JPH11231614A - Charge imparting member, transfer device using the same and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge imparting member capable simply realizing a semiconductive electric resistance region to be required for various charge imparting members, very small in the variation of electric resistance due to the environment of the use, and further capable of extending the range of impressed bias for obtaining an excellent image by the action for suppressing the generation of excessive current accompanying the boost of an impressed voltage, and to provide a transfer device and an image forming device using the member. SOLUTION: This invention relates to the charge imparting member R1 of a roller form such as electrifying roller, a transfer rollers containing a multiple metallic oxide composed of three or more kinds of metallic oxides, or the charge imparting member R1 of a belt form such as a transfer handler belt or an intermediate transfer belt containing the multiple metallic oxide composed of three or more kinds of metallic oxides and a carbon black having >=1.5% volatile matter. Also, this invention relates to a transfer device and an image forming device using the member R1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, etc., and more particularly to a charging member for applying a charging bias to charge an image carrier surface and an image. A transfer member that is disposed opposite to the carrier and allows the transfer material to pass between the image carrier and a transfer member that applies a transfer bias to apply a charge to the transfer material rear surface, and is disposed to face the image carrier; A transfer / transporting member for carrying a transfer material while electrostatically adsorbing the transfer material to / from the image carrier; a toner image formed on the surface of the image carrier being carried on the surface by primary transfer means; TECHNICAL FIELD The present invention relates to an intermediate transfer member for transferring to a transfer material surface by means, and a transfer device and an image forming apparatus using the same.

[0002]

2. Description of the Related Art In recent years, as a method of applying electric charge in an electrophotographic image forming apparatus, a contact-type electric charge applying method has been widely used instead of the conventional corotron method. For example, when a uniform charge is applied to the surface of the image carrier, the charging member is formed into a roller shape, and is brought into contact with the image carrier. There are advantages such as a small number and a reduction in the size of the charging bias power supply. Also, in the case of applying a charge to the back surface of the transfer material, the transfer member is formed in a roller shape so as to face the image carrier, and the transfer material is passed between the two members, and a transfer bias is applied to the back surface of the transfer material. It is a method of directly applying an electric charge, and again, the amount of ozone generated is small,
In addition, there is an advantage that the transfer bias power supply can be downsized.

Further, the transfer material is transported while being electrostatically attracted,
Also in the transfer conveyance method in which a transfer bias is applied to form a toner image on a transfer material, a roller-shaped suction member is brought into contact with one end of a transfer conveyance member formed in a drum or belt shape, and the transfer material is put between the two. The transfer material is conveyed while being adsorbed to the transfer conveyance member by directly applying a suction bias while passing the transfer material, and the charge is directly applied by a roller-shaped transfer bias means existing on the back surface of the transfer material suction surface of the transfer conveyance member to transfer the transfer material. This is a method of forming a toner image on a material, and similarly has the advantages that the amount of generated ozone is small and the transfer bias power supply can be reduced in size.

In addition, in an intermediate transfer system in which a toner image formed on a surface of an image carrier is carried on the surface by a primary transfer means and the toner image is transferred to a surface of a transfer material by a secondary transfer means, a drum is also used. Alternatively, a method in which a primary transfer roller and a secondary transfer roller are brought into contact with an intermediate transfer member formed on a belt to directly apply an electric charge, similarly producing a small amount of ozone and miniaturizing a transfer bias power supply. This has the advantage that paper adaptability can be expanded. Now, in order to realize each method such as charging, transfer, transfer and transfer, and intermediate transfer using the above-described charge applying members, it is important that each member be contained in a certain electric resistance region.

In the charging roller, an excessive current flows even when a pinhole or a flaw (scratch) is present on the image carrier, so that the surrounding charging failure (so-called pinhole leak) and the charging member itself are not damaged. From the lower limit of the resistance value, there is an upper limit resistance value at which the applied voltage causes a voltage drop due to the internal resistance of the charging member and does not cause spot-like potential unevenness (so-called sand image) on the image. It is empirically known that the specific resistance value is in the range of 1 × 10 ⁵ Ω to about 10 ⁷ Ω in the thickness direction of the charging member. In the transfer member, the difference in transfer current between the image portion and the non-image portion is reduced to prevent the developer from scattering from the image portion on the transfer material (paper, OHP, etc.) to the non-image portion, and to reduce the transfer bias. There is a lower resistance value for suppressing an afterimage phenomenon (a so-called transfer ghost) caused by injection into the carrier. On the other hand, when the resistance value is too high, a high voltage application (5 kv or more) is required, causing a discharge in the gap between the transfer material and the toner, and causing the toner to be charged to the opposite polarity and to return to the image carrier. Since image omission occurs, there is an upper limit resistance value that can prevent them. It is empirically known that the specific resistance value is in the range of 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω in the thickness direction of the transfer member.

[0006] The transfer / conveying member has a lower resistance value that can suppress transfer unevenness of an image on a transfer material and scattering of toner. If the resistance value is too high, a high voltage is applied (5 kv).
Above), causing a discharge in the gap between the transfer member and the toner, causing the toner to be charged to the opposite polarity and returning to the image carrier, causing image omission, or causing the charge to accumulate in the transfer / transport member and causing self-destaticization. Is not possible, so there is an upper resistance value to prevent them. As a specific resistance value, the surface resistivity of the transfer conveyance member is set to 1 × 10 ⁹ Ω / □.
It has been empirically known that it must be kept within about 1 × 10 ¹² Ω / □. In the intermediate transfer member, especially in the primary transfer, there is a lower resistance value that can suppress transfer unevenness of an image on the intermediate transfer member and scattering of toner. If the resistance value is too high, a high voltage is applied (5 kV or more). In addition, a discharge is caused in the gap between the intermediate transfer member and the toner, and the toner is charged to the opposite polarity and returns to the image carrier, thereby causing image omission or accumulation of electric charge in the intermediate transfer member. Since self-static elimination becomes impossible, there is an upper limit resistance value to prevent them. As a specific resistance value, the surface resistivity of the intermediate transfer member is set to 1 × 10 ⁹ Ω / □ to 1
It is empirically known that it must be kept close to × 10 ¹² Ω / □.

As described above, in order to adjust each charge applying member to a certain electric resistance range, for example, in the case of a charging member, Japanese Unexamined Utility Model Publication No. 58-88645, Japanese Patent Application Laid-Open No. 3-9381, and Japanese Patent Application Laid-Open No. 3-10267. No. 5,009,045, a method using a metal oxide as a conductive agent for rubber and resin as described in
JP-A-1-142569, JP-A-4-31197
No. 2, a method using a polar rubber for rubber and resin, a method using an ionic conductive substance as a conductive agent as described in JP-A-2-198470 and JP-A-6-200921, and the like. Has been proposed.

[0008] In the transfer member, a flat-opened 3-7966.
As described in Japanese Patent Application Laid-Open No. Hei 3-21974, a method using a double oxide as a conductive agent for rubber and resin has been proposed. Japanese Patent Application Laid-Open No. 63-31263 discloses a transfer conveying member and an intermediate transfer member.
As disclosed in JP-A-149079, JP-A-7-92825 and JP-A-8-160575, a method using a conductive carbon black, a metal oxide, an ionic conductive substance or the like as a conductive agent for rubber and resin is proposed. Have been.

[0009]

However, these methods of adjusting the electric resistance have the following problems. First, the case of using a conductive carbon black as a conductive agent, Therefore the powder resistance of 10 ⁰ [Omega] cm or less, the change of the electric resistance is likely to be rapidly relative to the addition amount of the particles. Further, it is very difficult to uniformly disperse the conductive carbon black in rubber and resin, and defects such as partial resistance variation and lumps (agglomerated lump) are likely to occur.
For these reasons, it is very difficult to reproduce a stable resistance value using conductive carbon black. Then, in the case of using a metal oxide as a conductive agent, since the powder resistance is 10 ⁰ Ωcm~10 ³ Ωcm, still lacking in reproducibility of the resistance value with respect to the amount added. Also, titanium oxide,
Metal oxides such as tin oxide exhibit conductivity by disposing a layer doped with antimony on the surface of metal oxide particles. Therefore, it is harmful in consideration of abrasion due to rubbing with other members and the case of waste, and it is hard to say that it is a preferable conductive agent.

Further, when a double oxide such as a solid solution of zinc oxide and aluminum oxide, a solid solution of tin oxide and antimony oxide, and a solid solution of indium oxide and tin oxide is used as the conductive agent, the powder resistance is 10 ^1. Ωcm~10 ³ Ωcm some reason, still lacks reproducibility of the resistance value with respect to the amount added.
In addition, there is also a problem that these fillers are difficult to be uniformly dispersed because of large variation in particle diameter. Furthermore, even if two or more of the various fillers described above are used in combination, the problems of the various fillers cannot be fundamentally solved.

In addition to the problems described above, the powder resistance of conductive carbon black, metal oxides, double oxides and the like is 10
^When a filler of ³ Ωcm or less is used as a conductive agent, there is also a problem that the amount of current is apt to increase sharply with an increase in applied voltage. This means that the powder resistivity is 10 ³ Ωc
m or less, the current generated as the applied voltage increases is concentrated on the filler, and the filler itself does not function as a resistor, so that an excessive current is likely to flow.

This phenomenon is common to all the charge applying members, and the following adverse effects are likely to occur. In the charging member, the discharge current increases with an increase in the applied voltage due to the minute gap between the image carrier and the charging member, thereby promoting the wear of the surface of the image carrier and shortening the life of the product. In addition, fine black streaks (so-called abnormal discharge) appear on the image as the applied voltage increases.
Appear easily, and the good image range with respect to the applied voltage becomes narrow. Further, surrounding charges flow into a surface defect (a so-called pinhole) of the image carrier, and a black band due to poor charging appears on the image or the charging member itself is destroyed.

In the transfer member, an excessive current is generated with an increase in the applied voltage, so that a difference in resistance between the image portion and the non-image portion causes
Since the amount of current to the non-image portion having a low resistance increases, toner scattering around the image portion becomes severe, and the current flowing into the image carrier greatly differs between the image portion and the non-image portion. ,
An afterimage phenomenon (a so-called transfer ghost) tends to appear on the image carrier.

In the transfer conveying member, discharge is easily caused in the gap between the transfer material and the toner as the applied voltage increases,
Since the toner is charged to the opposite polarity and returns to the image carrier, image omission occurs, or the inflow current into the image carrier greatly differs between the image portion and the non-image portion, so that an afterimage phenomenon (so-called transfer) occurs on the image carrier. Ghosts) easily appear.

In the intermediate transfer member, a discharge is easily caused in the gap between the intermediate transfer member and the toner with an increase in the applied voltage at the primary transfer portion, and the toner is charged to the opposite polarity and returns to the image carrier to cause an image. Since an omission occurs and the current flowing into the image carrier greatly differs between the image portion and the non-image portion, an afterimage phenomenon (a so-called transfer ghost) is likely to appear on the image carrier. In addition, even when the resistance of the primary transfer member and the secondary transfer member used in the intermediate transfer device is adjusted with a filler having a powder resistance of 10 ³ Ωcm or less, the toner image returns to the image carrier as described above. And afterimage phenomenon (so-called transfer ghost)
Is easy to appear.

On the other hand, when an ionic conductive substance or a polar material is used as the conductive agent, the electric resistance is largely fluctuated due to the use environment, particularly the humidity, and the electric charge required for each of the charge applying members is required. The resistance does not fall within the resistance range, and a problem easily occurs in image formation.

The present invention has been made in view of the above-mentioned problems, and has an object of the following description (O01). (O01) It is possible to easily realize a semiconductive electric resistance region required for various charge imparting members, and there is very little fluctuation in electric resistance due to a use environment. An object of the present invention is to provide a charge applying member capable of expanding a range of an applied bias for obtaining a good image by an action of suppressing current generation, and a transfer device and an image forming apparatus using the same.

[0018]

Means for Solving the Problems (First Invention) In order to solve the above problems, a charge providing member according to a first invention of the present invention comprises:
It is characterized by containing at least a composite metal oxide composed of three or more metal oxides.

(Second Invention) The charge applying member according to the second invention of the present invention is the charge applying member according to the first invention, wherein
The composite metal oxide powder composed of the three or more metal oxides has an electric resistivity of 1 × 10 ⁵ Ωcm or more.

(Third Invention) A charge providing member according to a third invention of the present invention comprises a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more. It is characterized by containing at least.

(Fourth Invention) The charge applying member according to the fourth invention of the present invention is the charge applying member according to any one of the first to third inventions, wherein an electrostatic latent image is formed after being uniformly charged. The electrostatic latent image formed is developed into a toner image, and is a charging member that charges a surface of the image carrier that rotates.

(Fifth invention) A charge applying member according to a fifth invention of the present invention is the image bearing member according to any one of the first to third inventions, wherein the image bearing member rotates and moves and forms a toner image. Formed along the body surface, to form a transfer area through which a transfer material passes between the image carrier surface,
The image forming apparatus is a transfer member that transfers a toner image on the surface of the image carrier to a surface of a transfer material that passes through the transfer area.

(Sixth invention) The charge application member according to the sixth invention of the present invention is the charge application member according to any one of the first to third inventions, wherein the image carrier is configured to rotate and form a toner image. The image forming apparatus is a transfer / transport member that electrostatically attracts and conveys a transfer material on which the toner image on the image carrier is transferred to a toner image transfer area set along the body surface.

(Seventh invention) The charge applying member according to the seventh invention of the present invention is the image bearing member according to any one of the first to third inventions, wherein the image carrying member rotates and moves to form a toner image. In the primary transfer area set along the body surface, the toner image on the image carrier is primarily transferred, and the primary-transferred toner image is secondarily transferred to the transfer material in the secondary transfer area. And an intermediate transfer member.

(Eighth invention) The charge applying member according to the eighth invention of the present invention is the image bearing member according to any one of the first to third inventions, wherein the image carrying member is rotated and forms a toner image. Forming a primary transfer area that is arranged along the body surface and passes through an intermediate transfer member that rotates and moves between the image carrier and the surface of the image carrier; It is a primary transfer member for primary transfer of a toner image on a body surface.

(Ninth invention) A charge applying member according to a ninth invention of the present invention is the image bearing member according to any one of the first to third inventions, wherein the image bearing member rotates and moves to form a toner image. It is a secondary transfer member that secondary-transfers the toner image primarily transferred from the body surface to the surface of the intermediate transfer member by the primary transfer member to the surface of the transfer material.

(Tenth Invention) A process cartridge according to a tenth invention of the present invention comprises: a rotatable image carrier;
A process cartridge comprising at least a charging member for charging the surface of the image carrier, a developing unit for developing a latent image formed on the surface of the image carrier with toner, and a cleaning unit for cleaning the surface of the image carrier. The charging member comprises a composite metal oxide composed of three or more metal oxides, or a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more. It is characterized by containing.

(Eleventh invention) An image forming apparatus according to the eleventh invention of the present invention has a charging member for charging the surface of the rotating image carrier and forms a toner image on the charged image carrier surface. Forming a transfer area between the toner image forming means and the image carrier, wherein the transfer area allows the transfer material to pass therethrough, and the image is formed on the surface of the transfer material passing through the transfer area. In an image forming apparatus including at least a transfer member for transferring a toner image on a carrier surface, a composite metal oxide in which one or both of the charging member and the transfer member are formed of three or more metal oxides; Alternatively, it is characterized by containing at least a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more.

(Twelfth Invention) A transfer device according to a twelfth invention of the present invention is characterized in that the image carrier is rotated in a toner image transfer area set along the surface of the image carrier on which a toner image is formed. A transfer and conveyance member for electrostatically adsorbing and transferring a transfer material onto which a toner image on a body surface is transferred, an electrostatic attraction member for electrostatically adsorbing the transfer material to the transfer and conveyance member, and a transfer material attraction of the transfer and conveyance member And at least one of a transfer conveying member, an electrostatic attraction member, and a transfer member, each of which includes at least three types of metal oxides. Or at least a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more.

(Thirteenth Invention) In the image forming apparatus according to the thirteenth invention, the electrostatic latent image is formed after being uniformly charged, and the electrostatic latent image is developed into a toner image and rotated. A charging member for charging the moving surface of the image carrier, and a transfer material on which the toner image on the surface of the image carrier is transferred by electrostatic attraction to a toner image transfer area set along the surface of the image carrier; A transfer conveyance member, an electrostatic attraction member for electrostatically adsorbing a transfer material to the transfer conveyance member, and a transfer member disposed on a back surface of a transfer material attraction surface of the transfer conveyance member and transferring a toner image to the transfer material. Wherein at least one of the charging member, the transfer conveyance member, the electrostatic attraction member, and the transfer member is a composite metal oxide composed of three or more metal oxides, or 3 More than one kind of metal oxide Characterized in that it contains at least the configured composite metal oxide as a volatile content of 1.5% or more of carbon black Ri.

(A fourteenth invention) A transfer device according to a fourteenth invention of the present invention is arranged along the surface of an image carrier on which a toner image is formed while rotating and moving, and is provided between the transfer device and the surface of the image carrier. A primary transfer region for forming a primary transfer region through which the rotating intermediate transfer member passes, and a primary transfer member for primarily transferring a toner image on the surface of the image carrier to the surface of the intermediate transfer member passing through the primary transfer region; An inner secondary transfer member that supports the back surface of the rotating intermediate transfer member, an outer secondary transfer member that is disposed opposite the inner secondary transfer member with the intermediate transfer member interposed therebetween, and the inner secondary transfer member. Inside contact 2
A secondary transfer member having an electrode member for supplying a secondary transfer voltage to a secondary transfer member and secondary-transferring a toner image primary-transferred onto the intermediate transfer member surface by the primary transfer member to a transfer material surface; In the transfer apparatus provided at least, any or all of the intermediate transfer member, the primary transfer member, the inner secondary transfer member, the outer secondary transfer member, and the electrode member are three or more types of metal oxides. Or at least a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more.

(Fifteenth Invention) In the image forming apparatus according to the fifteenth invention, the electrostatic latent image is formed after being uniformly charged, and the electrostatic latent image is developed into a toner image and rotated. A charging member that charges the moving image carrier surface, and a primary transfer area that is arranged along the image carrier surface and passes an intermediate transfer member that rotates and moves between the image carrier surface and the primary transfer region; A primary transfer member that primarily transfers the toner image on the surface of the image carrier to the surface of the intermediate transfer member that passes through the primary transfer area; and an inner secondary transfer member that supports the back surface of the rotating intermediate transfer member. An electrode for supplying a secondary transfer voltage to the inner secondary transfer member by contacting the outer secondary transfer member and the inner secondary transfer member disposed opposite to the inner secondary transfer member with the intermediate transfer member interposed therebetween. A member for the primary transfer member. And a secondary transfer member for secondary-transferring the toner image primary-transferred onto the surface of the intermediate transfer member to the surface of the transfer material, wherein the charging member, the intermediate transfer member, the primary transfer member, Any or all of the inner secondary transfer member, the outer secondary transfer member, or the electrode member is composed of a composite metal oxide composed of three or more metal oxides, or composed of three or more metal oxides. It is characterized by containing at least a composite metal oxide and carbon black having a volatile content of 1.5% or more.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The charge applying member according to the present invention has a layer containing a composite metal oxide composed of at least three types of metal oxides. The composite metal oxide used in the present invention is copper, iron, manganese, nickel, zinc, cobalt, barium, aluminum, tin, lithium, magnesium, silicon, oxides containing different metal elements such as phosphorus, hydroxide, It is a solid solution of a metal oxide obtained by firing at least three types selected from carbonates, metal compounds, and the like at a high temperature (800 to 1500 ° C.), and has the following characteristics. (1) Since it is fired at a high temperature, a stable electric resistance with few impurities can be obtained. Since it is easily crushed, the particle size is extremely high and the dispersibility is excellent. (2) Excellent heat resistance, solvent resistance, and weather resistance. As in the case of general metal oxides, antimony is not doped on the outer periphery of the metal oxide to exhibit conductivity, so that the safety is high.

The above characteristics are very advantageous for the charge applying member used in the electrophotographic apparatus. That is, (1) When a filler having a small amount of impurities and having a stable electric resistance is used, the change in electric resistance with respect to the filler addition amount is very small. Therefore, it is easy to adjust the resistance value. (2) Since the particle size is uniform, it can be easily and uniformly dispersed in rubber and resin or a material dissolved in a solvent. (3) It has excellent heat resistance, solvent resistance and weather resistance, so it does not disperse in materials having a high melting point or deteriorates or deteriorates even when used for long-time vulcanization at high temperatures. Even if there is no problem, it is hardly affected by various physical properties such as electric resistance even when the temperature and humidity change. (4) Since antimony is not used, the safety is extremely high even when rubbing with another member or discarding is considered.

In addition, oxides containing different metal elements,
A composite metal oxide obtained by calcining at least three types selected from hydroxides, carbonates, metal compounds, and the like at a high temperature (800 to 1500 ° C.) forms a solid solution of different atoms having different valences to form a solid solution. By substituting the lattice positions or forming unsaturated ions near the lattice positions, a donor level is formed to facilitate the excitation of electrons to the conductor, and the electric resistivity of the powder becomes 10 ⁵ Ωcm or more, especially 10 ⁵ Ωcm or more. ⁷ Ωcm to 10 ¹² Ωc
m semiconductor regions.

Therefore, when used as a semiconductive charge imparting member dispersed in a matrix component, the filler functions as a resistor with respect to an increase in applied voltage. ) Can be suppressed. Due to this action, a discharge current in a minute gap formed between the image carrier and the charging member can be suppressed to a small amount with respect to an increase in the applied voltage, so that the surface of the image carrier is worn away. This has the effect of extending the life of the product. In addition, fine black streaks (so-called abnormal discharge) do not appear on the image as the applied voltage increases, and the good image range with respect to the applied voltage can be significantly expanded. Further, the surrounding charges flow into surface defects (so-called pinholes) of the image carrier, so that a black band due to poor charging does not appear on the image, and the destruction of the charging member itself can be prevented.

Similarly, when used as a transfer member, an excessive current which is likely to occur with an increase in the applied voltage can be suppressed, so that the resistance difference between the image portion and the non-image portion causes the non-image portion having a low resistance to be transferred to the non-image portion. An increase in the amount of current can prevent the toner from scattering around the image area, and the current flowing into the image carrier can also be reduced to a small extent between the image area and the non-image area. (So-called transfer ghost) hardly appears. That is, the good image range with respect to the applied voltage can be significantly expanded.

When used as a transfer conveyance member,
Since the discharge that easily occurs in the gap between the transfer material and the toner due to the increase in the applied voltage can be suppressed, the image is prevented from being lost due to the toner being charged to the opposite polarity and returning to the image carrier, and the toner flows into the image carrier. Since the difference in current between the image portion and the non-image portion is also reduced, the afterimage phenomenon (so-called transfer ghost) hardly appears on the image carrier. That is, the good image range with respect to the applied voltage can be expanded in a chopstick manner.

Further, when used as an intermediate transfer member,
Prevents a discharge that easily occurs in the gap between the intermediate transfer member and the toner due to an increase in the applied voltage at the primary transfer portion, and prevents an image omission caused by the toner being charged to the opposite polarity and returning to the image bearing member. In addition, since the difference between the current flowing into the image carrier and the image portion and the non-image portion can be reduced, the afterimage phenomenon (so-called transfer ghost) hardly appears on the image carrier. That is, the good image range with respect to the applied voltage can be significantly expanded. By using the composite metal oxide as the filler of the charge applying member according to the present invention, various effects are obtained, and the performance of the transfer device and the image forming apparatus obtained by combining various charge applying members is remarkably improved. It is.

The electrical resistance of the composite metal oxide used in the present invention is J under a standard environment of a temperature of 22 ° C. and a humidity of 55%.
The electrical resistivity of the powder was determined from the following equation (1) according to IS-K1469. ρ = (S / h) × (V / I) (1) where: ρ: electric resistivity of powder (Ωcm) S: of sample Cross-sectional area (cm ² ) h: filling height of sample (cm) V: potential difference (V) I: current (A), and each measured value is a state in which a pressure of 50 kgf / cm ² is applied. .

When adjusting the electric resistance in a region lower than the electric resistivity of the above-mentioned composite metal oxide powder, or when it is desired to keep the hardness of the charge applying member low, carbon can be used in combination. . However, it is desirable that the carbon used in combination has a volatile content of 1.5% or more, particularly 5% or more. The volatile matter referred to here is an oxide film formed on the surface of the carbon particles. If the volatile content is less than 1.5%, the conductivity remains high, so that the conductivity of the carbon particles becomes dominant, and the effect of the composite metal oxide is hardly exhibited. On the other hand, the upper limit of the volatile content is not particularly defined or is preferably 30%.
If the volatile content exceeds 30%, the conductivity is too low, a large amount of carbon is required, and the hardness of the charge imparting member may become too high, or the surface may have irregularities.

As described above, when carbon having a certain range of volatile components is used together, a composite metal oxide enters between carbon particles and maintains the function as a resistor against an increase in applied voltage. Therefore, there is no change in the effect of suppressing an excessive increase in the amount of current caused by an increase in the applied voltage. In addition, as long as the effect of the composite metal oxide is not impaired even when metal powders other than carbon and metal oxides not doped with harmful substances are used in combination,
There are no restrictions.

As the matrix component forming the layer containing the composite metal oxide, natural rubber, synthetic natural rubber, styrene rubber, phthalene rubber, chloroprene rubber, butyl rubber, nitrile rubber, nitrile butadiene rubber, ethylene propylene rubber, chlorosulfone Rubber, such as chlorinated polyethylene, acrylic rubber, urethane rubber, silicone rubber, fluorine rubber, polysulfide rubber, epichlorohydrin rubber, or an elastomer and a mixture or copolymer thereof, polyethylene, polypropylene, polystyrene, polyisobutylene, polyester, polyurethane , Polyamide, polyimide, polyamideimide, alcohol-soluble nylon, polycarbonate, polyarylate, phenol, polyoxymethylene, polyetheretherketone, police Azen, polysulfone,
Thermoplastic resins and thermosetting resins such as polyether sulfide, polyphenylene oxide, polyphenylene ether, polyparabanic acid, polyallylphenol, polybenzimidazole, polyurea, fluorine, polyurea, ionomer, silicone, or mixtures and co-polymers thereof Examples include polymers.

The method for producing the charge applying member according to the present invention is a method of dissolving the rubber, elastomer, resin or the like in a solvent and dispersing the composite metal oxide or the composite metal oxide and carbon to form a coating, or the rubber, elastomer, resin or the like. Alternatively, a composite metal oxide or a composite metal oxide and carbon may be kneaded into a molded body or a foamed body, or formed into a tubular shape and fitted to a support member.

However, when a composite metal oxide or a composite metal oxide and carbon are dispersed in a solvent by dissolving a rubber, an elastomer, a resin or the like in a solvent and used as a paint, the charge imparting member according to the present invention contains the composite metal oxide. Since the composite metal oxide has an effect of suppressing excessive current even at a high applied voltage due to the powder resistance of the composite metal oxide itself and at the same time reducing the amount of discharge current, the charge applying member has It is most effective to use it as an outer layer (surface layer). In this case, as a matrix component forming a layer containing the composite metal oxide, it is desirable to use a fluorine-based material which is less likely to adhere toner and paper powder, and has excellent environmental stability and non-staining properties.

The shape of the charge applying member according to the present invention may be any of a roller, a belt, a blade, and the like, and the configuration thereof is not limited at all. FIG. 1 is a view showing a configuration example in which the present invention is applied to a roller-shaped charge applying member, and FIG. 1A is a roller having a configuration in which only one base layer containing a composite metal oxide is formed on the surface of a cored bar. 1B is a roller-shaped charge applying member in which the surface of the base layer of FIG. 1A is coated with a surface layer, and FIG. 1C is a structure in which the surface of the base layer of FIG. 1A is sequentially coated with a protective layer and a surface layer. It is a figure which shows the charge provision member of FIG. FIG. 2 is a diagram showing a configuration example in which the present invention is applied to a belt-shaped charge applying member. FIG. 2A is a belt-shaped charge applying member having only a base layer containing a composite metal oxide, and FIG. FIG. 2A
2C is a diagram showing a belt-shaped charge applying member having a structure in which the surface of the base layer is covered with a surface layer, and FIG. 2C is a diagram showing a charge applying member having a structure in which a surface layer is formed on the surface of the base layer of FIG. 2A via an adhesive layer.

The roller-shaped charge applying member R shown in FIG. 1A
1 is composed of a core metal R1a and a base layer R1b containing a composite metal oxide composed of three or more metal oxides covering the surface of the core metal R1a. The roller-shaped charge imparting member R1 shown in FIG. 1B includes a base metal R1a and a base layer R1b containing a composite metal oxide composed of three or more metal oxides covering the surface of the base metal R1a, and a surface of the base layer R1b. It is composed of a surface layer R1c to be covered. The roller-shaped charge applying member R1 shown in FIG. 1C includes a base layer R1b containing a composite metal oxide composed of a core metal R1a and three or more metal oxides covering the surface of the core metal R1a, and a surface of the base layer R1b. It is composed of a protective layer R1d and a surface layer R1c sequentially formed on the outside. The material of the surface layer R1c formed outside the base layer R1b of the roller-shaped charge applying member R1 is, for example, a fluorine-based material, and the protective layer R1d is, for example, an alcohol-soluble material having a solubility coefficient (SP value) different from that of the base layer R1b. Materials such as nylon can be used.

The belt-shaped charge applying member R shown in FIG. 2A
Reference numeral 2 denotes a single-layer base layer R2a containing a composite metal oxide composed of three or more metal oxides. The belt-shaped charge applying member R2 shown in FIG.
It comprises a base layer R2a containing a composite metal oxide composed of at least one kind of metal oxide and a surface layer R2b covering the surface of the base layer R2a. The belt-shaped charge applying member R2 shown in FIG. 2C includes a base layer R2a containing a composite metal oxide composed of three or more metal oxides and the base layer R2.
2a, a surface layer R formed outside the surface via an adhesive layer R2c.
2b. The surface layer R2 formed outside the base layer R2a of the belt-shaped charge applying member R2.
b, For example, the following materials can be used as the adhesive layer R2c. (Example of material of surface layer R2b) Fluorine resin excellent in mold release property,
Polyimide, polyamide imide, polyethylene, polypropylene, etc. (Example of material of adhesive layer R2c) Adhesive material such as epoxy, silicon, urethane, polyester, and nylon in which conductive carbon and metal powder are dispersed.

When the charge applying member according to the present invention is used in the form of a roller, it may be a single layer or a plurality of layers as shown in FIG. 1, and when it is used as a belt, it may be a single layer as shown in FIG. Multiple layers may be used. In addition, when a plurality of layers are formed in any of the shapes, a primer or an adhesive may be used in order to improve the secretivity between the layers. Further, the thickness of the layer containing the composite metal oxide may be arbitrarily set as long as it does not affect the hardness required for the intended charge providing member.

[0050]

The present invention will be described below in more detail with reference to examples. (Example 1) Lumiflon LF-6 which is a fluorine-modified resin
00C (Asahi Glass Co., Ltd.) and Lumiflon LF-601C
(Asahi Glass Co., Ltd.) was mixed at a ratio of 1: 1 and then dissolved in a mixed solvent of the same amount of toluene and xylene at a solid content of 30% by weight. The change in electric resistance with respect to the amount added (parts by weight) was observed. At this time, the filler was dispersed by a sand mill for 8 hours. Thereafter, 25 parts by weight of a curing agent (Nippon Polyurethane Co., Ltd. Coronate HL) was added to the fluorine-modified resin, and both were sufficiently stirred. Spray coating with 2Kg / cm ² air pressure
The volume resistivity of the thin film having a thickness of 100 μm obtained by curing at 60 ° C. for 20 minutes was measured using a Hirester IP resistance meter and an HR probe (both manufactured by Mitsubishi Yuka) at an applied voltage of 500 V
It was determined from the measured value at an application time of 30 seconds using the following equation (2). ρ _v = Log ₁₀ (S × Rv / t) (2) where ρ _v : volume resistivity (LogΩcm) S: cross-sectional area of HR probe (cm ² ) Rv : Actual measured volume resistance (Ω) t: Thickness (cm)

FIG. 3 is a graph showing the relationship between the added amount of various fillers and the volume resistivity. The conditions for obtaining the graphs A to E in FIG. 3 are as follows. A: It is composed of copper oxide (CuO), iron oxide (Fe2O3), and manganese oxide (Mn2O3), and the electrical resistivity of the powder is 1
× 10 ⁷ Ωcm composite metal oxide (CuO-Fe2O3)
-Added Mn2O3). B: Iron oxide (Fe2O3), zinc oxide (ZnO), titanium oxide (TiO2), and the electric resistivity of the powder is 1 × 1
0 ⁹ complex metal oxide is Ωcm (Fe2O3-ZnO-Ti
O2) added amount changed. C: The addition amount of the coloring carbon black having a volatile content of 0.2% was changed. D: The amount of coloring carbon black having a volatile content of 5.0% was changed. E: The addition amount of the coloring carbon black having a volatile content of 35.0% was changed. FIG. 3 shows that CuO—Fe 2 O 3 —Mn 2 O 3 and Fe 2 O 3 —Z
It can be seen that the composite metal oxide of nO-TiO2 can adjust the electric resistance within a certain range (in particular, the electric resistance range of the transfer member) even when used alone.

FIG. 4 is a graph showing the relationship between the added amount of various fillers and the volume resistivity. The conditions for obtaining the graphs F to J in FIG. 4 are as follows. F: The composite metal oxide A was 20 parts by weight, and the amount of the coloring carbon black having a volatile content of 0.2% was changed. G: The amount of the composite metal oxide A was 20 parts by weight, and the amount of the coloring carbon black having a volatile content of 1.9% was changed. H: The composite metal oxide A was 20 parts by weight, and the amount of coloring carbon black having a volatile content of 5.0% was changed. I: The composite metal oxide A was 20 parts by weight, and the amount of the coloring carbon black having a volatile content of 8.5% was changed. J: 20 parts by weight of the composite metal oxide A, volatile matter 1
The amount of carbon black for coloring, which is 0.0%, was changed. From FIG. 4, it is found that stable electric resistance can be realized even in the electric resistance region of the charging member by using the composite metal oxide A and carbon having a volatile content of 1.5 to 9.0% in combination. Although not shown in the figure, the composite metal oxide B can also exhibit the same resistance as the metal oxide A by using various fillers in combination.

(Example 2) A diameter of 8 mm and a length of 350 mm
Conductive carbon (Kethje) on silicon rubber
nBlack EC) was blended in an amount of 15 parts by weight to form an elastic layer having a thickness of 3 mm and a length of 320 mm. Separately, Lumiflon LF-600C (Asahi Glass Co., Ltd.) and Lumiflon LF-601C (Asahi Glass Co., Ltd.), which are fluorine-modified resins, are mixed at a ratio of 1: 1 and then mixed with the same amount of toluene and xylene. A solid content of 30% by weight is dissolved in a solvent, and copper oxide (CuO) and iron oxide (Fe2
O3), 20 parts by weight of a composite metal oxide (CuO-Fe2O3-Mn2O3) composed of manganese oxide (Mn2O3) and having an electric resistivity of 1 * 10 < ⁷ > [Omega] cm, and carbon black having a volatile content of 50%. 7 parts by weight of Raven 3500 (Columbian Carbon Co., Ltd.) was blended and dispersed using a sand mill for 8 hours.

Next, a curing agent (Nippon Polyurethane Co., Ltd.)
(Coronate HL) was added to the fluorine-modified resin in an amount of 25 parts by weight, and both were sufficiently stirred to produce a semiconductive coating. The obtained paint was spray-coated on the outer periphery of the elastic layer prepared above at an air pressure of 2 kg / cm ² to a thickness of 50 μm.
Thus, a charging roller having a surface layer of m was prepared. The resistance in the thickness direction between the core metal and the roller surface of the obtained charging roller was measured by applying a DC voltage of 500 V for 10 seconds under each environment. The results were as follows and were extremely stable. Standard environment (22 ° C., 55%): 5 × 10 ⁵ Ω, high temperature and high humidity environment (28 ° C., 85%): 4 × 10 ⁵ Ω, low temperature and low humidity environment (10 ° C., 15%): 5 × 10 ⁵ Ω The other physical properties are as follows. Hardness: 55 ° (Asker-C hardness meter, 1 kg load) Surface roughness: Rz = 0.8 μm (10-point average roughness) Then, the obtained charging roller was used for an image forming apparatus using a process cartridge shown in FIG. At the image carrier surface charging position (primary charging position), the process speed was 68
mm / sec, DC voltage -500V under each environment
The change in the amount of current with respect to the increase in the AC voltage superimposed and applied at a frequency of 485 Hz was measured.

FIG. 5 is a schematic illustration of an image forming apparatus using a process cartridge. In FIG. 5, the image recording apparatus U has a process cartridge K. The process cartridge K includes an image carrier 1, a charging roller 2 for uniformly charging the surface of the image carrier 1 at a charging position Q1, A latent image writing device ROS for writing an electrostatic latent image on the surface of the charged image carrier 1 at a latent image writing position Q2; and a developing roller 3a for developing the electrostatic latent image into a toner image in a developing region Q3. A developing device 3, a cleaner 4 for cleaning the surface of the image carrier 1 with a cleaning blade 4a after the toner image is transferred to the transfer material S in the transfer area Q4, and a static eliminator for removing the surface of the cleaned image carrier 1 Five. The recording paper S stored in the paper feed tray 7 is picked up by a pickup roller 8, separated by a separating roller 9 one by one, and then conveyed to a transfer area Q3. The toner image on the body 1 is transferred. The recording paper S to which the toner image has been transferred is fixed with the toner image when passing through the fixing device 11, and is discharged from the discharge roller 12 to the discharge tray 13.

The charging roller 2 of the image forming apparatus U provided with the process cartridge K shown in FIG. 5 is the same as the charging roller manufactured in the second embodiment, and the process speed is set to 68 mm / sec. DC voltage -5 below
The change in the amount of current with respect to the increase in the AC voltage superimposed and applied to 00v at a frequency of 485 Hz was measured. FIG. 6 shows that the charging roller manufactured in Example 2 was processed at a process speed of 68 mm.
/ Sec image carrier at each environment, DC voltage -500V
FIG. 7 is a diagram showing a change in the amount of current with respect to an increase in the AC voltage superimposed and applied at a frequency of 485 Hz. The measurement results are as shown in FIG. 6, and the amount of current did not increase sharply even with an increase in the AC voltage.

At the same time, when the change in the halftone image with respect to the increase in the AC voltage was observed, the sand image disappeared at an AC voltage of 1.1 kvpp under a high-temperature and high-humidity environment. No black streaks (so-called abnormal discharge) were observed. Also, replace the photosensitive drum with 10 pinholes reaching the metal cylinder at equal intervals of 10 mm in the longitudinal direction and 5 mm in the circumferential direction.
Although 0 kvpp was applied, no excessive current flow (so-called pinhole leak) occurred. Similarly, in a low-temperature and low-humidity environment, the sand image disappeared at 1.2 kvpp, and fine black streaks (so-called abnormal discharge) were not observed even after applying an AC voltage of 3.0 kvpp.

Example 3 100 parts by weight of EPDM were composed of copper oxide (CuO), iron oxide (Fe2O3), and manganese oxide (Mn2O3), and the electrical resistivity of the powder was 2 ×
A composite metal oxide (CuO-Fe2O3-Mn) having a resistivity of 10 ⁹ Ωcm
2O3), 40 parts by weight of a process oil, zinc white, and a dispersant auxiliary were kneaded, and a predetermined amount of sulfur, a vulcanization accelerator, a foaming agent, and a foaming auxiliary were blended. The obtained semiconductive rubber was molded into a chicove having an inner diameter of 9 mm and an outer diameter of 15 mm using an extruder, cut into a predetermined length, and then heated to 180 ° C. using an electric furnace.
For 30 minutes to effect vulcanization and foaming. 3
The core was cut into 20 mm, and a core bar having a diameter of 10 mm and a length of 350 mm was press-fitted, and a semiconductive foam roller finished to have an outer diameter of 28 mm by polishing was obtained.

The electrical resistance of the obtained semiconductive foamed roller between the metal core and the roller surface in all directions was measured by applying a DC voltage of 500 V for 10 seconds under each environment. The results were as follows and were extremely stable. Standard environment (22 ° C., 55%): 3 × 10 ⁹ Ω, high temperature and high humidity environment (28 ° C., 85%): 1 × 10 ⁹ Ω, low temperature and low humidity environment (10 ° C., 15%): 6 × 10 ⁹ Ω The hardness was 45 ° (Asker-C hardness meter, 1 kg load).

Next, the obtained semiconductive foamed roller is shown in FIG.
At the position of the transfer roller 10 of the image forming apparatus using the process cartridge shown in FIG.
At 8 mm / sec, a change in the amount of current with respect to an increase in the DC voltage was measured while a transfer material (plain paper) was passed between the transfer member and the image carrier. FIG. 7 shows the current with respect to an increase in the DC voltage when a DC voltage was applied to the transfer roller manufactured in Example 3 while passing a transfer material (plain paper) between the image carrier and a process speed of 68 mm / sec. It is a measure of the change in volume. The measurement results are as shown in FIG. 7, and the amount of current did not suddenly increase even with an increase in the DC voltage.

At the same time, when the change of the halftone image with respect to the increase in the DC voltage was observed, a sufficient image density was obtained at a DC voltage of 0.8 kv in a high-temperature and high-humidity environment, and thereafter, even when a DC voltage of 5.0 kv was applied. Image omission and scattering of the developer hardly occurred. Further, after an image was formed at a DC voltage of 5.0 kv using a postcard made of a transfer material as an official postcard, the image was confirmed on plain paper, but no afterimage phenomenon (a so-called ghost) was observed. Similarly, in a low-temperature and low-humidity environment, a sufficient image density was obtained with a DC voltage of 1.6 kv. Thereafter, even when a DC voltage of 5.0 kv was applied, image omission and scattering of the developer hardly occurred.
Further, after an image was formed at a DC voltage of 5.0 kv using a postcard made of a transfer material as an official postcard, the image was confirmed on plain paper, but no afterimage phenomenon (a so-called ghost) was observed.

Example 4 NBR1OO parts by weight
It is composed of copper oxide (CuO), iron oxide (Fe2O3), and manganese oxide (Mn2O3), and has an electric resistivity of 2 × 1.
0 ⁹ complex metal oxide is Ωcm (CuO-Fe2O3-Mn2
O3), 40 parts by weight, process oil, zinc white, and a dispersant auxiliary were kneaded, and a predetermined amount of sulfur and a vulcanization accelerator were added. The resulting semiconductive rubber was molded into a tube using an extruder, and then heated and vulcanized at 180 ° C. for 30 minutes to produce a belt base material having an inner diameter of 150 mm and an outer diameter of 160 mm.
Separately, Lumiflon LF-6 which is a fluorine-modified resin
00C (Asahi Glass Co., Ltd.) and Lumiflon LF-601C
(Asahi Glass Co., Ltd.) was mixed at a ratio of 1: 1 and then dissolved in a mixed solvent of the same amount of toluene and xylene at a solid content of 30% by weight, and copper oxide (CuO), iron oxide ( 18 parts by weight of a composite metal oxide (CuO-Fe2O3-Mn2O3) composed of Fe2O3) and manganese oxide (Mn2O3) and having an electric resistivity of 1 * 10 < ⁷ > [Omega] cm was mixed and dispersed for 8 hours using a sand mill. .

Next, a curing agent (Nippon Polyurethane Co., Ltd.)
(Coronate HL) was added to the fluorine-modified resin in an amount of 25 parts by weight, and both were sufficiently stirred to produce a semiconductive coating. The obtained coating material is spray-coated on the outer periphery of the belt base material prepared above at an air pressure of 2 kg / cm ² to have a thickness of 5 kg.
A belt with a surface layer of 0 μm was obtained. The surface resistivity and volume resistivity of the obtained belt were measured by applying a DC voltage of 500 V for 10 seconds under each environment. The results were as follows and were extremely stable. Standard environment (22 ° C., 55%): 4 × 10 ¹¹ Ω / □ and 9 × 10 ⁹ Ωcm, high temperature and high humidity environment (28 ° C., 85%): 2 × 10 ¹¹ Ω / □ and 8 × 10 ⁹ Ωcm, Low temperature and low humidity environment (10 ° C., 15%): 5 × 10 ¹¹ Ω / □ and 9 × 10 ⁹ Ωcm

The belt obtained in Example 4 was used as the transfer belt B of the image forming apparatus having the transfer belt B shown in FIG. FIG. 8 is a schematic explanatory view of an image forming apparatus having a transfer conveyance belt. In FIG. 8, the transfer conveyance belt B has a constant process speed of 70 m by a plurality of belt support rollers 21 to 24 including a drive roller 21.
It rotates in the direction of arrow A at a speed of m / min. The attracting roller 25 for attracting the recording paper S to the transfer / conveying belt B has a power of +50.
A voltage of 0 V is applied, and the recording paper S entering from the direction of arrow B is charged. K (black), Y (yellow), M (magenta), C
(Cyan) color image carriers 26k to 26c are arranged,
Around the image carriers 26k to 26c, charging rollers 27k to 27c are arranged upstream of the latent image writing positions Q2k to Q2c along the moving direction of the image carriers, respectively. The developing devices 28k to 28c, the transfer rollers Tk to Tc, and the cleaners 29k to 29c are sequentially arranged on the downstream side of .about.Q2c. The transfer rollers Tk to Tc are the rollers manufactured in the third embodiment, and the image carriers 26k to
26c.

In the image forming apparatus shown in FIG. 8, images were observed while changing the transfer bias applied to the transfer rollers Tk to Tc. As a result, in a high-temperature and high-humidity environment, a sufficient image density was obtained at a DC voltage of 0.8 kv. Thereafter, even when a DC voltage of 5.0 kv was applied, image omission and scattering of the developer hardly occurred. Further, after an image was formed at a DC voltage of 5.0 kv using a postcard made of a transfer material as an official postcard, the image was confirmed on plain paper, but no afterimage phenomenon (a so-called ghost) was observed.
Similarly, in a low-temperature and low-humidity environment, a sufficient image density was obtained with a DC voltage of 1.6 kv, and even when a DC voltage of 5.0 kv was applied, image omission and scattering of the developer hardly occurred.
Further, after an image was formed at a DC voltage of 5.0 kv using a postcard made of a transfer material as an official postcard, the image was confirmed on plain paper, but no afterimage phenomenon (a so-called ghost) was observed.

Example 5 A polyimide varnish for a heat-resistant film (U Varnish-S, Ube Industries, Ltd.) was replaced with copper oxide (Cu).
O), iron oxide (Fe2 O3), composite metal oxide electrical resistivity of the formed powder is 1 × 10 ⁷ Ωcm by manganese oxide (Mn2O3) a (CuO-Fe2O3-Mn2O3) 1
0 parts by weight and 20% volatile carbon Color Bla
8 parts by weight of ck FW200 (manufactured by Degussa Co., Ltd.) were blended and sufficiently mixed with a mixer. This stock solution was uniformly cast at 30 ° C. in a cylindrical mold and centrifugally molded while heating to 130 ° C. The mold was released in a semi-cured state, and then the removed belt was covered with an iron core and heated at 450 ° C. for 30 minutes to obtain a seamless belt having a thickness of 80 μm.

The surface resistivity and the volume resistivity of the obtained belt were measured by applying a DC voltage of 500 V for 10 seconds under each environment. The results were as follows and were extremely stable. Standard environment (22 ° C., 55%): 6 × 10 ¹¹ Ω / □ and 5 × 10 ⁹ Ωcm, high temperature and high humidity environment (28 ° C., 85%): 6 × 10 ¹¹ Ω / □ and 4 × 10 ⁹ Ωcm, Low temperature and low humidity environment (10 ° C., 15%): 7 × 10 ¹¹ Ω / □ and 5 × 10 ⁹ Ωcm. Other characteristics are as follows. Tensile modulus: 50,000 kg / cm ² (JISK-71
27, tensile speed 100 mm / min) Surface roughness: Rz = 0.8 μm (10-point average roughness)

The obtained belt was mounted as an intermediate transfer belt B of the image forming apparatus shown in FIG. FIG. 9 is a schematic explanatory view of an image forming apparatus provided with the intermediate transfer belt B. In FIG. 9, the rotating image carrier 31 rotates in the direction of arrow A, and the surface thereof is uniformly charged by the charging roller 32. The charged image carrier 31 is sequentially moved to K (black), Y (yellow), and M at a latent image writing position Q2 by a laser beam L emitted from a laser writing device (not shown).
(Magenta) and C (cyan) electrostatic latent images are written. The electrostatic latent image sequentially moves to the development area Q3. The developing device 33 that develops the electrostatic latent image in the developing area Q3
This is a rotary type developing device, and it is used to transfer electrostatic latent images to K, Y,
Developing devices 33k to 33c for developing toner images of each color of M and C
The developing units 33k to 33c sequentially rotate and move to the developing area Q3, and develop the electrostatic latent images of the respective colors sequentially moving to the developing area Q3 into toner images of the respective colors.

The rotating image carrier 31 is transferred by the cleaner 34 after the toner images sequentially formed on the surface thereof are successively transferred onto the intermediate transfer belt B by the primary transfer roll T1 in the primary transfer area Q4. Cleaned,
Next, after the charge is removed by the charge remover 35, the charging roller 3
2 to be recharged. The intermediate transfer belt B is rotatably supported by a plurality of belt support rolls 36 to 40 including a driving roll 36, driven rolls 37 to 39, and an inner secondary transfer roll 40. In the region Q4, the toner images of the respective colors K, Y, M, and C are sequentially primary-transferred. The inner secondary transfer roll 4
0 and an outer secondary transfer roll 41 disposed opposite to the inner secondary transfer roll 40 with the intermediate transfer belt B interposed therebetween, to constitute a secondary transfer device T2. A secondary transfer area Q5 is formed in a contact area of the secondary transfer roll 41. An undulating cleaning blade 42 such as polyurethane or silicon is constantly in contact with the outer secondary transfer roll 41, and foreign matters such as toner particles and paper powder attached thereto are removed.

When the recording paper (transfer material) S taken out of the paper feed tray 43 passes through the secondary transfer area Q5, the four color toner images on the intermediate transfer belt B are collectively collected by the secondary transfer device T2. Is secondarily transferred. The intermediate transfer belt B that has passed through the secondary transfer area Q5 is cleaned by the belt cleaner 44. The recording paper S on which the toner image is secondarily transferred is
After passing through the fixing device, the toner image is fixed and then discharged to a discharge tray (not shown).

In the image forming apparatus using the intermediate transfer belt shown in FIG. 9, the roller manufactured in the third embodiment is used as the primary transfer roller T1 and the outer secondary transfer roller 41 is manufactured in the second embodiment. The elastic layer is 10 mm in diameter and 350 in length.
mm on the outer circumference of the cored bar to be 28 mm in outer diameter,
Further, on the outer periphery, the surface layer formed in Example 4 was 50 μm thick.
Using the coated roller, the image was observed while changing the primary transfer bias. As a result, in a high-temperature and high-humidity environment, a sufficient image density was obtained at a DC voltage of 0.8 kv. Thereafter, even when a DC voltage of 5.0 kv was applied, image omission and scattering of the developer hardly occurred. Further, after an image was formed at a DC voltage of 5.0 kv using a postcard made of a transfer material as an official postcard, the image was confirmed on plain paper, but no afterimage phenomenon (a so-called ghost) was observed. Similarly, in a low-temperature and low-humidity environment, a sufficient image density was obtained with a DC voltage of 1.6 kV, and even when a DC voltage of 5.0 kV was applied, image omission and scattering of the developer hardly occurred. Further, after an image was formed at a DC voltage of 5.0 kv using a postcard made of a transfer material as an official postcard, the image was confirmed on plain paper, but no afterimage phenomenon (a so-called ghost) was observed.

(Comparative Example 1) A base layer in which carbon black having a volatile content of 0.2% was dispersed in silicon rubber by 4 parts by weight and a surface layer in which acrylic resin was dispersed by 8 parts by weight of carbon black having a volatile content of 5.0%. Was produced. Next, the results of measuring the electric resistance when a DC voltage of 500 V was applied for 10 seconds under each environment were as follows. Standard environment (22 ° C., 55%): 7 × 10 ⁵ Ω High temperature and high humidity environment (28 ° C., 85%): 5 × 10 ⁵ Ω Low temperature and low humidity environment (10 ° C., 15%): 8 × 10 ⁵ Ω

This charging roller was attached to the primary charging position 3-1 of the image forming apparatus using the process cartridge shown in FIG. 3, and a halftone image was evaluated under each environment in the same manner as in Example 2. As a result, in a high-temperature, high-humidity environment, the AC voltage was 1.1.
Sand image disappeared at kvpp, but AC voltage 1.8
When kvpp was applied, fine black streaks (so-called abnormal discharge) were observed. When the photosensitive drum was replaced with a photosensitive drum having 10 pinholes reaching the metal cylinder at equal intervals of 10 mm in the longitudinal direction and 5 mm in the circumferential direction, and an AC voltage of 2.0 kvpp was applied, excessive current flow (so-called pinhole) was performed. Leak) caused black bands on all pinholes.
Similarly, in a low-temperature and low-humidity environment, the sand image disappeared at 1.2 kvpp. However, when an AC voltage of 2.0 kvpp was applied, fine black streaks (so-called abnormal discharge) were observed.

Comparative Example 2 A semiconductive foamed roller was prepared in which carbon black having a volatile content of 5.0% was mixed with EPDM in an amount of 5 parts by weight in place of the composite metal oxide used in Example 3. The electric resistance in the thickness direction between the core metal and the roller surface of the obtained semiconductive foamed roller was measured by applying a DC voltage of 500 V for 10 seconds under each environment. The results are as follows. Standard environment (22 ° C., 55%): 5 × 10 ⁹ Ω High temperature and high humidity environment (28 ° C., 85%): 9 × 10 ⁸ Ω Low temperature and low humidity environment (10 ° C., 15%): 1 × 10 ¹⁰ Ω The hardness was 42 ° (Asker-C hardness meter, 1 kg load).

Next, the obtained semiconductive foamed roller is shown in FIG.
At the position of the transfer roller (5-7) of the image forming apparatus using the process cartridge shown in (1), the change of the halftone image with respect to the increase of the DC voltage was observed in the same manner as in Example 3. Although a sufficient image density was obtained with a DC voltage of 0.7 kV, a DC voltage of 2.0 kV was thereafter used.
Image loss occurred when v was applied. Further, scattering of the developer was also observed. Further, after an image was formed using a transfer material as an official postcard and a DC voltage of 2.0 kv, the image was confirmed on plain paper, and an afterimage phenomenon (a so-called ghost) was observed. Similarly, in a low-temperature and low-humidity environment, a sufficient image density was obtained at a DC voltage of 1.5 kv, but thereafter, a DC voltage of 3.0 kv was obtained.
When the voltage was applied, image omission and scattering of the developer occurred. Furthermore, the transfer material is a postcard made of government and a DC voltage of 3.0 kv
After the image was formed on the sheet, the image was confirmed on plain paper, and an afterimage phenomenon (a so-called ghost) was observed.

Comparative Example 3 A polyimide varnish for a heat-resistant film (U Varnish-S Co., Ltd. U-varnish-S) was replaced with zinc oxide (Z
nO) and aluminum oxide (Al2 O3), a powder composed of two kinds of oxides (ZnO.Al2 O3, that is, a composite composed of two kinds of metal oxides, whose volume resistivity is 2 × 10 ² Ωcm) Metal oxide) and volatile matter 2
5% by weight of 0% carbon color Black FW200 (manufactured by Degussa Co., Ltd.) was mixed and sufficiently mixed with a mixer to produce a seamless intermediate transfer belt of 80 μm in the same manner as in Example 5. The surface resistivity and volume resistivity of the obtained belt were measured by applying a DC voltage of 500 V for 10 seconds under each environment. The results were as follows. Standard environment (22 ° C., 55%): 3 × 10 ¹¹ Ω / □ and 4 × 10 ⁹ Ωcm High temperature and high humidity environment (28 ° C., 85%): 9 × 10 ¹⁰ Ω / □ and 1 × 10 ⁹ Ωcm Low temperature and low humidity Environment (10 ° C., 15%): 1 × 10 ¹² Ω / □ and 7 × 10 ⁹ Ωcm

Next, when the belt obtained in the image forming apparatus used in Example 5 was mounted and similarly evaluated, a sufficient image density was obtained at a DC voltage of 0.8 kV under a high temperature and high humidity environment. At the point of time when a DC voltage of 1.4 kv was applied, image omission and scattering of the developer occurred violently. Further, after an image was formed with a transfer material as an official postcard and a DC voltage of 1.4 kv, the image was confirmed on plain paper.
Ghost) was observed. Similarly, in a low-temperature and low-humidity environment, a sufficient image density was obtained with a DC voltage of 1.6 kv, but when a DC voltage of 2.0 kv was subsequently applied, image omission and scattering of the developer occurred. When an image was formed on a postcard made of a government-made postcard at a DC voltage of 2.0 kv and the image was confirmed on plain paper, an afterimage phenomenon (a so-called ghost) was observed.

(Modification) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and does not depart from the present invention described in the claims. Various design changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention is also applicable to a pre-transfer charge removing roller, a cleaning charge removing roller, and the like.

[0079]

According to the present invention, the following effects can be obtained. (E01) Since the charge providing member contains a composite metal oxide composed of three or more metal oxides, the electric resistance region required for each charge providing member can always be stably produced, In addition, the resistance variation due to the environment is small, and an effect of suppressing an excessive current accompanying an increase in the applied voltage can be provided. Therefore, it is possible to easily realize a semi-conductive electric resistance region required for various charge applying members, and the electric resistance variation due to the use environment is extremely small. And a transfer device and an image forming apparatus using the same, which can expand the range of the applied bias for obtaining a good image by the action of suppressing the occurrence of the charge.

[Brief description of the drawings]

FIG. 1 is a view showing a configuration example in which the present invention is applied to a roller-shaped charge applying member, and FIG. 1A is a diagram in which only one base layer containing a composite metal oxide is formed on the surface of a cored bar. 1B shows a configuration in which the surface of the base layer in FIG. 1A is covered with a surface layer, and FIG. 1C shows a configuration in which the surface of the base layer in FIG. 1A is sequentially covered with a protective layer and a surface layer.

FIG. 2 is a diagram showing a configuration example in which the present invention is applied to a belt-shaped charge applying member. FIG. 2A is a configuration of only a base layer containing a composite metal oxide, and FIG. 2B is a diagram of FIG. FIG. 2C shows a configuration in which the base layer surface is covered with a surface layer, and FIG.
Shows a configuration in which a surface layer is formed on the surface of a base layer via an adhesive layer.

FIG. 3 is a graph showing the relationship between the added amount of various fillers and the volume resistivity.

FIG. 4 is a graph showing the relationship between the added amount of various fillers and the volume resistivity.

FIG. 5 is a schematic explanatory view of an image forming apparatus using a process cartridge.

FIG. 6 shows an image bearing member having a process speed of 68 mm / sec on the charging roller manufactured in Example 2;
It is a figure which shows the change of the amount of electric current with respect to the increase of the alternating current voltage superimposed and applied with the frequency of 485Hz to the direct current voltage of -500v under each environment.

FIG. 7 is a DC voltage when a DC voltage is applied to the transfer roller manufactured in the third embodiment while passing a transfer material (plain paper) between the transfer roller and an image carrier having a process speed of 68 mm / sec. Is a measured value of a change in the amount of current with respect to an increase in.

FIG. 8 is a schematic explanatory view of an image forming apparatus having a transfer conveyance belt.

FIG. 9 is a schematic explanatory view of an image forming apparatus provided with an intermediate transfer belt B.

[Explanation of symbols]

R1: roller-shaped charge applying member; R1a: cored bar; R1b:
Base layer, R1c: Surface layer, R1d: Protective layer, R2: Belt-shaped charge applying member, R2a: Base layer, R2b: Surface layer, R2c: Adhesive layer, K: Process cartridge, Q1: Charging position, Q2
... Latent image writing position, Q3 ... Development area, Q4 ... Transfer area (primary transfer area), ROS ... Latent image latent image writing apparatus, S ... Transfer material (recording sheet), U ... Image recording apparatus, 1 ... Image carrier, 2
... Charging roller, 3a ... Developing roller, 3 ... Developing device, 4a ...
Cleaning blade, 4 ... cleaner, 5 ... static eliminator, 7
... Paper feed tray, 8 ... Pickup roller, 9 ... Separation roller, 10 ... Transfer roller, 11 ... Fixer, 12 ... Discharge roller, 13 ... Discharge tray, B ... Transfer and conveyance belt,
Q2c: latent image writing position, 21: drive roller, 21 to 24 ...
Belt support roller, 25 ... Suction roller, 26k-26c ...
Image carrier, 27k to 27c ... Charging roller, 28k to 28c ...
Developing device, Tk to Tc transfer roller, 29k to 29c cleaner, B intermediate transfer belt, L laser beam, Q5 2
Next transfer area, T1: primary transfer roll, T2: secondary transfer unit,
31 image carrier, 32 charging roller, 33 developing device
33k to 33c: developing unit, 34: cleaner, 35: static eliminator, 36: driving roll, 37 to 39: driven roll, 36
-40: belt support roll, 40: inner secondary transfer roll, 41: outer secondary transfer roll, 42: cleaning blade, 43: paper feed tray, 44: belt cleaner, 4
5: Fixing device.

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[Procedure amendment]

[Submission date] April 23, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0069

[Correction method] Change

[Correction contents]

The rotating image carrier 31 is transferred by the cleaner 34 after the toner images sequentially formed on the surface thereof are successively transferred onto the intermediate transfer belt B by the primary transfer roll T1 in the primary transfer area Q4. Cleaned,
Next, after the charge is removed by the charge remover 35, the charging roller 3
2 to be recharged. The intermediate transfer belt B is rotatably supported by a plurality of belt support rolls 36 to 40 including a driving roll 36, driven rolls 37 to 39, and an inner secondary transfer roll 40. In the region Q4, the toner images of the respective colors K, Y, M, and C are sequentially primary-transferred. The inner secondary transfer roll 4
0 and an outer secondary transfer roll 41 disposed opposite to the inner secondary transfer roll 40 with the intermediate transfer belt B interposed therebetween, to constitute a secondary transfer device T2. A secondary transfer area Q5 is formed in a contact area of the secondary transfer roll 41. A cleaning blade 42 made of polyurethane, silicon, or the like is always in contact with the outer secondary transfer roll 41, and foreign matters such as toner particles and paper dust adhered are removed.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

Claims (15)

[Claims] 1. A charge providing member comprising at least a composite metal oxide composed of three or more metal oxides. 2. The composite metal oxide powder composed of the three or more metal oxides has an electric resistivity of 1 × 10 ⁵ Ω.
2. The charge applying member according to claim 1, wherein the charge application member is not less than cm. 3. A charge providing member comprising at least a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more. 4. A charging member for charging the surface of an image carrier that is rotated while the electrostatic latent image is formed and then developed into a toner image after being uniformly charged. The charge applying member according to any one of claims 1 to 3, wherein 5. The image forming apparatus according to claim 1, wherein the charge applying member is arranged along a surface of the image carrier on which the toner image is formed while rotating and moving, and forms a transfer area between the image carrier and the image carrier. 4. The charge applying member according to claim 1, wherein the transfer member transfers a toner image on the surface of the image carrier to a surface of a transfer material passing through the transfer area. 6. The transfer in which the toner image on the surface of the image carrier is transferred to a toner image transfer area set along the surface of the image carrier on which the toner image is formed while rotating and moving the charge applying member. The charge applying member according to any one of claims 1 to 3, which is a transfer conveyance member that electrostatically attracts and conveys the material. 7. The toner image on the surface of the image carrier is primarily transferred in a primary transfer area set along the surface of the image carrier on which the toner image is formed while rotating and moving the charge applying member. 4. The charge applying member according to claim 1, wherein the primary transfer toner image is an intermediate transfer member that is secondarily transferred to a transfer material in a secondary transfer area. 8. The image forming apparatus according to claim 1, wherein the charge applying member is arranged along a surface of the image carrier on which the toner image is formed while rotating, and passes an intermediate transfer member rotating between the image carrier and the image carrier. The charge according to any one of claims 1 to 3, wherein the charge is a primary transfer member that forms a secondary transfer region and primary-transfers the toner image on the surface of the image carrier onto the surface of the intermediate transfer member that passes through the primary transfer region. Imparting member. 9. The image forming apparatus according to claim 1, wherein the charge applying member is configured to rotate and move the toner image primarily transferred by the primary transfer member onto the intermediate transfer member surface from the surface of the image carrier on which the toner image is formed. 4. The charge applying member according to claim 1, which is a secondary transfer member for performing a next transfer. 10. A rotating image carrier, a charging member for charging the surface of the image carrier, developing means for developing a latent image formed on the surface of the image carrier with toner, and a surface of the image carrier. Wherein the charging member is a composite metal oxide composed of three or more metal oxides, or a composite metal oxide composed of three or more metal oxides. And a carbon black having a volatile content of 1.5% or more. 11. A toner image forming means having a charging member for charging a surface of a rotating image carrier and forming a toner image on the charged surface of the image carrier, and disposed along the surface of the image carrier. An image forming apparatus that forms a transfer area for allowing a transfer material to pass between the image carrier and the surface of the transfer medium that passes through the transfer area; In the above, one or both of the charging member and the transfer member are 3
A composite metal oxide composed of at least one kind of metal oxide,
Alternatively, an image forming apparatus comprising at least a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more. 12. A transfer material on which a toner image on the surface of the image carrier is transferred is electrostatically attracted to a toner image transfer area set along the surface of the image carrier on which the toner image is formed while rotating and moving. Transfer member, an electrostatic attraction member for electrostatically adsorbing a transfer material to the transfer member, and a transfer member disposed on a back surface of the transfer material attraction surface of the transfer member to transfer a toner image onto the transfer material. A transfer metal member, an electrostatic attraction member, or a transfer member, wherein at least one of the transfer member, the transfer member, and the transfer member is composed of three or more metal oxides, or three or more metal oxides. A transfer device comprising at least a composite metal oxide constituted by a material and carbon black having a volatile content of 1.5% or more. 13. A charging member for charging a surface of an image carrier which is rotated while rotating, while being uniformly charged and then an electrostatic latent image is formed to develop the electrostatic latent image into a toner image, and a surface of the image carrier. A transfer material for electrostatically attracting and transferring a transfer material on which the toner image on the surface of the image carrier is transferred to a toner image transfer area set along the transfer member; and electrostatically attracting the transfer material to the transfer material. And a transfer member disposed on the back surface of the transfer material suction surface of the transfer conveyance member and transferring a toner image to a transfer material, wherein the charging member, the transfer conveyance member, Any one or all of the electrostatic adsorption member and the transfer member may be a composite metal oxide composed of three or more metal oxides, or a composite metal oxide composed of three or more metal oxides and volatile components. 1.5% or more cars An image forming apparatus characterized by comprising a down black least. 14. A primary transfer area, which is arranged along the surface of an image carrier on which a toner image is formed while rotating and moving, and through which an intermediate transfer member rotating and moving with the surface of the image carrier is formed. A primary transfer member for primary-transferring the toner image on the surface of the image carrier to the surface of the intermediate transfer member passing through the primary transfer region; and an inner side 2 for supporting a back surface of the rotating intermediate transfer member.
A secondary transfer voltage is applied to the inner secondary transfer member by contacting the outer transfer member and the inner secondary transfer member which are disposed opposite to the inner secondary transfer member with the next transfer member, the intermediate transfer member interposed therebetween. And a secondary transfer member for secondary-transferring a toner image primary-transferred onto the surface of the intermediate transfer member by the primary transfer member to the surface of a transfer material. A composite metal oxide in which any or all of the intermediate transfer member, the primary transfer member, the inner secondary transfer member, the outer secondary transfer member, or the electrode member is composed of three or more metal oxides Or a transfer device comprising at least a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more. 15. A charging member for charging a surface of an image carrier which is rotated while rotating, while the electrostatic latent image is formed into a toner image after being uniformly charged, and the image carrier. A primary transfer area that is arranged along the surface and passes through an intermediate transfer member that rotates and moves between the image carrier and the surface of the image carrier; and the image carrier is formed on the surface of the intermediate transfer member that passes through the primary transfer area. A primary transfer member for primary transfer of a toner image on a front surface, and an inner side 2 for supporting a back surface of the rotating intermediate transfer member.
A secondary transfer voltage is applied to the inner secondary transfer member by contacting the outer transfer member and the inner secondary transfer member which are disposed opposite to the inner secondary transfer member with the next transfer member, the intermediate transfer member interposed therebetween. And a secondary transfer member for secondary-transferring a toner image primary-transferred onto the surface of the intermediate transfer member by the primary transfer member to the surface of a transfer material. A composite metal oxide in which any or all of the charging member, the intermediate transfer member, the primary transfer member, the inner secondary transfer member, the outer secondary transfer member, and the electrode member are composed of three or more metal oxides. An image forming apparatus characterized by containing at least a compound or a composite metal oxide composed of three or more metal oxides and carbon black having a volatile content of 1.5% or more.