JP4990335B2 - 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, or a facsimile.

  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). It is known that it is effective to make such a surface layer as thin as possible in order to obtain a high-quality image, and various intermediate transfer belts having a thin surface layer have been studied.

  However, since the intermediate transfer belt for an image forming apparatus receives external force from a sliding member that contacts the belt surface such as paper, a cleaning blade, or a roll, when the surface layer is a thin film, the stress applied to the belt is reduced. There is a problem that cracking or peeling of the surface layer occurs due to concentration on the surface layer. Further, in order to solve such problems, when the hardness of the entire belt is increased, there is a problem that although the durability is excellent, the image quality is deteriorated.

  In order to solve such a problem, the present inventors are an intermediate transfer belt for an image forming apparatus comprising a base material layer, a rubber elastic layer, and a surface layer, and only a portion that contacts the surface layer of the rubber elastic layer. Developed a belt with increased rubber hardness. By using the belt having such a configuration, it is possible to avoid stress concentration on the surface layer and achieve excellent durability while maintaining a high-quality image. However, in this technique, a filler may be added in order to increase the rubber hardness of only the portion in contact with the surface layer. However, depending on the type of the filler, it is said that white spots and density reduction occur when evaluated with a halftone image. An image defect may occur, which is not sufficient.

Japanese Patent No. 3248455

  The present invention has been made in view of the above-mentioned problems, and a main object of the present invention is to provide an intermediate transfer belt for an image forming apparatus having excellent durability against external friction while maintaining a high-quality image. And

The inventors of the present invention are an intermediate transfer belt for an image forming apparatus that is laminated in the order of a resin base layer, a rubber elastic layer, and a surface layer, and includes at least the three layers, and the rubber elastic layer has an average particle diameter. Is added to a particulate or spherical filler of 0.4 to 8 μm, and the mass concentration M of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to a depth of 20 μm toward the base material layer side. ₁ and the ratio (M ₁ / M ₃ ) of the mass concentration M ₃ of the filler contained in the region having a depth of 120 to 140 μm from the interface between the surface layer and the rubber elastic layer toward the base material layer side is 1.3 or more It was found that by using the intermediate transfer belt for image formation as described above, durability against external friction and the like was excellent while maintaining a high-quality image. In addition, since the intermediate transfer belt of the present invention can make the surface layer thin, the followability to the unevenness of the paper 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. (A) a resin base layer;
(B) a rubber or elastomer rubber elastic layer having a thickness of 200 to 400 μm;
(C) a resin surface layer having a thickness of 0.5 to 6 μm;
An intermediate transfer belt for an image forming apparatus including at least the three layers,
A particulate or spherical filler having an average particle diameter of 0.4 to 8 μm is added to the rubber elastic layer,
A mass concentration M ₁ of filler contained in the region from the interface of the surface layer and the rubber elastic layer to a depth 20μm towards the base layer side, toward the interface between the surface layer and the rubber elastic layer on the substrate layer side An intermediate transfer belt for image formation in which a ratio (M ₁ / M ₃ ) of mass concentration M ₃ of fillers contained in a region having a depth of 120 to 140 μm is 1.3 or more.
Item 2. The intermediate transfer belt for image formation according to Item 1, wherein the filler has an average particle diameter of 0.4 to 5 μm.
Item 3. Item 1 or 2 above, wherein the amount of filler added to the rubber elastic layer is 0.4% or more by volume fraction, and the IRHD hardness (JIS K6253) measured from the surface layer side is 82 IRHD or less. An intermediate transfer belt for image formation as described in 1.
Item 4. Item 4. The intermediate transfer belt for image formation according to any one of Items 1 to 3, wherein the rubber elastic layer is formed by a centrifugal molding method.
Item 5. Item 5. The intermediate transfer belt for image formation according to Item 4, wherein the rotational speed in the centrifugal molding method is a centrifugal acceleration that is twice or more the gravitational acceleration (9.8 m / s ² ).

  The intermediate transfer belt for an image forming apparatus of the present invention has a rubber hardness only at a portion in contact with the surface layer of the rubber elastic layer by adding a particulate or spherical filler having an average particle diameter of 0.4 to 8 μm to the rubber elastic layer. It has been found that durability against external friction and the like is excellent while maintaining a high-quality image.

  Therefore, since the intermediate transfer belt for an image forming apparatus of the present invention is excellent in durability while maintaining a high quality image, an electrophotographic system such as a copying machine (including a color copying machine), a printer, a facsimile machine or the like is used. It can be suitably used as an intermediate transfer belt of the employed image forming apparatus. The intermediate transfer belt of the present invention can form a good halftone image.

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 a figure which shows the major axis and minor axis in the case of an aspect-ratio measurement. It is a schematic diagram of a belt cross section. 2 is a cross-sectional SEM photograph of the multilayer belt of Example 1.

1. Intermediate transfer belt for image forming apparatus The intermediate transfer belt for image forming apparatus of the present invention is:
(A) a resin base layer;
(B) a rubber or elastomer rubber elastic layer having a thickness of 200 to 400 μm;
(C) a resin surface layer having a thickness of 0.5 to 6 μm;
An intermediate transfer belt for an image forming apparatus including at least the three layers,
A particulate or spherical filler having an average particle diameter of 0.4 to 8 μm is added to the rubber elastic layer,
A mass concentration M ₁ of filler contained in the region from the interface of the surface layer and the rubber elastic layer to a depth 20μm towards the base layer side, toward the interface between the surface layer and the rubber elastic layer on the substrate layer side The ratio (M ₁ / M ₃ ) of the mass concentration M ₃ of the filler contained in the region having a depth of 120 to 140 μm is 1.3 or more.

  Hereinafter, each layer of the intermediate transfer belt of the present invention will be described in detail.

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.

  As said diisocyanate, the compound etc. which the amino group in the above-mentioned diamine component substituted by the isocyanate group are mentioned.

  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, 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) Rubber elastic layer The elastic layer in the intermediate transfer belt according to 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. It is done. The rubber elastic layer is formed of an elastic layer forming composition containing rubber or elastomer (hereinafter also referred to as rubber material). The rubber material forming the rubber elastic layer is not particularly limited. 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 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, a polyol, and diamine as a hardening | curing agent further to a prepolymer. Moreover, in order to prolong pot life, you may use the block type thing which 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 (prepolymer for block type polyurethane) and the like. The type A hardness (JIS K6253) of the rubber material used for the rubber elastic layer is preferably 80 ° or less, and more preferably 30 to 60 °. 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 stress concentrates in the place where the toner is densely laid during the primary transfer. The phenomenon is likely to occur. On the other hand, when 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.

  A particulate or spherical filler having an average particle size of 0.4 to 8 μm is added to the rubber elastic layer of the intermediate transfer belt of the present invention, and the filler is unevenly distributed on the surface layer side in the rubber elastic layer. It is characterized by being. Here, the surface layer side in the rubber elastic layer refers to a portion within about 20 μm from the surface layer side of the rubber elastic layer.

  The shape of the filler is amorphous or regular particles or spheres, and the sphere shape is particularly preferable because the friction coefficient of the belt surface can be reduced.

  The average aspect ratio (major axis / minor axis) of the filler used in the present invention is preferably 5 or less, and more preferably 3 or less. In the case of a needle-like or plate-like filler having a large average aspect ratio, a fine hardness distribution is generated on the belt surface, and taking a halftone image having a low image density is not preferable because noise appears. In the present invention, “particulate” refers to those having an average aspect ratio of greater than 1.2 to 3.0 or less, and “spherical” refers to those having an average aspect ratio of 1 to 1.2. .

  Here, in the present invention, the “average aspect ratio” can be measured as follows.

  Using an electron microscope (manufactured by Hitachi, Ltd., SEM, S-4800), the filler was photographed at a magnification of 1,000 to 10,000 times, and one random sample was obtained from the particles in the obtained micrograph. Select a particle and measure the long and short diameters of the particle using a ruler. The measured ratio of the major axis to the minor axis (major axis / minor axis) is calculated as the aspect ratio. The same operation is performed for other 19 randomly selected particles, and the average value of the total 20 aspect ratios is defined as the average aspect ratio.

  Here, the minor axis is a combination of two parallel lines in contact with the outer side of the filler particles in the micrograph, so that the filler particles are sandwiched, and two of these combinations that are the shortest intervals. This is the distance between parallel lines (dotted lines in FIG. 3). On the other hand, the major axis is two parallel lines that are perpendicular to the parallel line that determines the minor axis, and two parallel lines that are the longest interval among the combinations of two parallel lines that contact the outside of the filler particles ( This is the distance of the broken line in FIG. The rectangle formed by these four lines is sized to fit the filler particles just within it.

  The volume average particle diameter (median diameter D50) of the filler powder is 0.4 to 8 μm, preferably 0.5 to 5 μm, and particularly preferably 0.6 to 4 μm. When the particle diameter is larger than 8 μm, a fine hardness distribution is generated on the belt surface like the filler having a large aspect ratio, and noise appears in the image, which is not preferable. On the other hand, when the thickness is less than 0.4 μm, since the filler is less likely to be unevenly distributed on the surface layer side, stress concentration on the surface layer cannot be prevented, and cracking of the surface layer tends to occur.

  The average particle diameter of the filler in the rubber elastic layer in the intermediate transfer belt of the present invention can also be determined by SEM cross section observation or the like. Since the rubber elastic layer is formed by dispersing the filler in the resin solution, a part of the agglomeration proceeds during the solvent removal and the like. In the rubber elastic layer, the average particle diameter of the filler powder itself is slightly (about 1-2 μm). Degree) The average particle size tends to increase. Therefore, when the filler powder having the average particle size of 0.4 to 8 μm is used, the average particle size of the filler in the rubber elastic layer is about 1.4 to 10 μm.

  The amount of filler added is preferably 0.4 or more in terms of volume fraction relative to the rubber elastic layer, more preferably 0.4 to 4.0%, and still more preferably 0.4 to 3.5%. If the amount of the filler is too large, the hardness of the entire rubber elastic layer tends to be high and a good image tends not to be maintained. If the amount is too small, the portion in contact with the surface layer is soft, preventing stress concentration on the surface layer. There is a tendency not to.

  The intermediate transfer belt of the present invention is characterized in that the filler is unevenly distributed on the surface layer side in the rubber elastic layer. The uneven distribution of the filler is on the surface layer side in the rubber elastic layer. This can be expressed by the ratio of the filler mass concentration to the filler mass concentration at other locations. Specifically, it is as follows.

Mass concentration M _{1 of} filler contained in a region (A in FIG. 4) from the interface between the surface layer and the rubber elastic layer to a depth of 20 μm toward the substrate layer side, and the substrate from the interface between the surface layer and the rubber elastic layer Mass concentration M _{2 of} filler contained in a region having a depth of 60 to 80 μm toward the layer side (B in FIG. 4), a depth of 120 to 140 μm from the interface between the surface layer and the rubber elastic layer toward the base material layer side The mass concentration M _{3 of the} filler contained in the region (C in FIG. 4).

A mass concentration M ₁ of filler contained in the region from the interface of the surface layer and the rubber elastic layer to a depth 20μm towards the base layer side, the depth direction from the interface between the surface layer and the rubber elastic layer on the substrate layer side The ratio (M ₁ / M ₃ ) of the mass concentration M ₃ of the filler contained in the region of 120 to 140 μm is preferably 1.3 or more, and more preferably 1.5 or more.

A mass concentration M ₁ of filler contained in the region from the interface of the surface layer and the rubber elastic layer to a depth 20μm towards the base layer side, the depth direction from the interface between the surface layer and the rubber elastic layer on the substrate layer side The ratio (M ₁ / M ₂ ) of the mass concentration M ₂ of the filler included in the region of 60 to 80 μm is preferably 1.2 or more, and more preferably 1.4 or more.

A larger mass concentration ratio (M ₁ / M ₃ , M ₁ / M ₂ ) indicates that the filler is unevenly distributed on the surface layer side in the rubber elastic layer. When M ₁ / M ₃ is 1.3 or more and M ₁ / M ₂ is 1.2 or more, the rubber hardness is high only in the region in contact with the surface layer of the rubber elastic layer, so stress concentration on the surface layer is avoided. In addition, it is preferable because an intermediate transfer belt having excellent durability can be obtained while maintaining a high-quality image.

  The filler concentration ratio within the above range indicates that the filler is unevenly distributed on the surface layer side in the rubber elastic layer. By unevenly distributing the filler in this manner, the hardness of the entire rubber layer is not increased, and only the contact portion with the surface layer is increased in hardness so that stress concentration on the surface layer can be prevented.

  Here, the mass concentration of the filler is measured by measuring the mass concentration of main elements constituting the filler with an energy dispersive X-ray analyzer (EDX) (acceleration voltage: 20 kV, irradiation time: 5 minutes). It is. For example, when the filler is aluminum borate, the aluminum concentration is measured, and when the filler is zirconium oxide, the zirconium concentration is measured.

  In addition, since the measurement by EDX is performed for a 20 μm × 20 μm region, an arbitrary 20 μm × 20 μm region is measured three times for each region (for example, a portion surrounded by a thick line in FIG. 4 is measured). The average value was taken as the filler concentration in that region.

  The method of unevenly distributing the filler is not particularly limited, and examples thereof include a method of forming a film by forcibly uneven distribution on the surface layer side by centrifugal molding described later.

  As fillers to be blended, zirconium oxide, magnesium sulfate, barium sulfate, aluminum borate, calcium silicate, boron nitride, aluminum nitride, alumina, titanium oxide, talc, (true) spherical silica, calcium carbonate, zinc oxide, carbon black , PTFE, glass beads and the like. Among these, particulate zirconium oxide, magnesium sulfate, barium sulfate, aluminum borate, spherical silica, alumina, and glass beads are preferable. Further, the filler may be appropriately treated with a coupling agent or the like according to the combination of the filler and the rubber elastic layer.

  Moreover, a hardening | curing agent can be added to the said composition for elastic layer formation as needed. For example, in the case of silicone rubber, hydrogen organopolysiloxane can be used as the curing agent, and in the case of urethane rubber, diisocyanate, polyol, or diamine can be used as the curing agent. These curing agents may be used by blending in the rubber elastic layer material.

  When adding a curing agent, the addition amount is set to 1: 1 the number of reactive functional groups of the rubber main agent and the curing agent, so the same equivalent may be mixed, but in the case of highly reactive substances such as diisocyanate, Taking into account that it becomes inactive by reacting with water, etc., it is preferably 1 to 1.2 times equivalent.

  Although the solid content concentration of the elastic layer forming composition can be appropriately set depending on the production method, it is usually preferably about 20 to 70% by weight including the filler.

  The method for preparing the elastic layer forming composition is not particularly limited, but it is preferable to mix using a ball mill after blending the materials. The rubber elastic layer has a thickness of 200 to 400 μm, preferably 200 to 350 μm, and more preferably 200 to 300 μm. When the thickness of the rubber elastic layer is within the above range, the contact pressure between the photoconductor and the transfer belt can be kept low, the toner on the photoconductor aggregates, and the center of the line image does not transfer. The phenomenon can be prevented, and at the same time, color misregistration that is likely to occur when the transfer belt is too thick can be prevented.

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. The surface layer is formed of a surface layer material in which a resin is dissolved or dispersed in an organic solvent or water.

  As the resin used for the surface layer, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (PFA), tetra Examples thereof include a copolymer of fluoroethylene and hexafluoropropylene (FEP), a copolymer of tetrafluoroethylene and ethylene (ETFE), polyimide, and polyamideimide. Among these, a fluorine-based resin is particularly preferable from the viewpoints of friction coefficient and wear resistance, and polyvinylidene fluoride and a copolymer of vinylidene fluoride and hexafluoropropylene are particularly preferable from the viewpoint of electrical characteristics.

  Further, a layered clay mineral may be added to the surface layer, and examples of the layered clay mineral include smectite and hydrotalcite.

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

  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 still more preferably 1 to 5% by weight with respect to the total weight of the surface layer. By blending the layered clay mineral at such a ratio, even if the surface layer of the transfer belt is made thin, excellent rough paper transfer performance and durability can be realized with little generation of pinholes.

  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.

  The surface layer can be formed by applying and drying a surface layer material obtained by dissolving or swelling the resin and the optionally added layered clay mineral in an organic solvent on the inner surface of a cylindrical mold or the like. .

  The organic solvent in which the resin is dissolved or swollen is not particularly limited. For example, 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.

  In the present invention, a solution obtained by dissolving and swelling a resin and a layered clay mineral in an organic solvent is allowed to stand for about 48 to 72 hours, and then a surface layer material that is not visually observed is used as a surface layer material. It is desirable to use it.

  The surface roughness (Rz) of the surface layer is preferably 0.25 to 1.5 μm, more preferably 0.4 to 1.3 μm, and even more preferably 0.5 to 1.2 μm. When the surface roughness is less than 0.25 μm, it tends to stick to a sliding member such as a roll, which causes torque over during driving, and when it exceeds 1.5 μm, the toner sticks. This is not preferable because it causes image defects such as (filming) and voids. In the present invention, the surface roughness of the surface layer indicates the surface roughness measured in the surface layer of the intermediate transfer belt of the present invention comprising a base material layer, an elastic layer, and a surface layer.

  In the present invention, the thickness of the surface layer is 0.5 to 6 μm, preferably 1 to 4 μm, and more preferably 2 to 4 μm. If the thickness of the surface layer exceeds the above range, the rubber elasticity of the elastic layer is impaired. In addition, when the thickness of the surface layer is less than the above range, there is a problem in durability such as easy perforation.

  The Young's modulus of the surface layer is preferably 300 to 2,000 MPa, more preferably 500 to 1,200 MPa. When the Young's modulus is 2,000 MPa or less, it is possible to prevent line break-out due to stress concentration on the toner, and when the Young's modulus is 300 MPa or more, the friction coefficient of the surface layer is prevented from increasing, and secondary transfer is performed. This is preferable because deterioration of efficiency can be prevented.

The volume resistivity of the surface layer is usually preferably 1 × 10 ¹² Ω · cm or more, more preferably 1 × 10 ¹² to 1 × 10 ¹⁵ Ω · cm, and further preferably 1 × 10 ¹² to 1 × 10 ¹⁴ Ω · cm. preferable. In the present invention, the volume resistivity and Young's modulus of the surface layer are determined by preparing a surface layer single film having a thickness of 10 μm using the composition for forming the surface layer, and measuring the volume resistivity and Young's modulus of the film. Is shown.

1.4 Properties of Intermediate Transfer Belt The intermediate transfer belt of the present invention has the following properties.

(IRHD hardness of intermediate transfer belt)
The IRHD hardness of the intermediate transfer belt is preferably 82 IRHD or less, and more preferably 70 to 82 IRHD. By being within the above range, an intermediate transfer belt excellent in “rough paper transferability” can be obtained. The IRHD hardness can be measured according to JIS K6253.

(Intermediate transfer belt surface roughness)
The intermediate transfer belt of the present invention has high surface accuracy, and the surface roughness of the surface layer is preferably about 0.25 to 1.5 μm in terms of 10-point average roughness (Rz: JIS B0601-1994), and 0.4 to 1 About 3 μm is more preferable, and about 0.5 to 1.2 μm is more preferable.

(Static friction coefficient and volume resistivity of the surface of the intermediate transfer belt)
The static friction coefficient of the surface of the intermediate transfer belt of the present invention is preferably 0.1 to 0.8, more preferably about 0.1 to 0.6, and further preferably 0.1 to 0.4. 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 preferably about 1 × 10 ⁸ to 1 × 10 ¹⁴ Ω · cm. This range is variable depending on the amount of conductive agent added to the elastic layer and / or the base material layer.

  The average total thickness of the intermediate transfer belt of the present invention is usually about 100 to 400 μm, preferably about 150 to 350 μm. The thickness of each layer can be appropriately set in consideration of the stress and flexibility applied to the belt during driving, but the ratio of the thickness of each layer is usually 1.5 to 5 when the base material layer is 1. About 0.0, preferably about 2 to 4; the surface layer is about 0.005 to 0.05. By adopting a three-layer process as described later, variations in the thickness of the belt are reduced, and a homogeneous belt can be manufactured.

2. Manufacturing method of intermediate transfer belt for image forming apparatus The manufacturing method of the intermediate transfer belt for image forming apparatus having the above-described configuration is not particularly limited, and examples thereof include the following methods.

The intermediate transfer belt for an image forming apparatus of the present invention can be obtained by a manufacturing method including the following steps.
(1) A step of forming a base material layer by centrifugal molding or melt extrusion molding of a resin,
(2) A solution obtained by dissolving or swelling a resin in an organic solvent is subjected to centrifugal molding using a cylindrical mold having a surface roughness (Rz) of 0.25 to 1.5 μm, and the thickness is 0.00. A step of forming a surface layer of 5 to 6 μm,
(3) A step of forming a rubber elastic layer having a thickness of 200 to 400 μm by centrifugal molding on the inner surface of the surface layer obtained in (2) above to form a two-layer film, and (4 ) A step of superposing the outer surface of the base material layer obtained in the above (1) and the inner surface of the rubber elastic layer of the two-layer film obtained in the above (3), and performing a heat treatment.

Or after forming a surface layer and a base material layer by said (1) and (2), respectively, the outer surface of a base material layer is piled up on the inner surface of (3 ') surface layer, and an elastic layer is formed between both layers It can also be manufactured by injecting a material and heat-treating it.

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.

2.1 Step (1) (Formation of substrate 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 ).

  Centrifugal acceleration (G) is derived from the following formula (I).

G (m / s ² ) = r · ω ² = r · (2 · π · n) ² (I)
Here, 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.

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

  The composition for forming a surface layer is subjected to centrifugal molding using a cylindrical mold having a surface roughness (Rz) of 0.25 to 1.5 μm. In this case, it prepares so that the thickness of the surface layer obtained may be set to about 0.5-6 micrometers.

  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 rotational speed is gradually increased, the rotation is increased to a centrifugal acceleration 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 0.25 to 1.5 μm, a surface layer having a surface roughness (Rz) of 0.25 to 1.5 μm corresponding to it 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.

2.3 Step (3) (2 layers)
On the inner surface of the surface layer obtained in the step (2), an elastic layer obtained by centrifugal molding of the elastic layer material is formed into 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 and subjected to centrifugal molding. Heat treatment is performed while rotating at a centrifugal acceleration of twice or more (preferably 2 to 20 times). By setting the rotational speed of the rotating drum to a centrifugal acceleration that is at least twice the gravitational acceleration, a centrifugal force that is always greater than the gravitational acceleration is always applied to the raw material solution, so that the filler having a higher specific gravity than the resin tends to segregate on the surface layer side. Therefore, it is preferable.

  In the heating, the inner surface of the drum is gradually heated to reach about 90 to 180 ° C, preferably about 90 to 150 ° 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.

  When the rubber elastic layer is made into two layers, the elastic layer material is further centrifugally molded on the inner surface of the rubber elastic layer formed in advance, and similarly heated and cured.

2.4 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 having a dry lamination adhesive or the like applied to the outer surface is inserted 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, 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, and it heat-processes. Thus, the elastic layer can also be manufactured by simultaneously forming the film and forming the three layers (step (3 ′)).

2.5 Step (3 ′) (elastic layer formation and three-layer formation)
The surface layer and the base material layer separately formed according to the above steps (1) and (2) 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.

  The intermediate transfer belt of the present invention obtained by the method as described above is excellent in durability while maintaining a high-quality image. Therefore, electrophotography such as copying machines (including color copying machines), printers, facsimiles, etc. It can be suitably used as an intermediate transfer belt of an image forming apparatus adopting this method. The intermediate transfer belt of the present invention can form a good halftone image.

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

  Measurement methods for the following various physical property values are shown.

<Surface roughness>
The surface roughness (μm) was measured according to JIS B0601-1994. The measuring machine used was a Keyence laser microscope VK-9700, and the observation conditions were 1000 times the objective lens 20 times x eyepiece 50 times. Using the image of the belt surface obtained by observation, the line roughness was measured under the following measurement conditions.

Tilt correction: Surface tilt correction (automatic)
Cut-off: None Measurement length: 0.25 mm.

  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.

<Young's modulus>
The Young's modulus was measured using Autograph AG-X manufactured by Shimadzu Corporation in accordance with JIS K7127.

Sample piece 25 × 250 mm strip shape Tensile speed 20 mm / min <Confirmation of uneven distribution of filler>
The belt cross section was sliced with a microtome, and gold vapor deposition was performed so that the vapor deposition thickness was 5 nm to prepare an observation sample. About the sample for observation, cross-sectional observation with the electron microscope (SEM: S-4800 by Hitachi, Ltd.) was performed.

Further, the mass concentration M _{1 of the} filler contained in the region up to a depth of 20 μm from the interface between the surface layer and the rubber elastic layer toward the substrate layer side, and from the interface between the surface layer and the rubber elastic layer toward the substrate layer side. Mass concentration M _{2 of} filler contained in a region having a depth of 60 to 80 μm, and mass concentration M _{3 of} filler contained in a region having a depth of 120 to 140 μm from the interface between the surface layer and the rubber elastic layer toward the base material layer. , EDX (HORIBA, Ltd., energy dispersive X-ray analyzer EMAX model 7593H, acceleration voltage: 20 kV, irradiation time: 5 minutes), and the respective concentration ratios (M ₁ / M ₂ , M ₁ / M ₃ ) Asked.

  The mass concentration of the filler by EDX was measured by measuring the mass concentration of the main element constituting the filler (the aluminum concentration when the filler is aluminum borate, and the zirconium concentration when the filler is zirconium oxide). At this time, the mass concentration of gold deposited for observation was deleted from the total mass concentration so that the total mass concentration other than gold was 100%. Moreover, the measurement by EDX measured the arbitrary area | region of 20 micrometers x 20 micrometers 3 times in each each area | region, and made the average value the filler density | concentration of the area | region.

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. The number average molecular weight of this polyamic acid solution was 19,000, the viscosity was 40 poise, and the solid content concentration was 18.1% by weight.

  Next, 21 g of acidic carbon black (pH 3.0) and 80 g of N-methyl-2-pyrrolidone were added to 450 g of this polyamic acid solution, and carbon black (CB) was uniformly dispersed by a ball mill. This master batch solution had a solid concentration of 18.6% by weight and a CB concentration in the solid content of 20.5% by weight.

  And 273g was extract | collected from this solution, and it inject | poured in the rotating drum, and shape | molded on 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 solution was uniformly applied to the drum inner surface while rotating the rotating drum, 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 79 μm, an outer peripheral length of 944.3 mm, a surface resistivity of 2 × 10 ¹¹ to 4 × 10 ¹¹ Ω / □, and a volume resistivity of 1 × 10 ^{9 to} 3 × 10 ⁹ Ω · cm.
(2) Film formation of surface layer 100 g of VdF-HFP copolymer resin (Kyner # 2821, Arkema: HFP 11 mol%), which is a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), It was dissolved in 900 g of N-dimethylacetamide (DMAc) to prepare a solution A having a solid content concentration of 10% by weight.

  100 g of organically modified montmorillonite (Lucentite STN, manufactured by Coop Chemical Co., Ltd.) was added to 900 g of dimethylacetamide and uniformly dispersed by a ball mill to prepare a solution B having a solid content concentration of 10% by weight.

  Solution A and solution B were mixed at A: B = 99: 1 and mixed with a paint shaker to obtain a solution having a solid content of 10% by weight and an organically modified montmorillonite concentration of 1% by weight in the solid. This was diluted with a mixed solvent of DMAc: butyl acetate = 1: 2, solid content concentration 1.6% by weight, organic modified montmorillonite concentration in the solid content 1% by weight (corresponding to the blending ratio of montmorillonite with respect to the total weight of the surface layer) Solution) (hereinafter also referred to as surface layer material). A film of 112 g of this solution was formed 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) = 0.5 μm was placed on two rotating rollers and arranged to rotate with the rotation of the rollers. (See, for example, FIG. 2).

  While rotating the rotating drum, the coating was uniformly applied to the inner surface of the drum 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. It was 2 micrometers when the thickness of the surface layer formed in the drum inner surface was measured with the eddy current type thickness meter (made by Kett Chemical Laboratory).

In addition, using the above-mentioned surface layer material, a surface layer of 10 μm was separately produced under the same film forming conditions. The volume resistance value of the 10 μm surface layer was 4 × 10 ¹² Ω · cm, the Young's modulus was 610 MPa, and the surface roughness (Rz) of the surface layer was 0.6 μm.
(3) Film formation of elastic layer An average aspect ratio of 2.3, amorphous as a filler in a solution obtained by dissolving 141.3 g of a block-type urethane prepolymer (Urehyper RUP1627, manufactured by Dainippon Ink, Inc.) in 188 g of toluene 7.93 g of particulate barium sulfate (BALIACE B-54, average particle diameter D50 = 1.2 μm, manufactured by Sakai Chemical Industry Co., Ltd.) was added, and uniform dispersion was performed with a ball mill. Furthermore, 11.07 g (manufactured by Dainippon Ink Co., Ltd.) of an aliphatic diamine-based curing agent CLH-5 was added to the dispersion and stirred.

  The solution thus obtained had a solid content of 46% by weight, barium sulfate in the solid content of 5.0% by weight, and a volume fraction of 1.31%. This dispersion was uniformly applied to the inner surface of the surface layer previously formed in a rotating state, and heating was started. The heating was performed at 1 ° C./min up to 150 ° C., and the heating was continued for 30 minutes while maintaining the rotation to form a rubber elastic layer on the inner surface of the drum.

  The rotational speed of the rotating drum in this heating stage was 7.4 times the centrifugal acceleration of the gravitational acceleration.

In general, the gravitational acceleration (g) is 9.8 (m / s ² ).

  Centrifugal acceleration (G) is derived from the following formula (I).

G (m / s ² ) = r · ω ² = r · (2 · π · n) ² (I)
Here, 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.

  The resulting rubber elastic layer had a thickness of 258 μm.

The rubber elastic layer single films formed in the same manner except that no filler was added to the elastic layer urethane raw material solution were laminated so as to have a thickness of 10 mm, and the type A hardness was measured to be 40 °.
(4) Lamination of rubber elastic layer inner surface and polyimide outer surface Apply primer DY39-067 (manufactured by Toray Dow Corning) to the rubber elastic layer inner surface formed in (3) above, air-dry, then apply dry lami adhesive thinly on the outer surface The polyimide belt (1) 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 333 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.39, a surface resistivity of 1 × 10 ^{11 to} 3 × 10 ¹¹ Ω / □, and a volume resistivity of 4 × 10 ^{10 to} 6 × 10 ¹⁰ Ω. cm, and the surface roughness (Rz) was 0.5 μm.

Further, cross-sectional observation with an electron microscope (SEM) and barium mass concentration ratio (M ₁ / M ₂ , M ₁ / M ₃ ) by EDX were measured, and M ₁ / M ₂ = 1.8, M ₁ / M ₃ = 2.1. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Example 2
The filler compounded in the rubber layer is an amorphous particulate zirconium oxide having an average aspect ratio of 2.1 (UEP zirconium oxide, average particle diameter D50 = 0.6 μm, manufactured by Daiichi Rare Element Chemical Co., Ltd.), and A multilayer belt was produced in the same manner as in Example 1 except that the amount was 8% by weight and the volume fraction was 1.63%.

The obtained multilayer belt has a thickness of 340 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.36, a surface resistivity of 3 × 10 ^{11 to} 5 × 10 ¹¹ Ω / □, and a volume resistivity of 8 × 10 ¹⁰ to 1 × 10 ^11. The Ω · cm and the surface roughness (Rz) were 0.8 μm.

Moreover, when cross-sectional observation with an electron microscope (SEM) and zirconium mass concentration ratios (M ₁ / M ₂ , M ₁ / M ₃ ) by EDX were measured, M ₁ / M ₂ = 2.5, M ₁ / M ₃ = It was 2.8. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Example 3
Zirconium oxide blended in the rubber layer is an amorphous particulate zirconium oxide having an average aspect ratio of 1.9 (EP zirconium oxide, average particle diameter D50 = 1.1 μm, manufactured by Daiichi Rare Elemental Chemical Co., Ltd.) A multilayer belt was produced in the same manner as in Example 2 except that the amount was 5% by weight and the volume fraction was 1.02%.

The obtained multilayer belt has a thickness of 339 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.38, a surface resistivity of 1 × 10 ¹¹ to 4 × 10 ¹¹ Ω / □, and a volume resistivity of 5 × 10 ¹⁰ to 8 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

Moreover, when cross-sectional observation with an electron microscope (SEM) and zirconium mass concentration ratios (M ₁ / M ₂ , M ₁ / M ₃ ) by EDX were measured, M ₁ / M ₂ = 2.8, M ₁ / M ₃ = It was 3.1. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Example 4
A multilayer belt was produced in the same manner as in Example 3 except that the amount of zirconium oxide blended in the rubber layer was 3% by weight and the volume fraction was 0.62%.

The obtained multilayer belt has a thickness of 337 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.40, a surface resistivity of 1 × 10 ¹¹ to 2 × 10 ¹¹ Ω / □, and a volume resistivity of 4 × 10 ^{10 to} 6 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

The Measurement of the zirconium mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 3.4, M 1 / M 3 = It was 3.9. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Example 5
The filler to be blended in the rubber layer was amorphous particulate aluminum borate having an average aspect ratio of 1.7 (Arbolite PF-03, average particle diameter D50 = 2.6 μm, manufactured by Shikoku Kasei Kogyo Co., Ltd.). A multilayer belt was produced in the same manner as in Example 1 except that the amount was 3% by weight and the volume fraction was 1.17%.

The obtained multilayer belt has a thickness of 338 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.33, a surface resistivity of 3 × 10 ^{11 to} 6 × 10 ¹¹ Ω / □, and a volume resistivity of 5 × 10 ^{10 to} 9 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

The Measurement of the aluminum mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 1.4, M 1 / M 3 = It was 1.5. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Example 6
The filler compounded in the rubber layer is spherical silica having an average aspect ratio of 1.1 (SP30, average particle diameter D50 = 2.6 μm, manufactured by Micron Co., Ltd.), and its amount is 5% by weight, and the volume fraction is 2. A multilayer belt was produced in the same manner as in Example 1 except that the content was 77%.

The obtained multilayer belt has a thickness of 342 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.25, a surface resistivity of 1 × 10 ^{11 to} 3 × 10 ¹¹ Ω / □, and a volume resistivity of 2 × 10 ^{10 to} 5 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

The Measurement of the silicon mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 4, M 1 / M 3 = 4. It was 5. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Example 7
The filler compounded in the rubber layer is spherical silica having an average aspect ratio of 1.1 (S-0, average particle diameter D50 = 3.7 μm, manufactured by Micron Corporation), and its amount is 5% by weight, volume fraction. A multilayer belt was produced in the same manner as in Example 1 except that the content was 2.77%.

The obtained multilayer belt has a thickness of 342 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.27, a surface resistivity of 1 × 10 ^{11 to} 3 × 10 ¹¹ Ω / □, and a volume resistivity of 2 × 10 ^{10 to} 5 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.9 μm.

The Measurement of the silicon mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 2.9, M 1 / M 3 = It was 4.7. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Comparative Example 1
A multilayer belt was produced in the same manner as in Example 1 except that no filler was added to the rubber layer.

The obtained multilayer belt has a thickness of 328 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.48, a surface resistivity of 2 × 10 ^{11 to} 5 × 10 ¹¹ Ω / □, and a volume resistivity of 4 × 10 ^{10 to} 7 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.6 μm.

Comparative Example 2
Except for using 5.53 g of CLH-5 (Dainippon Ink Co., Ltd.) and 4.09 g of 4,4-methylenebis (2-methylcyclohexaneamine) (Dainippon Ink Co., Ltd.) as the curing agent. A multilayer belt was produced in the same manner as in Comparative Example 1.

  The rubber elastic layer single films formed by forming the elastic layer urethane raw material solution in the same manner were laminated so as to have a thickness of 10 mm, and the type A hardness was measured to be 55 °.

The obtained multilayer belt has a thickness of 330 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.43, a surface resistivity of 3 × 10 ^{11 to} 6 × 10 ¹¹ Ω / □, and a volume resistivity of 4 × 10 ¹⁰ to 8 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.6 μm.

Comparative Example 3
Except for using 2.21 g of CLH-5 (Dainippon Ink Co., Ltd.) and 6.55 g of 4,4-methylenebis (2-methylcyclohexaneamine) (Dainippon Ink Co., Ltd.) as the curing agent. A multilayer belt was produced in the same manner as in Comparative Example 1.

  The rubber elastic layer single films formed by forming the elastic layer urethane raw material solution in the same manner were stacked so as to have a thickness of 10 mm, and the type A hardness was measured to be 71 °.

The obtained multilayer belt has a thickness of 328 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.37, a surface resistivity of 4 × 10 ^{11 to} 7 × 10 ¹¹ Ω / □, and a volume resistivity of 6 × 10 ^{10 to} 9 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.5 μm.

Comparative Example 4
The filler to be blended was made into acicular aluminum borate having an average aspect ratio of 21.6 (Arborex, average particle diameter D50 = 20 μm, manufactured by Shikoku Kasei Kogyo Co., Ltd.) 3% by weight, volume fraction 1.17%. A multilayer belt was produced in the same manner as in Example 1 except for the above.

The obtained multilayer belt has a thickness of 331 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.31, a surface resistivity of 1 × 10 ^{11 to} 3 × 10 ¹¹ Ω / □, and a volume resistivity of 5 × 10 ¹⁰ to 8 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

The Measurement of the aluminum mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 39.7, M 1 / M 3 = It was 54.6. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Comparative Example 5
The filler to be blended is 2% by weight of acicular potassium titanate having an average aspect ratio of 23.5 (Tismo D, average particle diameter D50 = 15 μm, manufactured by Otsuka Chemical Co., Ltd.) and a volume fraction of 0.71%. Produced a multilayer belt in the same manner as in Example 1.

The obtained multilayer belt has a thickness of 331 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.37, a surface resistivity of 1 × 10 ¹¹ to 2 × 10 ¹¹ Ω / □, and a volume resistivity of 7 × 10 ¹⁰ to 1 × 10 ^11. The Ω · cm and the surface roughness (Rz) were 0.8 μm.

The was then measured for Ti mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 1.1, M 1 / M 3 = 1.1. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm from the interface layer side to the base material layer side and the filler concentration in the central portion of the rubber layer were almost the same. .

Comparative Example 6
Except that the filler to be blended was a plate-like mica having an average aspect ratio of 8.0 (Somasif MTE, average particle diameter D50 = 6.0 μm, manufactured by Coop Chemical Co., Ltd.) 5% by weight, and volume fraction 2.17%. Produced a multilayer belt in the same manner as in Example 1.

The obtained multilayer belt has a thickness of 341 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.31, a surface resistivity of 5 × 10 ^{10 to} 7 × 10 ¹⁰ Ω / □, and a volume resistivity of 3 × 10 ^{10 to} 5 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

Moreover, when cross-sectional observation with an electron microscope (SEM) and silicon mass concentration ratios (M ₁ / M ₂ , M ₁ / M ₃ ) by EDX were measured, M ₁ / M ₂ = 4.1, M ₁ / M ₃ = It was 6.0. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Comparative Example 7
The filler compounded in the rubber layer is spherical silica (S-COX88) having an average aspect ratio of 1.1, average particle diameter D50 = 8.5 μm, manufactured by Micron Co., Ltd., and its amount is 5% by weight, volume fraction A multilayer belt was produced in the same manner as in Example 1 except that the rate was 2.77%.

The obtained multilayer belt has a thickness of 344 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.31, a surface resistivity of 2 × 10 ^{11 to} 3 × 10 ¹¹ Ω / □, and a volume resistivity of 3 × 10 ¹⁰ to 8 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 1.6 μm.

Moreover, when cross-sectional observation with an electron microscope (SEM) and silicon mass concentration ratios (M ₁ / M ₂ , M ₁ / M ₃ ) by EDX were measured, M ₁ / M ₂ = 5.9, M ₁ / M ₃ = It was 6.0. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm toward the base material layer is higher than the central portion of the rubber layer. .

Comparative Example 8
The filler compounded in the rubber layer is an amorphous particulate zirconium oxide having an average aspect ratio of 1.9 (UEP zirconium oxide, average particle diameter D50 = 0.25 μm, manufactured by Daiichi Rare Element Chemical Industries, Ltd.) A multilayer belt was produced in the same manner as in Example 1 except that the amount was 5% by weight and the volume fraction was 1.02%.

The obtained multilayer belt has a thickness of 339 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.37, a surface resistivity of 1 × 10 ¹¹ to 2 × 10 ¹¹ Ω / □, and a volume resistivity of 6 × 10 ¹⁰ to 8 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

The Measurement of the zirconium mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 1.1, M 1 / M 3 = 1.1. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm from the interface layer side to the base material layer side and the filler concentration in the central portion of the rubber layer were almost the same. .

Comparative Example 9
The filler compounded in the rubber layer is an amorphous particulate barium sulfate (BALIACE B-30, average particle diameter D50 = 0.3 μm, manufactured by Sakai Chemical Industry Co., Ltd.) having an average aspect ratio of 2.1, and the amount thereof is A multilayer belt was produced in the same manner as in Example 1 except that the content was 5% by weight and the volume fraction was 1.02%.

The obtained multilayer belt has a thickness of 343 μm, an outer peripheral length of 945.0 mm, a static friction coefficient of 0.40, a surface resistivity of 1 × 10 ^{11 to} 3 × 10 ¹¹ Ω / □, and a volume resistivity of 4 × 10 ^{10 to} 7 × 10 ^10. The Ω · cm and the surface roughness (Rz) were 0.7 μm.

The Measurement of the barium mass concentration ratio by section observation and EDX with an electron microscope _{(SEM) (M 1 / M} 2, M 1 / M 3), M 1 / M 2 = 1.1, M 1 / M 3 = It was 1.2. From this, it was confirmed that the concentration of the filler contained in the region from the interface between the surface layer and the rubber elastic layer to the depth of 20 μm from the interface layer side to the base material layer side and the filler concentration in the central portion of the rubber layer were almost the same. .

<Halftone image evaluation>
A full-tone halftone (image density: 30% magenta) image was printed, and the obtained image was magnified 50 times to confirm the presence or absence of noise generated over the entire image.

○: No noise at all △: Slight noise is observed ×: Clear noise is recognized <Secondary transfer efficiency (rough paper transferability)>
Using a Strathmore Lighting Raid manufactured by Strathmore with an unevenness of about 50 μm, the entire solid image (image density: 100% magenta) and the toner on the deepest portion (concave portion) were visually judged. The evaluation criteria are as follows.

◎: Completely uniform transfer is possible ○: Slightly light color △: Slightly white is missing ×: There is no toner applied and white is missing <Durability test for passing paper>
Under the following conditions, paper feeding, energization, and driving tests were performed simultaneously. After driving tests equivalent to 100,000 sheets, the surface layer was observed for cracks and peeling with a microscope, and the belt surface roughness and image quality were confirmed. Cracking and peeling were evaluated according to the following evaluation criteria.

Driving speed: Belt outer peripheral speed 300 mm / sec. Energization: Power supply (Trek 610C) supplies a constant current of 50 .mu.A in the belt thickness direction. Paper feed: A state in which copy paper is wrapped around the outer surface of the secondary transfer roll and pseudo continuous paper is passed. Cleaning mechanism: Urethane rubber cleaning blade (rubber hardness type A 80 °)
(Surface layer crack)
Evaluation of cracks was performed using a Keyence laser microscope VK-9700.

  Belt endurance before and after endurance is measured at 1,000 times the objective lens 20 times x eyepiece 50 times, and the image of the belt surface obtained by observation is used to measure the line roughness as follows. (Measured in accordance with JIS B0601-2001).

Tilt correction: Surface tilt correction (automatic),
Cut-off: None,
Measurement length: 0.25 mm.

  Measure five different surface parts in the same belt, calculate the average value of the maximum valley depth Rv, and subtract Rv before paper passing durability from the Rv value after paper passing durability [Rv (paper passing durability After) -Rv (before paper passing durability)].

○: Less than 0.3 μm △: 0.3-0.6 μm
×: Over 0.6 μm <IRHD rubber hardness>
According to JIS K6253, rubber hardness was measured from the surface layer side of the belt using an IRHD micro hardness tester (model number: H12 type, manufactured by Wallace).

Claims (5)

(A) a resin base layer;
(B) a rubber or elastomer rubber elastic layer having a thickness of 200 to 400 μm;
(C) a resin surface layer having a thickness of 0.5 to 6 μm;
An intermediate transfer belt for an image forming apparatus including at least the three layers,
A particulate or spherical filler having an average particle diameter of 0.4 to 8 μm is added to the rubber elastic layer,
A mass concentration M ₁ of filler contained in the region from the interface of the surface layer and the rubber elastic layer to a depth 20μm towards the base layer side, toward the interface between the surface layer and the rubber elastic layer on the substrate layer side An intermediate transfer belt for image formation, wherein a ratio (M ₁ / M ₃ ) of mass concentration M ₃ of fillers contained in a region having a depth of 120 to 140 μm is 1.3 or more. The intermediate transfer belt for image formation according to claim 1, wherein the filler has an average particle diameter of 0.4 to 5 μm. The amount of filler added to the rubber elastic layer is 0.4% or more in volume fraction, and the IRHD hardness (JIS K6253) measured from the surface layer side is 82 IRHD or less. An intermediate transfer belt for image formation as described in 1. The intermediate transfer belt for image formation according to any one of claims 1 to 3, wherein the rubber elastic layer is formed by a centrifugal molding method. The intermediate transfer belt for image formation according to claim 4, wherein the rotational speed in the centrifugal molding method is a centrifugal acceleration that is twice or more the gravitational acceleration (9.8 m / s ² ).

Images