JP2014145817A - Intermediate transfer belt, image forming apparatus, and manufacturing method of intermediate transfer belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an intermediate transfer belt for achieving an electrophotographic device with high durability and high image quality that has flexibility and excellent toner releasability, can achieve a high transfer rate irrespective of the type of a transfer medium, is sustainable for a long period, and causes no damage to an organic photoreceptor.SOLUTION: An intermediate transfer belt has a toner image transferred thereto that is obtained by developing a latent image formed on an image carrier with toner, and includes a base layer 11, and an elastic layer 12 laminated on the base layer 11. The elastic layer 12 contains an elastic body and spherical resin particles 13, and has a concave-convex shape formed on the surface; and the spherical resin particles 13 are formed of two or more types of spherical particles having different frictional electrostatic charging series.

Description

  The present invention relates to an intermediate transfer belt such as a seamless belt provided in an image forming apparatus such as a copy or printer, an image forming apparatus using the same, and a method for manufacturing the intermediate transfer belt.

  Conventionally, seamless belts have been used as members for various uses in electrophotographic apparatuses. Particularly in recent full-color electrophotographic apparatuses, an intermediate transfer belt system in which developed images of four colors of yellow, magenta, cyan, and black are once overlaid on an intermediate transfer medium, and then collectively transferred to a transfer medium such as paper. Is used.

  Such an intermediate transfer belt system has been used in a system that uses four color developing devices for one photoconductor, but has a drawback in that the printing speed is slow. For this reason, as a high-speed print, a four-tandem tandem method is used in which the photoreceptors are arranged for four colors and each color is continuously transferred to paper. However, in this method, there are fluctuations due to the environment of the paper, etc., and it is very difficult to match the position accuracy of overlapping each color image, causing a color misregistration image. Therefore, in recent years, it has become the mainstream to adopt the intermediate transfer method for the quadruple tandem method.

  Under such circumstances, the required characteristics (high-speed transfer, positional accuracy) of the intermediate transfer belt are also stricter than before, and it is necessary to satisfy the characteristics corresponding to these requirements. Yes. In particular, for positional accuracy, it is required to suppress fluctuation due to deformation such as elongation of the belt itself due to continuous use. Further, the intermediate transfer belt is laid out over a wide area of the apparatus, and is required to be flame retardant because a high voltage is applied for transfer. In order to meet such requirements, polyimide resins, polyamideimide resins, and the like that are high elastic modulus and high heat resistance resins are mainly used as intermediate transfer belt materials.

  However, since the intermediate transfer belt made of polyimide resin has high strength and high surface hardness, a high pressure is applied to the toner layer when the toner image is transferred, and the toner locally aggregates and a part of the image is formed. A so-called hollow image that is not transferred may occur. In addition, contact followability with a contact member at a transfer portion such as a photoconductor or paper is inferior, so that a partial contact failure portion (gap) may occur in the transfer portion, and transfer unevenness may occur.

  In recent years, full-color electrophotography has been used to form images on various types of paper. In addition to ordinary smooth paper, recycled paper and embossed paper can be used not only from smooth paper but also from slippery and highly smooth paper such as coated paper. Roughly surfaced materials such as Japanese paper and kraft paper are increasingly used. Such followability to papers having different surface properties is important. If the followability is poor, uneven unevenness of color and uneven color tone occur. In order to solve this problem, various intermediate transfer belts in which a relatively flexible layer is laminated on a base layer have been proposed.

  However, when the surface layer is a relatively flexible layer, the transfer pressure is reduced and the followability to paper irregularities is improved, but the toner cannot be released well due to the poor surface releasability. There is a problem that transfer efficiency is lowered and the former effect cannot be utilized. There is also a problem that it is inferior in wear resistance and scratch resistance.

  In order to solve this problem, there is a method of newly providing a protective layer, but when coated with a material with sufficiently high transfer performance, there is a problem that the flexibility of the flexible layer cannot be followed and cracking or peeling occurs. Since it occurs, it is not preferable. Therefore, as a method for protecting a flexible surface layer without causing the above-described problems, proposals have been made to improve transferability by attaching fine particles to the surface.

  Patent Document 1 proposes coating with beads having a diameter of 3 μm or less. However, the formation of this publication is not sufficient in terms of durability required for recent electrophotographic apparatuses because particles are detached.

  In Patent Documents 2 and 3, it is proposed to form a layer with a material having affinity for the hydrophobized fine particles. In these, particles having a very small particle size are preferably used. However, the particle layer is thick, or there are non-uniform portions due to particle aggregation, resulting in variations in transfer performance, and a product that can satisfy the high level of image quality required of recent electrophotographic devices can be obtained. Absent.

  Patent Documents 4 and 5 propose a configuration that realizes durability by using relatively large particles and embedding in resin to some extent. However, even in this proposal, non-uniformity occurs in the presence of particles, and it is impossible to obtain a product that can satisfy the high level of image quality required for recent electrophotographic apparatuses.

  In all of Patent Documents 1 to 5, silica is preferably used. However, since silica particles have a strong cohesive force, a uniform particle layer cannot be formed as described above. In addition, inorganic particles such as silica tend to scratch and wear the surface of the organic photoreceptor due to contact with the organic photoreceptor that is preferably used as a latent image carrier for image formation, and reduce durability. This causes the problem of

  Patent Document 6 proposes a method of coating the elastic layer surface using silicone resin particles. Since the silicone resin particles are excellent in toner releasability, it is considered that a certain level of image quality can be obtained. However, silicone resin is a material that is very easily negatively charged. Currently, negatively charged toner is often used in electrophotographic systems. However, when a negatively charged toner comes into contact with an intermediate transfer belt having a surface covered with a silicone resin, the negative charge of the toner is reduced. It moves to the silicone resin particles that are more likely to be negatively charged, and the chargeability of the toner is weakened. As a result, the force for moving the toner by the electric field during the secondary transfer is weakened, resulting in a problem that transferability is lowered.

The present invention has been made in view of the above prior art, is flexible and excellent in toner releasability, can realize a high transfer rate regardless of the transfer medium, and can be sustained for a long time. An object of the present invention is to obtain an intermediate transfer belt for realizing an electrophotographic apparatus having high durability and high image quality without causing any damage to the organic photoreceptor.
Hereinafter, the “electrophotographic apparatus” may be referred to as an “image forming apparatus”.

  As a result of intensive studies, the present inventors have found that an uneven shape is formed on the surface of the elastic layer in the intermediate transfer belt onto which the toner image obtained by developing the latent image formed on the image carrier with toner is transferred. Thus, it has been found that the above problem can be solved by using specific spherical particles as the spherical particles.

  That is, the present invention relates to an intermediate transfer belt to which a toner image obtained by developing a latent image formed on an image carrier with toner is transferred, and includes a base layer and an elastic layer laminated on the base layer And the elastic layer contains an elastic body and spherical particles, and has an uneven surface formed on the surface, and the spherical particles are composed of two or more different types of triboelectric series. It is a transfer belt.

  According to the present invention, intermediate transfer used in a highly durable and high-quality image forming apparatus that can maintain high transfer performance not only in the initial stage but also in the long term, regardless of the type and surface properties of the transfer medium. A belt can be provided.

FIG. 3 is a schematic diagram illustrating a layer configuration example of an intermediate transfer belt in the present invention. The enlarged schematic diagram which observed an example of the surface of the intermediate transfer belt in this invention from right above is shown. In FIG. 2, the enlarged schematic diagram which observed the surface of the belt at the time of distinguishing a 1st particle and a 2nd particle from right above is shown. FIG. 2 shows a schematic diagram of a cross section of an intermediate transfer belt having a surface layer containing a plurality of particles. The schematic diagram of the apparatus for apply | coating the base layer and elastic layer in this invention is shown. The schematic diagram of the apparatus for apply | coating and fixing the spherical particle (powder particle) in this invention is shown. FIG. 3 is a schematic view of a main part for explaining an image forming apparatus equipped with an intermediate transfer belt according to the present invention. FIG. 3 is a schematic diagram of a main part showing a configuration example of an image forming apparatus in which a plurality of photosensitive drums are arranged in parallel along one intermediate transfer belt according to the present invention.

  The intermediate transfer belt according to the present invention is an intermediate transfer belt to which a toner image obtained by developing a latent image formed on an image carrier with toner is transferred. The intermediate transfer belt is formed on a base layer 11 and the base layer 11. And the elastic layer 12 contains an elastic body and spherical particles 13 and has a concavo-convex shape formed on the surface thereof. The spherical particles 13 are different in the triboelectric charging series. It consists of more than one type.

  In an image forming apparatus, a seamless belt is used for several members. An intermediate transfer member (intermediate transfer belt) is one of important members that require electrical characteristics. The intermediate transfer belt used in the image forming apparatus of the present invention will be described below. Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

  FIG. 1 shows a layer structure of an intermediate transfer belt preferably used in the present invention. However, it is not limited to this configuration. As a configuration, a flexible elastic layer 12 is laminated on a rigid base layer 11 that can be relatively flexible. On the outermost surface of the elastic layer 12, spherical particles 13 made of two or more types of spherical particles having different frictional charge series are arranged (embedded) in the surface direction independently on the elastic layer to form a uniform uneven shape. Yes.

(Base layer)
First, the base layer 11 will be described. Examples of the constituent material include a material containing a filler (or additive) for adjusting electric resistance in the resin, that is, a so-called electric resistance adjusting material. Examples of such resins include fluorine resins such as PVDF (polyvinylidene fluoride) and ETFE (ethylene / tetrafluoroethylene copolymer), polyimide resins, and polyamideimide resins from the viewpoint of flame retardancy. In view of mechanical strength (high elasticity) and heat resistance, polyimide resin or polyamideimide resin is particularly preferable.

  As polyimide and polyamideimide in the present invention, general-purpose products from manufacturers such as Toray DuPont, Ube Industries, Nippon Nippon Chemical, JSR, Unitika, IST, Hitachi Chemical, Toyobo, Arakawa Chemical, etc. are obtained. Can be used.

Examples of the electrical resistance adjusting material include a 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 tetraalkyl ammonium salt, trialkyl benzyl ammonium salt, alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate, glycerol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, and polyoxyethylene fatty acid. Alcohol ester, alkyl betaine, lithium perchlorate, etc. are mentioned, and these may be used in combination.
The electrical resistance adjusting material in the present invention is not limited to the above exemplary compounds.

  Further, in the method for producing the intermediate transfer belt of the present invention, the coating liquid contains a resin component, and if necessary, further contains a dispersion aid, a reinforcing material, a lubricant, a heat conductive material, an antioxidant, and the like. May be.

The electrical resistance adjusting material contained in the seamless belt suitably equipped as the intermediate transfer belt is preferably 1 × 10 ⁸ to 1 × 10 ¹³ Ω / □ in surface resistance and 1 × 10 ⁶ to 1 × in volume resistance. The amount is set to 10 ¹² Ω · cm, but it is necessary to select and add an amount in a range where the molded film is brittle and does not easily break from the viewpoint of mechanical strength. In other words, in the case of an intermediate transfer belt, an electrical characteristic (for example, a coating liquid in which the blending of the resin component (for example, a polyimide resin precursor or a polyamideimide resin precursor) and an electrical resistance adjusting material is appropriately adjusted is used. It is preferable to manufacture and use a seamless belt having a balance between surface resistance and volume resistance) and mechanical strength.

In the case of carbon black, the content of the electric resistance adjusting material in the present invention is 10 to 25 wt%, preferably 15 to 20 wt% of the total solid content in the coating liquid.
Moreover, as content in the case of a metal oxide, it is 1-50 wt% of the total solid of a coating liquid, Preferably it is 10-30 wt%. If the content is less than the range of the respective electric resistance adjusting materials, the effect cannot be sufficiently obtained, and if the content is greater than the respective range, the mechanical strength of the intermediate transfer belt (seamless belt) decreases. This is not preferable for practical use.

  There is no restriction | limiting in particular as thickness of the said base layer, 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 material layer is less than 30 μm, the belt may be easily torn due to cracks, and if it exceeds 150 μm, the belt may be broken by bending. On the other hand, when the thickness of the base layer is within the particularly preferable range, it is advantageous in terms of durability. With respect to the base layer, it is preferable to eliminate film thickness unevenness as much as possible in order to improve running stability.

  The method for adjusting the thickness of the base layer is not particularly limited and may be appropriately selected depending on the purpose. For example, measurement with a contact-type or eddy-current film thickness meter or scanning of a cross section of the film with a scanning electron The method of measuring and adjusting with a microscope (SEM) is mentioned.

(Elastic layer)
Next, the elastic layer 12 laminated on the base layer 11 will be described. The elastic layer 12 is laminated on the base layer 11, contains an elastic body and spherical particles 13 described later, and has an uneven shape on the surface. More specifically, the elastic layer 12 is formed by laminating an elastic body on the base layer 11, and spherical particles 13 are arranged in the surface direction on the surface of the elastic layer 12.

  As a material constituting the elastic body, materials such as general-purpose resins, elastomers, and rubbers can be used. However, a material having sufficient flexibility (elasticity) to sufficiently exhibit the effects of the present invention is used. It is preferable to use an elastomer material or a rubber material.

  Examples of the elastomer material include thermoplastic elastomers such as polyester, polyamide, polyether, polyurethane, polyolefin, polystyrene, polyacryl, polydiene, silicone-modified polycarbonate, and fluorine copolymer. . Examples of thermosetting include polyurethane, silicone-modified epoxy, and silicone-modified acrylic.

  Examples of the rubber material include 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. .

  A material capable of obtaining performance is appropriately selected from the various elastomers and rubbers. In particular, it is preferable to select a soft material as much as possible in order to follow the surface state of a paper such as a resack paper having irregularities in the surface properties of the paper as a transfer medium (transfer material).

  In the present invention, in order to form a spherical particle layer on the surface of this material, a thermosetting material is preferable to a thermoplastic material. The thermosetting material is excellent in adhesiveness with the resin particles due to the effect of the functional group contributing to the curing reaction, and can be reliably fixed. Vulcanized rubber is likewise preferred.

  In the present invention, acrylic rubber is most preferred from the viewpoints of ozone resistance, flexibility, adhesion to spherical fine particles, imparting flame retardancy, and environmental stability. Hereinafter, the acrylic rubber will be described.

  The acrylic rubber which is the rubber elastic layer of the present invention 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, and N, N′-dicinnamylidene-1,6-hexane diamine.
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, a crosslinked material will become hard too much and the elasticity etc. as a crosslinked rubber will be impaired.

In the acrylic rubber elastic layer of the present invention, 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 a guanidine compound, an imidazole compound, a quaternary onium salt, a polyvalent tertiary amine compound, a tertiary phosphine compound, and an alkali metal salt of a weak acid.
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 alkali metal salt of a weak acid 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 remarkably reduced, or the elongation change or the tensile strength change after heat load 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 to 220 ° C, more preferably 140 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 is preferably performed for 1 to 48 hours, although it varies depending on the heating method, crosslinking temperature, shape, and the like. What is necessary is just to select the heating method and heating temperature at the time of post-crosslinking suitably.

  To the selected material, an electrical resistance adjusting agent for adjusting electrical characteristics, a flame retardant for obtaining flame retardancy, and materials such as an antioxidant, a reinforcing agent, a filler, and a crosslinking accelerator, as necessary. Mixing appropriately included.

  Furthermore, as the electric resistance adjusting agent for adjusting the electric characteristics, the above-described various materials can be applied. However, since carbon black, metal oxide, and the like impair flexibility, it is preferable to suppress the amount used, It is also effective to use an agent or a conductive polymer. Moreover, you may use these together.

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 is preferably adjusted so that the surface resistance is 1 × 10 ⁸ to 1 × 10 ¹³ Ω / □ and the volume resistance is 1 × 10 ⁶ to 1 × 10 ¹² Ω · cm. .

  Further, in order to obtain a high uneven paper transfer property as required in recent electrophotographic apparatuses, the flexibility of the elastic layer 12 is such that the micro rubber hardness value in an environment of 23 ° C. and 50% RH is 35 or less. preferable. In so-called microhardness measurements such as Martens hardness and Vickers hardness, only the hardness in the bulk direction of the measurement site, that is, the hardness in the vicinity of the very surface, is measured, so the deformation performance of the entire belt cannot be evaluated. For this reason, for example, when a flexible material is brought to the outermost surface in a configuration having a low deformation performance as the entire intermediate transfer belt, the micro hardness value becomes low. Such a belt has low deformation performance, that is, poor followability to the uneven paper, and as a result, the transfer performance to the uneven paper required recently is insufficient. Therefore, it is preferable to measure the micro rubber hardness that can evaluate the deformation performance of the entire belt.

  As a film thickness of the elastic layer 12, about 200 micrometers-2 mm are preferable, and 400 micrometers-1000 micrometers are more preferable. If the film thickness is thin, the followability to the surface properties of the transfer medium and the effect of reducing the transfer pressure are low, which is not preferable. If it is too thick, the film becomes heavier and more likely to bend, resulting in instability in running performance, and because cracks are likely to occur due to bending at the roller curvature portion for stretching the belt, such being undesirable. In addition, as a measuring method of the said thickness, it can measure by observing a cross section with a scanning microscope (SEM).

(Spherical particles)
Next, the spherical particles 13 formed on the surface of the elastic body will be described. In the present invention, spherical particles composed of two or more types having different frictional charging series are used as the spherical particles 13 formed on the surface of the elastic layer. Here, a case where two types of spherical particles are used will be described.

  Examples of the material of the spherical particles include spherical particles mainly composed of a resin such as acrylic resin, melamine resin, polyamide resin, polyester resin, silicone resin, and fluorine resin. Further, the surface of particles made of these resin materials may be subjected to surface treatment with a different material. The resin particles referred to here include a rubber material. A configuration in which spherical particles made of a rubber material are coated with a hard resin to form spherical particles is also applicable. Moreover, it may be hollow or porous.

  Among these resins, silicone resin particles are most preferred as those having a slipperiness and a high function capable of imparting releasability to toner and abrasion resistance. It is preferable that the resin is a particle formed into a spherical shape by a polymerization method or the like using these resins. In the present invention, a particle closer to a true sphere is more preferable.

  However, materials having excellent releasability with respect to toner, such as the silicone resin described above, are often materials that are easily negatively charged in the charging series, and currently, negatively charged toners are sometimes used in electrophotographic systems. Many. However, when a negatively charged toner and an intermediate transfer belt having a surface covered with a resin that is easily negatively charged come into contact with the toner, the negative charge of the toner moves to resin particles that are more likely to be negatively charged. Will be weakened. As a result, the force for moving the toner by the electric field during the secondary transfer is weakened, resulting in a problem that transferability is lowered.

  Therefore, the inventors of the present invention used particles of a material excellent in toner releasability as the first particles, and particles of a material that is more easily positively charged as the second particles when comparing charged series than the first particles. Invented to combine. By disposing the second particles made of a material that is more positively charged than the first particles together with the first particles having excellent toner releasability on the surface of the elastic layer 12, the negative charge of the toner is excessively increased. Further, it is possible to prevent the toner from being taken to the intermediate transfer belt side, and it is possible to prevent the force for moving the toner by the electric field during the secondary transfer from being weakened.

  As the first particles, silicone resin particles are particularly preferably used as described above. Further, as the second particles, particles having the above-described materials can be used as long as they are materials that are easily positively charged when compared with the first particles. In view of releasability, acrylic resin particles are particularly preferably used.

Furthermore, it is preferable that the particle diameters of the first particles and the second particles are as close as possible. Specifically, it is preferable that the difference between the volume average particle diameters of the respective particles is within 0.5 μm.
In the case of a plurality of types of spherical particles, the difference between the volume average particle size of the particle type having the largest volume average particle size and the particle type having the smallest volume average particle size is within 0.5 μm. Is preferred.

  The spherical particles 13 preferably have a volume average particle size of 1.0 μm to 5.0 μm. When the particle size is less than 1.0 μm, the transfer performance effect by the particles cannot be sufficiently obtained. On the other hand, if it is larger than 5.0 μm, the surface roughness becomes large and the gaps between the particles become large, so that there is a problem that the toner cannot be transferred well or the cleaning is poor. In addition, since many particles have high insulating properties, if the particle size is too large, residual charging potential due to the particles causes image disturbance due to accumulation of this potential during continuous image output.

(Surface condition of the belt)
Next, the belt surface state in the present invention will be described. FIG. 2 shows an enlarged schematic view of the belt surface observed from directly above. Thus, it is preferable that spherical particles are not agglomerated and each particle is isolated. Almost no overlap between the resin particles is observed. The diameter of the cross section of each particle constituting the surface on the elastic body surface is preferably uniform, and specifically, the distribution width is preferably ± (average particle diameter × 0.5) μm or less. In order to form this, it is preferable to use particles having a uniform particle size as much as possible, but the particle size distribution can be obtained by forming a surface by a method in which particles having a certain particle size can be selectively formed on the surface without using this. It is good also as a structure used as a width | variety.

In the present invention, two or more kinds of spherical particles are used as the spherical particles. The first particles made of a material having excellent toner releasability existing on the surface of the elastic layer 12 and the charged series more than the first particles. Regarding the projected area ratio with the second particles of a material that is easily positively charged when compared, the projected area ratio of the first particles is in the range of 60% to 95% with respect to the projected area ratio of the entire spherical particles. It is preferable to be within. When the projected area ratio of the first particles is less than 60%, there is a problem in that the excellent properties of the first particles in terms of toner releasability are not sufficiently exhibited and sufficient transferability cannot be obtained. In addition, when the projected area ratio of the first particles exceeds 95%, the amount of the second particles that suppress the change in the charging characteristics of the toner is relatively reduced, so that the effect intended by the present invention is achieved. Not enough.
Therefore, in the present invention, silicone resin particles are preferably used as the first particles, but when silicone resin particles are used, the projected area ratio of the silicone resin particles is 60% or more with respect to the projected area ratio of the entire spherical particles. , Preferably in the range of 95% or less.

  FIG. 3 shows an enlarged schematic view of the surface of the belt observed from directly above when the first particles and the second particles are distinguished. In this way, the second particles are sparsely present while the first particles dominate. As a forming method, a powder in which the first particles and the second particles are sufficiently mixed in advance at a desired ratio is directly applied on the elastic body as it is, and then it can be easily and uniformly aligned. it can. The timing at which the particles are applied to the surface of the elastic layer is not particularly limited, and can be any before or after crosslinking of the rubber.

  Regarding the projected area ratio of the exposed portion of the elastic body and the exposed portion of the particle, the projected area ratio of the exposed portion of the particle is preferably 60% or more. If it is less than 60%, the area where the elastic body is exposed without being covered with particles becomes large, the toner and the elastic body come into contact with each other, and good toner transferability cannot be obtained, and residual toner cleaning and filming resistance Is significantly reduced.

  In the present invention, the spherical particles take a form of being partially embedded in the elastic layer, and the burying rate is preferably more than 50% and less than 100%, preferably 51% to 90%. Is more preferable. If it 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, 100% is not preferable because the effect of the particles on the transferability is reduced.

  The burial rate is the rate of burial in the resin layer having a diameter in the depth direction of the particles, but the burial rate here means that all particles exceed 50% and do not reach 100%. Instead, the numerical value expressed by the average burial rate when viewed from a certain field of view should be more than 50% and less than 100%. However, when the burial rate is 50%, in the cross-sectional observation by the electron microscope, the particles completely buried in the elastic layer are hardly observed (the number% of the particles completely buried in the elastic layer is the total number of particles). (5% or less).

  In addition, the spherical particles 13 are arranged in a plane direction on the surface of the elastic layer 12, and the particles are preferably formed as a single layer in the thickness direction with respect to the elastic layer. As shown in FIG. 4, in the configuration including a plurality of particles in the thickness direction, the distribution of the particles becomes uneven, and the electrical characteristics of the belt surface become non-uniform due to the influence of the electric resistance value of the particles. Disturbs. Specifically, the electrical resistance value in the portion where many particles are present becomes high, a surface potential is generated due to the residual charge, and the surface potential varies on the belt surface, resulting in the image density in the adjacent portion. Image disturbance due to a difference or the like becomes obvious.

(Method for manufacturing intermediate transfer belt)
Next, an example of a method for producing the belt having the configuration of the present invention will be described.

First, a method for producing the base layer 11 will be described. A method for producing a base layer using a coating solution containing at least a resin component, that is, a coating solution containing the polyimide resin precursor or the polyamideimide resin precursor will be described.
The substrate made of polyimide resin or polyamideimide resin is coated on the surface of the cylindrical support (mold) with the precursor liquid by spiral coating with a nozzle or dispenser, or die coating with a wide die, or roll coating using a coating roll. It can be applied by, for example. Here, roll coating will be described. Coating can be performed by an apparatus as shown in FIG. A is a paint pan for storing the defoamed precursor liquid which is a paint, C is an application roller for continuously pumping up the paint B from the paint pan A, and D is a paint pump which is continuously pumped up. A regulating roller for adjusting the thickness with a gap between the coating roller C and a predetermined coating thickness, and E is a cylindrical support for transferring a coating (coating film) having a predetermined thickness from the coating roller C and attaching it. It is a body (mold).

  First, the precursor paint B, which has been sufficiently defoamed in advance, is poured into the paint pan A into the manufacturing apparatus described above. The viscosity of the paint is desirably adjusted to 0.5 to 10 Pa · s with an organic polar solvent (a well-known and conventional one can be used). Next, the paint pan A in which the paint B is poured into the lower part of the application roller C is approached and immersed in the paint B, and the paint B is attached to the surface of the application roller C at a slow peripheral speed of 10 to 100 mm / sec and pumped upward. To go. Thereafter, the thickness of the paint on the application roller C is adjusted by a regulating roller C which is installed on the upper side of the application roller C and can adjust an arbitrary gap with the application roller C. The thickness of the paint to be regulated is preferably about twice the thickness of the paint transferred to the cylindrical support E.

  Next, while the cylindrical support E is slowly rotated on the application roller C, it is brought close to the coating thickness of the application roller C or less. The paint on the application roller is transferred onto the cylindrical support E rotating in the same direction as the application roller C (the “clockwise direction” in the direction shown in FIG. 5), and the cylindrical support is transferred. A paint having a predetermined film thickness is deposited on E.

  After application, 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 support E. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (such as a volatilized solvent). When a self-supporting film is formed, the mold is transferred to a heating furnace (firing furnace) capable of high-temperature processing, and the temperature is raised stepwise, and finally high-temperature heat processing (firing is performed at about 250 ° C. to 450 ° C. And sufficiently imidizing the polyimide resin precursor or polyamide-imide resin precursor.

  After sufficiently cooling, the elastic body is subsequently laminated. The elastic layer can be produced by applying and forming on the base layer 11 using a rubber paint in which rubber is dissolved in an organic solvent, and then drying and crosslinking the solvent. As the coating molding method, as with the base layer 11, existing coating methods such as spiral coating, die coating, and roll coating can be applied. However, in order to improve uneven transferability, the thickness of the elastic body should be increased. As a coating method for forming a thick film, die coating and spiral coating are excellent. Here, the spiral coating will be described. While rotating the base layer in the circumferential direction and continuously supplying rubber paint with a round or wide nozzle, the nozzle is moved in the axial direction of the base layer 11 and the paint is spirally applied on the base layer 11 To do. The paint applied spirally on the base layer 11 is dried while being leveled by maintaining a predetermined rotation speed and drying temperature.

  Then, when sufficiently leveled, as shown in FIG. 6, the powder supply device 25 and the pressing member 23 are installed, and the spherical particles (resin particles) 24 are uniformly applied to the surface from the powder supply device 25 while rotating. The spherical particles 24 coated on the surface are pressed by the pressing member 23 at a constant pressure. The pressing member 23 removes excess spherical particles 24 while embedding the spherical particles 24 in a belt 22 formed by applying a base layer supported by the mold drum 21 and an elastic body. In the present invention, two or more kinds of particles having different triboelectric charging series are used, but those mixed in advance at a desired ratio are supplied to the powder supply apparatus.

  The adjustment of the burying rate of the particles 13 in the elastic layer 12 can be performed by other methods, but can be easily achieved by, for example, adjusting the pressing force of the pressing member 33. For example, although it depends on the viscosity of the casting coating liquid, the resin content, the amount of solvent used, the resin material, etc., as a guideline, the pressing force is 10 mN at a viscosity of 100 to 100,000 mPa · s of the casting coating liquid. By setting the ratio in the range of / cm to 1000 mN / cm, the above-mentioned 50% <buried ratio <100% can be achieved relatively easily.

  After the fine particles are uniformly arranged on the surface, the elastic layer in which the particles are embedded is formed by heating at a predetermined temperature for a predetermined time while rotating. After sufficiently cooling, the base layer is detached from the mold to obtain a desired seamless belt (intermediate transfer belt).

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

  Further, the method for measuring the projected area ratio of the exposed part of the particles on the intermediate transfer belt is not particularly limited and can be appropriately selected according to the purpose. For example, the surface of the intermediate transfer belt is observed with a scanning electron microscope (SEM), and the image is binarized using image processing software (Image-plus; cyber-netics) to expose the exposed portion of the elastic body and the particles. And a method of calculating the projected area ratio of the exposed portion.

  Furthermore, there is no restriction | limiting in particular as a method of measuring the projection area ratio of the particle classification in the said intermediate transfer belt, According to the objective, it can select suitably. For example, the surface of the intermediate transfer member is discriminated by elemental analysis by using an energy dispersive X-ray analyzer (EDX) attached to a scanning electron microscope (SEM), and the projected area of the target particle type in the observation range. The rate can be calculated. In order to increase the measurement accuracy, it is desirable that at least 100 particles are present in the observation range.

  The resistance of the intermediate transfer belt thus manufactured 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 particles and the occupied area ratio. The resistance can be measured by using a commercially available measuring instrument, for example, by using Hiresta manufactured by Dia Instruments.

(Image forming device)
For example, the seamless belt manufactured by the above-described method performs primary transfer by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt, and the primary transfer image is transferred. An electrophotographic apparatus (image forming apparatus) that can be suitably used as an intermediate transfer belt of an electrophotographic apparatus of a so-called intermediate transfer type that performs secondary transfer collectively onto a medium (recording medium) and forms a high-quality image. it can.

  A seamless belt used in a belt constituting unit provided in an electrophotographic apparatus (hereinafter referred to as “image forming apparatus”) in the present invention will be described in detail below with reference to a schematic diagram of a main part. The schematic diagram is an example, and the present invention is not limited to this.

FIG. 7 is a schematic view of a main part for explaining an image forming apparatus equipped with the intermediate transfer belt according to the present invention.
An intermediate transfer unit 500 shown in FIG. 7 includes an intermediate transfer belt 501 that is an intermediate transfer member stretched around a plurality of rollers. Around the intermediate transfer belt 501, a secondary transfer bias roller 605 that is a secondary transfer charge applying unit of the secondary transfer unit 600, a belt cleaning unit 504 that is an intermediate transfer member cleaning unit, and a lubricant of a lubricant application unit. A lubricant application brush 505 or the like that is an application member is disposed so as to face each other.

  A position detection mark (not shown) is provided on the outer peripheral surface or the inner peripheral surface of the intermediate transfer belt 501. However, it is necessary to devise a position detection mark on the outer peripheral surface side of the intermediate transfer belt 501 so as to avoid the passing area of the belt cleaning unit 504, which may be difficult to arrange. 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.

  Further, a neutralizing roller 70 is provided on the inner peripheral surface of the intermediate transfer belt 501 to remove the accumulated charges, and an earth roller 80 is provided and grounded.

  The intermediate transfer belt 501 includes 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, which are primary transfer charge applying units. It is stretched around. Each roller is formed 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 according to the number of superimposed toner images by a primary transfer power source 801 controlled at a constant current or voltage. ing.

The intermediate transfer belt 501 is driven in the arrow direction (clockwise direction) by a belt drive roller 508 that is driven to rotate in the arrow direction by a drive motor (not shown).
The intermediate transfer belt 501 as a belt member is usually a semiconductor or an insulator and has a single-layer or multi-layer structure. However, in the present invention, a seamless belt is preferably used, thereby improving durability. Excellent image formation can be realized. Further, the intermediate transfer belt is set to be larger than the maximum sheet passing size in order to superimpose the toner images formed on the photosensitive drum 200.

  A secondary transfer bias roller 605 serving as a secondary transfer unit is attached to and separated from a belt outer peripheral surface of the intermediate transfer belt 501 in a portion stretched around the secondary transfer counter roller 510 by a contact / separation mechanism, which will be described later. It is configured to be able to contact and separate. The secondary transfer bias roller 605 is disposed so as to sandwich the transfer paper P, which is a medium to be transferred (recording medium), between the portion of the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510. In addition, a transfer bias of a predetermined current is applied by a secondary transfer power source 802 controlled by constant current.

  The registration roller 610 feeds the transfer paper P, which is a transfer medium (transfer material), 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. The secondary transfer bias roller 605 is in contact with a cleaning blade 608 as a cleaning unit. The cleaning blade 608 is for removing the adhering matter adhering to the surface of the secondary transfer bias roller 605 for cleaning.

  In the color copying machine having such a configuration, when an image forming cycle is started, the photosensitive drum 200 is rotated counterclockwise as indicated by an arrow by a drive motor (not shown), and on the photosensitive drum 200, Bk ( Black) toner image formation, C (cyan) toner image formation, M (magenta) toner image formation, and Y (yellow) toner image formation are performed. 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, the primary transfer of the Bk toner image, the C toner image, the M toner image, and the Y toner image is performed by the transfer bias by the voltage applied to the primary transfer bias roller 507. Finally, the respective toner images are formed on the intermediate transfer belt 501 in the order of Bk, C, M, and Y.

For example, the Bk toner image formation is performed as follows.
In FIG. 7, a charging charger 203 uniformly charges the surface of the photosensitive drum 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 with laser light is performed based on the Bk color image signal 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 photosensitive drum 200 that is initially uniformly charged, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the developing roller of the Bk developing device 231K comes into contact with this Bk electrostatic latent image, the toner does not adhere to the remaining portion of the photosensitive drum 200, and the charge is not charged. The toner is attracted to the nonexposed portion, that is, the exposed portion, and a Bk toner image similar to the electrostatic latent image is formed.

  The Bk toner image formed on the photosensitive drum 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 photosensitive drum 200. Some untransferred residual toner remaining on the surface of the photoreceptor drum 200 after the primary transfer is cleaned by the photoreceptor cleaning device 201 in preparation for reuse of the photoreceptor drum 200. On the photosensitive drum 200 side, the process proceeds to the C image forming process after the Bk image forming process, and reading of C image data by a color scanner starts at a predetermined timing. By writing laser light with the C image data, the photosensitive drum A C electrostatic latent image is formed on the surface of 200.

  Then, after the rear end portion of the previous Bk 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 C developing machine 231C develops. The C electrostatic latent image is developed with C toner. Thereafter, the development of the C electrostatic latent image area is continued. When the rear end of the C electrostatic latent image passes, the revolver developing unit is rotated in the same manner as in the case of the previous Bk developing machine 231K. The M developing machine 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. Note that the M and Y image forming steps are the same as the Bk and C steps described above because the operations of reading color image data, forming an electrostatic latent image, and developing are the same as those described above.

  At this time, the potential on the photosensitive drum 200 after exposure by the laser beam L is measured by the potential sensor 204, and the toner density on the photosensitive drum 200 after development by the developing machine 231 is measured by the image density sensor 205. The measurement result is fed back.

  The Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 200 in this manner are sequentially aligned on the same surface on the intermediate transfer belt 501 and primarily transferred. As a result, a toner image (toner image 513) in which four colors at the maximum are 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 reaches the secondary transfer portion where the nip is formed by the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and the secondary transfer bias roller 605. Then, 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, and the transfer paper P is conveyed along the transfer paper guide plate 601, and the transfer paper P and the toner image are transferred. Resist alignment 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, the transfer paper P is discharged. Then, the toner is fed toward the fixing device 270 by the belt conveyance device 210 which is a belt component. 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 drum 200 after the belt transfer is cleaned by the photosensitive member cleaning device 201 and is uniformly discharged by the discharging lamp 202. The 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 charged by the charging charger 503 and then 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 that is in contact with and away from the outer peripheral surface of the intermediate transfer belt 501 is provided. The toner seal member 502 receives the falling toner that has fallen from the belt cleaning blade 504 when cleaning the residual toner, and prevents the falling toner from being scattered 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 color scanner and the image formation on the photosensitive drum 200 are performed at a predetermined timing following the first color (Y) image formation process of the first sheet and the first color of the second sheet. The process proceeds to the image forming process (Bk). Further, the intermediate transfer belt 501 has a second Bk toner in the 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. The image is first 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 case of the single color copy mode, only the predetermined color developing machine 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 photosensitive drum 200 has been described. However, the present invention includes a plurality of photosensitive drums as shown in an exemplary configuration in a schematic diagram of a main part in FIG. The present invention can also be applied to an image forming apparatus arranged side by side along one intermediate transfer belt formed of a seamless belt.

  FIG. 8 shows a configuration of a four-drum digital color printer including four photosensitive drums 21BK, 21Y, 21M, and 21C for forming toner images of four different colors (black, yellow, magenta, and cyan). An example is shown.

  In FIG. 8, the printer main body 10 includes an image writing unit 12, an image forming unit 13, and a paper feeding unit 14 for performing color image formation by electrophotography. Based on the image signal, the image processing unit converts the image into black (BK), magenta (M), yellow (Y), and cyan (C) color signals for image formation and transmits them to the image writing unit 12. To do. The image writing unit 12 is a laser scanning optical system including, for example, a laser light source, a deflector such as a rotary polygon mirror, a scanning imaging optical system, and a mirror group. Image writing corresponding to each color signal is performed on image carriers (photoconductors) 21BK, 21M, 21Y, and 21C that have a writing optical path and are provided for each color of the image forming unit 13.

  The image forming unit 13 includes photoconductors 21BK, 21M, 21Y, and 21C that are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). As each photoconductor for each color, an OPC photoconductor (organic photoconductor) is usually used. Around the photoreceptors 21BK, 21M, 21Y, and 21C, there are a charging device, an exposure unit for laser light from the writing unit 12, and developing devices 20BK, 20M, 20Y for black, magenta, yellow, and cyan, respectively. 20C, primary transfer bias rollers 23BK, 23M, 23Y, and 23C as primary transfer means, a cleaning device (not shown), and a photosensitive member static elimination device (not shown) are arranged. The developing devices 20BK, 20M, 20Y, and 20C use a two-component magnetic brush developing system. The intermediate transfer belt 22, which is a belt component, is interposed between the photosensitive members 21BK, 21M, 21Y, and 21C and the primary transfer bias rollers 23BK, 23M, 23Y, and 23C, and is driven by a driving roller 26 and other rollers. It is stretched and driven in the clockwise direction by the driving roller 26, and the toner images of the respective colors formed on the respective photoconductors are sequentially superimposed and transferred.

  On the other hand, the transfer paper P is fed from the paper feed unit 14 and then carried by the transfer conveyance belt 50, which is a belt component, via the registration roller 16. When the intermediate transfer belt 22 and the transfer conveyance belt 50 come into contact, the toner image transferred onto the intermediate transfer belt 22 is subjected to secondary transfer (collective transfer) by a secondary transfer bias roller 60 as a secondary transfer unit. ) As a result, a color image is formed on the transfer paper P. The transfer paper P on which the color image is formed is conveyed to the fixing device 15 by the transfer conveying belt 50, and after the image transferred by the fixing device 15 is fixed, it is discharged out of the printer main body.

  The residual toner that is not transferred during the secondary transfer and remains on the intermediate transfer belt 22 is removed from the intermediate transfer belt 22 by the belt cleaning member 25. A lubricant application device 27 is disposed on the downstream side of the belt cleaning member 25. The lubricant application device 27 includes a solid lubricant and a conductive brush that rubs the intermediate transfer belt 22 to apply the solid lubricant. The conductive brush is always in contact with the intermediate transfer belt 22 and applies a solid lubricant to the intermediate transfer belt 22. The solid lubricant has an effect of improving the cleaning property of the intermediate transfer belt 22, preventing the occurrence of filming, and improving the durability.

  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. Is also within the scope of the present invention.

[Example 1]
A base layer coating solution was prepared as follows, and a seamless belt base layer was produced using this coating solution.

<Preparation of base layer coating solution>
First, carbon black (Special Black 4; Evonik Degussa Co., Ltd.) dispersed in N-methyl-2-pyrrolidone with a bead mill in advance in a polyimide varnish (U-Varnish A; manufactured by Ube Industries) containing a polyimide resin precursor as a main component. (Manufactured) was prepared so that the carbon black content was 17% by weight of the polyamic acid solid content, and well stirred and mixed to prepare a coating solution.

<Manufacture of seamless belts>
Next, a metal cylindrical support whose outer surface having an outer diameter of 340 mm and a length of 360 mm was roughened by blasting was used as a mold and attached to a roll coater. Next, the coating liquid A for base layer was poured into the pan, the paint was pumped up at a rotation speed of the application roller of 40 mm / sec, and the thickness of the paint on the application roller was controlled by setting the gap between the regulation roller and the application roller to 0.6 mm. The rotational speed of the cylindrical support was controlled to 35 mm / sec, approaching the coating roller, and the coating on the coating roller was uniformly transferred onto the cylindrical support with a gap of 0.4 mm from the coating roller. Then, while maintaining the rotation, it was put into a hot air circulating dryer, gradually heated to 110 ° C. and heated for 30 minutes, further heated to 200 ° C. for 30 minutes, and the rotation was stopped. Thereafter, this was introduced into a heating furnace (baking furnace) capable of high-temperature treatment, heated up to 320 ° C. stepwise, and heat-treated (baked) for 60 minutes to form a base layer having a thickness of 80 μm.

<Production of elastic layer on base layer>
The respective constituent materials shown below were mixed and sufficiently kneaded using a biaxial kneader to prepare a rubber composition.

<Elastic layer material>
・ Acrylic rubber Nipol AR12 (Nippon ZEON Co., Ltd.) 100 parts by weight ・ Stearic acid Bead stearic acid Tsubaki (NOF Corporation) 1 part by weight ・ Red phosphorus Nova Excel 140F (Rin Chemical Industry Co., Ltd.) 10 parts by weight ・ Aluminum hydroxide Heidilite H42M (Showa Denko KK) 50 parts by weight / crosslinking agent Diak. No1 (hexamethylenediamine carbamate)
(DuPont Dow Elastomer Japan) 0.6 parts by weight / crosslinking accelerator VULCOFAC ACT55
(Salt of 70% 1,8-diazabicyclo (5,4,0) undecene-7 and dibasic acid, 30% amorphous silica) (Safic alca)
1 part by weight, conductive agent QAP-01 (tetrabutylammonium perchlorate)
(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 support on which the prepared polyimide base layer was formed, the prepared rubber solution was moved to the support axis method while continuously discharging rubber paint from the nozzle onto the polyimide base layer. Coated. The coating amount was such that the final film thickness was 600 μm.

  Next, by using the method of FIG. 6, silicone resin particles (Tospearl 120 (volume average particle diameter 2.0 μm); Momentive Performance Materials) 80 wt% and acrylic resin particles (Techpolymer SSX-102) are used as spherical particles. (Volume average particle diameter 2.0 μm); Sekisui Plastics Co., Ltd.) Mix the mixed particle powder thoroughly mixed with 20 wt% onto the surface evenly, and press the pressing member of the polyurethane rubber blade to fix it to the elastic layer did. At this time, the pressing force of the pressing member was set to 100 mN / cm.

  After finishing the entire surface of the belt, the cylindrical support coated with the rubber paint is put into a hot air circulating dryer while rotating as it is, and the temperature is raised to 170 ° C. at a temperature rising rate of 4 ° C./min. Heat treatment was performed for 60 minutes. After stopping the heating, it was gradually cooled to room temperature and then removed from the mold to prepare an intermediate transfer belt A.

[Example 2]
The spherical particles in Example 1 were mixed with silicone resin particles (Tospearl 120 (volume average particle size 2.0 μm); Momentive Performance Materials) 80 wt% and melamine resin particles (Optobead 2000M (volume average particle size 2.0 μm). ); Nissan Chemical Industries, Ltd.) An intermediate transfer belt B was obtained in the same manner except that the mixed particle powder was sufficiently mixed with 20 wt%.

[Example 3]
The spherical particles in Example 1 were mixed with silicone resin particles (Tospearl 2000B (volume average particle diameter 6.0 μm); Momentive Performance Materials) 80 wt% and polystyrene resin particles (Techpolymer SBX-6 (volume average particle diameter 6). 0.0 μm); manufactured by Sekisui Plastics Co., Ltd.) An intermediate transfer belt C was obtained in the same manner except that the mixed particle powder was sufficiently mixed with 20 wt%.

[Example 4]
The spherical particles in Example 1 were mixed with 40 wt% silicone resin particles (Tospearl 120 (volume average particle size 2.0 μm); Momentive Performance Materials) and acrylic resin particles (Techpolymer SSX-102 (volume average particle size 2). 0.0 μm); manufactured by Sekisui Plastics Co., Ltd.), except that the mixed particle powder was sufficiently mixed, and an intermediate transfer belt D was obtained.

[Example 5]
The spherical particles in Example 1 were mixed with silicone resin particles (Tospearl 120 (volume average particle diameter 2.0 μm); Momentive Performance Materials) 98 wt% and acrylic resin particles (Techpolymer SSX-102 (volume average particle diameter 2). 0.0 μm); manufactured by Sekisui Plastics Co., Ltd.), except that the mixed particle powder was sufficiently mixed, and an intermediate transfer belt E was obtained.

[Comparative Example 1]
In Example 1, the spherical transfer particles are replaced with silicone resin particles (KMP-701 (volume average particle diameter: 3.5 μm); Shin-Etsu Silicone), and the second particles are the same except that the intermediate transfer belt F is manufactured. did.

[Comparative Example 2]
In Example 1, the spherical particles are replaced with acrylic resin particles (Techpolymer SSX-102 (volume average particle diameter 2.0 μm); manufactured by Sekisui Plastics Co., Ltd.), and the second particles are the same except that they are not used. An intermediate transfer belt G was prepared.

The intermediate transfer belts A to G of the above examples and comparative examples were mounted on the electrophotographic apparatus of FIG. 8, and the following various evaluations were performed.
<Measurement of transfer rate>
As the transfer paper, paper having a concavo-convex pattern on the surface (continuous weight 260 kg paper, resack paper) was used. The operation to output a solid blue image was performed, and 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 transfer rate Was calculated.

<Measurement of transfer rate at the time of continuous image output of 200,000 sheets>
After continuous output of 10,000 test chart images, the test chart was stopped and the transfer rate was measured according to the above method.

<Image evaluation at the time of continuous image output of 200,000 sheets>
After continuous output of 10,000 test chart images, a full-tone cyan halftone image was output on 260 kg paper lazac paper, and an abnormal image was observed.

  The results are shown in Table 1 below.

  In Examples 1 to 5, excellent image quality was obtained at the initial stage and after output of 200,000 sheets, and excellent performance was exhibited.

  On the other hand, in Comparative Examples 1 and 2 using a single particle, transfer performance as excellent as that of the example of the present invention could not be obtained. In Comparative Example 1 using only silicone particles with strong negative chargeability, an abnormal image with uneven density was confirmed when a halftone image was output.

  As described above, with the configuration of the present invention, an intermediate transfer belt for realizing a high durability and high image quality electrophotographic apparatus that can achieve a high transfer rate irrespective of a transfer medium and can be sustained for a long time is obtained. Can be realized.

(Reference in FIG. 1)
11 Base layer 12 Elastic layer 13 Spherical particle (reference numeral in FIG. 2)
12 Elastic layer 13 Spherical particle (reference numeral in FIG. 3)
12 Elastic layer 14 First particle 15 Second particle (reference numeral in FIG. 4)
12 Elastic layer 13 Spherical particle (reference numeral in FIG. 5)
A Paint pan B Paint C Coating roll D Regulating roll E Cylindrical support (mold)
(Reference in FIG. 6)
21 Die drum 22 Belt 23 coated with base layer and elastic layer Pressing member 24 Resin particle 25 Powder coating device (reference numeral in FIG. 7)
P Transfer paper L Laser light 70 Static elimination roller 80 Ground roller 200 Photosensitive drum 201 Photosensitive drum cleaning device 202 Static elimination lamp 203 Charging charger 204 Potential sensor 205 Image density sensor 210 Belt conveying device 230 Revolver developing unit 231Y Y developing machine 231K Bk developing machine 231C C developing machine 231M M developing machine 270 fixing device 271 272 fixing roller 500 intermediate transfer unit 501 intermediate transfer belt 502 toner seal member 503 charging charger 504 belt cleaning unit 505 lubricant application brush 506 lubricant 507 primary transfer bias roller 508 Belt drive roller 509 Belt tension roller 510 Secondary transfer counter roller 511 Cleaning counter roller 512 Feedback current detection sensor 513 Toner image 514 Optical sensor 600 Secondary transfer unit 601 Transfer paper guide plate 605 Secondary transfer bias roller 606 Transfer paper neutralization charger 608 Cleaning blade 610 Registration roller 801 Primary transfer power source 802 Secondary transfer power source (reference numeral in FIG. 8) )
P Transfer paper 10 Printer body 12 Image writing unit 13 Image forming unit 14 Paper feeding unit 15 Fixing device 16 Registration roller 20BK, 20M, 20Y, 20C Developing device 21BK, 21M, 21Y, 21C Photoconductor 22 Intermediate transfer belt 23BK, 23M , 23Y, 23C Primary transfer bias roller 25 Belt cleaning member 26 Drive roller 27 Lubricant coating device 50 Transfer conveyor belt 60 Secondary transfer bias roller

JP-A-9-230717 JP 2002-162767 A JP 2004-354716 A JP 2007-328165 A JP 2009-75154 A JP 2011-150059 A

Claims (8)

An intermediate transfer belt to which a toner image obtained by developing a latent image formed on an image carrier with toner is transferred,
A base layer, and an elastic layer laminated on the base layer,
The elastic layer contains an elastic body and spherical particles, and an uneven shape is formed on the surface.
The spherical particles consist of two or more different triboelectric series,
An intermediate transfer belt, wherein a difference in volume average particle size between a particle type having the largest volume average particle size and a particle type having the smallest volume average particle size in the spherical particles is less than 1.0 μm.   The intermediate transfer belt according to claim 1, wherein the difference in volume average particle diameter is within 0.5 μm.   3. The intermediate transfer belt according to claim 1, wherein one of two or more spherical particles of the spherical particles is a silicone resin particle. 4.   The intermediate transfer belt according to claim 3, wherein the projected area ratio of the silicone resin particles is in a range of 60% to 95% with respect to the entire projected area ratio of the spherical particles.   The intermediate transfer belt according to claim 3 or 4, wherein the spherical particles include spherical particles made of a material that is more easily positively charged by frictional charging than the silicone resin particles.   6. The intermediate transfer belt according to claim 5, wherein the spherical particles made of a material easily positively charged according to claim 5 are acrylic resin particles.   An image forming apparatus comprising the intermediate transfer belt according to claim 1. A manufacturing method for manufacturing the intermediate transfer belt according to any one of claims 1 to 6,
Forming the base layer;
Forming the elastic body;
Applying the spherical particles uniformly on the elastic body by drying;
And a step of uniformly forming the spherical particles by arranging and embedding the spherical particles.