JP2010122608A - Developing roller and method of manufacturing the same, process cartridge for electrophotography, and image forming apparatus for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller capable of forming a stable image by achieving both improvement of adhering property of a resin layer and suppression of deterioration in fogging by use for a long period of time. <P>SOLUTION: The developing roller has a core body, an elastic layer formed of silicone rubber that is provided around the core body and a resin layer covering the elastic layer, and portions which are formed by SiO<SB>2</SB>are scattered between the elastic layer and the resin layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing roller used in an electrophotographic image forming apparatus and a method for manufacturing the developing roller. The present invention further relates to an electrophotographic process cartridge including the developing roller and an electrophotographic image forming apparatus.

  A developing roller used in an electrophotographic image forming apparatus is required to have performance such as suppression of toner deterioration, prevention of permanent deformation, and chargeability to toner in order to obtain a high-quality image. In order to satisfy these requirements, a configuration having an elastic layer and a resin layer coated around the elastic layer is often adopted. Examples of a material suitably used for the elastic layer include silicone rubber having high elasticity. However, since silicone rubber has low reactivity, there are cases where sufficient adhesion to the resin layer cannot be obtained.

In order to solve the above problems, it is conceivable to provide an intermediate layer between the elastic layer and the resin layer. Patent Document 1 discloses a semiconductive roller in which the adhesion between the elastic layer and the resin layer is improved by forming a surface resistance adjusting layer after uniformly forming the SiO ₂ layer on the surface of the semiconductive elastic body. The manufacturing method of this is proposed.
JP 2006-337622 A

However, although the semiconductive roller according to Patent Document 1 can improve the adhesion, a high resistance SiO ₂ layer is uniformly formed on the intermediate layer, so that charges are easily accumulated in the SiO ₂ layer. When this is used as a developing roller, a new problem is caused that charge-up is likely to occur. When the charge-up occurs, the image density may be uneven, or the “fogging” image effect that a developer is developed on a solid white image may occur.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a developing roller that achieves both improvement in adhesion and suppression of charge-up and enables stable image formation over a long period of time.

In order to achieve the above object, the present invention has a shaft core body, an elastic layer formed of silicone rubber provided around the shaft core body, and a resin layer covering the elastic layer. The present invention relates to a developing roller, characterized in that portions formed of SiO ₂ are interspersed between the elastic layer and the resin layer.

After forming the elastic layer, a corona treatment is performed with a corona electrode facing the elastic layer in the longitudinal direction to form a layer mainly composed of SiO ₂ on the surface of the elastic layer, and then at least one layer of resin The method for producing a developing roller according to claim 1, wherein a distance between the corona electrode and the elastic layer is 1 mm or more and 10 mm or less, and an average current density I of the entire corona electrode during corona treatment is formed. The present invention relates to a method for producing a developing roller, wherein (A / m) is 7.0 (A / m) or more and 35.0 (A / m) or less.

  The present invention further includes an electrophotographic image forming apparatus that includes at least a photoconductor for forming an electrostatic latent image and a developing roller that is in contact with the photoconductor, and is detachable from an electrophotographic image forming apparatus. In a photographic process cartridge, the present invention relates to an electrophotographic process cartridge provided with the developing roller.

  Furthermore, the present invention provides an electrophotographic image forming apparatus comprising at least a photosensitive member for forming an electrostatic latent image and a developing roller disposed in contact with the photosensitive member. The present invention relates to an electrophotographic image forming apparatus.

  According to the present invention, it is possible to provide a developing roller that can improve the adhesion between the elastic layer and the resin layer and suppress charge-up, and can stably form an image over a long period of time.

  In addition, according to the present invention, it is possible to provide an electrophotographic process cartridge and an electrophotographic image forming apparatus capable of forming an image stably over a long period of time.

  The present invention relates to a developing roller having a shaft core body, an elastic layer formed of silicone rubber provided around the shaft core body, and a resin layer covering the elastic layer. Applied. The resin layer need not be a single layer, and may be formed in two or more layers.

An example of the developing roller according to the present invention is shown in the schematic view of FIG. (A) in the drawing represents a cross section parallel to the longitudinal direction of the developing roller, and (b) represents a cross section perpendicular to the longitudinal direction. In FIG. 1, a developing roller 10 includes an elastic layer 12 around a cylindrical shaft core 11, a portion formed of SiO ₂ around the elastic layer 12 (hereinafter also referred to as SiO ₂ portion) 13, and the periphery thereof. The resin layer 14 is formed as a coating layer.

Further, details of the SiO ₂ portion 13 are shown in the schematic view of FIG. (A) in the figure is an enlarged view of a cross section parallel to the longitudinal direction of the developing roller, and (b) is a state in which SiO ₂ portions are scattered within the range of the diameter of the elastic layer surface of 100 μm. It represents. As shown in FIG. 2, a region where the SiO ₂ portion is present between the elastic layer and the resin layer is mixed with a region where the SiO ₂ portion is not in contact with the elastic layer and the resin layer.

The present inventors have found that by forming the SiO ₂ portions interspersed between the elastic layer and the resin layer, it is possible to achieve both improvement in adhesion between the elastic layer and the resin layer and suppression of charge-up. “The portions formed of SiO ₂ are interspersed between the elastic layer and the resin layer” means that the SiO ₂ portions are not unevenly distributed between the elastic layer and the resin layer. It represents being done. That is, the region where the elastic layer and the resin layer are in contact and the region where the SiO ₂ portion exists between the elastic layer and the resin layer are present without any deviation.

In order to improve the adhesion between the elastic layer and the resin layer, it is effective to provide an intermediate layer having high adhesion with both. In the case where an intermediate layer is provided on the silicone rubber elastic layer, an SiO ₂ layer is exemplified. The reason why the silicone rubber improves the adhesion between the elastic layer and the resin layer is considered as follows. The molecular terminal of the silicone rubber forming the elastic layer is a methyl group. Since the methyl group forms only weak molecular bonds with the molecules forming the resin layer, the adhesion is low. On the other hand, in the SiO ₂ formed by subjecting the surface of the silicone rubber elastic layer to surface treatment such as corona treatment, the molecular ends are OH groups. Therefore, when SiO ₂ is on the surface of the elastic layer, the OH group at the SiO ₂ molecule terminal and the molecule forming the resin layer form a hydrogen bond. This is considered to improve the adhesion. However, since SiO ₂ generally has high resistance, when an image is formed using a developing roller in which a layer of SiO ₂ is uniformly formed as an intermediate layer, adverse effects due to charge-up are likely to occur.

Accordingly, the present inventors result of intensive studies the relationship between the distribution state and the charge-up of the SiO ₂ portion, be formed so as to scattered the SiO ₂ portion between the elastic layer and the resin layer, the charge-up It was found to be effective for suppression. With the configuration described above, since the portions where the elastic layer and the resin layer are in contact with each other without interposing the SiO ₂ portion, the charge charged up on the surface of the developing roller can be released to the shaft core body. It is thought that. Furthermore, since the adhesion between the elastic layer and the resin layer is enhanced by the scattered SiO ₂ portions, an effect of suppressing charge-up can be obtained uniformly over the entire developing roller without causing image density unevenness.

  That is, with the above-described configuration, it is possible to simultaneously improve the adhesion between the elastic layer and the resin layer and to suppress charge-up, and to suppress the change in image density during continuous paper feeding and the deterioration of fog after long-term use.

FIG. 2 is a schematic cross-sectional view when the developing roller of the present invention is cut in the axial direction. As shown in FIG. 2, the SiO ₂ portions 13 are formed interspersed between the elastic layer 12 and the resin layer 14.

The individual lengths of the scattered SiO ₂ portions preferably have a maximum length of 0.1 μm or more and less than 10 μm. The maximum length is the diameter of a circle circumscribing the SiO ₂ portion. By setting the maximum length to 0.1 μm or more, the adhesion of the resin layer by the SiO ₂ portion can be effectively obtained. Further, by setting the maximum length to less than 10 μm, it is possible to suppress image density unevenness due to local charge-up.

The thickness of the SiO ₂ portion is preferably 0.05 μm or more and 1 μm or less. By setting the thickness to 0.05 μm or more, it is possible to effectively obtain the adhesion of the resin layer by the SiO ₂ portion. Further, by setting the thickness to 1 μm or less, it is possible to suppress image density unevenness due to local charge-up.

The diameter and thickness of the SiO ₂ portion can be measured using a method such as TEM (transmission electron microscope). Details of the measurement method using TEM will be described later.

The SiO ₂ portion may contain at least 51% mainly containing SiO ₂ . Examples of components other than SiO ₂ include low-molecular components of cyclic polysiloxane and silicone rubber materials, but they may contain other components.

As a method for forming the SiO ₂ portion, an evaporation method such as a vacuum evaporation method, a sputtering method, or a CVD method can be used. By using these methods, it is possible to appropriately mask the SiO ₂ portion to obtain a desired distribution state. However, in the present invention, as a simple method for forming the SiO ₂ portion, a method for corona treatment of the silicone rubber surface has been found and adopted. It is possible to form the SiO ₂ portion by performing a corona treatment under specific conditions using a corona treatment apparatus described later.

The SiO ₂ portion is preferably formed over the entire length of the developing roller in order to obtain adhesion of the resin layer. Further, the amount of the SiO ₂ portion may be changed in the longitudinal direction of the developing roller. In particular, it is more preferable to form a large amount of the SiO ₂ portion at the end of the developing roller in order to improve the adhesion of the end.

Further, in the present invention, it is preferable that the abundance ratio R of the SiO ₂ portion on the elastic layer surface in the developing roller is 0.25 or more and 0.80 or less. Specifically, the value of R is obtained as follows.

By X-ray photoelectron spectroscopy, composition analysis in the depth direction within a diameter of 100 μm from the surface of the resin layer is performed. Then, a ratio R of the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms at the time when Si atoms attributed to Si—O derived from silicone rubber is detected is obtained. By setting the value of R to 0.25 or more, scattered SiO ₂ portions can be formed, and the adhesion between the elastic layer and the resin layer can be improved. Further, by setting the value of R to 0.80 or less, it is possible to prevent the can SiO ₂ successive layer, to suppress the charge-up. As shown in FIG. 7, the R is measured within the region from the end of the developing roller resin layer to 8% of the length of the developing roller in the longitudinal direction and the width of 8% of the length in the developing roller longitudinal direction. In the central region of the developing roller. At that time, R is measured at four points in the circumferential direction at the same position in the axial direction. Then, it is determined whether each R value is within the above range. Details of composition analysis by X-ray photoelectron spectroscopy will be described later.

Furthermore, it is preferable to change the ratio of the portion where the elastic layer and the resin layer are in contact with each other through the SiO ₂ portion at the end portion and the center portion in the longitudinal direction of the developing roller. Specifically, it is preferable that a relationship of Re × 0.50 ≦ Rc ≦ Re × 0.90 is established between Re and Rc obtained as described above. Here, Re is the value of R of the elastic layer in the end region of the developing roller. Rc is the value of R of the elastic layer in the central region of the developing roller. In the present invention, the end region of the developing roller refers to a region having a length of 8% with respect to the width of the developing roller from one end to the other end of the developing roller. The central region of the developing roller is a region having a length of 8% with respect to the middle point of the length along the axis of the developing roller (the width of the developing roller). By adopting such a configuration, the existence ratio of the SiO ₂ portion is larger in the end portion than in the center portion, and thus particularly improving the adhesion of the end portion that is likely to cause damage while maintaining charge-up suppression. Can be made.

By subjecting the silicone rubber elastic layer surface to corona treatment under specific conditions, SiO ₂ portions scattered on the elastic layer surface are formed. The SiO ₂ portion is considered to be formed as follows.

When corona treatment is applied to the silicone rubber at a certain or higher corona current density, the unreacted polysiloxane present in the elastic layer of the silicone rubber or the polysiloxane released by breaking the bond due to the high energy of corona discharge However, it gradually vaporizes. The vaporized polysiloxane is decomposed into Si atoms and O atoms by colliding with electrons and ions in corona discharge. Furthermore, Si atoms and O atoms are combined to form SiO ₂ on the elastic layer surface. As a result, it is considered that SiO ₂ portions scattered on the surface of the silicone rubber elastic layer are formed.

  The distance between the corona electrode and the elastic layer is 1 mm or more and 10 mm or less, and the average current density I (A / m) of the entire corona electrode during the corona treatment is 7.0 (A / m) or more and 35.0 ( A / m) or less.

In order to form the SiO ₂ portion interspersed, the average current density I (A / m) of the entire corona electrode during the corona treatment is 7.0 (A / m) or more and 35.0 (A / m) or less. It is preferable that By setting the average current density to 7.0 (A / m) or higher, it is possible to positively vaporize the polysiloxane by applying high thermal energy. The vaporized polysiloxane is decomposed in a high energy corona discharge to form a SiO ₂ portion. Further, by setting the average current density to 35.0 (A / m) or less, it is possible to prevent the polysiloxane from being excessively vaporized and forming a continuous layer of SiO ₂ . As a result, SiO ₂ portions scattered on the surface of the elastic layer can be formed.

In order to change the ratio of the portion where the elastic layer and the resin layer are in contact with each other through the SiO ₂ portion at the end portion and the center portion of the developing roller, it is effective to perform the corona treatment under the following conditions. That is, the average current density Ie (A / m) at the end and the average current density Ic (A / m) at the center are Ic × 1.2 (A / m) ≦ Ie ≦ Ic × 2.0 (A / m ) Is preferable. Here, Ie is the average current density in the region from the end of the resin layer during corona treatment to 8% of the length of the developing roller in the longitudinal direction, and Ic is 8% of the length in the longitudinal direction of the developing roller. The average current density in the central region of the developing roller. In this way, by adjusting the average current density at the end portion and the central portion, it is possible to manufacture a developing roller that satisfies the above-described relationship of Re × 0.50 ≦ Rc ≦ Re × 0.90.

To dotted form SiO ₂ portions microscopically, it is effective to control the surface roughness of the corona electrode. That is, it is preferable that the surface roughness Ra of the corona electrode is 1.0 μm or more and 3.0 μm or less. By appropriately roughening the surface of the corona electrode, the concentration of current density in the corona discharge can be dispersed microscopically, and the amount of polysiloxane vaporized and the amount of SiO ₂ formed can be controlled. As a result, it is possible to preferably control the condition of the SiO ₂ portion on the elastic layer.

In order to efficiently form the SiO ₂ portion, it is preferable to perform corona treatment after the surface of the elastic layer is heated to a temperature of 150 ° C. or higher and 220 ° C. or lower in advance. By heating the surface of the elastic layer to vaporize the polysiloxane in advance, a desired SiO ₂ portion can be formed with a short corona treatment, and damage to the elastic layer can be minimized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

<Developing roller of the present invention>
Hereinafter, the developing roller of FIG. 1 will be described in detail.

  The material of the shaft core body 11 is not particularly limited as long as it is conductive, and can be appropriately selected from carbon steel, alloy steel, cast iron, and conductive resin. Examples of the alloy steel include stainless steel, nickel chrome steel, nickel chrome molybdenum steel, chromium steel, chromium molybdenum steel, nitriding steel to which Al, Cr, Mo and V are added. Furthermore, as a rust prevention measure, the shaft core body can be plated and oxidized. As the type of plating, either electroplating or electroless plating can be used, but electroless plating is preferable from the viewpoint of dimensional stability. Examples of the electroless plating used here include nickel plating, copper plating, gold plating, Kanigen plating, and other various alloy plating. Examples of the nickel plating include Ni-P, Ni-B, Ni-WP, and Ni-P-PTFE composite plating. Each film thickness is preferably 0.05 μm or more, more preferably 0.10 μm to 30.00 μm.

  Silicone rubber is used as the material of the elastic layer 12. Silicone rubber may be used alone, or one or more kinds selected from natural rubber, isoprene rubber, styrene rubber, butyl rubber, butadiene rubber, fluorine rubber, and urethane rubber may be used in combination with silicone rubber.

  Examples of the silicone rubber material include the following. Polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polytrifluoropropylvinylsiloxane, polymethylphenylsiloxane, polyphenylvinylsiloxane, and copolymers of these polysiloxanes.

The silicone rubber constituting the elastic layer 12 preferably contains unreacted polysiloxane in order to form a desired SiO ₂ portion by corona treatment. Examples of the unreacted polysiloxane include low molecular components of various materials used as cyclic polysiloxane and silicone rubber. Normally, unreacted polysiloxane is contained in the silicone rubber, but the content may be controlled by blending a polysiloxane having no reactivity in advance. The developing roller of the present invention can be manufactured by corona-treating the silicone rubber elastic layer containing such unreacted polysiloxane under certain conditions. In particular, the content of unreacted polysiloxane contained in the silicone rubber is preferably 3 to 20% by weight. By making it 3% by weight or more, the formation of SiO ₂ is promoted, and by making it 20% by weight or less, it is possible to prevent siloxane from seeping out and contaminating the photoreceptor during image formation. The content of the unreacted polysiloxane contained in the silicone rubber is determined from the change in weight before and after the silicone rubber elastic layer was cut into an appropriate size and immersed in methyl ethyl ketone (MEK) for 24 hours to extract the polysiloxane. Can be sought.

  The thickness of the elastic layer 12 is preferably 0.5 mm to 10.0 mm in order to give the developing roller 10 sufficient elasticity. By setting the thickness of the elastic layer 12 to 0.5 mm or more, sufficient elasticity is obtained for the developing roller 10 and wear of the photosensitive drum can be suppressed. Moreover, the cost of the developing roller 10 can be suppressed by making the thickness of the elastic layer 12 10.0 mm or less.

  The elastic layer 12 preferably has an Asker-C hardness of 10 to 80 degrees. By setting the hardness of the elastic layer 12 to 10 degrees or more, it is possible to suppress the oil component from oozing out from the rubber material constituting the elastic layer 12 and to suppress contamination of the photosensitive drum. Further, by setting the hardness of the elastic layer 12 to 80 degrees or less, wear of the photosensitive drum can be suppressed. Further, the MD-1 hardness of the elastic layer 12 is set to 20.0 ° to 40.0 °, thereby suppressing the deformation amount of the elastic layer 12 by the contact member and the abrasion amount of the photosensitive drum by the elastic layer 12. This is preferable because it is possible. Here, MD-1 hardness means the value of micro rubber hardness measured in a room controlled at a temperature of 23 ° C. and a humidity of 50% RH using a micro rubber hardness meter MD-1 type manufactured by Kobunshi Keiki Co., Ltd. .

  A filler may be added to the elastic layer 12 as long as the low hardness and low compression set characteristics of the silicone rubber are not impaired. Filler materials include quartz fine powder, fumed silica, wet silica, diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, sulfuric acid Examples include aluminum, calcium sulfate, barium sulfate, glass fiber, organic reinforcing agent, and organic filler. The surface of these fillers may be hydrophobized by treatment with an organosilicon compound such as polydiorganosiloxane.

The developing roller 10 needs to have an electric resistance value of the semiconductor region. Therefore, the elastic layer 12 preferably contains a conductive agent and is formed of a rubber material having a volume resistivity of 1 × 10 ⁴ Ω · cm to 1 × 10 ⁸ Ω · cm. Here, if the volume resistivity of the resin layer material is a 1 × 10 ⁵ Ω · cm to 1 × ¹⁰ 10 Ω · cm, it is possible to obtain a uniform charge control with respect to the toner. More preferably, it is 1 × 10 ⁵ Ω · cm to 1 × 10 ⁹ Ω · cm.

  The volume resistivity of the resin layer material can be measured by the following method.

  First, a flat test piece is produced by curing the material of the elastic layer 12 to the same thickness as the elastic layer 12 under the same conditions as those for forming the elastic layer 12. Next, a test piece having a diameter of 30 mm is cut out from the test piece. On one side of the cut specimen, a vapor deposition film electrode (back electrode) is provided by performing Pt—Pd vapor deposition on the entire surface, and the main electrode film having a diameter of 15 mm is formed on the other surface by the same Pt—Pd vapor deposition film. A guard ring electrode film having an inner diameter of 18 mm and an outer diameter of 28 mm is provided concentrically. The Pt—Pd vapor-deposited film is obtained by performing a vapor deposition operation for 2 minutes at a current value of 15 mA using mild sputter E1030 (manufactured by Hitachi, Ltd.). The sample after the vapor deposition operation is used as a measurement sample.

Next, the volume resistance of the measurement sample is measured under the following conditions using the following apparatus. At the time of measurement, the main electrode is placed so as not to protrude from the main electrode film of the measurement sample. Further, the guard ring electrode is placed so as not to protrude from the guard ring electrode film of the measurement sample. The measurement is performed in an environment having a temperature of 23 ° C. and a humidity of 50% RH. Prior to the measurement, the measurement sample is left in the environment for 12 hours or more.
Sample box: Sample box TR42 (manufactured by Advantest) for measuring ultrahigh resistance meter
Main electrode: Metal guard ring electrode having a diameter of 10 mm and a thickness of 10 mm: Metal resistance meter having an inner diameter of 20 mm and an outer diameter of 26 mm and a thickness of 10 mm: Ultrahigh resistance meter R8340A (manufactured by Advantest)
Measurement mode: Program mode 5 (charge and measure 30 seconds, discharge 10 seconds)
Applied voltage: 100 (V)
When the measured volume resistance value is RM (Ω) and the thickness of the test piece is t (cm), the volume resistivity RR (Ωcm) of the resin layer material can be obtained by the following equation.
RR (Ωcm) = π × 0.75 × 0.75 × RM (Ω) ÷ t (cm)
As a means for making the material of the elastic layer 12 conductive, there is a technique of making the material conductive by adding a conductivity-imparting agent based on an ionic conduction mechanism or an electronic conduction mechanism to the material.

Examples of the conductivity imparting agent based on the ion conduction mechanism include the following. LiCF ₃ SO ₃ , NaClO ₄ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KSCN, NaCl Group 1 metal salt, NH ₄ Cl, (NH ₄ ) ₂ SO ₄ , NH ₄ NO 3 ammonium salt , Ca (ClO ₄ ) ₂ , Ba (ClO ₄ ) ₂ Periodic Table Group 2 metal salts, polyvalents of these salts and 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol Complexes of alcohols and their derivatives, complexes of these salts with ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether monools, and cationic properties of quaternary ammonium salts World Active agent, aliphatic sulfonates, alkyl sulfates, anionic surfactants alkyl phosphoric acid ester salt, an amphoteric surfactant betaine.

  Moreover, the following are mentioned as a conductive provision agent by an electronic conductive mechanism. Carbon black, carbonaceous material of graphite, aluminum, silver, gold, tin-lead alloy, copper-nickel alloy metal or alloy, zinc oxide, titanium oxide, aluminum oxide, tin oxide, antimony oxide, indium oxide, silver oxide Metal oxide, various fillers plated with copper, nickel, silver conductive metal. These conductivity-imparting agents based on the ion conduction mechanism and the electron conduction mechanism can be used alone or in a mixture of two or more in the form of powder or fiber. Among these, carbon black is preferably used from the viewpoint that the conductivity can be easily controlled and is economical.

  Examples of the material used for the resin layer 14 include the following. Epoxy resin, diallyl phthalate resin, polycarbonate resin, fluororesin, polypropylene resin, urea resin, melamine resin, silicon resin, polyester resin, styrene resin, vinyl acetate resin, phenol resin, polyamide resin, fiber resin, urethane resin, Silicone resin, acrylic urethane resin, water-based resin. It is also possible to use a combination of two or more of these. Among these, it is particularly preferable to use a urethane resin or an acrylic urethane resin which is a nitrogen-containing compound because the toner can be stably charged. Furthermore, it is more preferable to use a urethane resin obtained by reacting an isocyanate compound and a polyol from the viewpoint of charge imparting properties and suppression of toner deterioration.

  The following are mentioned as an isocyanate compound. Diphenylmethane-4,4′-diisocyanate, 1,5-naphthalene diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, p-phenylene diisocyanate, isophorone diisocyanate, Carbodiimide-modified MDI, xylylene diisocyanate, trimethylhexamethylene diisocyanate, tolylene diisocyanate, naphthylene diisocyanate, paraphenylene diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl polyisocyanate. Moreover, these mixtures can also be used and the mixing ratio may be any ratio.

  Moreover, the following are mentioned as a polyol used here. As a divalent polyol (diol), ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, hexanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,1,1-trimethylolpropane, glycerin, pentaerythritol, sorbitol as xylene glycol, triethylene glycol, trivalent or higher polyol. Furthermore, polyols such as high molecular weight polyethylene glycol, polypropylene glycol, and ethylene oxide-propylene oxide block glycol obtained by adding ethylene oxide and propylene oxide to diol and triol can be used. Moreover, these mixtures can also be used and the mixing ratio may be any ratio.

  Furthermore, the resin layer 14 can be used by imparting conductivity. As a method for imparting conductivity, it is possible to use a method similar to the method for making the elastic layer 12 conductive.

  The thickness of the resin layer 14 is preferably 1.0 μm to 500.0 μm. Furthermore, the thickness of the resin layer 14 is more preferably 1.0 μm to 50.0 μm. Durability can be given by making the resin layer 14 1.0 μm or more. Further, by setting the thickness to 500.0 μm or less, more preferably 50.0 μm or less, the MD-1 hardness can be lowered, and toner adhesion can be suppressed. In the case of forming a plurality of resin layers, it is desirable that the thickness of the entire plurality of layers be in the above range. Here, the thickness of the resin layer 14 is measured from the flat part on the surface of the resin layer to the interface on the elastic layer side using a digital microscope VHX-600 manufactured by Keyence Corporation. Mean distance.

  It is preferable to set the MD-1 hardness of the developing roller 10 to 30.0 ° to 50.0 ° because toner adhesion and deformation due to the contact member can be effectively suppressed. Here, MD-1 hardness means the value of micro rubber hardness measured in a room controlled at a temperature of 23 ° C. and a humidity of 50% RH using a micro rubber hardness meter MD-1 type manufactured by Kobunshi Keiki Co., Ltd. .

  The surface roughness of the developing roller 10 greatly affects the toner conveying force, and the center line average roughness Ra in the standard of JIS B 0601: 1994 surface roughness is preferably 0.05 μm to 3.00 μm. By setting Ra to 0.05 μm or more, it is possible to obtain a toner conveying force, and it is possible to suppress a decrease in image quality such as a decrease in image density and a ghost. Further, by setting Ra to 3.00 μm or less, it is possible to suppress deterioration in image quality such as fogging and roughness.

  As a means for controlling the surface roughness, it is effective to make the resin layer 14 contain particles having a desired particle diameter. It is also possible to form a desired surface roughness by appropriately performing a polishing treatment before and after forming the resin layer. In that case, when only the elastic layer is formed, polishing treatment may be performed after the elastic layer is formed. In the case where a plurality of elastic layers are formed, polishing treatment may be performed after the formation of the plurality of layers. When the elastic layer and the resin layer are formed, the resin layer may be formed after the elastic layer is formed and then the polishing process may be performed, or the polishing process may be performed after the resin layer is formed.

  As the particles to be contained in the resin layer 14, metal particles and resin particles having a particle diameter of 0.1 μm to 30.0 μm can be used. Among these, resin particles that are highly flexible, have a relatively small specific gravity, and easily obtain the stability of the paint are more preferable. Examples of the resin particles include urethane particles, nylon particles, acrylic particles, and silicone particles. These resin particles can be used alone or in combination of two or more. In the case where a plurality of resin layers are formed, all of the plurality of layers may contain particles, or at least one of the plurality of layers may contain particles.

<Corona treatment apparatus according to the present invention>
The outline of the corona treatment apparatus applicable to the present invention will be described with reference to FIG.

  FIG. 3 is a schematic configuration diagram showing an example of a corona treatment device that realizes the developing roller manufacturing method of the present invention.

  In FIG. 3, a corona treatment apparatus 30 includes a chamber 31, a corona ammeter 32, a high frequency power source 33, a gas introduction port 34, a gas exhaust port 35, a support unit 36, a rotation drive unit 37, a purge port 38, a pulse generator 39, a corona. The electrode 40 is configured. An example of the corona treatment device is a corona discharge surface treatment device (manufactured by Kasuga Denki Co., Ltd.).

  The developing roller 10, which is an object to be processed, is supported at both ends of the cored bar by a support portion 36 installed in the chamber 31, and is arranged in parallel with the corona electrode 40 at a desired interval. Further, the shaft core body of the developing roller 10 is grounded via the support portion 36 and is connected to the rotation drive portion 37.

  The corona electrode 40 is insulated from the chamber 31 and further connected to a high frequency power source 33 that outputs high frequency power of a desired frequency. A pulse generator 39 is connected to the high frequency power supply 33, and the high frequency power can be pulse-modulated as necessary.

  A corona ammeter 32 is connected between the corona electrode 40 and the high-frequency power source 33, and the current value supplied to the corona discharge can be measured. The average current density I (A / m) of the entire corona electrode during corona treatment according to the present invention can be calculated by dividing this current value by the length of the corona discharge generation region in the longitudinal direction of the elastic layer. The length of the corona discharge generation region was measured by visually confirming the generation of corona discharge.

  The corona electrode 40 is preferably composed of a metal conductor portion that supplies high-frequency power and an insulator portion that covers the periphery thereof in order to suppress the occurrence of abnormal discharge. Specifically, as shown in FIG. 4A, the insulator portion 42 is covered around the conductor portion 41. The conductor portion 41 is not particularly limited as long as it is a conductor, but it is preferable to use Al or Cu. The insulator portion 42 is not particularly limited as long as it is insulative, but it is preferable to use ceramic in terms of durability.

  In the present invention, in order to individually control the average current density Ie (A / m) at the end of the resin layer and the average current density Ic (A / m) at the center, the metal conductor portion 41 of the corona electrode is provided. It is possible to divide in a desired region and control the corona ammeter 32, the high-frequency power source 33, and the pulse generator 39 individually and control them independently.

  Further, as shown in FIG. 4B, the diameter of the insulator portion 42 of the corona electrode 40 is controlled in the longitudinal direction, and as shown in FIG. 4C, the diameter of the conductor portion 41 is controlled in the longitudinal direction. By doing so, it is also possible to control the average current density Ie (A / m) at the end of the resin layer and the average current density Ic (A / m) at the center. In this case, the diameter of the conductor part 41 and the thickness of the insulator part 42 may be appropriately adjusted and used so that each has a desired current density.

The surface roughness of the corona electrode is effective in forming a desired SiO ₂ portion on the elastic layer surface. Specifically, the center line average roughness Ra in the standard of JIS B 0601: 1994 surface roughness is more preferably 1.0 μm or more and 3.0 μm or less. By setting Ra to 1.0 μm or more, the current density during corona discharge can be made non-uniform, and desired SiO ₂ portions can be scattered and formed. Moreover, the abnormal discharge which generate | occur | produces by producing electric field concentration in corona discharge can be suppressed by Ra being 3.0 micrometers or less. The surface roughness of the corona electrode can be controlled to a desired value by general polishing or blasting.

  In order to make the inside of the chamber 31 have a desired gas atmosphere, the gas inlet 34 is connected to a gas cylinder (not shown) via a regulator, and the gas exhaust port 35 is connected to a vacuum pump (not shown). In addition, a purge port 38 for purging the inside of the chamber 31 is provided.

  Further, an infrared halogen lamp for heating the surface of the elastic layer may be installed in order to easily vaporize unreacted polysiloxane.

  Next, the operation of the corona treatment device will be described.

  First, the developing roller 10 that performs corona treatment is installed at a desired position. Next, the developing roller 10 is driven to rotate. Thereafter, desired high-frequency power is supplied from the high-frequency power source 33 to the corona electrode 40, and corona discharge is generated between the developing roller 10 and the corona electrode 40 to start processing. When the desired processing time has elapsed, the supply of electric power and rotational driving are stopped, the developing roller 20 is taken out, and the processing is completed.

Conditions for generating corona discharge need to be adjusted as appropriate so that a desired SiO ₂ portion can be formed. In particular, if the corona discharge becomes unstable and the occurrence of abnormal discharge or excessive temperature rise of the elastic layer may cause damage to the elastic layer, it must be avoided.

The time for the corona treatment is preferably selected as appropriate so that a desired SiO ₂ portion can be formed. Specifically, the treatment time is preferably 30 seconds or longer and 120 seconds or shorter. Setting it to 30 seconds or more is preferable because a uniform treatment effect can be obtained in the circumferential direction. Moreover, since it can suppress the damage of the elastic layer by excessive temperature rising by setting it as 120 seconds or less, it is preferable.

  The pressure in the chamber 31 at the time of generating the corona discharge is not particularly limited. However, in order to increase the charged particle density during the corona discharge and to perform the treatment efficiently, the corona discharge is performed near the atmospheric pressure of 92 kPa to 111 kPa. It is preferable to form and process.

The high frequency power supplied to the corona electrode 40 is preferably selected as appropriate for the frequency and the input power. Specifically, a frequency of 1 kHz to 3 GHz is preferable. In particular, when corona discharge is generated in the atmosphere, 1 kHz to 15 MHz is preferable, and 5 to 100 kHz is more preferable because corona discharge can be stably formed. The input power is not particularly limited because it depends on the device configuration and the corona discharge generation region, but the desired SiO ₂ portion can be formed more efficiently if it is increased within the range where abnormal discharge does not occur and the elastic layer does not overheat. This is preferable because it is possible.

In the present invention, it is more preferable to generate corona discharge by supplying high-frequency power pulse-modulated by a pulse width modulation method. By using the pulse width modulation method, the power input to the corona discharge can be set high, and a desired SiO ₂ portion can be easily obtained. The duty ratio is preferably in the range of 50% to 80%. The duty ratio represents a ratio of time for applying power to one cycle of pulse-modulated high-frequency power. A duty ratio of 50% or more is preferable because sufficient energy can be given to obtain a desired SiO ₂ portion. Further, it is preferable to set the duty ratio to 80% or less because damage to the elastic layer caused by excessive temperature rise due to corona discharge can be suppressed.

  The distance between the corona electrode 40 and the elastic layer 20 is not particularly limited as long as it is substantially uniform in the longitudinal direction. An appropriate range may be selected in accordance with the power supply frequency to be used so that the corona discharge is stably formed, but generally an interval of 1 mm to 10 mm is preferable. The thickness of 1 mm or more is preferable because the occurrence of abnormal discharge can be suppressed. Moreover, since it can form uniformly a corona discharge by setting it as 10 mm or less, it is preferable.

  The generation area of the corona discharge can be arbitrarily controlled by the apparatus configuration. As shown in FIG. 3, by installing the corona electrode 40 so as to face the entire elastic layer 10, a corona discharge can be formed in the entire longitudinal direction of the elastic layer 10 and processed simultaneously. Alternatively, the entire longitudinal direction of the elastic layer 10 may be processed by scanning a corona discharge formed in a part of the elastic layer 10 in the longitudinal direction in the longitudinal direction of the elastic layer 10. As an example of a corona treatment device that generates such corona discharge, there is a plasma irradiation surface modification device PS-601C (manufactured by Kasuga Electric Co., Ltd.).

  The corona treatment is preferably performed uniformly in the circumferential direction by rotating the developing roller. The rotation speed of the developing roller is not particularly limited, but a rotation speed of 1 rpm to 300 rpm is preferable because it can be uniformly processed.

In addition, heating the surface of the elastic layer before performing the corona treatment is preferable because the SiO ₂ portion can be efficiently formed. In this case, it is preferable to rotate the developing roller and heat it for 10 to 300 seconds so that the unreacted polysiloxane is easily vaporized to bring the elastic layer surface to a temperature of 150 to 220 ° C. The heat source is not particularly limited, but an infrared halogen lamp is preferable from the viewpoint of cost and temperature increase rate.

If the corona treatment apparatus as described above is used, a desired SiO ₂ portion can be formed on the elastic layer surface.

<Electrophotographic image forming apparatus and electrophotographic process cartridge according to the present invention>
Next, an example of an electrophotographic image forming apparatus equipped with the developing roller of the present invention will be described with reference to FIG. In the following example, a color electrophotographic image forming apparatus will be described. However, the developing roller of the present invention can also be used for a monochrome electrophotographic image forming apparatus.

  In FIG. 5, the image forming apparatus 500 for electrophotography is provided with image forming units a, b, c, and d provided for each color toner of yellow toner, magenta toner, cyan toner, and black toner. Each image forming unit is provided with a photoreceptor 505 as an electrostatic latent image carrier that rotates in the direction of the arrow. Around each photoconductor, a charging device 511 for uniformly charging the photoconductor, exposure means for irradiating the uniformly charged photoconductor with laser light 510 to form an electrostatic latent image, electrostatic A developing device 509 is provided that supplies toner to the photosensitive member on which the latent image is formed to develop the electrostatic latent image.

  On the other hand, a transfer conveyance belt 520 that conveys a recording material 522 such as paper supplied by a paper supply roller 523 is provided suspended from a drive roller 516, a driven roller 521, and a tension roller 519. The transfer / conveying belt 520 is charged with the charge of the suction bias power source 525 via the suction roller 524 so that the recording material 522 is electrostatically attached to the surface and transported.

  A transfer bias power source 518 is provided to apply a charge for transferring the toner image on the photosensitive member of each image forming unit to the recording material 522 conveyed by the transfer conveyance belt 520. The transfer bias is applied via a transfer roller 517 disposed on the back surface of the transfer conveyance belt 520. The toner images of the respective colors formed in the image forming units are sequentially superimposed and transferred onto a recording material 523 conveyed by a transfer conveying belt 520 that is moved in synchronization with the image forming unit. .

  Further, in the color electrophotographic image forming apparatus, a fixing device 515 for fixing the toner image superimposed and transferred on the recording material by heating or the like, and a conveying device (not shown) for discharging the image-formed recording material 522 to the outside of the apparatus. Is provided.

  On the other hand, each image forming unit is provided with a cleaning device 512 having a cleaning blade for removing residual toner remaining without being transferred onto each photoreceptor and cleaning the surface. Further, a waste toner container for storing toner scraped off from the photoreceptor is provided. The cleaned photoconductor is set in an image-formable state and stands by.

  A developing device 509 provided in each of the image forming units is provided with a toner container 507 containing non-magnetic toner as a one-component developer, and a toner container that closes the opening of the toner container. A developing roller 10 is provided so as to face the body.

  In the toner container, toner is supplied to the developing roller, and at the same time, a toner supply roller 506 for scraping off toner that is not used on the developing roller after development, and the toner on the developing roller are formed in a thin film shape. In addition, a toner amount regulating member 508 that is frictionally charged is provided. These are disposed in contact with the developing roller 10, respectively. A toner amount regulating member bias power source 513 is connected to the toner amount regulating member 508, a developing roller bias power source 514 is connected to the developing roller, and electric charges are respectively applied to the toner amount regulating member and the developing roller during image formation. The The voltage output from the toner amount regulating member bias power supply 513 is 50V to 400V lower than the voltage output from the developing roller bias power supply 514.

  Next, an example of an electrophotographic process cartridge detachable from an electrophotographic image forming apparatus equipped with the developing roller of the present invention will be described with reference to FIG. The process cartridge 530 for an electrophotographic image forming apparatus shown in FIG. 6 has a developing device 509, a photoreceptor 505, and a cleaning device 512, which are integrated and detachably provided on the main body of the electrophotographic image forming apparatus. It is done. Examples of the developing device 9 include the same ones as described in the electrophotographic image forming apparatus. In addition to the above, the process cartridge for an electrophotographic image forming apparatus of the present invention may be one in which a transfer member for transferring a toner image on a photosensitive member to a recording material is integrally provided with the above members.

<Analysis method according to the present invention>
(Confirmation of SiO ₂ part by transmission electron microscope)
In the present invention, it was confirmed by a transmission electron microscope that the elastic layer and the resin layer were in contact with each other through the SiO ₂ portion.

As a sample, a developing roller to be measured was cut out in a cross-sectional direction so as to include both an elastic layer and a resin layer, and then cut with a microtome to produce a 100 μm square and a 100 nm thick flake. This sample was observed at a magnification of 10,000 times using a transmission electron microscope (trade name: H-7500, manufactured by Hitachi High-Technologies Corporation), and the presence or absence of a SiO ₂ portion was confirmed between the elastic layer and the resin layer. At the same time, as shown in FIG. 2A, it was confirmed whether a portion where the elastic layer and the resin layer are in contact with each other via the SiO ₂ portion and a portion where the elastic layer and the resin layer are in contact without using the SiO ₂ portion are mixed. Furthermore, the diameter and thickness of the SiO ₂ part were confirmed.

(Quantitative analysis of SiO ₂ part by X-ray photoelectron spectroscopy)
In the present invention, quantitative analysis of the SiO ₂ portion was performed by X-ray photoelectron spectroscopy.

  The sample was produced by cutting out a depth of 1 mm or more so that both the elastic layer and the resin layer were sufficiently contained at 5 mm square from the surface of the developing roller to be measured. This sample was subjected to composition analysis in the depth direction from the resin layer surface of the sample by an argon ion etching method using an X-ray photoelectron spectrometer (trade name: Quantum 2000, manufactured by ULVAC-PHI Co., Ltd.). Here, the analysis region was set to φ100 μm, and Al Kα (15 kV, 25 W) was used as the X-ray source. Furthermore, composition information was obtained every time etching was performed at about 100 nm, and composition analysis in the depth direction was performed.

Specifically, the peak due to the binding energy of Si 2p orbit is measured, the Si peak attributed to SiO ₂ is 103.7 eV, and the Si peak attributed to Si—O is 102.5 eV. Peak separation was performed. From the composition of Si attributed to each bond, the ratio R of the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms at the time when Si atoms attributed to Si—O derived from the elastic layer were detected was obtained. It was.

An example of the measurement result is shown in Table 1. In Table 1, the composition of Si atoms attributed to Si—O and Si atoms attributed to SiO ₂ at relative positions in the depth direction every 100 nm, and the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms. The ratio R was shown. In Table 1, the relative position in the depth direction is shown only in the vicinity of the SiO ₂ portion. Moreover, the composition analysis result measured was set to 100 (atom%) as the total number of detected carbon, nitrogen, oxygen, and silicon.

Here, the time when the composition of Si atoms attributed to Si-O becomes 1/2 or more of the composition of Si atoms attributed to Si-O in the elastic layer is attributed to Si-O derived from the elastic layer. It was defined as the point in time when Si atoms to be detected were detected. In the measurement example of Table 1, the composition of Si atoms attributed to Si—O in the elastic layer was 20 (atom%). Therefore, it was judged that Si atoms belonging to Si—O derived from the elastic layer were detected at the relative position 13 in the depth direction. At this time, the ratio R of the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms was 0.36.

In this way, the ratio R of the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms at the time when Si atoms attributed to Si—O derived from the elastic layer were detected was determined.

  Hereinafter, the present invention will be described in detail based on examples and comparative examples.

  The following examples are examples of the best mode of the present invention, but the present invention is not limited to these examples.

[Example 1-1]
<Production of developing roller>
By the following procedure, a developing roller was produced in which an elastic layer and a resin layer were provided as a coating layer around a cylindrical shaft core.

  As the shaft core body, a SUS304 metal core having a diameter of 6 mm and a length of 279 mm was used.

As a material for the elastic layer, liquid silicone rubber was prepared in the following manner. First, the following materials were mixed to form a liquid silicone rubber base material.
Dimethylpolysiloxane having a vinyl group at both ends and a viscosity of 100 Pa · s at a temperature of 25 ° C. (manufactured by Toray Dow Corning, weight average molecular weight 100,000): 100 parts by mass.
Quartz powder (manufactured by Pennsylvania Glass Sand, trade name: Min-USil) as a filler: 7 parts by mass.
8 parts by mass of carbon black (manufactured by Denki Kagaku Kogyo, trade name: Denka Black, powdered product). To this base material, a platinum compound (Toray Dow Corning, 1% Pt concentration) as a curing catalyst, and an organohydrogenpolysiloxane having SiH groups at both molecular chain ends and side chains (Toray Dow Corning) A product obtained by blending 3 parts by mass with a weight average molecular weight of 500) was mixed at a mass ratio of 1: 1 to obtain a liquid silicone rubber.

  A shaft core is placed in the center of a cylindrical mold with an inner diameter of 12 mm, and this liquid silicone rubber is injected into the cylindrical mold from the injection port, heated and cured at 120 ° C. for 5 minutes, and cooled to room temperature. The elastic layer integrated with the shaft core was removed. Further, the curing reaction was completed by heating at a temperature of 150 ° C. for 4 hours, and an elastic layer mainly composed of silicone rubber having a thickness of 3 mm was provided on the outer peripheral surface of the shaft core body. The content of unreacted polysiloxane in the silicone rubber was 10% by weight.

Then treated in the following manner by a corona treatment apparatus shown in FIG. 3 (Kasuga Electric Works Ltd.) to form a SiO ₂ portion in the elastic layer surface.

  The elastic layer was disposed at a distance of 3 mm from the corona electrode in a corona treatment apparatus installed in a room controlled at a temperature of 23 ° C. and a humidity of 50% RH. The length of the corona electrode was 300 mm, and the surface roughness Ra was 2.0 μm. The atmosphere in the chamber was kept as room air, and the pressure was 101 kPa.

  After confirming that the elastic layer surface has a temperature of 23 ° C., the elastic layer is rotated at a rotation speed of 60 rpm, and then the elastic layer surface is heated to a temperature of 200 ° C. using an infrared halogen lamp (manufactured by Iwasaki Electric Co., Ltd.). And then left for 1 minute.

  Thereafter, the electric power of frequency 35 kHz was supplied with a corona current density of 20 (A / m) uniformly in the longitudinal direction without performing pulse modulation to perform corona treatment. The processing time was 30 seconds.

  Next, the resin layer was coated as follows.

The following materials were used as the material for the resin layer.
Polytetramethylene glycol (trade name: PTG650SN, number average molecular weight Mn = 1000, f = 2 (f represents the number of functional groups; the same shall apply hereinafter); manufactured by Hodogaya Chemical Co., Ltd.): 100.0 parts by mass. Isocyanate (trade name: Millionate MT, MDI, f = 2, manufactured by Nippon Polyurethane Industry Co., Ltd.): 21.2 parts by mass.
These materials are mixed stepwise in a MEK solvent and reacted at 80 ° C. for 6 hours under a nitrogen atmosphere. The weight average molecular weight Mw = 10000, the hydroxyl value 20.0 (mg · KOH / g), and the molecular weight dispersity Mw. A bifunctional polyurethane prepolymer having /Mn=2.9 and Mz / Mw = 2.5 was obtained. MEK is methyl ethyl ketone.

  30.0 parts by mass of isocyanate (trade name: Coronate 2521, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 100.0 parts by mass of this polyurethane prepolymer so that the NCO equivalent was 1.4. The NCO equivalent represents a ratio ([NCO] / [OH]) between the number of moles of isocyanate groups in the isocyanate compound and the number of moles of hydroxyl groups in the polyol component.

  Furthermore, 21.0 parts by mass of carbon black (trade name: # 1000, pH 3.0, manufactured by Mitsubishi Chemical Corporation) was added. An organic solvent was added to the raw material mixture, and the solid content was appropriately adjusted in the range of 20% by mass to 30% by mass so as to obtain a film thickness of about 20 μm. Furthermore, 21.0 parts by mass of urethane resin particles (trade name: C400 transparent, diameter 14 μm, manufactured by Negami Kogyo Co., Ltd.) were added, uniformly dispersed, and mixed to obtain a raw material liquid for the resin layer.

  The shaft core body on which the resin layer was formed was immersed in the resin layer raw material liquid, and then pulled up and allowed to dry naturally. Next, a heat treatment was performed at a temperature of 140 ° C. for 60 minutes to cure the resin layer raw material liquid to obtain a resin layer having an average thickness of 20.0 μm. In this way, a developing roller having an outer diameter of about 12 mm, a coating layer length of 235 mm, and a centerline average roughness Ra of 1.5 μm according to JIS B 0601: 1994 surface roughness standards was produced.

<Evaluation>
The developing roller produced according to the method the foregoing analysis, was confirmed SiO ₂ parts by transmission electron microscopy. As a result, a SiO ₂ portion was confirmed between the elastic layer and the resin layer.

At the same time, contact without the intervention and dotted with SiO ₂ portions as shown in FIG. 2 (a) and (b), a portion where the elastic layer and the resin layer in contact via the SiO ₂ portion, the SiO ₂ portion It was confirmed that the part was mixed.

Next, the maximum length of SiO ₂ was measured at a position 20 mm from the end of the developing roller and a central position in the longitudinal direction. At that time, four points were measured in the circumferential direction at the same position in the axial direction. When the SiO ₂ portion in the range of 25 μm square was observed with a transmission electron microscope, the maximum length of each was in the range of 0.1 μm or more and 10 μm or less, although there was some variation in size.

Next, quantitative analysis of the SiO ₂ portion by X-ray photoelectron spectroscopy was performed. As a result, the ratio R of the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms at the time when Si atoms attributed to Si—O derived from the elastic layer were detected was 0.56.

  Furthermore, image evaluation was performed with an electrophotographic image forming apparatus using a developing roller produced under the same conditions. For the electrophotographic image forming apparatus, Color Laser Jet 3600 manufactured by Hewlett-Packard Co. was used. A special black cartridge was used as the process cartridge, and only the developing roller was replaced, and the following evaluation was performed.

(Cover evaluation)
The process cartridge incorporating the developing roller of this embodiment was mounted on the main body of the image forming apparatus, and left in an environment of a temperature of 15 ° C. and a humidity of 10% RH for 24 hours. Thereafter, in this environment, 25,000 images having a printing rate of 1%, which is longer than the nominal life, were output. Thereafter, a solid white image was output in the same environment, and the fogging value was measured by the following method.

  The fog value is measured after the reflection density of the transfer paper before image formation and solid white image formation using a reflection densitometer (trade name: TC-6DS / A; manufactured by Tokyo Denshoku Technology Center Co., Ltd.). The reflection density of the transfer paper was measured and obtained from the difference.

The fogging value was evaluated according to the following criteria. It is considered that charge-up can be suppressed as the fogging value is smaller. Here, the following evaluation A and evaluation B are levels at which “fog” cannot be recognized visually. On the other hand, the evaluation C and the evaluation D are levels at which “fogging” can be clearly recognized visually.
A: Less than 1.0 B: 1.0 or more and less than 2.0 C: 3.0 or more and less than 5.0 D: 5.0 or more.

(Adhesion evaluation)
Next, the developing roller that had been subjected to the fog evaluation was taken out and left in an environment of a temperature of 20 ° C. and a humidity of 55% RH for 24 hours, and in the same environment, adhesion evaluation was performed by the following method.

  First, the surface of the developing roller was washed with methyl ethyl ketone to remove toner and toner-derived deposits. Next, a polyimide tape (model number: P-221, manufactured by Permacel) is pasted on the entire surface of the developing roller in the longitudinal direction, and a razor blade is used to cut a 10 mm width in the longitudinal direction from above the polyimide tape. I put it all over. After that, the cross-sections at both ends of the developing roller were cut using a razor blade almost parallel to the polyimide tape, and then the polyimide tape and the developing roller surface were peeled together at an angle of 90 ° with respect to the developing roller surface. The peel strength was measured using a tensile tester. As the surface of the developing roller is peeled off, peeling generally proceeds at the interface between the elastic layer and the resin layer where the peel strength is minimized, so that this method can evaluate the adhesion between the elastic layer and the resin layer. is there.

  Measurements were made on the entire length of the developing roller from both ends of the developing roller, and the minimum peel strength was evaluated according to the following criteria. It is considered that the greater the peel strength value, the better the adhesion of the resin layer of the developing roller even after long-term use.

Here, the following evaluation A and evaluation B are levels at which there is no problem in adhesion in actual use. On the other hand, the evaluation C and the evaluation D are levels that may cause a problem in adhesion when the developing roller is reused.
A: 200 gf or more B: 150 gf or more and less than 200 gf C: 80 gf or more and less than 100 gf D: 80 gf or less [Comparative Example 1]
After the elastic layer was formed, the developing roller manufactured in the same manner as in Example 1 was evaluated except that the excimer treatment was performed instead of the corona treatment and the resin layer was formed.

Excimer treatment was performed under the following conditions. The elastic layer surface is irradiated with a capillary excimer lamp (manufactured by Harrison Toshiba Lighting Co., Ltd.) capable of irradiating ultraviolet rays with a wavelength of 172 nm while rotating the shaft core at a rotation axis of 30 rpm so that the integrated light amount becomes 120 mJ / cm ^2. Was processed. The distance between the elastic layer surface and the excimer lamp at the time of irradiation was 2 mm.

As a result of evaluating the produced developing roller with a transmission electron microscope, no SiO ₂ portion was observed between the elastic layer and the resin layer.

[Comparative Example 2]
After forming the elastic layer, the developing roller manufactured in the same manner as in Example 1 was evaluated except that the SiO ₂ portion was uniformly formed by a sputtering apparatus instead of the corona treatment, and then the resin layer was formed.

The SiO ₂ portion was formed uniformly with a film thickness of 500 nm using a SiO ₂ target in a sputtering apparatus (trade name: E-200S, manufactured by Canon Anelva Engineering).

As a result of evaluating the produced developing roller with a transmission electron microscope, it was confirmed that a continuous SiO ₂ portion was formed between the elastic layer and the resin layer.

[Comparative Example 3]
After the elastic layer was formed, the developing roller manufactured in the same manner as in Example 1 was evaluated except that the resin layer was formed after changing the corona treatment conditions as follows.

  The conditions of the corona treatment were as follows: the surface roughness Ra of the corona electrode was 0.5 μm, the elastic roller surface was not heated and kept at room temperature, the current density was 5.0 (A / m), and the treatment time was 10 seconds. Except for the above, corona treatment was performed under the same conditions as in Example 1.

As a result of evaluating the produced developing roller with a transmission electron microscope, no SiO ₂ portion was observed between the elastic layer and the resin layer.

  The above evaluation results are shown together in Table 2.

From the results of Table 2, in Example 1 in which the region in which the elastic layer and the resin layer are in contact with each other through the SiO ₂ portion and the region in which the elastic layer and the resin layer are in contact with each other without using the SiO ₂ portion are mixed, the adhesion of the resin layer is improved. It has been found that it is possible to provide a developing roller that can simultaneously suppress fogging due to charge-up.

[Example 1-2]
Other than changing the amount of unreacted polysiloxane contained in the silicone rubber used in the elastic layer by changing the effect reaction conditions of the elastic layer, heating at 150 ° C. for 6 hours to complete the curing reaction, The developing roller manufactured in the same manner as in Example 1 was evaluated. The content of unreacted polysiloxane in the silicone rubber was 3% by weight. Moreover, as a result of measuring the maximum length of SiO _{2 in} the same manner as in Example 1-1, the maximum length of SiO ₂ was in the range of 0.1 μm to 10 μm.

[Example 1-3]
Manufactured in the same manner as in Example 1 except that 10 parts by mass of cyclic polysiloxane (trade name: DC246 Fluid, manufactured by Toray Dow Corning Co., Ltd.) is added and mixed as a material for the elastic layer to obtain a liquid silicone rubber base material. The developed roller was evaluated. The content of unreacted polysiloxane in the silicone rubber was 20% by weight. Moreover, as a result of measuring the maximum length of SiO _{2 in} the same manner as in Example 1-1, the maximum length of SiO ₂ was in the range of 0.1 μm to 10 μm.

[Examples 2-1 to 2-11]
As shown in Table 3, the average current density Ie (A / m) and the length in the longitudinal direction of the developing roller in the region up to 8% of the length of the developing roller in the longitudinal direction from the end of the resin layer during corona treatment The developing roller manufactured in the same manner as in Example 1 was evaluated except that the average current density Ic (A / m) in the central region of the developing roller having an 8% width was controlled.

[Example 3]
Further, as shown in Table 3, the developing roller manufactured in the same manner as in Example 1 was evaluated except that the surface roughness of the corona electrode was changed and the average current density I was 20.0 (A / m). went.

[Example 4]
Furthermore, as shown in Table 3, except that the temperature of the elastic layer surface at the start of corona treatment was changed, the average current density I was 10.0 (A / m), and the corona treatment time was 10 seconds. The developing roller manufactured in the same manner as in Example 1 was evaluated.

[Example 5-1]
Furthermore, the effect reaction conditions of the elastic layer were changed, and the curing reaction was completed by heating at a temperature of 150 ° C. for 8 hours, thereby changing the amount of unreacted polysiloxane contained in the silicone rubber used in the elastic layer. As a result, the content of unreacted polysiloxane in the silicone rubber was 1% by weight.

  Furthermore, as shown in Table 3, the developing roller produced in the same manner as in Example 1 was evaluated except that Ie (A / m) and Ic (A / m) were controlled.

Further, the maximum length of SiO ₂ was measured in the same manner as in Example 1-1. One in which the maximum length of SiO ₂ was not within the range of 0.1 μm to 10 μm was observed.

[Example 5-2]
Furthermore, as a material for the elastic layer, 15 parts by mass of cyclic polysiloxane (manufactured by Toray Dow Corning, trade name: DC246 Fluid) was added and mixed to obtain a liquid silicone rubber base material. As a result, the content of unreacted polysiloxane in the silicone rubber was 20% by weight.

  Further, as shown in Table 3, the temperature of the elastic layer surface at the start of the corona treatment and Ie (A / m) and Ic (A / m) at the time of the corona treatment were controlled as in Example 1. The developing roller manufactured as described above was evaluated.

Further, the maximum length of SiO ₂ was measured in the same manner as in Example 1-1. One in which the maximum length of SiO ₂ was not within the range of 0.1 μm to 10 μm was observed.

  About the developing roller manufactured in Example 1-1 to Comparative Example 4-2, the Re of the region from the end of the resin layer to 8% of the length of the developing roller and the width of 8% of the length in the developing roller longitudinal direction Rc was measured in the central region of the developing roller. At that time, four points were measured in the circumferential direction at the same position in the axial direction. The results are shown in Table 4.

From the results of Table 3, the ratios Re and Rc of the number of Si atoms attributed to SiO ₂ with respect to the total number of Si atoms at the time when Si atoms attributed to Si—O derived from the elastic layer were detected are 0.25 or more. When satisfying 0.80 or less, it was found that both improvement in adhesion of the resin layer and suppression of fogging can be achieved (Example 1-1 to Example 4-4).

  Further, it has been found that the unreacted polysiloxane is contained in the silicone rubber of the elastic layer, and the developing roller of the present invention can be obtained if the corona treatment is performed under certain conditions even if the ratio changes. (Example 1-1 to Example 1-3).

  Furthermore, it was found that when Re and Rc satisfy Re × 0.50 ≦ Rc ≦ Re × 0.90, it is possible to achieve both higher adhesion of the resin layer and suppression of fog at a higher level (Example 2-7). To Example 2-11).

  Further, when the average current density I (A / m) of the entire corona electrode satisfies 7.0 (A / m) ≦ I ≦ 35.0 (A / m), the adhesion of the resin layer is improved and the fog is suppressed. It was found that a developing roller capable of satisfying both of these conditions can be provided (Example 2-1 to Example 2-11).

  Furthermore, when Ie (A / m) and Ic (A / m) satisfy Ic × 1.2 (A / m) ≦ Ie ≦ Ic × 2.0 (A / m), the adhesion of the resin layer is improved. It was found that the suppression of fog and fog can be achieved at a higher level (Example 2-7 to Example 2-11).

  Furthermore, it was found that when the surface roughness Ra of the corona electrode is 1.0 μm or more and 3.0 μm or less, the adhesion of the resin layer can be improved and the suppression of fogging can be achieved at a higher level (Example 3-1 to Example). 3-4).

  Furthermore, when the corona treatment was performed after heating the elastic layer surface to a temperature of 150 ° C. or higher and 220 ° C. or lower in advance, it was found that the adhesion of the resin layer and the suppression of fog could be achieved at a higher level (Example 4-1). To Example 4-4).

  It was found that if Re and Rc do not satisfy 0.25 or more and 0.80 or less, the adhesiveness of the resin layer is reduced or a slight fog is produced as compared with those satisfying that ( Example 5-1 to Example 5-2).

FIG. 2 is a schematic cross-sectional view showing an example of the developing roller of the present invention, (a) parallel to the longitudinal direction and (b) perpendicular to the longitudinal direction. FIG. 3 is a schematic cross-sectional view showing a distribution state of the SiO ₂ portion of the developing roller of the present invention, in which (a) is perpendicular to the longitudinal direction and (b) the elastic layer surface has a diameter of 100 μm. It is a schematic block diagram which shows an example of the corona treatment apparatus concerning this invention. It is a schematic block diagram which shows an example of the corona electrode in the corona treatment apparatus concerning this invention. 1 is a schematic configuration diagram illustrating an example of an electrophotographic image forming apparatus according to the present invention. 1 is a schematic configuration diagram illustrating an example of an electrophotographic process cartridge according to the present invention. It is a figure which shows the area | region which measures the value of R of this invention.

Explanation of symbols

10 developing roller 11 mandrel 12 portion is formed of an elastic layer 13 SiO ₂ (SiO ₂ portion)
DESCRIPTION OF SYMBOLS 14 Resin layer 30 Corona treatment apparatus 31 Chamber 32 Corona ammeter 33 High frequency power supply 34 Gas introduction port 35 Gas exhaust port 36 Support part 37 Rotation drive part 38 Purge port 39 Pulse generator 40 Corona electrode 41 Conductor part 42 Insulator part 500 Electron Photographic image forming apparatus 505 photoconductor 506 toner supply roller 507 toner container 508 toner amount regulating member 509 developing device 510 laser beam 511 charging device 512 cleaning device 513 blade bias power source 514 developing roller bias power source 515 fixing device 516 driving roller 517 transfer roller 518 Transfer bias power supply 519 Tension roller 520 Transfer conveyance belt 521 Drive roller 522 Recording material 523 Paper feed roller 524 Adsorption roller 525 Adsorption bias power supply 526 Immersion Dipping tank 527 Liquid feed pump 528 Stirring tank 529 Lifting device 530 Process cartridge for electrophotography

Claims (10)

A developing roller having a shaft core, an elastic layer formed of silicone rubber provided around the shaft core, and a resin layer covering the elastic layer;
A developing roller, wherein portions formed of SiO ₂ are interspersed between the elastic layer and the resin layer. The developing roller according to claim 1, wherein the maximum length of the portion formed of SiO ₂ observed with a transmission electron microscope is 0.1 μm or more and 10 μm or less. When the composition analysis in the depth direction within the range of 100 μm in diameter was performed by X-ray photoelectron spectroscopy from the surface of the resin layer, all of the Si atoms attributed to Si—O derived from the elastic layer were detected. The developing roller according to claim 1, wherein a ratio R of the number of Si atoms attributed to a portion formed of SiO ₂ with respect to the number of Si atoms is 0.25 or more and 0.80 or less.   When the value of R in the end region of the developing roller is Re and the value of R in the central region of the developing roller is Rc, Re and Rc are Re × 0.50 ≦ Rc ≦ Re The developing roller according to claim 3, wherein × 0.90 is satisfied. A method for producing a developing roller, comprising: a shaft core; an elastic layer formed of silicone rubber provided around the shaft core; and a resin layer covering the elastic layer. A step of corona treatment on the elastic layer with the corona electrode facing the longitudinal direction of the layer to vaporize and decompose unreacted polysiloxane present in the elastic layer to form scattered SiO ₂ A method for producing a developing roller, comprising:   During the corona treatment, the average current density Ie (A / m) in the region from the end of the resin layer to 8% of the length of the developing roller in the longitudinal direction, and the width of 8% of the length in the developing roller longitudinal direction The average current density Ic in the developing roller central region satisfies Ic × 1.2 (A / m) ≦ Ie ≦ Ic × 2.0 (A / m). Method for producing a developing roller.   The method for manufacturing a developing roller according to claim 5 or 6, wherein the surface roughness Ra of the corona electrode is 1.0 µm or more and 3.0 µm or less.   8. The method for producing a developing roller according to claim 5, wherein the elastic layer surface is preliminarily heated to a temperature of 150 ° C. or higher and 220 ° C. or lower to perform corona treatment.   An electrophotographic process cartridge comprising at least a photosensitive member for forming an electrostatic latent image and a developing roller disposed in contact with the photosensitive member, and configured to be detachable from an electrophotographic image forming apparatus. An electrophotographic process cartridge, wherein the developing roller is the developing roller according to claim 1.   5. The developing roller according to claim 1, comprising at least a photosensitive member for forming an electrostatic latent image and a developing roller disposed in contact with the photosensitive member. An image forming apparatus for electrophotography, comprising:

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