratio of thickness to minor axis (r3 / r2) of 0.9 to 1.0 are defined as true spherical particles. When the ratio of the major axis to the minor axis and the ratio of the thickness to the minor axis (r3 / r2) is less than 0.9, it is difficult to align and align the surface of the elastic layer. drop down. The major axis r1, the minor axis r2, and the thickness r3 can be measured by, for example, the following method. That is, particles are uniformly dispersed and adhered on a smooth measurement surface, and 100 particles are enlarged to an arbitrary magnification (for example, 1000 times) by a color laser microscope “VK-8500” (manufactured by Keyence Corporation), respectively, r1, r2 and r3 are measured and obtained from their arithmetic average values.

  Next, the surface shape of the silicone fine particles 13 will be described. FIG. 5 is a view showing an image obtained by photographing the surface of the fine particles according to the present embodiment. As shown in FIG. 5, the silicone fine particles 13 according to the present embodiment are characterized by their surface shape, and have a so-called confetti shape having a plurality of protrusions uniformly on the surface of the true spherical base particles. More preferably, the protrusion extends over the entire surface of the base particle.

  The silicone fine particles 13 have a plurality of protrusions on the entire surface of the true spherical base particles and have a so-called confetti shape. Therefore, the silicone fine particles 13 have high adhesion (anchor effect) to the elastic layer 12 and maintain transfer performance over a long period of time. it can. Further, as can be seen from the results of Examples described later, the silicone fine particles 13 are not uniformly arranged in an agglomerated state but are formed as a single particle layer on the elastic layer 12 and uniformly aligned. For this reason, there is little variation in transfer performance such as different transfer performance depending on the location, and high transfer performance can be exhibited.

  The silicone fine particles 13 preferably have an average particle size of 10 μm or less, more preferably 2.0 to 6.0 μm. If the average particle diameter exceeds 10 μm, the residual charging potential due to the particles causes a problem that image disturbance occurs due to accumulation of the potential during continuous image output. The average particle diameter here means the size of the entire fine particles including the protrusions. Although the measuring method of an average particle diameter is not specifically limited, For example, it can measure with Nikkiso Co., Ltd. MICROTRAC UPA.

  Further, as the surface shape of the silicone fine particles 13, (average height of protrusions) / (average particle diameter of base particles) is preferably 0.01 to 0.3. In the silicone fine particles 13, if (average height of protrusions) / (average particle diameter of base particles) is less than 0.01, the particles are easily detached. On the other hand, if (average height of protrusions) / (average particle diameter of base particles) exceeds 0.3, the steric hindrance between the particles increases, making it difficult to form and align the silicone fine particles 13 in a single layer. The surface area occupied ratio cannot be increased to 60% or more, and transferability is deteriorated.

  Such silicone fine particles 13 can be produced by a known method. For example, there are methods described in Japanese Patent Nos. 3455562 and 4271725. As the material, polymethylsilsesquioxane or methyl methacrylate crosspolymer, which is excellent in transferability (releasability), is preferable. For example, as a commercial product, both the base particles and the protrusions are polymethylsilsesquioxane, trade name: TOSPEARL 150KA (manufactured by Momentive Performance Materials) and the like can be used. Moreover, the brand name; Silcrusta MK03 (made by Nikko Rika Co., Ltd.) etc. whose base particle is a methyl methacrylate crosspolymer and the protrusions on the surface are polymethylsilsesquioxane can be used. The measurement method of (average height of protrusions) / (average particle diameter of base particles) is not particularly limited, but can be determined by observing with, for example, a laser microscope or a scanning electron microscope (SEM).

[Intermediate transfer belt surface condition]
Next, the surface state of the intermediate transfer belt 10 in this embodiment will be described. FIG. 6 is an enlarged schematic diagram for explaining a state in which the surface of the intermediate transfer belt is observed from directly above. As shown in FIG. 6, the surface of the intermediate transfer belt 10 has a form in which the silicone fine particles 13 are independently and uniformly aligned on the elastic layer 12, and the overlapping of the silicone fine particles 13 is hardly observed, and single particles A layer is formed. The occupied area ratio of the surface of the intermediate transfer belt 10 by the silicone fine particles 13 is preferably 60% or more. If it is less than 60%, the exposed portion of the elastic layer 12 (rubber or elastomer) is too much, and the toner comes into contact with the elastic layer (rubber or elastomer), the releasability is lowered and good transferability cannot be obtained.

  Further, in the intermediate transfer belt 10 according to the present embodiment, the silicone fine particles 13 are partially embedded in the elastic layer (rubber or elastomer) 12, but the embedding rate exceeds 50%, 100 Less than% is preferable, and 51% to 90% is more preferable. When the burying rate of the silicone fine particles 13 is 50% or less, the particles are likely to be detached during long-term use in the image forming apparatus, resulting in poor durability. On the other hand, when the burying rate of the silicone fine particles 13 is 100%, the effect of the particles on the transferability is reduced, which is not preferable. The burying rate is a rate of burying in the elastic layer 12 (rubber or elastomer) having a diameter in the depth direction of the particles. Here, the burying rate means that all particles exceed 50% and 100%. It does not mean that it is less than%. The numerical value expressed by the average burial rate when viewed from a certain field of view should not exceed 50% and less than 100%. However, when the burying rate is 50%, almost no particles completely embedded in the elastic layer 12 are observed in the cross-sectional observation by the electron microscope (the number of the silicone fine particles 13 completely embedded in the elastic layer 12). % Is 5% or less of the whole particles).

[Method for producing intermediate transfer belt]
Next, an example of a method for producing the intermediate transfer belt 10 according to the present embodiment will be described. First, the base layer 11 is made to uniformly apply a coating liquid containing at least a resin component to the entire outer surface of the cylindrical shape with a liquid supply device such as a nozzle or a dispenser while slowly rotating a cylindrical shape such as a cylindrical metal mold. Apply and cast (form a coating film). In this embodiment, the coating liquid containing a polyimide resin precursor or a polyamideimide resin precursor is used for the coating liquid containing at least a resin component. Thereafter, the rotational speed of the cylindrical mold is increased to a predetermined speed, and the solvent in the coating film is evaporated at a temperature of about 80 to 150 ° C. while gradually raising the temperature while rotating the cylindrical mold. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (such as volatilized solvent). When the self-supporting film is formed, the whole cylinder is transferred to a heating furnace (firing furnace) capable of high-temperature treatment, and the temperature is raised stepwise. Finally, high-temperature heat treatment (baking) at about 250 ° C. to 450 ° C. is performed, and the polyimide resin precursor or polyamideimide resin precursor is sufficiently imidized or polyamideimidized. And after fully cooling, the elastic layer 12 is laminated | stacked continuously.

  The elastic layer 12 can be manufactured by coating and forming on the base layer 11 using a rubber paint in which rubber is dissolved in an organic solvent, and then drying and vulcanizing the solvent. As the coating molding method, similar to the base layer 11, existing coating methods such as spiral coating, die coating, and roll coating can be applied. For example, as with the base layer 11, while slowly rotating the cylindrical mold, a rubber coating is applied and cast (with a coating film on the entire outer surface of the cylindrical mold with a liquid supply device such as a nozzle or dispenser). Form. Subsequently, leveling is performed by maintaining a predetermined rotation speed and drying temperature of the cylindrical shape. During rotation, heating may be performed as necessary.

  Thereafter, the rotational speed of the cylindrical mold is increased to a predetermined speed, and when it reaches a desired predetermined speed, it is maintained at a constant speed and continues to rotate. Then, when sufficiently leveled, the silicone fine particles 13 are supplied onto the elastic layer 12. For example, as shown in FIG. 7, a powder supply device 61 and a pressing member 62 are installed on the surface of the intermediate transfer belt 10 in which the elastic layer 12 is laminated on the base layer 11 supported on the peripheral surface of the cylindrical mold 60. To do. While rotating the cylindrical mold 60, the silicone fine particles 13 are uniformly coated on the surface (elastic layer 12) of the intermediate transfer belt 10 from the powder supply device 61, and the silicone fine particles 13 coated on the surface (elastic layer 12) are coated. The pressing member 62 is pressed at a constant pressure. The pressing member 62 removes excess silicone fine particles 13 while embedding the silicone fine particles 13 in the elastic layer 12 (rubber or elastomer). In the present embodiment, since the gold flat sugar-shaped fine particles are used as the silicone fine particles 13, it is possible to form a uniform single particle layer by a simple process such as the leveling process using the pressing member 62. It is.

  The adjustment of the burying rate of the silicone fine particles 13 can be adjusted by the length of the pressing time of the pressing member 32 here. Although the adjustment of the burying rate of the silicone fine particles 13 in the elastic layer 12 may be possible by other methods, it can be easily achieved by, for example, adjusting the pressing force of the pressing member 32. .

  In this way, after the silicone fine particles 13 are uniformly arranged on the surface (elastic layer 12) of the intermediate transfer belt 10, curing (vulcanization) is performed by heating the cylindrical mold 30 at a predetermined temperature for a predetermined time. The elastic layer 12 in which the silicone fine particles 13 are embedded is formed. Then, after sufficiently cooling, the intermediate transfer belt 10 is detached from the cylindrical mold 30 to obtain a desired intermediate transfer belt (seamless belt) 10.

  The method for measuring the burying rate of the silicone fine particles 13 in the intermediate transfer belt 10 is not particularly limited and may be appropriately selected according to the purpose. For example, the cross section of the intermediate transfer belt 10 is scanned with a scanning electron microscope. It can be measured by observing with (SEM).

  The resistance of the intermediate transfer belt 10 manufactured as described above is adjusted by varying the amounts of carbon black and ionic conductive agent. At this time, it should be noted that the resistance is easily changed depending on the size of the silicone fine particles 13 and the occupied area ratio. The resistance can be measured by using a commercially available measuring instrument, for example, by using a Hiresta manufactured by Dia Instruments.

[Image forming apparatus]
The above-described intermediate transfer belt 10 performs primary transfer by superimposing a plurality of toner images formed on the image carrier on the intermediate transfer member, and performs a secondary transfer of the primary transfer image collectively to a recording medium. It can be suitably used as an intermediate transfer belt of a so-called intermediate transfer type image forming apparatus. Hereinafter, the present invention will be described with reference to FIGS. 8 and 9, but the present invention is not limited to this.

  FIG. 8 is a configuration diagram showing the configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 8, the image forming apparatus includes a photosensitive member 200 as an image carrier, a writing optical unit (not shown), an intermediate transfer unit 500, a secondary transfer unit 600, a paper transport device 210, a fixing device 270, and the like. I have. Around the drum-shaped photoconductor 200, a photoconductor cleaning device 201, a static elimination lamp 202, a charging charger 203, a potential sensor 203, a revolver developing unit 230, an image density sensor 205, an intermediate transfer unit 500, and the like are disposed. .

  The writing optical unit performs writing by irradiating the surface of the photosensitive member 200 uniformly charged by the charging charger 203 with the laser beam L based on image information from a scanner or the like (not shown), and statically writing on the surface of the photosensitive member 200. An electrostatic latent image is formed. This image information is single-color image information obtained by decomposing a desired full-color image into black, cyan, magenta, and yellow color information.

  The revolver developing unit 230 includes a developing device 231K using black toner, a developing device 231C using cyan toner, a developing device 231M using magenta toner, and a developing device 231Y using yellow toner. Subscripts K, C, M, and Y indicate black, cyan, magenta, and yellow, respectively. Further, the revolver developing unit 230 includes a developing revolver driving unit (not shown) that rotates the entire developing unit so as to move a predetermined developing unit 231 to a developing position facing the photoreceptor 200.

  The intermediate transfer unit 500 includes an intermediate transfer belt 501 that is an intermediate transfer member. The intermediate transfer belt 501 is stretched around a primary transfer bias roller 507, a belt driving roller 508, a belt tension roller 509, a secondary transfer counter roller 510, a cleaning counter roller 511, and a feedback current detection roller 512. Each roller is made of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. The primary transfer bias roller 507 is applied with a transfer bias controlled to a predetermined current or voltage in accordance with the number of superimposed toner images by a primary transfer power source 801 controlled by constant current or constant voltage. .

  The intermediate transfer belt 501 is driven in the arrow direction by a belt driving roller 508 that is driven to rotate in the arrow direction by a drive motor (not shown). The intermediate transfer belt 501 is set to be larger than the maximum sheet passing size in order to superimpose the toner images formed on the photoreceptor 200.

  The secondary transfer bias roller 605 of the secondary transfer unit 600 is disposed so as to sandwich the transfer paper P, which is a recording medium, between the portion of the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510. The secondary transfer portion is formed. The secondary transfer bias roller 605 is configured to be able to come into contact with and separate from the belt outer peripheral surface of the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 by a contact / separation mechanism (not shown). A transfer bias of a predetermined current is applied to the secondary transfer counter roller 510 by a secondary transfer power source 802 controlled by constant current. Further, a cleaning blade 608 as a cleaning unit is in contact with the secondary transfer bias roller 605. The cleaning blade 608 is for removing the adhering matter adhering to the surface of the secondary transfer bias roller 605 for cleaning.

  A belt cleaning blade 504 for cleaning the intermediate transfer belt 501 and a lubricant application brush 505 for applying a lubricant 506 to the intermediate transfer belt 501 are disposed around the intermediate transfer belt 501 so as to face each other.

  A position detection mark (not shown) is provided on the outer peripheral surface or inner peripheral surface of the intermediate transfer belt 501. However, on the outer peripheral surface side of the intermediate transfer belt 501, it is necessary to devise a position detection mark that avoids the belt cleaning blade 504 passing area, which may be difficult to arrange. In that case, a position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt 501. An optical sensor 514 serving as a mark detection sensor is provided at a position between the primary transfer bias roller 507 and the belt driving roller 508 where the intermediate transfer belt 501 is bridged.

  A registration roller pair 610 is disposed on the upstream side of the secondary transfer unit 600 in the transport direction of the transfer paper P from the secondary transfer unit. The registration roller pair 610 feeds the transfer paper P to the secondary transfer portion between the secondary transfer bias roller 605 and the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 at a predetermined timing. A belt transport device 210 that transports the transfer paper P that has passed through the secondary transfer portion and a fixing device 270 that fixes the toner image on the transfer paper P are located downstream of the secondary transfer portion in the transport direction of the transfer paper P. It is arranged.

  In the image forming apparatus configured as described above, image formation is performed as follows. The photoreceptor 200 is rotated counterclockwise as indicated by an arrow by a drive motor (not shown). On the photoconductor 200, toner images are formed in the order of black, cyan, magenta, and yellow. The intermediate transfer belt 501 is rotated clockwise by the belt driving roller 508 as indicated by an arrow. As the intermediate transfer belt 501 rotates, toner images are formed on the intermediate transfer belt 501 in the order of black, cyan, magenta, and yellow by a transfer bias generated by a voltage applied to the primary transfer bias roller 507. .

  For example, the black toner image is formed as follows. First, the charging charger 203 uniformly charges the surface of the photoreceptor 200 to a predetermined potential with a negative charge by corona discharge. The timing is determined based on the belt mark detection signal, and raster exposure using laser light is performed based on image information by a writing optical unit (not shown). When this raster image is exposed, the charge proportional to the exposure light amount disappears in the exposed portion of the surface of the photoreceptor 200 that is initially uniformly charged, and a K electrostatic latent image is formed. Negatively charged K toner on the developing roller of the developing device 231K comes into contact with this electrostatic latent image. As a result, the toner does not adhere to the remaining portion of the photoconductor 200, and the K toner is adsorbed to the uncharged portion, that is, the exposed portion, to form a K toner image similar to the electrostatic latent image. Is done.

  The black toner image formed on the photoreceptor 200 in this manner is primarily transferred onto the belt outer peripheral surface of the intermediate transfer belt 501 that is rotating at a constant speed while being in contact with the photoreceptor 200. Some untransferred residual toner remaining on the surface of the photoreceptor 200 after the primary transfer is cleaned by the photoreceptor cleaning device 201 in preparation for reuse of the photoreceptor 200. On the photoconductor 200 side, the process proceeds to the cyan image forming process after the black image forming process, and the writing optical unit performs writing with laser light based on the image information, and C electrostatic latent image is formed on the surface of the photoconductor 200. Form an image.

  Then, after the rear end portion of the previous K electrostatic latent image passes and before the front end portion of the C electrostatic latent image arrives, the revolver developing unit 230 is rotated, and the developing unit 231C is moved to the developing position. The C electrostatic latent image is developed with cyan toner. Thereafter, the development of the C electrostatic latent image area is continued. When the rear end portion of the C electrostatic latent image passes, the revolver developing unit 230 is rotated in the same manner as in the case of the developing device 231K, and the next The developing device 231M is moved to the developing position. This is also completed before the leading edge of the next Y electrostatic latent image reaches the developing position. The image forming process for M and Y is not described because the image data reading, electrostatic latent image forming, and developing operations are the same as those for the black and cyan processes described above.

  The K, C, M, and Y toner images sequentially formed on the photosensitive member 200 in this way are sequentially aligned on the same surface on the intermediate transfer belt 501 and are primarily transferred. As a result, a toner image 513 having a maximum of four colors superimposed on the intermediate transfer belt 501 is formed. On the other hand, at the time when the image forming operation is started, the transfer paper P is fed from a paper feed unit such as a transfer paper cassette or a manual feed tray, and is waiting at the nip of the registration roller 610. When the leading edge of the toner image on the intermediate transfer belt 501 approaches the secondary transfer portion, the registration roller 610 is driven so that the leading edge of the transfer paper P coincides with the leading edge of the toner image. Thereby, the transfer paper P is conveyed along the transfer paper guide plate 601, and registration of the transfer paper P and the toner image is performed.

  In this way, when the transfer paper P passes through the secondary transfer portion, the four-color superimposed toner image on the intermediate transfer belt 501 is transferred by the transfer bias applied by the secondary transfer power source 802 to the secondary transfer bias roller 605. Are collectively transferred (secondary transfer) onto the transfer paper P. After the transfer paper P is conveyed along the transfer paper guide plate 601 and passed through a portion facing the transfer paper neutralization charger 606 composed of a static elimination needle disposed on the downstream side of the secondary transfer portion, it is neutralized. Then, it is sent to the fixing device 270 by the belt conveying device 210. Then, after the toner image is melted and fixed at the nip portions of the fixing rollers 271 and 272 of the fixing device 270, the transfer paper P is sent out of the apparatus main body by a discharge roller (not shown), and is stacked face up on a copy tray (not shown). Is done. Note that the fixing device 270 may be configured to include a belt component if necessary.

  On the other hand, the surface of the photosensitive member 200 after the belt transfer is cleaned by the photosensitive member cleaning device 201 and is uniformly discharged by the discharging lamp 202. Further, residual toner remaining on the outer peripheral surface of the intermediate transfer belt 501 after the toner image is secondarily transferred to the transfer paper P is cleaned by the belt cleaning blade 504. The belt cleaning blade 504 is configured to be brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by a cleaning member separating and contacting mechanism (not shown).

  On the upstream side of the belt cleaning blade 504 in the movement direction of the intermediate transfer belt 501, a toner seal member 502 is provided that contacts and separates from the belt outer peripheral surface of the intermediate transfer belt 501. The toner seal member 502 receives the falling toner dropped from the belt cleaning blade 504 when cleaning the residual toner, and prevents the falling toner from scattering on the transfer path of the transfer paper P. The toner seal member 502 is brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 together with the belt cleaning blade 504 by the cleaning member separating and contacting mechanism.

  The lubricant 506 scraped by the lubricant application brush 505 is applied to the outer peripheral surface of the intermediate transfer belt 501 from which the residual toner has been removed in this way. The lubricant 506 is made of, for example, a solid body such as zinc stearate, and is disposed so as to come into contact with the lubricant application brush 505. Further, residual charges remaining on the outer peripheral surface of the intermediate transfer belt 501 are removed by a neutralizing bias applied by a belt neutralizing brush (not shown) that is in contact with the outer peripheral surface of the intermediate transfer belt 501. Here, the lubricant application brush 505 and the belt neutralizing brush are brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by respective contact and separation mechanisms (not shown). .

  Here, at the time of repeat copy, the operation of the scanner and the image formation on the photosensitive member 200 are the first color (K) of the second sheet at a predetermined timing following the image forming process of the fourth color (Y) of the first sheet. ). Further, the intermediate transfer belt 501 has a second K toner image in an area cleaned by the belt cleaning blade 504 on the outer peripheral surface of the belt following the batch transfer process of the first four-color superimposed toner image to the transfer paper. To be primarily transferred. After that, the operation is the same as the first sheet. The above is a copy mode for obtaining a four-color full-color copy. In the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. In the single color copy mode, only the developing device 231 of the predetermined color of the revolver developing unit 230 is set in the developing operation state until the predetermined number of sheets is completed, and the belt cleaning blade 504 is kept in contact with the intermediate transfer belt 501. The copy operation is performed in the state.

  In the above-described embodiment, the copying machine including only one photoconductor has been described. However, in the present invention, for example, as shown in FIG. 9, a plurality of photoconductors are arranged in series along one intermediate transfer belt. The present invention can also be applied to the image forming apparatus. FIG. 9 shows a configuration example of a four-drum type image forming apparatus including four photosensitive members 21K, 21M, 21Y, and 21C for forming toner images of four different colors (black, yellow, magenta, and cyan). FIG. As shown in FIG. 9, the image forming apparatus includes an image forming unit 20, an intermediate transfer unit 30, a paper transport unit 40, a fixing device 50, and the like.

  The image forming unit 20 includes drum-shaped photoreceptors 21K, 21M, 21Y, and 21C that are image carriers for black, magenta, yellow, and cyan. As each photoconductor 21 for each color, an OPC photoconductor is usually used. The image forming unit 20 includes an image writing unit 22 that performs writing by irradiating laser light based on image information of each color of black, magenta, yellow, and cyan. The image writing unit 22 is a laser scanning optical system including, for example, a laser light source, a deflector such as a rotating polygon mirror, a scanning imaging optical system, and a mirror group, and includes four images corresponding to image information of each color. A writing optical path is provided, and image writing corresponding to the image information of each color is performed on the photoconductors 21K, 21M, 21Y, and 21C. Further, around the photosensitive member 21K, a charging device 22K, a developing device 23K, a primary transfer bias roller 24K, a cleaning device 25K, and a photosensitive member discharging device (not shown) are disposed. Similarly, around the photoreceptors 21M, 21Y, and 21C, charging devices 22M, 22Y, and 22C, developing devices 23M, 23Y, and 23C, primary transfer bias rollers 24M, 24Y, and 24C, cleaning devices 25M, 25Y, and 25C, and A photosensitive member neutralizing device (not shown) is disposed. The developing devices 23K, 23M, 23Y, and 23C use a two-component magnetic brush developing system.

  The transfer unit 30 includes an intermediate transfer belt 31 that is stretched by a plurality of rollers 32, 33, and 34 and is rotationally driven in the direction of the arrow in the figure. The intermediate transfer unit 30 sandwiches the intermediate transfer belt 31 between the photoreceptors 21K, 21M, 21C, and 21Y and the primary transfer rollers 24K, 24M, 24C, and 24Y to which a predetermined voltage is applied to form a primary transfer nip. . In addition, the intermediate transfer unit 30 forms a secondary transfer nip by sandwiching the intermediate transfer belt 31 between the secondary transfer backup roller 33 and the secondary transfer roller 41 to which a predetermined voltage is applied. The toner images on the photoconductors 21K, 21M, 21Y, and 21C formed by the image forming unit 20 are sequentially superimposed on the intermediate transfer belt 31 and transferred at the primary transfer nip. The four-color superimposed toner images transferred onto the intermediate transfer belt 31 are collectively transferred onto the transfer paper P at the secondary transfer nip.

  Further, the intermediate transfer unit 30 also includes a cleaning device 35 and a lubricant application device 36 that remove residual toner remaining on the intermediate transfer belt 31. The cleaning device 35 removes residual toner remaining on the intermediate transfer belt 31 without being transferred during the secondary transfer. The lubricant application device 36 includes a solid lubricant and a conductive brush that rubs the intermediate transfer belt 31 to apply the solid lubricant. The conductive brush is always in contact with the intermediate transfer belt 31 and applies a solid lubricant to the intermediate transfer belt 31. The solid lubricant has an effect of improving the cleaning property of the intermediate transfer belt 31, preventing the occurrence of filming, and improving the durability.

  The paper transport unit 40 disposed below the transfer unit 30 in the figure includes a registration roller pair 42 and an endless paper transport belt 43 that is stretched between the secondary transfer roller 41 and the fixing device 50. . The registration roller pair 42 sandwiches the transfer paper P supplied by a paper supply unit (not shown) between the rollers, and sends it to the secondary transfer nip at a timing that can be synchronized with the four-color toner image on the intermediate transfer belt 31. Then, the paper transport unit 40 transports the transfer paper P on which the full color image is transferred through the secondary transfer nip to the fixing device 50.

  In the image forming unit 20 configured as described above, image formation is performed as follows. For example, in the black image forming unit 20K, the surface of the photoconductor 21K uniformly charged by the charging device 22K is irradiated with the laser beam L modulated and deflected by the image writing unit 22 while being scanned. A latent image is formed. The electrostatic latent image on the photoreceptor 21K is developed by the developing device 23K and becomes a black toner image. In the primary transfer nip that faces the primary transfer roller 24K across the intermediate transfer belt 31, the toner image on the photoreceptor 21K is transferred to the transfer paper P. The surface of the photoconductor 21K after the toner image is transferred is cleaned by the photoconductor cleaning device 25K to prepare for the formation of the next electrostatic latent image.

  For the other image forming units 20M, 20C, and 20Y, the above-described image forming process is executed in synchronization with the movement of the intermediate transfer belt 31. On the other hand, the transfer paper P fed from a paper feed unit (not shown) is sent at a predetermined timing by the registration roller pair 42 and conveyed to the secondary transfer nip. Then, the transfer paper P onto which the full-color image is collectively transferred at the secondary transfer nip is transported by the paper transport unit 40 and the toner image is fixed by the fixing device 50. In the single-sided print mode in which an image is formed only on the first surface of the transfer paper P, the transfer paper P sandwiched in the paper discharge nip between the rollers of the paper discharge roller pair 47 is discharged out of the machine as it is. After the toner image is transferred, the intermediate transfer belt 31 is coated with a lubricant by the lubricant application device 36 after the residual toner is removed by the belt cleaning device 35, and prepares for the image formation by the image forming unit 20 again.

  EXAMPLES Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited by these examples, and these examples are appropriately modified without departing from the gist of the present invention. Needless to say, it may be. The layer thickness of the intermediate transfer belt and the burial rate of the fine particles were calculated by observing a cross section at an arbitrary position with a scanning electron microscope (SEM).

[Example 1]
"Preparation of coating solution for base layer"
First, a polyimide varnish (Ube Industries, U-Varnish A and U-Varnish S mixed at a solid content ratio of 60:40) having a polyimide resin precursor as a main component was prepared. A dispersion of carbon black (special black 4 manufactured by Evonik Degussa) previously dispersed in N-methyl-2-pyrrolidone with a bead mill was prepared. And the said dispersion liquid was prepared to the polyimide varnish so that carbon black content rate might be 17 weight% of polyamic acid solid content, and it stirred and mixed well and prepared the coating liquid.

"Production of polyimide base belt"
Next, the outer surface of a metallic cylindrical mold having an outer diameter of 375 mm and a length of 360 mm is roughened by blasting, and the cylindrical coating liquid A is rotated while rotating the cylindrical mold at 50 rpm (times / minute). It apply | coated with the dispenser so that it might cast on the cylindrical outer surface uniformly. When the entire amount of the coating has completely flowed through the cylindrical mold and the coating has spread evenly, the rotational speed of the cylindrical mold is increased to 100 rpm, introduced into a hot air circulating dryer, and gradually heated to 110 ° C. and heated for 60 minutes. did. Further, the temperature is raised and heated at 200 ° C. for 20 minutes, the rotation is stopped, and it is slowly cooled to take out the cylindrical mold on which the formed film is formed, and this is introduced into a heating furnace (firing furnace) capable of high-temperature processing. Specifically, the temperature was raised to 360 ° C. and heat treatment (firing) was performed for 60 minutes. This was sufficiently cooled to obtain a polyimide base layer belt having a layer thickness of 60 μm.

"Production of elastic layer on polyimide base belt"
A rubber composition was prepared by blending and kneading the components shown below in the proportions shown below.
Acrylic rubber (Nipol AR12, manufactured by Nippon Zeon Co., Ltd.) 100 parts by weight Stearic acid (Bead stearic acid Tsubaki, manufactured by NOF Corporation) 1 part by weight Red phosphorus (Nova Excel 140F, manufactured by Rin Chemical Industry Co., Ltd.) 10 parts by weight Aluminum hydroxide (Showa) Heikolite H42M manufactured by Denko Co., Ltd. 40 parts by weight crosslinking agent: hexamethylenediamine carbamate (Diak No. 1 manufactured by DuPont Dow Elastomer Japan Co., Ltd.) 0.6 parts by weight crosslinking accelerator: 70% 1,8-diazabicyclo (5,4 , 0) Salt of undecene-7 and dibasic acid, 30% amorphous silica (VULCOFAC ACT55, manufactured by SAFICA) 0.6 part by weight nitrile rubber (rubber copolymer of acrylonitrile and butadiene) (Nippon Zeon Corporation) Nipol 1042) 1 Part by weight sulfur (200 mesh sulfur manufactured by Tsurumi Chemical Co., Ltd.) 0.1 part by weight Zinc oxide (Zenda Chemical Co., Ltd., two types of zinc white) 0.3 part by weight Vulcanization accelerator (Ouchi Shinsei Chemical Industry / Noxeller CZ) 0.1 parts by weight conductive agent: tetrabutylammonium perchlorate (QAP-01, manufactured by Nippon Carlit Co., Ltd.) 0.3 parts by weight

  Next, the rubber composition thus obtained was dissolved in an organic solvent (MIBK: methyl isobutyl ketone) to prepare a rubber solution having a solid content of 35 wt%. While rotating the cylindrical mold on which the prepared polyimide base layer was formed, the prepared rubber solution was moved to the cylindrical shaft method while continuously discharging the rubber paint from the nozzle onto the polyimide base layer, and then spirally coated. Worked. The amount of coating was such that the final layer thickness at the center was 500 μm. Thereafter, the cylindrical shape coated with the rubber paint was put into a hot air circulating dryer while rotating as it was, heated to 90 ° C. at a temperature rising rate of 4 ° C./min, and heated for 30 minutes.

  Thereafter, the cylindrical mold is taken out of the dryer and cooled, and on this surface, the gold particles in the form of confetti sugar, whose base particles and projections are both polymethylsilsesquioxane (TOSPEARL 150KA manufactured by Momentive Performance Materials) The average particle size of 5.0 μm was uniformly applied to the surface using the method of FIG. 7, and the pressing member of the polyurethane rubber blade was pressed with a pressing force of 100 mN / cm to be fixed to the elastic layer. Subsequently, it was again put into a hot air circulating drier, heated to 170 ° C. at a temperature rising rate of 4 ° C./min, and heat-treated for 60 minutes to obtain an intermediate transfer belt A. The average thickness of the intermediate transfer belt A was 560 μm, and the burying rate of the silicone fine particles was 55%.

[Example 2]
In Example 1, the silicone fine particles on the surface of the elastic layer, the silicon fine particles in the shape of confetti whose base particles are methyl methacrylate crosspolymer and the projections on the surface are polymethylsilsesquioxane (Silcrusta MK03, manufactured by Nikko Rica Co., Ltd.) ) (Average particle size 3.0 μm). Other than this, an intermediate transfer belt B was obtained in the same manner as in Example 1. The average thickness of the intermediate transfer belt B was 560 μm, and the burying rate of the silicone fine particles was 66%.

[Example 3]
An intermediate transfer belt C was obtained in the same manner as in Example 1 except that the thickness of the elastic layer in Example 1 was changed from 500 μm to 300 μm. The average thickness of the intermediate transfer belt C was 360 μm, and the burying rate of the silicone fine particles was 55%.

[Example 4]
In Example 1, the rubber composition used for the elastic layer was changed to the following material and kneaded with a kneader to produce a rubber composition.
Hydrogenated nitrile rubber (Zeppol 2020L, manufactured by ZEON CORPORATION)
100 parts by weight stearic acid (Tsubaki bead stearic acid manufactured by NOF Corporation) 1 part by weight sulfur (200 mesh sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.) 1 part by weight zinc oxide (2 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.) 5 parts by weight Sulfur accelerator: Tetramethylthiuram monosulfide (Noxeller TS manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts by weight Red phosphorus (Rin Chemical Industry Co., Ltd. Nova Excel 140F 10 parts by weight Aluminum hydroxide (Showa Denko Co., Ltd.) Heidilite H42M) 40 parts by weight

  An intermediate transfer belt D was obtained in the same manner as in Example 1 except that the rubber composition was used for the elastic layer. The average thickness of the intermediate transfer belt D was 610 μm, and the burying rate of the silicone fine particles was 75%.

[Example 5]
In Example 1, the polyimide base layer belt was changed to the following materials.
"Preparation of coating solution for base layer"
First, a polyamide-imide varnish (Viromax HR-16NN manufactured by Toyobo Co., Ltd.) was prepared. To this, a dispersion of carbon black (MA77 manufactured by Mitsubishi Chemical Corp.) dispersed in N-methyl-2-pyrrolidone in advance by a bead mill is used so that the carbon black content is 24% by weight of the solid content of polyamideimide varnish. The mixture was mixed well and stirred and mixed to prepare a coating solution.

"Preparation of polyamideimide base belt"
Next, the outer surface of a metal cylindrical mold having an outer diameter of 375 mm and a length of 360 mm is roughened by blasting, and each of the coating liquids is applied to the outer cylindrical surface while rotating the cylindrical mold at 50 rpm (times / minute). It was applied with a dispenser so as to be cast uniformly. When the predetermined amount was completely poured and the coating film was spread evenly, the number of revolutions was increased to 100 rpm, introduced into a hot air circulating dryer, gradually heated to 110 ° C. and heated for 60 minutes. Further, the temperature is raised and heated at 200 ° C. for 20 minutes, the rotation is stopped, and it is slowly cooled to take out the cylindrical mold on which the formed film is formed, and this is introduced into a heating furnace (firing furnace) capable of high-temperature processing. In particular, the temperature was raised to 250 ° C. and heat treatment (firing) was performed for 60 minutes. After sufficiently cooling, a polyamideimide base layer belt having a layer thickness of 60 μm was obtained. Thereafter, an intermediate transfer belt E was obtained in the same manner as in Example 1. The average thickness of the intermediate transfer belt E was 560 μm, and the burying rate of the silicone fine particles was 55%.

[Comparative Example 1]
In Example 1, from a saccharose-shaped silicone fine particle (TOSPEARL 150KA) on the surface of the elastic layer to a true spherical silicone fine particle (TOSPEARL 145A manufactured by Momentive Performance Materials Co., Ltd.) (average particle size 4. 5 μm). Other than this, an intermediate transfer belt F was obtained in the same manner as in Example 1. The average thickness of the intermediate transfer belt F was 560 μm, and the burying rate of the silicone fine particles was 50%.

[Comparative Example 2]
In Example 1, the fine particles on the elastic layer surface were changed to polymethylsilsesquioxane amorphous particles (TOSPEARL 240, manufactured by Momentive Performance Materials) (average particle size: 4.0 μm). Other than this, an intermediate transfer belt G was obtained in the same manner as in Example 1. The average thickness of the intermediate transfer belt G was 560 μm. When the cross section of the intermediate transfer belt G was observed with an electron beam microscope, the embedding of the fine particles could be observed. There was unevenness, and a clear burial rate could not be obtained.

The intermediate transfer belts A to G of the above examples and comparative examples were mounted on a commercially available image forming apparatus (image MP C7501; manufactured by Ricoh), and the following various evaluations were performed.
(1) Measurement of initial transfer rate As the transfer paper, use paper that has a Japanese paper-like pattern on its surface (Rezac 66 260kg paper manufactured by Tokai Paper Co., Ltd.), and output a blue solid image on it. did. Then, the amount of image toner on the intermediate transfer belt before transfer to paper and the amount of toner remaining on the intermediate transfer belt after transfer to paper were measured, and the secondary transfer rate was calculated.
Secondary transfer rate (%) = {[toner amount on intermediate transfer belt after transfer (g)] / [toner amount on intermediate transfer belt before transfer (g)]} × 100
(2) Measurement of transfer rate at the time of continuous image output of 300,000 sheets After outputting 300,000 continuous images of blue solid images, the transfer was stopped, and the secondary transfer rate was measured according to the method of (1) above. These results are shown in Table 1.

  From the results in Table 1, it can be seen that in the intermediate transfer belt A to the intermediate transfer belt E of Examples 1 to 5, a high transfer rate was obtained both in the initial transfer rate and after the continuous sheet passing. On the other hand, although the intermediate transfer belt F of Comparative Example 1 has a high initial transfer rate, fine particles are detached by continuous paper passing, and the transfer rate after continuous paper passing is lowered. Further, since the intermediate transfer belt G of Comparative Example 2 has unevenness in the degree of embedding of the fine particles depending on the location, not only the transfer rate is low from the initial stage, but also the fine particles are detached due to continuous paper passing. The transfer rate has dropped significantly.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
In an intermediate transfer body such as the intermediate transfer belt 10 in which at least a base layer such as the base layer 11 and an elastic layer such as the elastic layer 12 are laminated, the surface of the elastic layer has a concavo-convex shape due to silicone fine particles such as silicone fine particles 13, The silicone fine particles have a plurality of protrusions uniformly on the surface of the spherical base particles.
According to this, as described in the above embodiment, since the silicone fine particles have a so-called confetti shape having a plurality of protrusions on the entire surface of the base particle, adhesion to the elastic layer (anchor effect) is achieved. High transfer performance can be maintained over a long period of time. Further, as can be seen from the results of the above-described embodiments, the silicone fine particles can be formed and evenly arranged in a single particle layer, rather than being unevenly arranged in an aggregated state on the elastic layer. . For this reason, there is little variation in transfer performance such as different transfer performance depending on the location, and high transfer performance can be exhibited.
(Aspect B)
In the intermediate transfer member of (Aspect A), a single particle layer is formed by the silicone fine particles.
According to this, since the single particle layer in which the silicone fine particles are uniformly arranged is formed as described in the above embodiment, there is little variation in the transfer performance such as different transfer performance depending on the location, and high transfer performance. Can be demonstrated. Moreover, since the adhesiveness of the silicone fine particles to the elastic layer is high, even if the silicone fine particles are a single particle layer, it is possible to suppress the transfer performance from being reduced due to the removal of the fine particles.
(Aspect C)
In the intermediate transfer member of (Aspect A) or (Aspect B), both the base particle and the protrusion are polymethylsilsesquioxane.
According to this, as described in the above embodiment, polymethylsilsesquioxane is excellent in releasability and can exhibit high transfer performance. In addition, polymethylsilsesquioxane is less likely to damage an image carrier such as an organic photoreceptor than inorganic particles such as silica particles, and can improve the durability of the image carrier.
(Aspect D)
In the intermediate transfer member of (Aspect A) or (Aspect B), the silicone fine particles have a base particle of a methyl methacrylate crosspolymer and a protrusion of polymethylsilsesquioxane.
According to this, as described in the above embodiment, methyl methacrylate crosspolymer and polymethylsilsesquioxane are excellent in releasability and can exhibit high transfer performance. In addition, methyl methacrylate crosspolymer and polymethylsilsesquioxane are less likely to damage an image carrier such as an organic photoconductor than inorganic particles such as silica particles, and can improve the durability of the image carrier. .
(Aspect E)
(Aspect A) (Aspect B) In the intermediate transfer member of (Aspect C) or (Aspect D), the elastic layer has a thickness in the stacking direction of 400 μm or more.
According to this, as described in the above embodiment, high transfer performance can be exhibited regardless of the type of recording medium and the surface properties, such as being able to cope with uneven paper types.
(Aspect F)
(Aspect A) (Aspect B) (Aspect C) In the intermediate transfer member of (Aspect D) or (Aspect E), the base layer is a polyimide resin or a polyamideimide resin.
According to this, since the polyimide resin and the polyamide-imide resin have a high elastic modulus and high heat resistance as described in the above embodiment, they can be suitably used as the base layer.
(Aspect G)
(Aspect A) (Aspect B) (Aspect C) (Aspect D) In the intermediate transfer member of Aspect E or Aspect F, the intermediate transfer belt is a seamless belt.
According to this, as described in the above embodiment, the intermediate transfer member that is a seamless belt does not need to perform transfer while avoiding joints, and can perform high-speed transfer.
(Aspect H)
An image carrier, a developing unit for developing the latent image formed on the image carrier with toner, a primary transfer unit for transferring the toner image developed on the image carrier to an intermediate transfer member, and an intermediate transfer In an image forming apparatus including a secondary transfer unit that transfers a toner image transferred onto a body to a recording medium, (Aspect A) (Aspect B) (Aspect C) (Aspect D) (Aspect) E) The intermediate transfer member of (Aspect F) or (Aspect G) is used.
According to this, since the intermediate transfer body that can maintain high transfer performance over a long period of time is used as described in the above embodiment, a high-quality image can be obtained over a long period of time.
(Aspect I)
In the image forming apparatus of (Aspect H), a plurality of image carriers that carry toner images of different colors are arranged in series.
According to this, as described in the above embodiment, it is possible to perform high-speed transfer as compared with the case where a plurality of developing units are installed for one image carrier.

10, 31, 501 Intermediate transfer belt 11 Base layer 12 Elastic layer 13 Silicone fine particle 20 Image forming unit 21, 200 Photoreceptor 30, 500 Intermediate transfer unit 31, 501 Intermediate transfer belt 40, 600 Secondary transfer unit 50, 270 Fixing device 60 Cylindrical type 61 Powder supply device 62 Pressing member

JP-A-9-230717 JP 2002-162767 A Japanese Patent No. 4430892 JP 2007-328165 A JP 2009-75154 A JP 2008-191225 A Japanese Patent No. 3874360

Claims (9)

In the intermediate transfer member in which at least the base layer and the elastic layer are laminated,
The surface of the elastic layer has an irregular shape with silicone fine particles,
The intermediate transfer member, wherein the silicone fine particles have a plurality of protrusions uniformly on the surface of the spherical base particles. The intermediate transfer member according to claim 1,
A single particle layer is formed by the silicone fine particles. The intermediate transfer member according to claim 1 or 2,
The intermediate transfer member, wherein the silicone fine particle is a polymethylsilsesquioxane in both of the base particle and the protrusion. The intermediate transfer member according to claim 1 or 2,
The intermediate transfer member, wherein the silicone fine particles have a base particle of methyl methacrylate crosspolymer and a protrusion of polymethylsilsesquioxane. In the intermediate transfer member according to claim 1, 2, 3, or 4,
An intermediate transfer member having a thickness in the stacking direction of 400 μm or more. In the intermediate transfer member according to claim 1, 2, 3, 4 or 5,
The intermediate transfer member, wherein the base layer is a polyimide resin or a polyamideimide resin. In the intermediate transfer member according to claim 1, 2, 3, 4, 5 or 6,
An intermediate transfer member characterized by being a seamless belt. An image carrier, a developing unit for developing the latent image formed on the image carrier with toner, a primary transfer unit for transferring the toner image developed on the image carrier to an intermediate transfer member, and an intermediate transfer In an image forming apparatus comprising secondary transfer means for transferring a toner image transferred onto a body to a recording medium,
An image forming apparatus using the intermediate transfer member according to claim 1, 2, 3, 4, 5, 6, or 7 as the intermediate transfer member. The image forming apparatus according to claim 8.
An image forming apparatus, wherein a plurality of image carriers that carry toner images of different colors are arranged in series.