JP2012177761A - Intermediate transfer belt, method for manufacturing the same, and image forming apparatus using the intermediate transfer belt - Google Patents

Abstract

The present invention provides an intermediate transfer belt in which particles do not fall out even when bent or the like, has excellent durability, and can maintain an initial state of toner releasability.
At least an elastic layer, spherical particles are attached or buried on the elastic layer to form a particle layer, and the spherical particles with respect to the sum of the projected area of the exposed portion of the elastic layer and the projected area of the spherical particles In an intermediate transfer belt for an electrophotographic apparatus having a projected area (hereinafter referred to as initial particle partial occupancy) of 60% or more, and an MIT test machine that applies a load of 9.8 N to the belt. When bent 10 times with a bending radius R = 0.38 and a bending angle a = 135 °, the particle detachment from the particle layer has a particle partial occupancy of (initial particle partial occupancy−10)% or more. It is characterized by being in such a range.
[Selection] Figure 2

Description

  The present invention is a seamless belt-shaped intermediate transfer belt equipped in an image forming apparatus such as a copy printer, a method for manufacturing the intermediate transfer belt, and an image forming apparatus using the intermediate transfer belt, particularly suitable for full-color image formation. The present invention relates to an intermediate transfer belt, a method for manufacturing the intermediate transfer belt, and an image forming apparatus using the intermediate transfer belt.

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

  Such an intermediate transfer belt system has been used in a system that uses four color developing devices for one image carrier (photosensitive member), 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.
Incidentally, the intermediate transfer belt has a primary transfer function for receiving toner from the image carrier and a secondary transfer function for transferring toner to the recording medium. However, both the primary transfer and the secondary transfer are required to improve the transfer rate. Particularly in secondary transfer, if the transfer rate is low, the toner that could not be transferred onto the recording medium remains on the intermediate transfer belt, which is liable to cause image defects and filming. In recent years, the demand for printing not only on plain paper but also on uneven paper has increased, and the development of intermediate transfer belts that can support uneven paper is also becoming increasingly common.
In general, printing on uneven paper tends to have a lower secondary transfer rate than plain paper. The cause is that the intermediate transfer belt does not adhere to the concave portion of the uneven paper, so that the toner cannot be completely transferred to the paper. It will be left on top.

Similar to the plain paper compatible intermediate transfer belt, even in the intermediate transfer belt corresponding to the concavo-convex paper, if toner adheres to the belt, filming occurs and the image is deteriorated.
In order to solve this problem, development of an intermediate transfer belt having a multilayer structure and an elastic layer in the layer and having good followability to uneven paper has been actively conducted.
Since it is important that the single layer belt has high bending strength and tear strength, polyimide or polyphenylene sulfide is used. Such materials also have high gloss, high hardness and low surface tack.
On the other hand, in the multilayer elastic belt, a material having a high strength similar to the above is used for the base material layer, and the elastic layer is laminated thereon. In general, rubber-based materials are often used for the elastic layer, and the elastic layer has good followability to paper. However, if the surface in contact with the toner is untreated, the surface is tacky, and the toner is released. There is a problem that the secondary transfer rate is lowered due to poor properties.

  In order to solve this problem, there is a method of newly providing a protective layer. However, when a material with sufficiently high transfer performance is coated, the flexibility of the flexible layer cannot be followed and cracking or peeling will occur. It is not preferable. On the other hand, proposals have been made to improve transferability by attaching fine particles to the surface.

That is, Patent Document 1 proposes coating the elastic layer with beads having a diameter of 3 μm or less. However, the technique described in this publication causes particle detachment, which is not sufficient with respect to the durability required of recent electrophotographic apparatuses.
Patent Document 2 proposes that a thermoplastic resin, an elastomer, or carbon black is melt-kneaded and a resin layer is formed by extrusion molding, and then the resin is melted again by hot pressing to bury silica. However, it is difficult to control the adhesion state of silica with the technique described in this publication.
Patent Document 3 proposes a configuration that realizes durability by embedding silica particles in an adhesive layer. However, in the technique described in this publication, it is difficult for the particles to exist in a single layer because a coating in which silica particles are dispersed in methyl ethyl ketone (MEK) is applied on the outer peripheral surface of the belt body by spray coating. As a result, non-uniformity occurs in the existence, and it is impossible to obtain a product that satisfies the high level of image quality required of recent electrophotographic apparatuses.

In all of Patent Documents 1 to 3, 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
In addition, the intermediate transfer belt is used in a state where tension is applied on the transfer roll, friction with the edge of the paper occurs, and stress during use is applied, so that sufficient adhesion strength is not applied to the particle layer. If so, the particles are detached during use. Since the detachment of the particles from the particle layer leads to a decrease in the secondary transfer rate of the intermediate transfer belt, it is very important to increase the adhesion strength between the elastic layer and the particles of the particle layer.

The present invention has been made in view of the above-described prior art, is flexible, has excellent toner releasability, can achieve a high transfer rate regardless of the transfer medium, and can be sustained over a long period of time. In order to realize a high-quality electrophotographic apparatus, an object is to obtain an intermediate transfer belt excellent in adhesion strength between the elastic layer and the particles in the particle layer.
Hereinafter, the “electrophotographic apparatus” may be referred to as an “image forming apparatus”.

As a result of intensive studies, the inventors of the present invention have found that when the MIT tester is applied with a load of 9.8 N on the belt and is bent 10 times at a bending radius R = 0.38 and a bending angle a = 135 °, It was found that the intermediate transfer belt can withstand long-term use if the particle separation (difference between the initial particle partial occupancy with respect to the belt surface and the particle partial occupancy after bending) is 10% or less. . Also, before the elastic rubber of the intermediate transfer belt is vulcanized, the elastic layer is coated with independent spherical particles, and after being pressurized or without being pressurized, vulcanization is performed under optimum conditions for bending, etc. In contrast, it has been found that an intermediate transfer belt can be obtained in which particles do not fall out of the particle layer, have good durability, and maintain the initial state of toner releasability.
The initial state of the intermediate transfer belt is that when 60% or more of the sum of the projected area of the exposed portion of the elastic layer and the projected area of the spherical particle is the projected area of the spherical particle (that is, the area of the particle portion is equal to the projected area). It was found that good secondary transferability can be obtained even after the particles are detached (if the area ratio of the elastic rubber portion is 60% or more).
The present invention has been made based on these findings. That is, the said subject of this invention is achieved by the following (1)-(9).

(1) At least an elastic layer, spherical particles are attached or buried on the elastic layer to form a particle layer, and the spherical particles have a sum of the projected area of the exposed portion of the elastic layer and the projected area of the spherical particles. An intermediate transfer belt for an electrophotographic apparatus having a projected area (hereinafter referred to as an initial particle partial occupancy ratio) of 60% or more, which is bent by an MIT test machine that applies a load of 9.8 N to the belt. When bent 10 times at a radius R = 0.38 and a bending angle a = 135 °, the particle detachment from the particle layer seems to have a particle partial occupancy of (initial particle partial occupancy−10)% or more. An intermediate transfer belt characterized by being in a range.
(2) When bent 100 times with a bend radius R = 0.38 and a bend angle a = 135 ° with an MIT test machine applied with a load of 9.8 N, particle detachment from the particle layer is caused by a particle portion. The intermediate transfer belt according to (1) above, wherein the occupation ratio is in a range such that (initial particle partial occupation ratio-20)% or more.
(3) The intermediate transfer belt according to (1) or (2), wherein the elastic layer is made of a thermosetting resin.
(4) The intermediate transfer belt according to any one of the above (1) to (3), wherein an average particle diameter b of the spherical particles is 1 μm <b <6 μm.
(5) The intermediate transfer belt according to any one of (1) to (4), wherein the spherical particles are resin particles.
(6) The intermediate transfer belt according to (5), wherein the resin particles are silicone resin particles.

(7) In the method for producing an intermediate transfer body by sequentially laminating an elastic layer and a particle layer in which independent spherical particles are provided in the surface direction to form an uneven shape on the base material layer, on the base material layer, After the elastic layer forming liquid is applied and heated, spherical particles having an average particle diameter b of 1 μm <b <6 μm are formed on the elastic layer, and the projected area of the exposed portion of the elastic layer and the projected area of the spherical particles are The dry coating is performed so that 60% or more of the sum of the above becomes the projected area of the spherical particles, and a particle layer is formed without pressurization or pressurization, and then the elastic layer is vulcanized by heating for 1 hour or more. A process for producing an intermediate transfer belt characterized by the above.

(8) A latent image forming unit that forms a latent image on an image carrier, a developing unit that develops the latent image with toner to form a toner image, and an intermediate transfer unit that transfers the toner image to an intermediate transfer member In the image forming apparatus comprising: a transfer unit that transfers the toner image transferred to the intermediate transfer member to a recording medium; and a fixing unit that fixes the toner image transferred onto the recording medium. Is an intermediate transfer belt according to any one of the above (1) to (6).
(9) The image forming apparatus as described in (8) above, wherein the image forming apparatus is a full-color image forming apparatus in which a plurality of latent image carriers having developing units for respective colors are arranged in series.

  As will be apparent from the following detailed and specific description, according to the present invention, high transfer performance can be maintained not only for the initial period but also for a long period regardless of the type and surface properties of the transfer medium. In addition, an electrophotographic apparatus having high durability and high image quality can be obtained for a long time without damaging the photoreceptor.

It is a figure for demonstrating operation which makes a spherical resin particle adhere on an elastic layer. It is a principal part schematic diagram for demonstrating the image forming apparatus equipped with the seamless belt obtained by the manufacturing method which concerns on this invention as a belt member. FIG. 3 is a schematic diagram of a main part showing an example of a configuration of an image forming apparatus in which a plurality of photosensitive drums are arranged in parallel along one intermediate transfer belt formed of a seamless belt according to the present invention.

As described above, the seamless belt according to the present invention includes at least an elastic layer, and a particle layer in which spherical particles (monodispersed particles) are attached or buried on the elastic layer to form a concavo-convex shape. This is an intermediate transfer belt for an electrophotographic apparatus in which the projected area of the spherical particles (hereinafter referred to as initial particle portion occupancy) with respect to the sum of the projected area of the exposed portion and the projected area of the spherical particles is 60% or more. Thus, when the belt is bent 10 times with a bending radius R = 0.38 and a bending angle a = 135 ° in the MIT test method performed by applying a load of 9.8 N to the belt, particle detachment from the particle layer is: The particle partial occupancy is in a range such that (initial particle partial occupancy-10)% or more.
The intermediate transfer belt of the present invention will be described below.

  The seamless belt of the present invention comprises an intermediate transfer belt type electrophotographic apparatus [a so-called so-called image carrier (for example, a photosensitive drum) in which a plurality of color toner developed images sequentially formed are sequentially superimposed on the intermediate transfer belt. The apparatus is suitably equipped as an intermediate transfer belt in an apparatus that performs primary transfer and performs secondary transfer of the primary transfer image collectively onto a recording medium].

  As an embodiment for carrying out the present invention, the structure is at least two layers including at least an elastic layer and a surface layer (resin particle layer). Further, it is preferable that a particle layer composed of independent monodispersed particles (spherical particles) is formed thereon.

<Base material layer>
As a constituent material of the base material layer, a material containing a filler (or additive) for adjusting electric resistance in the resin, that is, a so-called electric resistance adjusting material can be mentioned.
As such a resin, from the viewpoint of flame retardancy, for example, a fluorine-based resin such as PVDF, ETFE, a polyimide resin or a polyamide-imide resin is preferable, and particularly from the viewpoint of mechanical strength (high elasticity) and heat resistance. A polyimide resin or a polyamideimide resin is preferred.

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 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.
The electrical resistance adjusting material in the present invention is not limited to the above exemplary compounds.
In addition, the coating liquid containing at least the resin component in the method for producing a seamless belt of the present invention further contains additives such as a dispersion aid, a reinforcing material, a lubricant, a heat conduction material, and an antioxidant as necessary. 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. Although the amount is 10 ¹² Ω · cm, 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.

  A polyimide resin (hereinafter sometimes abbreviated as “polyimide”) or a polyamideimide resin (hereinafter sometimes abbreviated as “polyamideimide”) suitably used as a material for the seamless belt is specifically described below. explain.

<Polyimide>
Although it does not limit as a polyimide used for this invention, Aromatic polyimide is mentioned as a preferable example. The aromatic polyimide is obtained via a polyamic acid (polyimide precursor) by a reaction between a generally known aromatic polycarboxylic acid anhydride (or a derivative thereof) and an aromatic diamine.
That is, polyimide, particularly aromatic polyimide, is insoluble in solvents and the like due to its rigid main chain structure and has an infusible property. Therefore, first, a polyimide precursor (polyamic acid or polyamic acid) soluble in an organic solvent is synthesized by a reaction between an aromatic polycarboxylic acid anhydride and an aromatic diamine. Molding is performed by the method, and then the polyamic acid is heated or dehydrated by a chemical method to be cyclized (imidized) to obtain polyimide. The outline of the reaction for obtaining the aromatic polyimide is shown in the following formula (1).

[In formula (1), Ar ¹ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and Ar ² represents a divalent aromatic residue containing at least one carbon 6-membered ring. . ]

Specific examples of the tetravalent aromatic carboxylic acid anhydride (aromatic polyvalent carboxylic acid anhydride) containing at least one carbon 6-membered ring include, for example, pyromellitic dianhydride, 3, 3 ′, 4 , 4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2, 2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-Zika Boxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxylphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic Acid dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid An anhydride etc. are mentioned. You may use these individually or in mixture of 2 or more types.
In addition, an acid anhydride other than the aromatic polyvalent carboxylic acid anhydride represented by the above formula (1), for example, an aliphatic polyvalent carboxylic acid such as ethylenetetracarboxylic dianhydride or cyclopentanetetracarboxylic dianhydride. Acid anhydrides can also be used, and these may be used alone or in combination with the aromatic polycarboxylic acid anhydride.
In the formula (1), an aromatic polyvalent carboxylic acid anhydride is used, but a derivative thereof (for example, an ester derivative) may be used.

Next, specific examples of the divalent aromatic diamine (aromatic diamine) containing at least one carbon 6-membered ring to be reacted with the aromatic polyvalent carboxylic acid anhydride include, for example, m-phenylenediamine, o- Phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis (3-aminophenyl) ) Sulfide, (3-aminophenyl) (4-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone, (3-aminophenyl) ( -Aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4 '-Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- ( 3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] -ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2- Bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] Lopan, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [3- (3-amino Phenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3- Hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone Bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-amino Phenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [ 4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [ 4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [3- (4-aminophenoxy) Benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4, 4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4 -(4-aminophenoxy) phenoxy] -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, and the like. You may use these individually or in mixture of 2 or more types. In order to effectively express the physical properties in the present invention, it is particularly preferable to use 4,4′-diaminodiphenyl ether as at least one of the components.
In addition, aliphatic diamines other than the aromatic diamine represented by the above formula (1) can also be used and may be used in combination with the aromatic diamine.

  In the case of obtaining an aromatic polyimide, a polyimide precursor (polyamic acid) is obtained by polymerization reaction in an organic polar solvent using substantially equal moles of the aromatic polycarboxylic acid anhydride component and the aromatic diamine component. Then, the polyamic acid is dehydrated to cyclize and imidize. Below, the manufacturing method of a polyamic acid is demonstrated concretely.

Here, examples of the organic polar solvent used in the polymerization reaction for obtaining the polyamic acid include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, and formamide such as N, N-dimethylformamide and N, N-diethylformamide. Solvents, acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m- Or phenol solvents such as p-cresol, xylenol, halogenated phenol, catechol, ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcohol solvents such as methanol, ethanol, butanol, cellosolve such as butyl cellosolve Or hexamethylphosphoramide, etc. can be mentioned γ- butyrolactone, to use them alone or as a mixed solvent desirable.
The solvent is not particularly limited as long as it dissolves the polyamic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

  As an example of producing a polyimide precursor, first, one or more kinds of diamines are dissolved in the above organic solvent or dispersed in a slurry state in an inert gas atmosphere such as argon or nitrogen. When at least one aromatic polycarboxylic acid anhydride (or derivative thereof) is added to this solution (either in a solid state, in a solution state dissolved in an organic solvent, or in a slurry state), heat is generated. Thus, a ring-opening polyaddition reaction occurs, and the viscosity of the solution rapidly increases, and a high molecular weight polyamic acid solution is obtained. In this case, the reaction temperature is usually controlled to −20 ° C. to 100 ° C., desirably 60 ° C. or less. The reaction time is about 30 minutes to 12 hours.

  The above is an example. Contrary to the addition procedure in the reaction, first, an aromatic polyvalent carboxylic acid anhydride (aromatic tetracarboxylic dianhydride) or a derivative thereof is dissolved or dispersed in an organic solvent, The aromatic diamine (substantially, “diamine”) may be added to the solution. The diamine may be added in a solid state, in a solution state dissolved in an organic solvent, or in a slurry state. That is, the mixing order of the aromatic tetracarboxylic dianhydride component and the diamine component is not limited. Further, the aromatic tetracarboxylic dianhydride and the diamine may be simultaneously added to the organic polar solvent for reaction.

  As described above, the polyamic acid is uniformly mixed in the organic polar solvent by polymerizing the aromatic polyvalent carboxylic acid anhydride or derivative thereof and the aromatic diamine component in about an equimolar amount in the organic polar solvent. A polyimide precursor solution is obtained in a dissolved state.

The polyimide precursor solution in the present invention (polyamic acid solution: “coating solution containing a polyimide resin precursor”) can be synthesized as described above, but it can be easily used as an organic solvent. What is marketed as what is called a polyimide varnish of the state in which the polyamic acid composition was dissolved can also be obtained and used.
Examples of this include Trenys (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries, Ltd.), Rika Coat (manufactured by Nippon Nippon Chemical Co., Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 ( Sumitomo Bakelite Co., Ltd.) is a typical example.

  Mix and disperse fillers (for example, electrical resistance adjusting agents, or additives such as dispersion aids, reinforcing materials, lubricants, heat conduction materials, antioxidants, etc.) into the synthesized or obtained polyamic acid solution as necessary. Thus, a coating solution is prepared. The coating liquid is applied to a support (molding mold) as described later, and then subjected to a treatment such as heating, whereby conversion (imidation) from polyamic acid, which is a polyimide precursor, to polyimide is performed.

The polyamic acid can be imidized by the heating method (1) or the chemical method (2) as described above.
The heating method (1) is a method of converting polyamic acid to polyimide by, for example, heat treatment at 200 to 350 ° C., and is a simple and practical method for obtaining polyimide (polyimide resin).
On the other hand, the chemical method (2) is a method in which a polyamic acid is reacted with a dehydrating cyclization reagent (for example, a mixture of a carboxylic acid anhydride and a tertiary amine, etc.) and then heated to completely imidize, Compared with the heating method of (1), since it is a complicated and expensive method, the method of (1) is usually used frequently.
In order to exhibit the intrinsic performance of polyimide, it is preferable to complete imidization by heating to a temperature above the glass transition temperature of the corresponding polyimide.

The progress of imidization (degree of imidization) can be evaluated by a usual method for measuring the imidization rate.
As a method for measuring such an imidization rate, for example, a nucleus calculated from an integral ratio of ¹ H attributed to an amide group in the vicinity of 9 to 11 ppm and ¹ H attributed to an aromatic ring in the vicinity of 6 to 9 ppm. Various methods such as magnetic resonance spectroscopy (NMR method), Fourier transform infrared spectroscopy (FT-IR method), a method for quantifying moisture accompanying imide ring closure, and a carboxylic acid neutralization titration method are used. Fourier transform infrared spectroscopy (FT-IR method) is the most common method.

In the Fourier transform infrared spectroscopy (FT-IR method), the imidization rate is defined as, for example, the following formula (i).
That is, assuming that (A) is the number of moles of imide groups at the firing stage (imidation treatment stage) and (B) is the number of moles of imide groups when 100% imidized (theoretical), Is done.
Imidation ratio (%) = [(A) / (B)] × 100 (i)

  The number of moles of the imide group in this definition can be determined from the absorbance ratio of the characteristic absorption of the imide group measured by the FT-IR method. For example, as a typical characteristic absorption, the imidization ratio can be evaluated using the following absorbance ratio.

(1) Absorbance ratio between 725 cm ⁻¹ (immobilization vibration band of imide ring C═O group), which is one of characteristic absorptions of imide, and 1,015 cm ⁻¹ of characteristic absorption of benzene ring (2) Characteristics of imide Absorbance ratio between 1,380 cm ⁻¹ (inflection band of imide ring C—N group) which is one of absorption and characteristic absorption 1,500 cm ^{−1 of} benzene ring (3) One of characteristic absorption of imide Absorbance ratio between 1,720 cm ⁻¹ (an oscillating band of imide ring C═O group) and 1,500 cm ⁻¹ characteristic absorption of benzene ring (4) 1, which is one of characteristic absorption of imide Absorbance ratio between 720 cm ⁻¹ and amide group characteristic absorption 1,670 cm ⁻¹ (interaction between amide group N—H bending vibration and CN stretching vibration) and amide group over 3000 to 3300 cm ⁻¹ Confirm that the multiple absorption bands from the source have disappeared. Further more reliable imidization complete if.

<Polyamideimide>
Next, polyamideimide will be described.
Polyamideimide is a resin having a rigid imide group and an amide group imparting flexibility in the molecular skeleton, and the polyamideimide used in the present invention may have a generally known structure. Although not limited, aromatic polyamide imide is a particularly preferable example.
As a method for synthesizing the polyamideimide resin, the following known acid chloride method (a) or isocyanate method (b) can be applied.
(A) Acid chloride method: derivative of trivalent carboxylic acid compound having acid anhydride group and carbonyl halide group [hereinafter referred to as “derivative halide of trivalent carboxylic acid compound having acid anhydride group”. is there. ] (Most typically, an acid chloride compound of the derivative) and a diamine are reacted in a solvent to produce a polyamideimide via a polyamide-amic acid (polyamideimide resin precursor). For example, a method described in Japanese Patent Publication No. 42-15637 is known.
(B) Isocyanate method: a trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group [hereinafter sometimes referred to as “a derivative of a trivalent carboxylic acid having an acid anhydride group”. ] And an isocyanate compound (in particular, an aromatic isocyanate compound is preferred) in a solvent to produce a polyamideimide. For example, a method described in Japanese Patent Publication No. 44-19274 is known.

  In the present invention, both the acid chloride method (a) and the isocyanate method (b) can be used. Each production method will be described below with an aromatic polyamideimide preferably used as an example.

(A) Acid chloride method:
As a derivative halide of a trivalent carboxylic acid compound having an acid anhydride group, for example, compounds represented by the following structural formula (2) and structural formula (3) can be used.

  [In the formula (2), X represents a halogen atom. ]

[In Formula (3), X represents a halogen atom, and Y represents a single bond, —CH ₂ —, —CO—, —SO ₂ — or —O—. ]

In Structural Formula (2) or Structural Formula (3), examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom, with a chlorine atom being preferred. Most representative is trimellitic anhydride chloride.
A derivative halide of a trivalent carboxylic acid compound having an acid anhydride group represented by the structural formula (2) or the structural formula (3) is an example of a raw material for obtaining an aromatic polyamideimide. It is not something that can be done.
In addition to the aromatic trivalent carboxylic acid compound represented by the structural formula (2) or structural formula (3), a derivative halide of a trivalent carboxylic acid compound having an aliphatic acid anhydride group can also be used. Yes, it can be used in combination with aromatic derivatives.

On the other hand, the diamine to be reacted with the aromatic polyvalent carboxylic acid anhydride in the acid chloride method is not particularly limited, but any of aromatic diamine, aliphatic diamine, and alicyclic diamine can be used, but aromatic diamine is preferred. Used.
Aromatic diamines include m-phenylenediamine, p-phenylenediamine, oxydianiline, diamino-m-xylylene, diamino-p-xylylene, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6- Naphthalenediamine, 2,7-naphthalenediamine, 2,2'-bis- (4-aminophenyl) propane, 2,2'-bis- (4-aminophenyl) hexafluoropropane, 4,4'-diaminodiphenyl Sulfone, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl ether, 3,4-diaminobiphenyl, 4,4′-diaminobenzophenone, 3,4-diaminodiphenyl ether, isopropyl Lidendianiline, 3,3′-Diaminobenzophenone, -Tolidine, 2,4-tolylenediamine, 1,3-bis- (3-aminophenoxy) benzene, 1,4-bis- (4-aminophenoxy) benzene, 1,3-bis- (4-aminophenoxy) ) Benzene, 2,2-bis- [4- (4-aminophenoxy) phenyl] propane, bis- [4- (4-aminophenoxy) phenyl] sulfone, bis- [4- (3-aminophenoxy) phenyl] Sulfone, 4,4′-bis- (4-aminophenoxy) biphenyl, 2,2′-bis- [4- (4-aminophenoxy) phenyl] hexafluoropropane, 4,4′-diaminodiphenyl sulfide, 3 , 3′-diaminodiphenyl sulfide and the like.
Examples of the aliphatic diamine include methylene diamine and hexafluoroisopropylidene diamine.
Also, siloxane compounds having amino groups at both ends as diamines, such as 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3- Aminopropyl) polydimethylsiloxane, 1,3-bis (3-aminophenoxymethyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3-aminophenoxymethyl) polydimethylsiloxane, , 3, -bis (2- (3-aminophenoxy) ethyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (2- (3-aminophenoxy) ethyl) polydimethylsiloxane, 1,3-bis (3- (3-aminophenoxy) propyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3- (3-aminophenoxy) pro If pill) polydimethylsiloxane is used, silicone-modified polyamideimide can be obtained.

  In order to obtain the polyamideimide (polyamideimide resin) in the present invention by the acid chloride method, as in the case of the production of the polyimide resin, a derivative halide and a diamine of a trivalent carboxylic acid compound having an acid anhydride group described above. Are dissolved in an organic polar solvent, reacted at a low temperature (0 to 30 ° C.) to obtain a polyamideimide resin precursor (polyamide-amic acid), and then imidized.

The organic polar solvent that can be used is the same as in the case of the polyimide, and is a sulfoxide solvent (for example, dimethyl sulfoxide, diethyl sulfoxide, etc.), a formamide solvent (for example, N, N-dimethylformamide, N, N- Diethylformamide, etc.), acetamide solvents (eg, N, N-dimethylacetamide, N, N-diethylacetamide, etc.), pyrrolidone solvents (eg, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, etc.) , Phenolic solvents (eg, phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, etc.), ethereal solvents (eg, tetrahydrofuran, dioxane, dioxolane, etc.), alcoholic solvents (eg, Methanol, ethanol, Ethanol, etc.), cellosolve-based solvents (e.g., butyl cellosolve, etc.), or hexamethylphosphoramide, γ- butyrolactone.
These are desirably used alone or as a mixed solvent. The solvent is not particularly limited as long as it dissolves polyamide-amic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

The polyamide-amic acid solution obtained as described above is applied to a desired support, for example, a mold for molding to form a coating film, and this coating film is treated by heating or the like, whereby imidization is performed to form a polyamide. -Conversion from amic acid to polyamide-imide (polyamideimide).
As the imidization method, a method of dehydrating and ring-closing the amic acid by heat treatment as in the case of the polyimide and a method of chemically ring-closing using a dehydration ring-closing catalyst are used.
When dehydrating and ring-closing by heat treatment, for example, the reaction temperature is 150 to 400 ° C., preferably 180 to 350 ° C., and the heat treatment time is 30 seconds to 10 hours, preferably 5 minutes to 5 hours. When a dehydration ring closure catalyst is used, the reaction temperature is 0 to 180 ° C., preferably 10 to 80 ° C., and the reaction time is several tens of minutes to several days, preferably 2 to 12 hours. Examples of the dehydration ring closure catalyst include acid anhydrides such as acetic acid, propionic acid, butyric acid, and benzoic acid.

(B) Isocyanate method:
Examples of the trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group (derivative of a trivalent carboxylic acid having an acid anhydride group) used in the case of the isocyanate method include the following structural formula (4) and structure: The compound shown in Formula (5) can be used.

  [In Formula (4), R shows a hydrogen atom, a C1-C10 alkyl group, or a phenyl group. ]

[In the formula (5), R represents a hydrogen atom, an alkyl group or a phenyl group having 1 to 10 carbon atoms, Y is a single _{bond, -CH 2 -, - CO -} , - shows or -O- - SO ₂ . ]

Any of the derivatives represented by the above general formula can be used, but the most typical example is trimellitic anhydride. These trivalent carboxylic acid derivatives having an acid anhydride group can be used alone or in combination depending on the purpose.
A derivative of a trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group represented by the structural formula (4) or the structural formula (5) is an example of a raw material for obtaining an aromatic polyamideimide, However, it is not limited to these.
In addition to the aromatic trivalent carboxylic acid compound represented by the above structural formula (4) or structural formula (5), an aliphatic trivalent carboxylic acid compound can also be used. It can also be used in combination with an acid compound.

Next, as one isocyanate compound to be reacted with a trivalent carboxylic acid compound having an acid anhydride group and a carboxylate group in the isocyanate method, for example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 '-[2,2-bis (4-phenoxyphenyl) propane] diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3 , 4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate , 2, 2 -Diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybiphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene -2,6-diisocyanate and the like.
As the isocyanate compound, an aromatic isocyanate compound (aromatic polyisocyanate) is particularly preferably used. These aromatic polyisocyanates can be used alone or in combination.
If necessary, as part of this, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m- Aliphatics such as xylylene diisocyanate and lysine diisocyanate, alicyclic isocyanates, and trifunctional or higher polyisocyanates can also be used.

  In order to obtain the polyamideimide in the present invention by the isocyanate method, the above-described trivalent carboxylic acid derivative having an acid anhydride group and an aromatic polyisocyanate are mixed with an organic polar solvent in the same manner as in the production of the polyimide. After the solution containing the polyamideimide precursor obtained by dissolution and adjustment in the substrate is coated on the support, the polyamideimide precursor is converted into the polyamideimide by heat treatment. During the conversion to the polyamide imide by this isocyanate method, carbon dioxide gas is generated and the polyamide imide is generated without passing through the polyamic acid.

  The production | generation example of aromatic polyamideimide by the polyamide imidation at the time of using trimellitic anhydride and aromatic diisocyanate to following formula (6) is shown.

  [In the formula (6), Ar represents a divalent aromatic group. ]

As the precursor to be converted into polyimide (polyimide resin) or polyamideimide (polyamideimide resin) as described above, a material obtained by reacting a single composition as a raw material is usually used. It is also possible to combine and use precursors that have been reacted using other selected components as raw materials. Moreover, the copolymer which has a polyimide repeating unit and a polyamideimide repeating unit may be sufficient.
The thickness of the base material layer is suitably about 50 to 80 μm.

<Elastic layer>
Next, the elastic layer laminated | stacked on the said base material layer is demonstrated.
In particular, it is preferable to select an elastic layer that is as soft as possible in order to follow the surface state of the paper such as the resack paper having irregularities in the surface property of the paper as the transfer material, and an elastomer material or a rubber material is used. Is good.
In the present invention, in order to form a particle layer (spherical resin particle layer) on the surface of the elastic layer, 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.

Examples of the thermosetting resin 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. .

To the selected material, a 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 vulcanization accelerator as necessary. Mixing appropriately included.
As the resistance adjuster for adjusting the electrical characteristics, various materials already described in the description of the base material layer can be applied. However, since carbon black, metal oxide, etc. impair flexibility, it is preferable to suppress the amount used. It is also effective to use an ionic conductive agent or a conductive polymer. Moreover, you may use these together.

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.
The thickness of the elastic layer is preferably about 200 μm to 2 mm. 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, such being undesirable. 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.

<Particle layer>
Next, the particle layer laminated on the elastic layer will be described.
The material of the particle layer is not particularly limited, and spherical particles mainly composed of a resin such as an acrylic resin, a melamine resin, a polyamide resin, a polyester resin, a silicone resin, or a fluororesin can be used. Further, the surface of particles made of these resin materials may be subjected to surface treatment with a different material.
Further, the resin particles referred to here include a rubber material. A structure in which the surface of spherical particles made of a rubber material is coated with a hard resin 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. Silicone resin particles suitable for use in the present invention are commercially available, and examples include trade name: Tospearl (manufactured by Momentive Performance Materials).

In the intermediate transfer belt of the present invention, the resin particles have an average (volume average) particle diameter b of preferably 1 μm <b <6 μm, and more preferably 1.5 μm <b <4 μm. If the average particle size is 1 μm or less, the particles may not be exposed and may be buried in the elastic layer. On the other hand, if it is 6 μm or more, the adhesion strength of the particles to the elastic layer is lowered, and the electrical characteristics are also lowered, which is not preferable.
The resin particles have a Mohs hardness of 7 or less, preferably about 2 to 4. If it is higher than 7, the surface of the photoreceptor may be damaged.

<Surface condition of the belt>
Next, the belt surface state in the present invention will be described.
60% or more, preferably 65% or more, of the sum of the projected area of the exposed portion of the elastic layer and the projected area of the resin particles is the projected area of the resin particles. When the projected area of the exposed portion of the elastic layer and the projected area of the resin particle occupying the entire projected area of the resin particle (hereinafter also referred to as “particle portion occupancy (against elastic rubber portion)”) are less than 60%, There may be a problem that the secondary transfer rate decreases due to adhesion to the rubber exposed portion.

<Production of 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 material layer will be described.
While slowly rotating a cylindrical mold, for example, a cylindrical metal mold, a coating liquid containing at least a resin component (for example, a coating liquid containing a polyimide resin precursor or a polyamideimide resin precursor) is used as a nozzle or Application and casting (formation of a coating film) is performed uniformly on the entire outer surface of the cylinder by a liquid supply device such as a dispenser. Thereafter, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation speed is maintained at a constant speed and the rotation is continued for a desired time. And the solvent in a coating film is evaporated at the temperature of about 80-150 degreeC, heating up gradually while rotating. 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 or polyimidizing the polyimide resin precursor or the polyamideimide resin precursor.

After sufficiently cooling, the elastic layer is subsequently laminated.
The elastic layer can be formed on the base material layer by injection molding, extrusion molding or the like, but in the present invention, it is effective to form the elastic layer by applying an elastic layer coating solution.
In the elastic layer coating liquid, liquid resin, liquid elastomer, liquid rubber, or the like can be used. A solution in which a solvent-soluble resin, elastomer, or rubber material is dissolved in a solvent can also be used as the coating solution.

Here, a method of coating and forming on a base material layer using a rubber material will be described.
Cylindrical base material layer surface using a liquid supply device such as a nozzle or dispenser while slowly rotating a cylindrical metal mold like the base material layer with a coating solution containing at least rubber, sulfur and vulcanization accelerator Apply and cast (form a coating film) so as to be uniform throughout, and heat at 90 ° C. for 1 h at a temperature rising rate of 4 ° C./min. At this stage, the elastic layer is not vulcanized.
When sufficiently leveled, as shown in FIG. 1, the resin particle (3) is moved to the elastic layer (1) while rotating the resin particle supply member provided at the position in contact with the elastic layer (1), that is, the rotating brush (2). ) Supply to the surface. In order to form a desired amount of resin particles (3) on the elastic layer (1) and to make the particle part area ratio (projected area) of the elastic layer to 60%, for example, resin particles by a rotating brush (2) The amount of pumping in (3) can be adjusted. Next, after pressurizing with a roller (not shown), the temperature is increased to 150 ° C. at a rate of temperature increase of 4 ° C./min and heated for 1 hour or more, preferably 1 to 4 hours to add the elastic layer (1). A belt is obtained by sulfurating.
Pressurization at the roller is preferably ^{50~100N / m 2, 60~90N / m} 2 is more preferable.

  The particle layer is formed by attaching or burying resin particles on the elastic layer. When the resin particles are buried in the elastic layer, the resin particles are preferably 20% or more in the depth direction of the elastic layer. Buried within 60% or less. If it is 20% or less, particle detachment tends to occur during long-term use in an electrophotographic apparatus, resulting in poor durability. On the other hand, if it is 60% or more, the effect on transferability by the spherical resin particles is reduced, which is not preferable.

The burial rate is the rate of burying in the resin layer having a diameter in the depth direction of the particle, but the burial rate mentioned here does not mean that all particles are 20% or more and 60% or less. The numerical value when expressed by the average burial ratio when viewed in the field of view may be 10% or more and 60% or less. However, when the burial rate is 10%, 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 resin layer is the total number of particles). (5% or less). Further, the particles are preferably contained in a single state in the thickness direction with respect to the elastic layer.
[Image forming apparatus]

The seamless belt manufactured by the above-described method performs, for example, a 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 recorded. It can be suitably used as an intermediate transfer belt of a so-called intermediate transfer type electrophotographic apparatus in which secondary transfer is collectively performed on a medium, and can form an electrophotographic apparatus (image forming apparatus) capable of forming a high-quality image.
The seamless belt used in the belt constituting unit provided in the image forming apparatus according to the present invention will be described in detail below with reference to a schematic diagram of the relevant part. The schematic diagram is an example, and the present invention is not limited to this.

FIG. 3 is a schematic diagram of a main part for explaining an image forming apparatus equipped with a seamless belt obtained by the manufacturing method according to the present invention as a belt member.
The intermediate transfer unit (500) including the belt member shown in FIG. 3 includes an intermediate transfer belt (501) that is an intermediate transfer member stretched around a plurality of rollers. Around the intermediate transfer belt (501), there are a secondary transfer bias roller (605) as a secondary transfer charge applying means of the secondary transfer unit (600), and a belt cleaning blade (504) as an intermediate transfer body cleaning means. A lubricant application brush (505), which is a lubricant application member of the lubricant application means, is disposed so as to face each other.

  Further, position detection marks (not shown) are 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 passing area of the belt cleaning blade (504), which may be difficult to arrange. In this case, a position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt (501). The 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) on which the intermediate transfer belt (501) is stretched.

  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), which are primary transfer charge applying means, and a cleaning device. It is stretched between the counter roller (511) and the 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 controlled by a primary transfer power source (801) controlled by a constant current or a constant voltage so that the current or voltage is controlled to a predetermined magnitude according to the number of superimposed toner images. A bias is applied.

The intermediate transfer belt (501) is driven in the direction of the arrow by a belt drive roller (508) that is driven to rotate in the direction of the arrow by a drive motor (not shown).
The intermediate transfer belt (501) as the belt member is usually a semiconductor or an insulator and has a single-layer or multi-layer structure, but in the present invention, a seamless belt is preferably used, thereby improving durability. In addition, excellent image formation can be realized. In addition, 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), which is a secondary transfer means, is in contact with / separating means, which will be described later, with respect to the belt outer peripheral surface of a portion of the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). It is comprised so that contact / separation is possible by the contact / separation mechanism. The secondary transfer bias roller (605) sandwiches the transfer paper (P) as a recording medium between the secondary transfer counter roller (510) and the intermediate transfer belt (501) stretched between the secondary transfer counter roller (510). A transfer bias having a predetermined current is applied by a secondary transfer power source (802) that is arranged and controlled at a constant current.

  The registration roller (610) is a transfer sheet as a transfer material at a predetermined timing between the secondary transfer bias roller (605) and the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). Send (P). Further, a cleaning blade (608) as a cleaning unit is in contact with the secondary transfer bias roller (605). The cleaning blade (608) removes and removes adhering material adhering to the surface of the secondary transfer bias roller (605).

  In the color copying machine having such a configuration, when the image forming cycle is started, the photosensitive drum (200) is rotated in a counterclockwise direction indicated by an arrow by a driving motor (not shown), and the photosensitive drum (200) is rotated on the photosensitive drum (200). In addition, 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, 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. 3, 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 charged uniformly, 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 adheres to the portion where the charge of the photosensitive drum (200) remains. In other words, toner is attracted to a portion having no charge, that is, an 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 way is primary on the belt outer peripheral surface of the intermediate transfer belt (501) rotating at a constant speed while being in contact with the photosensitive drum (200). Transcribed. 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). Is done. On the photosensitive drum (200) side, the process proceeds to the C image forming process after the Bk image forming process, and reading of the C image data by the color scanner starts at a predetermined timing. A C electrostatic latent image is formed on the surface of the body drum (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 reaches, the revolver developing unit (230) is rotated, and the C developer ( 231C) is set at the development position, and 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 portion 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 device (231K). Then, the next M 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. 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.

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 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).
Then, on the intermediate transfer belt (501), the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510) and the secondary transfer bias roller (605) form a nip. When the leading edge of the toner image approaches, 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, along the transfer paper guide plate (601). The transfer paper (P) is conveyed, 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 intermediate transfer belt (501) is transferred by the transfer bias generated by the voltage applied to the secondary transfer bias roller (605) by the secondary transfer power source (802). ) The four-color superimposed toner image on the top is transferred onto the transfer paper (P) at once (secondary transfer). This transfer paper (P) is conveyed along the transfer paper guide plate (601) and passes through a portion facing the transfer paper neutralization charger (606) comprising a static elimination needle disposed downstream of the secondary transfer portion. After being neutralized by this, the belt is conveyed toward the fixing device (270) by the belt conveying device (210) which is a belt component (see FIG. 1). Then, after the toner image is melted and fixed at the nip portion 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). Stacked face up on a copy tray (not shown). 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 cleaned by the belt cleaning blade (504). The belt cleaning blade (504) is configured to contact and separate at a predetermined timing with respect to the belt outer peripheral surface of the intermediate transfer belt (501) by a cleaning member separating and contacting mechanism (not shown).

  On the upstream side of the belt cleaning blade (504) in the moving direction of the intermediate transfer belt (501), a toner seal member (502) contacting and separating from the belt outer peripheral surface of the intermediate transfer belt (501) is provided. Yes. The toner seal member (502) receives the falling toner that has dropped from the belt cleaning blade (504) during cleaning of the residual toner, and prevents the falling toner from scattering on the transfer path of the transfer paper (P). It is preventing. 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 belt 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) 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 and out of contact with the outer peripheral surface of the intermediate transfer belt (501) at a predetermined timing by a contact / separation mechanism (not shown). It has become.

  Here, at the time of repeat copying, 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 forming process. The process proceeds to the image forming process for the first color (Bk). The intermediate transfer belt (501) has two sheets 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 Bk toner image of the eye is 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 case of the single color copy mode, only the developing device 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 moved to the intermediate transfer belt (501). The copy operation is performed with the touch panel kept in contact.

In the above-described embodiment, the copying machine having only one photosensitive drum (200) has been described. However, the present invention is not limited to a plurality of photosensitive members, for example, as shown in a schematic diagram of a main part in FIG. The present invention can also be applied to an image forming apparatus in which a drum is arranged side by side along one intermediate transfer belt made of a seamless belt.
FIG. 4 shows four drums including four photosensitive drums (21BK), (21Y), (21M), and (21C) for forming toner images of four different colors (black, yellow, magenta, and cyan). 1 shows an example of the configuration of a type digital color printer.

In FIG. 4, 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 the image writing unit (12). Send to. 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, and corresponds to each color signal described above. There are four writing optical paths, and image carriers (photoconductors) (21BK), (21M), (21Y), and (21C) provided for each color of the image forming unit (13) according to the respective color signals. Perform image writing.

  The image forming unit (13) is a photoconductor (21BK), (21M), (21Y) which is an image carrier for black (BK), magenta (M), yellow (Y), and cyan (C). ), (21C). As each photoconductor for each color, an OPC photoconductor is usually used. Around each of the photosensitive members (21BK), (21M), (21Y), and (21C), there are a charging device, a laser beam exposure unit from the writing unit (12), and each color of black, magenta, yellow, and cyan Developing devices (20BK), (20M), (20Y), (20C), primary transfer bias rollers (23BK) as primary transfer means, (23M), (23Y), (23C), cleaning devices ( (Not shown), and a photosensitive member neutralizing device (not shown) are provided. 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, includes the photosensitive members (21BK), (21M), (21Y), and (21C) and the primary transfer bias rollers (23BK), (23M), and (23Y). , (23C), and the toner images of the respective colors formed on the respective photoreceptors are sequentially superimposed and transferred.

  On the other hand, the transfer paper (P) is fed from the paper feeding section (14) and then carried on the transfer conveyance belt (50), which is a belt constituting section, via the registration rollers (16). When the intermediate transfer belt (22) and the transfer conveying belt (50) come into contact with each other, the toner image transferred onto the intermediate transfer belt (22) is transferred to a secondary transfer bias roller (60) as a secondary transfer unit. ) For secondary transfer (collective transfer). Thereby, 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). After the image transferred by the fixing device (15) is fixed, the transfer paper (P) is removed from the printer main body. To be discharged.

  Residual toner remaining on the intermediate transfer belt (22) without being transferred during the secondary transfer is removed from the intermediate transfer belt (22) by the belt cleaning member (25). A lubricant application device (27) is disposed downstream 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. The parts here are based on weight.
The particle adhesion state evaluation method was performed as follows.

(Quantification of particle adhesion)
By binarizing the SEM image of the elastic rubber exposed portion / resin particle portion with the image processing software Image-plus (manufactured by cybernetics), and calculating the area ratio of the elastic rubber exposed portion and the resin particle portion, The adhesion state of the particles was quantified by the particle part occupancy (vs. elastic rubber part).

(Method for measuring adhesion strength between elastic rubber and resin particles)
Samples of the following examples in which resin particles were buried with a bending fatigue tester (manufactured by Toyo Seiki Co., Ltd.) were bent 10 times at a bending radius R = 0.38 and a bending angle 135 ° with a load of 9.8 N. And after bending 100 times, SEM observation was performed for each to determine the ease of particle detachment, and the amount of resin particle detachment was measured.
At this time, the projected area of the spherical particles relative to the sum of the projected area and the projected area of the spherical particles is defined as an initial particle partial occupancy, and the particle partial occupancy after the tenth bending is expressed as (initial particle portion The case where the occupation rate was −10)% or more was determined as OK, and the case where the ratio was less than this was determined as NG. That is, when the difference between the “partial particle occupancy after 10 times of bending” (%) with respect to the “initial particle partial occupancy” (%) in Table 1 below exceeds NG, the result is NG.
Similarly, the case where the particle partial occupancy after the 100th bending was (initial particle partial occupancy−20)% or more was determined to be OK, and the case where the particle partial occupancy was less than this was determined to be NG. That is, it is NG when the difference between the “partial particle occupancy after 100 times of bending” (%) and the “initial particle partial occupancy” (%) in Table 1 is more than 20.

(Actual machine durability evaluation)
The intermediate transfer belts of Examples 1 to 6 and Comparative Examples 1 to 3 below are used for the intermediate transfer belt of the image forming apparatus (manufactured by Ricoh) shown in FIG. Endurance evaluation was performed by passing sheets one by one, and then SEM observation was performed to observe the detached state of the particles.

(Secondary transfer rate measurement method)
The secondary transfer rate was evaluated by outputting a solid image with a single machine (manufactured by Ricoh) and measuring the amount of toner transferred from the intermediate transfer belt to the paper. The secondary transfer rate is NG of 80% or less.

[Example 1]

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; Ube Industries, Ltd.) containing a polyimide resin precursor as a main component. The dispersion of (manufactured) was prepared so that the carbon black content was 17% by weight of the polyamic acid solid content, and well mixed with stirring to prepare a coating solution for a base layer.
Next, a metal cylinder having an outer diameter of 300 mm and a length of 300 mm roughened by blasting is used as a mold, and this cylinder mold is rotated at 50 rpm (times / min) while the above-mentioned coating for the base layer is performed. The working liquid was applied with a dispenser so as to be uniformly cast on the outer surface of the cylinder. 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. Thus, the temperature was raised to 320 ° C. and heat treatment (firing) was performed for 60 minutes to form a base material layer.

H-NBR (hydrogenated nitrile rubber, ZETPOL2020L: manufactured by ZEON Corporation) 100 parts Chlorinated paraffin (Toyoparax 150, manufactured by Tosoh Corporation) 50 parts Sulfur (200 mesh sulfur, manufactured by Tsurumi Chemical Co., Ltd.) 1 part Zinc oxide (zinc flower 2 5 parts Vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1 part Processing aid (Lunac S-20, manufactured by Kao Corporation) 0.2 part Zinc hydroxystannate (ALCANEX / ZHSF, manufactured by Mizusawa Chemical Industry Co., Ltd.) After kneading a material consisting of 20 parts at 30 ° C. for 30 minutes with a kneader, it was dissolved to a solid content of 30% with methyl ethyl ketone to give a coating solution for elastic layer Prepared.
This elastic layer coating solution was uniformly cast and applied to the outer surface of the polyimide base layer using a dispenser in the same manner as the base layer. The coating amount was such that the final film thickness was 300 μm. After coating the entire surface of the base material layer, it is put into a hot air circulating dryer while rotating as it is, heated up to 90 ° C. at a heating rate of 4 ° C./min, heated for 60 minutes, and elastic before vulcanization. A layer was formed.

Silicone resin particles having an average particle diameter of 2 μm (Tospearl 120, manufactured by Momentive Performance Materials) were applied on the elastic layer before vulcanization with the apparatus shown in FIG. 1 and pressed with a roller (80 N / m ² ). Then, it was again put into a hot air circulating dryer, heated to 150 ° C. at a heating rate of 4 ° C./min, heated for 60 minutes, and vulcanized for 3 hours to obtain an intermediate transfer belt.

[Example 2]
In the same manner as in Example 1, the elastic layer coating solution was applied, the solvent was removed with a hot air circulating dryer, and then the silicone resin particle Tospearl 120 (momentive performance material) having an average particle diameter of 2 μm was applied to the rubber layer before vulcanization. 1), and pressurizing with a roller (80 N / m ² ), and then throwing it back into the hot air circulation dryer, raising the temperature to 150 ° C. at a heating rate of 4 ° C./min. Then, an intermediate transfer belt was obtained in the same manner as in Example 1 except that the vulcanization treatment was performed for 1 hour.

Example 3
In the same manner as in Example 1, the elastic layer coating solution was applied, the solvent was removed with a hot air circulating dryer, and then the silicone resin particle Tospearl 120 (momentive performance material) having an average particle diameter of 2 μm was applied to the rubber layer before vulcanization. 1) is applied with the apparatus shown in FIG. 1, and is again put into a hot air circulating dryer without pressurizing with a roller, and the temperature is increased to 150 ° C. at a rate of temperature increase of 4 ° C./min. An intermediate transfer belt was obtained in the same manner as in Example 1 except that this was performed for 1 hour.

[Comparative Example 1]
In the same manner as in Example 1, the elastic layer coating solution was applied, the solvent was removed with a hot air circulating dryer, and then the silicone resin particle Tospearl 120 (momentive performance material) having an average particle diameter of 2 μm was applied to the rubber layer before vulcanization. 1), and pressurizing with a roller (80 N / m ² ), and then throwing it back into the hot air circulation dryer, raising the temperature to 150 ° C. at a heating rate of 4 ° C./min. Then, an intermediate transfer belt was obtained in the same manner as in Example 1 except that the vulcanization treatment was performed for 30 minutes.

[Comparative Example 2]
Instead of the silicone resin particle Tospearl 120 (made by Momentive Performance Materials) having an average particle diameter of 2 μm in Example 1, the silicone resin particle Tospearl 2000B (made by Momentive Performance Materials) having an average particle diameter of 6 μm is used. An intermediate transfer belt was obtained in the same manner as in Example 1 except that.

[Comparative Example 3]
After applying the coating solution for the elastic layer in the same manner as in Example 1 and removing the solvent with a hot air circulating dryer,
Tospar 120 (Momentive Performance Materials Co., Ltd.), a silicone resin particle having an average particle diameter of 2 μm, was heated to 150 ° C. at a rate of temperature increase of 4 ° C./minute and heated for 60 minutes and vulcanized for 1 hour. 1) and applied with a roller (80 N / m ² ) to obtain an intermediate transfer belt.

[Evaluation]
The evaluation results are summarized in Table 1.

  As is apparent from the evaluation results of Table 1, according to the use of the intermediate transfer belt of the present invention, the toner transferred from the surface of the photoreceptor can be transferred to the recording material at a high transfer rate.

(Reference in FIG. 1)
DESCRIPTION OF SYMBOLS 1 Belt after elastic layer coating 2 Rotating brush 3 Spherical resin particles (symbol in FIG. 2)
P Transfer paper 70 Static elimination roller 80 Ground roller 200 Photosensitive drum 201 Photoconductor cleaning device 202 Static elimination lamp 203 Charging charger 210 Belt conveyor 230 Revolver developing unit 231Y Y developing machine 231K Bk developing machine 231C C developing machine 231M M developing machine 270 Fixing Devices 271 and 272 Fixing roller 500 Intermediate transfer unit 501 Intermediate transfer belt 502 Toner seal member 503 Charging charger 504 Belt cleaning blade 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 roller 514 Optical sensor 600 Secondary transfer unit 60 Transfer sheet guide plate 605 secondary transfer bias roller 606 transfer paper discharger 608 cleaning blade 610 a registration roller 801 primary transfer power supply 802 secondary transfer power supply (reference numeral in FIG. 3)
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 27 Lubricant application device 50 Transfer conveyance belt 60 Secondary transfer bias roller

JP-A-9-230717 JP 2007-328165 A JP 2009-75154 A

Claims (9)

  At least an elastic layer, spherical particles are attached or buried on the elastic layer to form a particle layer, and the projected area of the spherical particles relative to the sum of the projected area of the exposed portion of the elastic layer and the projected area of the spherical particles ( Hereinafter, the initial particle partial occupancy ratio is an intermediate transfer belt for an electrophotographic apparatus having a ratio of 60% or more, and a bending radius R = with an MIT tester that applies a load of 9.8 N to the belt. 0.38, when bent 10 times at a bending angle a = 135 °, particle detachment from the particle layer is within a range where the particle partial occupancy is (initial particle partial occupancy−10)% or more. An intermediate transfer belt characterized by being.   When the MIT tester is applied with a load of 9.8 N and is bent 100 times at a bending radius R = 0.38 and a bending angle a = 135 °, particle detachment from the particle layer is caused by a particle partial occupancy rate. 2. The intermediate transfer belt according to claim 1, wherein the intermediate transfer belt is in a range such that (initial particle partial occupation ratio-20)% or more.   The intermediate transfer belt according to claim 1, wherein the elastic layer is made of a thermosetting resin.   The intermediate transfer belt according to claim 1, wherein an average particle diameter b of the spherical particles is 1 μm <b <6 μm.   The intermediate transfer belt according to claim 1, wherein the spherical particles are resin particles.   The intermediate transfer belt according to claim 5, wherein the resin particles are silicone resin particles.   In the method for producing an intermediate transfer body by sequentially laminating an elastic layer on a base material layer and a particle layer in which independent spherical particles are provided in the surface direction to form an uneven shape, the elastic layer is formed on the base material layer. After the liquid is applied and heated, spherical particles having an average particle diameter b of 1 μm <b <6 μm are formed on the elastic layer by the sum of the projected area of the exposed portion of the elastic layer and the projected area of the spherical particles. A dry coating is performed so that 60% or more is the projected area of the spherical particles, and a particle layer is formed without pressurization or pressurization, and then the elastic layer is vulcanized by heating for 1 hour or more. An intermediate transfer belt manufacturing method.   A latent image forming means for forming a latent image on the image bearing member; a developing means for developing the latent image with toner to form a toner image; an intermediate transfer means for transferring the toner image to an intermediate transfer member; An image forming apparatus comprising: transfer means for transferring a toner image transferred to an intermediate transfer body to a recording medium; and fixing means for fixing the toner image transferred on the recording medium. An image forming apparatus comprising the intermediate transfer belt according to any one of 1 to 6.   9. The image forming apparatus according to claim 8, wherein the image forming apparatus is a full color image forming apparatus in which a plurality of latent image carriers having developing units for respective colors are arranged in series.