JP2010060892A - Electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus which stably provides a high-quality electrophotographic image by including a charging member equipped with a surface layer having a high effect of suppressing adhesion of a low molecular weight component which oozes out from an elastic layer to an electrophotographic photoreceptor and having excellent durability. <P>SOLUTION: The electrophotographic image forming apparatus includes the electrophotographic photoreceptor, the charging member which is arranged in contact with the electrophotographic photoreceptor, and a charging means which applies voltage to the charging member to charge the electrophotographic photoreceptor. The charging member includes a shaft core, the elastic layer and the surface layer covering a surface of the elastic layer. The surface layer contains a silicon oxide film containing a carbon atom chemically bonded to a silicon atom, and the silicon oxide film has specific composition. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a laser printer.

A charging member used in a contact charging method for charging the electrophotographic photosensitive member by applying a voltage to the charging member brought into contact with the electrophotographic photosensitive member is generally used to ensure a nip width with the electrophotographic photosensitive member. Is provided with an elastic layer. However, since the charging member is in direct contact with the electrophotographic photosensitive member, a low molecular component or the like contained in the elastic layer may ooze out over time and may contaminate the surface of the electrophotographic photosensitive member. In order to suppress such contamination, a charging member has been proposed in which a surface layer is provided on the surface of the elastic layer. Patent Document 1 discloses an amorphous carbon film as a coating layer as a charging member satisfying all of the shape maintaining properties, resistance uniformity, releasability, and antifouling properties that are necessary requirements for a contact charging type charging member. And a charging member provided with a silicon carbide (SiC) film.
JP 2006-235045 A

However, the charging member configured to cover the elastic layer with the surface layer made of such an inorganic film has the following problems. That is, the surface layer does not completely follow the elastic deformation of the elastic layer due to repeated use, and a crack may occur. As a result, the low molecular weight component in the elastic layer may adhere to the surface of the electrophotographic photosensitive member from the crack, and the quality of the electrophotographic image may be impaired. Accordingly, in view of the above circumstances, the present inventors have provided a surface layer that satisfies the following requirements in order to further improve the quality of an electrophotographic image in relation to contact charging. We came to realize that the development of charging members is important.
1. The ability to effectively suppress bleed out of low molecular weight components from the elastic layer,
2. Excellent adhesion to the elastic layer, it is difficult to peel off from the elastic layer even by repeated image formation,
3. It must be flexible enough to follow the deformation of the elastic layer and will not easily crack even after repeated image formation.

  Accordingly, an object of the present invention is to provide an electrophotographic image forming apparatus that includes a charging member having a surface layer that satisfies the above requirements 1 to 3 and that can stably provide high-quality electrophotographic images. In the point.

  The inventors of the present invention have made various studies in order to achieve the above object. As a result, it has been found that a silicon oxide film having a specific composition satisfies the above requirements 1 to 3 at a high level. The present invention has been made based on such findings.

That is, the electrophotographic image forming apparatus according to the present invention includes an electrophotographic photoreceptor,
A charging member disposed in contact with the electrophotographic photosensitive member;
An electrophotographic image forming apparatus comprising charging means for applying a voltage to the charging member to charge the electrophotographic photosensitive member,
The charging member comprises a shaft core, an elastic layer, and a surface layer covering the surface of the elastic layer,
The surface layer includes a silicon oxide film containing carbon atoms chemically bonded to silicon atoms,
The silicon oxide film has an abundance ratio (O / Si) of oxygen atoms forming a chemical bond with silicon atoms to silicon atoms of 0.95 or more and 1.80 or less, and has a chemical bond with silicon atoms. The abundance ratio (C / Si) of formed carbon atoms to silicon atoms is 0.10 or more and 1.25 or less.

  According to the present invention, even when a low molecular weight component exudes from the elastic layer by coating the surface of the elastic layer with a silicon oxide film having a specific composition, the surface of the electrophotographic photosensitive member is thereby contaminated. Is effectively suppressed. Thereby, an electrophotographic image forming apparatus capable of obtaining a high-quality electrophotographic image can be obtained.

  Further, since the silicon oxide film has excellent adhesion to the elastic layer and is excellent in flexibility, it is difficult to peel off even after repeated use, and cracking is not likely to occur. As a result, an electrophotographic image forming apparatus capable of stably forming a high-quality electrophotographic image can be provided.

<1> Charging Member FIG. 2 shows a specific configuration of the charging roller as one aspect of the charging member according to the present invention. FIG. 2A is a schematic cross-sectional view in a direction orthogonal to the axis of the charging roller. FIG. 2B is a schematic sectional view in the axial direction.

  The charging roller according to FIG. 2 has a conductive support 1, a conductive elastic layer 2 formed on the outer periphery thereof, and a surface layer 3 covering the outer peripheral surface of the conductive elastic layer 2.

<< Conductive Support 1 >>
The conductive support 1 is a cylinder in which a carbon steel alloy surface is plated with nickel having a thickness of about 5 μm. The following are mentioned as another material which comprises an electroconductive support body. Metals such as iron, aluminum, titanium, copper and nickel; alloys such as stainless steel, duralumin, brass and bronze containing these metals; composite materials in which carbon black and carbon fibers are consolidated with plastic. It is also possible to use a known material that is rigid and exhibits conductivity. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity other than column shape.

<< Conductive Elastic Layer 2 >>
The conductive elastic layer 2 is formed by mixing a conductive agent and a polymer elastic body. Examples of the polymer elastic body include the following. Thermoplastic elastomers such as epichlorohydrin rubber, NBR (nitrile rubber), chloroprene rubber, urethane rubber, silicone rubber, or SBS (styrene / butadiene / styrene / block copolymer) or SEBS (styrene / ethylene butylene / styrene / block copolymer).

  As the polymer elastic body, epichlorohydrin rubber is particularly preferably used. In the epichlorohydrin rubber, the polymer itself has conductivity in the middle resistance region, and can exhibit good conductivity even if the amount of the conductive agent added is small. Moreover, since the variation in electric resistance depending on the position can be reduced, it is suitably used as a polymer elastic body.

  Examples of the epichlorohydrin rubber include the following. Epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer. Of these, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer is particularly preferably used since it exhibits stable conductivity in a medium resistance region. The epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer can control conductivity and workability by arbitrarily adjusting the degree of polymerization and composition ratio.

  The polymer elastic body is mainly composed of epichlorohydrin rubber, but may contain other general rubbers and elastomers as necessary.

  Other common rubbers and elastomers include the following. EPM (ethylene propylene rubber), EPDM (ethylene propylene rubber), NBR (nitrile rubber), chloroprene rubber, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, urethane rubber, silicone rubber. Further, a thermoplastic elastomer such as SBS (styrene / butadiene / styrene block copolymer) or SEBS (styrene / ethylene butylene / styrene block copolymer) may be contained.

  When it contains said general rubber | gum and elastomer, it is preferable that the content is 1-50 mass% with respect to the polymer elastic body whole quantity.

  As the conductive agent, an ionic conductive agent or an electronic conductive agent can be used. For the purpose of reducing unevenness in electrical resistivity of the conductive elastic layer, it is preferable to contain an ionic conductive agent. By uniformly dispersing the ionic conductive agent in the polymer elastic body and making the electrical resistance of the conductive elastic body uniform, uniform charging can be obtained even when the charging roller is used with only DC voltage applied. Can do.

  The ionic conductive agent is not particularly limited as long as it is an ionic conductive agent exhibiting ionic conductivity. Examples of the ionic conductive agent include the following. Inorganic ionic substances such as lithium perchlorate, sodium perchlorate, calcium perchlorate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, trioctylpropylammonium Cationic surfactants such as bromide, modified aliphatic dimethylethylammonium ethosulphate; zwitterionic surfactants such as lauryl betaine, stearyl betaine, dimethylalkyl lauryl betaine; tetraethylammonium perchlorate, tetrabutylammonium perchlorate , Quaternary ammonium perchlorates such as trimethyloctadecyl ammonium perchlorate; Organic acids such as lithium salts of trifluoromethane lithium sulfonate. These can be used alone or in combination of two or more. Among ionic conductive agents, quaternary ammonium perchlorate is particularly preferably used because of its resistance to environmental changes.

The electronic conductive agent is not particularly limited as long as it is an electronic conductive agent exhibiting electronic conductivity. Examples of the electronic conductive agent include the following. Metal-based powders and fibers such as aluminum, palladium, iron, copper and silver; metal oxides such as titanium oxide, tin oxide and zinc oxide; tin oxide, antimony oxide, indium oxide and molybdenum oxide on the surface of suitable particles , Zinc, aluminum, gold, silver, copper, iron, platinum, or rhodium powder deposited by electrolytic treatment, spray coating, mixed shaking; furnace black, thermal black, acetylene black, ketjen black, PAN ( Carbon powder such as polyacrylonitrile) pitch carbon.
As furnace black, the following are mentioned. SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, I-ISAF-HS, HAF-HS, HAF, HAF-LS, T-HS, T-NS, MAF, FEF, GPF, SRF-HS- HM, SRF-LM, ECF, FEF-HS. Thermal black includes FT and MT.

  Moreover, these electrically conductive agents can be used individually or in combination of 2 or more types.

As a compounding amount of the conductive agent to be blended in the conductive elastic layer of the present invention, the volume resistivity of the conductive elastic layer is a medium resistance region (volume resistivity is 1 × 10 ⁴ to 1 × 10 10 in all the following environments. ⁸ Ω · cm) is preferable.
Low temperature and low humidity environment (environment 1; 15 ° C./10% RH);
Normal temperature and humidity environment (environment 2: 23 ° C./50% RH);
High temperature and high humidity environment (environment 3: 30 ° C./80% RH).

  The volume resistivity of the conductive elastic layer can be determined by the following method. That is, after forming into a sheet having a thickness of 1 mm, metal is vapor-deposited on both sides to produce an electrode and a guard electrode. Then, using a microammeter (ADVANTEST R8340A ULTRA HIGH RESISTANCE METER Co., Ltd., Advantest Co., Ltd.), a voltage of 200 V was applied, the current after 30 seconds was measured, and the volume resistivity was calculated from the film thickness and electrode area To do.

  By setting the volume resistivity of the conductive elastic layer in the above numerical range, it is difficult to cause defects in the electrophotographic image even when there is a pinhole in the photosensitive member as the member to be charged.

  In addition, compounding agents such as a plasticizer, a filler, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, a scorch preventing agent, a dispersing agent and a release agent are added to the conductive elastic layer as necessary. You can also.

<<< Molding method >>>
As a method for forming the conductive elastic layer, it is preferable to mix the raw materials of the conductive elastic layer with a hermetic mixer and to form the conductive elastic layer by a known method such as extrusion molding, injection molding, or compression molding. . The conductive elastic layer may be produced by directly forming a conductive elastic layer on a conductive support, or a conductive elastic layer previously formed into a tube shape is coated on the conductive support. You may let them. Note that the surface may be polished and the shape may be adjusted after the production of the conductive elastic layer. The member thus manufactured is referred to as a conductive base layer roller.

  The shape of the conductive elastic layer is preferably formed in a crown shape that is thickest at the center and narrows toward both ends in order to ensure uniform adhesion between the charging roller 5 and the electrophotographic photosensitive member 4. The charging roller 5 generally used is in contact with the electrophotographic photosensitive member 4 by applying a predetermined pressing force to both ends of the support 2a. For this reason, since the pressing force at the central portion is small and the both end portions are large, there is no problem if the straightness of the charging roller 5 is sufficient, but when it is not sufficient, images corresponding to the central portion and both end portions are displayed. Density unevenness may occur. The crown shape is formed to prevent this.

  In order to make the contact nip width uniform when the roller rotates, it is preferable that the difference in outer diameter difference of the conductive support (hereinafter also referred to as “base layer roller”) on which the conductive elastic layer is formed is small.

  A non-contact type laser length measuring device can be used for measuring the outer diameter of the base layer roller. As a non-contact type laser length measuring device, for example, there is a laser scan type dimension / outer diameter measuring device “LS-5000” (trade name) manufactured by Keyence Corporation.

  FIG. 5 shows a measuring method of the outer diameter difference shake using the laser scan type dimension / outer diameter measuring instrument. FIG. 5A is a perspective view of a state in which the base roller 49 and the reference roller 50 to be measured are placed on the measuring instrument, and FIG. 5B is a side view thereof. Reference numeral 51 denotes a laser emitting unit, and 52 denotes a light receiving unit for laser light 53 (shaded portion) emitted from the laser emitting unit 51. First, the reference roller 50 is placed on the measuring instrument so that its axis and the laser beam 53 are orthogonal. Next, the base layer roller 49 as a measurement target is placed on the measuring instrument so as to be parallel to the axis of the reference roller 50. In this state, the width 54 of the laser beam transmitted between the reference roller 50 and the base layer roller 49 is measured. By subtracting the obtained measurement value from the distance between the central axis of the base layer roller 49 and the surface of the reference roller 50, the radius of one measurement cross section of the base layer roller 49 is obtained. By rotating the base roller 49 by 1 ° and performing the same operation as described above, the radius of one round of the base roller 49 in one measurement section is obtained. The difference between the maximum value and the minimum value of the obtained radius values is the deflection of the radius in the measurement cross section. Next, the base layer roller 49 and the measuring device are moved by a predetermined amount in the direction of the arrow 55, 1 cm in the embodiment of the present invention, and the radius of one round of the base layer roller 49 in the other measurement cross section is set. Measure and calculate the runout of the radius in the other measurement cross section. This operation is repeated to calculate the deflection of the radius in a plurality of measurement cross sections in the direction along the axis of the base layer roller 49. In the present invention, the radial runout in the measurement cross section where the radial runout is the largest is defined as the outer diameter runout of the base layer roller.

  The diameter of the base layer roller is measured as the width at which the laser is blocked by the base layer roller 49. Then, each time the base layer roller is rotated by 1 °, the diameter of the base layer roller is measured, and the diameter of one round of the base layer roller 49 in one measurement cross section is obtained. The average value of the maximum value and the minimum value of the measured values obtained is taken as the diameter (average diameter) of the base layer roller in the measurement cross section. In the case of a straight columnar or cylindrical base layer roller, the base layer roller and the measuring device are moved relative to each other by a predetermined amount, in the embodiment according to the present invention, by 1 cm, and the average diameter in other measurement cross sections is obtained. And the average value of the average diameter in each measurement cross section is regarded as the diameter of the base layer roller.

  The crown amount of the base layer roller having a crown shape is such that, in the case of the base layer roller having an axial direction of about 250 mm, the average diameter D1 of the central portion of the base layer roller in the axial direction and the average diameter of the portion 90 mm from the axial direction central portion. A difference {D1− (D2 + D3) / 2} between two values of D2 and D3 is defined as a crown amount.

  In the case of a straight cylindrical or columnar base layer roller, a preferable value of the outer diameter differential deflection of the base layer roller is 0.5% or less, more preferably 0.25% or less of the diameter of the base layer roller. For example, when the diameter of the base layer roller is about 12 mm, the value of the outer diameter differential deflection is specifically preferably 60 μm or less, more preferably 30 μm or less.

  The value of the crown amount is determined so that the width of the nip formed between the charging roller and the electrophotographic photosensitive member is uniform. Preferably it is 5.0% or less of the diameter of the base layer roller. Specifically, when the diameter is about 12 mm, 600 μm or less is preferable.

  The hardness of the conductive elastic layer is micro hardness (MD-1 hardness), preferably 30 ° to 70 °, more preferably 40 ° C. to 60 °. By setting the micro hardness within the above range, a sufficient nip width between the charging member and the photosensitive member can be obtained, so that more stable charging performance can be exhibited. In addition, "micro hardness (MD-1 hardness)" is the hardness of the charging member measured using Asker micro rubber hardness meter MD-1 type type-A (made by Kobunshi Keiki Co., Ltd.). The measurement condition is a value obtained by measuring the hardness meter in a 10 N peak hold mode with respect to a charging member left for 12 hours or more in an environment of normal temperature and normal humidity (23 ° C./50% RH).

  For the purpose of reducing the micro hardness (MD-1 type-A), a plasticizer may be blended in the conductive elastic layer. The blending amount is preferably 1 part by mass to 30 parts by mass, and more preferably 3 parts by mass to 20 parts by mass. As the plasticizer, it is preferable to use a polymer type. The number average molecular weight of the polymer plasticizer is preferably 2000 or more, more preferably 4000 or more. By setting it within this range, the low molecular weight component does not exude excessively from the elastic layer.

  The low molecular weight component and the soluble component contained in the conductive elastic layer can be quantified using a Soxhlet extractor. Specifically, using a Soxhlet extractor, the conductive elastic layer is refluxed for 20 hours using a solvent such as tetrahydrofuran (THF) as a test solvent. The mass reduced by the conductive elastic layer due to this reflux can be used as the Soxhlet extract amount and used as an indicator of low molecular weight components and soluble components. The amount of Soxhlet extracted from the conductive elastic layer is preferably 10 wt% or less.

  In order to reduce the extraction amount from the conductive elastic layer, it is preferable to reduce the blending amount of an additive such as a plasticizer as much as possible. As the plasticizer to be used, the above polymer type is preferably used. The polymer elastic body forming the conductive elastic layer is preferably a vulcanized / crosslinked rubber composition rather than a thermoplastic resin.

  The conductive elastic layer is bonded to the conductive support through an adhesive as necessary. In this case, the adhesive is preferably conductive. In order to make it conductive, a known conductive agent can be used as the adhesive.

  Examples of the binder of the adhesive include a thermosetting resin or a resin such as a thermoplastic resin. Known adhesives such as urethane, acrylic, polyester, polyether and epoxy can be used.

  What was mentioned above can be used as a electrically conductive agent for providing electroconductivity to an adhesive agent. The conductive agents can be used alone or in combination of two or more.

  After forming a conductive elastic layer on a conductive support and producing a conductive base layer roller, an outermost layer 3 is provided as a coating layer.

<< surface layer >>
The surface layer 3 has a silicon oxide film containing carbon atoms chemically bonded to silicon atoms (hereinafter sometimes referred to as “SiOx film”). That is, the SiOx film constituting the surface layer 3 has Si—O and Si—C chemical bonds. The abundance ratio (O / Si) of oxygen atoms chemically bonded to silicon atoms to silicon atoms is 0.95 or more and 1.80 or less. Further, the abundance ratio (C / Si) of carbon atoms forming chemical bonds with silicon atoms to silicon atoms is 0.10 or more and 1.25 or less.

  The abundance ratio O / Si is more preferably 1.30 or more and 1.80 or less. By setting the abundance ratio O / Si within the above numerical range, even if the state of being in direct contact with the electrophotographic photosensitive member is maintained for a long time, the low molecular weight component oozing out from the elastic layer can be transmitted. It can be suppressed very effectively. In addition, since the SiOx film itself does not become too hard, cracks are hardly generated even after repeated use.

  The abundance ratio C / Si is more preferably 0.10 or more and 0.70 or less. When the abundance ratio C / Si is within the above numerical range, sufficient adhesion between the SiOx film and the elastic layer is ensured. In addition, the releasability and water repellency of the surface of the SiOx film are also good, and when used as a charging roller, dirt such as external additives and paper powder hardly adheres. Further, even with a simple regeneration method, the surface dirt can be sufficiently removed.

  The abundance ratio of each element in the outermost layer is determined as follows.

  Using an X-ray photoelectron spectrometer “Quantum 2000” (trade name, manufactured by ULVAC-PHI Co., Ltd.), the surface of the outermost layer 3 of the charging roller is Si 2p orbit and O and C 1s orbits with the X-ray source being AlKα. The peak due to the binding energy is measured. The abundance ratio of each atom is calculated from each peak, and O / Si and C / Si are obtained from the obtained abundance ratio. In addition, since the variation in the position of the value of O / Si and C / Si of the outermost layer according to the present invention formed by the method described later can hardly occur, the measurement location may be one location of the outermost layer.

Further, the presence of a chemical bond of SiOx can be confirmed using a Fourier transform infrared spectroscopic analysis (FT-IR) apparatus “SpectrumOne” (trade name, manufactured by PerkinElmer Japan Co., Ltd.). That, Si-O vibrational peak ^{(450 cm} -1), by the presence of Si-C stretching peak (800-820cm ^-1), it is possible to confirm the presence of chemical bonds Si-O and Si-C.

  Examples of the method for forming the SiOx film on the conductive elastic layer in the present invention include the following.

  Wet coating methods such as dip coating, spray coating, roll coating, ring coating; physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, ion plating; plasma CVD, thermal CVD, laser CVD Chemical vapor deposition (CVD) method.

  Among these, the plasma CVD method particularly takes into consideration the adhesion between the conductive elastic layer and the outermost layer (silicon oxide film containing carbon), the processing time and temperature, the simplicity of the apparatus, and the uniformity of the outermost layer to be obtained. Is more preferable.

  Below, an example of the formation method of the SiOx film | membrane by plasma CVD method is shown.

  FIG. 4 is a schematic view of an apparatus for forming a SiOx film by this plasma CVD method.

  This apparatus includes a vacuum chamber 41, a flat plate electrode 42, a raw material gas cylinder and a raw material liquid tank 43, a raw material supply means 44, a gas exhaust means 45 in the chamber, a high frequency supply power supply 46 for supplying a high frequency, and a base layer roller 48. The motor 47 is configured to rotate the motor.

  Using the apparatus shown in FIG. 4, a charging roller having a SiOx film as the outermost layer can be manufactured by the following procedures (1) to (4).

Procedure (1)
A base layer roller 48 having a conductive elastic layer formed on a shaft core is installed between the flat plate electrodes 42, and the motor 47 is driven to rotate in the circumferential direction so that the obtained SiOx film is uniform.

Procedure (2)
The inside of the vacuum chamber 41 is evacuated by the exhaust means.

Procedure (3)
A source gas is introduced from a source gas inlet, a high frequency power is supplied to the flat plate electrode 42 by a high frequency power supply 46, plasma is generated, and film formation is performed.

Procedure (4)
After a predetermined time has elapsed, the supply of source gas and high-frequency power is stopped, air or nitrogen is introduced (leaked) into the vacuum chamber 41 to atmospheric pressure, and the base layer roller 48 is taken out.

  The charging roller having the SiOx film can be manufactured by the procedure as described above. In addition, as long as the base layer roller 48 processed by plasma CVD can be placed in a uniform plasma atmosphere, a large number of rollers may be processed simultaneously.

  Here, as a raw material gas, a gaseous or gasified organosilicon compound is usually introduced together with a hydrocarbon compound, if necessary, in the presence or absence of a gas such as an inert gas or an oxidizing gas.

  Examples of the hydrocarbon compound include toluene, xylene, methane, ethane, propane, and acetylene.

  Examples of the organosilicon compound include the following.

  1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, hexamethyldisilazane, vinyltrimethylsilane, methyltrimethoxysilane, hexamethyldisilane, methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, diethylsilane , Propylsilane, phenylsilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, octamethylcyclotetrasiloxane.

  From the viewpoint of handling, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, and tetramethylsilane are preferable.

  The silane source is not limited to the organosilicon compound, and silane, aminosilane, and silazane can also be used.

  If the organosilicon compound or the like is in a gaseous state, it is used as it is, and if it is liquid at room temperature, it is heated and vaporized and transported with an inert gas, or is bubbled with an inert gas and transported. Furthermore, in the case of a solid at room temperature, it is heated and vaporized, and is transported by an inert gas. Further, vaporization may be promoted in a reduced pressure state of the raw material.

When the raw material organosilicon compound is an oxygen-containing compound, the SiOx film can be deposited without oxygen. Also, an oxidizing gas such as oxygen or an oxidizing power gas (N ₂ O, CO _2, etc.) is introduced into the vacuum chamber together with or in addition to the source gas. Examples of the inert gas that can be used above include helium, argon, and nitrogen.

  The abundance ratio of silicon atoms, oxygen atoms chemically bonded to silicon atoms, and carbon atoms chemically bonded to silicon atoms in the SiOx film should be controlled by the mixing ratio of the raw material gas to be introduced, the high frequency power supplied, etc. Is possible.

  Specifically, for example, the O / Si value can be increased by increasing the ratio of oxygen gas in the above-described compounding ratio of the organosilicon compound and oxygen gas. The value of C / Si can be increased by reducing the ratio of oxygen gas.

  Moreover, the value of O / Si and C / Si can be reduced by increasing the high frequency power. Furthermore, by using the above-described hydrocarbon compound in combination, the values of O / Si and C / Si can be increased according to the amount of the hydrocarbon compound used.

  The thickness of the SiOx film thus formed is preferably 10 nm or more and 2000 nm or less, more preferably 20 nm or more and 1000 nm or less. By making the film thickness within the above numerical range, the film can be sufficiently used against wear associated with long-term use.

  The film thickness of the formed SiOx film was measured at three locations at equal intervals from the end in the longitudinal direction of the charging roller using a thin film measuring device “F20-EXR” (trade name, manufactured by FILMETRICS) and in the circumferential direction. A total of nine places at three equal intervals were measured and the average value of the obtained values.

  The charging roller is useful as a charging roller of a charging device of an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and as a charging roller of a charging device of a process cartridge in an image forming apparatus of a process cartridge type.

<Charging device>
An example of the charging device of the present invention is shown in FIG. For example, in the charging roller 34, both ends of the conductive support (core metal) 31 are respectively supported by bearings 35, and both the bearings are urged by a spring 36 toward a photosensitive drum (not shown). Thus, the photosensitive drum is brought into pressure contact. The bearing 35 is guided by a frame body 37. Further, a voltage is applied to the charging roller by the power source 19 via the contact point 38, the spring 36, the bearing 35, and the cored bar 31. Note that a lubricant such as grease may be interposed between the sliding portions of the metal core and the bearing for the purpose of imparting lubricity. Further, as shown in FIG. 3C, a flexible film member having one end fixed as a cleaning member 39 on the surface of the charging roller can be arranged in surface contact. By sliding the film-like cleaning member 39 and the roller, dirt such as toner and external additives attached to the surface of the charging roller can be cleaned and removed.

<Electrophotographic image forming apparatus>
An example of an electrophotographic image forming apparatus having a charging device equipped with a charging roller according to the present invention is shown in FIG.

  The photosensitive drum 4 serving as an image carrier is primarily charged by the charging roller 5 while rotating in the direction of the arrow, and then exposed to exposure 11 by an exposure unit to form an electrostatic latent image.

  Further, the toner is supplied to the surface of the developing roller 6 as developing means by the toner supply roller 14, and then the toner is thinned on the developing roller 6 by the elastic regulation blade 13. Further, when the toner in the thin layer comes into contact with the surface of the photosensitive drum 4, the electrostatic latent image is developed and a visualized toner image is formed.

  The developed toner image is transferred from the photosensitive drum 4 to the print medium 7 as the transfer target member at the transfer portion between the transfer roller 8 as the transfer member and the photosensitive drum 4, and then heated by the fixing portion 9. The image is fixed by pressure and becomes a permanent image. The latent image remaining on the photosensitive drum 4 is exposed by the pre-charging exposure device 12, and the potential of the photosensitive drum 4 returns to the ground potential. The untransferred toner that has not been transferred is collected by the cleaning blade 10.

  Voltages are respectively applied to the developing roller 6, the charging roller 5, and the transfer roller 8 from power sources 18, 19, and 20 of the image forming apparatus.

  Here, to the charging roller 5 of the present invention, a DC electric field alone or an oscillating electric field in which an AC voltage is superimposed on the DC voltage is applied from the power source 19.

  When only a DC voltage is applied (hereinafter referred to as a DC charging method), the absolute value of the applied DC voltage is the sum of the discharge start voltage of air and the primary charging potential of the surface of the member to be charged (photosensitive member surface). It is preferable to do. Usually, the discharge start voltage of air is about 500 to 700 V, and the primary charging potential of the photoreceptor surface is about 300 to 800 V. Therefore, the specific primary charging voltage is preferably 800 to 1500 V.

  When applying an oscillating electric field in which an AC voltage is superimposed on a DC voltage (hereinafter referred to as an AC charging method), for example, an AC voltage having a DC voltage and a peak-to-peak voltage that is twice or more the air discharge start voltage. It is preferable to apply a superimposed voltage. The absolute value of the DC voltage is preferably set to a primary charging potential (about 300 to 800 V) on the surface of the photoreceptor.

  In the case of a color image forming apparatus, a photosensitive drum, a developing roller, a transfer roller, a charging roller, an elastic regulating blade, an exposure, a toner container, and the like are unitized and each has four colors (black, cyan, magenta, yellow). ) Can be prepared and arranged in series.

  EXAMPLES Hereinafter, an Example is shown and this invention is demonstrated more concretely.

  In addition to the reagents described below, those having a purity of 99.5% or more were used unless otherwise specified.

Production Example 1 Production of Base Layer Roller 1 The following materials were mixed for 10 minutes with a closed mixer.
・ Acrylonitrile butadiene rubber (NBR)
(Product name: Nipol DN-219; manufactured by Nippon Zeon Co., Ltd.): 100 parts by mass,
-Sebacic acid-based polyester as a plasticizer (trade name: Polysizer P202; manufactured by Dainippon Ink & Chemicals, Inc., number average molecular weight 8000): 7 parts by mass,
・ Stearic acid (trade name: MXST; manufactured by Miyoshi Oil & Fat Co., Ltd.): 1 part by mass as a vulcanization aid
-Zinc oxide (trade name: Zinc oxide 2 types; manufactured by Sakai Chemical Industry Co., Ltd.): 5 parts by mass
Carbon black (trade name: Talker Black # 7360SB; manufactured by Tokai Carbon Co., Ltd.): 50 parts by mass.

  To this mixture, 1 part by mass of sulfur as a vulcanizing agent and 3 parts by mass of tetrabenzylthiuram disulfide (TBZTD trade name: Perkasit TBZTD; manufactured by Flexis Co., Ltd.) as a vulcanizing auxiliary are added and further mixed with an open roll, and NBR is added. A kneaded product was obtained. The NBR kneaded product is extruded into a cylindrical shape having an outer diameter of 13.5 mm and an inner diameter of 5.5 mm using an extruder, cut into a length of 250 mm, and steam steam at a temperature of 160 ° C. using a steam vulcanizer. In this, primary vulcanization was carried out for 40 minutes to obtain a conductive elastic layer rubber primary vulcanization tube.

  Next, a thermosetting adhesive for the purpose of bonding metal and rubber to the axially central portion 231 mm of the cylindrical surface of a cylindrical conductive support (steel, surface is nickel-plated) having a diameter of 6 mm and a length of 256 mm Was applied and dried at 80 ° C. for 10 minutes. This conductive support was inserted into the conductive elastic layer rubber primary vulcanization tube, and then heat-bonded for 1 hour at 150 ° C. in an electric oven. Next, both ends of the rubber part are cut off, the length of the rubber part is set to 232 mm, and the rubber part is polished with a rotating grindstone, and the 90 mm position on both sides from the central part is 8.40 mm in diameter and the central part is 8.50 mm in diameter. A base layer roller 1-1 having a crown shape was prepared. Further, in the same manner, a base layer roller 1-2 having a crown shape with a diameter of 12.00 mm at both sides 90 mm from the center and a diameter of 12.20 mm at the center was created.

  The obtained base layer roller 1-1 was measured for micro hardness (MD-1 type-A), surface ten-point average roughness Rzjis, and outer diameter differential deflection. The analysis results are shown in Table 1. Moreover, about the electroconductive elastic layer, the Soxhlet extraction amount at the time of refluxing for 20 hours with tetrahydrofuran (THF) was measured. The analysis results are shown in Table 1.

Production Example 2 Production of Base Layer Roller 2 The following materials were kneaded for 10 minutes with a closed mixer.
Epichlorohydrin rubber (Epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer, trade name: Epion 301; manufactured by Daiso Corporation): 100 parts by mass,
Calcium carbonate as a filler (trade name: Super # 1700; manufactured by Maruo Calcium Co., Ltd.): 50 parts by mass
-Zinc stearate as a vulcanization aid (trade name: Zinc stearate N; Dannan Chemical Co., Ltd.): 1 part by mass
-Zinc oxide: 5 parts by mass,
-Carbon black (FEF) as a reinforcing material for improving abrasiveness: 5 parts by mass,
As a plasticizer, sebacic acid-based polyester (number average molecular weight 8000): 5 parts by mass
-Perchloric acid quaternary ammonium salt of the following formula: 2 parts by mass,

-2-mercaptobenzimidazole as an anti-aging agent: 1 part by mass.

  Then, 1 part by mass and 0.5 part by mass of 2-benzothiazolyl disulfide and tetramethylthiuram monosulfide as vulcanization accelerators and 1 part by mass of sulfur as a vulcanizing agent were added, and the mixture was opened for 5 minutes. The resulting mixture was kneaded to obtain an epichlorohydrin rubber kneaded product. Base layer rollers 2-1 and 2-2 were obtained in the same manner as in Production Example 1 except that the above epichlorohydrin rubber kneaded material was used. Table 1 shows the analysis results of the base layer roller 2-1.

Production Example 3 Production of Base Layer Roller 3 The following materials were mixed and melt-extruded with a twin screw extruder having a diameter of 30 mmL / D32 to obtain a pellet-shaped resin composition.
-Thermoplastic polyurethane-based elastomer (trade name: Kuramiron U8145; manufactured by Kuraray Co., Ltd.): 100 parts by mass,
Carbon black as a conductive agent (trade name: Talker Black # 7360SB; manufactured by Tokai Carbon Co., Ltd.): 45 parts by mass.

  This resin composition was subjected to crosshead extrusion molding to form a resin layer on the peripheral surface of the shaft core (diameter 6 mm, length 256 mm). Both end portions of this resin layer were cut off, and the resin layer portion was further polished with a rotating grindstone to form base layer rollers 3-1 and 3-2 having the same crown shape as in Production Example 1. Table 1 shows the analysis result of the base layer roller 3-1.

Production Example 4 Production of Base Layer Roller 4 The following materials were mixed and melt-extruded with a twin screw extruder having a diameter of 30 mmL / D32 to obtain a pellet-shaped resin composition. This resin composition was subjected to cross head extrusion to form a resin layer on a shaft core (diameter 6 mm, length 256 mm). Both end portions of this resin layer were cut off, and the resin layer portion was further polished with a rotating grindstone to obtain base layer rollers 4-1 and 4-2 having the same crown shape as in Production Example 1. Table 1 shows the analysis results of the base layer roller 4-1.
Polyolefin elastomer (trade name: Santoprene 8211-25; manufactured by AES Japan): 100 parts by mass,
Carbon black as a conductive agent (trade name: Talker Black # 4500; manufactured by Tokai Carbon Co., Ltd.): 50 parts by mass.

(Production Example 5) Production of base layer roller 5 The following materials were kneaded for 10 minutes with a closed mixer.
Epichlorohydrin rubber (Epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer, trade name: Epion 301; manufactured by Daiso Corporation): 70 parts by mass,
・ Acrylonitrile butadiene rubber (NBR)
(Product name: Nipol DN-219; manufactured by Nippon Zeon Co., Ltd.): 30 parts by mass,
-Calcium carbonate as filler: 50 parts by weight,
-Zinc stearate as a vulcanization aid: 1 part by mass,
-Zinc oxide: 5 parts by mass,
-Carbon black (FEF) as a reinforcing material for improving abrasiveness: 5 parts by mass,
As a plasticizer, sebacic acid-based polyester (number average molecular weight 8000): 5 parts by mass
-Perchloric acid quaternary ammonium salt of the following formula: 2 parts by mass,

-2-mercaptobenzimidazole as an anti-aging agent: 1 part by mass.

  Next, 1 part by mass of TS (tetramethylthiuram monosulfide) as a vulcanization accelerator and 3 parts by mass of sulfur as a vulcanizing agent were added and kneaded with an open roll for 5 minutes to obtain an epichlorohydrin rubber / NBR blend kneaded product. . Base layer rollers 5-1 and 5-2 were obtained in the same manner as in Production Example 1 except that the above epichlorohydrin rubber / NBR blend kneaded material was used. Table 1 shows the analysis result of the base layer roller 5-1.

Production Example 6 Production of Base Layer Roller 6 The following materials were mixed for 10 minutes with a closed mixer.
・ Acrylonitrile butadiene rubber (NBR)
(Product name: Nipol DN-219; manufactured by Nippon Zeon Co., Ltd.): 100 parts by weight,
-Sebacic acid-based polyester as a plasticizer (number average molecular weight 8000): 5 parts by mass
・ Stearic acid as a vulcanization aid: 1 part by mass,
-Zinc oxide: 5 parts by mass,
Carbon black as a conductive agent (trade name: Talker Black # 7360SB; manufactured by Tokai Carbon Co., Ltd.): 50 parts by mass.

  Next, 1 part by mass of sulfur as a vulcanizing agent and 3 parts by mass of tetrabenzylthiuram disulfide (TBZTD) as a vulcanization auxiliary were added and further mixed with an open roll to obtain rubber kneaded material A.

Further, the following materials were kneaded for 10 minutes with a closed mixer.
Epichlorohydrin rubber (epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer): 100 parts by mass,
-Calcium carbonate as filler: 50 parts by weight,
-Zinc stearate as a vulcanization aid: 1 part by mass,
-Zinc oxide: 5 parts by mass,
-Carbon black (FEF) as a reinforcing material for improving abrasiveness: 5 parts by mass,
As a plasticizer, sebacic acid-based polyester (number average molecular weight 8000): 5 parts by mass
-2-mercaptobenzimidazole as an anti-aging agent: 1 part by mass.

  Further, 1 part by mass and 0.5 part by mass of 2-benzothiazolyl disulfide) and tetramethylthiuram monosulfide were added as a vulcanization accelerator and 1 part by mass of sulfur as a vulcanizing agent, respectively. And it knead | mixed for 5 minutes with the open roll, and the rubber kneaded material B was obtained.

  The rubber kneaded material A and the rubber kneaded material B were extruded using a two-layer extruder, and a cylindrical two-layer tube was extruded so that the rubber kneaded material A was inside and the rubber kneaded material B was outside. A cylindrical double-layer tube having an outer diameter of 13.5 mm and an inner diameter of 5.5 mm was obtained.

  Base layer rollers 6-1 and 6-2 were obtained in the same manner as in Production Example 1 except that the above two-layer tube was used.

  The hydrin rubber layer (outer layer) at the center of the base layer roller 6-1 was 0.50 mm thick, and the NBR layer (inner layer) was 0.75 mm thick. The hydrin rubber layer (outer layer) at the center of the base layer roller 6-2 had a thickness of 0.55 mm, and the NBR layer (inner layer) had a thickness of 2.55 mm. Table 1 shows the analysis result of the base layer roller 6-1.

Production Example 7 Production of Base Layer Roller 7 In Production Example 1, a base layer roller was prepared in the same manner as in Production Example 1 except that the composition of sebacic acid-based polyester (number average molecular weight 8000) was omitted (0 part by mass) as the plasticizer. 7-1 and 7-2 were prepared.

  Table 1 shows the analysis results of the base layer roller 7-1.

Production Example 8 Production of Base Layer Roller 8 In Production Example 1, the same procedure as in Production Example 1 except that the composition of sebacic acid-based polyester (number average molecular weight 8000) as a plasticizer was changed to 12 parts by mass. And 8-2.

  Table 1 shows the analysis results of the base layer roller 8-1.

Production Example 9 Production of Base Layer Roller 9 In Production Example 1, 10 parts by mass of sebacic acid polyester (molecular weight 8000) as a plasticizer and 2 parts by mass of adipic acid ester compound (number average molecular weight 500) were used. Except for the above, base layer rollers 9-1 and 9-2 were prepared in the same manner as in Production Example 1. Table 1 shows the analysis results of the base layer roller 9-1.

(Production Example 10) Production of Base Layer Roller 10 In Production Example 1, the same procedure as in Production Example 1 except that the compound of adipic acid ester (number average molecular weight 500) was 12 parts by mass as a plasticizer. 10-2 was created. Table 1 shows the analysis results of the base layer roller 10-1.

Production Example 11 Production of Base Layer Roller 11 The following materials were mixed and defoamed using a planetary mixer to obtain a base material for liquid silicone rubber.
Dimethylpolysiloxane having vinyl groups at both ends (vinyl group content 0.15% by mass): 100 parts by mass
Quartz powder as a filler (trade name: Min-USil; manufactured by Pennsylvania Glass Sand): 7 parts by mass
Carbon black (trade name: Denka Black; manufactured by Denki Kagaku Kogyo Co., Ltd.): 10 parts by mass.

  To this base material, 0.5 part by mass of a complex of chloroplatinic acid and divinyltetramethyldisiloxane was blended as a curing catalyst to prepare a solution A. Also, 1.5 parts by mass of a dimethylsiloxane-methylhydrogensiloxane copolymer having both Si-H groups at both ends (H content of 0.30% bonded to Si atoms) is blended with the base material, did.

  On the other hand, a cylindrical mold (for Φ8.5) having a cylindrical shaft core with a diameter of 6 mm and a length of 256 mm arranged on the surface was prepared. Into this mold, a mixture of the liquid A and liquid B mixed at a mass ratio of 1: 1 by a static mixer is injected, cured at a temperature of 130 ° C. for 20 minutes, and further post-cured at a temperature of 200 ° C. for 4 hours. The base layer roller 11-1 was obtained. The obtained base layer roller 11-1 had a crown shape with a diameter of 8.47 mm at both sides 90 mm from the center and a diameter of 8.50 mm at the center. The base layer roller 11-1 was not polished on the surface.

  Further, in the same manner using a cylindrical mold (for Φ12.0), a base layer roller 11-2 having a crown shape with a diameter of 12.00 mm at both sides 90 mm from the center and a diameter of 12.05 mm at the center. It was created. Table 1 shows the analysis results of the base layer roller 11-1.

<Example 1>
The base layer roller 2-1 was installed in the plasma CVD apparatus shown in FIG. Thereafter, the vacuum chamber was depressurized to 1 Pa using a vacuum pump. Thereafter, a mixed gas of 1.0 sccm of hexamethyldisiloxane vapor, 1.5 sccm of oxygen and 22.5 sccm of argon gas was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was set to 25.3 Pa. After the pressure became constant, power with a frequency of 13.56 MHz and 120 W was supplied from a high-frequency power source to the plate electrodes, and plasma was generated between the electrodes. The base layer roller 2-1 installed in the vacuum chamber was rotated at 24 rpm and treated for 120 seconds. After the treatment, the power supply was stopped, the raw material gas remaining in the vacuum chamber was exhausted, and air was introduced into the vacuum chamber until atmospheric pressure was reached. Thereafter, the charging roller on which the surface layer was formed was taken out.

  The abundance ratio O / Si and abundance ratio C / Si were determined on the surface of the obtained charging roller with an X-ray photoelectron spectrometer.

  Moreover, the film thickness of the surface layer of the charging roller was measured using a thin film measuring apparatus (trade name: F20-EXR; manufactured by FILMETRICS). In addition, the measurement was performed at a total of nine places including three places equally divided in the longitudinal direction of the charging roller and three places equally divided in the circumferential direction, and the average value of the obtained values was taken as the film thickness. The analysis results are shown in Table 2.

<Example 2>
The base layer roller 1-1 was used, and the plasma CVD processing time for forming the surface layer was 90 seconds. Otherwise, a charging roller was prepared in the same manner as in Example 1. Table 2 shows the analysis results of this charging roller.

<Example 3>
A charging roller was obtained in the same manner as in Example 2 except that the time for the plasma CVD treatment was 8 seconds. Table 2 shows the analysis results of this charging roller.

<Example 4>
A charging roller was obtained in the same manner as in Example 2 except that the time of the plasma CVD process was changed to 5 seconds. Table 2 shows the analysis results of this charging roller.

<Example 5>
A charging roller was obtained in the same manner as in Example 2 except that the plasma CVD treatment time was 60 seconds. Table 2 shows the analysis results of this charging roller.

<Example 6>
A charging roller was obtained in the same manner as in Example 2 except that the plasma CVD treatment time was 150 seconds. Table 2 shows the analysis results of this charging roller.

<Example 7>
In the formation of the surface layer, the composition of the source gas was hexamethyldisiloxane vapor 1.0 sccm, oxygen 2.5 sccm, and argon gas 21.5 sccm. The plasma CVD treatment time was 30 seconds. Otherwise, a charging roller was obtained in the same manner as in Example 2. Table 2 shows the analysis results of this charging roller.

<Example 8>
In forming the surface layer, the composition of the source gas was 1.0 sccm of hexamethyldisiloxane vapor, 0.5 sccm of oxygen, and 23.5 sccm of argon gas. The plasma CVD process time was 360 seconds. Otherwise, a charging roller was obtained in the same manner as in Example 2. Table 2 shows the analysis results of this charging roller.

<Example 9>
In the formation of the surface layer, a charging roller was obtained in the same manner as in Example 8 except that the time of plasma CVD treatment was set to 100 seconds. Table 2 shows the analysis results of this charging roller.

<Example 10>
In the formation of the surface layer, a charging roller was obtained in the same manner as in Example 8 except that the time of plasma CVD treatment was set to 60 seconds. Table 2 shows the analysis results of this charging roller.

<Example 11>
In the formation of the surface layer, a charging roller was obtained in the same manner as in Example 1 except that the plasma CVD treatment time was 240 seconds. Table 2 shows the analysis results of this charging roller.

<Example 12>
In the formation of the surface layer, a charging roller was obtained in the same manner as in Example 2 except that the time of plasma CVD treatment was 12 seconds. Table 2 shows the analysis results of this charging roller.

<Example 13>
A charging roller was obtained in the same manner as in Example 2 except that the base layer roller 3-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 14>
A charging roller was obtained in the same manner as in Example 2 except that the base layer roller 4-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 15>
A charging roller was obtained in the same manner as in Example 2 except that the base layer roller 5-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 16>
A charging roller was obtained in the same manner as in Example 2 except that the base layer roller 6-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 17>
A charging roller was obtained in the same manner as in Example 1 except that the base layer roller 7-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 18>
A charging roller was obtained in the same manner as in Example 1 except that the base layer roller 8-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 19>
A charging roller was obtained in the same manner as in Example 1 except that the base layer roller 9-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 20>
A charging roller was obtained in the same manner as in Example 1 except that the base layer roller 10-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 21>
A charging roller was obtained in the same manner as in Example 1 except that the base layer roller 11-1 was used. Table 2 shows the analysis results of this charging roller.

<Example 22>
In forming the surface layer, the raw material gas composition was changed to tetrascylsilane vapor 1.0 sccm, oxygen 0.5 sccm, and argon gas 22.5 sccm, and the plasma CVD treatment time was 180 seconds. Otherwise, a charging roller was obtained in the same manner as in Example 2. Table 2 shows the analysis results of this charging roller.

<Example 23>
In the formation of the surface layer, the charging roller was set in the same manner as in Example 1 except that the raw material gas composition was changed to 1.0 sccm of hexamethyldisiloxane vapor and 21.5 sccm of argon gas, and the time of plasma CVD treatment was set to 90 seconds. Obtained. Table 2 shows the analysis results of this charging roller.

<Example 24>
In forming the surface layer of Example 23, 5 sccm of hexamethylsiloxane vapor was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was set to 3 Pa. Further, 200 W of electric power was supplied to the parallel plate electrodes from a high frequency power source. Further, a charging roller was obtained in the same manner as in Example 23 except that the plasma CVD treatment time was set to 360 seconds. Table 2 shows the analysis results of this charging roller.

<Example 25>
In the formation of the surface layer in Example 24, a mixed gas of 9 sccm of hexamethyldisiloxane vapor and 16 sccm of toluene vapor was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was set to 6 Pa. Further, a charging roller was obtained in the same manner as in Example 24 except that the time of plasma CVD treatment was set to 300 seconds. Table 2 shows the analysis results of this charging roller.

<Example 26>
In the formation of the surface layer of Example 8, a charging roller was obtained in the same manner as in Example 8 except that the plasma CVD treatment time was 240 seconds. Table 2 shows the analysis results of this charging roller.

<Example 27>
In the formation of the surface layer of Example 25, a mixed gas of 9 sccm of hexamethyldisiloxane vapor and 10 sccm of toluene vapor was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was 6 Pa. Further, a charging roller was obtained in the same manner as in Example 25 except that the plasma CVD treatment time was 240 seconds. Table 2 shows the analysis results of this charging roller.

<Comparative Example 1>
In the formation of the surface layer of Example 21, the raw material gas composition was changed to tetramethylsilane vapor 1.0 sccm, oxygen 2.5 sccm, and argon gas 21.5 sccm. Further, the plasma CVD treatment time was set to 120 seconds. Otherwise, a charging roller was obtained in the same manner as in Example 21. Table 2 shows the analysis results of this charging roller.

<Comparative example 2>
In the formation of the surface layer of Example 21, 30 sccm of hexamethyldisiloxane vapor was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was 6 Pa. Further, 200 W of electric power was supplied from a high frequency power source. Further, a charging roller was obtained in the same manner as in Example 21 except that the plasma CVD treatment time was 300 seconds. Table 2 shows the analysis results of this charging roller.

<Comparative Example 3>
A mixed solution containing, as a main solvent, methyl ethyl ketone in which a thermosetting silicone adhesive sealant (trade name TSE3251-C; manufactured by Momentive Performance Materials) was adjusted to a solid content of 5% was prepared. Carbon black (trade name: Denka Black; manufactured by Denki Kagaku Kogyo Co., Ltd., powdered product) was added to this mixed solution in an amount of 21 parts by mass with respect to 100 parts by mass of the resin component, and the mixture was sufficiently stirred to form a coating for the surface layer A working solution was prepared. The base layer roller 4 whose surface was treated with excimer light was immersed in the coating liquid, pulled up and dried, and further heat-treated at 140 ° C. for 2 hours to obtain a charging roller. Table 2 shows the analysis results of this charging roller.

<Comparative example 4>
In the formation of the surface layer in Example 3, 3 sccm of hexamethylsiloxane vapor was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was set to 2 Pa. Furthermore, 200 W of electric power was supplied to the parallel plate electrodes by a high frequency power source. Otherwise, a charging roller was obtained in the same manner as in Example 21. Table 2 shows the analysis results of this charging roller.

<Comparative Example 5>
In the formation of the surface layer in Example 2, a mixed gas of 10 sccm of hexamethyldisiloxane vapor and 20 sccm of toluene vapor was introduced into the vacuum chamber as a source gas, and the pressure in the vacuum chamber was 8 Pa. Further, 30 W of electric power was supplied to the parallel plate electrodes by a high frequency power source. Otherwise, a charging roller was obtained in the same manner as in Example 2. Table 2 shows the analysis results of this charging roller.

<Evaluation 1: Continuous image printing durability test (DC charging)>
The charging rollers prepared in Examples 1 to 27 and Comparative Examples 1 to 5 were subjected to the following evaluation (1).

  The laser printer (product name: Color Laser Printer LBP-5300; manufactured by Canon Inc.) used for Evaluation 1 is for A4 paper / vertical output, the output speed of the recording medium is 21 ppm, and the resolution of the image is equivalent to 9600 dpi. . This laser printer employs a DC charging system as a primary charging bias. The charging roller is placed in contact with the photosensitive drum by a spring pressure of 500 g on one side, and is driven to rotate by the photosensitive drum. Further, on the surface of the charging roller, a polyimide film member was placed in surface contact for the purpose of cleaning and removing the attached dirt as shown in FIG.

(1) Evaluation of the presence or absence of cracks in the surface layer;
Each of the charging rollers according to Examples 1 to 27 and Comparative Examples 1 to 5 was incorporated in the laser printer cartridge as a charging roller. Each cartridge was then loaded into the laser printer. And each of low temperature and low humidity environment (environment 1: 15 ° C./10% RH), normal temperature and normal humidity environment (environment 2: 23 ° C./50% RH), high temperature high humidity environment (environment 3: 30 ° C./80% RH) Under the environment, 10,000 images with a printing density of 1% were output continuously.

  Regarding the charging roller after outputting 10,000 images, the charging roller was set on a rotating jig and the surface was wiped with water while rotating. About the water wiping, it wash | cleaned by pressing lightly on the roller surface using the nonwoven fabric containing water. Further, the roller after cleaning was air blown to remove water on the surface and dry the roller.

The surface of the charging roller after washing was observed with a microscope (trade name: Digital Microscope VH-8000; manufactured by Keyence Corporation). And the presence or absence of the crack generation and its extent were evaluated according to the following criteria.
A: No cracks are observed on the surface layer of the charging roller.
B: Very slight cracks are observed on the surface layer of the charging roller.
C: A crack is slightly observed on the surface layer of the charging roller.
D: Many cracks are generated in the surface layer of the charging roller.

<Evaluation 2: Severe neglect test>
Next, the following tests (2) and (3) were performed on the charging rollers prepared in Examples 1 to 27 and Comparative Examples 1 to 5.

(2) Photoconductor contamination test;
The effect of suppressing the seepage of the low molecular weight substance from the elastic layer of the charging roller by the surface layer according to the present invention was tested as follows.

  For the charging rollers obtained in Examples 1 to 27 and Comparative Examples 1 to 5 after outputting 10,000 sheets of images subjected to the evaluation 1, the surface is wiped with the charging roller set on a rotating jig and rotated. Went. About the water wiping, it wash | cleaned by pressing lightly on the roller surface using the nonwoven fabric containing water. Further, the roller after cleaning was air blown to remove water on the surface and dry the roller.

An environment of 40 ° C. and 95% RH with the charged rollers according to Examples 1 to 27 and Comparative Examples 1 to 5 after being washed in contact with a test piece formed of a photosensitive layer of an electrophotographic photosensitive member. Left under for 7 days. Thereafter, the contact portion of the photosensitive layer sheet left in contact was observed with an optical microscope, and the presence or absence of the exudate from the elastic layer and the occurrence of cracks in the photosensitive layer were evaluated based on the following criteria. The evaluation results are shown in Table 4 below.
A: Adhesion of exudate to the photosensitive layer and generation of cracks are not recognized.
B: Although adhesion of the exudate to the photosensitive layer is slightly observed, no crack is generated.
C: Slight adhesion of the exudate to the photosensitive layer is observed, and the occurrence of cracks is slightly observed.
D: Both the adhesion of the exudate to the photosensitive layer and the occurrence of cracks are clearly observed.

(3) Evaluation of image defects due to C set traces;
The compression deformation (C set) of the charging roller due to the charging roller being in contact with the photosensitive drum for a long time was tested as follows.

New charging rollers according to Examples 1 to 27 and Comparative Examples 1 to 5 were assembled in a process cartridge and left for 30 days in an environment of 40 ° C. and 95% RH. Thereafter, the process cartridge after being left was incorporated into a laser printer, and a halftone image was output. The image was visually observed, and the occurrence of horizontal lines for each charging roller cycle caused by the contact trace was evaluated based on the following criteria. The evaluation results are shown in Table 4 below.
A: A horizontal line of the charging roller cycle based on the contact mark is not recognized.
B: The horizontal line of the charging roller cycle based on the contact mark is very slightly recognized.
C: The horizontal line of the charging roller cycle based on the contact mark is slightly recognized.
D: The horizontal line of the charging roller cycle based on the contact mark is at a conspicuous level.

<Evaluation 3: Study on reuse of charging roller>
For each of the charging rollers of Examples 1 to 27 after image output, which were subjected to the evaluation of Evaluation 1, the charging roller was set on a rotating jig, and the surface was wiped with water while rotating. About the water wiping, it wash | cleaned by pressing lightly on the roller surface using the nonwoven fabric containing water. Further, the roller after cleaning was air blown to remove water on the surface and dry the roller. The washed charging roller was assembled in a new process cartridge, and again subjected to the same evaluation as in the above evaluation 1. The evaluation results are shown in Table 5 below.

<Example 28>
A charging roller was produced in the same manner as in Example 1 except that the base layer roller 2-1 was changed to the base layer roller 2-2.

<Example 29>
A charging roller was prepared in the same manner as in Example 2 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 30>
A charging roller was prepared in the same manner as in Example 3 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 31>
A charging roller was prepared in the same manner as in Example 4 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 32>
A charging roller was prepared in the same manner as in Example 5 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 33>
A charging roller was prepared in the same manner as in Example 6 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 34>
A charging roller was prepared in the same manner as in Example 7 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 35>
A charging roller was prepared in the same manner as in Example 8 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 36>
A charging roller was prepared in the same manner as in Example 9 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 37>
A charging roller was prepared in the same manner as in Example 10 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 38>
A charging roller was prepared in the same manner as in Example 2 except that the base layer roller 2-1 was changed to the base layer roller 2-2.

<Example 39>
A charging roller was prepared in the same manner as in Example 2 except that the base layer roller 2-1 was changed to the base layer roller 2-2.

<Example 40>
A charging roller was prepared in the same manner as in Example 13 except that the base layer roller 3-1 was changed to the base layer roller 3-2.

<Example 41>
A charging roller was prepared in the same manner as in Example 14 except that the base layer roller 4-1 was changed to the base layer roller 4-2.

<Example 42>
A charging roller was prepared in the same manner as in Example 15 except that the base layer roller 5-1 was changed to the base layer roller 5-2.

<Example 43>
A charging roller was prepared in the same manner as in Example 16 except that the base layer roller 6-1 was changed to the base layer roller 6-2.

<Example 44>
A charging roller was prepared in the same manner as in Example 17 except that the base layer roller 7-1 was changed to the base layer roller 7-2.

<Example 45>
A charging roller was prepared in the same manner as in Example 18 except that the base layer roller 8-1 was changed to the base layer roller 8-2.

<Example 46>
A charging roller was produced in the same manner as in Example 19 except that the base layer roller 9-1 was changed to the base layer roller 9-2.

<Example 47>
A charging roller was produced in the same manner as in Example 20 except that the base layer roller 10-1 was changed to the base layer roller 10-2.

<Example 48>
A charging roller was prepared in the same manner as in Example 21 except that the base layer roller 11-1 was changed to the base layer roller 11-2.

<Example 49>
A charging roller was produced in the same manner as in Example 22 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 50>
A charging roller was prepared in the same manner as in Example 23 except that the base layer roller 2-1 was changed to the base layer roller 2-2.

<Example 51>
A charging roller was prepared in the same manner as in Example 24 except that the base layer roller 2-1 was changed to the base layer roller 2-2.

<Example 52>
A charging roller was prepared in the same manner as in Example 25 except that the base roller 2-1 was changed to the base roller 2-2.

<Example 53>
A charging roller was produced in the same manner as in Example 26 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Example 54>
A charging roller was prepared in the same manner as in Example 2 except that the base layer roller 2-1 was changed to the base layer roller 2-2.

<Comparative Example 6>
A charging roller was prepared in the same manner as in Comparative Example 1 except that the base layer roller 11-1 was changed to the base layer roller 11-2.

<Comparative Example 7>
A charging roller was prepared in the same manner as Comparative Example 2 except that the base layer roller 11-1 was changed to the base layer roller 11-2.

<Comparative Example 8>
A charging roller was prepared in the same manner as in Comparative Example 3 except that the base layer roller 4-1 was changed to the base layer roller 4-2.

<Comparative Example 9>
A charging roller was prepared in the same manner as in Comparative Example 4 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Comparative Example 10>
A charging roller was produced in the same manner as in Comparative Example 5 except that the base layer roller 1-1 was changed to the base layer roller 1-2.

<Evaluation (4) Evaluation of presence or absence of cracks in surface layer (AC charging method)>
The following evaluation (4) was performed for each of the charging rollers of Examples 28 to 54 and Comparative Examples 6 to 10.

  The laser printer (product name: monochrome laser printer LBP-3210; manufactured by Canon Inc.) used for evaluation 4 is for A4 paper / vertical output, the output speed of the recording medium is 20 ppm, and the resolution of the image is equivalent to 2400 dpi. . The charging bias of this laser printer employs an AC charging method. The charging roller was placed in contact with the photosensitive drum by a spring pressure of 500 g on one side, and was driven to rotate following the photosensitive drum. The process cartridge of the laser printer used for this evaluation is not attached with a film member for the purpose of cleaning the surface of the charging roller.

  Each of the charging rollers according to Examples 28 to 54 and Comparative Examples 6 to 10 was incorporated as a charging roller in the laser printer cartridge. Each cartridge was then loaded into the laser printer. And each of low temperature and low humidity environment (environment 1: 15 ° C./10% RH), normal temperature and normal humidity environment (environment 2: 23 ° C./50% RH), high temperature high humidity environment (environment 3: 30 ° C./80% RH) Under the environment, 5000 images with a printing density of 1% were output continuously.

  About the charging roller after outputting 5,000 sheets of the image, the charging roller was set on a rotating jig, and the surface was wiped with water while rotating. About the water wiping, it wash | cleaned by pressing lightly on the roller surface using the nonwoven fabric containing water. Further, the roller after cleaning was air blown to remove water on the surface and dry the roller.

The surface of the charging roller after washing was observed with a microscope (trade name: Digital Microscope VH-8000; manufactured by Keyence Corporation). And the presence or absence of the crack generation and its extent were evaluated according to the following criteria.
A: No cracks are observed on the surface layer of the charging roller.
B: Very slight cracks are observed on the surface layer of the charging roller.
C: A crack is slightly observed on the surface layer of the charging roller.
D: Many cracks are generated in the surface layer of the charging roller.

1 is a diagram illustrating an electrophotographic image forming apparatus equipped with a charging roller according to a first embodiment of the present invention. FIG. It is sectional drawing of an example of the charging roller of this invention. It is sectional drawing of one example of the charging device of this invention. It is a schematic diagram of the SiOx film manufacturing apparatus by plasma CVD method. It is a schematic diagram of a shape measuring apparatus for measuring shape data such as the outer diameter of the roller and the outer diameter differential deflection.

Explanation of symbols

1 Conductive support (core metal)
DESCRIPTION OF SYMBOLS 2 Elastic layer 3 Surface layer 4 Photosensitive drum 5 Charging roller 6 Developing roller 7 Print media 8 Transfer roller 9 Fixing part 10 Cleaning blade 11 Exposure 12 Pre-charging exposure apparatus 13 Elastic regulation blade 14 Toner supply roller 18, 19, 20 Power supply 31 Conductivity Support (core)
32 Elastic Layer 33 Surface Layer 34 Charging Roller 35 Bearing 36 Spring 37 Frame 38 Contact 39 Charging Roller Surface Cleaning Member 41 Vacuum Chamber 42 Flat Plate Electrode 43 Raw Material Gas Cylinder and Raw Material Liquid Tank 44 Raw Material Supply Means 45 Gas Exhaust Means 46 High Frequency Supply Power Supply 47 Motor 48 Base layer roller

Claims (4)

An electrophotographic photoreceptor;
A charging member disposed in contact with the electrophotographic photosensitive member;
An electrophotographic image forming apparatus comprising charging means for applying a voltage to the charging member to charge the electrophotographic photosensitive member,
The charging member comprises a shaft core, an elastic layer, and a surface layer covering the surface of the elastic layer,
The surface layer includes a silicon oxide film containing carbon atoms chemically bonded to silicon atoms,
The silicon oxide film has an abundance ratio (O / Si) of oxygen atoms forming a chemical bond with silicon atoms to silicon atoms of 0.95 or more and 1.80 or less, and has a chemical bond with silicon atoms. An electrophotographic image forming apparatus, wherein an abundance ratio (C / Si) of formed carbon atoms to silicon atoms is 0.10 or more and 1.25 or less.   The electrophotographic image forming apparatus according to claim 1, wherein the surface layer is formed by a plasma CVD method.   The electrophotographic image forming apparatus according to claim 1, wherein the charging unit includes a unit that applies the AC voltage to the charging member, a DC voltage, or a DC voltage.   The electrophotographic image forming apparatus according to claim 1, wherein the charging member is driven to rotate with respect to the electrophotographic photosensitive member.

Images