JP2007033705A - Semi-conductive belt and image forming apparatus using semi-conductive belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semi-conductive belt having a small permanent elongation rate by having excellent conduction and having large stress during low elongation of an elastic belt, and to provide an image forming apparatus provided with the semi-conductive belt. <P>SOLUTION: The semi-conductive belt forming a surface layer on a base substance contains at least resin particles, a resin-based fiber, and two or more kinds of different carbon blacks in the base substance. In addition, the image forming apparatus is provided 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 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). Have been already provided, or can be directly transferred to a recording material on a semiconductive belt (paper conveying belt). Furthermore, in order to obtain high-quality transfer image quality in recent years, the toner tends to use a small-diameter spherical toner, and the toner is easily moved by a transfer electric field because the toner is reduced in diameter and spherical. Therefore, the problem that the toner scatters easily occurs.

  In this type of intermediate transfer belt (paper conveyance belt), from the viewpoint of maintaining good transfer performance of the image from the image carrier, the nip area between the intermediate transfer belt (paper conveyance belt) and the image carrier, It is necessary to increase the pressure in the nip region between the intermediate transfer belt (paper conveyance belt) and the transfer member sufficiently and to increase the adhesion.

  For this purpose, an intermediate transfer belt (paper conveyance belt) having a belt base material itself formed of an elastic material such as a flexible rubber material has already been provided. However, when a flexible rubber material is used, the stress at low elongation is small and the permanent elongation rate (creep) is large, so the rubber material stretches (deforms) due to belt tension, and color shift over time. There arises a problem that the belt life is shortened.

  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 is molded by a method of winding the yarn (for example, see 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 very unsuitable for mass production because it takes a very long time to wind the yarn around a drum and the cost is high.

  2. Description of the Related Art A rubber belt is known in which a woven fabric is used as an extension stopper for a belt, and an endless belt is formed by applying rubber to the woven fabric. Further, an intermediate transfer member having one or more fiber layers and an elastic layer laminated on one or both surfaces of the fiber layers is disclosed (for example, see Patent Document 2). Further, there has been proposed an intermediate transfer belt having a layer structure of two or more layers including an elastic layer having a core layer inside and an interval between fibers of 50 to 3000 μm and a covering layer (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 disadvantage that image unevenness occurs when used as an intermediate transfer belt.

  As a method for eliminating the disadvantages of these molding methods, there is a method in which carbon black or resin-based fibers are mixed into rubber paste obtained by making acrylic rubber into a paste form with a solvent such as toluene, and then the solvent is removed after molding (for example, (See Patent Document 4). However, this method has a drawback that non-uniform dispersion of resin-based fibers occurs when molding rubber into a paste, and image unevenness occurs when an image is printed. In addition, it takes time to blow off a solvent such as toluene in which rubber is paste-like, which increases costs and is not suitable for mass production. Furthermore, there has been a problem that it is necessary to take measures such as fire prevention by making the rubber into a paste form with a solvent such as toluene.

Further, when an elastic body such as chloropyrene rubber in which carbon black or the like is dispersed is used as a transfer / conveying belt, a semiconductive resistance region at a level of 10 ⁹ Ωcm is a region where resistance control is difficult, and therefore a normal rubber It is almost impossible to stably obtain a desired resistance value by adding ordinary conductive carbon black to the material. It is difficult to stably produce variations in the resistance of elastic belts within one digit (log Ωcm value), and when the in-plane variation in resistance is more than one digit, transfer voltage cannot be applied uniformly, so transfer image quality is low. There is an unstable problem. Further, the belt holds the transfer material, and a transfer voltage of 1 kV to 5 KV is applied to transfer the toner image to the transfer material. This applied voltage changes the resistance value of the belt material, and the transfer material There was a problem that the resistance value changed between a certain part and a part without a transfer material.

  In response to such technical problems, if a mixed base material of chloroprene rubber and EPDM is used as the belt base material of the paper transport belt, excellent ozone resistance and flame retardancy can be exhibited, and the bleed A technique capable of effectively avoiding the phenomenon has already been provided (see, for example, Patent Document 5). In addition, in Patent Document 5, if acetylene black, furnace black and acetylene black, or acetylene black and ketjen black are dispersed in the belt base material, fluctuations in electrical resistance over time can be suppressed. It is also disclosed that this can be done.

However, the conveyor belt has a low stress at low elongation and a large permanent elongation rate (creep), so the rubber material stretches (deforms) due to belt tension, and problems such as color shift over time occur. In addition, the conveyor belt has the same problem as the conventional semiconductive belt. That is, when a filler such as carbon or a metal compound is dispersed in a polymer resin, the resistance variation in the intermediate transfer body due to the dispersed state of the filler is as large as about one digit or more, and the slight difference between the filler and the filler is small. For example, the resistance of the intermediate transfer member may be lowered over time due to dielectric breakdown of a high polymer resin portion or filler rearrangement due to energization. As described above, when the printout is performed, there is a problem that the volume resistivity of the intermediate transfer member is partly or entirely deviated from the range of the good volume resistivity with time and the image quality is deteriorated.
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

  The object of the present invention is to solve the above technical problems. That is, an object of the present invention is to provide a semiconductive belt having good conductivity, a large stress at the time of low elongation of an elastic belt, and a small permanent elongation rate, and an image forming apparatus including the semiconductive belt. And

  The above problems are solved by the present invention described below. That is, the present invention is a semiconductive belt having a surface layer formed on a base material, and the base material contains at least resin particles, resin fibers, and two or more different types of carbon black. A semiconductive belt. Preferred embodiments are as follows.

(1) A 1st aspect is an aspect whose Young's modulus of the said resin fiber is 3-25GPa.
(2) A 2nd aspect is an aspect whose permanent elongation rate at the time of 3% elongation of the said base material is 2% or less.
(3) In the third aspect, among the rubber components in the base material, the relationship between the SP value (SP1) of the main rubber component and the SP value (SP2) of the resin particles is | SP1-SP2 | ≦ 2. This is an embodiment.
(4) In the fourth aspect, 20 to 50 parts by mass of the resin particles, 10 to 30 parts by mass of the resin fiber, and two or more different types of the rubber component in 100 parts by mass of the base material. This is an embodiment in which 20 to 50 parts by mass of carbon black is contained in total.
(5) A fifth aspect is an aspect in which the substrate has a volume resistivity of 1 × 10 8 to 1 × 10 12 Ωcm.
(6) A sixth aspect is an aspect in which the surface layer is a toner release layer.

  The present invention also provides an image forming apparatus comprising the above-described semiconductive belt of the present invention. Preferred embodiments are as follows.

(1) A first aspect includes an image carrier and the semiconductive belt facing the image carrier, and an image formed on the image carrier is transferred to a recording material via the semiconductive belt. It is an aspect.
(2) A second aspect is an aspect in which the semiconductive belt is stretched around a plurality of stretching rolls and is arranged in contact with the drum-shaped image carrier.
(3) A third aspect is an aspect in which the semiconductive belt is used as an intermediate transfer belt.
(4) A fourth aspect is an aspect in which the semiconductive belt is used as a paper transport belt.
(5) A fifth aspect is an aspect in which a spherical toner having a shape factor SF defined by the following formula (1) of 140 to 100 is used.

Formula (1):
SF = [(maximum length of toner particles) ² / (projected area of toner particles)] × π / 4 × 100

  The present invention can provide a semiconductive belt having good conductivity, a large stress at the time of low elongation of the elastic belt, and a low permanent elongation, and an image forming apparatus including the semiconductive belt.

<Semiconductive belt>
The semiconductive belt of the present invention has one or more layers formed on a substrate, and the substrate contains at least resin particles, resin fibers, and two or more different types of carbon black.

  With such a semiconductive belt, for example, an effect is obtained in which the tensile stress at 1% elongation is 2 Mpa or more and the tensile stress at 3% elongation is 4 Mpa or more. And it becomes a semiconductive belt with favorable electroconductivity, the stress at the time of low elongation of an elastic belt being large, and a small permanent elongation rate. Hereinafter, the semiconductive belt of the present invention will be described in detail.

(1) Substrate:
In the base material, at least resin particles, resin fibers, and two or more different types of carbon black are contained in a rubber component that is an elastic material. By containing resin particles and resin fibers, the tensile stress at the time of low elongation can be increased, and the permanent elongation (creep property) can be decreased. Furthermore, the processability can be improved by adding a resin component as a filler, and a semiconductive rubber belt with good mass productivity can be produced.

  In rubber materials, in order to improve the stress at low elongation, a large amount of an insulating inorganic filler such as calcium carbonate, silica, talc, clay, titanium oxide is filled. It is known to add fiber shaped fillers. However, these inorganic fillers have a problem that when the filling amount is increased, the kneading processability and the molding processability are remarkably deteriorated.

  On the other hand, in the present invention, by blending the resin particles, the resin component is melted and reduced in viscosity by heat during kneading. As a result, kneading workability can be improved, and after the resin is cured, the stress increase at low elongation is also good. Even if a rubber material is used, it is possible to satisfy the necessary characteristics of high stress and permanent elongation at low elongation required for the intermediate transfer belt. The tensile stress can be measured using a dumbbell-shaped No. 3 test piece in accordance with JISK6251 with an environment of temperature and humidity of 23 ° C. and 55% RH.

  The semiconductive belt of the present invention preferably has a permanent elongation rate of 2% or less at 3% elongation. The permanent elongation can be determined from the amount of elongation of the belt after it has been stored for 96 hours in an environment of 28 ° C. and 85% RH, with the semiconductive belt extended by 3%.

  At least 20 to 50 parts by mass of resin particles, 10 to 30 parts by mass of resin fibers, and two or more different types of carbon black with respect to 100 parts by mass of a rubber component that is an elastic material constituting the belt base material of the present invention. By adding 20 to 50 parts by mass in total, it is possible to satisfy the above-described required characteristics of high stress at elongation and permanent elongation more reliably.

  The JISA hardness of the elastic material constituting the substrate is preferably 50 to 90 degrees, and more preferably 60 to 80 degrees. If the elastic material has a JIS hardness of less than 50 degrees, the surface elongation due to the nip pressure becomes too large, which may cause problems such as poor transfer image quality. When the JISA hardness exceeds 90 degrees, the flexibility may be reduced, and a nip shape cannot be secured, causing problems such as poor transfer image quality. In addition, JISA hardness can be measured with a polymer measuring instrument Co., Ltd. product durometer type A hardness meter: ASKER A type based on JISK6253 (1997).

  Examples of the resin particles include thermosetting resins such as phenol resins, thermosetting urethane resins, epoxy resins, and reactive monomers, or heat such as polyvinyl chloride (PVC), polyvinyl acetate (PVA), and thermoplastic urethane. A plastic resin is mentioned.

  As specific resin particles, it acts as a softening material during processing, and is crosslinked with rubber after vulcanization to improve hardness, wear resistance, compression resistance, and permanent elongation. For example, PR-13355, PR-12686 (product name) manufactured by Sumitomo Bakelite Co., Ltd., which are phenol resin particles surface-treated with hexamine manufactured by Sumitomo Bakelite Co., Ltd., are preferably used.

  In FIG. 4, the schematic diagram of the vulcanization | cure state by addition of a resin particle is shown. FIG. 4A shows a case where resin particles are not blended, and shows a state in which sulfur is added to the material of the semiconductive belt and added and vulcanized. FIG. 4B shows the state before and after adding sulfur to the semiconductive belt material containing resin particles. As shown in FIG.4 (b), since the crosslinked structure with the resin molecule | numerator of the resin particle is comprised, a crosslinking density becomes large compared with the case of not mix | blending. As a result, the hardness and wear resistance can be improved, and the compression strain and permanent elongation can be reduced.

  20-50 mass parts is preferable with respect to 100 mass parts of rubber components, and, as for the compounding quantity with respect to the rubber component of the said resin particle, 25-45 mass parts is more preferable. Here, when the compounding amount of the resin is less than 20 parts by mass, the amount of the resin is too small, so that the workability is improved, but the physical property value may be deteriorated. On the other hand, if the blending amount of the resin exceeds 50 parts by mass, the characteristics of the resin are excessively exhibited, the characteristics of the rubber are not utilized, and cracks may occur.

  Examples of the resin fibers include resin fibers such as cotton, hemp, silk, rayon, acetate, nylon, acrylic, vinylon, vinylidene, polyester, polystyrene, polypropylene, and aramid.

  Among the resin-based fibers as described above, those having a Young's modulus of 3 to 25 GPa are preferable, and those of 7 to 21 GPa are more preferable. When the Young's modulus is less than 3 GPa, the effect of improving the strength by the fiber may be insufficient, and when it exceeds 25 GPa, problems such as the hardness of the elastic material becoming harder and the strength becoming uneven are generated. There is a case. The Young's modulus can be measured according to ASTM D885 using a yarn obtained by spinning a 50 mm fiber.

  The length of the resin fiber is preferably 0.1 mm to 20 mm, more preferably 0.5 mm to 10 mm, and further preferably 0.6 mm to 6 mm. If the length is less than 0.1 mm, it is difficult to orient the major axis in the direction along the belt surface (perpendicular to the thickness direction). If the length exceeds 20 mm, the major axis is in the belt thickness direction. Bending may occur.

  As a specific resin fiber material, an aramid fiber is preferably used because the fiber shape can be maintained at a heating temperature of 100 ° C. to 160 ° C. during rubber processing. Conex (trade name) manufactured by Teijin Techno Products Ltd., Technora (trade name) fiber length of 0.6 to 6 mm, etc. are preferably used.

  10-30 mass parts is preferable with respect to 100 mass parts of rubber components, and, as for the compounding quantity with respect to the rubber component of the said resin-type fiber, 20-30 mass parts is still more preferable. Here, if the resin fiber is less than 10 parts by mass, sufficient physical properties may not be obtained even when combined with other reinforcing agents, and if it exceeds 30 parts by mass, the processability may be deteriorated and a problem that cannot be molded may occur. .

  In the present invention, examples of the rubber component include diene rubbers and hydrogenated products thereof (for example, NR, IR, hydrogenated NBR, hydrogenated SBR), olefin rubbers (for example, ethylene propylene (EODM, EPM)), Maleic acid-modified ethylene / propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM) ionomer, halogen-containing rubber (for example, Br-IIR, Cl-IIR, isobutylene) Brominated paramethylstyrene copolymer (BIMS), CR, hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), maleic acid modified chlorinated polyethylene (M-CM), silicone rubber ( For example, methyl vinyl silicone rubber, methyl phenyl Nil silicone rubber), containing Iongomu (e.g., Porisufidogomu), fluororubber (for example, vinylidene fluoride rubbers, fluorine-containing vinyl ether rubbers, fluorine-containing phosphazene rubbers), and their alloys thereof.

  When the resin particles are uniformly dispersed in the rubber component, the effect of improving compression strain resistance and permanent elongation is increased. The resin particles are preferably added to a compatible rubber component.

The compatible rubber component is a combination with a rubber component having almost no difference in solubility parameter δ (SP value). Here, the difference in the solubility parameter δ (SP value) is preferably ² J ^1/2 cm ^2/3 or less, for example. Specifically, it is preferable that the SP value (SP1) of the main rubber component and the SP value (SP2) of the resin particles have a relationship of | SP1-SP2 | ≦ 2.0. Here, the main rubber component means the rubber component having the largest content (mass%).

  The solubility parameter δ (SP value) is represented by the following formula (2). In the following formula (2), δ2d, δ2p ′, and δ2h are SP values due to dispersion force, polarity effect, and hydrogen bonding, respectively. In general, the solubility parameter δ (SP value) is a value represented by δ = (E / Vm) 1/2 where E (cal = 4.1868J) and the molecular volume are Vm, where δ is large. It shows that polarity is so large.

Formula (2): δ = δ2d + δ2p ′ + δ2h

  When a phenol resin is used as the resin particles, the SP value of the phenol resin is 11.5. As a rubber material, polyurethane (SP value = 10), chlorinated polyisoprene (SP value = 9.35), NBR ( Rubber components such as SP value = 9.3) and chloropyrene rubber (SP value = 8.71) can be preferably used.

  In the present invention, the carbon black used as the conductive agent is a combination of two different types of carbon black. Carbon black has a property of bonding in a chain form in the rubber component to which carbon black is added, and the resistance value of the rubber component varies depending on the length of the chain bond. If this chain bond is long, the conductivity of the substrate is improved and its resistance value is lowered. On the other hand, if the chain bond is short, the conductivity of the substrate is lowered and the resistance value is increased. That is, when carbon black that forms a long chain bond is added, the amount of carbon black added to develop a desired resistance value can be reduced compared to carbon black that forms a short chain bond, Since the resistance value largely fluctuates due to the change in the addition amount, the above-described variation in the resistance value in the base material cannot be reduced.

  As carbon black, it is also preferable to use two or more types of carbon blacks having different characteristics such as surface characteristics.

  The length of the carbon black chain bond depends on the particle size and surface activity of the individual particles of the carbon black. As an index indicating this, DBP defined in ASTM D2414-6TT is used. (Dibutyl phthalate) has oil absorption. That is, “characteristics” of “two different types of carbon blacks” include DBP oil absorption. This DBP oil absorbency is expressed by whether the DBP amount (ml) absorbed by 100 g of carbon black is large or small. Carbon blacks with higher DBP oil absorption, that is, more oil absorption, are considered to form longer chain bonds.

  If only the carbon black having a high DBP oil-absorbing property is added to the rubber component to adjust the resistance value of the base material, the resistance value changes greatly even if the addition amount is slightly increased or decreased. Therefore, a predetermined resistance value cannot be imparted to the substrate unless the addition amount and dispersion state of carbon black are strictly defined. On the other hand, if only the carbon black having a low DBP oil absorbency is added and the resistance value of the base material is adjusted and used, the carbon black is substantially uniform in the rubber component than the case where only the carbon black having a high DBP oil absorbency is added. Therefore, the ratio of the change in resistance value with the increase / decrease of the addition amount becomes small. However, in order to give a predetermined resistance value to the elastic layer (corresponding to the base material), it is necessary to add a larger amount of carbon black than when adding only carbon black having high DBP oil absorption. As a result, since the blending ratio of carbon black in the rubber component increases, processing becomes difficult because the viscosity becomes high when the rubber component is kneaded with a Banbury mixer, kneader or the like. Moreover, the problem that the obtained base material becomes high hardness may generate | occur | produce. Therefore, it is preferable to use two or more carbon blacks having different DBP oil absorption properties, such as carbon black having high DBP oil absorption property and carbon black having low DBP oil absorption property.

  The two or more types of carbon black added to the substrate may be those having a difference in DBP oil absorption, but if this difference is too small, the result is the same as when one type of carbon black is added. May result. Accordingly, carbon black having a certain difference in DBP oil absorption is preferable, and at least one carbon black having a different DBP oil absorption is a carbon black having a DBP oil absorption of 250 ml / 100 g or more (DBP oil absorption). The carbon black having a high oil absorption is preferably 150 ml / 100 g or less (carbon black having a low DBP oil absorption).

  Further, the DBP oil absorption amount of carbon black having a high DBP oil absorption property is preferably 280 ml / 100 g or more, and the DBP oil absorption amount of carbon black having a low DBP oil absorption property is more preferably 110 ml / 100 g or less.

  In the present invention, as the two or more types of carbon blacks having different DBP oil absorption properties, at least the carbon black having a high DBP oil absorption property and the carbon black having a low DBP oil absorption property may be used. Carbon blacks with different amounts may further be included.

  Specifically, as the carbon black having high DBP oil absorption, for example, HS-500 (manufactured by Asahi Carbon Co., Ltd.) having a DBP oil absorption of 447 ml / 100 g, Ketjen black (Lion Exo (product of Asahi Carbon Co., Ltd.)) And carbon black such as Vulcan XC-72 (manufactured by Cabot Corporation) having a DBP oil absorption amount of 288 ml / 100 g and DBP oil absorption amount of 265 ml / 100 g. Moreover, as carbon black with low DBP oil absorption, Asahi Thermal FT (Asahi Carbon Co., Ltd.) having a DBP oil absorption of 28 ml / 100 g, Asahi Thermal MT (Asahi Carbon Co., Ltd.) having a DBP oil absorption of 35 ml / 100 g are used. ) And the like.

  Generally, carbon black having a higher DBP oil absorption tends to have a smaller primary particle diameter. As the carbon black having a high DBP oil absorption, a carbon black having a primary particle diameter in the range of 5 to 50 nm is used. The carbon black having a low primary particle size is preferably in the range of 20 to 100 nm.

  As a specific example, when the resistance value of the base substrate is adjusted using a mixture of carbon black having high DBP oil absorption (acetylene black, etc.) and carbon black having low DBP oil absorption (thermal black, etc.), the mixing ratio Is preferably in the range of 1: 1 to 1: 8 by mass ratio (mass of carbon black having high DBP oil absorbency: mass of carbon black having low DBP oil absorbency), and in the range of 1: 2 to 1: 6. More preferably, it is more preferably in the range of 1: 2 to 1: 5.

  When the mass of the carbon black with low DBP oil absorbency is less than 1 when the mass of the carbon black with high DBP oil absorbency is 1, not only the resistance value varies greatly, but also by the increase or decrease of the former addition amount, The resistance value of the substrate may change greatly. On the other hand, if it is larger than 8, as described above, the rubber composition at the time of kneading becomes high in viscosity, so that not only the molding of the substrate becomes difficult, but also the hardness of the substrate may be increased. . Thus, the rapid change of the resistance value of a base material can be suppressed by adjusting the mixing ratio of carbon black having different DBP oil absorbency and the blending amount with respect to the rubber material. At the same time, it is possible to form a base material having a small variation in resistance value with a small amount of addition as compared with the case of carbon black alone having a low DBP oil absorption.

  In the present invention, as a compounding agent for the rubber component, in addition to the carbon black, resin particles, and resin fibers, for example, a vulcanizing agent, a vulcanization accelerator, a co-crosslinking agent, an anti-aging agent, a softening agent, and a plasticizer. , Reinforcing agents and fillers.

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

  Examples of the vulcanization accelerator include magnesia (MgO), thiurams such as tetramethylthiuram disulfide, tetraethylene thiuram disulfide, dithiocarbamates such as zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, Examples include thiazoles such as 2-methylcaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfinamide, and other thioureas.

  Examples of the vulcanization aid include known fatty acids such as zinc white, metal oxide stearic acid, and oleic acid.

  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.

  Examples of the antiaging agent include imidazoles such as 2-mercaptobenzimidazole, amines such as phenyl-α-naphthylamine and NN-di-β-naphthyl-P-phenylenediamine, and phenols such as styrenated phenol. Can be mentioned.

  Examples of the softening agent include fatty acids such as stearic acid and paraffin wax. Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, and process oil.

  The base material can be produced by mixing the above-described components 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, all components are mixed in advance with a tumbler, V blender, etc., and uniformly melt-mixed by an extruder. Depending on the shape of the components, two or more types of molten mixtures in these components are used. Alternatively, a method of melt-mixing the remaining components can be used.

(2) Surface layer:
The surface layer formed on the substrate is preferably a toner release layer. As a material used for the toner release layer, a material having a small surface energy such as a fluororesin material and a material including fluororesin particles is used. The surface energy of the surface of the semiconductive belt can be reduced, and dirt is hardly attached to the surface of the semiconductive belt. Contamination of the surface of the toner release semiconductive belt can be effectively prevented.

  Evaporation of the solvent into the air requires no characteristics such as solvent resistance for the base material compared to solvent-based materials by using a material that uses water as the solvent as the toner release layer material Since there is no, there is an advantage such as environmental friendliness. Furthermore, by using a urethane resin as a binder resin material, the urethane resin is composed of a soft segment mainly composed of a long-chain polyol and a hard segment containing an isocyanate compound, so that it is easy to deform the substrate. Can follow. Further, by using a blocked isocyanate compound used as a curing agent, bleeding (bleeding) of the low molecular component of the base material to the surface layer can be suppressed.

  The content of the fluororesin contained in the toner release layer is not particularly limited, but is preferably in the range of 30 to 70 parts by weight and in the range of 40 to 60 parts by weight with respect to 100 parts by weight of the binder resin. More preferably. The toner release layer may also contain other resin components other than the fluororesin. When the content of the fluororesin contained in the toner release layer is less than 30 parts by mass, the surface energy on the surface of the semiconductive belt member becomes large, so that dirt such as toner adhesion is likely to adhere. There is a case. On the other hand, if the amount is more than 70 parts by mass, it may not be possible to incorporate the necessary amount of other necessary components other than the fluororesin into the toner release layer.

  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. You may use these individually or in combination of 2 or more types.

(Surface roughness)
The ten-point average surface roughness Rz of the surface layer in the semiconductive belt member of the present invention is preferably in the range of 1.5 to 9.0 μm, and more preferably in the range of 3.0 to 6.0 μm. preferable. 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 the slight unevenness of discharge due to the unevenness may cause uniform transferability and image quality to deteriorate over time. The ten-point average surface roughness Rz is the surface roughness specified in JIS B0601.

  The ten-point average surface roughness Rz can be measured using a surface roughness measuring instrument or the like. In the present invention, however, a contact-type surface roughness measuring device (in a 23 ° C./55 RH% environment) Surfcom 570A, manufactured by Tokyo Seimitsu Co., Ltd.) was used. When measuring the surface of the semiconductive belt member, the measurement distance was set to 0.8 mm, and the tip of the contact needle was diamond (5 μmR, 90 ° cone). The average value was determined as the ten-point average surface roughness Rz of the semiconductive belt member.

  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 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.

  The contact angle (hereinafter abbreviated as “contact angle”) of the surface layer in the semiconductive belt of the present invention is preferably 90 degrees or more, more preferably 100 degrees or more, and still more preferably. 115 degrees or more. If the contact angle of the surface layer with respect to water is 90 degrees or more, the surface is hardly contaminated, and contamination of the surface of the semiconductive belt member can be effectively prevented. When the contact angle is less than 90 degrees, dirt adheres and accumulates on the surface of the semiconductive belt member, for example, so that a uniform transfer property and image quality can be obtained over time. Decreases. A method for measuring the contact angle will be described later.

(Measurement method of contact angle)
The contact angle can be measured using a goniometer or the like, but in the present invention, water is dropped on the surface of the semiconductive belt member in an environment of 23 ° C. and 55% RH and left for 10 seconds. The contact angle can be measured using a contact angle measuring device CA-X roll type (manufactured by Kyowa Interface Science Co., Ltd.). In addition, the average value at the time of repeating a measurement 3 times by changing a place can be calculated | required as a contact angle of a semiconductive belt member.

The volume resistivity of the semiconductive belt of the present invention is preferably 1 × 10 ⁸ to 1 × 10 ¹² Ωcm, more preferably 1 × 10 ⁹ to 1 × 10 ¹¹ Ωcm. When the volume resistivity is 1 × 10 ⁸ to 1 × 10 ¹² Ωcm, the toner is scattered around the image due to electrostatic repulsion between the toners and the fringe electric field near the image edge (blur). Problems are less likely to occur. 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.

  Here, the volume resistivity can be measured according to JIS K6911 (1995) using a circular electrode (for example, Hiresta UPMCP-450 UR probe manufactured by Dia Instruments). A method for measuring the volume resistivity will be described with reference to FIG. FIG. 3 is a schematic plan view (a) and an XX sectional view (b) showing an example of a circular electrode. The circular electrode shown in FIG. 3 includes a first voltage application electrode A ′ and a second voltage application electrode B ′. The first voltage application electrode A ′ has a cylindrical electrode part C ′ and a cylindrical shape having an inner diameter larger than the outer diameter of the cylindrical electrode part C ′ and surrounding the cylindrical electrode part C ′ at a constant interval. Ring-shaped electrode portion D ′. The semiconductive belt 1 is sandwiched between the cylindrical electrode portion C ′ and ring-shaped electrode portion D ′ and the second voltage application electrode B ′ in the first voltage application electrode A ′, and the first voltage application electrode A ′. The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C ′ and the second voltage application electrode B ′ is measured, and the volume resistance of the semiconductive belt 1 is calculated by the following equation. The rate ρv (Ωcm) can be calculated. Here, in the following formula (3), t represents the thickness of the semiconductive belt 1.

Formula (3): ρv = 19.6 × (V / I) × t

  The semiconductive belt of the present invention as described above has a simple configuration and prevents deterioration in transfer performance due to the elongation (deformation) of the surface even when it is constantly in contact with the image carrier, and can be used for a long time. Stable and good uniform transferability and image quality can be obtained.

<Image forming apparatus>
The image forming apparatus of the present invention includes the above-described semiconductive belt of the present invention. By providing the above-described semiconductive belt of the present invention, high-quality transfer image quality can be stably obtained. The image forming apparatus of the present invention will be described below.

  For example, as shown in FIG. 1, the image forming apparatus of the present invention includes an image carrier 6 and a semiconductive belt 1 facing the image carrier 6, and a toner image formed on the image carrier 6 is semiconductive. Transfer is performed on the recording material 7 ′ on the belt (intermediate transfer belt) 1 or the semiconductive belt (transfer conveyance belt) 1 ′. The above-described semiconductive belt of the present invention is used as the semiconductive belt (transfer conveyance belt or intermediate transfer belt) 1.

  Here, in the embodiment in which the semiconductive belt 1 is used as an intermediate transfer belt, as shown in FIG. 1, the toner image on the image carrier 6 is transferred to the semiconductive belt (intermediate transfer belt) by the primary transfer device 8a. After the primary transfer to the belt 1, the toner image on the semiconductive belt (intermediate transfer belt) 1 is secondarily transferred to the recording material 7 such as paper by the secondary transfer device 8 b.

  On the other hand, in a mode in which the semiconductive belt 1 is used as a transfer conveyance belt (recording material holding belt), as shown in FIG. 1, a recording material 7 ′ is placed on a transfer conveyance belt (recording material holding belt) 1 ′. Then, the toner image on the image carrier 6 is transferred by the transfer device 8 to the recording material 7 ′ on the transfer conveyance belt (recording material holding belt) 1 ′.

  In the image forming apparatus shown in FIG. 1, it is preferable that the semiconductive belt 1 is stretched around a plurality of stretching rolls 9 and is arranged in contact with the drum-shaped image carrier 6.

  According to this aspect, by causing the semiconductive belt 1 to follow the shape of the image carrier 6 as much as possible, discharge due to useless gaps before and after the nip area at the time of transfer is eliminated, and scattering of the toner image is prevented. be able to.

  Further, in the image forming apparatus shown in FIG. 1, it is preferable that one of the image carrier 6 and the semiconductive belt 1 is used as a drive source and the other is driven to rotate.

  By adopting the driving configuration as in this aspect, one of the driving mechanisms can be omitted, and accordingly, the driving cost can be suppressed, and the driving interference between the semiconductive belt 1 and the image carrier 6 can be reduced. Variation factors such as thickness variation of the conductive belt 1 and feed variation in the process direction can be excluded.

  FIG. 2 shows another embodiment of the image forming apparatus of the present invention. The image forming apparatus shown in FIG. 2 has a photoconductive drum 10 and a shape of the photoconductive drum 10 in a certain area on the photoconductive drum 10 in order to transfer a toner image from the photoconductive drum (image carrier) 10. And an intermediate transfer belt 20 in contact with the intermediate transfer belt 20.

  In the present embodiment, it is preferable that the photosensitive drum 10 is provided with a photosensitive layer whose resistance value is reduced by light irradiation. Around the photosensitive drum 10, charging for charging the photosensitive drum 10 is performed. An apparatus 11; an exposure apparatus 12 for writing an electrostatic latent image of each color component (in this example, yellow, magenta, cyan, and black) on the charged photosensitive drum 10; and each color formed on the photosensitive drum 10 A rotary developing device 13 that visualizes the component latent image with each color component toner, the intermediate transfer belt 20, and a cleaning device 17 that cleans residual toner on the photosensitive drum 10 are provided.

  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 a portion 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.

  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, the intermediate transfer belt 20 is stretched around four stretching rolls 21 to 24 and is predetermined along the surface of the photosensitive drum 10 positioned between the rotary developing device 13 and the cleaning device 17. Only the contact region is closely arranged.

  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 an elastic belt as described later, 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.

  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. The secondary transfer bias is applied, and the stretching roll 22 that also serves as a backup roll is grounded.

  In addition, 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 member 26, and the stretching 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 conveyed to a fixing device 45 through a conveyance belt 44. The paper is discharged to a discharge tray 48 through a transport roll 46 and a discharge roll 47. In this embodiment, the intermediate transfer belt 20 is the semiconductive belt of the present invention.

  Next, the operation of such an image forming apparatus will be described. In FIG. 2, when the image forming apparatus starts an image forming operation, each color component toner image on the photoconductive drum 10 is sequentially formed and sequentially transferred onto the intermediate transfer belt 20 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 photoconductor drum 10 and the intermediate transfer belt 20 are always in contact with each other, the bleed phenomenon can be prevented. Therefore, a retract mechanism for separating the photoconductor drum 10 and the intermediate transfer belt 20 is not necessary, and the belt base is not necessary. In accordance with the fact that an inexpensive elastic material can be used as the material 51, it is possible to reduce the cost by eliminating the need for a retract mechanism.

  Furthermore, in this embodiment, since the intermediate transfer belt 20 is driven and rotated by driving the photosensitive drum 10, 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 this embodiment, if a wide transfer nip area between the photosensitive drum 10 and the intermediate transfer belt 20 is secured, the pressure in the transfer nip area can be reduced. The situation where the drum 10 and the intermediate transfer belt 20 are completely in close contact with each other can be avoided more reliably.

  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.

  As described above, when the semiconductive belt of the present invention is incorporated and used as an intermediate transfer belt or a transfer conveyance belt in an image forming apparatus, it is preferable to use a spherical toner. By using spherical toner as the toner, the material constituting the transfer surface has a low surface hardness and high volume resistance, so that high-quality transfer image quality without image quality defects (holocharacter, blur, color registration) can be achieved. Obtainable.

  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 (1).

Formula (1):
SF = [(maximum length of toner particles) ² / (projected area of toner particles)] × (π / 4) × 100

  The maximum length of toner particles and the projected area of the toner particles are measured using a video camera with an optical microscope image of the toner dispersed on a slide glass using a Luzex image analyzer (manufactured by Nireco Corporation, FT). It can be carried out by taking it into a Luzex image analyzer and processing the image.

  The spherical toner contains at least a binder resin and a colorant. The spherical toner may preferably use 2 to 12 μm particles, more preferably 3 to 9 μm particles.

  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, and other inorganic fine particles. Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  Known charge control agents can be used, but 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 The emulsion polymerization aggregation method to obtain a spherical toner by mixing and agglomerating and heat-fusing the solution, a polymerizable monomer for obtaining a binder resin, a colorant, and a release agent, if necessary, a charge control agent 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.

  Further, a manufacturing method may be performed in which the spherical toner obtained by the above method is used as a core, and aggregated particles are further adhered and heat-fused to have 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. 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>
(Preparation of base material)
The following rubber compound 1 was used for the production of the substrate.

"Rubber compound 1"
CR: Neoprene WRT (Showa Denko-DuPont: 80 parts by mass EPDM: Esprene 505A (Sumitomo Rubber): 20 parts by mass Vulcanizing agent: Powder ion (Karuizawa Refinery): 1 part by mass Vulcanization accelerator: Noxeller DT (Ouchi Emerging Chemical): 1 part by mass, vulcanization accelerator: Noxeller TS (Ouchi Emerging Chemical): 1 part by mass, filler: Aenka 3 (Same Chemical): 5 parts by mass, filler: Magsarat 150ST (Kyowa Chemical); 4 parts by mass Filler: Nipsil VM-3 (Nippon Silica): 5 parts by mass Carbon black (1): Granular acetylene black (manufactured by Electrochemical Co., Ltd., DBP oil absorption: 288 ml / 100 g): 10 parts by mass,
Carbon black (2): Asahi Thermal FT (Asahi Carbon Co., Ltd., DBP oil absorption: 28 ml / 100 g): 40 parts by mass Resin particles: phenol resin particles: Sumitomo Bakelite Co., Ltd .: PR-13349: 20 Mass parts / Resin fiber (Aramid fiber; manufactured by Teijin Techno Products Limited: chopped strand length of Cornex fiber 0.6 mm, Young's modulus 8 GPa): 10 parts by mass

  Rubber compounding 1 was kneaded with two rolls as follows. As for the SP value described above, the SP value of the phenol resin was 11.5, and the SP value of the chloropyrene rubber was 8.71.

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. Next, the molded blend rubber material was heated and vulcanized in a vulcanizer with pressurized steam at a temperature of 126 ° C. and a pressure of 1.5 kg / cm ² to form a conductive belt material. The obtained belt material was placed on the outside of a metal tube, and the surface was polished to produce a substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, and a volume resistivity of 2 × 10 ⁸ Ωcm. The rubber material (rubber component) used for the belt body is a rubber having a JIS A hardness of 65 in a sample having a thickness of 12 mm.

(Formation of surface layer)
As a two-component curable water-based urethane resin coating comprising fluororesin particles and carbon black, a water-based urethane resin coating (Emuralon 345: 30 parts by mass of fluorine resin particles and 10 parts by mass of carbon black). Nippon Atchison Co., Ltd.) and blocked isocyanate (WH-2: Nihon Atison Co., Ltd.) as a curing agent are mixed at a blending ratio of 100: 10, and the resulting dispersion is applied to the surface of the resistance layer. After spray coating on the surface of the formed elastic belt, it is heated and dried at 120 ° C. for 15 minutes to form a surface layer of fluorine resin particles, carbon black and urethane resin with a film thickness of 20 μm. Produced.

The volume resistivity of the semiconductive belt of Example 1 manufactured as described above was 5 × 10 ⁸ Ωcm, and the contact angle of the belt surface was 92 degrees, which was obtained as described below. The ten-point average surface roughness Rz was 3 μm.

<Example 2>
(Preparation of base material)
Carbon Black (2): The same rubber as in Example 1 except that the amount of Asahi Thermal FT (Asahi Carbon Co., Ltd.) was changed to 20 parts by mass and the amount of resin fibers was changed to 20 parts by mass. A base material having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, and a volume resistivity of 2 × 10 ⁹ Ωcm was prepared in the same manner as in Example 1 using the blending. The rubber material used for the belt body is a rubber having a JIS A hardness of 67 in a sample having a thickness of 12 mm.

(Formation of surface layer)
A surface layer was formed in the same manner as in Example 1 to produce a semiconductive belt. The volume resistivity of the semiconductive belt of Example 2 manufactured as described above is 3 × 10 ⁹ Ωcm, the contact angle of the belt surface is 92 degrees, and the ten-point average surface roughness Rz is 3 μm. It was.

<Example 3>
(Preparation of base material)
Except for changing the addition amount of the resin-based particles to 30 parts by mass per 100 parts by mass of the rubber component, the same rubber composition was used in Example 1, and in the same manner as in Example 1, the thickness was 0.5 mm, the inner diameter was 140 mm, and the width was A base material having a size of 320 mm and a volume resistivity of 4 × 10 ⁹ Ωcm was produced. The rubber material used for the belt body is a rubber having a JIS A hardness of 69 in a sample having a thickness of 12 mm.

(Formation of surface layer)
As a two-component curable water-based urethane resin paint comprising fluororesin particles and carbon black, a water-based urethane resin paint (Emuralon 345: containing 40 parts by mass of fluorine resin particles and 15 parts by mass of carbon black). Nippon Atchison Co., Ltd.) and blocked isocyanate (WH-2: Nihon Atison Co., Ltd.) as a curing agent are mixed at a blending ratio of 100: 10, and the resulting dispersion is applied to the surface of the resistance layer. After spray coating on the surface of the formed elastic belt, it is heated and dried at 120 ° C. for 15 minutes to form a surface layer of fluorine resin particles, carbon black and urethane resin with a film thickness of 20 μm. Produced.

The volume resistivity of the semiconductive belt of Example 3 manufactured as described above is 6 × 10 ⁸ Ωcm, the contact angle of the belt surface is 105 degrees, and the ten-point average surface roughness Rz is 6 μm. there were.

<Example 4>
(Preparation of base material)
Carbon black (2): Asahi Thermal FT (Asahi Carbon Co., Ltd.) is added in an amount of 20 parts by mass, and resin particles are added in an amount of 30 parts by mass per 100 parts by mass of rubber component. Except that the amount was changed to 30 parts by mass per 100 parts by mass of the rubber component, the same rubber composition was used in Example 1, and in the same manner as in Example 1, the thickness was 0.5 mm, the inner diameter was 140 mm, the width was 320 mm, and the volume resistivity. A substrate of 8 × 10 ⁹ Ωcm was produced. The rubber material used for the belt body is a rubber having a JIS A hardness of 73 in a sample having a thickness of 12 mm.

(Formation of surface layer)
As a two-component curable water-based urethane resin paint comprising fluororesin particles and carbon black, a water-based urethane resin paint (Emuralon 345: 50 mass parts of fluorine resin particles and 15 mass parts of carbon black). Nippon Atchison Co., Ltd.) and blocked isocyanate (WH-2: Nihon Atison Co., Ltd.) as a curing agent were mixed at a blending ratio of 100: 5, and the resulting dispersion was applied to the surface of the resistance layer. After spray coating on the surface of the formed elastic belt, it is heated and dried at 120 ° C. for 15 minutes to form a surface layer of fluorine resin particles, carbon black and urethane resin with a film thickness of 20 μm. Produced.

The volume resistivity of the semiconductive belt of Example 4 manufactured as described above is 1 × 10 ¹⁰ Ωcm, the contact angle of the belt surface is 110 degrees, and the ten-point average surface roughness Rz is 8 μm. there were.

<Example 5>
(Preparation of base material)
Carbon black (2): Asahi Thermal FT (Asahi Carbon Co., Ltd.) is added in an amount of 20 parts by mass, and resin particles are added in an amount of 40 parts by mass per 100 parts by mass of the rubber component. Except that the rubber composition was changed to 30 parts by mass per 100 parts by mass of the rubber component, and the same rubber composition was used in Example 1, and in the same manner as in Example 1, the thickness was 0.5 mm, the inner diameter was 140 mm, the width was 320 mm, and the volume resistivity was 1. A base material of × 10 ¹⁰ Ωcm was produced. The rubber material used for the belt body is a rubber having a JIS A hardness of 80 in a sample having a thickness of 12 mm.

(Formation of surface layer)
A surface layer was formed in the same manner as in Example 4 to produce a semiconductive belt. The volume resistivity of the semiconductive belt of Example 5 manufactured as described above is 2 × 10 ¹⁰ Ωcm, the contact angle of the belt surface is 110 degrees, and the ten-point average surface roughness Rz is 8 μm. there were.

<Example 6>
(Preparation of base material)
Carbon black (2): Asahi Thermal FT (Asahi Carbon Co., Ltd.) is added in an amount of 20 parts by mass, and resin particles are added in an amount of 50 parts by mass per 100 parts by mass of rubber component. Except that the rubber composition was changed to 30 parts by mass per 100 parts by mass of the rubber component, and the same rubber composition was used in Example 2, and in the same manner as in Example 1, the thickness was 0.5 mm, the inner diameter was 140 mm, the width was 320 mm, and the volume resistivity was 2. A base material of × 10 ¹⁰ Ωcm was produced. The rubber material used for the belt body is a rubber having a JIS A hardness of 82 in a sample having a thickness of 12 mm.

(Formation of surface layer)
A surface layer was formed in the same manner as in Example 4 to produce a semiconductive belt. The volume resistivity of the semiconductive belt of Example 6 manufactured as described above is 3 × 10 ¹⁰ Ωcm, the contact angle of the belt surface is 110 degrees, and the ten-point average surface roughness Rz is 8 μm. there were.

<Example 7>
(Preparation of base material)
Carbon black (2): Asahi Thermal FT (Asahi Carbon Co., Ltd.) is added in an amount of 20 parts by mass, and resin particles are added in an amount of 50 parts by mass per 100 parts by mass of rubber component. Except for using a fiber (manufactured by Teijin Techno Products Co., Ltd .: Technora (trade name) chopped strand length 1 mm, Young's modulus 20 GPa), the amount of resin fiber added was changed to 20 parts by mass per 100 parts by mass of the rubber component. The same rubber composition was used in Example 1, and a substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, and a volume resistivity of 2 × 10 ¹⁰ Ωcm was produced in the same manner as in Example 1. The rubber material used for the belt body is a rubber having a JIS A hardness of 87 in a sample having a thickness of 12 mm.

(Formation of surface layer)
A surface layer was formed in the same manner as in Example 4 to produce a semiconductive belt. The volume resistivity of the semiconductive belt of Example 7 manufactured as described above is 3 × 10 ¹⁰ Ωcm, the contact angle of the belt surface is 110 degrees, and the ten-point average surface roughness Rz is 7 μm. there were.

<Comparative Example 1>
(Preparation of base material)
"Rubber compound 2"
-Epichlorohydrin rubber (1): 70 parts by mass-Acrylonitrile butadiene rubber (2): 30 parts by mass-Vulcanizing agent: 5 parts by mass of sulfur (200 mesh manufactured by Tsurumi Chemical Co., Ltd.)-Vulcanization accelerator (Emerging Ouchi) Chemical Industry Co., Ltd., Noxera-M): 1.5 parts by mass Vulcanization aid: Zinc oxide: 5 parts by mass As anti-aging agent Product name: NOCRACK 224S (manufactured by Kawaguchi Chemical): 1 part by mass, processing aid : Stearic acid: 1 part by massPlasticizer: DOP (Daihachi Chemical): 10 parts by mass

Using rubber compounding 2, a substrate having a thickness of 0.5 mm, an inner diameter of 140 mm, a width of 320 mm, and a volume resistivity of 1 × 10 ⁹ Ωcm was produced in the same manner as in Example 1. The rubber material used for the belt body is a rubber having a JIS A hardness of 47 in a sample having a thickness of 12 mm.

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

<Comparative example 2>
(Preparation of base material)
As a base material, carbon black (1): granular acetylene black is 30 parts by mass, carbon black (2): Asahi Thermal FT (Asahi Carbon Co., Ltd.) is added, resin particles are not added, resin The same rubber composition was used in Example 1 except that the addition of the system fiber was not used. In the same manner as in Example 1, the thickness was 0.5 mm, the inner diameter was 140 mm, the width was 320 mm, and the volume resistivity was 5 × 10 ⁸ Ωcm. A base material was prepared. The rubber material used for the belt body is a rubber having a JIS A hardness of 60 in a sample having a thickness of 12 mm.

(Formation of surface layer)
A semiconductive belt was produced in the same manner as in Example 1 except that the amount of the fluororesin was 15 parts by mass and the silane coupling agent was used as the curing agent when forming the surface layer. The volume resistivity of the semiconductive belt of Comparative Example 2 thus obtained is 9 × 10 ⁸ Ωcm, the contact angle of the surface is 85 degrees, and the ten-point average surface roughness Rz is 1.0 μm. there were.

<Evaluation>
About the semiconductive belts obtained in Examples 1 to 7 and Comparative Examples 1 and 2, the tensile stress at 1% elongation of the substrate, the tensile stress at 3% elongation, the permanent elongation at 3% elongation, the hardness The volume resistivity and the variation in volume resistivity were determined. As a semiconductive belt, the contact angle of water, the surface roughness, the presence or absence of bleed, and the transfer image quality (blur, holo character, color registration) were evaluated. The results are shown in Table 1 below. The evaluation method is as follows.

1) Tensile stress at 1% elongation, 3% tensile stress:
The tensile stress was determined in accordance with JISK6251 using a dumbbell-shaped No. 3 test piece, 23 ° C., 55% RH, and 1% elongation and 3% elongation.

2) Permanent elongation at 3% elongation (creep property):
The semiconductive rubber belt has a permanent elongation at 2% elongation of 2% or less. The permanent elongation was determined from the amount of elongation of the belt after stretching the semiconductive belt at an elongation of 3% and storing it for 96 hours in an environment of 28 ° C. and 85% RH.

3) Hardness:
The JIS-A hardness was measured using a durometer type A ASKER A type manufactured by Kobunshi Keiki Co., Ltd. according to JIS K 6253 (1997). Further, a sample having a sheet thickness of 6 mm was used for the measurement.

4) Volume resistivity, variation in volume resistivity:
Volume resistivity was measured by the following method at 3 points in the length direction of the produced belt and 8 points in the circumferential direction (24 points in total). First, the volume resistivity is measured at the first voltage application electrode A ′ at 22 ° C. and 55% RH using the circular electrode shown in FIG. 3 (Hiresta UPMCP-450 UR probe manufactured by Dia Instruments Co., Ltd.). A current I (A) that flows when a voltage of 100 (V) is applied between the cylindrical electrode portion C ′ and the second voltage application electrode B ′ is measured 10 seconds after the voltage application, and the current I (A ), The volume resistivity ρv (Ωcm) of the semiconductive belt was calculated by the above-described equation (3). Then, the difference between the maximum value and the minimum value of the common logarithm of the volume resistivity at each of 24 points was defined as the variation in volume resistivity, and the average value of the volume resistivity measured at 24 points was defined as the volume resistivity of the belt.

5) Water contact angle:
The contact angle can be measured using a goniometer or the like, but in the present invention, water is dropped on the surface of the semiconductive belt member in an environment of 23 ° C. and 55% RH and left for 10 seconds. The contact angle was measured using a contact angle measuring device CA-X roll type (manufactured by Kyowa Interface Science Co., Ltd.). The average value when the measurement was repeated three times at different locations was obtained as the contact angle of the belt.

6) Measuring method of ten-point average surface roughness (Rz):
For the ten-point average surface roughness (Rz), a contact type surface roughness measuring device (Surfcom 570A, manufactured by Tokyo Seimitsu Co., Ltd.) was used in an environment of 23 ° C. and 55 RH% in accordance with JISB601-1994. When measuring the surface of the semiconductive belt member, the measurement distance was 2.5 mm, the tip of the contact needle was diamond (5 μmR, 90 ° cone), and the measurement was repeated three times at different locations. The average value was determined as the ten-point average surface roughness Rz of the belt member.

7) Bleedability:
The obtained semiconductive belt was brought into contact with the OPC photoreceptor for 2 weeks in a high-temperature and high-humidity environment (48 ° C., 90% RH), and image quality evaluation was evaluated using the OPC photoreceptor.
The judgment was as follows.
○: No problem in transfer image quality.
X: There is a problem in the transfer image quality at the portion where the semiconductive belt is in contact (whiteout occurs).

(Evaluation of transfer image quality)
The obtained semiconductive belt was modified from Fuji Xerox Co., Ltd. Docu Color 1255CP and mounted on the image forming apparatus having the configuration shown in FIG. 2 to evaluate the transfer image quality. An OPC photoconductor was used as the photoconductor.

(Blur evaluation)
The occurrence of blur was evaluated according to the following criteria.
○: No blurring or blurring is slight and there is no problem in image quality.
X: Blur occurs and there is a problem in image quality.

(Holo character evaluation)
The occurrence of holo-characters was evaluated according to the following criteria.
○: Occurrence is slight and there are few image quality problems.
×: There is a problem in image quality.

(Color register)
A continuous running test was performed on 10,000 sheets of A4 size J paper, and the occurrence of color registration was evaluated according to the following criteria.
○: Occurrence is slight and there are few image quality problems.
×: There is a problem in image quality.

  From the results of Table 1, the semiconductive belts of Examples 1 to 7 of the present invention were free from image quality defects and could stably obtain excellent image quality over a long period of time. On the other hand, in Comparative Examples 1 and 2, color registration misalignment occurred due to permanent elongation of the base material in the continuous paper running test of 10,000 sheets. Further, in Comparative Example 2, a so-called bleed phenomenon occurred in which the low molecular oil component dispersed in the belt base material was deposited on the surface of the semiconductive belt.

  From the above, the embodiment according to the present invention is excellent in forming a nip shape at the transfer portion, and there are extremely few image quality defects such as a hollow image (holocharacter) and toner scattering (blur) in the transfer image quality. There was little change in electrical resistance. It was found that the image forming apparatus provided with the semiconductive belt can stably obtain a high-quality transfer image quality.

1 is an explanatory diagram showing an outline of an image forming apparatus according to the present 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, (a) is a top view, (b) is XX sectional drawing. It is a schematic diagram of the vulcanization | cure state by addition of a resin particle, (a) shows the case where a resin particle is not mix | blended, (b) shows the case where a resin particle is mix | blended.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 '... Semiconductive belt 6 ... Image carrier 7, 7' ... Recording material 8 ... Transfer device 8a ... Primary transfer device 8b ... Secondary transfer device 9 ... Stretching roll

Claims (2)

A semiconductive belt having a surface layer formed on a substrate,
A semiconductive belt characterized in that the base material contains at least resin particles, resin fibers, and two or more different types of carbon black.   An image forming apparatus comprising the semiconductive belt according to claim 1.

Images