JP5445908B2 - Intermediate transfer belt for electrophotography and electrophotographic apparatus - Google Patents

Description

  The present invention relates to an intermediate transfer belt used for full-color electrophotography and an electrophotographic apparatus equipped with the intermediate transfer belt.

  In electrophotographic apparatuses, seamless belt members are used for various functions and applications in the apparatus. For example, a fixing belt, a transfer belt, a paper conveyance belt, and the like can be given.

  Among them, in a full-color electrophotographic apparatus, a four-color toner image formed on a photoreceptor is temporarily transferred to an intermediate transfer belt to form a full-color image on the intermediate transfer belt, and then transferred to paper or the like. There is an intermediate transfer belt for batch transfer to a medium.

The demand for intermediate transfer belts is rapidly increasing due to the progress of full-color copying machines. As the intermediate transfer belt, materials such as thermoplastic resin, thermosetting resin, rubber, and elastomer are used.
However, in this method, in order to obtain high speed, a method called a tandem method in which color developing devices for respective colors facing the intermediate transfer belt are arranged in series is the mainstream.

  The intermediate transfer belt used in this tandem system is required to have high strength that can withstand repeated use without causing color misregistration due to deformation during running. Polyamideimide resin is preferably used. In particular, a polyimide resin is preferably used in terms of creep deformability and durability.

  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 is locally aggregated and a part of the image is not transferred. A so-called hollow image 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 addition, the intermediate transfer belt in contact with the sheet requires not only the ability to follow the sheet but also wear resistance.
Furthermore, it is necessary to control the glossiness of the belt surface. If the glossiness is low, a malfunction occurs in the sensor using light reflection in the electrophotographic apparatus. For this reason, the required glossiness should be maintained and not lowered as the number of print outputs increases. The life of the intermediate transfer belt is shortened.
In order to solve these problems, various intermediate transfer belts in which a relatively flexible layer is laminated on a base layer have been proposed.

  Patent Document 1 proposes an elastic layer provided on a base layer and by defining the relationship between the thickness of the elastic layer and the thickness of the base layer, thereby reducing the void image and preventing the film from being damaged. However, when the thickness of the elastic layer for exhibiting the effect in this technique is provided, the thickness of the base layer is also increased. Therefore, a material having a large elastic modulus such as polyimide cannot be used as the base layer. For this reason, there are problems in creep deformation and durability.

  In Patent Document 2, it is proposed to provide environmental stability of volume resistance by defining volume resistance values of the base layer and the surface layer in the lamination, and further defining the water absorption rate of the material of the surface layer. It is not a special material to be used, and there is no mention of other physical properties, which is different from the technical idea for the intermediate belt in the present invention.

  In Patent Document 3, a binder layer having a smaller elastic layer than the base layer and excellent adhesion to the base layer is provided on the base layer, and fine transfer is performed on the base layer without causing loss of flexibility of the binder layer. We are proposing an inexpensive product that can realize durability and durability. Here, although there is a definition of the particle size of the fine particles, it is difficult to stably control the application state of the particles. Moreover, it is easy to wear and is inferior to abrasion resistance.

  Patent Document 4 proposes a structure in which a surface layer made of liquid silicone rubber is laminated on a base layer. The base layer preferably uses polyimide or polyamideimide, and the surface layer has toner releasability and elasticity, and excellent surface properties. It has been proposed to obtain. However, since silicone rubber has poor adhesion to polyimide, it is necessary to provide an adhesive layer. Moreover, since the dispersibility of carbon black is not good, the resistance is likely to vary and the production stability is poor.

  Patent Document 5 proposes using a cured methacrylic resin or a cured acrylic resin as a main component of the surface layer. However, there is no description about glossiness control, and the presence or absence of an intermediate layer is not essential, so it differs from the present invention.

  Patent Document 6 discloses an intermediate transfer belt in which an elastic layer is provided as an intermediate layer on a polyether sulfone resin base layer, and a surface layer is provided on the intermediate layer to improve followability to paper and wear resistance. Proposed. It is described that the followability is improved by providing the intermediate layer, the uneven unevenness of the unevenness of the paper and the unevenness of the color tone are improved, and at the same time, the wear resistance is obtained by providing the surface layer. However, there is no description about glossiness control, which is different from the present invention.

  In Patent Document 7, it is proposed that a layer for curing a thermosetting resin of 300 ° C. or less with a curing agent is laminated on a thermoplastic base layer. In the specification, by providing a layer imparting elasticity as an intermediate layer, it can be brought into contact with a photoreceptor or a recording medium with a wide width, and high transfer efficiency can be obtained. Further, it is described that the scratch resistance of the surface layer can be improved and the decrease in glossiness can be suppressed. However, since a thermoplastic resin is used as the base layer, deformation and change in resistance occur during the thermosetting of the surface layer, resulting in poor production stability.

  The present invention solves the above-mentioned problems of the prior art, is excellent in abrasion resistance, creep resistance, dimensional stability, durability, scratch resistance, maintains a certain surface glossiness, photoreceptors, paper, etc. Long-life full-color electrophotographic apparatus that provides a high-quality full-color image that exhibits high transfer rate and transfer performance regardless of the surface properties of the transfer medium, has no abnormal images such as voids, uneven density, and uneven color An intermediate transfer belt and a full-color electrophotographic apparatus using the intermediate transfer belt are provided.

The said subject is solved by following (1)-(7) of this invention.
(1) A three-layer structure in which an intermediate layer having a thickness of 50 to 300 μm including at least an epoxy-silicone copolymer is laminated on a base layer, and a surface layer is sequentially laminated on the intermediate layer. Intermediate transfer belt for electrophotography.
(2) An electrophotography having a three-layer structure in which an intermediate layer containing at least an epoxy-silicone copolymer is laminated on a base layer containing at least a polyimide resin, and a surface layer is sequentially laminated on the intermediate layer. Intermediate transfer belt.
(3) The intermediate transfer belt according to (1) or (2), wherein the surface layer has a pencil hardness in a range of F to 6H.
(4) The intermediate transfer belt according to any one of (1) to (3), wherein the surface layer includes at least an acrylic urethane-based curable resin.
(5) The intermediate transfer belt according to any one of (1) to (3), wherein the surface layer includes a silicone-modified polyimide resin formed by heat curing at least at 180 ° C. or more.
(6) The intermediate transfer belt according to any one of (1) to (3), wherein the surface layer includes a silicone-modified polyamideimide resin formed by heat curing at least at 180 ° C. or higher. .
(7) Electrons for performing primary transfer by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt, and performing secondary transfer of the primary transfer image collectively to a recording medium. 2. An electrophotographic apparatus according to claim 1, wherein the intermediate transfer belt is the intermediate transfer belt according to any one of items (1) to (6).

According to the present invention, by using an epoxy-silicone copolymer as an intermediate layer on the base layer, the followability to the surface property of the photoreceptor or transfer medium that is in contact with the transfer portion is good, and by using the surface layer, The wear resistance and scratch resistance are improved, and the surface 20 ° glossiness of 60 to 200 is maintained, so that no trouble occurs in the sensor in the electrophotographic apparatus, and a long-life intermediate transfer belt can be obtained.
By using a polyimide resin as the base layer, there is no dimensional change even when the electrophotographic apparatus is driven, and plastic deformation does not occur even when it is stopped for a long time. Moreover, it is excellent also in adhesiveness with the epoxy-silicone copolymer of an intermediate | middle layer.

  In addition, according to the present invention, when the pencil hardness range of the surface layer is F to 6H, high wear resistance and scratch resistance are realized without deteriorating the followability to the surface property on the paper. Can do.

Furthermore, according to the present invention, by selecting an acrylic urethane-based ultraviolet curable resin as the surface layer, it is possible to obtain an optimum hardness range, and it is possible to control the hardness as required in this region. Become.
Furthermore, according to the present invention, by selecting a silicone-modified polyimide resin that is heat-cured at 180 ° C. or higher as the surface layer, an optimum hardness range can be obtained and a surface layer having excellent scratch resistance can be obtained. be able to.
Furthermore, according to the present invention, by selecting a silicone-modified polyamideimide resin that is heat-cured at 180 ° C. or higher as the surface layer, an optimum hardness range can be obtained, and a surface layer excellent in scratch resistance can do.

  Furthermore, according to the present invention, a high-quality full-color image that exhibits high transfer performance regardless of the surface properties of a transfer medium such as a photoreceptor or paper and has no abnormal images such as voids, uneven density, and uneven color. The full-color electrophotographic apparatus can be provided.

It is a principal part schematic diagram for demonstrating the seamless belt and apparatus used for the belt structure part of the electrophotographic apparatus which concerns on this invention. FIG. 3 is a schematic diagram of a main part illustrating a configuration example in which a plurality of photosensitive drums are arranged in parallel along one intermediate transfer belt provided in a belt configuration unit of the electrophotographic apparatus according to the present invention.

[Base layer]
The base layer resin used for the electrophotographic seamless belt used in the present invention includes polyimide resin, polyamideimide resin, fluorine resin, polycarbonate resin, polyarylate resin, polybutylene terephthalate resin, polyphenylene sulfide resin, polyamide resin, polyether ether ketone. Resin, and the like. With the recent improvement in image quality and speed of full-color electrophotographic devices, there is a need for dimensional stability and high strength so that no color shift occurs even as an intermediate transfer belt. In this respect, a polyimide resin is particularly preferable as the base layer.

  The polyimide resin as the base layer resin used in the electrophotographic seamless belt used in the present invention can be any of a thermoplastic type, a solvent-soluble type, and a thermosetting type, but it is particularly necessary to blend various materials. In order to incorporate a resistance adjuster for adjusting electrical resistance, a thermosetting type is preferred in which a solution containing a polyimide precursor using an organic polar solvent (polyimide varnish) is applied and cured by thermosetting. is there.

  The polyimide precursor which is the composition of the coating liquid in the present invention and the polyimide produced by heat treatment (imidization) of the precursor will be described in detail.

<Polyimide>
The polyimide used in the present invention is first obtained via a polyamic acid (polyimide precursor) by reaction of a generally known aromatic polycarboxylic acid anhydride or derivative thereof with an aromatic diamine. That is, polyimide is insoluble in solvents and the like due to its rigid main chain structure and has an infusible property. Therefore, a polyimide precursor that is soluble in an organic solvent from an acid anhydride and an aromatic diamine ( Polyamic acid or polyamic acid) is synthesized, and at this stage, molding is performed by various methods, and then the polyamic acid is subjected to dehydration reaction by heating or a chemical method to be cyclized (imidized) to obtain polyimide. The outline of the reaction is shown in the following chemical reaction formula (I).

（式中、Ａｒ^１は少なくとも１つの炭素６員環を含む４価の芳香族残基を示し、Ａｒ^２は少なくとも１つの炭素６員環を含む２価の芳香族残基を示す。）

(In the formula, 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 aromatic polyvalent carboxylic acid anhydride include, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3 '-Benzophenonetetracarboxylic 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-dicarboxyphenyl) methane dianhydride, 2,2-bis ( 3,4-dicarbo Silphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid Dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride Products, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, and the like. These may be used alone or in combination of two or more. In addition, other (non-aromatic) polyvalent carboxylic acid anhydrides such as ethylenetetracarboxylic dianhydride and cyclopentanetetracarboxylic dianhydride are included in a range not impairing the object of the present invention (50 mol%). Can be used in combination.

  Next, specific examples of the aromatic diamine to be reacted with the aromatic polycarboxylic acid anhydride include, for example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, and p-aminobenzyl. Amine, 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) (4-amino Phenyl) sulfone, bis (4-aminophenyl) sulfur 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] propane, 2,2-bis [4- (4-aminophenoxy) phenyl Propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexa Fluoropropane, 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 [ -(3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) 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-a Minophenoxy) 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. These are used individually or in mixture of 2 or more types.

A polyimide precursor (polyamic acid) can be obtained by polymerizing the polycarboxylic acid anhydride component and the diamine component in an organic polar solvent using approximately equimolar amounts. Below, the manufacturing method of a polyamic acid is demonstrated concretely.
Examples of the organic polar solvent used in the polymerization reaction of polyamic acid include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N , N-dimethylacetamide, N, N-diethylacetamide and other acetamide solvents, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone and other pyrrolidone solvents, phenol, o-, m-, or p- Phenolic solvents such as 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 hex Methyl phosphoramide, .gamma.-butyrolactone, etc. may be mentioned, it is desirable to use them alone or as a mixed solvent. The solvent is not particularly limited as long as it dissolves polyamic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

As an example for producing a polyimide precursor, first, one or a plurality of diamines are dissolved in the above organic solvent or diffused in a slurry state in an inert gas atmosphere such as argon or nitrogen. When at least one polyvalent carboxylic 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), it opens with heat generation. A cyclopolyaddition reaction occurs, and the viscosity of the solution is rapidly increased, and a high molecular weight polyamic acid solution is obtained. The reaction temperature at this time is preferably 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, the polycarboxylic acid anhydride or derivative thereof may be first dissolved or diffused in an organic solvent, and the 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 acid dianhydride component and the diamine component is not limited. Furthermore, the tetracarboxylic dianhydride and the diamine may be simultaneously added to the organic polar solvent and allowed to react.
As described above, the polyamic acid composition is uniformly mixed in the organic polar solvent by polymerizing the polycarboxylic acid anhydride or derivative thereof and the diamine component in an organic polar solvent in approximately equimolar amounts. A polyimide precursor solution is obtained in a dissolved state.

As the polyimide precursor solution (polyamic acid solution) in the present invention, the one synthesized as described above can be used, but the so-called polyamic acid composition is simply dissolved in an organic solvent. What is marketed as a polyimide varnish can also be obtained and used.
Typical examples include Trenice (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries, Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 (manufactured by Sumitomo Bakelite Co., Ltd.), and the like. It is mentioned as a thing.

  In addition, examples of the thermoplastic type include Aurum (Mitsui Chemicals) and Vespel (DuPont). Examples of the solvent-soluble type include Rika Coat (New Nippon Rika), block copolymerized polyimide (PI Engineering), GPI (Gunei Chemical Industry) and the like. These can be used by being added to and mixed with a thermosetting type material as a subcomponent resin within a range not impairing the object of the present invention.

  A coating liquid is prepared by blending a synthesized or obtained polyamic acid solution with a compound as necessary. The coating liquid is applied to a support (molding mold) and then subjected to a treatment such as heating, whereby conversion (imidation) from polyamic acid, which is a polyimide precursor, to polyimide is performed.

As a method for converting polyamic acid to polyimide, imidization can be performed by a method (1) only by heating or a chemical method (2). The heating only method (1) is a method of converting polyamic acid to polyimide by 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 (such as a mixture of a carboxylic acid anhydride and a tertiary amine) and then heat-treated to completely imidize, (1 The method (1) is often used because it is a complicated and costly method compared to the heating only method.
However, recently, although it is a kind of the method (2), a method of promoting imidization at the time of drying by incorporating an amine such as imidazole or quinoline in the varnish as a catalyst is often employed. In order to demonstrate the intrinsic performance of polyimide, it is necessary to complete the imidization by heating above the glass transition temperature of the corresponding polyimide, but this promotes imidization at a lower temperature. It is said that mechanical durability is also improved. However, these catalysts are in very small amounts, and some of them decompose and sublime during drying, but some remain as impurities, which is not preferable.

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, nuclear magnetic resonance spectroscopy calculated from an integration ratio of 1H attributed to an amide group in the vicinity of 9 to 11 ppm and 1H attributed to an aromatic ring in the vicinity of 6 to 9 ppm. Various methods are used such as a method (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. -Lier transformation infrared spectroscopy (FT-IR method) is the most common method.

  In Fourier transform infrared spectroscopy (FT-IR method), the imidization rate is defined as follows, for example. 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), It is.

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.

In the coating solution for forming the base layer of the present invention, another resin may be used in combination with the polyimide. In addition, various materials for imparting necessary functions as an intermediate transfer belt are blended.
As a material to be blended, for example, a resistance adjusting agent, a reinforcing material, a leveling agent, a surfactant, a lubricant, an antioxidant, a catalyst, and the like can be blended. Of these, the resistance adjusting agent is particularly important.

Next, the resistance adjusting material will be described. The resistance adjusting material is indispensable for adjusting the intermediate transfer belt to a predetermined resistance value.
Any resistance control agent can be used as long as it can adjust the resistance value of polyimide. For example, carbon black, graphite, or metals such as copper, tin, aluminum, indium, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, tin doped Fillers such as metal oxide fine powders such as indium oxide, conductive polymer materials such as polyetheramide, polyetheresteramide, polypyrrole, polythiophene, polyaniline, tetraalkylammonium salt, trialkylbenzyl, ammonium Salt, alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate, glycerol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty alcohol ester, alkyl Tyne, may be used an ion-conductive material, such as lithium perchlorate. These can also be used in combination. In addition, the resistance control agent in this invention is not limited to these exemplary compounds.

In the base layer, carbon black is preferably used among the resistance control agents. As the carbon black, furnace black, acetylene black, ketjen black, channel black, and the like can be used. Oxidized carbon black obtained by oxidizing these surfaces is preferable.
Moreover, you may use a dispersing aid as needed. Furthermore, the surface functional group of carbon black and an organic compound having reactivity with the functional group may be surface-treated.

Next, a method for producing a seamless belt using the coating liquid containing the polyimide precursor will be described. For example, it is manufactured by the following process.
A dispersion preparing step for dispersing a resistance adjusting agent in a polyamic acid solution, a coating solution preparing step for adjusting the dispersion obtained by the step to the content of a predetermined resistance adjusting material, and a coating solution prepared by the step The step of applying and casting to (molding mold), the step of removing the solvent in the coating applied and cast on the support by heating, the precursor imide contained in the coating by heating at elevated temperature It is manufactured by releasing the formed thin film from the support and making it a seamless belt.

In the step of dispersing the resistance adjusting agent, there are a method of dispersing and mixing the resistance control agent directly in the polyimide precursor solution or a method of dispersing the resistance control agent in a solvent in advance and then mixing with the polyimide precursor solution.
Here, a method of dispersing carbon black as a resistance control agent will be described as an example. Note that this is an example and the present invention is not limited to this.

N-methyl-2-pyrrolidone is mixed with a small amount of carbon black and a polyimide precursor, and dispersed in a ball mill, paint shaker, bead mill or the like for a predetermined time using zirconia beads. After being dispersed to a certain particle size, the liquid taken out is used as a dispersion.
The polyimide precursor solution is mixed with the dispersion to dilute to a predetermined carbon black concentration. As a mixing method at this time, a centrifugal stirrer, a Henschel mixer, a homogenizer, a planetary stirrer, or the like can be used.
If necessary, additives such as a leveling agent and a catalyst can be added at this time. Further, after stirring, it is preferable to defoam using a vacuum defoamer or the like.

Next, the process of applying the coating solution prepared above will be described.
Examples of the method for forming a film on the support include centrifugal molding, roll coating, blade coating, ring coating, dipping, spray coating, dispenser coating, and die coating. As a method for forming a polyimide seamless belt, a centrifugal molding method is often used. However, in order to form a film on the inner surface of a support, when a layer is laminated on the surface, after film formation, the mold is once removed from the mold. It is necessary to transfer to a mold and form a surface layer by another coating method, and the process becomes complicated.
Therefore, in the case of the present invention, roll coating, dispenser coating, ring coating, die coating, and spray coating are preferable as a method for applying the coating on the outer surface of the support and sequentially laminating the base layer and the intermediate layer.

  After applying a coating solution containing polyamic acid to a predetermined film thickness on the outer surface of a metal cylindrical support that has been previously coated with a release agent by the above method, the coating film is dried using a hot air dryer, an IH heater, a far infrared heater, or the like. . In drying, first, drying is performed at a temperature of about 80 to 120 ° C. for 10 to 60 minutes, and then the temperature is increased at a temperature rising rate of about 2 to 5 ° C./min, and imidization baking is performed at 300 to 400 ° C. Do. Then, after sufficiently cooling, the surface layer is applied. The base layer, the intermediate layer, and the surface layer are not necessarily formed by the same method.

As a film thickness of the base layer formed by this invention, 50-100 micrometers is preferable. If the film thickness is too thin, the strength is insufficient and the durability is inferior, and if it is too thick, the rigidity is too large to be stably driven by a driving roller having a small curvature. The content of carbon black as the resistance adjusting agent, preferably 5-25 wt%, it is preferable that a ¹⁰ 6 ^{to 10 10} [Omega] cm as volume resistivity. If the carbon black content is too small, it is difficult to control the variation in resistance value. If the carbon black content is too large, the film is brittle and inferior in flexibility and inferior in durability. If the resistance value is too low, the toner is scattered in the non-image area at the time of transfer and the sharpness is lowered. On the other hand, if it is too high, the transfer electric field does not work well, which is not preferable in terms of transfer efficiency.

[Middle layer]
Next, the intermediate layer used in the present invention will be described.
<Epoxy-silicone copolymer>
An epoxy-silicone copolymer is used for the intermediate layer in the present invention. This copolymer resin is excellent in adhesiveness with polyimide, and can form a layer without the need for primer treatment or the like in advance. Further, since it has an appropriate flexibility, it does not crack even when the intermediate transfer belt is bent. Further, it can sufficiently follow the surface properties of the photoreceptor and the transfer medium.

  Furthermore, since it is liquid, it can be produced by the same method as that for the base layer, which is suitable for continuous production. Further, the viscosity can be adjusted with a solvent or the like as necessary, and various additive materials can be easily blended.

The epoxy-silicone copolymer of the present invention is formed by crosslinking and curing a block copolymer of an epoxy part and a silicone part.
This block copolymer uses an Si—H group or Si—OH group-containing polysiloxane as an active hydrogen group-containing material, and has an amount larger than the equivalent amount relative to the amount of the active hydrogen group (Si—H group or Si—OH group). An epoxy group-containing (residual) polysiloxane can be obtained by reacting an epoxy material such as epoxy group-containing bisphenol A-di-glycidyl ether or bisphenol F-type di-glycidyl ether with the active hydrogen group of the polysiloxane. it can. Or, as is known for a long time, it reacts with Si-H groups and Si-OH groups of polysiloxane, such as bisphenol A type double bond group-containing glycidyl ether and bisphenol F type double bond group-containing glycidyl ether. Block copolymerization of addition-reactive epoxy materials having reactive groups (double bonds such as CH = CH ₂ groups and CH = C (R) H groups) and Si-H or Si-OH group-containing siloxane units In this case, the terminal is typically an epoxy group. The
By introducing this silicone moiety, the above-described flexibility layer can be obtained. The greater the amount of silicone (especially the amount of straight silicon), the more flexible, but the amount of silicone to be introduced depends on the structure (conformation and configuration) of the epoxy group-containing site, but 40-60 wt% preferable. If it is less than 40%, it is hard and inferior in flexibility, and if it exceeds 60%, the film strength is low and it cannot withstand actual use durability.
This copolymer is polymerized by thermosetting using a general-purpose catalyst for epoxy resin and a curing agent.
As heating temperature, the heating of about 120 to 250 degreeC is required. For this reason, when a general thermoplastic resin is used, it is necessary to select one having high heat resistance because thermal deformation (shrinkage) may occur when the surface layer is heated. When such a resin is used, it is necessary to perform melt molding at a high temperature, which is not preferable for production. Therefore, polyimide is preferably used in the base layer of the present invention.

As a curing agent for the epoxy-silicone copolymer of the intermediate layer, an active hydrogen group (or precursor thereof) -containing material is used, and a di-, tri- or tetra-carboxylic acid, an acid anhydride compound, an amine compound, Polyphenol compounds are preferably used.
Examples of acid anhydrides include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, hydrogenated methylnadic acid anhydride, and trialkyltetrahydrophthalic anhydride. Acid, methylcyclohexene tetracarboxylic dianhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, ethylene glycose bisanhydrotrimellite, glycerin bis (anhydrotrimetrito) mono Examples include acetate, dodecenyl succinic anhydride, aliphatic dibasic acid polyanhydride, and chlorendic anhydride.
Examples of amine compounds include diethylenetriamine, triethylenetetramine, diethylaminopropylamine, N-aminoethylpiperazine, benzyldimethylamine, tris (dimethylaminomethyl) phenol, metaphenylenediamine, diaminophenylmethane, diaminodiphenylsulfone, polyamide resin, Examples include imidazole compounds. In particular, imidazole compounds are preferably used. For example, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methyl. Imidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-benzyl-2-methyl Imidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6- (2′-methylimidazolyl- (1 ′)-ethyl-s-triazine, 2,4-diamino-6- (2′-un) Decylimidazolyl- (1 ′)-ethyl-s-triazine, 2, 4-diamino-6- (2′-ethylimidazolyl- (1 ′)-ethyl-s-triazine, 2,4-diamino-6- (2′-methylimidazolyl- (1 ′)-ethyl-s-triazine isocyanur) Examples include acid adducts, 2-methylimidazole isocyanuric acid adducts, and imidazole silanes.
As the phenol compound, a novolac type phenol resin or a resol type phenol resin is preferably used. In addition, phenol-modified polyimide can also be used. These curing agents can be used not only alone but also in combination.

  Among these curing agents, liquid ones are preferably used because they can be easily mixed into the liquid resin. It is also possible to add a solid material by dissolving it in a solvent and mixing it. Moreover, the compounding quantity mix | blends the quantity calculated so that the epoxy equivalent of a epoxy-silicone copolymer and a reactive group equivalent may correspond.

Various additives can be blended in this resin as necessary, as in the base layer.
In particular, the formulation of the resistance adjuster will be described. As the resistance adjusting agent, the same ones as described above can be applied. In particular, carbon black is preferably used. The epoxy-silicone copolymer of the present invention has a good dispersibility with respect to carbon black and is easy to be obtained with a small variation in resistance value.

An example of the method of blending carbon black into this resin is shown below.
Carbon black and a small amount of an epoxy-silicone copolymer are mixed in a solvent and dispersed using a zirconia bead for a predetermined time with a ball mill, paint shaker, bead mill or the like. After being dispersed to a certain particle size, the liquid taken out is used as a dispersion.
The dispersion is diluted to a predetermined carbon black concentration by mixing an appropriate amount of an epoxy-silicone copolymer. Next, a predetermined amount of the curing agent is mixed.
As a mixing method at this time, a centrifugal stirrer, a Henschel mixer, a homogenizer, a planetary stirrer, or the like can be used.
If necessary, additives such as a leveling agent, a catalyst, and a lubricant can be added at this time.
Further, after stirring, it is preferable to defoam using a vacuum defoamer or the like.

In addition, an example of a method for blending carbon black into the resin is shown below.
Carbon black and a small amount of an epoxy-silicone copolymer are mixed in a solvent and dispersed using a zirconia bead for a predetermined time with a ball mill, paint shaker, bead mill or the like. After being dispersed to a certain particle size, the liquid taken out is used as a dispersion.
The dispersion is diluted to a predetermined carbon black concentration by mixing an epoxy-silicone copolymer with the dispersion. Next, a predetermined amount of the curing agent is mixed.
As a mixing method at this time, a centrifugal stirrer, a Henschel mixer, a homogenizer, a planetary stirrer, or the like can be used. If necessary, additives such as a leveling agent, a catalyst, and a lubricant can be added at this time. Further, after stirring, it is preferable to defoam using a vacuum defoamer or the like.

  Next, the obtained coating solution is applied on the base layer containing polyimide so as to have a predetermined film thickness by using a method preferably selected from the same method as described above. The final film thickness is preferably about 50 to 300 μm in order to exhibit preferable transfer performance. If it is too thin, the followability to the surface properties of the photosensitive member and the transfer medium is not sufficient, and if it is too thick, the film tends to crack at the time of driving at the curvature portion of the tension roller of the belt.

  After application, it is cured by heating in a dryer. The heating temperature is set to an appropriate temperature depending on the type of the crosslinking agent to be used, but it is preferable to cure in a temperature range of about 120 ° C to 250 ° C. After drying, it is cooled and removed from the mold to obtain a seamless belt.

[Surface layer]
Next, the surface layer used in the present invention will be described.
As the surface layer used in the present invention, acrylic resin, epoxy resin, urethane resin, silicone resin, fluorine resin, polyimide resin, polyamideimide resin, polyamide resin, phenol resin, polycarbonate resin, Cured resin or thermoplastic resin by heat, light, or electron beam such as polyarylate resin, polyester resin, polyol resin and the like can be applied, and can be appropriately selected from these.
Among these, acrylic urethane-based ultraviolet curable resins, silicone-modified polyimide resins, and silicone-modified polyamideimide resins are particularly preferable from the viewpoints of scratch resistance, releasability from toner, and toner cleaning properties.

<Acrylic urethane type UV curable resin>
For the surface layer in the present invention, it is preferable to use an acrylic urethane-based ultraviolet curable resin. This resin is excellent in adhesiveness with an epoxy-silicone copolymer resin. In addition, since it has an appropriate hardness and can control the hardness, the wear resistance and scratch resistance are improved, and the light reflection in the electrophotographic apparatus is used by maintaining the surface 20 ° glossiness of 60 to 200. The sensor has no problems and can extend the service life.

  Furthermore, since the acrylic urethane type ultraviolet curable resin is in a liquid state, it can be produced by the same method as that for the base layer, and is suitable for continuous production. Further, the viscosity can be adjusted with a solvent or the like as necessary, and various additive materials can be easily blended.

  The acrylic urethane type ultraviolet curable resin used in the present invention contains at least a polyol (crosslinkable component containing an active hydrogen group for urethane reaction with an isocyanate group), an isocyanate, and an acrylate. The physical properties of the cured resin after irradiation with ultraviolet rays are determined by the structure of the polyol, the type of isocyanate, the number of acrylic groups, and the like, and can be designed by changing the combination. By these combinations, physical properties such as the hardness of the resin, the degree of elongation, and the adhesion to the intermediate layer can be controlled.

1-hydroxycyclohexyl phenyl ketone (Irgacure 184; manufactured by Ciba Specialty Chemicals) is used as the acrylic polymerization initiator of the acrylic urethane-based ultraviolet curable resin of the surface layer of the present invention. The polymerization initiator is not limited to this.
For example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, isopropylthioxanthone, 2, Examples include 4,6-trimethylbenzoyl diphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide.
These polymerization initiators can be used not only alone but also in combination, and can be used in combination with urethane reaction initiation assistants (active hydrogen group-containing crosslinkable materials) such as amines as necessary.

  Among these polymerization initiators, liquid ones are preferably used because they can be easily mixed into the liquid resin. It is also possible to add a solid material by dissolving it in a solvent and mixing it.

  Next, the obtained coating solution is applied so as to have a predetermined film thickness on an intermediate layer containing at least an epoxy-silicone copolymer resin by using a method suitably selected from the same method as described above. The final film thickness is preferably about 0.5 to 10 μm. If it is too thin, abrasion resistance and scratch resistance will not be exhibited, and if it is too thick, the flexibility of the lower intermediate layer will be impaired, and transfer performance cannot be exhibited, which is not preferred.

After coating, it is cured with an ultraviolet irradiation device. The amount of UV exposure necessary for curing the resin varies depending on the type of resin. The irradiation conditions in the present invention are all 140 W / cm × 5 m / min × 3 passes, but are not necessarily limited to these conditions.
As for the hardness of the acrylic urethane type ultraviolet curable resin, the pencil hardness is preferably F to 6H. If the hardness is too low, sufficient hardness cannot be obtained, and wear resistance and scratch resistance cannot be obtained. Moreover, when too high, the softness | flexibility of an intermediate | middle layer of a lower layer is impaired, and since transfer performance cannot be expressed, it is not preferable.

<Silicone-modified polyimide resin>
Next, the silicone-modified polyimide resin of the present invention will be described. The silicone-modified polyimide resin can be described by the chemical formula (II).

(Wherein X is a tetravalent aromatic ring or aliphatic ring group, R ₁ , R ₂ , R ₇ are divalent organic groups, R _{3 to} R ₆ are alkenyl groups, alkyl groups, phenyl groups, or substitutions. A phenyl group, and m and n represent an integer of 3 or more)
Such a silicone-modified polyimide resin can be produced using a mixture of siloxane diamine, aromatic diamine, and tetracarboxylic dianhydride as a raw material. As the siloxane diamine compound, ω, ω′-diamino-substituted polysiloxane described in the chemical formula (III) can be preferably used.

(R ₁ and R ₆ represent a divalent organic group, R _{2 to} R ₅ represent an alkyl group, a phenyl group, or a substituted phenyl group, and n represents an integer of 5 to 50). Specifically, bis (3-aminopropyl) tetramethyldisiloxane, bis (10-aminodecamethylene) tetramethyldisiloxane, dimethylsiloxane tetramer having aminopropyl end groups, octamer, bis (3-amino And phenoxymethyl) tetramethyldisiloxane.

  The aromatic diamine used in the silicone-modified polyimide resin of the present invention is, for example, (1) a biphenyl diamine compound, a diphenyl ether diamine compound, a benzophenone diamine compound, a diphenyl sulfone diamine compound, a diphenylmethane diamine compound, 2,2- Diphenylalkane diamine compounds such as bis (phenyl) propane, 2,2-bis (phenyl) hexafluoropropane diamine compounds, diphenylenesulfone diamine compounds, (2) di (phenoxy) benzene diamine compounds, di ( “Aromatic rings (benzene rings) such as phenyl) benzene-based diamine compounds, (3) di (phenoxyphenyl) hexafluoropropane-based diamine compounds, and bis (phenoxyphenyl) propane-based diamine compounds. Etc.) two or more, in particular aromatic diamine compounds having 2 to 5 "primarily can be mentioned aromatic diamine containing them alone or can be used as a mixture.

  Examples of the aromatic diamine include diphenyl ether diamine compounds such as 1,4-diaminodiphenyl ether and 1,3-diaminodiphenyl ether, 1,3-di (4-aminophenoxy) benzene, 1,4-bis (4- Di (phenoxy) benzene-based diamine compounds such as aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane And bis (phenoxyphenyl) propane-based diamine-based compounds.

  Next, the tetracarboxylic dianhydride used in the present invention will be specifically described. As the tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride is used. 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic Acid dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, ethylene glycol bistrimellitate dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride and the like.

The silicone-modified polyimide resin used in the present invention can be produced by a known method using the compounds listed above. For example, these are heated in an organic solvent in the presence of a catalyst such as tributylamine, triethylamine, or triphenyl phosphite as necessary, and a polyimide is obtained directly. Tetracarboxylic dianhydride and diamine are reacted in an organic solvent. After obtaining polyamic acid which is a precursor of polyimide, a method of obtaining polyimide by adding a dehydration catalyst such as p-toluenesulfonic acid as necessary and imidizing by heating, or this polyamic acid, acetic anhydride Dehydrating and ring-closing agents such as acid anhydrides such as propionic anhydride and benzoic anhydride, and carbodiimide compounds such as dicyclohexylcarbodiimide and chemical ring-closing methods by adding a ring-closing catalyst such as pyridine, isoquinoline, imidazole and triethylamine as necessary There is.
The silicone-modified polyimide resin of the present invention can be appropriately changed in physical properties such as hardness depending on the combination of the silicone modification amount of the chemical formula (II), the structure of the polyimide part, etc., in order to sufficiently exhibit the scratch resistance. Are preferably those that are sufficiently heat-cured at a curing temperature of 180 ° C. or higher.
The epoxy-silicone copolymer that is the intermediate layer can be used without any problem because it does not deteriorate even at the heating temperature of the surface layer.

<Silicone-modified polyamideimide resin>
Next, the silicone-modified polyamideimide resin of the present invention will be described.
The silicone-modified polyamideimide can be described by the chemical formula (IV).

(Wherein R represents an aromatic tetracarboxylic acid residue, Ar represents an aromatic diisocyanate residue, and Siloxane represents a diaminosiloxane residue)

  Such a silicone-modified polyamideimide can be produced by a known production method. In general, as a method for producing polyamideimide, an isocyanate method (for example, Japanese Patent Publication No. 44-19274, Japanese Patent Publication No. 45-2397), an acid chloride method (for example, Japanese Patent Publication No. 42-15637) There are those described in the direct polycondensation method (for example, Japanese Patent Publication No. 49-1077) and the solution polycondensation method (for example, Japanese Patent Publication No. 40-8910), and any method can be used.

  For example, as a method using isocyanate, there is a method of synthesizing siloxane diamine, aromatic tricarboxylic acid and derivatives thereof, and diisocyanate as raw materials (for example, JP 2000-122964 A).

  Here, as the siloxane diamine compound, those represented by the chemical formula (V) can be preferably used.

(R ₁ and R ₆ represent a divalent organic group, R _{2 to} R ₅ represent an alkyl group, a phenyl group, or a substituted phenyl group, and n represents an integer of 5 to 50). Specifically, 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, bis (3-aminopropyl) tetramethyldisiloxane, bis (10-aminodecamethylene) tetra Examples thereof include methyldisiloxane, dimethylsiloxane tetramer having an aminopropyl end group, octamer, bis (3-aminophenoxymethyl) tetramethyldisiloxane, and the like.

  In the production of the silicone-modified polyamideimide of the present invention, an aromatic diamine can be mixed and used in addition to the siloxane diamine. For example, (1) biphenyl diamine compounds, diphenyl ether diamine compounds, benzophenone diamine compounds, diphenyl sulfone diamine compounds, diphenylmethane diamine compounds, diphenylalkane diamine compounds such as 2,2-bis (phenyl) propane, 2-bis (phenyl) hexafluoropropane diamine compound, diphenylene sulfone diamine compound, (2) di (phenoxy) benzene diamine compound, di (phenyl) benzene diamine compound, (3) di (phenoxyphenyl) Mainly “aromatic diamine compounds having 2 or more, especially 2 to 5 aromatic rings (benzene rings)” such as hexafluoropropane diamine compounds and bis (phenoxyphenyl) propane diamine compounds. It can be mentioned aromatic diamine containing them alone or can be used as a mixture.

  Examples of the aromatic diamine include diphenyl ether diamine compounds such as 1,4-diaminodiphenyl ether and 1,3-diaminodiphenyl ether, 1,3-di (4-aminophenoxy) benzene, and 1,4-bis (4-amino). Di (phenoxy) benzene-based diamine compounds such as phenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, and the like And bis (phenoxyphenyl) propane-based diamine compounds.

  Specific examples of the aromatic tricarboxylic acid and derivatives thereof used in the production of the silicone-modified polyamideimide of the present invention include trimellitic anhydride, trimellitic anhydride monochloride, 1,4-dicarboxy-3-N, N-dimethylcarbamoylbenzene, 1,4-dicarbomethoxy-3-carboxybenzene, 1,4-dicarboxy-3-carbophenoxybenzene, 2,6-dicarboxy-3-carbomethoxypyridine, 1,6-di Examples include carboxy-5-carbamoylnaphthalene, ammonium salts composed of the above aromatic tricarboxylic acids and ammonia, dimethylamine, triethylamine, and the like. Of these, trimellitic anhydride and trimellitic anhydride monochloride are preferred.

  Specific examples of the aromatic diisocyanate used in the present invention include 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and naphthalene-1,5-diisocyanate. O-, m-xylylene diisocyanate, 2,4-tolylene dimer, and the like. In addition, isocyanates such as hexamethylene diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), and isifolone diisocyanate can be used alone or in combination.

  As the solvent used in the production of the silicone-modified polyamideimide of the present invention, an aprotic polar solvent excellent in solubility of the produced resin is preferable. Examples of such aprotic polar solvents include dimethylacetamide, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, 4-butyrolactone, sulfolane, and cyclohexane. For the imidization reaction, N-methyl-2-pyrrolidone having a high boiling point and a high boiling point is particularly preferable.

The silicone-modified polyimide resin of the present invention can appropriately change the physical properties such as hardness by combining the silicone modification amount of the chemical formula (IV), the structure of the polyamide-imide part, etc., but sufficiently exhibits scratch resistance. For this, those which are sufficiently heat-cured at a curing temperature of 180 ° C. or higher are preferable.
The epoxy-silicone copolymer that is the intermediate layer can be used without any problem because it does not deteriorate even at the heating temperature of the surface layer.

[Intermediate transfer belt]
In the above description, the three-layer structure of the base layer, the intermediate layer, and the surface layer is not necessarily limited to this structure, and may be stacked in multiple layers as necessary.

Next, the seamless belt used in the belt constituting unit equipped in the electrophotographic apparatus according to the present invention will be described in detail below with reference to a schematic diagram of relevant parts. The schematic diagram is an example, and the present invention is not limited to this.
The schematic diagram of FIG. 1 shows a schematic configuration of the main part of an electrophotographic apparatus equipped with a belt component and the like.
The intermediate transfer unit (500) which is a belt component shown in FIG. 1 includes an intermediate transfer belt (501) which 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, a position detection mark (not shown) is provided on the outer peripheral surface or inner peripheral surface of the intermediate transfer belt (501). However, on the outer peripheral surface side of the intermediate transfer belt (501), it is necessary to devise a position detection mark that avoids the 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. Position detection is performed by detecting light reflection from the surface of the intermediate transfer belt. Therefore, detection becomes unstable when the glossiness of the surface of the intermediate transfer belt decreases or becomes non-uniform. By using the intermediate transfer belt of the present invention, it is possible to suppress a decrease in surface glossiness and to stabilize detection.

  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), which is the belt component, is usually a semiconductor or insulator and has a single layer or multilayer structure, but the seamless belt of the present invention 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) is disposed so as to sandwich the transfer paper P, which is a recording medium, between the portion of the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). A transfer bias having a predetermined current is applied by a secondary transfer power source (802) 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 the counterclockwise direction indicated by an arrow by a drive motor (not shown), and a charging charger is used according to each color. After charging by (203) and image exposure by the exposure means (L), Bk (black) toner image formation, C (cyan) toner image formation, M (magenta) toner image formation on the photosensitive drum (200) , Y (yellow) toner image formation is 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. 1, 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 machine (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 Y image forming process after the Bk image forming process, and reading of Y image data by a color scanner starts at a predetermined timing. A Y 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 (T) electrostatic latent image arrives, the revolver developing unit (230) is rotated and Y development is performed. The machine (231Y) is set at the development position, and the Y electrostatic latent image is developed with Y toner. Thereafter, the development of the Y electrostatic latent image area is continued, but when the rear end of the Y electrostatic latent image passes, the revolver developing unit is rotated in the same manner as in the previous Bk developing machine (231K). Then, the next C developing machine (231C) is moved to the developing position. This is also completed before the leading edge of the next C electrostatic latent image reaches the developing position. Note that the C and M image forming steps are the same as the Bk and Y steps described above because the color image data reading, electrostatic latent image forming, and developing operations are the same as those described above.

  The Bk, Y, C, and M 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, and is transferred along the transfer paper guide plate (601). The 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 due to 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). Conventionally, plain paper that is relatively smooth has been used as this transfer paper, but in recent years, paper with relatively rough surface properties such as recycled paper has also been used. Furthermore, photographic images are often printed using a wide variety of paper such as coated paper and embossed paper. In particular, when a paper having unevenness and patterns on its surface such as embossed paper is used, there is a problem that the toner image cannot be transferred well due to the unevenness. A conventional intermediate transfer belt made of polyimide cannot follow this uneven shape, and thus toner is not transferred to the concave portion, resulting in uneven transfer. This phenomenon results in an uneven color image having a different color tone on the pattern, particularly in a color portion where two or more colors overlap. By using the intermediate transfer belt of the present invention, it is possible to realize good transfer without causing unevenness due to the unevenness of the paper.

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). The transfer paper (P) is then transferred to the fixing device (27
After the toner images are melted and fixed at the nip portions of the fixing rollers (271) and (272) of 0), they are fed out of the apparatus main body by a discharge roller (not shown) and 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).

  A toner seal member (503) that contacts and separates from the belt outer peripheral surface of the intermediate transfer belt (501) is provided on the upstream side of the belt cleaning blade (504) in the moving direction of the intermediate transfer belt (501). Yes. The toner seal member (503) receives the falling toner dropped from the belt cleaning blade (504) during cleaning of the residual toner, and the falling toner is scattered on the transfer path of the transfer paper (P). It is preventing. The toner seal member (503) 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). This lubricant application mechanism is intended to maintain the transfer performance or cleaning performance in a good condition over the long term, but if this function is not necessary depending on the performance of the intermediate transfer belt, it is not necessary to use this function. Good. 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 copy, the operation of the color scanner and the image formation on the photosensitive drum (200) are performed at a predetermined timing following the image formation process for the fourth color (M) of the first sheet. 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 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 including only one photosensitive drum 1 has been described. However, the present invention may be configured such that, for example, a plurality of photosensitive drums as illustrated in FIG. 2 are arranged in parallel along one intermediate transfer belt. The present invention can also be applied to the image forming apparatus.
FIG. 2 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. 2, the printer 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 signal 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. An image document corresponding to each color signal is provided in an image carrier (photosensitive member) (21BK), (21M), (21Y), and (21C) having four writing optical paths and provided for each color of the image forming unit. Doing

  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 feed section (14) and then carried by 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.

  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 device (25). A lubricant application device (not shown) is disposed on the downstream side of the belt cleaning device (25). This lubricant application device 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.

  Further, position detection marks (not shown) are provided on the outer peripheral surface or inner peripheral surface of the intermediate transfer belt (22). However, on the outer peripheral surface side of the intermediate transfer belt (22), it is necessary to devise a position detection mark that avoids the passing area of the belt cleaning device (25), 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 (22). The optical sensor (28) as a mark detection sensor is provided at a position between the secondary transfer bias roller (60) and the belt drive roller (24). Position detection is performed by detecting light reflection from the surface of the intermediate transfer belt. Therefore, detection becomes unstable when the glossiness of the surface of the intermediate transfer belt decreases or becomes non-uniform. By using the intermediate transfer belt of the present invention, it is possible to suppress a decrease in surface glossiness and to stabilize detection.

  The seamless belt according to the present invention can be preferably applied to an intermediate transfer belt type image forming apparatus equipped with the intermediate transfer belt (501) or (22) as described above, and the intermediate transfer belt (501) or ( The present invention can also be applied to a transfer / conveying belt type image forming apparatus equipped with a transfer / conveying belt instead of 22). Further, in the case of an image forming apparatus using a transfer / conveying belt system, the present invention can be applied to either the 1-photosensitive drum system or the 4-photosensitive drum system.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples without departing from the gist thereof.

[Preparation of Intermediate Transfer Belt A]
[Preparation of coating solution for base layer]
First, the following constituent materials were mixed and dispersed using a zirconia bead of φ1 mm for 5 hours with a bead mill disperser to prepare a carbon dispersion.
<Dispersion constituent material for base layer>
・ Polyimide solution U-varnish A (Ube Industries solid content 18%) 2 parts by weight ・ Carbon black Special black 4 (Degussa) 10 parts by weight ・ N-methyl-2-pyrrolidone (Mitsubishi Chemical) 88 parts by weight

<Coating liquid composition material for base layer>
Using the above dispersion, the following constituent materials were mixed, mixed and defoamed with a centrifugal stirring deaerator to obtain a coating solution.
-50 parts by weight of the above carbon black dispersion-50 parts by weight of polyimide solution U-varnish A (Ube Industries; solid content 18 wt%)-0.01 parts by weight of polyether-modified silicon FZ2105 (Toray Dow Corning)

[Production of seamless belt]
Next, a metal cylinder having an outer diameter of 100 mm and a length of 300 mm having a mirror finish and a release agent applied thereto is used as a mold, and the coating is performed while rotating the cylinder at 50 rpm (times / minute). The liquid was uniformly cast on the outer surface of the cylinder using a dispenser. The coating amount was such that the final film thickness was 70 μm. When the predetermined amount was completely poured and the coating film was spread evenly, it was put into a hot air circulating dryer while rotating, heated to 100 ° C. at a heating rate of 3 ° C./min, and heated for 30 minutes. Thereafter, the rotation was stopped, the mixture was put into a heating furnace (baking furnace) capable of high temperature treatment, heated to 310 ° C. at a heating rate of 2 ° C./min, and subjected to heat treatment (baking) for 60 minutes. After stopping the heating, it was gradually cooled to room temperature.

[Preparation of coating liquid A for intermediate layer]
First, the following constituent materials were mixed and dispersed using a zirconia bead of φ1 mm for 5 hours with a bead mill disperser to prepare a carbon dispersion.
<Dispersion A constituent material for intermediate layer>
・ Epoxy-silicone copolymer ALBIFLEX 348 (silicone 60 wt% Nanoresins) 1 part by weight ・ Carbon black Special black 4 (Degussa) 10 parts by weight ・ N-methyl-2-pyrrolidone (Mitsubishi Chemical Corporation) 89 parts by weight The following constituent materials were mixed and mixed and defoamed with a centrifugal stirring deaerator to obtain a coating solution A.

<Coating liquid A constituent material for intermediate layer>
-52 parts by weight of the above carbon black dispersion A-40 parts by weight of an epoxy-silicone copolymer ALBIFLEX 348 (silicone 60 wt% Nanoresins)-8 parts by weight of methyltetrahydrophthalic anhydride HN-2000 (Hitachi Chemical Industries)

[Preparation of the intermediate layer A on the base layer]
On the polyimide base layer produced previously, the said intermediate | middle layer coating liquid A was similarly cast on the outer surface using the dispenser, and was apply | coated. The coating amount was such that the final film thickness was 200 μm. When the predetermined amount was completely poured and the coating film was spread evenly, it was put into a hot air circulating dryer while rotating, heated to 120 ° C. at a heating rate of 4 ° C./min, and heated for 30 minutes. Then, it heated up to 250 degreeC with the temperature increase rate of 4 degree-C / min, and heat-processed for 120 minutes. After stopping the heating, it was gradually cooled to room temperature.

[Preparation of surface layer coating solution A]
Each constituent material shown below was mixed.
<Coating liquid A constituent material for surface layer>
-Urethane acrylate oligomer UN-3320HA 1500mw (Negami Kogyo) 20 parts by weight-Polymerization initiator Irgacure 184 (Ciba Specialty Chemicals) 1 part by weight-2-butanone 78.5 parts by weight Film hardness: Pencil hardness 7H

[Preparation of surface layer A on intermediate layer]
The surface layer coating solution A was uniformly applied by spray coating using a spray gun on the intermediate layer made of the epoxy-silicone copolymer resin prepared earlier. The amount of application was such that the final film thickness was 1 μm. After touch-drying for 3 minutes, it was placed in an ultraviolet irradiation device and exposed (140 [W / cm] × 5 [m / min] × 3 passes) to obtain a seamless belt A.

[Preparation of Intermediate Transfer Belt B]
The following surface layer was formed on the same base layer and intermediate layer as in Example 1 to obtain an intermediate transfer belt B.

[Preparation of surface layer coating solution B]
Each constituent material shown below was mixed.
<Coating liquid B constituent material for surface layer>
-Urethane acrylate oligomer UN-901T 4000mw (Negami Kogyo) 20 parts by weight-Polymerization initiator Irgacure 184 (Ciba Specialty Chemicals) 1 part by weight-2-butanone 78.5 parts by weight Film hardness: pencil hardness 6H

[Preparation of surface layer B on intermediate layer]
The surface layer coating solution B was uniformly applied by spray coating using a spray gun on the intermediate layer made of the epoxy-silicone copolymer resin prepared earlier. The amount of application was such that the final film thickness was 1 μm. After touch-drying for 3 minutes, it was put in an ultraviolet irradiation device and exposed (140 [W / cm] × 5 [m / min] × 3 passes) to obtain a seamless belt B.

[Preparation of Intermediate Transfer Belt C]
The following surface layer was formed on the same base layer and intermediate layer as in Example 1 to obtain an intermediate transfer belt C.

[Preparation of surface layer coating solution C]
Each constituent material shown below was mixed.
<Coating material C for surface layer coating material>
-Urethane acrylate oligomer UN-904 4900mw (Negami Kogyo) 14 parts by weight-Urethane acrylate oligomer UN-7600 11500mw (Negami Kogyo) 6 parts by weight-Polymerization initiator Irgacure 184 (Ciba Specialty Chemicals) 1 part by weight-2-butanone 78.5 parts by weight coating film hardness: pencil hardness F

[Preparation of surface layer C on the intermediate layer]
The surface layer coating solution C was uniformly applied by spray coating using a spray gun on the intermediate layer made of the epoxy-silicone copolymer resin prepared earlier. The amount of application was such that the final film thickness was 1 μm. After touch-drying for 3 minutes, it was put in an ultraviolet irradiation device and exposed (140 [W / cm] × 5 [m / min] × 3 passes) to obtain a seamless belt C.

[Preparation of Intermediate Transfer Belt D]
The following surface layer was formed on the same base layer and intermediate layer as in Example 1 to obtain an intermediate transfer belt D.

[Preparation of surface layer coating solution D]
Each constituent material shown below was mixed.
<Coating liquid D constituent material for surface layer>
-Urethane acrylate oligomer UN-7600 11500mw (Negami Kogyo) 20 parts by weight-Polymerization initiator Irgacure 184 (Ciba Specialty Chemicals) 1 part by weight-2-butanone 78.5 parts by weight Coating film hardness: Pencil hardness HB

[Preparation of surface layer D on intermediate layer]
The surface layer coating solution D was uniformly applied by spray coating using a spray gun on the intermediate layer made of the epoxy-silicone copolymer resin prepared earlier. The amount of application was such that the final film thickness was 1 μm. After touch-drying for 3 minutes, it was placed in an ultraviolet irradiation device and exposed (140 [W / cm] × 5 [m / min] × 3 passes) to obtain a seamless belt D.

[Preparation of Intermediate Transfer Belt E]
The following surface layer was formed on the same base layer and intermediate layer as in Example 1 to obtain an intermediate transfer belt E.
[Preparation of coating liquid E for surface layer]
Each constituent material shown below was mixed.
<Coating liquid E constituent material for surface layer>
Silicone-modified polyimide resin SMP2001 (manufactured by Shin-Etsu Chemical Co., Ltd.) 20 parts by weight Methyl ethyl ketone 60 parts by weight Cyclohexanone 20 parts by weight

[Preparation of surface layer E on intermediate layer]
The surface layer coating solution E was uniformly applied by spray coating using a spray gun on the intermediate layer made of the epoxy-silicone copolymer resin prepared earlier. The amount of application was such that the final film thickness was 1 μm. After touch-drying for 3 minutes, heat curing was performed at 180 ° C. for 1 h, and seamless belt E was obtained. The hardness is 3H.

[Preparation of Intermediate Transfer Belt F]
The following surface layer was formed on the same base layer and intermediate layer as in Example 1 to obtain an intermediate transfer belt F.
[Preparation of surface layer coating solution F]
Each constituent material shown below was mixed.
<Surface Layer Coating Liquid F Constituent Material>
・ Silicone-modified polyamideimide resin HR13NX (manufactured by Toyobo Co., Ltd.) 30 parts by weight N-methyl-2-pyrrolidone 70 parts by weight

[Preparation of surface layer F on the intermediate layer]
The surface layer coating solution F was uniformly applied by spray coating using a spray gun on the intermediate layer made of the epoxy-silicone copolymer resin prepared earlier. The amount of application was such that the final film thickness was 1 μm. After touch-drying for 3 minutes, drying was performed at 100 ° C. for 1 hour, and further heat-curing was performed at 200 ° C. for 1 h to obtain a seamless belt F. The hardness is 2H.

[Preparation of Intermediate Transfer Belt G]
The substrate was the same except that the base layer of Example 3 was as follows.
[Preparation of base layer]
Polycarbonate resin (Iupilon E-2000 manufactured by Mitsubishi Gas Chemical Co., Ltd.) 73 parts by weight Polybutylene terephthalate resin (Novadol 5020 manufactured by Mitsubishi Kasei Co., Ltd.) 15 parts by weight Acetylene black (manufactured by Electrochemical Co., Ltd.) 12 parts by weight

  The above mixture was melt-kneaded at a temperature of 280 ° C. using a twin-screw extruder and extruded in a molten tube state from an annular die to produce a seamless belt having an inner diameter of 100 mm and a wall thickness of 150 μm.

(Comparative Example 1)
A belt H having a two-layer structure consisting only of a base layer and an intermediate layer which are not provided with a surface layer in the intermediate transfer belt A was used.

Each of the seamless belts of Examples 1 to 7 and Comparative Example 1 was equipped as the intermediate transfer belt shown in FIG. 2 and left to stand for one week in the state of being mounted on an electrophotographic apparatus, and then a solid cyan image was printed. As the paper, rippled paper FC Japanese paper (Ricoh) was used. This paper is a paper with a pattern in Japanese paper style and a smooth surface with a surface quality of 5. A solid image printed on the paper was observed to evaluate transferability.
Thereafter, each seamless belt was taken out, the 20 ° glossiness of the surface was measured, and it was again equipped as an intermediate transfer belt, and continuous 10,000 sheets were printed. Thereafter, the seamless belt was taken out, and the 20 ° glossiness of the surface was measured again. The paper used was TYPE 6200 (Ricoh). A gloss meter PG-1 (Nippon Denshoku Industries Co., Ltd.) was used for the gloss measurement. The measurement area is 10.0 × 10.6 mm.

As a result of evaluation by solid image observation, in the present invention, by providing an intermediate layer, a high transfer rate and transfer performance are exhibited regardless of the surface properties of the photoreceptor and the paper, and abnormal images such as voids and color unevenness are exhibited. However, it was confirmed that this function deteriorates when the hardness of the surface layer becomes too high. In this example, when the surface hardness is 7H (Example 1), this evaluation result is slightly lowered. In addition, it was confirmed that the surface layer of the present invention is excellent in scratch resistance and maintains a certain glossiness, but this function is lowered when the hardness of the surface layer is lowered. In this example, when the surface hardness is HB (Example 4), this evaluation result is slightly lowered. In Example 7, an abnormal image having a horizontal band shape was generated in the solid image. This was because the belt was left in the apparatus for one week and plastically deformed into a stretched shape. . In other examples, there was no such phenomenon, and it was confirmed that creep resistance and dimensional stability were improved by using a resin layer containing polyimide as a base layer.
The results are shown in Table 1.
The evaluation index for the solid image observation is that the solid density is ◎, the solid density is uniform, the density is slightly thin in the concave portion, and the x concave portion is completely removed.

  Since the required 20 ° glossiness of the belt surface is in the range of 60 to 200, and more preferably in the range of 80 to 150, the measurement of the 20 ° glossiness of the surface before and after printing in Table 1 is performed. From the results, it can be said that when the pencil hardness is F or more, the glossiness is sufficiently maintained, and the abrasion resistance and scratch resistance are excellent. Further, according to the solid image observation results shown in Table 1, when the pencil hardness is 6H or less, the solid image has no particular abnormality and the image quality is particularly good. Therefore, when the pencil hardness is 6H or less, the surface property on the photoreceptor or paper is improved. Regardless, it can be said that a high transfer rate and transfer performance are exhibited. From the above, it has excellent wear resistance and scratch resistance, maintains a certain level of surface gloss, and exhibits high transfer rate and transfer performance regardless of the surface properties of the transfer medium such as photoconductors and papers. Further, the pencil hardness range of the surface layer of the intermediate transfer belt that can realize a high-quality full-color image without an abnormal image such as uneven density and uneven color is F to 6H. According to the present invention, it is possible to extend the life of the intermediate transfer belt.

(About Figure 1)
P Transfer paper L Exposure means 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 Toner image density sensor 210 Belt transport device 230 Revolver developing unit 231Y Y developing machine 231K Bk development Machine 231C C developing machine 231M M developing machine 270 fixing device 271 fixing roller 272 fixing roller 500 intermediate transfer unit 501 intermediate transfer belt 503 toner seal member 504 belt cleaning blade 505 lubricant application brush 506 lubricant 507 primary transfer bias roller 508 belt Driving roller 509 Belt tension roller 510 Secondary transfer counter roller 511 Cleaning counter roller 512 Feed bag current detection roller 513 Toner image 51 The optical sensor 600 the secondary transfer unit 601 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 (for Fig. 2)
P transfer paper 10 printer main body 12 image writing unit 13 image forming unit 14 paper feeding unit 15 fixing device 16 registration roller 20BK developing device 20M developing device 20Y developing device 20C developing device 21BK photoconductor 21M photoconductor 21Y photoconductor 21C photoconductor 22 Intermediate transfer belt 23BK Primary transfer bias roller 23M Primary transfer bias roller 23Y Primary transfer bias roller 23C Primary transfer bias roller 24 Belt drive roller 25 Belt cleaning device 26 Belt driven roller 27 Static eliminating means 28 Optical sensor 50 Transfer conveyance belt 60 Secondary transfer bias roller 70 Bias roller

Japanese Patent Laid-Open No. 2001-100545 JP 2001-125388 A JP 2004-354716 A JP 2006-285048 A JP 2007-316622 A JP 2004-310016 A JP 2005-266793 A

Claims (7)

For electrophotography characterized by having a three-layer structure in which an intermediate layer having a film thickness of 50 to 300 μm containing at least an epoxy-silicone copolymer is laminated on a base layer, and a surface layer is sequentially laminated on the intermediate layer. Intermediate transfer belt.   An intermediate transfer for electrophotography characterized by having a three-layer structure in which an intermediate layer containing at least an epoxy-silicone copolymer is laminated on a base layer containing at least a polyimide resin, and a surface layer is sequentially laminated on the intermediate layer. belt.   The intermediate transfer belt according to claim 1, wherein a pencil hardness of the surface layer surface is in a range of F to 6H.   The intermediate transfer belt according to claim 1, wherein the surface layer includes at least an acrylic urethane-based curable resin.   The intermediate transfer belt according to any one of claims 1 to 3, wherein the surface layer includes a silicone-modified polyimide resin formed by heat curing at least at 180 ° C or higher.   The intermediate transfer belt according to any one of claims 1 to 3, wherein the surface layer includes a silicone-modified polyamideimide resin formed by heat curing at least at 180 ° C or higher.   In an electrophotographic apparatus for performing primary transfer by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt, and performing secondary transfer of the primary transfer image collectively to a recording medium An electrophotographic apparatus, wherein the intermediate transfer belt is the intermediate transfer belt according to any one of claims 1 to 6.

Images