JP5737832B2 - Intermediate transfer belt - Google Patents

Description

  The present invention relates to an intermediate transfer belt of an image forming apparatus such as a copying machine, a printer, and a facsimile, and a manufacturing method thereof.

  For the purpose of improving the image quality of an image obtained by an image forming apparatus, an intermediate transfer belt having a two-layer or three-layer structure having a rubber elastic layer formed of a rubber elastic resin or the like has been proposed (for example, see Patent Document 1). ).

  Since an intermediate transfer belt having such a rubber elastic layer is excellent in flexibility, a transfer region with a photoreceptor or the like in contact with the intermediate transfer belt can be stably formed, and added to the toner between the photoreceptor and the like. Stress is reduced. Therefore, by adopting an intermediate transfer belt having a rubber elastic layer, it is possible to achieve prevention of image dropout, improvement of fineness of fine line printing, and the like. In addition, it is known that when paper having a rough surface (rough paper) is used, the followability to the unevenness of the paper is improved, so that image degradation can be prevented.

  Further, such an intermediate transfer belt compatible with high image quality imparts rubber elasticity in the thickness direction of the belt, while toner releasability necessary for the transfer belt is also required as an important factor. That is, when transferring toner from the surface of the intermediate transfer belt to a medium such as paper, releasability with respect to the toner is required. Therefore, it is not preferable that the rubber elastic layer having adhesiveness to the toner is exposed on the surface of the intermediate transfer belt. Therefore, a resin surface layer having a low friction coefficient and excellent toner releasability is usually provided on the rubber elastic layer (see, for example, FIG. 1).

  In order to obtain a higher quality image, it is effective to make the resin surface layer as thin as possible. On the other hand, however, when the surface layer is made thin, there is a problem that the wear of the surface layer is severe and the durability is remarkably lowered. That is, the thinned surface layer causes pinholes (part where the rubber elastic layer is exposed on the surface of the intermediate transfer belt) due to friction with paper and toner with use, and filming phenomenon (toner Is a phenomenon that the toner adheres to the transfer belt and causes transfer failure).

  As described above, in the intermediate transfer belt having a multilayer structure having a rubber elastic layer, it has been very difficult to reduce the surface layer to achieve both excellent rough paper transfer performance and wear resistance (durability). . Accordingly, there has been a demand for an intermediate transfer belt that can maintain high image quality over a long period of time even if the surface layer is made thin and that is excellent in wear resistance.

Japanese Patent No. 3248455

  The present invention is excellent in abrasion resistance, and has excellent rough paper transferability and abrasion resistance by forming a surface layer that does not easily cause defects such as pinholes even if it is thinned. It is a main object of the present invention to provide an intermediate transfer belt for an image forming apparatus that is free from such problems and a method for manufacturing the intermediate transfer belt.

  The inventors of the present invention have excellent wear resistance and reduced film thickness by phase transition of the fluororesin crystal structure on the surface layer of the intermediate transfer belt from the α-type crystal structure to the β-type or γ-type crystal structure. It has been found that a surface layer in which the generation of pinholes is suppressed can be obtained. Further, the present inventors have found that an intermediate transfer belt having such a surface layer is excellent in wear resistance and can suppress the filming phenomenon of the intermediate transfer belt. Further, since the surface layer of the intermediate transfer belt can be made thin, the followability to the paper irregularities can be further improved. The present invention has been completed as a result of further studies based on these findings.

  The present invention provides the following intermediate transfer belt for an image forming apparatus.

Item 1. Intermediate transfer belt for image forming apparatus comprising at least the following three layers:
(A) a resin base layer;
(B) an elastic layer containing a rubber elastic resin, and (c) a surface layer containing a fluororesin, and in the spectrum obtained by measuring the surface layer by infrared spectroscopy (IR), it is around 870 cm ⁻¹ . When the height from the baseline of the peak that can be confirmed is 1, the peak height near 760 cm ⁻¹ is 0.2 or less, and the thickness of the surface layer is 0.5 to 4 μm.

  Item 2. Item 2. The intermediate transfer for an image forming apparatus according to Item 1, wherein the fluororesin is polyvinylidene fluoride (PVDF), a copolymer resin of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), or a mixture thereof. belt.

  Item 3. Item 3. The intermediate transfer belt for an image forming apparatus according to Item 1 or 2, wherein the surface layer contains 0.1 to 5% by weight of layered clay mineral.

  Item 4. Item 4. The intermediate transfer belt for an image forming apparatus according to Item 3, wherein the layered clay mineral is an organically modified layered clay mineral.

  Item 5. Item 5. The intermediate transfer belt for an image forming apparatus according to Item 3 or 4, wherein the surface layer is obtained by applying and drying a mixed solution obtained by dissolving or swelling a fluororesin and a layered clay mineral in an organic solvent.

  Item 6. Item 6. The intermediate transfer belt for an image forming apparatus according to Item 5, wherein the organic solvent is an aprotic polar solvent or a mixed organic solvent of an aprotic organic solvent and another organic solvent.

  Item 7. In the above item 6, the aprotic polar solvent is at least one selected from the group consisting of N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone. The intermediate transfer belt for an image forming apparatus as described.

  Item 8. Item 3. The intermediate transfer belt for an image forming apparatus according to Item 1 or 2, wherein the surface layer is obtained after film formation by holding for 25 hours or more at a temperature not lower than the glass transition point of the fluororesin and not higher than the melting point.

Item 9. The intermediate transfer belt for an image forming apparatus according to any one of Items 1 to 8, wherein the surface layer has a volume resistivity of 10 ¹² Ω · cm or more and a static friction coefficient of 0.1 to 1.

  Item 10. Item 10. The intermediate transfer belt for an image forming apparatus according to any one of Items 1 to 9, wherein the rubber elastic layer has a type A hardness of 30 to 80 ° and a thickness of 100 to 300 µm.

  Item 11. Item 11. The intermediate transfer belt for an image forming apparatus according to any one of Items 1 to 10, wherein the surface layer is formed by a centrifugal molding method.

  The present invention is excellent in abrasion resistance and has excellent rough paper transferability and abrasion resistance (durability) by forming a surface layer that is less likely to cause defects such as pinholes even if it is thinned, and Further, it is possible to provide an intermediate transfer belt for an image forming apparatus that is free from problems such as filming. Further, since the rubber elasticity of the elastic layer can be effectively expressed by the thinned surface layer, the followability to paper is improved, thereby realizing excellent image quality.

  Such an intermediate transfer belt for an image forming apparatus according to the present invention can provide excellent image quality over a long period of time and has excellent durability. Therefore, the copying machine (including a color copying machine), a printer, and a facsimile machine. It can be suitably used as an intermediate transfer belt of an image forming apparatus employing an electrophotographic system.

2 is a schematic cross-sectional view of an intermediate transfer belt of the present invention. FIG. In this invention, it is a schematic diagram of the apparatus used for film forming. It is IR spectrum before correction | amendment and after correction | amendment. It is IR spectrum of the surface layer in Example 1 and Comparative Example 1. It is IR spectrum of the surface layer in Example 7 and Comparative Examples 1, 4, and 5. It is a figure which shows the peak height of 760 cm < ^-1 > vicinity.

1. Intermediate transfer belt for image forming apparatus The intermediate transfer belt of the present invention has at least 3 (a) a base layer made of resin, (b) an elastic layer containing a rubber elastic resin, and (c) a surface layer containing a fluororesin. In the spectrum obtained by measuring the surface layer by infrared spectroscopy (IR), the height from the baseline of the peak that can be confirmed in the vicinity of 870 cm ⁻¹ was set to 1. In this case, the peak height near 760 cm ⁻¹ is 0.2 or less, and the thickness of the surface layer is 0.5 to 4 μm.

  Hereinafter, each layer will be described.

1.1 (a) Base material layer The base material layer in the intermediate transfer belt of the present invention is made of a material having excellent mechanical properties in order to avoid deformation of the belt due to stress applied during driving. The base material layer is a layer in which a conductive agent is dispersed in a resin, and is formed of a composition for forming a base material layer containing a resin and a conductive agent.

  Examples of the resin include polyimide, polyamideimide, polycarbonate, polyvinylidene fluoride (PVdF), ethylene-tetrafluoroethylene copolymer, polyamide, polyphenylene sulfide, and a mixture thereof.

  The polyimide is usually produced by condensation polymerization of tetracarboxylic dianhydride and diamine or diisocyanate as monomer components by a known method. Usually, tetracarboxylic dianhydride and diamine are reacted in a solvent such as N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to form a polyamic acid solution, and a conductive agent described later is further added to a polyamic acid. It can disperse | distribute in a solution and can be set as the composition for base-material layer formation.

  Examples of the solvent used in this case include NMP, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoamide, 1,3-dimethyl-2-imidazo An aprotic organic polar solvent such as lysinone can be mentioned, and these can be used alone or in admixture of two or more. Among these, NMP is preferable.

  Examples of tetracarboxylic dianhydrides include pyromellitic acid, naphthalene-1,4,5,8-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, 2,3,5,6-biphenyl. Tetracarboxylic acid, 2,2 ′, 3,3′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic acid, 3 , 3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, azobenzene-3,3 ′, 4,4′-tetracarboxylic acid, bis (2, 3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane, β, β-bis (3,4-dicarboxyphenyl) propane, β, β-bis (3,4-dical) Kishifeniru) dianhydride such as hexafluoropropane, and the like.

  Examples of the diamine include m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminochlorobenzene, m-xylylenediamine, p-xylylenediamine, 1,4 -Diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4'-diaminobiphenyl, benzidine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 3,4'-diamino Diphenyl ether, 4,4′-diaminodiphenyl ether (ODA), 4,4′-diaminodiphenyl sulfide, 3,3′-diaminobenzophenone, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminoazobenzene, 4,4 '-Diaminodiphenylmethane, β, β-bis (4-aminophen Nyl) propane and the like.

  Examples of the diisocyanate include compounds in which the amino group in the diamine component described above is substituted with an isocyanate group.

  Polyamideimide is produced by condensation polymerization of trimellitic acid and diamine or diisocyanate by a known method. In this case, the same diamine or diisocyanate as the above-mentioned polyimide raw material can be used. Moreover, as a solvent used in the case of polycondensation, the same thing as the case of a polyimide can be mentioned.

  Examples of the conductive agent dispersed in the base material layer include conductive carbon-based materials such as carbon black and graphite; metals or alloys such as aluminum and copper alloys; and further tin oxide, zinc oxide, antimony oxide, and indium oxide. , Conductive titanic oxides such as potassium titanate, antimony oxide-tin oxide composite oxide (ATO), indium oxide-tin oxide composite oxide (ITO), and the like. Two or more kinds can be used in combination. As a conductive agent blended in the base material layer of the present invention, a conductive carbon-based material is preferable, and carbon black is more preferable.

  The content of the conductive agent is usually about 5 to 30% by weight in the base material layer (about 5 to 30% by weight in the solid content of the base layer forming composition). Thereby, the conductivity suitable for the intermediate transfer belt is imparted to the base material layer.

  The solid content concentration of the substrate layer forming composition is preferably 10 to 40% by weight.

  The method for preparing the composition for forming the base material layer is not particularly limited, but it is a ball mill after compounding since it can be a solution composition in which a conductive agent such as carbon black is uniformly dispersed. Etc. are preferably mixed.

  The thickness of the base material layer is usually 30 to 120 μm and preferably 50 to 100 μm in consideration of stress and flexibility applied to the belt during driving.

1.2 (b) Elastic layer The elastic layer in the intermediate transfer belt of the present invention is provided mainly for the purpose of improving the followability to the unevenness of the paper and avoiding line breakage due to stress concentration on the toner during transfer. . The rubber elastic layer is a layer in which a conductive agent is dispersed in a rubber elastic resin, and is formed of a rubber elastic resin (liquid) and a composition for forming an elastic layer containing a conductive agent.

  The rubber elastic resin is not particularly limited as long as the resin has rubber elasticity. For example, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), silicone rubber, fluorine rubber And butyl rubber (IIR), acrylic rubber (ACM), urethane rubber and the like. Among these, silicone rubber, fluorine rubber, butyl rubber, acrylic rubber, and urethane rubber are preferable.

  Examples of the silicone rubber include addition-type liquid silicone rubber, and specific examples include KE-106 and KE1300 manufactured by Shin-Etsu Chemical Co., Ltd.

  Examples of the fluororubber include vinylidene fluoride-based fluororubber (FKM), tetrafluoroethylene-propylene-based (FEPM), tetrafluoroethylene-perfluorovinylether-based (FFKM), and specifically, Daikin Industries Examples include fluorine rubber coating materials GLS-213F and GLS-223F manufactured by Co., Ltd., and fluorine rubber coating materials FFX-401161 manufactured by Taihei Kasei Kogyo Co., Ltd.

  Examples of butyl rubber include isobutylene-isoprene copolymer.

  Acrylic rubber is a rubber-like elastic body that can be obtained by polymerization of acrylic acid ester or copolymerization based on it.

  Urethane rubber can be obtained by a polyaddition reaction of polyol and diisocyanate. What is necessary is just to mix the mixing ratio of the polyol which is a raw material, and diisocyanate so that the NCO group of diisocyanate may be about 1-1.2 equivalent with respect to 1 equivalent of active hydrogen of a polyol. Moreover, the prepolymer which advanced polymerization of a polyol and diisocyanate can also be used, In this case, you may add diisocyanate or a polyol to a prepolymer as a hardening | curing agent further. Moreover, in order to lengthen a pot life, you may use what blocked the NCO terminal of the diisocyanate prepolymer with the blocking agent.

  Examples of urethane rubber include polyester-based urethane rubber (AU) whose main chain is an ester bond and polyether-based urethane rubber (EU) whose main chain is an ether bond. Specifically, Dai Nippon Ink Co., Ltd. ) Urehyper RUP1627 (polyurethane elastomer) and the like.

  The solvent for dissolving the rubber elastic resin in a solvent to form a liquid is not particularly limited. For example, aromatic solvents such as toluene and xylene; esters such as butyl acetate, isopropyl acetate, and ethyl acetate Solvents: ketone solvents such as methyl ethyl ketone and acetone; amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide; or a mixed solvent thereof may be used. One or two or more of these solvents may be used. Among these, toluene, xylene, isopropyl acetate, and butyl acetate are preferable.

  The conductive agent exemplified in the above (a) base material layer is also blended in the elastic layer. The content of the conductive agent is usually about 5 to 30% by weight in the elastic layer (about 5 to 30% by weight in the solid content of the elastic layer forming composition). This imparts conductivity suitable for the intermediate transfer belt to the elastic layer.

  Moreover, a hardening | curing agent can be added to the said composition for elastic layer formation as needed.

  For example, when the rubber elastic resin is a silicone rubber, a vinyl group-containing organopolysiloxane can be used as a main agent, and a hydrogen organopolysiloxane can be used as a curing agent. Silicone rubber can be obtained by curing these main agent and curing agent by a hydrosilylation reaction under a platinum catalyst. The curing (crosslinking) reaction is usually carried out in a two-pack type, in which the main agent and curing agent are blended on one side, and the main agent and catalyst are blended on the other side. Both liquids are mixed and used immediately before film formation. In this case, the addition amount of the curing agent may be about 5 to 20 parts by weight with respect to 100 parts by weight of the main agent.

  When the rubber elastic resin is urethane rubber, diisocyanate or polyol can be used as a curing agent.

  The solid content concentration of the elastic layer forming composition can be appropriately set depending on the production method, but is usually preferably about 20 to 70% by weight including a conductive agent, a curing agent and the like.

  The method for preparing the elastic layer forming composition is not particularly limited, but it can be a solution composition in which a conductive agent such as carbon black is uniformly dispersed. It is preferable to mix using.

  The thickness of the elastic layer is usually 50 μm or more, preferably 50 to 300 μm, more preferably 100 to 300 μm, and even more preferably 150 to 300 μm in consideration of prevention of stress concentration of the nip pressure.

  The type A hardness (JIS K6253) of the elastic layer is preferably 80 ° or less, more preferably 30 to 80 °, and even more preferably 30 to 70 °. Here, the type A hardness is a value indicating the softness of rubber. When the type A hardness exceeds 80 °, the elastic layer is too hard and the followability is inferior when uneven paper is used, and the stress is concentrated at the place where the toner is concentrated on the primary transfer. It tends to be easy to cause. On the other hand, if the type A hardness is less than 30 °, the stress generated when the belt is driven tends to concentrate on the surface layer, and sufficient durability tends not to be obtained.

  As a preferred embodiment of the elastic layer of the present invention, an elastic layer having a type A hardness of 30 to 80 ° and a thickness of 100 to 300 μm; a type A hardness of 30 to 70 ° and a thickness of 150 to 300 μm An elastic layer is exemplified.

1.3 (c) Surface Layer The surface layer in the intermediate transfer belt of the present invention is a layer for directly placing toner, transferring the toner to paper, and releasing it, and is required to have excellent surface accuracy.

  Usually, it is known that when a composition containing a fluororesin is melt-formed, it has an α-type crystal structure. However, when the fluororesin contained in the surface layer has an α-type crystal structure, the intermediate transfer belt including the surface layer has poor surface accuracy. However, by phase transition of this α-type crystal structure to β-type or γ-type crystal structure, even if the surface layer is made thin, it has excellent durability (particularly wear resistance) and can suppress the generation of pinholes. I found it. The intermediate transfer belt of the present invention having such a surface layer is excellent in durability and does not cause problems such as filming.

If the crystal structure of the fluorine resin is type alpha, infrared spectroscopy in (IR) spectrum, 760 cm around ^-1 (about 755～765Cm ^-1) and 790 cm ^-1 vicinity (about 785～800Cm ^-1) to alpha-type A peak derived from the crystal structure can be confirmed. On the other hand, if the crystal structure is β-type or γ-type fluororesin, in the IR spectrum in the vicinity of and around 790 cm ^-1 760 cm ^-1 derived from α-type crystal structure structure, a clear peak can not be confirmed, 810 cm ^-1 Peaks derived from the β-type or γ-type crystal structure can be confirmed in the vicinity (about 805 to 815 cm ⁻¹ ) (γ type) and in the vicinity of 830 cm ⁻¹ (about 825 to 835 cm ⁻¹ ) (β and γ type).

From the IR peak ratio derived from each crystal structure, the structure of the fluororesin of the surface layer can be determined. Specifically, in a spectrum obtained surface layer was measured by infrared spectroscopy (IR), 760 cm around ^-1 for a 1 the height from the baseline of the peak that can be identified around 870 cm ^-1 The peak height is 0.2 or less. The IR measurement method is measured by the method described in the examples. The peak that can be confirmed in the vicinity of 870 cm ⁻¹ is a peak derived from the C—F bond of the fluororesin. As the fluororesin, polyvinylidene fluoride (PVdF), vinylidene fluoride (VdF), and hexafluoropropylene (HFP). When the copolymer (VdF-HFP copolymer) or a mixture thereof is used, this peak always appears.

  In addition, the IR spectrum data usually has a tilt or undulation in the base line due to the influence of light scattering of the sample or the influence of apparatus noise. In the present invention, this inclination or undulation is corrected using commercially available software, and the peak height is measured. Examples of apparatuses that can perform such correction include Spectrum (manufactured by Perkin Elmer). Baseline correction was performed using automatic baseline correction (Automatic Correction command) of the above software. By using this command, it is possible to automatically baseline correct the entire spectral data range.

  For example, FIG. 3 shows a spectrum (thin line) before correction, and a corrected spectrum (thick line) after correcting the spectrum. As shown in FIG. 3, by correcting, the inclination of the spectrum before correction can be corrected to obtain a parallel spectrum. In the case of FIG. 3, the peak baseline substantially coincides with the horizontal axis of 100% transmittance.

In the present invention, when the height from the baseline of the peak that can be confirmed in the vicinity of 870 cm ^{−1 is 1} in the spectrum obtained by measuring the corrected surface layer by infrared spectroscopy (IR). The peak height that can be confirmed in the vicinity of 760 cm ⁻¹ is 0.2 or less, more preferably 0.15 or less, and particularly preferably 0.1 or less.

If the peak height is 0.2 or less, the crystal structure of the fluororesin contained in the surface layer is sufficiently phase-shifted from α-type to β-type or γ-type. Therefore, the smaller the peak height ratio in the vicinity of 760 cm ⁻¹ , the better, and the closer to 0, the better. In the present invention, the ratio of peak heights in the vicinity of 760 cm ⁻¹ is within the above range, so that even if the surface layer is thinned, the generation of pinholes can be suppressed, and the resulting intermediate transfer belt is durable. It has excellent properties and does not cause problems such as filming.

  In the present invention, it is only necessary that the crystal structure of the fluororesin contained in the surface layer can be phase-shifted from α-type to β-type or γ-type, and the method is not limited. A method of blending a layered clay mineral (hereinafter referred to as method (i)), a method of maintaining at a temperature not lower than the glass transition point of the fluororesin and not higher than the melting point for 25 hours or longer after film formation (hereinafter referred to as method (ii)) A method can be mentioned.

  Each method will be described below.

(1) Method (i)
In the method (i), a surface layer is formed using the surface layer forming composition (i) containing a fluororesin and a layered clay mineral.

  The layered clay mineral used in the present invention is a layered compound having a surface charge in a solution, and has a crystal structure in which a sheet structure in which polyhedrons such as a Si tetrahedron and an Al octahedron are arranged on a plane is layered. It is a compound having an ion adsorption site between layers.

  Examples of the layered clay mineral include smectite and hydrotalcite. In the present invention, it is preferable to use smectite (particularly, organically modified synthetic smectite). There is an ion adsorption site between smectite layers, and it has the feature of adsorbing various compounds in solution. Moreover, when water or an organic solvent enters between the layers, the volume swells by a factor of ten (swellability).

  Examples of compounds classified as layered clay minerals include montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, mica and the like. Among these, montmorillonite is preferable.

  These layered clay minerals may be natural products or synthetic products. For example, as synthetic montmorillonite, Kunipia F manufactured by Kunimine Industry Co., Ltd .; as synthetic hectorite, Laportite XLG, Laponite RD manufactured by Laporte, Lucentite SWN manufactured by Corp Chemical Co., etc .; Kunimine Industries as synthetic saponite Smecton SA manufactured by Co., Ltd. can be mentioned, and these can be obtained commercially.

  For example, montmorillonite is formed by overlapping sheet-like silicate layers having a thickness of about 1 nm and a length of about 100 nm, and the distance between the layers is about 10 mm. When water or an organic solvent enters between the silicate layers, the interlayer distance is swollen to about 50 mm.

  In the present invention, the layered clay mineral can be organically modified and used. By carrying out the organic modification treatment, the lamellar clay mineral that swells only in water swells even in the organic solvent and the interlayer distance increases, and the polymer chain dissolved in the organic solvent easily enters the interlayer of the lamellar clay mineral and dispersibility. The effect of improving is known. The organic modification treatment includes quaternary ammonium salts such as dimethylstearyl ammonium salt and trimethylstearyl ammonium salt, modification treatment by layer surface modification with an anionic polymer, end face modification treatment with alkyltrialkoxysilane, carboxyvinyl polymer, The thing which combined the polar organic solvent is mentioned. In addition to ammonium salts, phosphonium salts and imidazolium salts can also be used.

  Such organically modified layered clay minerals include, as organically modified montmorillonites, esben and organite manufactured by Hojun Co., Ltd., Nanomer manufactured by Nanocor, Cloisite manufactured by SouthernClay Products, and the like; manufactured by Corp Chemical Co., Ltd. Lucentite SPN, Lucentite SEN, Lucentite STN, etc .; Examples of organically modified synthetic mica include Somasif MPE manufactured by Corp Chemical Co., Ltd., which are commercially available.

  The said layered clay mineral can be used individually by 1 type or in combination of 2 or more types.

  The blending ratio of the layered clay mineral is preferably 0.1 to 5% by weight, more preferably 0.5 to 5% by weight, and 1 to 5% by weight based on the total weight of the surface layer. Is more preferable, and it is especially preferable that it is 1-3 weight%. By blending the layered clay mineral at such a ratio, the crystal structure of the fluororesin contained in the surface layer can be phase-shifted from α-type to β-type or γ-type, and the surface layer of the intermediate transfer belt is made into a thin film Even if it is made, pinholes are hardly generated and excellent rough paper transfer performance and durability can be realized.

  Here, the excellent rough paper transfer performance means that white paper with severe unevenness such as bond paper is printed in solid magenta color, and the toner loading in the deepest part (concave part) is visually judged. It means that there is no omission and transfer is performed without unevenness.

  Examples of the fluororesin used for the surface layer include polyvinylidene fluoride (PVdF), a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP) (VdF-HFP copolymer), or a mixture thereof. . In addition, when using a VdF-HFP copolymer, about 1-15 mol% is preferable and the ratio of HFP is more preferable about 3-12 mol%.

  The surface layer formed by using the fluororesin as described above is less susceptible to electrical conductivity due to changes in the environment (temperature, humidity, etc.), enabling stable primary and secondary transfer of toner, and high image quality. Can be realized.

  Among the above fluororesins, it is preferable to use a VdF-HFP copolymer resin which is a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and the molar ratio thereof is VdF / HFP = 20/80. -80/20 is preferable, and VdF / HFP = 50 / 50-80 / 20 is preferable.

  The blending ratio of the fluororesin can be appropriately set based on the blending ratio of the layered clay mineral, and is preferably about 95 to 99.9% by weight with respect to the total weight of the surface layer, for example, 95 to 99.5. The weight percent is more preferred, and the range of 97 to 99 weight percent is more preferred.

  The surface layer forming composition (i) can be prepared by dissolving or swelling the fluororesin and the layered clay mineral in an organic solvent.

  The organic solvent in which the fluororesin and the layered clay mineral are dissolved or swollen is not particularly limited as long as it can dissolve the fluororesin and can dissolve and swell the layered clay mineral. A mixed organic solvent of an aprotic polar solvent and another organic solvent is used.

  Examples of the aprotic polar solvent include N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone and the like. A combination of more than one species can be used.

  Examples of other organic solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; or a mixed solvent thereof.

  The solid content concentration of the surface layer forming composition (i) is preferably 0.5 to 10% by weight.

(2) Method (ii)
After forming the composition for forming a surface layer (ii) containing a fluororesin, it is maintained from the α-type crystal structure to the β-type by holding for 25 hours or more at a temperature not lower than the glass transition point and not higher than the melting point of the fluororesin included in the surface layer. Alternatively, the phase can be changed to a γ-type crystal structure. At this time, it is preferable that the formed surface layer is held under the above-described conditions in a state where it is fixed to a mold such as a cylindrical mold.

  Examples of the fluororesin and the solvent contained in the surface layer forming composition (ii) include the same as those of the surface layer forming composition (i). Further, the solid content concentration of the surface layer forming composition (ii) may be the same as that in the case of the surface layer forming composition (i). Moreover, the said surface layer formation composition (i) can also be used suitably.

  The holding temperature may be not less than the glass transition temperature of the fluororesin contained in the surface layer and not more than the melting point, preferably 2 to 10 ° C. lower than the melting point of the fluororesin contained in the surface layer, and 2 to 5 ° C. lower than the melting point. More preferably, it is temperature. The specific temperature depends on the composition of the fluororesin and cannot be determined unconditionally. For example, when PVdF is used as the fluororesin, the temperature is preferably 160 to 168 ° C., and a copolymer of VdF and HFP (VdF / When HFP = 85/15 to 99/1 (molar ratio)) is used, 132 to 140 ° C. is preferable.

  The holding time is preferably 25 hours or longer. If the holding time is less than 25 hours, the α-type crystal structure tends to be unable to sufficiently undergo phase transition to the β-type or γ-type crystal structure. Further, when the holding time is 25 hours or more, a surface layer having a sufficient β-type or γ-type crystal structure ratio can be obtained, and excellent rough paper transferability and durability can be realized. Further, the upper limit value of the retention time is not particularly limited, and the longer the retention time, the better the ratio of β-type or γ-type crystal structure increases. However, since the same surface physical properties as those obtained when held for 25 hours can be obtained even if held for 30 hours or longer, the upper limit is preferably about 50 hours (preferably about 30 hours) from the viewpoint of productivity.

  As described above, in the IR spectrum of the surface layer produced by two specific methods, a peak derived from the β-type or γ-type crystal structure can be confirmed, and it can be confirmed from IR that the crystal structure has changed. However, in the present invention, the method is not limited to these, and any method can be used as long as the crystal structure of the fluororesin contained in the surface layer can be phase-shifted from α-type to β-type or γ-type. Can also be adopted.

  The thickness of the surface layer is 0.5 to 4 μm, preferably 0.5 to 3 μm, and more preferably 1 to 3 μm. If the thickness of the surface layer exceeds the above range, the rubber elasticity of the elastic layer tends to be impaired, and if the thickness of the surface layer is below the above range, the surface layer has a higher capacitance but is more likely to be perforated. Tend to cause problems.

  The surface roughness (Rz) of the surface layer is not particularly limited, but is preferably 0.1 to 1.5 μm, more preferably 0.25 to 1.2 μm, 0.4 More preferably, it is ˜1 μm. If the surface roughness is less than 0.1 μm, it tends to stick to a sliding member such as a roll, which tends to cause torque over during driving. If it exceeds 1.5 μm, It tends to cause image defects such as sticking (filming) and voids, which is not preferable.

  The static friction coefficient of the surface layer is not particularly limited, but is preferably 0.1 to 1, more preferably 0.2 to 0.8, from the viewpoint of preventing blade noise. More preferably, it is -0.6.

The volume resistivity of the surface layer is usually 10 ¹² Ω · cm or more, and preferably 10 ¹² to 10 ¹⁵ Ω · cm.

1.4 Intermediate transfer belt The intermediate transfer belt according to the present invention comprises at least three layers having the above-mentioned (a) resin base layer, (b) an elastic layer containing a rubber elastic resin, and (c) a surface layer containing a fluororesin. The average total thickness of the transfer belt is usually preferably about 150 to 420 μm and about 200 to 400 μm. The thickness of each layer can be appropriately set within the range of the thickness of each layer in consideration of the stress and flexibility applied to the belt at the time of driving, but the ratio of the thickness of each layer is usually when the base material layer is 1 The elastic layer is about 1.5 to 5.0 (preferably about 2 to 4); the surface layer is about 0.005 to 0.05.

  The surface friction coefficient of the intermediate transfer belt of the present invention is preferably from 0.1 to 1, and more preferably from about 0.2 to 0.8.

The surface resistivity of the intermediate transfer belt of the present invention is preferably about 1 × 10 ¹⁰ to 1 × 10 ¹⁵ Ω / □, and the volume resistivity is 1 × 10 ⁸ to 1 × 10 ¹⁴ Ω · cm. It is preferable to be in the range, and it is variable within this range depending on the amount of the conductive agent added to the elastic layer and / or the base material layer.

  Since the intermediate transfer belt of the present invention can provide excellent image quality over a long period of time and has excellent durability, an electrophotographic system such as a copying machine (including a color copying machine), a printer, or a facsimile is employed. The image forming apparatus can be suitably used as an intermediate transfer belt.

2. Method for Producing Intermediate Transfer Belt for Image Forming Apparatus of the Present Invention The method for producing each layer of the intermediate transfer belt for image forming apparatus of the present invention is not particularly limited, but includes the method (i) as described above. It can be produced by a method (hereinafter referred to as production method (i)) or a method including method (ii) (hereinafter referred to as production method (ii)). The production method of the present invention will be described below.

2.1 Manufacturing method (i)
Manufacturing method (i) includes the following steps.
(1) A step of forming a base material layer by centrifugal molding or melt extrusion molding of a resin,
(2a) Centrifugal molding of a mixed solution obtained by dissolving or swelling a fluororesin and a layered clay mineral in an organic solvent using a cylindrical mold having a surface roughness (Rz) of 0.1 to 1.5 μm A step of forming a surface layer having a thickness of 0.5 to 4 μm,
(3) A step of forming an elastic layer having a thickness of 50 μm or more by centrifugal molding on the inner surface of the surface layer obtained in (2a) to form a two-layer film, and (4) the above ( A step of superposing the outer surface of the base material layer obtained in 1) and the inner surface of the elastic layer of the two-layer film obtained in (3) above, and subjecting to heat treatment.

  Hereinafter, each step will be described. In addition, the raw material used in the manufacturing method of this invention, its content, etc. are as above-mentioned.

Step (1) (Formation of base material layer)
The base material layer can be formed as follows. First, the case where the polyimide which is a typical material of a base material layer is used is demonstrated.

  As described above, in order to give a desired semiconductivity to the base material layer by reacting a tetracarboxylic dianhydride, which is a raw material of polyimide, with a diamine in a solvent such as NMP to form a polyamic acid solution. A conductive agent such as carbon black is added to the polyamic acid solution to prepare a polyamic acid (composition for forming a base layer) in which carbon black is dispersed.

  Centrifugal molding using a rotating drum (cylindrical mold) or the like is performed using the obtained composition for forming a base material layer. In the heating, the inner surface of the drum is gradually heated to reach about 100 to 190 ° C., preferably about 110 to 130 ° C. (first heating stage). The temperature increase rate may be about 1 to 2 ° C./min, for example. The temperature is maintained at the above temperature for 20 minutes to 3 hours, and approximately half or more of the solvent is volatilized to form a self-supporting tubular belt.

In addition, the rotational speed of the rotating drum in the first heating stage is preferably a centrifugal acceleration that is 0.5 to 10 times the gravitational acceleration. In general, the gravitational acceleration (g) is 9.8 (m / s ² ).

  The centrifugal acceleration (G) is derived from the following equation.

G (m / s ² ) = r · ω ² = r · (2 · π · n) ² (I)
(In the formula (I), r is the radius (m) of the cylindrical mold, ω is the angular velocity (rad / s), and n is the number of rotations in one second (the number of rotations in 60 seconds is rpm))

  From the formula (I), the rotation condition of the cylindrical mold can be appropriately set.

  Next, as the second stage heating, the imidization is completed by treatment at a temperature of about 280 to 400 ° C, preferably about 300 to 380 ° C. In this case as well, it is desirable not to reach this temperature all at once from the first stage heating temperature but to gradually increase the temperature to reach that temperature. The second stage heating may be performed while the tubular belt is attached to the inner surface of the rotating drum, or after the first heating stage is finished, the tubular belt is peeled off from the rotating drum, taken out, and separately heated for imidization. You may use for a means and you may heat so that it may become 280-400 degreeC. The time required for this imidation is usually about 20 minutes to 3 hours.

  Similarly, when polyamide imide is used as the material for the base material layer, diamine or diisocyanate derived from diamine and trimellitic acid are reacted in a solvent directly to form polyamide imide, which is then subjected to centrifugal molding to produce a joint. (Seamless) polyamideimide base material layer can be formed.

  When polycarbonate, PVdF, ethylene-tetrafluoroethylene copolymer, polyamide, polyphenylene sulfide, etc. are used as the material for the base material layer, a seamless base material layer is produced by melting and extruding these resins. I can make a film.

  In this way, a seamless base material layer can be formed.

Step (2a) (Formation of surface layer (1))
The surface layer can be formed, for example, as follows.

  The surface layer-forming composition is subjected to centrifugal molding using a cylindrical mold having a surface roughness (Rz) of 0.1 to 1.5 μm. In this case, it is prepared so that the thickness of the obtained surface layer is about 0.5 to 4 μm.

  For example, the surface layer is formed by centrifugal molding of the surface layer in an amount equivalent to obtaining a final thickness on the inner surface of a rotating drum (cylindrical mold) rotated at a centrifugal acceleration of 0.5 to 10 times the acceleration of gravity. After the injection, the rotation speed is gradually increased and the rotation is increased to a centrifugal acceleration of 2 to 20 times the gravitational acceleration, and the entire inner surface is cast by centrifugal force.

  The inner surface of the rotating drum is polished to a predetermined surface accuracy, and the surface state of the rotating drum is almost transferred to the outer surface of the surface layer of the intermediate transfer belt of the present invention. Therefore, the surface roughness of the surface layer can be adjusted to a desired range by controlling the surface roughness of the inner surface of the rotating drum. When the average surface roughness (Rz) of the inner surface of the rotating drum is set in the range of 0.1 to 1.5 μm, a surface layer having a surface roughness (Rz) of 0.1 to 1.5 μm corresponding to the average surface roughness is formed. it can. However, the surface roughness of the surface layer of the intermediate transfer belt is slightly higher than the average surface roughness (Rz) of the inner surface of the rotating drum because fine wrinkles and undulations of the belt are picked up in the measurement. Tend. Therefore, it is possible to employ a rotating drum having a slightly smaller average surface roughness (Rz) of the inner surface relative to the desired surface roughness of the belt surface layer. Note that the roughness of the inner surface of the mold to be used can be arbitrarily controlled by the count of the abrasive paper used when finishing the inner surface.

  The rotating drum is placed on a rotating roller, and is rotated indirectly by the rotation of the roller. The size of the drum can be appropriately selected according to the desired size of the intermediate transfer belt.

  Heating is performed by indirect heating from the outside with a heat source such as a far infrared heater disposed around the drum. The heating temperature may vary depending on the type of the resin, but is usually about (Tm ± 40) ° C., preferably (Tm-40) when the temperature is from room temperature to around the melting point of the resin, for example, the melting point Tm of the resin. ) Gradually raise the temperature to about 0 ° C. to Tm ° C. and heat at the temperature after the temperature increase for about 10 to 60 minutes. As a result, a seamless (seamless) tubular surface layer can be formed on the drum inner surface.

Step (3) (2 layers)
An elastic layer obtained by centrifugal molding of the elastic layer material is formed on the inner surface of the surface layer obtained in the step (2a) to form a two-layer film.

  The above-mentioned elastic layer forming composition is uniformly applied on the inner surface of the surface layer of the rotating drum (cylindrical mold) on which the surface layer is formed, centrifuged, and then heated while rotating the rotating drum. Process. In the heating, the inner surface of the drum is gradually heated to reach about 90 to 180 ° C, preferably about 90 to 110 ° C. The temperature raising rate may be about 1 to 3 ° C./min, for example. It is maintained at the above temperature for 20 minutes to 3 hours, and a two-layer film having a surface layer in the drum and an elastic layer thereon is formed.

Step (4) (Three layers)
The outer surface of the base material layer obtained in the above step (1) and the inner surface of the elastic layer of the two-layer film (surface layer and elastic layer) obtained in the above (3) are superposed and heat-treated.

  Specifically, a known adhesion primer or the like is applied to the inner surface of the two-layered elastic layer formed in the rotating drum, air-dried, and then a base material layer coated with a dry lamination adhesive or the like is inserted on the outer surface and stacked. Match. After the two superimposed layers are pressure-bonded from the inner surface of the belt, the inner surface of the cylindrical mold is gradually heated to reach about 40 to 120 ° C., preferably about 50 to 90 ° C.

  The temperature raising rate may be about 1 to 10 ° C./min, for example. The temperature is maintained at the above temperature for 2 to 30 minutes, and a three-layer belt having a surface layer, an elastic layer and a base material layer in a cylindrical mold is molded.

  The laminated three-layer belt is peeled from the cylindrical mold, and both ends are cut to a desired width to produce a three-layer intermediate transfer belt.

  Moreover, in the said manufacturing method (i), it replaces with said process (3) and (4), the outer surface of a base material layer is piled up on the inner surface of a surface layer, an elastic layer material is inject | poured between both layers, Heat treatment can also be carried out by simultaneously forming the elastic layer and making it into three layers (step (3 ′)).

Step (3 ′) (formation of elastic layer and three layers)
The surface layer and the base material layer separately formed according to the above steps (1) and (2a) are overlapped so that the inner surface of the surface layer and the outer surface of the base material layer are in contact with each other, The elastic layer material is injected by injection. At this time, in order to make the elastic layer uniform, it is preferable to iron from one end of the inner surface of the base material layer to the other end. An intermediate transfer belt can be obtained by heat-treating the obtained laminate. In addition, it is preferable to make it a sealed state between both layers after superimposing both layers.

  For example, when silicone rubber is used as the rubber elastic resin, the laminate obtained by injection is heat-treated at about 110 to 220 ° C., whereby the elastic layer material is vulcanized (crosslinked / cured), and the surface layer and The base material layer is firmly bonded simultaneously.

  In addition, when the rubber elastic resin is urethane rubber, it is preferable to use a mixture of both liquids immediately before film formation.

  Specific examples of the three-layer process will be given.

  A known adhesion primer or the like is uniformly applied to the inner surface of the surface layer formed on the inner surface of the drum and air-dried. A primer is also applied to the outer surface of the formed base material layer, and this is superposed on the inner surface of the surface layer, and O-rings are pressed from the inner side to both ends of the tubular belt in a reduced pressure state, and the superposed surface layer and base material Keep the layers sealed. Next, the elastic layer forming composition is injected into the gap between the two layers by an injection method, and the elastic layer forming composition is uniformly distributed in the circumferential direction using a metal roll from the inner surface side of the base material layer. Cast to be.

  Alternatively, as another embodiment, the following method can be cited.

  A known adhesion primer is uniformly applied to the inner surface of the surface layer formed on the inner surface of the drum. After applying a primer also to the outer surface of the formed base material layer, the primer is placed on the outer surface of the cylindrical core. The core body is inserted into the inner surface of the drum having a surface layer formed on the inner surface, and the core body and the drum are fixed on a concentric shaft. Next, a paste-like elastic layer forming composition is injected from one side of the drum into the gap between the two layers by an injection method. The drum is fixed by sandwiching the left and right sides in the longitudinal direction with a pair of jigs. One jig has an elastic layer material inlet and the other jig has an outlet. Yes.

  The heat treatment after the three layers is gradually heated to 110 to 220 ° C. (for example, a temperature rising rate of about 1 to 3 ° C./min) and treated at that temperature for 0.5 to 4 hours. This completes the crosslinking and curing of the belt. After the heating is completed, the drum is cooled, and the three-layered tubular belt is peeled from the drum inner surface to obtain the intermediate transfer belt of the present invention.

  In addition, although the use of the above-mentioned primer for adhesion is arbitrary, it is preferably used from the viewpoint of improving the adhesive strength. Examples of the adhesion primer include Toray Dow Corning Primer DY39-067.

2.2 Manufacturing method (ii)
The production method (ii) includes the following steps.
(1) A step of forming a base material layer by centrifugal molding or melt extrusion molding of a resin,
(2b) A mixed solution obtained by dissolving or swelling a fluororesin in an organic solvent is subjected to centrifugal molding using a cylindrical mold having a surface roughness (Rz) of 0.1 to 1.5 μm, and the thickness is Forming a surface layer of 0.5 to 4 μm,
(2c) A step of holding the surface layer obtained in (2b) above for 25 hours or more at a temperature not lower than the glass transition point of the fluororesin and not higher than the melting point,
(3) A step of forming an elastic layer having a thickness of 50 μm or more on the inner surface of the surface layer obtained in (2c) above by centrifugal molding to form a two-layer film, and (4) above ( A step of superposing the outer surface of the base material layer obtained in 1) and the inner surface of the elastic layer of the two-layer film obtained in (3) above, and subjecting to heat treatment.

  Hereinafter, although each process is demonstrated, the raw material to be used, its content, etc. are as above-mentioned similarly to the case of the above-mentioned manufacturing method (i).

Step (1) (Formation of base material layer)
It is the same as that of the manufacturing method (i).

Steps (2b) and (2c) (Formation of surface layer (2))
Using a rotating drum, a mixed solution (surface layer forming composition (i) or (ii)) obtained by dissolving or swelling a fluororesin in an organic solvent is used in the same manner as in step (2a). A surface layer is formed on the inner surface. Thereafter, the rotating drum having a surface layer formed on the inner surface is put into an electric oven, and the temperature is not lower than the glass transition point of the fluororesin and not higher than the melting point (preferably 2 to 3 ° C. lower than the melting point of the fluororesin) for 25 hours or longer. Hold. Thereby, a fluororesin surface layer having the same crystal structure as in the step (2a) can be produced. As the holding temperature condition or the like, the above-described condition or the like can be used.

  When the surface layer is produced through the steps (2b) and (2c), if the centrifugal molding is performed at a temperature close to the melting point of the fluororesin surface layer, the crystal structure returns from the β or γ type to the α type again. Therefore, it is preferable that the temperature at which the elastic layer is centrifugally molded is lower than the melting point of the fluororesin (around 100 ° C.).

Step (3) (4) (two layers)
Except for using the surface layer obtained in steps (2b) and (2c), this is the same as steps (3) and (4) of production method (i).

  Further, similarly to the manufacturing method (i), after forming the surface layer and the base material layer by the above (1) and (2c), the outer surface of the base material layer is superimposed on the inner surface of the surface layer, It can also be produced by injecting a composition for forming an elastic layer in between and heat-treating it (step (3 ′)). About this method, the method similar to the above-mentioned manufacturing method (i) can be mentioned.

  Hereinafter, although a test example etc. are shown and this invention is demonstrated in detail, this invention is not limited to these.

  The evaluation of each layer was performed as follows.

<Base layer solid content concentration>
The sample is precisely weighed in a heat-resistant container such as a metal cup, and the weight of the sample at this time is Ag. The heat-resistant container containing the sample is placed in an electric oven and heated and dried while sequentially heating at 120 ° C. × 12 minutes, 180 ° C. × 12 minutes, 260 ° C. × 30 minutes, and 300 ° C. × 30 minutes. The weight of the solid content (solid content weight) is defined as Bg. The values of A and B of five samples for the same sample were measured (n = 5) and applied to the following formula (II) to obtain the solid content concentration. The average value of the five samples was adopted as the solid content concentration.

<Elastic layer solid content concentration>
The sample is precisely weighed in a heat-resistant container such as a metal cup, and the weight of the sample at this time is defined as A′g. Put the heat-resistant container containing the sample in an electric oven, heat and dry while heating up in order of 60 ℃ × 12min, 90 ℃ × 12min, 120 ℃ × 30min, and 150 ℃ × 30min. Let B′g be the weight of the solid content (solid content weight). The values of A ′ and B ′ of five samples of the same sample were measured (n = 5) and applied to the following formula (III) to determine the solid content concentration. The average value of the five samples was adopted as the solid content concentration.

<Thickness>
The thickness and total thickness of each layer were measured as a mean value by measuring a total of 24 points of 3 points in the width direction and 8 points in the circumferential direction by using a flat type probe of a Digimatic indicator manufactured by Mitsuyo Corporation.

  In addition, the thickness of each layer after making the multilayer belt is 8 points at the same pitch in the circumferential direction after cutting into the product part width, collecting a total of 16 points, and embedding them with epoxy resin, The cross section produced using the microtome was observed with an electron microscope, and the thickness of each layer was measured. Discrimination of the interface of each layer was performed based on the total absorbance image based on the ATR image of Fourier transform infrared spectroscopy.

<Surface roughness>
The surface roughness (μm) was measured according to JIS B0601-1982. As a measuring instrument, Surfcom 575A manufactured by Tokyo Seimitsu Co., Ltd. was used. The measurement conditions were CUTOFF 0.25, measurement length 2.5 mm, and T-SPEED 0.06 mm / s. Five different surface portions were measured in the same belt, and the average value of the ten-point average roughness (Rz) was defined as the surface roughness.

<Static friction coefficient>
The static friction coefficient was measured using 10 different surface parts in the same belt using Heidon 94i manufactured by Shinto Kagaku Co., Ltd., and the average value was taken as the static friction coefficient.

<Surface resistivity, volume resistivity>
The surface resistivity (Ω / □) and the volume resistivity (Ω · cm) were measured using a resistance measuring instrument “HIRESTA IP / HR Blob” manufactured by Mitsubishi Chemical Corporation. A belt cut to a length of 360 mm in the width direction is used as a sample, and the surface resistivity is measured at an applied voltage of 100 V for 10 seconds at a total of 12 locations, 3 locations at the same pitch in the width direction and 4 locations in the longitudinal (circumferential) direction. The volume resistivity was measured and indicated by the average value.

<Rubber hardness>
In accordance with JIS K6253, using a durometer A, a bulk (lump) having a thickness of 10 mm was prepared and evaluated using the material constituting the elastic layer.

<XRD analysis>
The apparatus used Rigaku RINT2500VHF (Cu, 200mA, 45kV), and measured on condition of the following.
Sampling step: 0.02 °
Scan speed: 1 ° / 4.0s

<IR analysis>
The apparatus measured the surface layer by the ATR method (total reflection measurement method) using a Fourier transform infrared spectroscopic analyzer (Spectrum 100, manufactured by Perkin Elmer). A diamond prism was used as the prism, and the number of spectrum accumulations was 10. The measurement range was 650 to 4000 cm ⁻¹ .

The obtained IR spectrum was corrected using a baseline correction command (automatic smoothing) of (software name Spectrum (version 6.1.0.0038), manufactured by Perkin Elmer). Peak height near 760 cm ⁻¹ (derived from α-type crystal) when the height from the base line of 870 cm ⁻¹ peak (derived from C—F bond) peak that can be confirmed by IR spectrum of the fluororesin surface layer is 1.0 )

Example 1
(1) Film formation of base material layer Under nitrogen flow, 47.6 g of 4,4′-diaminodiphenyl ether (ODA) is added to 488 g of N-methyl-2-pyrrolidone, and kept at 50 ° C. and stirred to completely dissolve. I let you. To this solution, 70 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was gradually added to obtain 605.6 g of a polyamic acid solution. This polyamic acid solution had a number average molecular weight of 18,000, a viscosity of 37 poise, and a solid content concentration of 18.2% by weight.

  Next, 21 g of acidic carbon black (pH 3.0) and 80 g of N-methyl-2-pyrrolidone are added to 450 g of this polyamic acid solution, and carbon black (CB) is uniformly dispersed with a ball mill to form a base material layer. A composition was obtained. This master batch solution had a solid concentration of 18.7% by weight and a CB concentration in the solid content of 20.4% by weight.

  273 g was collected from the obtained base layer forming composition, poured into a rotating drum, and molded under the following conditions.

  Rotating drum: An internal mirror-finished metal drum having an inner diameter of 301.5 mm and a width of 540 mm was placed on two rotating rollers and arranged to rotate with the rotation of the rollers (see, for example, FIG. 2).

  Heating temperature: A far-infrared heater was disposed on the outer surface of the drum so that the inner surface temperature of the drum was controlled at 120 ° C.

  First, 273 g of the substrate layer forming composition was uniformly applied to the inner surface of the drum while the rotating drum was rotated, and heating was started. The heating was performed at a temperature of 1 ° C./min up to 120 ° C., and the heating was continued for 60 minutes while maintaining the rotation.

After completion of the rotation and heating, the rotating drum was removed as it was without cooling, and was left in a hot-air residence type oven to start heating for imidization. This heating also reached 320 ° C. while gradually raising the temperature. And after heating for 30 minutes at this temperature, it cooled to normal temperature, peeled and took out the semiconductive tubular polyimide belt formed in this drum inner surface. The belt had a thickness of 80 μm, an outer peripheral length of 944.3 mm, a surface resistivity of 2 × 10 ^{11 to} 5 × 10 ¹¹ Ω / □, and a volume resistivity of 2 × 10 ⁹ to 4 × 10 ⁹ Ω · cm.

(2) Film formation of surface layer 100 g of VdF-HFP copolymer resin (Kyner # 2801, Arkema 11 mol%), which is a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), as the surface layer. Was dissolved in 900 g of N, N-dimethylacetamide (DMAc) to prepare a solution A having a solid content concentration of 10% by weight.

  100 g of organically modified montmorillonite (Lucentite SEN, manufactured by Coop Chemical Co., Ltd .: expressed as SEN in Table 1) is added to 900 g of dimethylacetamide, and uniformly dispersed by a ball mill to obtain a solution B having a solid content concentration of 10% by weight. Prepared.

  Solution A and Solution B were mixed with a paint shaker at A: B = 99.8: 0.2 (weight ratio), the solid content concentration was 10% by weight, and the organically modified montmorillonite concentration in the solid content was 0.2% by weight. A solution was obtained. This was diluted with a mixed solvent of DMAc: butyl acetate = 1: 2, the solid content concentration was 2.5% by weight, and the organically modified montmorillonite concentration in the solid content was 0.2% by weight (the mixing ratio of montmorillonite relative to the total weight of the surface layer). (A composition for forming a surface layer). 119 g of this solution was formed into a film under the following conditions.

  Rotating drum: A metal drum having an inner diameter of 301.0 mm, a width of 540 mm, and an inner surface 10-point average roughness (Rz) = 0.3 μm is placed on two rotating rollers, and is arranged so as to rotate with the rotation of the rollers. (See, for example, FIG. 2).

  With the rotating drum rotated, the surface layer forming composition was uniformly applied to the drum inner surface and heating was started. Heating was performed at a rate of 2 ° C./min up to 130 ° C., and heating was continued for 20 minutes while maintaining the rotation. After forming a surface layer on the inner surface of the drum, the drum was cooled to room temperature. The thickness of the surface layer formed on the inner surface of the drum was measured with an eddy current thickness gauge (manufactured by Kett Science Laboratory Co., Ltd.) and found to be 3 μm.

In addition, using the above-mentioned composition for forming a surface layer, a surface layer of 10 μm was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 4 × 10 ^{12 to} 6 × 10 ¹² Ω · cm.

(3) Film formation of elastic layer 300 g of acidic carbon black (pH 3.5) was added to a solution of 1000 g of polyurethane elastomer (Urehyper RUP1627, manufactured by Dainippon Ink Co., Ltd.) dissolved in 1300 g of toluene, and uniformly dispersed with a ball mill. Went. The solid content concentration of the master batch solution thus obtained was 50% by weight, and the carbon black (CB) concentration in the solid content was 23% by weight. 11.04 g (manufactured by Dainippon Ink Co., Ltd.) of the curing agent CLH-5 was added to 257 g of this master batch and stirred to obtain a carbon black dispersed resin solution (composition for forming an elastic layer).

  The elastic layer forming composition was uniformly applied to the inner surface of the surface layer previously formed in a rotated state, and heating was started. The heating was performed at a rate of 2 ° C./min up to 150 ° C., and the heating was continued for 30 minutes while maintaining the rotation, thereby forming a rubber elastic layer on the inner surface of the drum. The rubber elastic layer had a thickness of 253 μm.

  As a preliminary test, when the rubber hardness of the urethane rubber single film produced with this elastic layer forming composition was measured, the type A hardness (JIS K6253) was 40 °.

(4) Lamination of inner surface of rubber elastic layer and outer surface of polyimide The primer DY39-067 (manufactured by Toray Dow Corning Co., Ltd.) was applied to the inner surface of the rubber elastic layer formed in (3) above, air-dried, and then the dry lamination adhesive was thinned. The polyimide belt (1) applied on the outer surface was inserted and overlapped. Pressure bonding was performed from the inner surface of the base material layer, and heating (80 to 100 ° C.) was performed to complete the bonding. The laminated multilayer belt was peeled off from the mold, both ends were cut, and a multilayer belt having a width of 360 mm was collected.

The multilayer belt has a thickness of 334 μm, a coefficient of static friction of 0.60, an outer peripheral length of 945.0 mm, a surface resistivity of 2 × 10 ¹¹ to 4 × 10 ¹¹ Ω / □, and a volume resistivity of 4 × 10 ^{10 to} 7 × 10 ¹⁰ Ω. cm and the surface roughness (Rz) were 0.5.

Example 2
A multilayer belt was produced in the same manner as in Example 1 except that the blending ratio of the layered clay mineral was changed to 3.0% by weight. The multilayer belt has a thickness of 333 μm, a coefficient of static friction of 0.53, a surface resistivity of 2 × 10 ^{11 to} 6 × 10 ¹¹ Ω / □, a volume resistivity of 5 × 10 ^{10 to} 9 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the composition for forming a surface layer prepared in Example 2, a surface layer of 10 μm was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 1 × 10 ¹² to 2 × 10 ¹² Ω · cm.

Example 3
A multilayer belt was produced in the same manner as in Example 1 except that the blending ratio of the layered clay mineral was 1.0% by weight and the thickness of the surface layer was 1 μm. The multilayer belt has a thickness of 335 μm, a coefficient of static friction of 0.57, a surface resistivity of 4 × 10 ^{11 to} 7 × 10 ¹¹ Ω / □, a volume resistivity of 7 × 10 ^{10 to} 9 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the surface layer forming composition prepared in Example 3, a surface layer of 10 μm was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 3 × 10 ^{12 to} 5 × 10 ¹² Ω · cm.

Example 4
A multilayer belt was produced in the same manner as in Example 3 except that the thickness of the surface layer was 4 μm. The multilayer belt has a thickness of 336 μm, a coefficient of static friction of 0.55, a surface resistivity of 1 × 10 ¹¹ to 4 × 10 ¹¹ Ω / □, a volume resistivity of 2 × 10 ^{10 to} 5 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the composition for surface layer formation produced in Example 4, the surface layer of 10 micrometers separately was produced on the same film forming conditions. The volume resistance value of the 10 μm surface layer was 4 × 10 ^{12 to} 5 × 10 ¹² Ω · cm.

Example 5
A multilayer belt was produced in the same manner as in Example 1 except that the blending ratio of the layered clay mineral was 1.0% by weight and the rubber hardness was type A hardness (JIS K6253) 55 °. The multilayer belt has a thickness of 332 μm, a coefficient of static friction of 0.53, a surface resistance of 1 × 10 ¹¹ to 2 × 10 ¹¹ Ω / □, a volume resistivity of 2 × 10 ¹⁰ to 4 × 10 ¹⁰ Ω · cm, and a surface roughness (Rz ) Was 0.5.

In addition, using the surface layer forming composition prepared in Example 5, a 10 μm surface layer was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 2 × 10 ^{12 to} 5 × 10 ¹² Ω · cm.

Example 6
(1) Film formation of a base material layer The same base material layer as Example 1 was formed into a film.

(2) Film formation of surface layer 100 g of VdF-HFP copolymer resin (Kyner # 2801, Arkema 11 mol%), which is a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), as the surface layer. Was dissolved in 900 g of N, N-dimethylacetamide (DMAc) to prepare a solution B having a solid concentration of 10% by weight.

  Solution B was diluted with a mixed solvent of DMAc: butyl acetate = 1: 2 to prepare a solution (surface layer forming composition) having a solid content concentration of 2.5% by weight. 119 g of this solution was formed into a film under the following conditions.

  Rotating drum: A metal drum having an inner diameter of 301.0 mm, a width of 540 mm, and an inner surface 10-point average roughness (Rz) = 0.3 μm is placed on two rotating rollers, and is arranged so as to rotate with the rotation of the rollers. (See, for example, FIG. 2).

  With the rotating drum rotated, the surface layer forming composition was uniformly applied to the drum inner surface and heating was started. The heating was performed at 2 ° C./min up to 130 ° C., and the film was heated to form a film while maintaining its rotation for 20 minutes. Thereafter, the surface layer fixed to the mold was held in an oven set at 150 ° C. for 25 hours to form a surface layer on the drum inner surface (the melting point of Kyner # 2801 is 140 to 145 ° C. The oven temperature was set to 150 ° C. so that the drum temperature was 140 ° C.). Thereafter, the drum was cooled to room temperature. The thickness of the surface layer formed on the inner surface of the drum was measured with an eddy current thickness gauge (manufactured by Kett Science Laboratory Co., Ltd.) and found to be 3 μm.

In addition, using the above-mentioned composition for forming a surface layer, a surface layer of 10 μm was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 9 × 10 ¹² to 2 × 10 ¹³ Ω · cm.

(3) Film formation of elastic layer 300 g of acidic carbon black (pH 3.5) was added to a solution of 1000 g of polyurethane elastomer (Urehyper RUP1627, manufactured by Dainippon Ink Co., Ltd.) dissolved in 1300 g of toluene, and uniformly dispersed with a ball mill. Went. The solid content concentration of the master batch solution thus obtained was 50% by weight, and the carbon black (CB) concentration in the solid content was 23% by weight. 11.04 g (manufactured by Dainippon Ink Co., Ltd.) of the curing agent CLH-5 was added to 257 g of this master batch and stirred to obtain a carbon black dispersed resin solution (composition for forming an elastic layer).

  The elastic layer forming composition was uniformly applied to the inner surface of the surface layer previously formed in a rotated state, and heating was started. The heating was performed at a rate of 2 ° C./min up to 100 ° C., and the heating was continued for 30 minutes while maintaining the rotation, thereby forming a rubber elastic layer on the inner surface of the drum. The rubber elastic layer had a thickness of 253 μm.

  As a preliminary test, when the rubber hardness of the urethane rubber single film produced with this elastic layer forming composition was measured, the type A hardness (JIS K6253) was 40 °.

(4) Lamination of inner surface of rubber elastic layer and outer surface of polyimide The primer DY39-067 (manufactured by Toray Dow Corning Co., Ltd.) was applied to the inner surface of the rubber elastic layer formed in (3) above, air-dried, and then the dry lamination adhesive was thinned. The polyimide belt (1) applied on the outer surface was inserted and overlapped. Pressure bonding was performed from the inner surface of the base material layer, and heating (80 to 100 ° C.) was performed to complete the bonding. The laminated multilayer belt was peeled off from the mold, both ends were cut, and a multilayer belt having a width of 360 mm was collected. The multilayer belt has a thickness of 329 μm, a coefficient of static friction of 0.55, a surface resistivity of 5 × 10 ^{11 to} 6 × 10 ¹¹ Ω / □, a volume resistivity of 5 × 10 ^{10 to} 7 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

Example 7
A multilayer belt was produced in the same manner as in Example 6 except that the holding time in the oven was 30 hours. The multilayer belt has a thickness of 330 μm, a coefficient of static friction of 0.56, a surface resistivity of 6 × 10 ¹¹ to 8 × 10 ¹¹ Ω / □, a volume resistivity of 5 × 10 ¹⁰ to 8 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the surface layer forming composition prepared in Example 7, a surface layer of 10 μm was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 8 × 10 ¹² to 1 × 10 ¹³ Ω · cm.

Example 8
A multilayer belt was produced in the same manner as in Example 6 except that the holding time in the oven was 48 hours. The multilayer belt has a thickness of 332 μm, a coefficient of static friction of 0.58, a surface resistivity of 3 × 10 ¹¹ to 4 × 10 ¹¹ Ω / □, a volume resistivity of 4 × 10 ^{10 to} 6 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the surface layer forming composition prepared in Example 8, a 10 μm surface layer was separately prepared under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 8 × 10 ^{12 to} 9 × 10 ¹² Ω · cm.

Comparative Example 1
A multilayer belt was produced according to the same method as in Example 1 without blending the layered clay mineral in the surface layer. The multilayer belt has a thickness of 330 μm, a coefficient of static friction of 0.75, a surface resistivity of 6 × 10 ^{11 to} 9 × 10 ¹¹ Ω / □, a volume resistivity of 5 × 10 ¹⁰ to 8 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the composition for surface layer formation produced in the comparative example 1, the surface layer of 10 micrometers was produced separately on the same film forming conditions. The volume resistance value of the 10 μm surface layer was 1 × 10 ¹³ to 4 × 10 ¹³ Ω · cm.

Comparative Example 2
A multilayer belt was produced in the same manner as in Example 3 except that the thickness of the surface layer was 6.0 μm. The multilayer belt has a thickness of 332 μm, a coefficient of static friction of 0.56, a surface resistivity of 4 × 10 ^{11 to} 5 × 10 ¹¹ Ω / □, a volume resistivity of 3 × 10 ^{10 to} 5 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the composition for surface layer formation produced in the comparative example 2, the surface layer of 10 micrometers was produced separately on the same film forming conditions. The volume resistance value of the 10 μm surface layer was 3 × 10 ^{12 to} 6 × 10 ¹² Ω · cm.

Comparative Example 3
A multilayer belt was produced in the same manner as in Example 3 except that the thickness of the surface layer was 0.2 μm. The multilayer belt has a thickness of 335 μm, a coefficient of static friction of 0.65, a surface resistivity of 3 × 10 ^{11 to} 7 × 10 ¹¹ Ω / □, a volume resistivity of 6 × 10 ¹⁰ to 8 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the composition for surface layer formation produced in the comparative example 3, the surface layer of 10 micrometers separately was produced on the same film forming conditions. The volume resistance value of the 10 μm surface layer was 4 × 10 ^{12 to} 6 × 10 ¹² Ω · cm.

Comparative Example 4
A multilayer belt was produced in the same manner as in Example 6 except that the holding time in the oven was 12 hours. The multilayer belt has a thickness of 333 μm, a coefficient of static friction of 0.72, a surface resistivity of 6 × 10 ^{11 to} 9 × 10 ¹¹ Ω / □, a volume resistivity of 7 × 10 ^{10 to} 9 × 10 ¹⁰ Ω · cm, and a surface roughness ( Rz) was 0.5.

In addition, using the composition for surface layer formation produced in the comparative example 4, the surface layer of 10 micrometers was produced separately on the same film forming conditions. The volume resistance value of the 10 μm surface layer was 2 × 10 ¹³ to 4 × 10 ¹³ Ω · cm.

Comparative Example 5
A multilayer belt was produced in the same manner as in Example 7 except that the holding time in the oven was 24 hours. The multilayer belt has a thickness of 334 μm, a coefficient of static friction of 0.65, a surface resistivity of 1 × 10 ^{11 to} 5 × 10 ¹¹ Ω / □, a volume resistivity of 2 × 10 ^{10 to} 5 × 10 ¹⁰ Ω · cm, a surface roughness ( Rz) was 0.5.

In addition, using the composition for surface layer formation produced in the comparative example 5, the surface layer of 10 micrometers separately was produced on the same film forming conditions. The volume resistance value of the 10 μm surface layer was 2 × 10 ^{13 to} 5 × 10 ¹³ Ω · cm.

  The following evaluations were performed on the intermediate transfer belts obtained in the above examples and comparative examples. The evaluation results are shown in Table 1.

<Primary and secondary transfer efficiency>
The primary transfer efficiency was determined from the following equation by measuring the toner weight on the photoreceptor before and after transfer. The secondary transfer efficiency was determined from the following equation by measuring the toner weight on the transfer belt before and after transfer.

Each transfer efficiency was evaluated according to the following criteria.
(Primary transfer efficiency)
○: higher than 97% △: 95-97%
×: Less than 95% (secondary transfer efficiency)
○: higher than 97% △: 95-97%
X: Less than 95%

<Line dropout>
Line dropout (primary transfer efficiency) was determined from the above transfer efficiency equation by measuring the weight of toner on the photoreceptor before and after transfer in an image of only a line image. Line breakage was evaluated according to the following criteria.
○: higher than 90% △: 85-90%
X: Less than 85%

<Rough paper transfer>
Using a Strathmore writing raid made by Strathmore with an unevenness of about 50 μm, solid printing was performed with magenta, and the toner on the deepest portion (concave portion) was visually determined. The evaluation criteria are as follows.
◎: Completely uniform transfer ○: Slightly light △: Slightly missing white ×: No toner on white

<Filming>
In filming, the degree of adhesion of the toner to the intermediate transfer belt after printing 1000 sheets was visually evaluated. The evaluation criteria are as follows.
○: No sticking △: Slight sticking is recognized ×: Clearly sticking

<Taber wear amount>
The Taber abrasion amount was evaluated according to JIS K-7204. The wear wheel of the Taber abrasion tester was performed 300 times with CS-17 and a load of 250 g (number of samples = 8 each). The smaller the Taber wear value, the higher the durability (abrasion resistance) of the intermediate transfer belt.

<Mitt test>
The apparatus used was MIT-SA manufactured by Toyo Seiki Co., Ltd. The conditions were load: 0.25 kgf, repetition rate: 90 cpm, bending angle: 45 °, chuck tip radius: 0.38 mm, and the number of bendings was 2000. Sample pieces were prepared so as to be bent with respect to the circumferential direction of the belt at the time of the test, and evaluated using the sample pieces. This test is a test for examining the flexibility (how strong against bending) of a rubber elastic belt. The sample after the test was visually observed and evaluated according to the following evaluation criteria.
○: Slightly scratched △: Clearly scratched ×: Large cracks were confirmed

<Removal of surface layer after endurance of paper>
After copying paper is wound around the outer surface of the secondary transfer roll of the copying machine, a pseudo continuous feed is made, and after a driving test equivalent to 100,000 sheets of A4 paper, the presence or absence of peeling of the transfer belt surface layer is visually observed. confirmed.

  From the results shown in Table 1, in Comparative Example 1 in which the layered clay mineral was not added, the amount of Taber abrasion increased compared to Example 1 in which the layered clay mineral was added, and peeling of the surface layer was observed. Further, as is clear from the comparison between Examples 6 to 8 and Comparative Examples 4 and 5, it can be seen that in the present invention, the amount of Taber wear is reduced and there is no peeling of the surface layer.

  Further, as is apparent from Comparative Example 2 (surface layer thickness: 6.0 μm) and Comparative Example 3 (surface layer thickness: 0.2 μm), the surface layer thickness is in the range of 0.5 to 4 μm. If this is removed, the amount of Taber wear increases. In Comparative Example 2, the belt bendability was poor from the results of the mitt test, and in Comparative Example 3, defects such as pinholes were likely to occur and filming occurred.

The IR measurement results of the surface layers of Example 2 and Comparative Example 1 are shown in FIG. Peak derived from the crystalline structure of the α type in the vicinity of 760 cm ^-1 and around 790 cm ^-1 is a fluorine resin surface layer of Comparative Example 1 can be confirmed. On the other hand, in the fluororesin to which the layered clay mineral of Example 2 was added, these peaks disappeared, and β, around 770 cm ⁻¹ (γ type), 810 cm ⁻¹ (γ type), and 830 cm ⁻¹ (β and γ type), A peak derived from the γ type can be confirmed, and the addition of the layered clay mineral suggests that the crystal structure of the fluororesin surface layer has undergone a phase transition from the α type to the β or γ type.

The IR measurement results of the surface layer of Example 8 and Comparative Examples 1, 4, and 5 are shown in FIG. Peak derived from α-type over time (760 cm around ^-1 and near 790 cm ^-1) gradually decreases, beta type or gamma-type-derived peak (770 cm ^-1 (gamma type), 810 cm ^-1 (gamma type) , 830 cm ⁻¹ (β and γ type) can be confirmed. From this result, it was confirmed that the proportion of the α-type crystal structure of the fluororesin surface layer gradually decreased and the proportion of the β-type or γ-type crystal structure increased as the holding time became longer. Further, the spectrum for 48 hours is the same as the spectrum when the layered clay mineral of FIG. 4 is added, and it can be confirmed that a β- or γ-type crystal structure is shown.

Moreover, the peak height (derived from α-type crystal) in the vicinity of 760 cm ⁻¹ of the surface layers of Examples 1 to 3, 6 to 8 and Comparative Examples 1, 4, and 5 is shown in FIG. Comparative Example 1 (holding time: 0 hour), Comparative Example 4 (holding time: 12 hours), Comparative Example 5 (holding time: 24 hours), Example 6 (holding time: 25 hours), Example 7 (holding time) : 30 hours), the order of Example 8 (retention time: 48 hours), that is, the height of the peak derived from the α-type crystal decreases with time. Moreover, the 25-hour holding product and the 30-hour holding product showed almost the same value in the layered clay mineral additive (Examples 1 to 3) and the physical property test results (abrasion resistance, mitt test, etc.). From this result, it can be seen that when the peak height in the vicinity of 760 cm ⁻¹ is 0.2 or less, the phase transition is almost to the β-type or γ-type crystal structure.

  From the above results, layered clay mineral was added to the surface layer in a predetermined amount, or the fluororesin was held at a temperature not lower than the glass transition point and not higher than the melting point for 25 hours or more, so that the crystal structure of the surface layer was transformed into β type or γ type I was able to confirm. Furthermore, the phase transition of the crystal structure of the fluororesin surface layer improved the abrasion resistance (durability) of the rubber elastic belt from the Taber abrasion amount and the mitt test results of Examples 7 and 8 and Comparative Examples 4 and 5. Is suggested.

Claims (10)

Intermediate transfer belt for image forming apparatus comprising at least the following three layers:
(A) a resin base layer;
(B) an elastic layer containing a rubber elastic resin, and (c) a surface layer containing a fluororesin, and in the spectrum obtained by measuring the surface layer by infrared spectroscopy (IR), it is around 870 cm ⁻¹ . peak height around 760 cm ^-1 becomes 0.2 or less when the height from the base line of the peak can be confirmed was 1, the thickness of the surface layer is Ri 1 ～4Myuemu der,
The fluororesin is polyvinylidene fluoride (PVDF), a copolymer resin of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), or a mixture thereof . The intermediate transfer belt for an image forming apparatus according to claim 1, wherein the surface layer contains 0.1 to 5 wt% of layered clay mineral. The intermediate transfer belt for an image forming apparatus according to claim 2 , wherein the layered clay mineral is an organically modified layered clay mineral. The intermediate transfer belt for an image forming apparatus according to claim 2 or 3 , wherein the surface layer is obtained by coating and drying a mixed solution obtained by dissolving or swelling a fluororesin and a layered clay mineral in an organic solvent. The intermediate transfer belt for an image forming apparatus according to claim 4 , wherein the organic solvent is an aprotic polar solvent or a mixed organic solvent of an aprotic organic solvent and another organic solvent. Wherein the aprotic polar solvent is, N, N- dimethylacetamide, N, N- dimethylformamide, at least one selected from the group consisting of dimethyl sulfoxide and N-methyl-2-pyrrolidone, to claim 5 The intermediate transfer belt for an image forming apparatus as described. 2. The intermediate transfer belt for an image forming apparatus according to claim 1, wherein the surface layer is obtained after film formation by being held for 25 hours or more at a temperature not lower than the glass transition point of the fluororesin and not higher than the melting point. The intermediate transfer belt for an image forming apparatus according to any one of claims 1 to 7 , wherein the surface layer has a volume resistivity of 10 ¹² Ω · cm or more and a static friction coefficient of 0.1 to 1. The type A hardness of the rubber elastic layer is 30 to 80 °, the intermediate transfer belt for an image forming apparatus according to any one of claims 1-8 that has a thickness of 100 to 300 [mu] m. Said surface layer, an image forming apparatus for the intermediate transfer belt according to any one of claims 1 to 9, formed by a film by a centrifugal molding method.

Images