JP6850094B2 - Conductive rolls for electrophotographic equipment - Google Patents

Description

The present invention relates to a conductive roll for an electrophotographic apparatus that is suitably used in an electrophotographic apparatus such as a copier, a printer, and a facsimile that employs an electrophotographic method.

In electrophotographic equipment, as a method for charging the surface of a photosensitive drum, a contact charging method in which a charging roll is brought into direct contact with the surface of the photosensitive drum is known. As a method of charging the charging roll, a direct current (DC) voltage application method is known from the viewpoint of making the device compact and reducing the cost. In the contact charging method, if the discharge region is narrow, charging may be concentrated locally and image defects may occur. Therefore, for example, as described in Patent Document 1, the discharge region is secured and the charge amount is maintained by adding particles to the surface layer of the charging roll to provide irregularities on the surface.

JP-A-2009-175427

Machine bias may fluctuate due to environmental changes and durability. Along with this, the amount of charge also changes. If the amount of charge is not sufficiently secured, the image may be deteriorated when the amount of charge decreases. It is possible to increase the power supply to stabilize the charge, but there are problems such as the machine becoming larger and the price increasing.

An object to be solved by the present invention is to provide a conductive roll for an electrophotographic apparatus capable of realizing stable charging even at a low applied voltage.

In order to solve the above problems, the conductive roll for electrophotographic equipment according to the present invention includes a shaft body, an elastic body layer formed on the outer periphery of the shaft body, and a surface layer formed on the outer periphery of the elastic body layer. The surface layer is composed of an aggregate of a plurality of particles having an average particle size of 20 to 90% with respect to the thickness of the surface layer, and each particle is bonded at a mutual contact portion and between the particles. The gist is that voids are formed and the voids between the particles make the particles porous.

The thickness of the surface layer is preferably in the range of 5 to 30 μm. It is preferable that each of the particles is bonded and bonded at a contact portion with each other by a binder. In this case, the content of the binder is preferably in the range of 0.1 to 10 parts by mass per 100 parts by mass of the plurality of particles. Each of the particles may be bonded at a mutual contact portion by a chemical bond. In this case, the binder may not be included. The conductive roll for electrophotographic equipment according to the present invention can be used as a charging roll.

According to the conductive roll for electrophotographic equipment according to the present invention, the surface layer is porous due to the voids between the particles, and the amount of discharge is large due to uniform discharge, so that stable charging is realized even at a low applied voltage. can do.

At this time, if the thickness of the surface layer is within the above-mentioned specific range, it is easy to secure the discharge region and the decrease in charge can be suppressed. Then, when the particles are bonded and bonded at the mutual contact portion by a binder, the durability is improved. In this case, when the content of the binder is within the above-mentioned specific range, excellent durability can be ensured while sufficiently securing voids between the particles. Then, when the particles are bonded at the mutual contact portion by a chemical bond, the durability is improved. Moreover, since it is not necessary to contain a binder, it is easy to secure voids between particles.

It is a schematic appearance diagram (a) of the conductive roll for electrophotographic equipment which concerns on one Embodiment of this invention, and the sectional view (b) of the line AA. It is an enlarged schematic view near the surface of the conductive roll for electrophotographic equipment shown in FIG. It is an SEM photograph of the surface of Example 1.

The conductive roll for electrophotographic equipment (hereinafter, may be simply referred to as a conductive roll) according to the present invention will be described in detail. FIG. 1 is a schematic external view (a) of a conductive roll for an electrophotographic apparatus according to an embodiment of the present invention, and a sectional view (b) taken along the line AA. FIG. 2 is an enlarged schematic view of the vicinity of the surface of the conductive roll for electrophotographic equipment shown in FIG.

The conductive roll 10 includes a shaft body 12, an elastic body layer 14 formed on the outer periphery of the shaft body 12, and a surface layer 16 formed on the outer periphery of the elastic body layer 14. The elastic layer 14 is a layer that is a base of the conductive roll 10. The surface layer 16 is a layer that appears on the surface of the conductive roll 10.

The surface layer 16 is composed of an aggregate of a plurality of particles 18. The plurality of particles 18 have an average particle size of 20 to 90% with respect to the thickness of the surface layer 16. The particles 18 are joined at mutual contact portions, and voids 20 are formed between the particles 18. The surface layer 16 is made porous by the voids 20 between the particles 18. The void 20 preferably leads from the surface of the elastic body layer 14 to the surface of the surface layer 16 in the thickness direction.

If the average particle size of the particles 18 is less than 20% of the thickness of the surface layer 16, the voids 20 become smaller and the chargeability is lowered, so that stable charging cannot be realized at a low applied voltage. If the average particle size of the particles 18 is more than 90% of the thickness of the surface layer 16, the voids 20 become smaller and the chargeability is lowered, so that stable charging cannot be realized at a low applied voltage. The average particle size of the particles 18 is more preferably in the range of 30 to 80% with respect to the thickness of the surface layer 16. The average particle size of the particles 18 is a median size measured by a laser diffraction / scattering type particle size distribution measuring device. The plurality of particles 18 constituting the surface layer 16 may have the same particle size or may include particles having different particle sizes. The average particle size of the particles 18 is preferably 30 μm or less from the suitable thickness range of the surface layer 16. Further, it is preferably 3 μm or more.

The particle 18 preferably has a relatively narrow particle size distribution. For example, there is a risk that relatively small particles 18 may enter the voids 20 formed by the relatively large particles 18 to make the voids 20 smaller. Further, when the particles 18 having relatively uniform sizes are used, it is easy to form uniform voids 20. The shape of the particles 18 is not particularly limited, and any particles such as spherical and amorphous may be used as long as voids 20 are likely to be formed between the particles 18 in an aggregated state. A spherical shape is more preferable because a uniform void 20 is likely to be formed.

The particles 18 are composed of resin particles, inorganic particles, and the like. As the particles 18, resin particles are preferable because they are excellent in flexibility and the like. Examples of the resin particles include acrylic particles, urethane particles, and polyamide particles. Of these, acrylic particles are preferable from the viewpoint of low settling property due to low deformation rate. Further, urethane particles are preferable from the viewpoint of being able to have a reactive group. When the particles have a reactive group, the particles 18 can be bonded by a chemical bond without a binder when the surface layer 16 is formed. The resin particles may be a thermoplastic resin, a thermosetting resin, or a crosslinked resin. Examples of the inorganic particles include ceramic particles and metal particles.

The particles 18 may have conductivity or may not have conductivity. In the case of resin particles, conductivity can be obtained by blending a conductive agent in the material constituting the particles 18. Examples of the conductive agent include an ionic conductive agent (quaternary ammonium salt and the like) and an electronic conductive agent (carbon black and the like). The conductive particles are those having a volume resistivity of 10 × 10 ¹² Ω · cm or less.

Binders may or may not be used for bonding the particles 18 to each other. When a binder is used, the particles 18 can be reliably bonded to each other. On the other hand, if a binder is not used, it is possible to prevent the binder from reducing the size of the voids 20 between the particles 18.

The binder is not particularly limited, and a suitable material may be selected according to the required characteristics and the like. Examples of the binder include acrylic resin, methacrylic resin, fluorine resin, silicone resin, polycarbonate resin, urethane resin, polyamide resin and the like. These may be used individually as a binder for the surface layer 16, or may be used in combination of two or more. As the binder, a fluororesin is particularly preferable from the viewpoint of being excellent in low adhesion of an external additive or the like. In addition, it is also preferable to use a binder made of the same material as the particles 18 from the viewpoint of joining the particles 18 to each other.

The content of the binder is preferably in the range of 0.1 to 10 parts by mass per 100 parts by mass of the plurality of particles 18. More preferably, it is in the range of 0.5 to 7 parts by mass, and further preferably in the range of 1.0 to 5 parts by mass, per 100 parts by mass of the plurality of particles 18. When the content of the binder is within the above-mentioned specific range, excellent durability can be ensured while sufficiently securing the voids 20 between the particles 18.

Examples of the bonding between the particles 18 that can be performed without using a binder include bonding by fusion of the particles 18 and bonding by chemical bonding between the particles 18. Bonding by fusion of the particles 18 can be performed using the particles 18 made of a thermoplastic resin. Bonding of the particles 18 by chemical bonds can be carried out by using the particles 18 having a reactive group or by irradiating the resin particles with an electron beam. In addition, these joining methods may be performed even when a binder is used.

The surface layer 16 may or may not contain additives in addition to the particles 18 or in addition to the particles 18 and the binder. Examples of the additive include a conductive agent, a stabilizer, an ultraviolet absorber, a lubricant, a mold release agent, a dye, a pigment, a flame retardant and the like. Examples of the conductive agent include an ionic conductive agent (quaternary ammonium salt and the like) and an electronic conductive agent (carbon black and the like).

The surface layer 16 can be adjusted to a predetermined volume resistivity by adjusting the material type, the composition of the conductive agent, and the like. The volume resistivity of the surface layer 16 may be appropriately set in the range of ^{10 5} to 10 ¹¹ Ω · cm, 10 ⁸ to ^{10 10 Ω · cm, etc., depending on the intended use.}

The thickness of the surface layer 16 is preferably in the range of 5 to 30 μm. More preferably, it is in the range of 10 to 20 μm. When the thickness of the surface layer is within the above-mentioned specific range, it is easy to secure a discharge region, and a decrease in charge can be suppressed. The thickness of the surface layer 16 can be measured by observing the cross section using a laser microscope (for example, manufactured by KEYENCE, "VK-9510", etc.). For example, the distances from the surface of the elastic layer 14 to the vertices of the particles 18 appearing on the surface of the surface layer 16 can be measured at five arbitrary positions and expressed by the average thereof.

The surface layer 16 can be formed by using a surface layer forming composition containing a plurality of particles 18 and applying the composition to the outer peripheral surface of the elastic body layer 14 and appropriately performing a drying treatment or the like. In the surface layer forming composition, the plurality of particles 18 can be prepared as a dispersion liquid using a dispersion medium. Examples of the dispersion medium include ketone solvents such as methyl ethyl ketone (MEK) and methyl isobutyl ketone, alcohol solvents such as isopropyl alcohol (IPA), methanol and ethanol, hydrocarbon solvents such as hexane and toluene, ethyl acetate and butyl acetate and the like. Examples thereof include acetic acid-based solvents, diethyl ether, ether-based solvents such as methanol, and water.

The elastic layer 14 contains a crosslinked rubber. The elastic layer 14 is formed of a conductive rubber composition containing uncrosslinked rubber. The crosslinked rubber is obtained by crosslinking the uncrosslinked rubber. The uncrosslinked rubber may be polar rubber or non-polar rubber. Polar rubber is more preferable as the uncrosslinked rubber from the viewpoint of excellent conductivity and the like.

The polar rubber is a rubber having a polar group, and examples of the polar group include a chloro group, a nitrile group, a carboxyl group, and an epoxy group. Specific examples of the polar rubber include hydrin rubber, nitrile rubber (NBR), urethane rubber (U), acrylic rubber (copolymer of acrylic acid ester and 2-chloroethyl vinyl ether, ACM), and chloroprene rubber (CR). , Eoxidized natural rubber (ENR) and the like. Among the polar rubbers, hydrin rubber and nitrile rubber (NBR) are more preferable from the viewpoint that the volume resistivity tends to be particularly low.

Hydrin rubber includes epichlorohydrin homopolymer (CO), epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-allyl glycidyl ether binary copolymer (GCO), and epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary. Copolymers (GECO) and the like can be mentioned.

Examples of the urethane rubber include a polyether type urethane rubber having an ether bond in the molecule. The polyether type urethane rubber can be produced by reacting a polyether having hydroxyl groups at both ends with a diisocyanate. The polyether is not particularly limited, and examples thereof include polyethylene glycol and polypropylene glycol. The diisocyanate is not particularly limited, and examples thereof include tolylene diisocyanate and diphenylmethane diisocyanate.

Examples of the non-polar rubber include isoprene rubber (IR), natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR).

Examples of the cross-linking agent include a sulfur cross-linking agent, a peroxide cross-linking agent, and a dechlorination cross-linking agent. These cross-linking agents may be used alone or in combination of two or more.

Examples of the sulfur cross-linking agent include conventionally known sulfur cross-linking agents such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, sulfur chloride, thiuram-based sulfide accelerator, and high molecular weight polysulfide. it can.

Examples of the peroxide cross-linking agent include conventionally known peroxide cross-linking agents such as peroxyketal, dialkyl peroxide, peroxyester, ketone peroxide, peroxydicarbonate, diacyl peroxide, and hydroperoxide. Can be done.

Examples of the dechlorination cross-linking agent include dithiocarbonate compounds. More specifically, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, 5,8-dimethylquinoxaline-2,3- Dithiocarbonate and the like can be mentioned.

The amount of the cross-linking agent to be blended is preferably in the range of 0.1 to 2 parts by mass, more preferably 0.3 to 1.8 parts by mass with respect to 100 parts by mass of the uncrosslinked rubber from the viewpoint of being difficult to bleed. It is within the range of parts, more preferably within the range of 0.5 to 1.5 parts by mass.

When a dechlorination cross-linking agent is used as the cross-linking agent, a dechlorination cross-linking accelerator may be used in combination. Examples of the dechlorination cross-linking accelerator include 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter abbreviated as DBU) or a weak acid salt thereof. The dechlorination cross-linking accelerator may be used in the form of DBU, but it is preferably used in the form of its weak acid salt from the viewpoint of its handling. Weak salts of DBU include carbonate, stearate, 2-ethylhexylate, benzoate, salicylate, 3-hydroxy-2-naphthoate, phenolic resin salt, 2-mercaptobenzothiazole salt, 2- Examples thereof include mercaptobenzimidazole salt.

The content of the dechlorination crosslinking accelerator is preferably in the range of 0.1 to 2 parts by mass with respect to 100 parts by mass of the uncrosslinked rubber from the viewpoint of being difficult to bleed. It is more preferably in the range of 0.3 to 1.8 parts by mass, and further preferably in the range of 0.5 to 1.5 parts by mass.

In order to impart conductivity to the elastic layer 14, carbon black, graphite, c-TiO ₂ , c-ZnO, c-SnO ₂ (c- means conductivity), an ionic conductive agent (class 4). Conventionally known conductive agents such as ammonium salts, borates, surfactants, etc. can be appropriately added. In addition, various additives may be added as appropriate, if necessary. Additives include lubricants, vulcanization accelerators, anti-aging agents, light stabilizers, viscosity modifiers, processing aids, flame retardants, plasticizers, foaming agents, fillers, dispersants, defoamers, pigments, and release agents. Molds and the like can be mentioned.

The elastic body layer 14 can be adjusted to a predetermined volume resistivity by the type of crosslinked rubber, the blending amount of the ionic conductive agent, the blending of the electronic conductive agent, and the like. The volume resistivity of the elastic layer 14 may be appropriately set in the range of ^{10 2} to 10 ¹⁰ Ω · cm, 10 ³ to 10 ⁹ Ω · cm, 10 ⁴ to 10 ^{8 Ω · cm, etc., depending on the application and the like.} ..

The thickness of the elastic layer 14 is not particularly limited, and may be appropriately set within the range of 0.1 to 10 mm depending on the intended use.

The elastic layer 14 can be manufactured, for example, as follows. First, the shaft body 12 is coaxially installed in the hollow portion of the roll molding die, an uncrosslinked conductive rubber composition is injected, heated and cured (crosslinked), and then demolded or demolded. An elastic body layer 14 is formed on the outer periphery of the shaft body 12 by extrusion molding an uncrosslinked conductive rubber composition on the surface of the shaft body 12.

The shaft body 12 is not particularly limited as long as it has conductivity. Specifically, a metal core such as iron, stainless steel, and aluminum, a core metal made of a hollow body, and the like can be exemplified. If necessary, an adhesive, a primer, or the like may be applied to the surface of the shaft body 12. That is, the elastic body layer 14 may be adhered to the shaft body 12 via an adhesive layer (primer layer). The adhesive, primer, etc. may be conductive if necessary.

According to the conductive roll 10 having the above configuration, the surface layer 16 is made porous by the voids 20 between the particles 18, and the discharge amount is large due to the uniform discharge, so that stable charging is realized even at a low applied voltage. can do. Durability is improved when each particle 18 is bonded and bonded at a contact portion with each other by a binder. In this case, when the content of the binder is within the above-mentioned specific range, excellent durability can be ensured while sufficiently securing the voids 20 between the particles 18. Then, when each particle 18 is bonded at a mutual contact portion by a chemical bond, the durability is improved. Further, since it does not have to contain a binder, it is easy to secure the voids 20 between the particles 18.

The configuration of the conductive roll according to the present invention is not limited to the configuration shown in FIG. For example, in the conductive roll 10 shown in FIG. 1, another elastic body layer may be provided between the shaft body 12 and the elastic body layer 14. In this case, the other elastic layer is a layer that is the base of the conductive roll, and the elastic layer 14 functions as a resistance adjusting layer that adjusts the resistance of the conductive roll. The other elastic body layer can be composed of, for example, any of the materials listed as the materials constituting the elastic body layer 14. Further, for example, in the conductive roll 10 shown in FIG. 1, another elastic body layer may be provided between the elastic body layer 14 and the surface layer 16. In this case, the elastic layer 14 is the base layer of the conductive roll, and the other elastic layer functions as a resistance adjusting layer for adjusting the resistance of the conductive roll.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

(Examples 1 to 6, Comparative Example 1)
<Preparation of conductive rubber composition>
With respect to 100 parts by mass of isoprene rubber, 30 parts by mass of carbon black, 6 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1 part by mass of sulfur, 0.5 parts by mass of thiazole-based vulcanization accelerator, 0 parts by mass of tyraum-based vulcanization accelerator. A conductive rubber composition was prepared by blending 5 parts by mass and 50 parts by mass of heavy calcium carbonate and kneading for 10 minutes using a closed mixer whose temperature was adjusted to 50 ° C.

The following materials were prepared as materials for the conductive rubber composition.
-Rubber component isoprene rubber (IR) [manufactured by JSR Corporation, "JSR IR2200"]
-Conducting agent Carbon black (electronic conductive agent) [Manufactured by Cabot Japan Co., Ltd., "Show Black N762"]
・ Zinc oxide [manufactured by Sakai Chemical Industry Co., Ltd., "2 types of zinc oxide"]
・ Stearic acid [NOF CORPORATION, "Stearic acid Sakura"]
・ Sulfur ["Powdered sulfur" manufactured by Tsurumi Chemical Industry Co., Ltd.]
-Vulcanization accelerator Thiazole-based vulcanization accelerator [manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., "Noxeller DM"]
Thiram-based vulcanization accelerator [manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., "Noxeller TRA"]
-Inorganic filler particles Heavy calcium carbonate [manufactured by Shiraishi Calcium Co., Ltd., "Whiten B", average particle size 3.6 μm]

<Preparation of elastic layer>
The prepared conductive rubber composition was extruded into a crown shape on the outer circumference of a core metal having a diameter of 6 mm and made of free-cutting steel (SUM) using an extrusion molding device. Specifically, by supplying the conductive rubber composition to the gap between the die and the core metal while passing the core metal through the circular mouth portion of the die of the extrusion molding apparatus, the outer circumference of the core metal is elastic. The body layer was extruded. During this extrusion molding, the shape of the elastic layer precursor was made into a crown shape by changing the passing speed of the core metal and controlling the amount of the conductive rubber composition adhered to the core metal in the longitudinal direction. Then, this was heat-treated at 180 ° C. for 30 minutes. As a result, a predetermined elastic body layer (thickness 1.5 mm) was formed on the outer circumference of the core metal.

<Preparation of surface layer>
Particles and a binder were blended so as to have the blending amount (parts by mass) shown in Table 1, 200 parts by mass of methyl ethyl ketone (MEK) was added, and the mixture was mixed and stirred to prepare a liquid composition for forming a surface layer. Next, this liquid composition was roll-coated on the outer peripheral surface of the elastic body layer and heat-treated to form a surface layer having a thickness of 5 to 30 μm on the outer peripheral surface of the elastic body layer. As a result, a conductive roll was produced.

The materials used as the surface layer material are as follows.
-Particle <1>: Acrylic particles, average particle diameter r = 1.5 μm, Soken Chemical's "MX150"
-Particle <2>: Acrylic particles, average particle diameter r = 3 μm, "Techpolymer SSX-103" manufactured by Sekisui Plastics Co., Ltd.
-Particle <3>: Acrylic particles, average particle diameter r = 10 μm, "Techpolymer SSX-110" manufactured by Sekisui Plastics Co., Ltd.
-Particle <4>: Acrylic particles, average particle diameter r = 20 μm, "Techpolymer SSX-120" manufactured by Sekisui Plastics Co., Ltd.
-Particle <5>: Urethane particles, average particle diameter r = 20 μm, "Art Pearl C300" manufactured by Negami Kogyo
-Binder <1>: Acrylic resin, "Paraclon W197C" manufactured by Negami Kogyo
-Binder <2>: Nylon resin, "Fine Resin FR-104" made by Lead City

(Example 7)
In the preparation of the liquid composition for forming the surface layer, the following particles <6> were used, and a conductive roll was prepared in the same manner as in Example 1 except that a binder was not used. The particles <6> are urethane particles having an NCO group on the surface, and on the surface layer, each particle reacts at a mutual contact portion to form a chemical bond, and the particles are bonded at the mutual contact portion by this chemical bond.
-Particle <6>: Urethane particles having NCO groups on the surface, average particle size: 10 μm, isocyanate group content: 5.0% by mass, dissociation temperature: about 150 ° C.

(Synthesis of particle <6>)
1000 g of Takenate D170-N (isocyanurate) / Mitsui Chemicals (isocyanate group content 20.7% by mass), 120 g of methyl ethyl ketooxime, and 0.1 g of dibutyltin dilaurate were charged in the autoclave, and the inside of the autoclave was sufficiently replaced with nitrogen gas. After that, the mixture was stirred and mixed at 60 ° C. for 12 hours to react. Then, toluene was added to obtain an intermediate (A) (solid content 80%) containing a blocked isocyanate group-containing polyisocyanate prepolymer. Next, 600 g of water was charged into a flask equipped with a stirrer, and 24 g of Metrose 65SH-400 (Shin-Etsu Chemical) was dissolved therein to prepare a dispersion medium. While stirring the dispersion medium at 600 rpm, a mixture of 356 g of the intermediate (A) and 15 g of PolyTHP Polyether (manufactured by BASF) (polytetramethylene glycol, hydroxyl value 113 mgKOH / g) as a polyol was added to prepare a suspension. Then, the suspension was heated to 60 ° C. under continuous stirring, reacted for 8 hours, and then cooled to room temperature to obtain a suspension. This suspension was separated into solid and liquid, washed thoroughly with water, and then dried at 70 ° C. for 20 hours to obtain urethane particles having an NCO group on the surface.

Image evaluation related to chargeability was performed on each of the produced conductive rolls. The evaluation results and the compounding composition of the surface layer forming composition are shown in the table below. In addition, an SEM photograph of the surface of the charged roll of the example was taken to confirm the surface structure. Example 1 is shown in FIG. 3 as a representative example.

(Thickness of surface layer)
The measurement was performed by observing the cross section using a laser microscope (manufactured by KEYENCE, "VK-9510"). Specifically, the distances from the surface of the elastic layer to the vertices of the particles appearing on the surface of the surface layer were measured at five arbitrary positions and expressed by the average.

(Image evaluation)
The produced conductive roll was attached to a cartridge (black) of an actual machine (“CLJ4525dn” manufactured by HP), and image was performed in a 25% concentration halftone under a 15 ° C. × 10% RH environment. Those with no unevenness in the image were rated as good "○", and those with unevenness in the image were rated as "x".

As shown in FIG. 3, the surface layer of the example is composed of an aggregate of a plurality of particles, and each particle is joined at a contact portion with each other and a gap is formed between the particles. It is made porous by the voids of. Then, from Examples 1 to 3 and Comparative Example 1, it can be seen that when the average particle size of the particles is within a predetermined range with respect to the thickness of the surface layer, the discharge amount becomes large and stable charging can be realized even at a low applied voltage. .. Then, from Examples 1 to 6 and Example 7, it can be seen that stable charging can be similarly realized even at a low applied voltage if the particles are bonded at mutual contact portions by chemical bonds even without a binder.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. ..

10 Conductive roll 12 Shaft body 14 Elastic body layer 16 Surface layer

Claims (5)

A shaft body, an elastic body layer formed on the outer periphery of the shaft body, and a surface layer formed on the outer periphery of the elastic body layer are provided.
The surface layer is composed of aggregate of a plurality of particles having an average particle diameter of 20% to 90% relative to the thickness of the surface layer, the particles with each particle are bonded are bound in mutual contact portion by a binder Voids are formed between the particles, and the voids between the particles make the particles porous.
A conductive roll for electrophotographic equipment, which is characterized by being used as a charging roll. The content of the binder, the conductive roller for electrophotographic apparatus according to claim 1, characterized in that in the range of the plurality of particles 100 parts by weight per 0.1 to 10 parts by weight. A shaft body, an elastic body layer formed on the outer periphery of the shaft body, and a surface layer formed on the outer periphery of the elastic body layer are provided.
The surface layer is composed of an aggregate of a plurality of particles having an average particle size of 20 to 90% with respect to the thickness of the surface layer, and each particle is bonded at a mutual contact portion by a chemical bond and between the particles. Voids are formed, and the voids between the particles make the particles porous.
A conductive roll for electrophotographic equipment, which is characterized by being used as a charging roll. The conductive roll for an electrophotographic apparatus according to claim 3 , wherein the conductive roll does not contain a binder. The conductive roll for an electrophotographic apparatus according to any one of claims 1 to 4, wherein the thickness of the surface layer is in the range of 5 to 30 μm.

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