JP6929742B2 - Conductive members for electrophotographic and their manufacturing methods, process cartridges, and electrophotographic equipment - Google Patents

Description

The present invention relates to a conductive member for electrophotographic and a method for manufacturing the same, a process cartridge, and an electrophotographic apparatus.

In an electrophotographic apparatus which is an image forming apparatus adopting an electrophotographic method, a conductive member is used for various purposes, for example, as a conductive roller such as a charging roller, a developing roller, and a transfer roller. These conductive members are required to maintain an appropriate electric resistance value regardless of the usage environment, and in order to adjust the conductivity of the conductive layer, an electronic conductive agent typified by carbon black, etc. A conductive layer to which an ionic conductive agent such as a quaternary ammonium salt compound is added is provided. When the conductive roller is a charging roller, the discharge from the charging roller to the photoconductor is not stable because the charging roller is out of the proper resistance region, and excessive discharge is locally generated, resulting in a white-out image. Image defects such as may occur. To solve this problem, Patent Document 1 provides a conductive member having a surface layer made of a three-dimensionally continuous skeleton and a porous body having a co-continuous structure with pores.

Japanese Unexamined Patent Publication No. 2015-068987

According to the study by the present inventors, when the conductive member according to Patent Document 1 is used as a charging roller, abnormal discharge is suppressed by miniaturization of discharge, and surface charge is increased due to insulation and a large surface area. It was found that the discharge capacity was improved. It was also confirmed that dirt adhesion was suppressed. However, when the conductive member is used as a charging member for forming an electrophotographic image for a long period of time, the amount of accumulated charge on the surface may gradually decrease. When the amount of accumulated surface charge decreases, the surface of the photoconductor may not be sufficiently charged. In addition, dirt may easily adhere to the surface. When the conductive member is used as a transfer roller, the same problem may occur.

One aspect of the present invention is to provide a conductive member for electrophotographic capable of stably forming a high-quality electrophotographic image even after long-term use. Another aspect of the present invention is to provide a process cartridge and an electrophotographic apparatus capable of stably forming a high-quality electrophotographic image.

According to one aspect of the present invention, a conductive member for electrophotographic having a conductive support, an intermediate layer on the conductive support, and a surface layer on the intermediate layer.
The intermediate layer is non-conductive and contains a radiation decay type resin A.
The surface layer is a porous body, and a conductive member for electrophotographic that satisfies the following conditions (1), (2) and (3) is provided:
(1) The porous body has a co-continuous structure including a three-dimensionally continuous skeleton and three-dimensionally continuous pores;
(2) When an arbitrary 150 μm square region on the surface of the surface layer is photographed and the region is divided vertically into 15 equal parts and horizontally into 15 equal parts, the number of square groups consisting only of the skeleton and the fineness thereof. The sum with the number of squares consisting only of holes is 25% or less of the total number of squares;
(3) The surface layer is non-conductive.

According to another aspect of the present invention, the method for manufacturing a conductive member for electrophotographic.
Provided is a method for producing a conductive member for electrophotographic, which comprises a step of forming the porous body of the surface layer by phase separation of a polymer material and a solvent.

According to another aspect of the present invention, there is provided a process cartridge that is detachably configured on the main body of the electrophotographic apparatus and is characterized by including the conductive member.

According to still another aspect of the present invention, an electrophotographic apparatus including the conductive member is provided.

According to one aspect of the present invention, it is possible to provide a conductive member for electrophotographic capable of stably forming a high-quality electrophotographic image even after long-term use. Further, according to another aspect of the present invention, it is possible to provide a process cartridge and an electrophotographic apparatus capable of stably forming a high-quality electrophotographic image.

It is explanatory drawing of the estimation mechanism of the increase of dirt adhesion. It is explanatory drawing of the suppression mechanism of electrostatic adhesion of dirt. It is sectional drawing which shows an example of the conductive member which concerns on one aspect of this invention. It is explanatory drawing which shows an example of the evaluation method of the fineness of the porous body of a surface layer. It is a schematic diagram which shows an example of the conductive member which concerns on one aspect of this invention which introduced the separating member. It is a schematic diagram which shows an example of the process cartridge which concerns on one aspect of this invention. It is a schematic diagram which shows an example of the electrophotographic apparatus which concerns on one aspect of this invention. It is a schematic diagram which shows an example of the corona discharge treatment performed in confirmation of the radiation disintegration property of a resin.

[Conductive member for electrophotographic]
The conductive member for electrophotographic according to one aspect of the present invention has a conductive support, an intermediate layer on the conductive support, and a surface layer on the intermediate layer. Here, the intermediate layer is non-conductive and contains a radiation-disintegrating resin A. Further, the surface layer is a porous body and satisfies the following conditions (1), (2) and (3):
(1) The porous body has a co-continuous structure including a three-dimensionally continuous skeleton and three-dimensionally continuous pores;
(2) When an arbitrary 150 μm square region on the surface of the surface layer is photographed and the region is divided vertically into 15 equal parts and horizontally into 15 equal parts, the number of square groups consisting only of the skeleton and the fineness thereof. The sum with the number of squares consisting only of holes is 25% or less of the total number of squares;
(3) The surface layer is non-conductive.

Hereinafter, embodiments for carrying out the present invention will be described in detail exemplarily with reference to the drawings. However, the following description does not limit the technical scope of the present invention to the following embodiments.

In order to charge a charged member such as a photosensitive drum with a charging member, it is required to apply a voltage to the charging member to generate an electric discharge between the surface of the charging member and the surface of the photosensitive drum. Discharge is an electron avalanche diffusion phenomenon that occurs according to Paschen's law and increases exponentially while repeating the process of ionized electrons colliding with molecules and electrodes in the air to generate electrons and cations. This electron avalanche diffuses according to the electric field, and the degree of this diffusion determines the final amount of discharge charge.

In recent years, there has been a demand for even higher definition of image quality in electrophotographic image forming apparatus. For that purpose, a method of increasing the color gradation by increasing the charging voltage and increasing the development contrast can be considered. However, when the charging voltage is increased, the amount of discharge charge also increases, so that the amount of discharge charge locally increases due to resistance unevenness in the charged member, causing abnormal discharge, and there is a possibility that a white-out image may occur.

Especially in a high temperature and high humidity environment, the vibration of oxygen molecules and nitrogen molecules in the air becomes active, so that the mean free path of the electron avalanche becomes short. As a result, the amount of discharge charge increases, and the occurrence of white spot images due to abnormal discharge may become remarkable.

The present inventors have found that by providing a surface layer made of a porous body that is non-conductive and has a three-dimensionally co-continuous structure, abnormal discharge can be suppressed and white-out images can be suppressed. .. The reason for this is speculated as follows from the results of the examination. In the surface layer, the fine pores formed by the three-dimensionally continuous fine skeleton have a plurality of branches, and the branch has a plurality of locations connected to the surface of the conductive support, so that the normal discharge occurs. Can be suppressed from growing to the size of an abnormal discharge. In addition, although the pores communicate in the thickness direction, the presence of through holes penetrating in the same direction as the electric field is reduced as much as possible, and the skeleton exists before the discharge progresses, so that the discharge is divided. The amount of discharge charge can be reduced. As a result, it is presumed that the whiteout image can be suppressed without the discharge growing to an abnormal discharge. As a result of directly observing the discharge actually generated between the conductive member and the photosensitive drum using a high-sensitivity camera, when the surface layer, which is a porous body, is present on the surface of the conductive member, a single discharge occurs. The phenomenon of subdivision has been confirmed.

In the electrophotographic process, toner and toner externals, so-called stains, electrostatically or physically adhere to the charged member. Since dirt is a highly resistant material, if it adheres to the surface of a charged member, it causes uneven resistance. As a result, since the amount of discharge charge differs between the portion with the stain and the portion without the stain, it may be observed as an image defect.

The above phenomenon will be described with reference to FIG. 1 in the case of negative charging. The charging member 10 is connected to the power supply 13 and faces the photosensitive drum 11 grounded to the ground 14. An electric discharge is generated in the gap between the charging member 10 and the photosensitive drum 11, and negative-polarity electrons are attracted to the photosensitive drum 11 and positive-polarity ions are attracted to the surface of the charging member 10 according to the electric field. At this time, if the dirt 12 is present on the surface of the charging member 10, the positively polar ions attracted to the charging member 10 adhere to the dirt 12, and the dirt 12 is positively charged. As a result, the electrostatic attraction between the dirt 12 and the negatively charged charging member 10 increases, and the dirt 12 strongly adheres to the surface of the charging member 10. Further, since this phenomenon is repeated as the use progresses, the adhesive force of the dirt 12 continues to increase. Since the attached stain 12 has high resistance unevenness, the amount of discharge charge to the photosensitive drum 11 is smaller in the attached portion of the stain 12 than in the other portions, and the stain 12 appears as a black spot image in the halftone image.

Next, the suppression of dirt adhesion will be described. First, dirt adheres to the surface of the conductive member by physical adhesive force or electrostatic attraction. In particular, the dirt that rushes into the charging member has a charge distribution from plus to minus, so electrostatic adhesion of dirt is unavoidable. Further, as described above, in the conventional conductive member, ions having a polarity opposite to the applied voltage are attached to the surface and deposits of the charged member by electric discharge. Therefore, as the electric discharge is received, the electrostatic adhesive force increases, and the dirt once attached is hard to be peeled off.

The present inventors can prevent both physical adhesion and electrostatic adhesion of stains as described above by providing a surface layer made of a porous body that is non-conductive and has a three-dimensionally co-continuous structure. It was found that it can be suppressed. The reason for this is speculated as follows from the results of the examination. First, regarding physical adhesion, since the surface layer is a porous body having a fine skeleton and pores, the contact point can be made very small, and physical adhesion of dirt can be suppressed.

Next, the suppression of electrostatic adhesion will be described with reference to FIG. FIG. 2 is a schematic view of the charging member 21 and the photosensitive drum 22 in the case of negative charging. When a discharge occurs, the negative charge 24 propagates to the surface of the photosensitive drum 22 according to the electric field, and the positive charge 23 propagates to the surface layer 20. At this time, since the surface layer 20 is non-conductive, the positive polarity charge 23 is captured and the surface layer 20 is positively charged up. At this time, since the positively charged dirt that tends to adhere to the surface of the charging member 21 due to the electric field is electrostatically repelled, the electrostatic attraction acting on the dirt can be reduced. That is, it is possible to reduce electrostatic adhesion, which has been difficult to suppress in the past. Further, even if dirt adheres to the surface of the surface layer 20, since the surface layer 20 is a porous body, the dirt adhered electrostatically can be discharged. Specifically, when the electric discharge inside the porous body generated in the pores irradiates the dirt adhering to the surface of the surface layer 20, the polarity of the dirt can be changed negatively, so that the dirt works. The direction of electrostatic attraction is reversed, and dirt is peeled off by the electric field. That is, physical adhesion and electrostatic adhesion of dirt can be efficiently suppressed at the same time. As a result, it is presumed that black spots, which are image defects caused by dirt adhesion, can be reduced.

Considering long-term use, the following phenomena may occur. In the discharge for the purpose of charging in the electrophotographic field, hundreds to thousands of volts are applied to the charging member side. Therefore, at the time of discharge, a large amount of energy is applied locally on the surface of the charged member even if the amount of charged charge is within the range of normal discharge. In particular, in the present invention, the surface layer has a fine porous structure having a large surface area, and the energy received per unit area is large.

When the above-mentioned large discharge energy is continuously applied to the resin forming the surface layer, the bonds such as carbon-hydrogen in the polymer skeleton in the molecular chemical structure are partially broken, and radicals are generated. Normally, when this radical portion reacts with oxygen or water existing in the air, oxygen is taken into the chemical structure and oxidation proceeds. In addition, it forms a new bond with other radicals existing around the molecule, and a by-product is produced as a by-product. In particular, under high temperature and high humidity conditions, the oxidation is likely to proceed, and the amount of by-products of the by-products increases. This is because the motility of the resin molecules increases at high temperatures and the reaction with surrounding molecules proceeds, and at high humidity, oxidation is promoted due to the increase of water molecules. As a result, the non-conductive nature of the surface layer may decrease, the accumulated charge may leak to the conductive support, and the amount of accumulated charge may decrease. When the amount of accumulated charge decreases, the discharge capacity decreases, and image defects due to poor charging may occur. In addition, image defects due to dirt adhesion may occur.

As a result of diligent studies, the present inventors have found that when a large amount of energy is applied to the resin due to a long-term discharge, the behavior of the conductive member is related to the radiation-related properties of the resin. The present inventors have found that the durability of a conductive member can be improved by providing a non-conductive intermediate layer containing a radiation-disintegrating resin. The reason is considered as follows.

Radicals generated by radiation-disintegrating resin are unstable due to exposure to electric discharge, and cannot stay stably at the place where radicals are generated and move to the surroundings, resulting in a chemical reaction linked to the surrounding chemical structure. The source radical itself tends to terminate the reaction immediately. In the radiation-disintegrating resin constituting the intermediate layer, radicals generated in the chemical structure move on the main clavicle, and molecular cleavage that cleaves the main clavicle is likely to occur. This molecular cleavage is likely to occur near the end of the skeleton, and the cleavage terminates the radical reaction of the main skeleton (the skeleton with the longer molecular chain) after cleavage. The skeleton separated from the main skeleton after cleavage (the skeleton having the shorter molecular chain) is decomposed by a further reaction, disappears by gasification, and the entire radical reaction is terminated. The main skeleton after cleavage has a slight decrease in molecular weight, but other than that, there is no significant change compared to the original polymer skeleton structure.

In this way, since radical generation to termination of the reaction occur immediately, oxidation and by-product reaction of by-products are unlikely to proceed regardless of the conditions of use. As a result, when the intermediate layer containing the radiation-disintegrating resin is provided, oxidation of the material and by-products of by-products are suppressed even when exposed to electric discharge for a long time in a high-temperature and high-humidity environment. Therefore, the reduction in resistance can be suppressed, and the leakage of the accumulated charge to the conductive support can be reduced. As a result, the discharge stability and the effect of suppressing dirt adhesion can be maintained for a long period of time.

For the above reasons, according to the present invention, it is possible to provide a conductive member capable of achieving both suppression of image defects due to a decrease in discharge capacity and suppression of image defects due to stain adhesion. Further, according to the present invention, it is possible to provide a process cartridge and an electrophotographic apparatus capable of suppressing image defects due to poor charging for a long period of time and suppressing image defects due to stain adhesion.

Hereinafter, the present invention will be described in detail. Hereinafter, the conductive member for electrophotographic will be described with reference to a charging member (charging roller) which is a typical example thereof, but the application of the conductive member is not limited to the charging member (charging roller).

(Construction of conductive member)
3 (a) and 3 (b) show cross-sectional views of an example of the conductive member. The conductive member shown in FIG. 3A is composed of a conductive support 32, an intermediate layer 33, and a surface layer 31. The conductive support 32 is made of a core metal as a conductive shaft core. The intermediate layer 33 is formed on the outside of the conductive support 32, contains a radiation-disintegrating resin A, and is non-conductive. The surface layer 31 is formed on the outer periphery of the intermediate layer 33 and is a porous body.

The conductive member shown in FIG. 3B is composed of a conductive support, an intermediate layer 33, and a surface layer 31. The conductive support is composed of a core metal as the conductive shaft core 32 and a conductive resin layer 34 provided on the outer periphery thereof. The intermediate layer 33 is formed on the outside of the conductive resin layer 34, contains a radiation-disintegrating resin A, and is non-conductive. The surface layer 31 is formed on the outer periphery of the intermediate layer 33 and is a porous body. The conductive member may have a multi-layer structure in which a plurality of conductive resin layers 34 are arranged, if necessary, as long as the effects of the present invention are not alienated. Further, the present conductive member is not limited to the roller shape, and may be, for example, a blade shape.

<Conductive support>
The conductive support may be made of a conductive shaft core as described above, or may be made of a conductive shaft core and a conductive resin layer on the conductive shaft core.

(1) Conductive shaft core body The conductive shaft core body can be appropriately selected and used from those known in the field of conductive members for electrophotographic. For example, a cylinder in which the surface of a carbon steel alloy is nickel-plated with a thickness of about 5 μm can be used. As the conductive shaft core, a metal shaft core is preferable. When a part of the energy at the time of discharge is converted into heat energy, the metal shaft core having high thermal conductivity easily releases the heat energy, the damage to the conductive member is reduced, and the durability is increased. Because.

(2) Conductive Resin Layer As a material constituting the conductive resin layer, a rubber material, a resin material, or the like can be used. The rubber material is not particularly limited, and a rubber material known in the field of conductive members for electrophotographic can be used, and specific examples thereof include the following. Epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary copolymer, acrylonitrile-butadiene copolymer, hydrogenated product of acrylonitrile-butadiene copolymer, silicone rubber, acrylic rubber and Urethane rubber, etc. As the resin material, a resin material known in the field of conductive members for electrophotographic can be used. Specific examples thereof include polyurethane resin, polyamide resin, polyester resin, polyolefin resin, epoxy resin, and silicone resin. These may be used alone or in combination of two or more. Among these, acrylonitrile-based rubber is preferable as the material constituting the conductive resin layer. When the material constituting the conductive resin layer is acrylonitrile-based rubber, the reactivity with the intermediate layer is poor even when energy is applied during discharge, and by-products of by-products and accompanying fluctuations in resistance value occur. This is because it is difficult.

An electronic conductivity-imparting agent or an ionic conductivity-imparting agent can be added to the material constituting the conductive resin layer, if necessary, in order to adjust the electric resistance value. Examples of the electron conductivity-imparting agent include carbon black and graphite exhibiting electron conductivity; oxides such as tin oxide; metals such as copper and silver; conductivity obtained by coating the surface of particles with oxides and metals. Sex particles can be mentioned. Examples of the ion conductivity-imparting agent include an ion conductivity-imparting agent having an ion exchange performance such as a quaternary ammonium salt showing ion conductivity and a sulfonate. These may be used alone or in combination of two or more. Further, as long as the effect of the present invention is not impaired, a filler, a softening agent, a processing aid, a tackifier, an anti-adhesive agent, a dispersant, a foaming agent, and a roughening agent generally used as a resin compounding agent are used. Particles and the like can be added.

The volume resistivity of the conductive resin layer ^{is preferably 1 × 10 3} Ω · cm or more and 1 × 10 ⁹ Ω · cm or less. It has been confirmed that the surface layer can suppress the occurrence of image defects due to excessive discharge even when the electric resistance value of the conductive support is sufficiently low.

<Middle class>
As described above, when energy due to discharge is applied to the conductive member, accumulated charge leaks from the surface layer to the conductive support due to oxidation and by-products of by-products, resulting in discharge stability and suppression of dirt adhesion. The effect of is reduced. As a result of diligent studies, the present inventors have found that by providing a non-conductive intermediate layer containing a radiation-disintegrating resin A, leakage of accumulated charges from the surface layer to the conductive support can be suppressed for a long period of time.

Since the influence of the electric discharge reaches the lowermost end of the surface layer on the intermediate layer side, the surface of the intermediate layer is exposed to the electric discharge. Here, the intermediate layer is non-conductive and contains a radiation-disintegrating resin A capable of suppressing oxidation due to electric discharge and by-products of by-products, so that high resistance can be maintained and the surface surface can be maintained. Even if the resistance value of the layer is lowered, the leakage of accumulated charges can be blocked. By suppressing the leakage of electric charges accumulated in the surface layer, it is possible to maintain the effects of discharge stability and dirt adhesion suppression for a long period of time. Further, by optimizing the volume resistivity of the intermediate layer as described later, the intermediate layer can also be charged up. As a result, the amount of charge-up as the conductive member can be raised, and the discharge stability and the effect of suppressing dirt adhesion can be further obtained. In the present invention, the radiation-disintegrating resin contained in the intermediate layer is formally referred to as "radiation-disintegrating resin A", and the radiation-disintegrating resin contained in the surface layer described later is referred to as "radiation-disintegrating resin B".

(1) Volume resistivity of the intermediate layer The intermediate layer is non-conductive in order to suppress leakage of accumulated charges to the conductive support. In the present invention, "non-conductive" means that the volume resistivity is 1 × 10 ¹⁰ Ω · cm or more. The volume resistivity of the intermediate layer ^{is preferably 1 × 10 12} Ω · cm or more and 1 × 10 ¹⁷ Ω · cm or less. When the volume resistivity is 1 × 10 ¹² Ω · cm or more, leakage of charges accumulated in the surface layer can be sufficiently suppressed. On the other hand, when the volume resistivity is 1 × 10 ¹⁷ Ω · cm or less, it is possible to sufficiently supply the electric charge of the intrapore discharge in the surface layer. Further, when the volume resistivity is 1 × 10 ¹⁵ Ω · cm or more and 1 × 10 ¹⁷ Ω · cm or less, the charge-up of the intermediate layer itself becomes large. Since the intermediate layer is integrated, it is more preferable to charge up the intermediate layer because the variation can be reduced and the dirt adhesion suppressing effect can be made uniform.

The non-conductive property of the intermediate layer is evaluated by the following method. The volume resistivity of the intermediate layer is measured in contact mode using a scanning probe microscope (SPM). Specifically, a test piece containing an intermediate layer is produced from a conductive member by a focused ion beam method. Next, the test piece is placed on a metal plate made of stainless steel to obtain a measurement section. Select a location that is in direct contact with the metal plate, bring the SPM cantilever into contact, apply a voltage of 50 V to the cantilever, and measure the current value. The volume resistivity is calculated from the thickness and current value of the measurement point of the test piece. The conductive member is divided into 10 regions in the longitudinal direction, and the above measurement is performed at an arbitrary 1 point from each region, for a total of 10 points, and the average value is taken as the volume resistivity of the intermediate layer. .. The volume resistivity of the intermediate layer after the durability evaluation, which will be described later, can also be measured in the same manner as described above.

(2) Material of the intermediate layer The intermediate layer is non-conductive and contains a radiation-disintegrating resin A. If the intermediate layer contains the radiation-disintegrating resin A and is non-conductive, the resistance does not decrease even if it receives a discharge as described above, so that the accumulated charge leaks between the surface layer and the conductive support. It becomes possible to shut off. As a result, the dirt adhesion suppressing effect can be maintained for a long period of time.

As the radiation-disintegrating resin A, for example, the radiation-disintegrating resin described on pages 89 to 91 of "Radiation and Polymers" by Kenichi Shinohara et al. (Maki Shoten, published in 1968) can be used. Specific examples thereof include poly-α-methylstyrene and cellulose acetate. In particular, the radiation-disintegrating resin A is preferably an acrylic resin having a structural unit represented by the following formula (1).

In the formula (1), R ₁ represents a hydrocarbon group having 1 to 6 carbon atoms. Since R ₁ is a hydrocarbon group having 1 to 6 carbon atoms, there are not too many portions that can be radicalized at the time of discharge, and oxidation that reacts with surrounding oxygen and water and by-products of by-products are unlikely to occur. Examples of the acrylic resin having the structural unit represented by the formula (1) include polymethylmethacrylate, ethylpolymethacrylate, propylpolymethacrylate, isopropylpolymethacrylate, butylpolymethacrylate, tertiarybutylbutylmethacrylate, and poly. Examples thereof include isobutyl methacrylate and cyclohexyl polymethacrylate. The acrylic resin may be a copolymer containing a plurality of structural units represented by the formula (1), and other monomer units may be used in addition to the structural units represented by the formula (1). It may be a copolymer containing.

The reaction mechanism that can be considered when the repeating unit of the radiation-disintegrating resin A is represented by the above formula (1) will be described using the following reaction formula (A). In the following reaction formula (A), n represents the number of repeating units and dots represent radicals. When energy is applied by electric discharge, hydrogen on the methyl group bonded to the polymer skeleton, which is the main chain, is separated to generate radicals. This radical generation is likely to occur near the end of the skeleton. The generated radicals are very unstable due to the electron-withdrawing action of the ester bond. Therefore, the next reaction, that is, the radical tries to move to another part. At that time, the radicals move toward the main clavicle due to the influence of the ester bond. Molecular cleavage occurs when the bond between the quaternary carbon to which the methyl group is bonded and the carbon adjacent to the main chain skeleton direction is broken and the carbon adjacent to the main chain skeleton direction is radicalized. After molecular cleavage, the main skeleton is divided into a skeleton with a shortened molecular chain, the reaction is terminated on the main skeleton side, and radicals remain on the skeleton side with a shortened molecular chain. In the skeleton on the side where radicals remain, decomposition proceeds by further reaction, radicals disappear by gasification, and the entire radical reaction ends. That is, it is considered that unstable radicals are formed and the reaction is terminated rapidly, so that the chances of reacting with surrounding oxygen and water are reduced and oxidation is suppressed.

_{R 1} in the formula (1) is preferably a linear or branched alkyl group having 2 or more and 6 or less carbon atoms. Since R ₁ does not have a cyclic structure, stable radical formation due to resonance or the like is suppressed, and since there are multiple carbons and three-dimensional obstacles increase, the chance of reaction with the discharge product in this portion is reduced, and oxidation is suppressed. NS.

_{It is more preferable that the R 1} in the formula (1) is at least one selected from the group consisting of the groups represented by the following formulas (2) to (5). Since R ₁ is at least one selected from the group consisting of the groups represented by the following formulas (2) to (5), there is no secondary carbon that easily becomes a radical on _{R 1, and steric hindrance becomes large.} This suppresses oxidation.
(2) -C (CH ₃ ) ₃ ,
(3) -CH (CH ₃ ) ₂ ,
(4) -CH (CH ₃ ) -C (CH ₃ ) ₃ ,
(5) -C (CH ₃ ) _2- CH (CH ₃ ) ₂ .

It is more preferable that _{R 1} in the formula (1) is −C (CH ₃ ) _3. Since R ₁ is −C (CH ₃ ) ₃ , the tertiary carbon is eliminated and the carbon is composed of quaternary carbon and primary carbon, and stable radicals are less likely to be formed, so that discharge deterioration due to oxidation is suppressed. Will be done. The term "quaternary carbon" means a carbon atom in which all the atoms to be bonded are atoms other than hydrogen atoms (specifically, carbon atoms and the like).

The weight average molecular weight of the radiation-disintegrating resin A is preferably 50,000 or more and 2.5 million or less. The glass transition temperature (Tg) of the radiation-disintegrating resin A is preferably −70 ° C. or higher and 250 ° C. or lower. The weight average molecular weight is a value measured by gel permeation chromatography (GPC). Further, Tg is a value measured by a method described later.

(3) Judgment of radiation-disintegrating type of resin Whether or not the resin is a radiation-disintegrating type resin can be determined by measuring the change in molecular weight before and after the treatment of applying radiation or energy corresponding to it. .. For example, a corona discharge is performed on the resin, and analysis is performed by gel permeation chromatography (GPC) measurement. In GPC measurement, the target resin is dissolved in a solvent to make a solution. Here, as the solvent, the target resin is most dissolved from toluene, chlorobenzene, tetrahydrofuran (THF), trifluoroacetic acid, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), formic acid and the like. Use an easy solvent. A solution is prepared by dissolving 1% by mass or more of the target resin in the solvent. Using the solution, GPC measurement of the dissolved target resin is performed. When the molecular weight is less than or equal to the molecular weight before the corona discharge treatment, it indicates that the molecular skeleton is preferentially cleaved, and it is judged to be a radiation decay type. On the other hand, when the molecular weight increases, it is judged to be a radiation crosslinked type.

(4) Thickness of the intermediate layer The thickness (thickness) of the intermediate layer is preferably 1 μm or more and 5 μm or less. When the film thickness is 1 μm or more, it is possible to suppress the electric charge accumulated in the surface layer from leaking to the conductive support, and the effect of suppressing dirt adhesion can be maintained. Further, when the film thickness is 5 μm or less, the electric charge is sufficiently accumulated, so that it is possible to suppress the charge defect caused by the insufficient discharge amount. The film thickness is more preferably 1.5 μm or more and 4.5 μm or less, and further preferably 2 μm or more and 4 μm or less.

The film thickness of the intermediate layer can be measured by cutting out a sheet with a sharp blade such as a razor or a manipulator so that the cross section of the intermediate layer is exposed, and observing this with an optical microscope or an electron microscope. When the maximum value of the film thickness is A and the minimum value is B, 1 μm ≦ B and A ≦ 5 μm are preferable. The conductive member is divided into 10 equal parts in the longitudinal direction, and the thickness of the intermediate layer is measured at any one location (10 locations in total) in each region of the obtained 10 regions, and the average value is calculated. The thickness of the intermediate layer.

(5) Structure of Intermediate Layer The structure of the intermediate layer is not particularly limited as long as the effects of the present invention are exhibited, and may be, for example, a solid film, a porous body, or the like, but a solid film is preferable. Since the intermediate layer is a solid film, the influence of the energy of the discharge is less likely to extend to the portion away from the surface layer, the resistance is less likely to be low in the portion close to the conductive support, and the conductive support of the accumulated charge is less likely to occur. Leakage to is suppressed.

(6) Method for Forming Intermediate Layer The intermediate layer can be formed on the conductive support by the following known methods. Coating methods such as dipping method, roll coating method, spray method, electrostatic coating method, tube molding method such as extrusion and multicolor molding, inflation molding method, blow molding method, lamination and combinations thereof. It is preferable to form the intermediate layer by the dipping method because it can be formed over the entire surface with a film thickness of 1 μm or more and 5 μm or less, and a uniform accumulated charge can be provided.

<Surface layer>
The surface layer is a porous body and satisfies the following conditions (1), (2) and (3).

(1) Co-continuous structure of the porous body of the surface layer The porous body of the surface layer has a co-continuous structure including a three-dimensionally continuous skeleton and three-dimensionally continuous pores. In order for the electric charge generated by the electric discharge in the porous body to reach the surface of the photosensitive drum, it is necessary that the pores are three-dimensionally continuous. Here, the three-dimensionally continuous pores indicate pores having the following two characteristics. First, the pores connect one opening on the surface of the surface layer with a plurality of other openings. Second, the pores have a plurality of branches, and the pores have a plurality of locations connected to the surface of the intermediate layer. Further, in order to construct a porous body having such pores, the skeleton also needs to be three-dimensionally continuous. Such a structure in which both the pores and the skeleton are three-dimensionally continuous is referred to as a co-continuous structure in the present invention. The porous body of the surface layer has a co-continuous structure, and the presence of multiple branches causes the discharge to proceed in the surface layer, and the skeleton exists at the point where it grows, and the skeleton divides the discharge, which is normal. It is possible to suppress the discharge from growing to an abnormal discharge. In addition, the contact area of dirt can be reduced to suppress the adhesion of dirt. Further, even if dirt adheres, the discharge charge that has passed through the pores adheres to the dirt, so that the charge of the dirt can be reversed and can be electrostatically peeled off. Since the discharge diffuses in a conical shape according to the direction of the electric field, if a thick and linear hole exists in the direction of the electric field, the discharge may grow to an abnormal discharge and a white-out image may occur. Therefore, it is preferable that the through holes arranged linearly in the same direction as the electric field, that is, in the thickness direction, are as small as possible and fine.

Whether or not the porous body of the surface layer has a co-continuous structure is determined by the SEM image obtained by a scanning electron microscope (SEM), the porous body obtained by a three-dimensional transmission electron microscope, an X-ray CT inspection device, or the like. It can be confirmed in the three-dimensional image of. That is, in the SEM image or the three-dimensional image, the skeleton may have a plurality of branches and may have a plurality of locations connected from the surface of the surface layer to the surface of the intermediate layer. Further, it may be confirmed that the pores connect the plurality of openings on the surface of the surface layer, have a plurality of branches, and reach the surface of the intermediate layer from the surface of the surface layer. The presence or absence of a co-continuous structure is specifically confirmed by a method described later.

(2) Fineness of the porous body of the surface layer The porous body of the surface layer has a fine structure. That is, when an arbitrary 150 μm square region on the surface of the surface layer is photographed and the region is divided vertically into 15 equal parts and horizontally into 15 equal parts, only the number of square groups consisting of only the skeleton and the pores are present. The total with the number of square groups consisting of is 25% or less of the total number of square groups. Since the surface area is increased by making the pores finer, it is possible to suppress the local application of energy during discharge. As a result, it is possible to suppress a local decrease in resistance value, and as a result, it is possible to suppress leakage of accumulated charges, and it is possible to suppress abnormal discharge.

The fineness is evaluated as follows. First, the surface layer is observed from the direction facing the surface layer, and an arbitrary 150 μm square region on the surface of the surface layer is photographed. At this time, a method capable of observing a region of 150 μm square, such as a laser microscope, an optical microscope, or an electron microscope, may be appropriately used. Next, as shown in FIG. 4, when the region is divided into 15 equal parts vertically and 15 equal parts horizontally, the total of the number of square groups consisting of only the skeleton and the number of square groups consisting of only pores is calculated. calculate. When the total is 25% or less of the total number of square groups, a decrease in resistance value due to local energy concentration during discharge in the pores is suppressed. It is preferable that the total is 15% or less of the total number of square groups because the decrease in resistance value can be further suppressed and the leakage of accumulated charge after long-term use becomes slight. When the total is 5% or less of the total number of square groups, local energy concentration during discharge is further suppressed, so that the effect of suppressing leakage of accumulated charges to the conductive support is further obtained. And more preferred. The lower limit of the total ratio is not particularly limited, and a smaller value is preferable. The evaluation of the fineness of the porous body of the surface layer is specifically carried out by the method described later.

(3) Volume resistivity of the surface layer The surface layer is non-conductive. As described above, “non-conductive” means that the volume resistivity is 1 × 10 ¹⁰ Ω · cm or more. Since the surface layer is non-conductive, the skeleton of the surface layer can capture and charge up ions having a polarity opposite to the charging voltage by electric discharge. When the surface layer is charged up, the adhesion of dirt can be reduced by electrostatic repulsion, and the attached dirt is irradiated with a discharge in the pores to reverse the charge of the dirt and peel it off. Can be done.

The volume resistivity of the surface layer is preferably 1 × 10 ¹² Ω · cm or more and 1 × 10 ¹⁷ Ω · cm or less. When the volume resistivity is 1 × 10 ¹² Ω · cm or more, the skeleton can be easily charged up and the adhesion of dirt can be further suppressed. On the other hand, when the volume resistivity is 1 × 10 ¹⁷ Ω · cm or less, the generation of electric discharge in the pores of the surface layer is promoted, and dirt can be easily and electrostatically peeled off. Further, when the volume resistivity is 1 × 10 ¹⁵ Ω ・ cm or more and 1 × 10 ¹⁷ Ω ・ cm or less, the influence of the variation in the charge-up of the surface layer is reduced, and the electrostatic peeling of dirt is further improved. It is more preferable because it can be further promoted.

The volume resistivity of the surface layer is measured as follows. First, from the surface layer existing on the surface of the conductive member, a region not containing pores is taken out as a test piece using tweezers. Next, the cantilever of the scanning probe microscope (SPM) is brought into contact with the cantilever, and the test piece is sandwiched between the cantilever and the conductive substrate to measure the volume resistivity. The longitudinal direction of the conductive member is divided into 10 equal parts, the volume resistivity is measured at any one location (10 locations in total) in each region of the obtained 10 regions, and the average value is the volume of the surface layer. Let it be the resistivity. Specifically, it can be measured by the method described later.

(4) Cross-sectional shape of the pores of the porous body of the surface layer If the porous body of the surface layer has a three-dimensionally continuous skeleton and three-dimensionally continuous pores, the cross section of the pores. The shape is not particularly limited, but may be, for example, a polygon such as a circle, an ellipse, or a quadrangle, or a semicircle. It is preferable that the surface area is large and the cross-sectional shape of the pores is not circular so as to secure a sufficient amount of discharge charge and disperse the energy at the time of discharge. In this case, the decrease in resistance of the surface layer is suppressed, the leakage of the accumulated charge to the conductive support is suppressed, and image defects due to stains are suppressed.

The cross-sectional shape of the pores as described above may be evaluated as follows. First, a smooth cross section of the surface layer is prepared using a microtome or the like, and this cross section is observed with an electron microscope to obtain a cross section image. Next, the cross-sectional image is image-processed to obtain a binarized image. Here, the pores of the actual porous body are three-dimensionally continuous, but the pore cross section in a certain cross-sectional view has a closed shape. Further, with respect to the pore cross section in the binarized image, the perimeter of each pore is L, the area of the pore is S, and the circularity K = L ² / 4πS is calculated. This circularity K indicates the complexity of the shape of the pores and skeleton. When the shape of the pores is a perfect circle, the value of K is 1, and the more complicated the shape, the larger the value of K. The units of L and S can be appropriately selected so that the unit of K disappears, that is, K becomes a constant.

When K is calculated for the pores in the binarized image, the arithmetic mean of K is preferably 2 or more. When the arithmetic mean of K is 2 or more, leakage of the accumulated charge to the conductive support can be sufficiently suppressed. Further, when the arithmetic mean of K is 3 or more, the increase of accumulated charges and the suppression of leakage are further advanced, and the generation of black spot images due to stains can be suppressed, which is more preferable. The arithmetic mean of K is more preferably 3.5 or more, and particularly preferably 4 or more. The upper limit of the arithmetic mean of K is not particularly limited, but can be, for example, 10 or less. The arithmetic mean of K is obtained by dividing the conductive member into 10 equal parts in the longitudinal direction, measuring K at any one location (10 locations in total) in each region of the obtained 10 regions, and averaging these. It is a value calculated by. Specifically, it can be measured by the method described later.

(5) Material of surface layer The material of the skeleton constituting the porous body of the surface layer is not particularly limited as long as the porous body can be formed, and the organic resin, silica, an inorganic material such as titania, and the organic resin are used. A material obtained by hybridizing the inorganic material can be used. Here, the organic resin refers to a material having a large molecular weight, and represents a polymer obtained by polymerizing a monomer such as a semi-synthetic polymer or a synthetic polymer, or a compound having a large molecular weight such as a natural polymer.

Examples of the organic resin include the following. Acrylic polymers; polyolefins such as polyethylene and polypropylene; polyimide; polyamides; polyamideimides; polyarylenes such as polyparaphenylene oxide and polyparaphenylene sulfides (aromatic polymers); polyvinyl ethers; polyvinyl alcohols; polyolefins, polystyrenes, polyimides , the polyarylenes (aromatic polymers), sulfonic acid _(-SO 3 H), carboxyl group (-COOH), a phosphoric acid group, a sulfonium group, ammonium group, or, those that have been introduced pyridinium groups, polytetra Fluorine-containing polymers such as fluoroethylene and polyvinylidene fluoride; perfluorosulfonic acid polymers in which a sulfonic acid group, a carboxyl group, a phosphoric acid group, a sulfonium group, an ammonium group, or a pyridinium group is introduced into the skeleton of the fluorine-containing polymer. Perfluorocarboxylic acid polymers, perfluorophosphate polymers; polybudadien compounds; polyurethane compounds such as elastomers and gels; epoxy compounds; silicone compounds; polyvinyl chloride; polyethylene terephthalates; (acetyl) cellulose; nylons; polyallylates ; Polymers, etc. These polymers may be used alone or in combination of two or more. Further, these polymers may have a specific functional group introduced into the polymer chain. Further, these polymers may be copolymers produced from a combination of two or more kinds of monomers which are raw materials for these polymers.

Examples of the inorganic material include oxides of Si, Mg, Al, Ti, Zr, V, Cr, Mn, Fe, Co, Ni, Cu, Sn and Zn. More specifically, the following metal oxides can be mentioned. Examples thereof include silica, titanium oxide, aluminum oxide, alumina sol, zirconium oxide, iron oxide and chromium oxide. One type of these inorganic materials may be used, or two or more types may be used in combination.

The surface layer preferably contains a radiation-disintegrating resin B. As described above, since the radiation-disintegrating type resin is unlikely to have a low resistance even when it receives the energy at the time of discharge, the porous body of the surface layer also contains the radiation-disintegrating type resin, so that the resistance to the discharge energy is further increased. Leakage of the accumulated charge to the conductive support is further suppressed. As a result, the effect of suppressing dirt adhesion can be maintained for a long period of time even under conditions in which the energy at the time of discharge is further increased.

The radiation-disintegrating resin B contained in the surface layer is preferably an acrylic resin having a structural unit represented by the following formula (6).

In formula (6), R ₆ represents a hydrocarbon group having 1 to 6 carbon atoms. Since R ₆ is a hydrocarbon group having 1 to 6 carbon atoms, there are not too many portions that can be radicalized at the time of discharge, and oxidation that reacts with surrounding oxygen and water and by-products of by-products are unlikely to occur. Examples of the acrylic resin having the structural unit represented by the formula (6) include polymethylmethacrylate, ethylpolymethacrylate, propylpolymethacrylate, isopropylpolymethacrylate, butylpolymethacrylate, tertiarybutylbutylmethacrylate, and poly. Examples thereof include isobutyl methacrylate and cyclohexyl polymethacrylate. The acrylic resin may be a copolymer containing a plurality of structural units represented by the formula (6), and other monomer units may be used in addition to the structural units represented by the formula (6). It may be a copolymer containing. The reaction mechanism that can be considered when the repeating unit of the radiation-disintegrating resin B is represented by the above formula (6) is described by the above-mentioned reaction formula (A) as in the case of the radiation-disintegrating resin A contained in the intermediate layer. That is, it is considered that unstable radicals are formed and the reaction is terminated rapidly, so that the chance of reacting with surrounding oxygen and water is reduced and oxidation is suppressed.

_{R 6} in the formula (6) is preferably a linear or branched alkyl group having 2 or more and 6 or less carbon atoms. Since R ₆ does not have a cyclic structure, stable radical formation due to resonance or the like is suppressed, and the number of carbons increases to increase steric obstacles, which reduces the chance of reaction with the discharge product in this portion and suppresses oxidation. NS. R ₆ is more preferably −C (CH ₃ ) _3. Since R ₆ is −C (CH ₃ ) ₃ , the tertiary carbon is eliminated and the carbon is composed of quaternary carbon and primary carbon, and stable radicals are less likely to be formed, so that discharge deterioration due to oxidation is suppressed. Will be done.

The weight average molecular weight of the radiation-disintegrating resin B is preferably 50,000 or more and 2.5 million or less. The glass transition temperature (Tg) of the radiation-disintegrating resin B is preferably 50 ° C. or higher and 250 ° C. or lower.

(6) Method for Forming Surface Layer The method for forming the surface layer is not particularly limited as long as the porous body can be formed as the surface layer, and examples thereof include the following methods. A method of forming a porous body by using phase separation of a polymer material solution, a method of forming a porous body by using a foaming agent, a method of irradiating an energy ray such as a laser to form a porous body, etc. .. Among these, a method utilizing phase separation of a polymer material solution is preferable because fine and complicated pores and skeletons can be formed. Here, the polymer material solution represents a solution containing a polymer material and a solvent. Examples of the method using the phase separation of the polymer material solution include the following three methods.
1. 1. Higher by mixing a plurality of polymer materials or precursors of the polymer materials and a solvent, and changing the temperature, humidity, solvent concentration, compatibility between the plurality of polymer materials due to the polymerization of the polymer materials, etc. Induces phase separation between molecular and polymer materials. Then, by removing one of the polymer materials, a porous body in which a continuous skeleton and continuous pores coexist is obtained.
2. By mixing a polymer material or a precursor of the polymer material with a solvent and changing the temperature, humidity, solvent concentration, compatibility between the polymer material and the solvent due to the polymerization of the polymer material, etc., the polymer material Induces phase separation between the solvent and the solvent. Then, by removing the solvent, a porous body in which a continuous skeleton and continuous pores coexist is obtained.
3. 3. A polymer material, water, a solvent, a surfactant and a polymerization initiator are mixed to prepare a water-in-oil emulsion. By polymerizing the polymer material in oil and then removing water, a porous body in which a continuous skeleton and continuous pores coexist is obtained.

Among these, the method of forming a porous body by phase separation of a polymer material and a solvent makes it easier to freeze the structure in the initial process of phase separation as compared with other methods, and as a result, it is porous. It is an effective method for finening the pores and the skeleton of the body, and is preferable. Further, it is preferable because the porous body easily forms a complicated shape characteristic of spinodal decomposition. That is, it is preferable that the method for producing a conductive member for electrophotographic photography includes a step of forming a porous body of a surface layer by phase separation between a polymer material and a solvent.

(7) Thickness of surface layer The thickness (film thickness) of the surface layer is preferably 1 μm or more and 30 μm or less. When the thickness of the surface layer is 1 μm or more, the skeleton is sufficiently charged up and abnormal discharge can be suppressed. Further, when the thickness of the surface layer is 30 μm or less, the discharge in the pores reaches the photosensitive drum, and the image can be formed without insufficient charging. The thickness of the surface layer is more preferably 1 μm or more and 20 μm or less, and further preferably 5 μm or more and 20 μm or less. When the thickness of the surface layer is 20 μm or less, the polarity of the dirt adhering to the surface layer can be suitably reversed, and image defects due to the dirt adhering can be further suppressed.

The thickness of the surface layer is confirmed as follows. A section including the intermediate layer and the surface layer is cut out from the conductive member, and the thickness of the surface layer is measured by performing X-ray CT measurement. Specifically, the two-dimensional slice image obtained by the X-ray CT measurement is binarized by the Otsu method to distinguish between the skeleton portion and the pore portion. In each of the binarized slice images, the ratio occupied by the skeleton part is quantified, the numerical value is confirmed from the conductive support side to the surface layer side, and the region where the ratio occupied by the skeleton part is 2% or more is defined as the surface layer. The outermost surface and the lowest surface of the surface layer are defined. Here, the "ratio occupied by the skeleton portion" means a value calculated by {(area of the skeleton portion) / (area of the skeleton portion + area of the pore portion)}. The longitudinal direction of the conductive member is divided into 10 equal parts, the thickness of the surface layer is measured at any one location (10 locations in total) in each region of the obtained 10 regions, and the average value thereof is taken as the surface layer. The thickness of. Specifically, it can be measured by the method described later.

(8) Porosity of the surface layer The porosity of the porous body of the surface layer may be as long as it does not impair the effect of the present invention, and specifically, it is preferably 40% or more and 95% or less. When the porosity is 40% or more, a sufficient amount of intrapore discharge can be generated for image formation. Further, when the porosity is 95% or less, the energy received per place at the time of discharge is reduced, so that the decrease in stain resistance is suppressed and the black spot image is less likely to occur. The porosity is more preferably 50% or more and 90% or less, and further preferably 60% or more and 85% or less.

The porosity can be confirmed as follows. It can be measured by cutting out a section including the intermediate layer and the surface layer from the conductive member and performing X-ray CT measurement. The porosity measurement point is arbitrary, but in order to prevent the measurement point from being biased, for example, the longitudinal direction of the conductive member is divided into 10 equal parts, and any 1 in each of the obtained 10 regions is obtained. Examples thereof include a method in which points (10 points in total) are used as measurement points. In this case, the average value of the obtained values can be used as the porosity.

<Separation member>
The conductive member may have a separating member. The separating member is not limited as long as the photosensitive drum and the surface layer can be separated from each other and the effect of the present invention is not impaired, and examples thereof include a ring and a spacer. Examples of the method of introducing the separating member include the following methods. When the conductive member has a roller shape, a ring having a larger outer diameter than the conductive member and having a hardness capable of holding a gap between the photosensitive drum and the conductive member has the same center of rotation between the ring and the conductive member. How to arrange so that it is in position. When the conductive member has a blade shape, a method of introducing a spacer that can separate the conductive member and the photosensitive drum so that they do not rub or wear.

The material constituting the separating member is not limited as long as it does not interfere with the effect of the present invention, but a known non-conductive material may be appropriately used in order to prevent energization through the separating member. Examples thereof include polymer materials having excellent slidability such as polyacetal resin, high molecular weight polyethylene resin and nylon resin, and metal oxide materials such as titanium oxide and aluminum oxide. These may be used alone or in combination of two or more.

The position where the separating member is introduced is not limited as long as the effect of the present invention is not impaired, and may be installed, for example, at the end portion in the longitudinal direction of the conductive support. FIG. 5 shows an example (roller shape) of the conductive member when the separating member is introduced. In FIG. 5, 50 is a conductive member, 51 is a separating member, and 52 is a conductive support (conductive shaft core).

[Process cartridge]
The process cartridge according to one aspect of the present invention is a process cartridge that is detachably configured to be attached to and detached from the main body of the electrophotographic apparatus, and includes a conductive member according to one aspect of the present invention. FIG. 6 shows an example of a process cartridge for electrophotographic that includes the conductive member as a charging roller. The process cartridge shown in FIG. 6 integrates a developing device and a charging device, and is configured to be removable from the main body of the electrophotographic apparatus. The developing apparatus integrates at least the developing roller 63 and the toner container 66, and may include a toner supply roller 64, a toner 69, a developing blade 68, and a stirring blade 610, if necessary. The charging device is at least integrated with the photosensitive drum 61, the cleaning blade 65, and the charging roller 62, and may include a waste toner container 67. A voltage is applied to the charging roller 62, the developing roller 63, the toner supply roller 64, and the developing blade 68, respectively.

[Electrographer]
The electrophotographic apparatus according to one aspect of the present invention includes a conductive member according to one aspect of the present invention. FIG. 7 shows an example of an electrophotographic apparatus including the conductive member as a charging roller. The electrophotographic apparatus shown in FIG. 7 is a color electrophotographic apparatus in which the four process cartridges are detachably attached. Black, magenta, yellow, and cyan toners are used in each process cartridge. The photosensitive drum 71 rotates in the direction of the arrow and is uniformly charged by the charging roller 72 to which a voltage is applied from the charging bias power supply, and an electrostatic latent image is formed on the surface by the exposure light 711. On the other hand, the toner 79 stored in the toner container 76 is supplied to the toner supply roller 74 by the stirring blade 710, and is conveyed from the toner supply roller 74 onto the developing roller 73. Then, the developing blade 78 arranged in contact with the developing roller 73 uniformly coats the toner 79 on the surface of the developing roller 73, and the toner 79 is charged by triboelectric charging. The electrostatic latent image is developed by applying toner 79 conveyed by a developing roller 73 that is arranged in contact with the photosensitive drum 71, and is visualized as a toner image.

The visualized toner image on the photosensitive drum 71 is transferred to the intermediate transfer belt 715 which is supported and driven by the tension roller 713 and the intermediate transfer belt drive roller 714 by the primary transfer roller 712 to which a voltage is applied by the primary transfer bias power supply. Will be done. Toner images of each color are sequentially superimposed, and a color image is formed on the intermediate transfer belt 715. The transfer material 719 is fed into the apparatus by a paper feed roller (not shown), and is conveyed between the intermediate transfer belt 715 and the secondary transfer roller 716. A voltage is applied to the secondary transfer roller 716 from a secondary transfer bias power supply (not shown) to transfer the color image on the intermediate transfer belt 715 to the transfer material 719. The transfer material 719 on which the color image is transferred is fixed by the fixing device 718, and the paper is discharged to the outside of the apparatus to complete the printing operation. On the other hand, the toner 79 remaining on the photosensitive drum 71 without being transferred is scraped off by the cleaning blade 75 and stored in the waste toner storage container 77, and the cleaned photosensitive drum 71 is repeatedly used in the above-mentioned steps. .. Further, the toner 79 remaining on the intermediate transfer belt 715 without being transferred is also scraped off by the cleaning device 717.

<Example 1>
[1. Fabrication of conductive support]
A round bar-shaped free-cutting steel having a total length of 252 mm having a stepwise different outer diameter was prepared as a conductive shaft core. The range of the central portion 230 mm excluding the both end portions 11 mm of the round bar-shaped free-cutting steel has an outer diameter of 8.5 mm, and the portion of the both end portions 11 mm has an outer diameter of 6 mm. The round bar-shaped free-cutting steel was used as the conductive support A1.

[2. Formation of intermediate layer]
Polybutyl methacrylate (PtBMA) (manufactured by Sigma-Aldrich, weight average molecular weight: 170,000) was dissolved in N, N-dimethylacetylamide (DMAC) in an amount of 2% by mass to obtain a coating solution 1. The conductive support A1 was immersed in the coating liquid 1 with its longitudinal direction in the vertical direction, and the coating liquid 1 was coated by a dipping method. The immersion time was 9 seconds. The pulling speed was 20 mm / sec for the initial speed and 3 mm / sec for the final speed, during which the speed was changed linearly with time. The obtained coated product was air-dried at room temperature for 30 minutes and dried in a hot air circulation dryer set at a temperature of 160 ° C. for 15 minutes to obtain a conductive roller A1 having an intermediate layer.

[3. Surface layer formation]
Add 12 g of polyvinyl alcohol (PVA, weight average molecular weight: 155,000, saponification degree: 87 to 89 mol%, manufactured by Sigma Aldrich) and 120 mL of water as a skeleton material to the eggplant flask, and stir and heat to reflux to prepare an aqueous solution. Obtained. The aqueous solution was cooled to 50 ° C., and a mixed solvent of 58 ml of water and 130 ml of acetone was added thereto to prepare a PVA solution. The PVA solution was injected into a mold in which the conductive roller A1 was set, sealed, and allowed to stand at 20 ° C. for 12 hours. The mixture was washed with isopropyl alcohol three times, and the water in the mixed solvent was replaced with isopropyl alcohol. Then, it was dried under reduced pressure at room temperature for 24 hours to remove isopropyl alcohol to produce a conductive member A1 having a surface layer.

[4. Characteristic evaluation]
The obtained conductive member A1 was subjected to the following evaluation test. The evaluation results are shown in Table 5. When the conductive member is a roller-shaped conductive member, the x-axis direction, the y-axis direction, and the z-axis direction mean the following directions, respectively. The x-axis direction is the longitudinal direction of the roller (conductive member). The y-axis direction is a tangential direction in the cross section (that is, the circular cross section) of the roller (conductive member) orthogonal to the x-axis. The z-axis direction is the radial direction in the cross section of the roller (conductive member) orthogonal to the x-axis. Further, the "xy plane" means a plane orthogonal to the z-axis, and the "yz cross section" means a cross section orthogonal to the x-axis.

[Evaluation 4-1. Evaluation of non-conductive nature of the intermediate layer]
The non-conductive property of the intermediate layer was evaluated by the following method. The volume resistivity of the intermediate layer was measured in a contact mode using a scanning probe microscope (SPM) (trade name: Q-Scope250, manufactured by Quant Instrument Corporation).

First, the conductive member A1 was equally divided into 10 regions in the longitudinal direction. Then, a section is cut out from each region by a focused ion beam method to a length of 1 mm in the x-axis direction, a length of 500 μm in the y-axis direction, and a depth of 700 μm including the conductive support A1 in the z-axis direction. A total of 10 test pieces were prepared. Next, each test piece was placed on a stainless steel metal plate so that the portion of the conductive support A1 was in contact with the metal plate, and a measurement section was obtained.

Next, the cantilever of the SPM was brought into contact with the intermediate layer portion of each measurement section, a voltage of 50 V was applied to the cantilever, and the current value was measured. Next, the yz cross section of each test piece was observed, and the thickness of the intermediate layer was measured. Further, the volume resistivity was calculated from the thickness and the current value. The average value of the volume resistivity obtained from each test piece was taken as the volume resistivity of the intermediate layer in this evaluation.

[Evaluation 4-2. Measurement of intermediate layer thickness]
In the above evaluation 4-1 the average value of the thickness of the intermediate layer measured from each test piece was taken as the thickness of the intermediate layer in this evaluation.

[Evaluation 4-3. Confirmation of radiation decay property of the resin forming the intermediate layer]
Whether or not the resin forming the intermediate layer was a radiation decay type resin was confirmed by corona discharge treatment and GPC measurement. Specifically, the intermediate layer was peeled off from the conductive member A1 and the mass of the sample was measured. Then, from toluene, chlorobenzene, tetrahydrofuran (THF), trifluoroacetic acid, and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), a soluble solvent was selected and 1% by mass was selected. Sample solution was prepared. Using the prepared sample solution, the molecular weight was measured under the following conditions. The column was stabilized in a heat chamber at a temperature of 40 ° C., and the solvent used for dissolving the sample was flowed through the column at this temperature as an eluent at a flow rate of 1 mL / min. 100 μL of the sample solution was injected into the column. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of the calibration curve prepared from several types of monodisperse polystyrene standard samples and the retention time. As the monodisperse polystyrene standard sample, TSKgel standard polystyrenes "0005202" to "0005211" (trade name, manufactured by Tosoh Corporation) were used. A GPC gel permeation chromatograph device (trade name: HLC-8120, manufactured by Tosoh Corporation) was used as the GPC device, and a differential refractive index detector (trade name: RI-8020, manufactured by Tosoh Corporation) was used as the detector. As the column, three commercially available polystyrene gel columns (trade name: TSK-GEL SUPER HM-M, manufactured by Tosoh Corporation) were used in combination. The weight average molecular weight (Mw) of the sample sampled from the intermediate layer of the conductive member A1 before the corona discharge treatment was 170,000.

Subsequently, the corona discharge treatment of the conductive member A1 was performed using a corona discharge surface treatment device manufactured by Kasuga Electric Co., Ltd. The implementation environment was an H / H environment (environment with a temperature of 30 ° C. and a relative humidity of 80%). The method of corona discharge treatment is shown in FIG. Both ends 82 of the conductive member 81 are fixed by the support portion 83 so that the longitudinal direction of the aluminum corona electrode 84 is parallel to the longitudinal direction of the conductive member 81, and the surface of the corona electrode 84 is the conductive member. The position was adjusted so as to face the surface of 81. The distance between the surface of the corona electrode 84 and the surface of the conductive member 81 in close contact with each other was set to 1 mm. The conductive member 81 was rotated by rotating the support portion 83 at a speed of 30 rotations per minute, and the state in which 8 KV was applied from the power source 85 to the electrode side was continued for 2 hours.

Then, the intermediate layer was peeled off from the conductive member A1 after the corona discharge treatment to measure the mass, and then Mw was measured by GPC by the same method as described above. When the Mw of the sample after the corona discharge treatment is equal to or less than the Mw of the sample before the corona discharge treatment, it is determined that the resin is a radiation decay type resin. On the other hand, when Mw increased after the corona discharge treatment, it was determined that the resin was a radiation crosslinked type. The Mw of the sample before the corona discharge treatment of the conductive member A1 is 170,000, the Mw of the sample after the corona discharge treatment is 168,000, and the resin forming the intermediate layer of the conductive member A1 is radiation-disintegrated. It was a mold. In Table 5 described later, which shows the evaluation results, the "radiation-disintegrating type resin" was described as "disintegrating type", and the "radiation-crosslinked type resin" was described as "crosslinked type".

[Evaluation 4-4. Measurement of glass transition temperature (Tg)]
First, the intermediate layer of the conductive member A1 was peeled off with tweezers to obtain a 3 mg sample. The differential scanning calorimetry was performed on the sample using a differential scanning calorimetry device (trade name: DSC7020AS, manufactured by Yamato Scientific Co., Ltd.). After allowing to stand at a temperature of −150 ° C. for 30 minutes, the inflow and outflow of heat energy was measured while changing the temperature to 250 ° C. at a heating rate of 10 ° C./min. The measurement data was analyzed by the analysis software attached to the device to obtain the glass transition temperature Tg.

[Evaluation 4-5. Confirmation of the co-continuous structure of the porous body of the surface layer]
The co-continuous structure of the porous body of the surface layer was evaluated by the following method. A razor is applied to the surface layer of the conductive member A1 to have a length of 250 μm in the x-axis direction and the y-axis direction, and any intermediate layer is included in the z-axis direction so as to include the entire surface layer. Sections were cut out at depth. Next, a three-dimensional reconstruction was performed on the section using an X-ray CT inspection device (trade name: TX-300, manufactured by Token Co., Ltd.). From the obtained three-dimensional image, a two-dimensional slice image (parallel to the xy plane) was cut out at an interval of 1 μm with respect to the z-axis. Next, these slice images were binarized to distinguish between the skeleton and the pores. The slice images were sequentially confirmed with respect to the z-axis, and it was confirmed whether or not the skeleton portion and the pore portion were three-dimensionally continuous. From this, the presence or absence of the co-continuous structure was judged.

[Evaluation 4-6. Evaluation of surface layer fineness]
The fineness of the surface layer was evaluated as follows. The surface of the section used in the evaluation 4-5 was platinum-deposited to obtain a vapor-deposited section. Next, the surface of the vapor-deposited section was photographed from the z-axis direction using a scanning electron microscope (SEM) (trade name: S-4800, manufactured by Hitachi High-Technologies Corporation) at a magnification of 1000 to obtain a surface image. .. Using image processing software (trade name: Imageplus, manufactured by Media Cybernetics), the surface image is grayscaled and binarized in a 150 μm square area, and edge extraction is performed to create a boundary line between the skeleton and the pores. Extraction was performed to obtain a borderline image. At this time, the background was white and the boundary line was black. Next, 14 black grid lines of 2.5 μm square were prepared vertically and 14 horizontally on a white background to form a grid image having a total of 225 white cells. The boundary line image and the grid image were superposed to obtain an evaluation image. In the evaluation image, the square group consisting only of the skeleton and the square group consisting only of the pores do not include a boundary line in the region of 2.5 μm square. Therefore, in the evaluation image, the ratio of the number of cells having the same area as the 2.5 μm grid was calculated by the counting function of Imageplus. The evaluation was performed according to the following criteria.

Rank A: The total number of square groups consisting only of the skeleton and the number of square groups consisting only of the pores is 5% or less of the total number of square groups.
Rank B: The total number of square groups consisting only of the skeleton and the number of square groups consisting only of the pores exceeds 5% of the total number of square groups and is 15% or less.
Rank C: The total number of square groups consisting only of the skeleton and the number of square groups consisting only of the pores exceeds 15% of the total number of square groups and is 25% or less.
Rank D: The total number of square groups consisting only of the skeleton and the number of square groups consisting only of the pores exceeds 25% of the total number of square groups.

[Evaluation 4-7. Evaluation of cross-sectional shape (circularity K) of pores in the surface layer]
The cross-sectional shape of the pores of the surface layer was evaluated as follows. In the binarized image obtained by binarizing the two-dimensional slice image obtained by the X-ray CT measurement of the evaluation 4-5, the perimeter of each pore is L and the area of the pore is S. , Circularity K = L ² / 4πS was calculated. The conductive member A1 is divided into 10 regions in the longitudinal direction into 10 equal parts, and the binarized image is acquired from a total of 10 points, one point arbitrarily from each region, and the circularity K is calculated. The average value was defined as circularity K.

[Evaluation 4-8. Evaluation of surface layer thickness]
The thickness of the surface layer was evaluated as follows. The two-dimensional slice image obtained by the measurement of the X-ray CT of the evaluation 4-5 was binarized, and the porous portion and the vacant portion were distinguished. In each of the binarized slice images, the ratio occupied by the porous part was quantified, the numerical value was confirmed from the conductive support to the surface layer side, and the point where the ratio was 2% or less was the outermost surface of the surface layer. It was a department. Thereby, the thickness of the surface layer was measured. This work was performed on any one point (10 points in total) in each region obtained by dividing the conductive member A1 into 10 equal parts in the longitudinal direction, and the obtained values were averaged to obtain the surface layer thickness. ..

[Evaluation 4-9. Evaluation of surface layer porosity]
In the three-dimensional image obtained by the evaluation of the X-ray CT of the evaluation 4-5, the proportion occupied by the pores was quantified, and the porosity of the surface layer was determined. This work is performed on any one point (10 points in total) in each region obtained by dividing the conductive member A1 into 10 equal parts in the longitudinal direction, and the average value of the obtained values is the porosity of the surface layer. And said.

[Evaluation 4-10. Evaluation of non-conductiveness of surface layer]
The non-conductive property of the surface layer was evaluated by the following method. The volume resistivity of the surface layer was measured in a contact mode using a scanning probe microscope (SPM) (trade name: Q-Scope250, manufactured by Quant Instrument Corporation).
First, the conductive member A1 was equally divided into 10 regions in the longitudinal direction. Then, the surface layer in each region was collected with tweezers, and 10 samples were prepared. Each of the samples was placed on a stainless steel metal plate to prepare 10 measurement sections. Next, for each measurement section, the cantilever of SPM was brought into contact with the sample on the metal plate, a voltage of 50 V was applied to the cantilever, and the current value was measured.
Further, with the SPM, the thickness of the sample at the portion where the current value was measured was measured. The current value was converted into volume resistivity from the measured thickness and the contact area of the cantilever. The average value of the volume resistivity obtained from each measurement section was taken as the volume resistivity of the surface layer in this evaluation.

[Evaluation 4-11. Confirmation of radiation decay property of the resin forming the surface layer and evaluation of Tg]
The radiation disintegration property of the resin forming the surface layer is the same as the method of evaluation (evaluation 4-3, evaluation 4-4) in the intermediate layer except that the surface layer is peeled from the conductive member A1 to form a test piece. And the glass transition temperature Tg was evaluated.

[5. Durability evaluation]
[Evaluation 5-1. Durability evaluation A]
(Evaluation 5-1-1. Evaluation of accumulated charge amount of new conductive member)
The surface potential (accumulated charge amount) of the new conductive member A1 was measured as follows. First, as an electrophotographic apparatus, an electrophotographic laser printer (trade name: Laserjet CP4525dn, manufactured by HP) was prepared. However, in order to put the conductive member in a harsher evaluation environment, the laser printer was changed so that the number of output sheets per unit time was 50 sheets / minute on A4 size paper, which is larger than the original number of output sheets. bottom. At that time, the output speed of the recording medium was set to 300 mm / sec, and the image resolution was set to 1,200 dpi. A conductive member A1 was attached as a charging roller to a toner cartridge dedicated to a laser printer. Further, a surface potential probe (trade name: Model 555P-1 manufactured by Trek Japan) connected to a surface electrometer (trade name: Model 347 Trek Japan) can be placed in the cartridge of the above electrograph so that the accumulated charge amount can be measured. Fixed to. Specifically, the surface potential probe was fixed to the surface of the conductive member A1 with a polyimide tape so as to face the surface at a distance of 1 mm. This toner cartridge was loaded into the laser printer.

Then, using the laser printer, a solid white image was formed in an H / H environment (environment with a temperature of 30 ° C. and a relative humidity of 80%). The voltage applied between the conductive member A1 which is a charging roller and the photosensitive drum was set to -1,200 V. Then, the surface potential of the conductive member A1 during the output of the solid white image was measured. The difference between the surface potential measured at this time and the voltage applied between the charging roller and the photosensitive drum was taken as the accumulated charge amount of the new conductive member A1.

In order to confirm the effect of suppressing the decrease in chargeability after long-term use, the above-mentioned accumulated charge amount was measured before and after each of the durability tests A and B described later. At this time, the applied voltage between the charging roller and the photosensitive drum was measured at the applied voltage during the durability test. In addition, the rate of decrease in the amount of accumulated charge before and after the durability test was calculated.

(Evaluation 5-1-2. Evaluation of image defects due to adhesion of dirt on the surface Black spot)
Using the laser printer used in Evaluation 5-1-1, 100,000 electrophotographic images were output in an H / H environment (environment with a temperature of 30 ° C. and a relative humidity of 80%). The output was performed by an intermittent image forming operation in which the rotation of the photosensitive drum was completely stopped for about 3 seconds after the two images were output, and the image output was restarted. Further, the output image was an image in which the letter "E" of the alphabet having a size of 4 points was printed so that the coverage was 4% with respect to the area of A4 size paper. Further, in forming the electrophotographic image, the applied voltage between the conductive member A1 which is a charging roller and the photosensitive drum was set to -1,200 V.

After outputting 100,000 electrophotographic images, one halftone image (an image in which a horizontal line having a width of 1 dot and an interval of 2 dots is drawn in the direction perpendicular to the rotation direction of the photosensitive drum) was output. The voltage applied between the charging roller and the photosensitive drum at this time was also set to -1,200 V. The obtained halftone image was visually observed, and the presence or absence of image defects due to dirt on the surface of the charging roller and the degree of image defects were evaluated according to the following criteria.

Rank A: There are no image defects due to dirt adhesion.
Rank B: Image defects (black spots) due to slight stains are observed in some parts.
Rank C: Image defects (black spots) due to slight stains are observed on the entire surface.
Rank D: Image defects (black spots) due to dirt adhesion are observed on the entire surface, and image defects are observed as vertical streaks.

(Evaluation 5-1-3. Evaluation of accumulated charge of conductive member after long-term use)
The amount of accumulated charge of the conductive member A1 used in the above evaluation 5-1-2 was measured in the same manner as in the above evaluation 5-1-1.

[Evaluation 5-2. Durability evaluation B]
When the evaluation result according to the evaluation 5-1-2 was rank A or rank B, this durability evaluation B was performed.

(Evaluation 5-2-1. Evaluation of accumulated charge amount of new conductive member)
The amount of accumulated charge was measured in the same manner as in the above evaluation 5-1-1 except that the applied voltage between the conductive member A1 which is a charging roller and the photosensitive drum was set to -1,500 V.

(Evaluation 5-2-2. Evaluation of image defects due to adhesion of dirt on the surface Black spot)
As the durability test B, evaluation 5-1 except that the applied voltage between the conductive member A1 and the photosensitive drum at the time of outputting 100,000 electrophotographic images and at the time of outputting halftone images was set to -1,500 V. It was evaluated in the same manner as -2.

(Evaluation 5-2-3. Evaluation of accumulated charge of conductive member after long-term use)
The amount of accumulated charge of the conductive member A1 used in the evaluation 5-2-1 was measured in the same manner as in the evaluation 5-2-1.

<Examples 2 to 17>
Conductive members A2 to A17 were produced in the same manner as in Example 1 except that the coating liquids 2 to 17 shown in Table 1 were used for forming the intermediate layer.

PtBMA: Tershally Butyl Polymethacrylate (R ₁ : -C (CH ₃ ) ₃ )
PEMA: Polyethyl methacrylate (R ₁ : -CH ₂ CH ₃ )
PBMA: Butyl polymethacrylate (R ₁ : -CH ₂ CH ₂ CH ₂ CH ₃ )
PiBMA: Isobutyl polymethacrylate (R ₁ : -CH ₂ CH (CH ₃ ) ₂ )
PiPMA: Polyisopropyl methacrylate (R ₁ : -CH (CH ₃ ) ₂ )
P (B-iB) MA: Butyl methacrylate-isobutyl methacrylate copolymer P (BE) MA: Butyl methacrylate-ethyl methacrylate copolymer PCMA _{: Polycyclohexyl methacrylate (R 1} : -Cy)
PMS: Poly-α-methylstyrene POM: Polyacetal PIB: Polyisobutylene PS: Polystyrene DMAC: N, N-Dimethylacetamide HFIP: 1,1,1,3,3,3-hexafluoro-2-propanol.

<Example 18>
Each material of the type and amount shown in Table 2 was mixed with a pressure kneader to obtain an A kneaded rubber composition. Further, 166 parts by mass of the A kneaded rubber composition and each material of the type and amount shown in Table 3 were mixed by an open roll to prepare a B kneaded rubber composition.

A round bar having a total length of 252 mm and an outer diameter of 6 mm was prepared by subjecting the surface of the free-cutting steel to electroless nickel plating. Next, the adhesive was applied over the entire circumference in a range of 230 mm excluding 11 mm at both ends of the round bar. A conductive hot melt type adhesive was used as the adhesive. A roll coater was used for coating. A round bar coated with the adhesive was used as a conductive shaft core. A conductive resin layer was provided on the surface of the conductive shaft core. Prepare a crosshead extruder that has a supply mechanism for the conductive shaft core and a discharge mechanism for unvulcanized rubber rollers, attach a die with an inner diameter of 12.5 mm to the crosshead, and heat the extruder and crosshead to 80 ° C. The transport speed of the shaft core was adjusted to 60 mm / sec. Under these conditions, the B kneaded rubber composition is supplied from the extruder, a layer of the B kneaded rubber composition is formed on the outer peripheral surface of the conductive shaft core in the crosshead, and an unvulcanized rubber roller is formed. Obtained. Next, the unvulcanized rubber roller was put into a hot air vulcanization furnace at 170 ° C. and heated for 60 minutes to vulcanize the unvulcanized NBR in the layer of the B kneaded rubber composition, resulting in unpolished conductivity. Got a roller. Then, the end portion of the conductive resin layer was excised. Finally, the surface of the conductive resin layer was polished with a rotary grindstone. As a result, a conductive roller having a diameter of 8.4 mm and a diameter of the central portion of 8.5 mm was obtained at a position of 90 mm from the central portion to both end portions. The conductive member A18 was manufactured in the same manner as in Example 1 except that the conductive roller was used.

<Example 19>
The materials shown in Table 4 were mixed with an open roll to prepare an unvulcanized rubber composition. A conductive roller was obtained in the same manner as in Example 18 except that the B kneaded rubber composition in Example 18 was changed to the unvulcanized rubber composition. The conductive member A19 was manufactured in the same manner as in Example 1 except that the conductive roller was used.

<Example 20>
The conductive member A20 was manufactured in the same manner as in Example 1 except that the conductive support made of aluminum was used as the conductive support.

<Example 21>
12 g of polyvinylidene fluoride (PVDF) (weight average molecular weight: 530,000, manufactured by Sigma-Aldrich) as a skeleton material and 200 mL of DMAC were added to a eggplant flask, and the mixture was stirred and heated to reflux to obtain a solution. A mixed solvent of 55 ml of DMAC and 45 ml of ethylene glycol was added thereto to prepare a PVDF solution. The PVDF solution was injected into the mold in which the conductive roller A1 of Example 1 was set, sealed, and allowed to stand at 20 ° C. for 12 hours. It was washed with isopropyl alcohol three times, and then dried under reduced pressure at room temperature for 24 hours to remove isopropyl alcohol to produce the conductive member A21.

<Example 22>
15 g of polystyrene (PS) (weight average molecular weight: 262,000, manufactured by Sigma-Aldrich) as a skeleton material and 200 mL of chloroform were added to an eggplant flask, and the mixture was stirred and heated to reflux to obtain a solution. A mixed solvent of 40 ml of chloroform and 60 ml of cyclohexane was added thereto to prepare a PS solution. The PS solution was injected into the mold in which the conductive roller A1 of Example 1 was set, sealed, and allowed to stand at 20 ° C. for 12 hours. The conductive member A22 was manufactured by washing and drying.

<Example 23>
Add 6 g of cellulose acetate (trade name: L-70, manufactured by Daicel Co., Ltd., vinegaring degree: 55%) as a skeleton material, 250 g of acetone as a solvent, and 47 g of 1-octanol to a eggplant flask, and stir to add cellulose acetate. It was dissolved to prepare a cellulose acetate solution. The cellulose acetate solution was dipped once on the conductive roller A1 of Example 1, air-dried at 23 ° C. for 30 minutes or more, and then dried in a hot air circulation dryer set at 140 ° C. for 1 hour to obtain a conductive member. A23 was manufactured.

<Example 24>
12 g of polyacrylonitrile (PAN) (weight average molecular weight: 150,000, manufactured by Sigma-Aldrich) as a skeleton material, 255 g of dimethyl sulfoxide as a solvent, and 40 g of water were added to a eggplant flask and stirred to prepare a PAN solution. The PAN solution was dipped once on the conductive roller A1 of Example 1 and air-dried at 25 ° C. for 12 minutes or more to produce a conductive member A24.

<Example 25>
A chitosan solution was prepared by adding 2 g of chitosan (manufactured by Sigma-Aldrich) as a skeleton material, 100 g of a 1 mol / L acetic acid aqueous solution as a solvent, and 0.2 g of ethylene glycol. The chitosan solution was injected into the mold in which the conductive roller A1 of Example 1 was set, sealed, and allowed to stand at −6 ° C. for 6 hours and at −30 ° C. for 6 hours. Then, after cooling at −80 ° C. for 6 hours under reduced pressure, it was immersed in a 2 mol / L sodium hydroxide aqueous solution for 24 hours and washed with water to produce a conductive member A25.

<Example 26>
A PtBMA solution was prepared by adding 12 g of PtBMA (manufactured by Sigma-Aldrich, Inc., weight average molecular weight: 17,000,000) as a skeleton material, 200 g of DMAC as a solvent, and 40 g of water. The PtBMA solution was dipped once on the conductive roller A1 of Example 1, air-dried at 25 ° C. for 30 minutes or more, and then dried in a hot air circulation dryer set at 60 ° C. for 1 hour to obtain the conductive member A26. Was produced. The conductive member A26 was evaluated in the same manner as in Example 1.

<Example 27>
16 g of polymethyl methacrylate (PMMA) (manufactured by Sigma-Aldrich, weight average molecular weight: 99,600) as a skeleton material, 55 ml of distilled water as a solvent, and 230 ml of ethanol were added to the eggplant flask. This was heated under reflux with stirring to dissolve PMMA to prepare a PMMA solution. The PMMA solution was dipped once on the conductive roller A1 of Example 1, air-dried at 23 ° C. for 30 minutes or more, and then dried in a hot air circulation dryer set at 60 ° C. for 1 hour to obtain the conductive member A27. Made. The conductive member A27 was evaluated in the same manner as in Example 1.

<Example 28>
A PiBMA solution was prepared by adding 8 g of PiBMA (manufactured by Sigma-Aldrich, Inc., weight average molecular weight: 301,000) as a skeleton material, 220 g of DMAC as a solvent, and 40 g of water. The PiBMA solution was dipped once on the conductive roller A1 of Example 1, air-dried at 25 ° C. for 30 minutes or more, and then dried in a hot air circulation dryer set at 30 ° C. for 2 hours to obtain the conductive member A28. Made.

<Example 29>
A PCMA solution was prepared by adding 18 g of PCMA (manufactured by Sigma-Aldrich, Inc., weight average molecular weight: 65,000) as a skeleton material, 240 g of DMAC as a solvent, and 40 g of water. The PCMA solution was dipped once on the conductive roller A1 of Example 1, air-dried at 25 ° C. for 30 minutes or more, and then dried in a hot air circulation dryer set at 60 ° C. for 2 hours to obtain the conductive member A29. Made.

<Examples 30 to 34>
Conductive members A30 to A34 were prepared by providing a surface layer on the conductive roller A15 provided with the intermediate layer of cellulose acetate prepared in Example 15 in the same manner as in Examples 24 to 26, 28 and 29.

<Example 35>
22 g of PVA (weight average molecular weight: 50,000, saponification degree: 98 to 99 mol%, manufactured by Sigma Aldrich) as a skeleton material and 140 mL of water were added to a eggplant flask, and the mixture was stirred and heated to reflux to obtain an aqueous solution. The aqueous solution was cooled to 50 ° C., and a mixed solvent of 45 ml of water and 100 ml of acetone was added thereto to prepare a PVA solution. A conductive member A35 was produced in the same manner as in Example 1 except that the surface layer was formed using the PVA solution. After forming the surface layer, heat treatment was performed at a humidity of 50% and 70 ° C. for 10 minutes, and the surface was uniformly prepared by polishing to obtain a conductive member A35.

<Example 36>
The conductive member A36 was produced in the same manner as in Example 35 except that the heat treatment was carried out at a humidity of 50% and 70 ° C. for 1 hour.

<Example 37>
The PVA powder used as the skeleton material in the formation of the surface layer of Example 1 was freeze-ground using a freezing crusher (trade name: JFC-2000, manufactured by Nippon Analytical Industry Co., Ltd.). Specifically, 10 g of PVA powder was put into a stainless steel sample container of the refrigerating crusher together with a tungsten carbide steel ball. After mounting this container on the crushing rod, the crushing rod was mounted on the main body of the freezing crusher. Then, the whole sample container was immersed in liquid nitrogen and cooled for 5 minutes, and then the crushing rod was reciprocated at 1000 times / minute for 10 minutes to crush the PVA powder in the sample container. Then, the sample container was returned to room temperature A (23 ° C.), and then the fine powder of PVA was taken out from the sample container.

Next, the obtained fine powder of PVA was classified using a wind power classifier. Specifically, a wind power classifier (trade name: Elbow Jet Lab EJ-L3, manufactured by Nittetsu Mining Co., Ltd.) was used. Fine powder of PVA was put into the wind power classifier, and the true specific density and the desired particle size were input on the operation screen to perform the classifying process. Then, a PVA fine powder having a particle size of 0.5 μm or more and 8 μm or less was obtained. The PVA fine powder was put into a mold in which the conductive roller A1 of Example 1 was set, and heat-treated at a humidity of 50% and 80 ° C. for 1 hour. The surface was uniformly prepared by polishing to prepare a conductive member A37.

<Examples 38-40>
Same as coating liquid 1 except that 7 parts by mass, 5 parts by mass, or 2 parts by mass of carbon black (CB, manufactured by Asahi Carbon, trade name: X15) was added to 100 parts by mass of PtBMA. Then, the coating liquid 1 (2) to the coating liquid 1 (4) were prepared. Conductive members A38 to A40 were produced in the same manner as in Example 1 except that these coating liquids were used for forming the intermediate layer.

<Example 41>
Coating liquid 1 (5) was prepared in the same manner as coating liquid 1 except that 5 parts by mass of p-hydroquinone (manufactured by Sigma-Aldrich) was added to 100 parts by mass of PtBMA. The conductive member A41 was manufactured in the same manner as in Example 1 except that the coating liquid 1 (5) was used for forming the intermediate layer.

<Example 42>
The PtBMA powder used in the preparation of the coating liquid 1 of Example 1 was freeze-pulverized and classified in the same manner as in Example 37 to obtain a PtBMA fine powder having a particle size of 0.5 μm or more and 8 μm or less. The obtained PtBMA fine powder having a particle size of 0.5 μm or more and 8 μm or less was put into a mold in which the conductive support A1 was set, and heat-treated at 120 ° C. for 1 hour. The surface was uniformly prepared by polishing to prepare a conductive roller A42 having a porous intermediate layer. The conductive member A42 was manufactured in the same manner as in Example 1 except that the conductive roller A42 was used.

<Example 43>
A ring having an outer diameter of 8.6 mm, an inner diameter of 6 mm, and a width of 2 mm was attached to the ends of the intermediate layer and the surface layer of the conductive member A1 of Example 1 as a separating member to manufacture the conductive member A43.

The conductive members A2 to A43 according to Examples 2 to 43 were subjected to the evaluations 4-1 to 4-10 and evaluations 5-1 to 5-3 described in Example 1. The evaluation results of the conductive members A1 to A43 are shown in Tables 5 to 9.

<Comparative example 1>
The conductive member C1 was manufactured in the same manner as in Example 1 except that the intermediate layer was not formed.

<Comparative example 2>
In the formation of the intermediate layer, the conductive member C2 was produced in the same manner as in Example 1 except that the coating liquid 18 shown in Table 1 was used instead of the coating liquid 1.

<Comparative example 3>
Compared to 100 parts by mass of PtBMA used in the preparation of coating liquid 1, 12 parts by mass of carbon black (CB, manufactured by Asahi Carbon, trade name: X15) was added in the same manner as in coating liquid 1. An example coating liquid C1 was prepared. The conductive member C3 was produced in the same manner as in Example 1 except that the intermediate layer was formed by using the coating liquid C1.

<Comparative example 4>
In forming the surface layer, a solution obtained by adding 7.5 parts by mass of carbon black (CB, manufactured by Asahi Carbon, trade name: X15) to 100 parts by mass of PVA to the PVA solution used in Example 1 was used. Other than that, the conductive member C4 was manufactured in the same manner as in Example 1.

<Comparative example 5>
After forming the surface layer in the same manner as in Example 6, heat treatment was performed at a humidity of 50% and 80 ° C. for 1 hour. The surface was made uniform and the surface was polished to adjust the thickness to obtain a conductive member C5.

<Comparative Example 6>
The conductive member C6 was produced in the same manner as in Example 35, except that the heat treatment was carried out at a humidity of 50% and 80 ° C. for 1 hour.

The conductive members C1 to C6 according to Comparative Examples 1 to 6 were subjected to evaluations 4-1 to 4-10 and evaluations 5-1 to 5-3 described in Example 1. The results are shown in Table 10.

Since the conductive member C1 according to Comparative Example 1 does not have an intermediate layer, the amount of accumulated charges after the durability test is significantly reduced, and the image evaluation is poor.
In the conductive member C2 according to Comparative Example 2, since the intermediate layer did not contain the radiation-disintegrating resin, the amount of accumulated charge after the durability test was significantly reduced, and the image evaluation was poor.
Since the intermediate layer of the conductive member C3 according to Comparative Example 3 is conductive, the amount of accumulated charge after the durability test is significantly reduced, and the image evaluation is poor.
Since the surface layer of the conductive member C4 according to Comparative Example 4 is conductive, a sufficient amount of accumulated charges could not be obtained, and the image evaluation was poor.
Since the surface layer of the conductive member C5 according to Comparative Example 5 does not have a co-continuous structure, a sufficient amount of accumulated charge cannot be obtained, the rate of decrease of the amount of accumulated charge after the durability test is large, and the image evaluation is poor. Met.
In the conductive member C6 according to Comparative Example 6, since the skeleton of the surface layer is large (not fine), a sufficient amount of accumulated charge cannot be obtained, the rate of decrease in the amount of accumulated charge after the durability test is large, and the image evaluation is poor. Met.

31 Surface layer 32 Conductive support (conductive shaft core)
33 Middle class

Claims (16)

An electrophotographic conductive member having a conductive support, an intermediate layer on the conductive support, and a surface layer on the intermediate layer.
The intermediate layer is non-conductive and contains a radiation decay type resin A.
The surface layer is a porous body, and is characterized by satisfying the following conditions (1), (2) and (3):
(1) The porous body has a co-continuous structure including a three-dimensionally continuous skeleton and three-dimensionally continuous pores;
(2) When an arbitrary 150 μm square region on the surface of the surface layer is photographed and the region is divided vertically into 15 equal parts and horizontally into 15 equal parts, the number of square groups consisting only of the skeleton and the fineness thereof. The sum with the number of squares consisting only of holes is 25% or less of the total number of squares;
(3) The surface layer is non-conductive. The conductive member for electrophotographic according to claim 1, wherein the volume resistivity of the intermediate layer is 1 × 10 ¹² Ω · cm or more and 1 × 10 ^{17 Ω · cm or less.} The conductive member for electrophotographic according to claim 1, wherein the volume resistivity of the intermediate layer is 1 × 10 ¹⁵ Ω · cm or more and 1 × 10 ^{17 Ω · cm or less.} The conductive member for electrophotographic according to any one of claims 1 to 3, wherein the radiation-disintegrating resin A is an acrylic resin having a structural unit represented by the following formula (1).

(In the formula (1), R ₁ represents a hydrocarbon group having 1 to 6 carbon atoms). The conductive member for electrophotographic according to claim 4, wherein R ₁ is a linear or branched alkyl group having 2 or more and 6 or less carbon atoms. The electrophotographic conductive member according to claim 4 or 5, wherein R ₁ is at least one selected from the group consisting of the groups represented by the following formulas (2) to (5).
(2) -C (CH ₃ ) ₃ , (3) -CH (CH ₃ ) ₂ , (4) -CH (CH ₃ ) -C (CH ₃ ) ₃ , (5) -C (CH ₃ ) _2- CH (CH ₃ ) ₂ . The conductive member for electrophotographic according to any one of claims 4 to 6, wherein R ₁ is −C (CH ₃ ) _3. The conductive member for electrophotographic according to any one of claims 1 to 7, wherein the thickness of the intermediate layer is 1 μm or more and 5 μm or less. The conductive member for electrophotographic according to any one of claims 1 to 8, wherein the surface layer contains a radiation-disintegrating resin B. The conductive member for electrophotographic according to claim 9, wherein the radiation-disintegrating resin B is an acrylic resin having a structural unit represented by the following formula (6).

(In formula (6), R ₆ represents a hydrocarbon group having 1 to 6 carbon atoms.) The conductive member for electrophotographic according to claim 10, wherein R ₆ is a linear or branched alkyl group having 2 or more and 6 or less carbon atoms. The electrophotographic conductive member according to claim 10 or 11, wherein R ₆ is −C (CH ₃ ) _3. When a cross-sectional image of the surface layer is taken and the peripheral length of the pores in the cross-sectional image is L and the area of the pores is S, the arithmetic mean of the circularity K obtained by ^{L 2 / 4πS is 2 or more.} The conductive member for electrophotographic according to any one of claims 1 to 12. The method for manufacturing a conductive member for electrophotographic according to any one of claims 1 to 13.
A method for producing a conductive member for electrophotographic, which comprises a step of forming the porous body of the surface layer by phase separation of a polymer material and a solvent. A process cartridge that is detachably configured on the main body of an electrophotographic apparatus and includes the conductive member according to any one of claims 1 to 13. An electrophotographic apparatus comprising the conductive member according to any one of claims 1 to 13.

Images