JP2007131790A - Semi-conductive belt and image-forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semi-conductive belt which can increase a stress on the low extension of an elastic belt, can decrease a permanent elongation, can reduce the occurrence of micro slips, and can stably give good uniform transferability and good uniform image qualities over long periods, and to provide an image-forming device equipped with the semi-conductive belt. <P>SOLUTION: This semi-conductive belt having a substrate and a surface layer is characterized in that the substrate comprises a rubber, a non-fibrous resin and a fibrous resin, and has a durometer hardness of A50/S to A85/S, and the semi-conductive belt has a tensile stress of 4 to 25 MPa in an elongation of 3% and a permanent elongation of ≤2% in an elongation of 3%. The image-forming device equipped with the semi-conductive belt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductive belt used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to a semiconductive belt made of an elastic material and an image forming apparatus using the same.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, an image is formed on an image carrier such as a photosensitive drum, and this image is indirectly applied to a recording material via a semiconductive belt (intermediate transfer belt). There are already provided ones that transfer and those that directly transfer to a recording material on a semiconductive belt (paper conveying belt). In particular, in recent years, there is a tendency to use a small-diameter spherical toner as a toner in order to obtain a high quality transfer image quality. Since the toner having such a small diameter and spheroid is easily moved, a problem of scattering due to a transfer electric field is likely to occur.

From the viewpoint of maintaining good transfer performance of the image from the image carrier in the intermediate transfer belt (or paper transport belt), the first problem is that the intermediate transfer belt (or paper transport belt) and the image carrier are It is necessary to apply sufficient pressure to the nip area of the intermediate transfer belt or the intermediate transfer belt (or the sheet conveying belt) and the transfer member and to improve the adhesion. Further, as a second problem, the volume resistivity of the intermediate transfer belt (or the paper conveying belt) is controlled to a semiconductive region in the range of 1 × 10 ⁸ Ωcm to 1 × 10 ¹² Ωcm, and the variation is suppressed. It is necessary.

  In order to solve the first problem, there has already been provided a belt substrate itself of a semiconductive belt formed of an elastic material such as a flexible rubber. However, when using a flexible rubber, the stress at low elongation is small and the permanent elongation rate (creep) is large, so the rubber stretches (deforms) due to belt tension, and color misregistration over time. Problems arise and the belt life is shortened. In addition, when a belt using a flexible rubber comes into contact with an opposing member (such as an image carrier), the belt deforms in a direction along the surface due to friction with the member or adhesiveness of the belt surface, and tries to return to the original state. Since the stress is generated, there is a problem that a slight slip occurs between the surface of the semiconductive belt and the facing member (hereinafter referred to as “micro slip”), and color registration shift occurs.

  As an example of suppressing the elongation of a belt using rubber, a method is known in which a yarn is used as a belt elongation stopper, and the yarn is wound and molded (see, for example, Patent Document 1). This belt has a configuration in which an intermediate transfer body is formed by embedding a core made of a woven fiber in a spiral shape or the like in a base layer made of an elastomer or a resin. However, a belt using yarn is not suitable for mass production because it takes a very long time to wind the yarn around a drum and the cost is high.

  Furthermore, a method is known in which a woven fabric is used as a belt stretcher and rubber is applied to the woven fabric to form an endless belt. Specifically, one or more fiber layers and one or both surfaces of the fiber layers are known. An intermediate transfer member having an elastic layer laminated thereon is proposed (see, for example, Patent Document 2). In addition, an intermediate transfer belt has been proposed which has a core structure inside and has a layer configuration of two or more layers including an elastic layer and a coating layer whose distance between fibers is 50 μm or more and 3000 μm or less (for example, Patent Document 3). reference). However, in any case, in order to make the woven fabric endless, it is necessary to use a bag weave. At that time, it is very difficult to make the woven density constant. As a result, there is a defect that image unevenness occurs due to non-uniformity of the weave density when used as an intermediate transfer belt.

  As a method for eliminating the drawbacks of these molding methods, a method has been proposed in which carbon black or a fiber-shaped filler is mixed into rubber paste obtained by making acrylic rubber into a paste with a solvent such as toluene, and then the solvent is blown off after molding. (For example, refer to Patent Document 4). However, this method has a drawback that when the rubber is formed into a paste, the fiber-shaped filler is non-uniformly dispersed, and image unevenness occurs when used as an intermediate transfer belt. Moreover, since it takes time to remove a solvent such as toluene, the cost is high and it is not suitable for mass production. Furthermore, it is necessary to take measures such as fire prevention by making the rubber into a paste with a solvent such as toluene, and there is a problem that additional equipment costs are required.

Next, as a method for solving the second problem, a method of adding a conductive agent such as carbon black or a conductive metal oxide such as tin oxide to rubber is known, but the volume resistivity is 1 × 10. ^The semiconductive region in the range of ⁸ Ωcm or more and 1 × 10 ¹² Ωcm or less is a region where resistance control is difficult, and a desired resistance value may not be obtained stably. This is because it is difficult to uniformly disperse a conductive agent such as carbon black in the rubber, resulting in poor dispersion.

  For example, a transfer conveyance belt using an elastic body such as chloroprene rubber in which carbon black or the like is dispersed is already known, but even if normal conductive carbon black is added to normal rubber, the desired resistance value is stabilized. Can hardly get. That is, it is difficult to manufacture the elastic belt with variations in resistance within one digit (log Ωcm), and when the in-plane variation in resistance is larger by one digit or more, the transfer voltage cannot be applied uniformly, so that the transfer image quality can be reduced. There is a problem that is not stable. Furthermore, in order to transfer the toner image to the transfer material, a transfer voltage of 1 kV to 5 kV must be applied. This applied voltage changes the resistance value of the belt, and the portion of the transfer material and the transfer material There arises a problem in that the resistance value varies between different parts.

  In addition, if a mixed base material of chloroprene rubber and ethylene propylene diene rubber is used as the belt base material of the semiconductive belt, excellent ozone resistance and flame retardancy can be exhibited, and the bleed phenomenon can be effectively utilized. A technique that can be avoided has already been provided (see, for example, Patent Document 5). Further, this Patent Document 5 discloses that dispersion of acetylene black, furnace black and acetylene black, or acetylene black and ketjen black in a belt base material can suppress fluctuations in electrical resistance over time. Is also disclosed.

  However, when fillers such as carbon black and metal compounds are dispersed in the belt in this way, the resistance variation in the belt due to the dispersed state of the filler is as large as about one digit or more, and between the filler and filler. There are problems similar to those of the conventional semiconductive belt, such as a decrease in resistance of the belt over time due to minute dielectric breakdown and rearrangement of filler due to energization. As described above, when the printout is performed, the volume resistivity of the belt over time is partially or entirely deviated from the range of good volume resistivity, and there is a problem that the image quality is deteriorated.

  On the other hand, as a method for controlling the resistance value in the semiconductive region, a method of using a rubber having ion conductivity, for example, acrylonitrile butadiene rubber (NBR), epichlorohydrin rubber (ECO), etc., and adding a conductive agent. It has been known.

As for acrylonitrile butadiene rubber (NBR), it is common to use acrylonitrile content in the range of 15 mass% or more and 50 mass% or less. When the acrylonitrile content is the above ratio, the volume resistivity is stable in a high resistance region (a range of about 10 ⁹ Ωcm to about 10 ¹² Ωcm), and when used alone, There are problems such as a narrow adjustment range and large environmental dependency of electrical resistance (a large difference between a resistance value in a high temperature and high humidity environment and a resistance value in a low temperature and low humidity environment).

In view of this, a technique has been proposed in which carbon black and an ionic conductive agent (a quaternary ammonium salt or the like) are added to NBR (see, for example, Patent Document 6). In this method, it is possible to control the resistance value to a predetermined medium resistance region (a range of about 10 ⁷ Ωcm or more and about 10 ¹² Ωcm or less) by electron conduction using carbon black and ion conduction using an ionic conductive agent. . However, in this case, the NBR used as the matrix is stable in volume resistance in the high resistance region as described above, so a large amount of carbon black and an ionic conductive agent must be blended. The addition amount of the ionic conductive agent becomes excessive, and problems such as blooming (exudation) occur. Further, if the conductive mode depends on the electron conduction by carbon black, there arises a problem that variation in electric resistance becomes large due to the influence of the amount of carbon black added and the dispersion state. Furthermore, the conductive mode depending on the electron conduction by carbon black also has a large voltage dependency of the electric resistance, so that there is a problem that the resistance value is likely to fluctuate due to a change in voltage.

In addition, epichlorohydrin rubber (ECO) includes epichlorohydrin homopolymer or a copolymer of epichlorohydrin and ethylene oxide. When ethylene oxide is copolymerized, the higher the ethylene oxide content in the composition, the more resistant it is. The value becomes lower. ECO is generally used in the range of ethylene oxide content of 20 mol% or more and 65 mol% or less. When the ethylene oxide content is the above ratio, the volume resistivity is stable in a low resistance region (a range of about 10 ⁵ Ωcm or more and about 10 ⁸ Ωcm or less), but in a high temperature and high humidity environment and a low temperature and low humidity environment. The difference in common logarithm of resistivity is 2 or more, and there is a problem that the environment dependency is large.

Then, the method of mix | blending an ionic conductive agent (quaternary ammonium salt etc.) with ECO is known (for example, refer patent documents 7-10). In this method, in addition to the property of ECO having high ion conductivity, the resistance value can be controlled to a predetermined resistance region by the effect of the ion conductive agent. In this case, since the ionic conductivity of the ECO itself is high, problems such as variations in electrical resistance and voltage dependency are unlikely to occur. However, since the electrical resistance is also highly dependent on the environment, there arises a problem that the electrical resistance tends to fluctuate due to changes in temperature and humidity.
Japanese Patent Laid-Open No. 9-251246 JP-A-10-232572 Japanese Patent Laid-Open No. 11-84901 JP 10-48963 A JP-A-9-179414 Japanese Patent Laid-Open No. 06-264918 Japanese Patent Laid-Open No. 06-264919 Japanese Patent Laid-Open No. 10-059453 Japanese Patent Laid-Open No. 10-221927 JP 2000-274427 A

The present invention has been made to solve the above technical problems, and it is an object of the present invention to achieve the following objects.
That is, the present invention increases the stress at the time of low elongation of the elastic belt, reduces the permanent elongation, further reduces the occurrence of micro slip, and obtains stable and good uniform transferability and image quality over a long period of time. An object of the present invention is to provide a semiconductive belt and an image forming apparatus including the same.

Means for solving the above-described problems can be achieved by the present invention described below.
That is, the present invention
<1> In the semiconductive belt having a base material and a surface layer, the base material contains rubber, a non-fiber-shaped resin, and a fiber-shaped resin, and the durometer hardness of the base material is A50. / S to A85 / S, and the semi-conductive belt has a tensile stress at 3% elongation of 4 Mpa to 25 MPa, and a permanent elongation at 3% of 2% or less. It is a semiconductive belt.

<2> The base material is contained in a range of 25 to 50 parts by mass of a non-fibrous resin and in a range of 20 to 30 parts by mass of a fibrous resin with respect to 100 parts by mass of rubber. The semiconductive belt according to <1>.

<3> The semiconductive belt according to <1> or <2>, wherein the rubber includes epichlorohydrin rubber and acrylonitrile-butadiene rubber.

<4> The semiconductive belt according to any one of <1> to <3>, wherein the base material has a volume resistivity of 1 × 10 ⁸ Ωcm or more and 1 × 10 ¹² Ωcm or less.

<5> The semiconductive belt according to any one of <1> to <4>, wherein a resin layer containing a fluororesin is provided as the surface layer.

<6> The semiconductive belt according to any one of <1> to <5>, wherein the volume resistivity is in the range of 1 × 10 ⁸ Ωcm to 1 × 10 ¹² Ωcm.

<7> An image forming apparatus including the semiconductive belt according to any one of <1> to <6>.

<8> The image forming apparatus according to <7>, wherein the semiconductive belt is stretched around a plurality of stretching rolls and is arranged in contact with the drum-shaped image carrier.

<9> The image forming apparatus according to <7> or <8>, wherein the semiconductive belt is provided as an intermediate transfer belt and / or a paper transport belt.

<10> The image forming apparatus according to any one of <7> to <9>, wherein a spherical toner having a shape factor SF defined by the following formula (1) in a range of 140 to 100 is used.
Formula (1)
SF = [(maximum length of toner particles) ² / (projected area of toner particles)] × π / 4 × 100

  According to the present invention, it is excellent in forming a nip shape in the transfer portion, and even when it is always in contact with the image carrier, there is extremely little transfer image quality defect due to elongation (deformation) of the semiconductive belt, and rubber is used. Since the occurrence of microslip generated when used is small, deterioration of color registration can be suppressed, and a semiconductive belt with little change in electrical resistance with time can be provided. Further, this semiconductive belt can be suitably used as an intermediate transfer belt and a paper transport belt in an image forming apparatus such as an electrophotographic apparatus, and a high-quality transfer image quality can be stably obtained.

<Semiconductive belt>
The semiconductive belt of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing an example of a semiconductive belt of the present invention. In this case, the semiconductive belt 1 is an endless belt having a two-layer structure including a surface layer 2 and a base material 3. The base material 3 contains rubber, a non-fiber-shaped resin, and a fiber-shaped resin, and the durometer hardness is in the range of A50 / S to A85 / S. The surface layer 2 is made of a material having a small surface energy such as a resin containing a fluororesin. Further, the semiconductive belt 1 of the present invention has a tensile stress at 3% elongation of 4 MPa or more and 25 MPa or less, and a permanent elongation at 3% elongation of 2% or less, compared with a conventional elastic belt. Elongation is small.
The “semiconductive belt” in the present invention means a belt having a volume resistivity in the range of 1 × 10 ⁸ Ωcm to 1 × 10 ¹² Ωcm.

By making the base material 3 contain rubber, a non-fibrous resin and a fibrous resin, the tensile stress at low elongation can be increased, and the permanent elongation can be decreased. it can. Further, the non-fibrous resin can improve the processability at the time of manufacture, and the semiconductive belt 1 can be manufactured with high productivity.
Further, it is preferable that the base material 3 does not contain solids such as carbon black and metal oxide for imparting conductivity, and has a certain degree of flexibility while having the above-described tensile stress and permanent elongation. A conductive belt is obtained. Therefore, it can be suitably used as an intermediate transfer belt or a paper transport belt in an image forming apparatus such as an electrophotographic apparatus.
In addition to the base material 3 and the surface layer 2, the semiconductive belt 1 of the present invention is provided with an elastic layer, a surface protective layer and other layers, and may be further multilayered within a range not impairing the effects of the present invention. it can. Hereafter, each structure of the semiconductive belt of this invention is demonstrated in detail.

(Base material)
The semiconductive belt base material of the present invention contains rubber, non-fibrous resin, and fibrous resin, and its durometer hardness is in the range of A50 / S to A85 / S. In general, in order to improve the tensile stress at the time of low elongation of rubber, it is known to fill a large amount of insulating inorganic filler such as calcium carbonate, silica, talc, clay, titanium oxide, In order to improve the tensile stress, it is known to add a fiber-shaped inorganic filler. However, the use of these inorganic fillers and fiber-shaped fillers significantly deteriorates belt properties, kneading processability and molding processability as the filling amount increases.

Therefore, in the present invention, instead of these inorganic fillers, a non-fiber-shaped resin and a fiber-shaped resin described later are included in the rubber. Non-fiber shaped resins are softened by heat during kneading to lower the viscosity, so that kneading processability can be improved, and after the rubber is cured, the tensile stress at low elongation is improved. As a result, even if rubber is used, it is possible to satisfy both the characteristics of high tensile stress at the time of low elongation and permanent elongation required as an intermediate transfer belt.
In addition, by aligning the fiber-shaped resin in the direction along the belt surface (direction perpendicular to the thickness direction), the deformation of the base material can be suppressed, and the base material is simply The problem of microslip that occurs when an elastic material is used does not occur.

-Rubber-
The rubber constituting the base material is preferably a single rubber having conductivity, for example, epichlorohydrin rubber (ECO), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), acrylic rubber (ACM), polysulfide rubber (T). , Urethane rubber (U) and the like are preferable from the viewpoints of resistance controllability and belt processability. By using these rubbers, the desired volume resistance of the semiconductive region can be obtained without blending a conductive agent such as carbon black. Therefore, the base material obtained by the present invention is a base material with less in-plane resistance unevenness without sacrificing the flexibility inherent to rubber.

  These rubbers can be used alone, but are preferably mixed and used. When mixed and used, it is preferable to mix so that the rubber having relatively high conductivity has a larger mass ratio than other rubbers. For example, when ECO and NBR are mixed and used, the mass ratio (ECO / NBR) is preferably in the range of 50/50 to 90/10, and more preferably in the range of 60/40 to 80/20. When the mass ratio is less than 50/50, a desired volume resistance value may not be obtained, and when it exceeds 90/10, a problem may occur in workability.

-Non-fibrous resin-
The non-fibrous resin acts as a softening agent during belt molding and can improve kneading processability. Furthermore, after the belt molding process, it becomes indeterminate and can be cross-linked with rubber to improve hardness and wear resistance, and improve tensile stress and permanent elongation. Since the non-fibrous resin is not compatible with rubber, a sea-island structure is formed on the molded base material, and the resin exists as an amorphous island in the sea of rubber.
The term “indefinite shape” as used herein means that the shape of any non-fibrous resin contained in the semiconductive belt is not constant and has various shapes. The formation of the sea-island structure can be confirmed by cutting out a thin piece from the surface of the molded substrate and observing it with a microscope.

  Examples of non-fiber shaped resins include phenolic resins, thermosetting urethane resins, epoxy resins, reactive monomers, and other thermosetting resins, or polyvinyl chloride (PVC), polyvinyl acetate (PVA), thermoplastic urethane, and the like. A thermoplastic resin having a low viscosity in a temperature range of 100 ° C. or more and 160 ° C. or less, which is a heating temperature at the time of belt molding, can be preferably used. Specifically, PR-12686, PR-13349, PR-13355 manufactured by Sumitomo Bakelite Co., Ltd., which is a phenol resin surface-treated with hexamine, is preferably used. These can be used individually by 1 type or in mixture of 2 or more types.

  The volume average particle size of the non-fibrous resin used for producing the semiconductive belt is preferably in the range of 1 μm to 2000 μm, and more preferably in the range of 5 μm to 1000 μm. When the volume average particle size is less than 1 μm, the workability may deteriorate, and when it exceeds 2000 μm, poor dispersion may occur.

  The amount of the non-fibrous resin added to the rubber is preferably in the range of 20 parts by weight to 60 parts by weight and more preferably in the range of 25 parts by weight to 50 parts by weight with respect to 100 parts by weight of the rubber. preferable. When the addition amount is less than 20 parts by mass, the workability is improved, but the tensile stress and permanent elongation of the obtained semiconductive belt may be deteriorated. On the other hand, when the addition amount exceeds 60 parts by mass, the characteristics of the non-fibrous resin are dominant, and the characteristics of the rubber are not utilized, and the surface of the semiconductive belt may be cracked.

-Fiber-shaped resin-
The fiber-shaped resin preferably has a length in the range of 0.1 mm to 20 mm, and more preferably in the range of 0.5 mm to 10 mm. If the length is less than 0.1 mm, it becomes difficult to orient the major axis in the direction along the belt surface (perpendicular to the thickness direction), and if it exceeds 20 mm, the major axis moves in the belt thickness direction. This is not preferable because it may cause bending.

The fiber-shaped resin preferably has a fineness in the range of 10 tex to 60 tex (1 tex = 1 × 10 ⁻⁶ kg / m), and more preferably in the range of 20 tex to 50 tex. If the fineness is less than 10 tex, in order to prevent micro-slip, a large amount must be blended in the base material. As a result, the molding solution becomes highly viscous, and the workability at the time of molding may be reduced. In addition, if the fineness is 60 tex or more, the smoothness of the belt surface may be impaired, and the processability of the base material may be deteriorated and molding may not be possible.

  Examples of the fiber-shaped resin include resin fibers such as cotton, hemp, silk, rayon, acetate, nylon, acrylic, vinylon, vinylidene, polyester, polystyrene, polypropylene, and aramid. Among them, an aramid fiber is preferably used because the fiber shape can be maintained in a temperature range of 100 ° C. or more and 160 ° C. or less, which is a heating temperature at the time of belt molding. For example, a chopped fiber having a fiber length in the range of 1 mm to 6 mm, such as Technora manufactured by Teijin Techno Product Co., Ltd., is preferably used.

  The addition amount of the fiber-shaped resin is preferably in the range of 10 to 40 parts by mass, more preferably in the range of 20 to 30 parts by mass with respect to 100 parts by mass of the rubber. When the addition amount is less than 10 parts by mass, sufficient strength cannot be obtained even when combined with other reinforcing agents, and when it exceeds 40 parts by mass, the workability deteriorates and molding is impossible.

As described above, to align the fiber-shaped resin in the direction along the belt surface (direction perpendicular to the thickness direction), the fiber-shaped resin is aligned in the molding direction. do it. For example, a method of applying a liquid containing the fiber-shaped resin on a layer formed on the outside or inside of a cylindrical mold while rotating (centrifugal molding method), a cylindrical mold having a layer formed on the outside By immersing the mold in a liquid containing the above fiber-shaped resin and drawing it out, using a method of applying the outermost surface of the cylindrical mold (dip molding method) or the like, the long axis is applied to the surface of the substrate. It can be oriented in the direction along (the direction perpendicular to the thickness direction).
Thus, by orienting the fiber-shaped resin in the direction along the belt surface (direction perpendicular to the thickness direction), the deformation of the substrate can be suppressed, The problem of microslip that occurs when only rubber is used is eliminated.

The volume resistivity of the substrate is preferably a semiconductive region having a volume resistivity in the range of 1 × 10 ⁸ Ωcm to 1 × 10 ¹² Ωcm, more preferably 1 × 10 ⁹ Ωcm to 1 × 10 ^11. It is the range below Ωcm. If the volume resistivity is in the range of 1 × 10 ⁸ Ωcm or more and 1 × 10 ¹² Ωcm or less, the toner is scattered around the image by the electrostatic repulsion between the toners or the fringe electric field near the image edge. The problem (blurring) that occurs is reduced. In addition, within the above range, the volume resistivity of the semiconductive belt (especially when applied to an intermediate transfer member) is in a range where the charged charge is appropriately attenuated. Image formation can be performed continuously.

  In the present invention, acrylonitrile butadiene rubber (NBR) and epichlorohydrin rubber having the above-mentioned ion conductivity are used from the viewpoint of controlling the volume resistance value in the semiconductive region and reducing variations in electrical resistance and voltage dependence due to environmental changes. It is preferable to use a combination of (ECO). Accordingly, the volume resistivity can be controlled in a predetermined semiconductive region by controlling the mass ratio within the above-described range without blending a conductive agent such as carbon black.

  In addition to the above non-fibrous resin, fibrous resin, conventional additives such as vulcanizing agents, vulcanization accelerators, vulcanization aids, co-crosslinking agents, anti-aging agents, softening materials Agents, plasticizers, etc. may be included in the rubber. These additives may be used alone or in combination of two or more.

  As the vulcanizing agent, for example, sulfur, organic sulfur-containing compounds, and organic peroxides can be used. The amount of vulcanizing agent added to the rubber is usually preferably in the range of 0.1 to 30 parts by mass, more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber. is there.

  Examples of the vulcanization accelerator include thiurams such as magnesia (MgO), tetramethylthiuram disulfide and tetraethylenethiuram disulfide, dithiocarbamates such as zinc dibutyldithiocarbamate and zinc diethyldithiocarbamate, and 2-methylcaptobenzothiazole. , Thiazoles such as N-cyclohexyl-2-benzothiazole sulfinamide, and other thioureas. The amount of the vulcanization accelerator added to the rubber is usually preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.5 to 3 parts by weight with respect to 100 parts by weight of the rubber. It is.

Examples of the vulcanization aid include fatty acids such as zinc white, zinc oxide, metal oxide stearic acid, and oleic acid. The amount of vulcanization aid added to the rubber is usually preferably in the range of 0.5 to 10 parts by weight, more preferably in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the rubber. .

  As the co-crosslinking agent, ethylene glycol / dimethacrylate, trimethylolpropane / trimethacrylate, polyfunctional methacrylate monomer, triallyl isocyanurate, metal-containing monomer, etc. are conventionally used as co-crosslinking agents by organic peroxides. Are listed. The amount of the co-crosslinking agent added to the rubber is usually preferably 5 parts by mass or less, more preferably 3 parts by mass or less, relative to 100 parts by mass of the rubber.

  Examples of the antioxidant include imidazoles such as 2-mercaptobenzimidazole, amines such as phenyl-α-naphthylamine, N, N-di-β-naphthyl-P-phenylenediamine, and phenols such as styrenated phenol. And quinolines such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer. The amount of the anti-aging agent added to the rubber is usually preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.5 to 3 parts by weight with respect to 100 parts by weight of the rubber. is there.

  Examples of the softening agent include fatty acids such as stearic acid and paraffin wax. The amount of the softening agent added to the rubber is usually preferably in the range of 5 parts by mass or less, more preferably in the range of 3 parts by mass or less with respect to 100 parts by mass of the rubber.

  Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, and process oil. The amount of the plasticizer added to the rubber is usually preferably 5 parts by mass or less, more preferably 3 parts by mass or less, relative to 100 parts by mass of the rubber.

  The base material of the present invention can be produced by mixing the components described above with a mixer such as a tumbler, V-type blender, Nauter mixer, Banbury mixer, kneading roller, or extruder. In the production of the substrate in the present invention, the mixing method of each component and the order of mixing are not particularly limited. As a general method, there is a method in which all components are mixed in advance with a tumbler, V blender, etc., and uniformly melt-mixed by an extruder, but depending on the shape of the components, two or more types of molten mixtures in these components Alternatively, a method of melt-mixing the remaining components can be used.

The durometer hardness of the base material is in accordance with JIS K6253, and it is an essential requirement that it is in the range of A50 / S to A85 / S, and more preferably in the range of A60 / S to A80 / S. It is. When the durometer hardness of the elastic layer is less than A50 / S, there is a problem that the surface elongation due to the nip pressure becomes too large and the transfer image quality deteriorates. On the other hand, when A85 / S is exceeded, since the flexibility is poor and the nip shape cannot be secured, problems such as poor transfer image quality occur. In order to adjust the durometer hardness of the base material to the above range, the type of rubber may be appropriately selected, and the addition amount of the non-fibrous resin and the fibrous resin to be added to the rubber may be appropriately adjusted within the above range. The durometer hardness of the substrate can be increased as the addition amount of the non-fibrous resin and the fibrous resin is increased, and as the fineness of the fibrous resin is increased.
The durometer hardness of the base material is based on JIS K6253 (1997), and the standard hardness is measured using a type A durometer by stacking sheet-shaped base materials to a thickness of 6 mm.

(Surface layer)
In the present invention, a surface layer having toner releasability is provided on the surface of the substrate. As a material used for the surface layer, a material having a small surface energy such as a resin containing a fluororesin is preferably used. By reducing the surface energy of the surface of the semiconductive belt, it becomes difficult for dirt to adhere to the surface of the semiconductive belt, and contamination of the surface of the semiconductive belt can be effectively prevented. The surface layer may contain other components other than the fluororesin such as carbon black for developing conductivity.

-Resin-
The resin is not particularly limited as long as it is a material excellent in adhesion to the substrate, followability to deformation of the substrate, and toner releasability. For example, acetal resin such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide Resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, Examples thereof include phenol-formaldehyde resin and melamine resin. These resins are formed by dispersing a material having a small surface energy such as a fluororesin or a resistance control agent (particles). Among these resins, it is preferable to use a polyurethane resin from the viewpoint of adhesion to the base material and followability to deformation of the base material. Since the polyurethane resin is composed of a soft segment containing a long-chain polyol as a main component and a hard segment containing an isocyanate compound, it can easily follow the deformation of the substrate. Furthermore, by using a blocked isocyanate compound as a curing agent, bleeding (bleeding) of the low molecular component contained in the base material to the surface layer can be suppressed. When forming the surface layer, the use of a material that uses water as the solvent does not require the solvent material and other characteristics of the base material compared to ordinary solvent-based materials, and the solvent evaporates into the air. This is preferable because it has superiority such as excellent environmental performance.

-Fluororesin-
Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyvinylidene fluoride (PVDF), Tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinyl fluoride (PVF), fluoroolefin-vinyl ether copolymer, fluorine And resins such as vinylidene fluoride-tetrafluoroethylene copolymer and vinylidene fluoride-hexafluoropropylene copolymer. These may be used alone or in combination of two or more.

  Although content of the fluororesin contained in a surface layer is not specifically limited, It is preferable that it is the range of 30 to 70 mass parts with respect to 100 mass parts of resin, and is 40 to 60 mass parts. A range is more preferable. When the content of the fluororesin contained in the surface layer is less than 30 parts by mass, the surface energy of the surface of the semiconductive belt member is increased, so that dirt such as toner adhesion may be easily attached. is there. On the other hand, when the amount is more than 70 parts by mass, a component other than the fluororesin may not be contained in a necessary amount in the surface layer.

The thickness of the surface layer is preferably in the range of 5 μm to 100 μm, and more preferably in the range of 15 μm to 50 μm. When the thickness of the surface layer is less than 5 μm, the effect of preventing the contamination of the surface of the semiconductive belt member may not be obtained. On the other hand, when the thickness is larger than 100 μm, the surface hardness of the semiconductive belt member becomes unnecessarily large, so that sufficient adhesion to the surface of the image carrier may not be obtained.
In addition, when the thickness of the surface layer is 1/10 or less of the thickness of the base material, the influence of the surface layer on the properties of the semiconductive belt can be ignored, and the tensile stress and permanent elongation of the base material are determined. It can be regarded as the tensile stress and permanent elongation of the entire semiconductive belt.

The ten-point average surface roughness Rz of the surface layer in the semiconductive belt of the present invention is preferably in the range of 1.5 μm to 9.0 μm, and preferably in the range of 3.0 μm to 6.0 μm. More preferred. If the ten-point average surface roughness Rz is less than 1.5 μm, there is a concern that the ten-point average surface roughness Rz is in close contact with the contact member. And the like, and uneven discharge may occur due to the unevenness, so that the uniform transferability and image quality may deteriorate with time. The surface roughness Rz can be controlled by the type of resin and the addition amount of the fluororesin, and the ten-point average surface roughness Rz of the surface layer increases by increasing the addition amount of the fluororesin.
The ten-point average surface roughness Rz is the surface roughness specified in JIS B0601 (2001).

From the viewpoint of effectively preventing the surface of the semiconductive belt from being contaminated, the contact angle of the surface layer with respect to water (hereinafter abbreviated as “contact angle”) is in the range of 90 degrees to 130 degrees. Preferably, it is in the range of 95 degrees to 125 degrees, and more preferably in the range of 110 degrees to 120 degrees. When the contact angle of the surface layer with respect to water is less than 90 degrees, dirt such as toner sticking gradually accumulates and accumulates on the surface of the semiconductive belt member, so that uniform transferability and image quality over time. May decrease. If it exceeds 130 degrees, the toner transferred to the surface of the semiconductive belt is difficult to be held, and the uniform transferability may be reduced. The contact angle can be controlled by the type of resin and the addition amount of the fluororesin, and the contact angle to water can be increased by increasing the addition amount of the fluororesin.
The contact angle of the surface layer can be measured using a goniometer or the like.

The semiconductive belt of the present invention having the configuration described above has an essential requirement that the tensile stress at 3% elongation is in the range of 4 MPa to 25 MPa, and more preferably in the range of 5 MPa to 20 MPa. .
If the tensile stress at the time of 3% elongation is less than 4 MPa, there will be a problem of the belt stretching due to the tension applied to the belt itself when the belt is running, and if it exceeds 25 MPa, the load for obtaining the belt tension will increase. If the device breaks without being able to withstand the load, and if it can withstand the load, a problem such as an increase in the size of the device occurs.

  In addition, the semiconductive belt of the present invention has a tensile stress at 1% elongation of 2 MPa or more in addition to the tensile stress at 3% elongation from the viewpoint of suppressing change in the belt circumference during storage. Preferably, it is 3 MPa or more. If the tensile stress at the time of 1% elongation is less than 2 MPa, there may occur a problem that the belt stretches when the belt is stored.

Furthermore, the semiconductive belt of the present invention has an essential requirement that the permanent elongation at the time of 3% elongation is 2% or less, and more preferably 1% or less. If the permanent elongation at the time of 3% elongation exceeds 2%, there will be a problem that the belt is stretched due to belt tension when the belt is running.
The tensile stress and permanent elongation at the time of 3% elongation of the semiconductive belt, the tensile stress at the time of 1% elongation, the type of rubber is appropriately selected, and the non-fibrous resin and the fibrous resin to be added to the rubber are described above. The amount of non-fibrous resin and fibrous resin added can be increased as the amount of the non-fibrous resin and the fibrous resin is increased. The tensile stress can be increased, and the permanent elongation at 3% elongation can be decreased.

  The shape of the semiconductive belt of the present invention may be endless, and it may be formed by a suitable connection method such as an adhesive method using an adhesive or the like at the film end to form a seamless endless belt. The seamless endless belt has an advantage that the control mechanism for the rotation start position can be omitted because there is no change in the thickness of the joint and any portion can be set as the rotation start position.

<Image forming apparatus>
The present invention is directed to an image forming apparatus using the above-described semiconductive belt (for example, a transfer conveyance belt and an intermediate transfer belt).
In this case, as shown in FIG. 2, for example, the present invention includes an image carrier 6a and a paper conveyance belt 5a facing the image carrier 6a. The toner image formed on the image carrier 6a is transferred onto the paper conveyance belt 5a. In the image forming apparatus for transferring to the recording material 7a, the above-described semiconductive belt is used as the paper conveying belt 5a. Further, as another aspect of the present invention, for example, as shown in FIG. 3, the image bearing member 6b and an intermediate transfer belt 5b opposed to the image bearing member 6b are provided, and a toner image formed on the image bearing member 6b is intermediate-transferred. In the image forming apparatus for transferring to the belt 5b, the above-described semiconductive belt is used as the intermediate transfer belt 5b.

Here, in a mode in which the semiconductive belt 5a is used as a paper transport belt (recording material holding belt), as shown in FIG. 2, the recording material 7a is placed on the paper transport belt (recording material holding belt) 5a. After the holding, the toner image on the image carrier 6a is transferred to the recording material 7a on the paper conveying belt (recording material holding belt) 5a by the transfer device 8a.
On the other hand, in the embodiment in which the semiconductive belt 5b is used as an intermediate transfer belt, as shown in FIG. 3, the toner image on the image carrier 6b is transferred to the semiconductive belt (intermediate transfer belt) by the primary transfer device 8b. ) After primary transfer to 5b, the toner image on the semiconductive belt (intermediate transfer belt) 5b is secondarily transferred to the recording material 7b by the secondary transfer device 4b.

  In the image forming apparatus shown in FIG. 2 (or FIG. 3), the semiconductive belt 5a (or 5b) is stretched around a plurality of stretching rolls 9a (or 9b), and the drum-shaped image carrier 6a (or The aspect arrange | positioned in contact along the shape of 6b) is preferable. According to this aspect, by causing the semiconductive belt 5a (or 5b) to follow the shape of the image carrier 6a (or 6b) as much as possible, discharge due to useless gaps before and after the nip region during transfer is eliminated. Further, scattering of the toner image can be prevented.

  Further, in the image forming apparatus shown in FIG. 2 (or FIG. 3), one of the image carrier 6a (or 6b) and the semiconductive belt 5a (or 5b) is used as a drive source, and the other is driven to rotate. This embodiment is preferable. According to this aspect, by adopting such a drive configuration, one drive mechanism can be omitted, the drive cost can be reduced correspondingly, and the semiconductive belt 5a (or 5b) and the image carrier can be reduced. Variation factors such as thickness variation of the semiconductive belt 5a (or 5b) resulting from drive interference with 6a (or 6b) and feed variation in the process direction can be excluded.

FIG. 4 shows another embodiment of an image forming apparatus to which the present invention is applied. In FIG. 1, an image forming apparatus follows a shape of a photosensitive drum 10 in a predetermined area to the photosensitive drum 10 and a photosensitive drum 10 for transferring a toner image from the photosensitive drum (image carrier) 10. The intermediate transfer belt 20 in contact therewith.
In the present embodiment, the photosensitive drum 10 includes a photosensitive layer whose resistance value is reduced by light irradiation. Around the photosensitive drum 10, a charging device 11 for charging the photosensitive drum 10 and , An exposure device 12 for writing an electrostatic latent image of each color component (yellow, magenta, cyan, black in this example) on the charged photosensitive drum 10, and each color component latent image formed on the photosensitive drum 10. Are provided with a rotary developing device 13 that visualizes each of the color component toners, an intermediate transfer belt 20, and a cleaning device 17 that cleans residual toner on the photosensitive drum 10.

  Here, as the charging device 11, for example, a charging roll is used, but a charging device such as a corotron may be used. The exposure device 12 may be any device that can write an image on the photosensitive drum 10 with light. In this example, for example, a print head using LEDs is used, but the present invention is not limited to this. The print head used may be selected as appropriate, such as a scanner that scans a laser beam with a polygon mirror. Further, the rotary type developing device 13 is rotatably mounted with developing units 13a to 13d containing respective color component toners. For example, the respective color component toners are attached to the portions of the photosensitive drum 10 where the potential is lowered by exposure. The toner to be used is not particularly limited in shape and particle size, and any toner may be used as long as it is accurately placed on the electrostatic latent image on the photosensitive drum 10. In this example, the rotary developing device 13 is used, but four developing devices may be used. Furthermore, the cleaning device 17 may be appropriately selected as long as it cleans the residual toner on the photosensitive drum 10 and employs a blade cleaning method. However, there may be a mode in which the cleaning device 17 is not used when toner having a high transfer rate is used.

  Further, as shown in FIG. 4, the intermediate transfer belt 20 is stretched between four stretching rolls 21 to 24, and is a photosensitive drum positioned between the rotary developing device 13 and the cleaning device 17. Only a predetermined contact area is disposed in close contact with the 10th surface. Here, the intermediate transfer belt 20 and the photosensitive drum 10 may be driven by separate drive systems, but in the present embodiment, the intermediate transfer belt 20 is a semiconductive belt having the above-described configuration. In addition, the intermediate transfer belt 20 is driven and rotated by using, for example, the photosensitive drum 10 as a driving source because it is disposed in contact with the circumferential surface of the photosensitive drum 10.

A primary transfer roll 25 as a primary transfer device is disposed in contact with a part of the contact area where the intermediate transfer belt 20 is in close contact with the photosensitive drum 10 from the back side of the intermediate transfer belt 20, and a predetermined primary transfer bias is applied. Applied. Furthermore, a secondary transfer roll 30 as a secondary transfer device is disposed opposite to the tension roll 22 of the intermediate transfer belt 20 with the tension roll 22 as a backup roll, for example, the secondary transfer roll 30. A predetermined secondary transfer bias is applied to the tension roller 22 and the tension roll 22 that also serves as a backup roll is grounded.
Furthermore, a cleaning member 26 as a belt cleaning device is disposed at a portion of the intermediate transfer belt 20 facing the stretching roll 23, and a predetermined cleaning bias is applied to the cleaning roll 26 so that the stretching roll 23 is stretched. The roll 23 is grounded. A recording material 40 such as paper is accommodated in a supply tray 41, supplied by a pickup roll 42, guided to a secondary transfer portion through a registration roll 43, and then to a fixing device 45 through a conveyance belt 44. It is conveyed and discharged to the outside of the machine such as a discharge tray through a transfer roll 46 and a discharge roll 47.

  Next, the operation of this image forming apparatus will be described. In FIG. 4, when the image forming apparatus starts an image forming operation, each color component toner image on the photosensitive drum 10 is sequentially formed and is primarily transferred onto the intermediate transfer belt 20 sequentially by the transfer electric field of the primary transfer roll 25. Thereafter, the toner image primarily transferred to the intermediate transfer belt 20 is secondarily transferred to the recording material 40 by the transfer electric field of the secondary transfer roll 30, and is carried to the fixing step.

  Even if the photosensitive drum 10 and the intermediate transfer belt 20 are always arranged in contact with each other, the bleed phenomenon can be prevented, so that a retract mechanism for separating the photosensitive drum 10 and the intermediate transfer belt 20 is not required. In accordance with the fact that an inexpensive elastic material can be used as the base material 3, it is possible to reduce the cost because it is not necessary to provide a retract mechanism.

  Further, in the present embodiment model, the intermediate transfer belt 20 is driven to rotate by driving the photosensitive drum 10, so that the drive control cost of the intermediate transfer belt 20 can be greatly reduced. Furthermore, since the contact width of the intermediate transfer belt 20 to the photosensitive drum 10 in the primary transfer is set to be very wide, for example, 50 mm or more, stable follow-up to the intermediate transfer belt 20 can be realized, and the transfer nip can be realized. Since there is no useless gap before and after the area, primary transfer is performed in a state where there is no scattering of toner due to discharge. In particular, in the present embodiment, since a wide transfer nip area between the photosensitive drum 10 and the intermediate transfer belt 20 is ensured, it is possible to reduce the pressure in the transfer nip area. The situation where the body drum 10 and the intermediate transfer belt 20 are completely in close contact with each other is more reliably avoided.

  In the present embodiment, the photosensitive drum 10 and the intermediate transfer belt 20 are placed in contact with each other in an overlapping state, and the intermediate transfer belt 20 is driven based on the driving force from the photosensitive drum 10. However, the present invention is not limited to this. The photosensitive drum 10 and the intermediate transfer belt 20 have separate drive systems, and the intermediate transfer belt 20 is linearly connected to the photosensitive drum 10. Of course, the present invention can also be applied to an embodiment in which contact is made.

  Furthermore, when the semiconductive belt of the present invention is incorporated and used as an intermediate transfer belt or transfer / conveying belt in an image forming apparatus, it is preferable to use a spherical toner as the toner. By using a spherical toner as the toner, the material constituting the transfer surface has a low surface hardness and a high volume resistance, thereby obtaining a high-quality transfer image quality free from image quality defects (holocharacter, blur, color registration). be able to.

However, the spherical toner means that the shape factor SF is 140 to 100. The shape factor is preferably from 130 to 100, and more preferably from 120 to 100. When the average shape factor SF is larger than 140, the transfer efficiency is lowered, and the deterioration of the image quality of the print sample can be visually confirmed.
Here, the shape factor SF is a factor defined by the following equation.
SF = [(maximum length of toner particles) ² / (projected area of toner particles)] × (π / 4) × 100

  In addition, the maximum length of toner particles and the measurement of the projected area of the toner particles were measured using an optical microscope image of 100 toners dispersed on a slide glass using a Luzex image analyzer (manufactured by Nireco Corporation, FT). It can be implemented by importing into a Luzex image analyzer through a video camera and processing the image.

  The spherical toner contains at least a binder resin and a colorant. In this spherical toner, particles having a volume average particle diameter of preferably 2 μm or more and 12 μm or less, and more preferably 3 μm or more and 9 μm or less can be used from the viewpoint of image quality.

  Binder resins include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate, and methyl acrylate. , Α-methylene aliphatic monocarboxylic esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl Homopolymers and copolymers of vinyl ethers such as methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone can be exemplified, Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. A polymer, polyethylene, polypropylene, etc. are mentioned. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax, and the like can also be mentioned.

  Colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 is a typical example.

  The spherical toner may be subjected to internal addition treatment or external addition treatment with a known additive such as a charge control agent, a release agent, or other inorganic fine particles. Typical examples of the releasing agent include low molecular polyethylene, low molecular polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Known charge control agents can be used, and azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination.

  As other inorganic fine particles, small-diameter inorganic fine particles having an average primary particle size of 40 nm or less are used for the purpose of powder flowability, charge control, etc., and if necessary, larger diameters are used to reduce adhesion. Inorganic or organic fine particles may be used in combination. As these other inorganic fine particles, known ones can be used. Examples thereof include silica, alumina, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate. In addition, the surface treatment of the small-diameter inorganic fine particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

  The spherical toner is not particularly limited by the production method, and can be obtained by a known method. Specifically, for example, the particles obtained by the kneading and pulverization method in which the binder resin and the colorant are mixed, pulverized, and classified, if necessary, the release agent and the charge control agent are mechanically impacted. Method of changing shape by force or heat energy, emulsion polymerization of binder resin polymerizable monomer, dispersion of formed dispersion, colorant, release agent and charge control agent as required Liquid emulsion, agglomeration, heat fusion to obtain spherical toner, emulsion polymerization aggregation method, polymerizable monomer to obtain binder resin, colorant, release agent, charge control agent as required A suspension polymerization method in which a solution such as a suspension is polymerized by suspending in an aqueous solvent, a binder resin and a colorant, and if necessary, a release agent and a charge control agent are suspended in an aqueous solvent and granulated. Examples thereof include a dissolution suspension method. In addition, a manufacturing method may be performed in which the spherical toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to give a core-shell structure. When the external additive is added, it can be produced by mixing the spherical toner and the external additive with a Henschel mixer or a V blender. In addition, when the spherical toner is manufactured by a wet method, it can be externally added by a wet method.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Example 1>
(Formation of substrate)
= Rubber compounding 1 =
Rubber: Epichlorohydrin rubber (Nippon ZEON Co., Ltd .: Gechron 3103): 70 parts by mass Rubber: Acrylonitrile butadiene rubber (Nippon Zeon Co., Ltd., Nipol DN-219): 30 parts by mass Vulcanizing agent: Sulfur (Tsurumi Chemical Industry Co., Ltd .: 200 mesh): 5 parts by mass, vulcanization accelerator: 2-mercaptobenzothiazole (Ouchi Shinsei Chemical Co., Ltd., Noxera-M): 1.5 parts by mass, vulcanization aid Agent: Zinc oxide (manufactured by Hakusuitec Co., Ltd .: R powder, volume average particle size 5 μm): 5 parts by mass Anti-aging agent: 2,2,4-trimethyl-1,2-dihydroquinoline polymer (Ouchi Emerging Chemical) Industrial Co., Ltd .: NOCRACK 224S): 1 part by mass, processing aid: stearic acid: 1 part by mass, plasticizer: bis (2-ethylhexyl) phthalate (Daihachi Chemical Co., Ltd .: DOP): 1 Part by mass / non-fiber shaped resin: phenol resin (manufactured by Sumitomo Bakelite Co., Ltd .: PR-13349, volume average particle size 200 μm): 20 parts by mass / fiber shaped resin: 1.0 mm in length (fineness: 39 tex) Aramid fiber chopped strand (manufactured by Teijin Techno Products Co., Ltd .: Technora): 20 parts by mass Here, the ethylene oxide content in the epichlorohydrin rubber is 35 mol%, and the acrylonitrile content in the acrylonitrile butadiene rubber is 33.5. % By mass.

The rubber composition 1 was put into a Banbury mixer and kneaded at an initial temperature of 50 ° C. for 2 minutes, and then the rubber composition was kneaded with two rolls. The obtained kneaded material was formed into a tube shape by a tube cross head extruder. Subsequently, the molded blend rubber was heated and vulcanized in a vulcanizing can with a pressurized steam at a temperature of 126 ° C. and a pressure of 1.5 kg / cm ² G to form a substrate. The obtained base material was placed on the outside of a metal tube, and the surface was polished to produce a base material. From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed at an enlargement magnification of 50, a non-fibrous resin island structure was formed in the rubber sea structure. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction). The obtained base material had a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 3 × 10 ⁹ Ωcm, and a durometer hardness of A65 / S.

-Volume resistivity-
The volume resistivity was measured according to JIS K6911 (1995) using a circular electrode (for example, Hiresta UPMCP-450 type UR probe manufactured by Dia Instruments Co., Ltd.). A method for measuring the volume resistivity will be described with reference to FIG. FIG. 5 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode. The circular electrode shown in FIG. 5 includes a first voltage application electrode A and a second voltage application electrode B. The first voltage application electrode A has a cylindrical electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the cylindrical electrode portion C and surrounding the cylindrical electrode portion C at a constant interval. Part D is provided. The base material T is sandwiched between the cylindrical electrode part C and the ring-shaped electrode part D and the second voltage application electrode B in the first voltage application electrode A, and the cylindrical electrode part C and the first electrode in the first voltage application electrode A The current I (A) flowing when the voltage V (V) is applied between the two voltage application electrodes B is measured, and the volume resistivity ρv (Ωcm) of the substrate T can be calculated by the following equation. . Here, in the following formula, t indicates the thickness of the substrate T.
Formula: ρv = 19.6 × (V / I) × t
In the measurement, under a 22 ° C./55% RH environment, a voltage of 100 (V) was applied between the cylindrical electrode portion C and the second voltage application electrode B in the first voltage application electrode A, and 10 seconds later. Obtained from the current value. The average value measured for a total of 24 points of 3 points in the length direction of the prepared substrate and 8 points in the circumferential direction was taken as the volume resistivity of the substrate.

−Durometer hardness−
The durometer hardness was measured according to JIS K6253 (1997), using durometer type A (manufactured by Kobunshi Keiki Co., Ltd .: ASKER A type). For the measurement, only the base material was stacked to a thickness of 6 mm.

(Formation of surface layer)
Following the formation of the substrate, a surface layer is formed. First, a two-component curable aqueous urethane-based resin mixed solution containing fluororesin particles and carbon black is prepared. A two-component curable water-based urethane resin coating (Emuralon 345: manufactured by Nippon Acheson Co., Ltd.) containing 10 parts by mass of carbon black (Ketjen Black EC: manufactured by Lion Aguzo Co., Ltd., volume average particle size 30 nm) and curing PTFE resin particles (30 parts by mass with respect to 100 parts by mass of the urethane resin component) in a solution obtained by mixing blocked isocyanate (WH-2: manufactured by Nippon Atison Co., Ltd.) as an agent at a mixing ratio of 100: 10 Teflon (registered trademark): manufactured by Mitsui DuPont Fluorochemical Co., Ltd., volume average particle size 0.3 μm) was mixed. The obtained mixed solution was spray-coated on the substrate surface, and then heated and dried at 120 ° C. for 15 minutes to form a surface layer having a thickness of 20 μm composed of fluororesin particles, carbon black, and urethane resin. The volume resistivity of the semiconductive belt manufactured as described above was 8 × 10 ⁹ Ωcm, the contact angle of water on the belt surface was 92 degrees, and the ten-point average surface roughness Rz was 3 μm. .

-Contact angle of water-
Water was dropped on the surface of the semiconductive belt in an environment of 23 ° C. and 55% RH, and the contact angle after standing for 10 seconds was measured using a contact angle measuring device (CA-X roll type: manufactured by Kyowa Interface Science Co., Ltd.). Measured. In addition, the average value measured repeatedly 3 times at different locations was defined as the contact angle of the belt.

-Ten-point average surface roughness Rz-
Ten-point average surface roughness Rz is measured in accordance with JIS B0601 (2001) using a contact-type surface roughness measuring device (Surfcom 570A: manufactured by Tokyo Seimitsu Co., Ltd.) in an environment of 23 ° C. and 55 RH%. did. When measuring the surface roughness of the semiconductive belt member, the reference length is 0.8 mm, the evaluation length is 4 mm, and the tip of the contact needle is diamond (5 μmR, 90 ° cone). The average value obtained by repeating the measurement three times was used as the ten-point average surface roughness Rz of the semiconductive belt surface.

<Example 2>
(Formation of substrate)
The thickness was 0.5 mm, the inner diameter was 140 mm, the width was 320 mm, and the volume resistivity was 5 × 10 ⁹ Ωcm, except that the amount of the non-fibrous resin added was changed to 30 parts by mass per 100 parts by mass of rubber. A substrate having a durometer hardness of A68 / S was produced.
From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed at an enlargement magnification of 50, a non-fibrous resin island structure was formed in the rubber sea structure. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction).

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 1 except that the carbon black content was changed to 15 parts by mass and the fluororesin particle content was changed to 40 parts by mass. The volume resistivity of the semiconductive belt manufactured as described above is 7 × 10 ⁹ Ωcm, the contact angle of water on the surface of the semiconductive belt is 105 degrees, and the ten-point average surface roughness Rz is 6 μm. there were.

<Example 3>
(Formation of substrate)
The same rubber composition was used in Example 1 except that the addition amount of the non-fibrous resin was changed to 30 parts by mass per 100 parts by mass of rubber, and the addition amount of the fibrous resin was changed to 30 parts by mass per 100 parts by mass of rubber. In the same manner as in Example 1, a base material having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 1 × 10 ¹⁰ Ωcm, and a durometer hardness of A72 / S was produced.
From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed at an enlargement magnification of 50, a non-fibrous resin island structure was formed in the rubber sea structure. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction).

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 1 except that the carbon black content was changed to 15 parts by mass and the fluororesin particle content was changed to 50 parts by mass. The volume resistivity of the semiconductive belt manufactured as described above is 2 × 10 ¹⁰ Ωcm, the contact angle of water on the surface of the semiconductive belt is 110 degrees, and the ten-point average surface roughness Rz is 8 μm. there were.

<Example 4>
(Formation of substrate)
The same rubber composition was used in Example 1, except that the addition amount of the non-fiber-shaped resin was changed to 40 parts by mass per 100 parts by mass of the rubber and the addition amount of the fiber-shaped resin was changed to 30 parts by mass per 100 parts by mass of the rubber. In the same manner as in Example 1, a substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 2 × 10 ¹⁰ Ωcm, and a durometer hardness of A78 / S was produced.
From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed at an enlargement magnification of 50, a non-fibrous resin island structure was formed in the rubber sea structure. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction).

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 3. The volume resistivity of the semiconductive belt manufactured as described above is 2.5 × 10 ¹⁰ Ωcm, the contact angle of water on the surface of the semiconductive belt is 110 degrees, and the ten-point average surface roughness Rz is It was 8 μm.

<Example 5>
(Formation of substrate)
The same rubber composition was used in Example 1 except that the addition amount of the non-fiber-shaped resin was changed to 50 parts by mass per 100 parts by mass of the rubber and the addition amount of the fiber-shaped resin was changed to 30 parts by mass per 100 parts by mass of the rubber. In the same manner as in Example 1, a substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 3 × 10 ¹⁰ Ωcm, and a durometer hardness of A80 / S was produced.
From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed at an enlargement magnification of 50, a non-fibrous resin island structure was formed in the rubber sea structure. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction).

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 3. The volume resistivity of the semiconductive belt of Example 5 manufactured as described above is 3.5 × 10 ¹⁰ Ωcm, the contact angle of water on the surface of the semiconductive belt is 110 degrees, and the ten-point average surface The roughness Rz was 8 μm.

<Comparative Example 1>
(Formation of substrate)
The same rubber composition was used in Example 1 except that a non-fibrous resin and a fibrous resin were not added, and in the same manner as in Example 1, a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, and a volume resistivity of 1 A base material of × 10 ⁹ Ωcm and durometer hardness A47 / S was produced.

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 3. The volume resistivity of the semiconductive belt of Comparative Example 1 manufactured as described above is 3 × 10 ⁹ Ωcm, the contact angle of water on the surface of the semiconductive belt is 110 degrees, and the ten-point average surface roughness. Rz was 8 μm.

<Comparative example 2>
(Formation of substrate)
The rubber compound 2 described below was used for forming the base material.
= Rubber compound 2 =
Rubber: Chloroprene rubber (Showa Denko-DuPont Co., Ltd .: Neoprene WRT): 80 parts by mass Rubber: Ethylene propylene diene rubber (Sumitomo Rubber Co., Ltd .: Esprene 505A): 20 parts by mass Conductive agent: Acetylene black (Manufactured by Denki Kagaku Kogyo Co., Ltd .: granular acetylene black, volume average particle size 35 nm): 30 parts by mass, vulcanizing agent: powdered sulfur (manufactured by Karuizawa Smelter): 1 part by mass, vulcanization accelerator: di-O Trill guanidine (Ouchi Shinsei Chemical Co., Ltd .: Noxeller DT): 1 part by mass, vulcanization accelerator: Tetramethylthiuram monosulfide (Ouchi Shinsei Chemical Co., Ltd .: Noxeller TS): 1 part by mass, filler: Copper powder (Shodo Chemical Co., Ltd .: Aenka 3 copper): 5 parts by mass

Filler: Magnesium oxide (Kyowa Chemical Co., Ltd .: Magsarat 150ST); 4 parts by mass Filler: Silica powder (Nippon Silica Co., Ltd .: Nipsil VN-3): 5 parts by mass

A base material was formed in the same manner as in Example 1 using the composition of the rubber compounding 2. The obtained base material was placed on the outside of a metal tube, and the surface was polished to obtain a base having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 5 × 10 ⁸ Ωcm, and a durometer hardness of A60 / S. A material was prepared.

(Formation of surface layer)
When the surface layer was formed, the addition amount of the fluororesin was 15 parts by mass, and a film thickness of 20 μm was obtained in the same manner as in Example 1 except that a silane coupling agent (manufactured by Japan Atchison Co., Ltd .: WH-1) was used as the curing agent. A surface layer was formed to produce a semiconductive belt. The volume resistivity of the semiconductive belt thus obtained is 9 × 10 ⁸ Ωcm, the contact angle of water on the surface of the semiconductive belt is 85 degrees, and the ten-point average surface roughness Rz is 1. It was 0 μm.

<Comparative Example 3>
(Formation of substrate)
The rubber compound 3 described below was used for forming the base material.
= Rubber compounding 3 =
Rubber: Acrylonitrile butadiene rubber (manufactured by Nippon Zeon Co., Ltd .: NIPOL DN): 100 parts by mass・ Vulcanizing agent: Sulfur (Tsurumi Chemical Co., Ltd .: 200 mesh): 5 parts by mass ・ Vulcanization accelerator: 2-mercaptobenzothiazole (Ouchi Shinsei Chemical Co., Ltd .: Noxera-M): 1 .5 parts by mass ・ Vulcanization aid: Zinc oxide (manufactured by Hakusuitec Co., Ltd .: R powder, volume average particle size 5 μm): 5 parts by mass ・ Anti-aging agent: 2,2,4-trimethyl-1,2-dihydro Quinoline polymer (Ouchi Shinsei Chemical Co., Ltd .: NOCRACK 224S): 1 part by mass, processing aid: stearic acid: 1 part by mass, plasticizer: bis (2-ethylhexyl) phthalate (Daihachi Chemical Co., Ltd.) : DOP): 10 parts by mass of non-fiber shaped resin: phenol resin (manufactured by Sumitomo Bakelite Co., Ltd .: PR-13349, volume average particle size 200 μm): 40 parts by mass of fiber shaped resin: 1.0 mm in length ( Chopped strand of aramid fiber (fineness: 39 tex) (manufactured by Teijin Techno Products Co., Ltd .: Technora): 30 parts by mass The acrylonitrile content in the acrylonitrile butadiene rubber is 33.5% by mass.

In the same manner as in Example 1, the rubber blend 3 composition was prepared as a substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 4 × 10 ⁸ Ωcm, and a durometer hardness of A90 / S.
From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed at an enlargement magnification of 50, a non-fibrous resin island structure was formed in the rubber sea structure. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction).

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 3. The volume resistivity of the semiconductive belt of Comparative Example 3 manufactured as described above is 9 × 10 ⁸ Ωcm, the contact angle of water on the surface of the semiconductive belt is 110 degrees, and the ten-point average surface roughness. Rz was 5 μm.

<Comparative example 4>
(Formation of substrate)
Except for adding non-fibrous resin and changing the amount of fibrous resin added to 35 parts by mass per 100 parts by mass of rubber, the same rubber composition was used in Example 1, and the same as in Example 1, A substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, a volume resistivity of 3 × 10 ¹⁰ Ωcm, and a durometer hardness of A70 / S was produced.
From the surface of the obtained base material, a 0.1 μm-thick slice was cut out with a microtome (Reichert Co., Ultracut N) equipped with a diamond knife, and a stereomicroscope (Olympus Co., SZX7) was cut out. When observed with a magnification of 50 times, formation of a sea-island structure with rubber and non-fibrous resin was not confirmed. In addition, the long axis of the fiber-shaped resin was oriented in the direction along the surface of the substrate (direction perpendicular to the thickness direction).

(Formation of surface layer)
A surface layer having a thickness of 20 μm was formed in the same manner as in Example 3. The volume resistivity of the semiconductive belt of Comparative Example 3 manufactured as described above is 5 × 10 ¹⁰ Ωcm, the contact angle of water on the surface of the semiconductive belt is 110 degrees, and the ten-point average surface roughness. Rz was 7 μm.

<Evaluation>
For the semiconductive belts obtained in Examples 1 to 5 and Comparative Examples 1 to 4, the tensile stress at 1% elongation, the tensile stress at 3% elongation, the permanent elongation at 3% elongation, and the volume resistivity I asked for variation. Also, the bleeding property of the semiconductive belt and the transfer image quality (blur, holocharacter, color registration) were evaluated. These results are shown in Table 1 together with the hardness of the base material, the volume resistivity, the contact angle of water on the surface of the semiconductive belt, and the surface roughness.

-1% tensile stress at 3% elongation, 3% tensile stress at elongation
The tensile stress of the semiconductive belt is based on JIS K6251 (2004). Three dumbbell-shaped No. 3 test pieces are produced from the produced semiconductive belt by a punching blade mold, and a tensile tester (Strograph VE10D: Toyo) The median value obtained by measuring the tensile stress at 1% elongation and at 3% elongation using Seiki Seisakusho Co., Ltd. was taken as the tensile stress.

Permanent elongation at -3% elongation
The permanent elongation at 3% elongation of the semiconductive belt is 96 when the semiconductive belt is stretched by 3% in an environment of 28 ° C. and 85% RH with respect to the belt circumference before stretching. It calculated | required from the elongation rate of the belt circumference after storing for hours.

-Volume resistivity and volume resistivity variation-
The volume resistivity of the semiconductive belt was measured by the above-mentioned method at 3 points in the length direction of the obtained semiconductive belt and 8 points in the circumferential direction (24 points in total), and the average value was determined as the volume resistivity. It was. Further, the difference between the maximum value and the minimum value of the common logarithm of the volume resistivity was defined as the variation in the volume resistivity of the semiconductive belt.

-Bleedability-
The obtained semiconductive belt was brought into contact with the OPC photoreceptor for 2 weeks under a high temperature and high humidity environment (48 ° C., 90% RH environment), and then the image quality was evaluated using the OPC photoreceptor as follows.
○: There is no problem in the transfer image quality ×: There is a problem in the transfer image quality at the part where the semiconductive belt is in contact (white spots occur)

-Evaluation of transfer image quality-
The obtained semiconductive belt was mounted on an image forming apparatus having the configuration shown in FIG. 3 modified from Docu Color 1255CP of Fuji Xerox Co., Ltd., and the transfer image quality after continuous output of 10,000 sheets was evaluated. An OPC photoconductor was used as the photoconductor, and a spherical toner having a shape factor (SF) 132 and a volume average particle size of 5.5 μm was used as the toner. A4 size J paper (manufactured by Fuji Xerox Office Supply Co.) was used as the paper.

For the volume average particle diameter of the toner, a Coulter counter (TA-II type: manufactured by Beckman-Coulter) was used as a measuring device, and ISOTON-II (Beckman-Coulter) was used as an electrolytic solution.
As a measurement method, 1.0 mg of a measurement sample was added to 2 ml of a 5% aqueous solution of sodium alkylbenzenesulfonate as a dispersant. This was added to 100 ml of the electrolytic solution to prepare an electrolytic solution in which the sample was suspended. The electrolyte in which the sample is suspended is subjected to a dispersion treatment for 1 minute by an ultrasonic disperser, and the particle size distribution of particles in the range of 2 μm to 60 μm is obtained by using the 100 μm diameter aperture as the aperture by the Coulter Counter TA-II type. The volume average particle size was determined by measurement. The measured number of particles is 50000.

[Blur rating]
The occurrence of blur (toner scattering) was evaluated according to the following criteria.
○: No blurring or slight blurring, no problem in image quality ×: Bluring, problem in image quality

[Holo character evaluation]
The occurrence of holocharacters (line image voids) was evaluated according to the following criteria.
○: Occurrence is slight and there are few image quality problems ×: Image quality problems

[Color registration evaluation]
The occurrence of cash register misregistration was evaluated according to the following criteria.
○: Occurrence is slight and there are few image quality problems ×: Image quality problems

  From the results of Table 1, it can be seen that the semiconductive belts of Examples 1 to 5 of the present invention were free from image quality defects and were able to stably obtain excellent image quality over a long period of time. On the other hand, in the semiconductive belts of Comparative Example 1 and Comparative Example 2, color registration misalignment occurred due to the influence of the permanent elongation of the base material and the influence of the micro slip in the continuous paper running test of 10,000 sheets. Further, in the semiconductive belt of Comparative Example 2, a so-called bleed phenomenon was observed in which a low molecular oil component dispersed in the belt base material was deposited on the surface of the semiconductive belt. In the semiconductive belt of Comparative Example 3, since the belt hardness was high, the formation of the transfer nip was insufficient, and image quality defects such as toner scattering (blur) occurred. The semiconductive belt of Comparative Example 4 had a poor permanent elongation because no non-fibrous resin was added, and the substrate broke in the measurement of the permanent elongation at 3% elongation. In addition, the transfer image quality was not durable against continuous paper running, and defects occurred in the image quality on the first 10 prints.

It is sectional drawing which shows the structure of the semiconductive belt of this invention. It is explanatory drawing which shows an example of the image forming apparatus which concerns on this invention. It is explanatory drawing which shows an example of the image forming apparatus which concerns on this invention. 1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to an embodiment. It is a figure which shows the measuring method of volume resistivity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductive belt 2 Surface layer 3 Base material 4b Secondary transfer apparatus 5a Paper conveyance belt 5b Intermediate transfer belts 6a and 6b Image carrier (photosensitive member)
7a, 7b Recording material 8a Transfer device 8b Primary transfer device 9a, 9b Stretch roll 10 Photosensitive drum 11 Charging device 12 Exposure device 13 Rotary developing device 13a Yellow developing device 13b Magenta developing device 13c Cyan developing device 13d Black developing device 17 Cleaning device 20 Intermediate transfer belts 21 to 24 Tension roll 25 Primary transfer roll 26 Cleaning member 30 Secondary transfer roll 40 Recording material 41 Supply tray 42 Pickup roll 43 Registration roll 44 Conveying belt 45 Fixing device 46 Conveying roll 47 Discharging roll 48 Image Forming equipment

Claims (2)

A semiconductive belt having a substrate and a surface layer,
The base material contains rubber, a non-fibrous resin, and a fibrous resin, and the durometer hardness of the base material is in a range of A50 / S to A85 / S,
The semiconductive belt is characterized in that the tensile stress at 3% elongation of the semiconductive belt is in the range of 4 Mpa to 25 MPa, and the permanent elongation at 3% elongation is in the range of 2% or less.   An image forming apparatus comprising the semiconductive belt according to claim 1.

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