JP2007065320A - Charging member, process cartridge, and electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging member which has a resistance made uniform by using a paint composition for the outermost layer (surface layer) of high productivity and has the resistance less changed with time, and a process cartridge and an electrophotographic device using the charging member. <P>SOLUTION: With respect to the charging member, the outermost layer 3 contains conductive fine particles and a phthalocyanine compound, and the conductive fine particles are composite conductive particles containing carbon black and/or graphite. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging member, a process cartridge and an electrophotographic apparatus using the same, and more specifically, a charging member for applying a voltage to charge the surface of an electrophotographic photosensitive member to be charged to a predetermined potential, and The present invention relates to a process cartridge and an electrophotographic apparatus using the same.

  In the electrophotographic charging process, a contact charging method in which a charging member is brought into contact with or close to a photoreceptor and a voltage is applied to the charging member to charge the surface of the photoreceptor has been put into practical use. As a specific example of the charging member used in such a contact charging method, a conductive roller having a conductive support and a coating layer covering the periphery thereof can be cited.

  The surface layer constituting the outermost layer of the coating layer of such a charging member is made of a resin imparted with conductivity by adding a conductive agent. As the conductive agent used for these surface layers, an electron conductive conductive agent is used because it does not contaminate the photoreceptor. Conventionally, conductive carbon black such as ketjen black, furnace black, and acetylene black has been used as an electronic conductive agent. Conductive carbon black is an excellent conductive agent that can exhibit conductivity when added in a small amount. However, there is a problem when it is used in an electrically intermediate resistance region such as a surface layer of a charging member. That is, when trying to make a surface layer in the middle resistance region using carbon black, since it is used in the so-called percolation region of carbon black, a slight unevenness in the dispersion state and a slight difference in material properties result, and the electrical resistance of the surface layer There is a problem of greatly affecting the value. This is considered to be because carbon black having a high conductivity has a large aggregate diameter, and the electrical resistance as the surface layer is greatly influenced by a subtle difference in the contact state of the structure.

  In order to solve such a problem of carbon black, various proposals have been made. One of them is the use of composite particles coated with carbon black particles made of polymer material as a conductive agent, thereby improving the dispersibility of the conductive agent, reducing unevenness in the dispersed state, and uniform resistance. There is a proposal of a conductive material for a charging roller that has been developed (see, for example, Patent Document 1).

  Furthermore, in order to control the surface property of the conductive roller for the purpose of preventing surface contamination of the roller and improving the charging uniformity, various roughening agents are added to control the surface roughness (for example, patents). References 2 and 3).

  However, the surface layer is applied to the charging member coated with a coating material in which both composite particles coated with particles of polymer material and a roughening agent are simultaneously dispersed with carbon black as a surface layer binder. It has been found that the resistance change with the passage of time increases, the viscosity of the surface layer paint produced when applying the surface layer changes with time, and the composite particles settle, resulting in problems in productivity.

This is because the dispersibility of the composite particles is hindered by the resin particles and the dispersibility is likely to be lowered, and the composite particles are likely to aggregate over time due to the interaction with the resin particles, so that the coating is likely to settle.
JP 2003-162106 A Japanese Patent No. 3024248 JP 2003-316111 A

  The present invention is to provide a charging member, a process cartridge and an electrophotographic apparatus using the charging member, which have solved the above-mentioned problems. Specifically, by using a highly productive coating composition for the outermost layer (surface layer), in particular, a uniform resistance can be achieved, and a charging member with little resistance change with time, a process cartridge using the charging member, and An electrophotographic apparatus is provided.

  The present invention is a charging member characterized in that the outermost layer contains at least conductive fine particles and a phthalocyanine compound.

  The present invention also provides a process cartridge and an electrophotographic apparatus using the charging member.

  According to the present invention, it is possible to provide a charging member with little change in resistance with time, high paint stability, and high productivity, a process cartridge and an electrophotographic apparatus using the same.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1A is a schematic cross-sectional view of a charging roller which is an embodiment of the charging member according to the present invention. In the figure, reference numeral 1 denotes a conductive support, which is provided with an elastic layer (conductive elastic base layer) 2 around it and further covered with an outermost layer (surface layer) 3 of the charging roller. (B) is a cross-sectional view in the direction along the longitudinal direction of the conductive support 1 of the charging roller of (a). And the surface layer 3 contains the composite electroconductive particle by which the electroconductive material was bound to the surface of a core particle, the bridge | crosslinked resin particle (preferably average particle diameter of 1-15 micrometers), and a phthalocyanine compound.

  By adding the phthalocyanine compound, the phthalocyanine compound of the formula (1) adheres to the surfaces of the composite conductive particles and the resin particles, thereby reducing the interaction force between the composite conductive particles and the resin particles. The reaggregation of the conductive particles is prevented, and the settling of the composite conductive particles with the passage of time of the paint and the resistance change with the passage of time are suppressed.

(1) Phthalocyanine compound The structure of the phthalocyanine compound of the present invention is:

It is expressed. In the above structural formula, M represents a central metal, X _{1 to} X ₄ represent Cl or Br, and n, m, l, and k are integers from 0 to 4.

  The central metal of phthalocyanine is composed of elements such as Na, K, Be, Ca, Ba, Cd, Mg, Hg, etc., which have strong ion binding elements, and Cu, Fe, Zn, Co, Pt, Cr, which have strong covalent elements. , Ni, Pt and the like. Also known are compounds such as aluminum chlorophthalocyanine, chloroindium phthalocyanine, oxyvanadyl phthalocyanine, chlorogallium phthalocyanine and oxytitanium phthalocyanine, which are used in the charge generation layer of electrophotographic photoreceptors. Of these, many phthalocyanine compounds are known to have various crystal forms. For example, metal-free phthalocyanines include α-type, β-type, γ-type, δ-type, ε-type, x-type, and τ-type. It is generally known that phthalocyanines include α-type, β-type, γ-type, δ-type, ε-type and x-type.

  Since the phthalocyanine compound of the present invention is used after being mixed and well dispersed with conductive fine particles, any crystal system can be used as a raw material. Before dispersion, if necessary, it is processed by an acid pacing method to make it amorphous, or after stirring for 1 hour or more in methanol, it is dried under reduced pressure, and further, n-propyl ether, Ether solvents such as n-butyl ether, iso-butyl ether, sec-butyl ether, n-amyl ether, n-butyl methyl ether, n-butyl ethyl ether, ethylene glycol n-butyl ether or monoterpene hydrocarbons such as terpinolene and pinene Milling for 5 hours or more, preferably 10 hours or more using a solvent such as a solvent or liquid paraffin as a dispersion medium (using a milling device such as a sand mill or ball mill together with a dispersion medium such as glass beads, steel beads or alumina balls) By crushing) It may have been adjusted to a particular crystal form Te.

  In the present invention, the phthalocyanine compound prevents re-aggregation of the conductive fine particles, and prevents precipitation of the conductive fine particles with the passage of time of the paint and a change in resistance with the passage of time.

  The amount of the phthalocyanine compound added is generally 0.1 to 1000 parts by mass, preferably 1 to 100 parts by mass with respect to 100 parts by mass of the conductive fine particles. If the amount is less than 0.1 parts by mass, the effect of suppressing sedimentation and resistance change of the composite conductive particles is reduced, and if the amount is more than 1000 parts by mass, the volume resistivity of the outermost layer (surface layer) of the coating layer becomes too large, which is not preferable. .

(2) Composite conductive particles In the present invention, by using composite conductive particles in which a conductive material is bound to the surface of the core particles, the leakage resistance is excellent, and there is little uneven resistance, resulting in poor charging. It is possible to obtain an image having excellent charging uniformity without causing the occurrence of the phenomenon. That is, in the present invention, the composite conductive particles used for adjusting the resistance of the outermost layer (resin layer) constituting the charging member are obtained by binding a conductive material to the core particles, and preferably by coating a thin film. The semiconductive particles having a large resistance and a medium resistance can be obtained. Also, by using semi-conductive particles, the resistance of the resin layer can be made semi-conductive even if blended in a large amount compared to a conductive agent such as carbon black, which is generally used in the resin layer of the charging member. And leakage resistance can be improved. In addition, since a medium resistance particle is dispersed in a large amount in the resin layer, the difference in electrical resistance between the resin and the composite conductive particle is small, and excellent charging uniformity with a small variation in resistance is exhibited.

Conductive material;
Examples of the conductive material used for the composite conductive particles include carbon black. There is no restriction | limiting in particular as carbon black, Generally what is used as an electroconductivity imparting agent in an electroconductive roller is mentioned. Examples of the conductive carbon black include acetylene black by an acetylene method, furnace black by a furnace method, and special carbon black by a shell-type gasification furnace. As a result of our repeated studies, it was found that acidic carbon black is particularly suitable as carbon black. It became clear that the resistance change due to continuous energization can be reduced by using acidic carbon black. PH is preferably in the range of 2 to 6.5, and more preferably in the range of 2 to 5. The reason why the above effects can be obtained is considered as follows. As a mechanism of current deterioration, an acidic functional group is generated by the oxidation of carbon black by an oxidizing substance such as ozone that is generated when current is applied, and the generated σ electrons obstruct the original π-electron orbit. We believe that the resistance of black has increased and resistance has changed. Since acidic carbon black has already oxidized the surface of carbon black, it is considered that the oxidation reaction at the time of energization does not easily occur, and the resistance change due to the energization can be reduced.

Core particles;
The core particle used for the composite conductive particle is not particularly limited as long as the volume resistance is larger than that of the coating layer, but an inorganic compound that easily obtains a small particle diameter is preferable, and oxides such as silica and titanium oxide, double oxides, etc. Further, nitride, carbide, ceramic and the like can be used.

An adhesive used between the core particles and the conductive material;
Examples of the adhesive include organosilane compounds formed from alkoxysilanes, and polysiloxanes, modified polysiloxanes, terminal-modified polysiloxanes, or mixtures thereof.

  Specific examples of the alkoxysilane include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane. Examples include methoxysilane and decyltrimethoxysilane.

  In view of the adhesion strength of carbon black to the core particle surface, an organosilane compound produced from methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, isobutyltrimethoxysilane, and phenyltriethoxysilane is more preferable, and most preferably It is an organosilane compound produced from methyltriethoxysilane, methyltrimethoxysilane and phenyltriethoxysilane.

  Among the polysiloxanes, polysiloxanes having methylhydrogensiloxane units are preferred in consideration of the adhesion strength of carbon black to the surface of the core particles. Among the modified polysiloxanes, the polyether-modified polysiloxane and the terminal are carboxylic acids. Modified terminal carboxylic acid modified polysiloxanes are preferred.

  The adhesive is attached to the surface of the core particle by a known powder surface treatment method. Known adhesion methods include dry methods and wet methods, and wet methods include aqueous solution methods, organic solvent methods, and spray methods.

  The composite conductive particles in the present invention, for example, silica coated with carbon black, is prepared by applying shearing to a powder using a wheel-type kneader. As kneading conditions, the kneading time and the number of wheel rotations are set as appropriate, and kneading is performed until most of the carbon black adheres to the silica. The carbon black bonded to the surface of the composite conductive particles obtained by adhering carbon black while applying shear in this way has a small structure structure and a structure reflecting the shape and particle size of silica.

  The thickness of the coating layer of the composite conductive particles whose surface is particularly well coated with the conductive agent can be controlled by the amount of conductive material such as carbon black added to the core particles such as silica under the above production conditions. For example, when carbon having a primary particle diameter of 14 nm is coated with carbon black at a thickness of 2 nm, it can be prepared by adding 110 parts by mass of carbon black to 100 parts by mass of silica and kneading.

  The coated composite conductive particles may be classified to have a uniform particle size. As the classification method, for example, a method using sedimentation separation such as centrifugal separation or thickener, or a wet classification device using a cyclone is suitable.

The amount of the composite conductive particles added to the surface layer resin is such that the volume resistivity of the surface layer resin is a low temperature and low humidity environment (L / L: 15 ° C./10% RH), a normal temperature and normal humidity environment (N / N: 23 ° C./55). % RH) and a high-temperature and high-humidity environment (H / H: 30 ° C./80%RH), the medium resistance region (volume resistivity is 1 × 10 ⁶ to 1 × 10 ¹⁵ Ω · cm) is determined.

  When the volume resistivity of the surface layer is smaller than this, when used as a charging roller, when there is a pinhole in the photoconductor, an excessive current flows through the pinhole and leaks, and the leaked trace appears in the image. Therefore, it is not preferable. On the other hand, if the volume resistivity is too high, no current flows through the charging roller, the photosensitive member cannot be charged to a predetermined potential, and the image does not have the desired density. Further, even if the potential is charged to a certain level, it is not preferable because the charging becomes non-uniform and appears on the image.

  For the volume resistance of the surface layer, the surface layer is peeled off from the roller state and cut into a strip of about 5 mm × 5 mm. Metal is vapor-deposited on both sides to produce an electrode and a guard electrode, and a voltage of 200V is applied using a microammeter (ADVANTEST R8340A ULTRA HIGH RESISTANCE METER Co., Ltd., Advantest) to measure the current after 30 seconds. And calculated from the film thickness and the electrode area.

  As a compounding quantity of composite electroconductive particle, 1-80 mass% is preferable with respect to the surface layer after coating, Most preferably, it is 5-60 mass%. The primary particle diameter of the composite conductive particles is preferably 0.1 μm or less by differential scanning electron microscope observation. Disperse by a known method until the secondary particles become small in the surface coating. The secondary particle diameter is a value of volume average particle diameter MEDIAN measured by a centrifugal sedimentation type particle size distribution analyzer (CAPA700: manufactured by Horiba, Ltd.), and is preferably 1.0 μm or less, and particularly preferably 0.5 μm or less. If the secondary particle diameter is large, the variation due to the position of the resistance of the surface layer material becomes large, which causes uneven charging.

(3) Crosslinked resin particles The surface layer of the charging member of the present invention contains crosslinked resin particles for roughening the surface of the charging roller. If it is not cross-linked, it may be dissolved when used as a coating for surface coating. Although it does not specifically limit as a monomer which makes the crosslinked resin particle, From the ease of superposition | polymerization etc., a vinyl-type monomer is used suitably.

  Examples of the vinyl monomer used in the present invention include acrylic acid esters such as methyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, and methacrylates such as methyl methacrylate, butyl methacrylate and hexyl methacrylate, Examples thereof include aromatic vinyl monomers such as styrene, p-methylstyrene, and α-methylstyrene, vinyl acetate, and acrylonitrile.

  In order to form resin particles in which the resin particles are crosslinked, in the present invention, a crosslinkable vinyl monomer having two or more vinyl groups in the molecule is used in addition to the above vinyl monomer. Examples of such a crosslinkable vinyl monomer include ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and the like. The addition amount of these crosslinkable vinyl monomers is preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the noncrosslinkable vinyl monomer.

  These crosslinked resin particles are polymerized by seed emulsion polymerization, dispersion polymerization, suspension polymerization, or the like, but are preferably polymerized by suspension polymerization because there is little residue of a low molecular surfactant or the like. The polymerization initiator is not particularly limited, and examples thereof include peroxide catalysts such as benzoyl peroxide and lauroyl peroxide, and azo catalysts such as azobisisobutyronitrile.

  It is more preferable that the crosslinked resin particles used in the present invention have a more nearly spherical shape.

  Specifically, the average circularity is preferably 0.95 or more. By precisely controlling the particle shape of the resin particles so that the average circularity is 0.95 or more, the surface roughness of the charging roller becomes uniform, and even charging characteristics can be obtained even when used at different process speeds. Obtainable.

  Furthermore, the circularity standard deviation is more preferably less than 0.040. By precisely controlling the particle shape of the resin particles so that the standard deviation of the circularity is less than 0.040, the ratio of resin particles far away from the true sphere is reduced, and the resin is suddenly applied to the surface of the charging roller. The probability of disturbing charging due to generation of particle protrusions is suppressed, the surface roughness of the charging roller becomes more uniform, and even charging characteristics can be obtained even when used at different process speeds.

  The circularity in the present invention is used as a simple method for quantitatively expressing the particle shape. In the present invention, the particle shape is measured using a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics. The circularity is obtained by the following formula. Furthermore, as shown by the following equation, a value obtained by dividing the total roundness of all the measured particles by the total number of particles is defined as the average circularity.

(In the above formula, ci represents the circularity of each of m particles)

  Here, the “particle projected area” is the area of the binarized resin particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the resin particle image. Define.

  In addition, “FPIA-1000”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity and the circularity standard deviation. Degrees of 0.400 to 1.000 at intervals of 0.010, 0.400 or more and less than 0.410, 0.410 or more and less than 0.420 ... 0.990 or more and less than 1.000 and 1.000 A calculation method is used in which the average circularity and the circularity standard deviation are calculated using the center value and frequency of the division points.

  Error between each value of average circularity and circularity standard deviation calculated by this calculation method and each value of average circularity and circularity standard deviation calculated by the above-described calculation formula that directly uses the circularity of each particle. Is very small and substantially negligible. Therefore, in the present invention, the circular shape of each particle described above is used for the reason of handling data such as a short calculation time and a simplified calculation formula. This calculation method is partially changed by using the concept of a calculation formula that directly uses the degree.

  The circularity in the present invention is an index indicating the degree of unevenness of particles, and is 1.000 when the particles are completely spherical, and the circularity becomes smaller as the surface shape becomes more complicated.

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “UH-50 type” (manufactured by SMT Co., Ltd.) equipped with a titanium alloy chip of φ5 mm as a vibrator is used. To do. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more.

  For the shape measurement of the resin particles, the flow type particle image measuring device is used, and the dispersion concentration is readjusted so that the resin particle concentration at the time of measurement is 3000 to 10,000 particles / μl, and 1000 or more resin particles are obtained. measure.

  The average particle size of the resin particles is preferably 100 μm or less, more preferably 0.5 to 50 μm, and still more preferably 1 to 25 μm. Moreover, it is preferable that there are substantially no resin particles having a particle size of 3 times or more the mass average particle size. If the particle size is too large, the charging roller surface becomes too rough and charging becomes uneven. On the other hand, if it is too small, the effect of stabilizing charging in the region of low process speed by adding resin particles does not appear.

  Below, the specific example of the particle size measurement of the resin particle in this invention is shown.

  0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 to 150 ml of the electrolyte solution, and 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample is suspended is dispersed for 1 to 3 minutes with an ultrasonic disperser, and an aperture adjusted to an appropriate resin particle size such as 17 μm or 100 μm with a Coulter counter multisizer is used as a reference with a volume of 0.3. The particle size distribution of ˜40 μm is measured. The number average particle diameter and mass average particle diameter measured under these conditions are determined by computer processing, and the cumulative ratio of the mass average particle diameter more than the triple diameter cumulative distribution is calculated from the volume-based particle size distribution to obtain the triple diameter cumulative distribution or more. Find the cumulative value of.

  The addition amount of the resin particles is preferably 1 to 80% by mass as a mass ratio in the surface layer after coating. If the amount is less than 1% by mass, the effect of stabilizing the charge by adding resin particles cannot be obtained. If the amount is more than 80% by mass, it is difficult to control the viscosity of the surface layer paint, and it is difficult to uniformly apply the coating. Absent.

(4) Binder resin As the binder for the surface layer, a resin such as a thermosetting resin or a thermoplastic resin is used.

  As the binder for the surface layer of the present invention, a urethane resin obtained by crosslinking a lactone-modified acrylic polyol with isophorone diisocyanate and hexamethylene diisocyanate is particularly preferably used.

  When hexamethylene diisocyanate is used alone as the isocyanate that crosslinks the polyol on the surface layer, the surface layer is flexible and the surface after the application of the roller is uniformly finished. There is a possibility that uncured components (for example, ionic conductive agent or plasticizer) in the conductive elastic base layer may not be sufficiently prevented from oozing out to the roller surface. The presence of such a leachable substance may contaminate the photoreceptor.

  On the other hand, when isophorone diisocyanate is used alone as the isocyanate that crosslinks the polyol on the surface layer, the surface layer has a great effect of preventing the exudation of the exuding substance from the base layer, but the surface layer becomes too hard to cause heat shrinkage of the base layer rubber. There is an adverse effect that it is impossible to follow, wrinkles are generated on the surface of the completed roller, and the desired roller cannot be obtained in terms of the surface roughness and shape of the roller.

  The surface layer of the roller of the present invention provides a surface layer resin having good properties that combines the exuding substance blocking property of isophorone diisocyanate and the flexibility of hexamethylene diisocyanate, and the exuding material from the ionic base layer is provided on the roller surface. Thus, it is possible to obtain a charging roller having a good surface shape while preventing it from seeping out.

  That is, the resin used for the surface layer in the present invention is such that lactone-modified acrylic polyol, isophorone diisocyanate, and hexamethylene diisocyanate are blended and cured, so that isophorone diisocyanate and hexamethylene diisocyanate react randomly with lactone-modified acrylic polyol. Thus, a crosslinked structure is formed.

  The isocyanate used in the present invention is more preferably an isocyanurate type trimer. The rigid trimer of the molecule serves as a cross-linking point, the surface layer can be cross-linked more closely, and the exudation substance from the ionic base layer is more effectively prevented from exuding on the roller surface. Can do.

  The isocyanate used in the present invention is more preferably a blocked isocyanate in which an isocyanate group is blocked with a blocking agent. The reason for this is that the isocyanate group is easy to react, and if the surface coating is left at room temperature for a long time, the reaction gradually proceeds and the characteristics of the coating may change. On the other hand, the blocked isocyanate has an advantage that the active isocyanate group is blocked and does not react up to the dissociation temperature of the blocking agent, so that the paint can be easily handled. Examples of the blocking agent for masking include phenols such as phenol and cresol, lactams of ε-caprolactam, and oximes such as methyl ethyl ketoxime. In the present invention, oximes having a relatively low dissociation temperature are used. preferable.

  1 illustrates a trimer of a lactone-modified acrylic polyol and a blocked isocyanate constituting the surface resin of the present invention.

  In the formula, n, m, and k are positive integers.

  On the other hand, the OH value of the lactone-modified acrylic polyol is preferably about 80 KOHmg / g. When the OH value is small, it is difficult to crosslink with an isocyanate, whereby the resin becomes too soft and easily sticks to the photoreceptor. If the OH group is too large, the coating film becomes too hard and easily cracks.

  The lactone-modified acrylic polyol of the present invention is a copolymer of styrene and acrylic whose molecular chain skeleton has an appropriate hardness and non-contaminating property. In addition, the modified lactone group having a hydroxyl group at the terminal serves as a number of cross-linking points, and it is possible to cross-link closely with an isocyanate, thereby preventing the unvulcanized component from exuding from the base layer. An example of such a lactone-modified acrylic polyol is Plaxel DC2009 (manufactured by Daicel Chemical Industries, Ltd.).

  The glass transition temperature Tg of the resin used for the surface layer is a viscoelasticity measurement method, and the peak temperature is preferably 45 ° C. or higher, and particularly preferably 50 ° C. or higher. If the temperature is lower than 45 ° C., it is not preferable because it may be stuck to the photoconductor when left in contact with the photoconductor for a long period of time, or the surface of the charging roller may be easily contaminated with toner or the like. .

  The measuring method of the glass transition temperature Tg in the present invention is as follows. First, a surface layer sample for measurement is peeled off from the roller state and cut into a strip of about 5 mm × 40 mm. As a measuring device, a dynamic viscoelasticity measuring device RSA-II (manufactured by Rheometrics Scientific F.E.) is used, and a film tension fixture is used as a jig. The measurement is performed in an auto tension mode in a temperature range of −50 ° C. to 150 ° C. with a measurement frequency of 6.28 rad / sec, a temperature rising rate of 5 ° C./min, and an initial strain of 0.07 to 0.25%. The temperature dispersion of the loss tangent tan δ is measured, and the peak temperature is defined as Tg.

  Although not particularly limited, too high Tg is not preferable because the flexibility of the resin is lost and the coating film is easily broken. Tg is adjusted by the ratio or amount of isocyanate to be crosslinked.

  The blending ratio of the lactone-modified acrylic polyol resin and the isocyanate is the ratio of the number of NCO groups (A) in the isocyanate in the blended paint to the number of OH groups (B) in the lactone-modified acrylic polyol resin, NCO The / OH ratio = A / B is preferably in the range of 0.1 to 2.0, and particularly preferably adjusted to be in the range of 0.3 to 1.5.

  By cross-linking the lactone-modified acrylic polyol with isocyanate, it prevents the low-molecular component from oozing out from the conductive elastic base layer, and the surface layer on which the charging roller itself is not easily contaminated with toner and does not contaminate the photoreceptor. Can be formed.

(5) Others It is also preferable to mix various leveling agents in the resin paint forming the outermost layer (surface layer). Examples of the leveling agent include silicone oil.

  In order to increase the surface potential of the member to be charged by the charging roller, insulating fine particles can also be contained.

  Examples of the base material for the insulating fine particles include metal oxide fine particles, spherical carbon fine particles, silica fine particles, and composite oxides such as strontium titanate fine particles, calcium titanate fine particles, and silicon titanate fine particles. Among these, inorganic fine particles are preferable, insulating inorganic fine particles are particularly preferable, and titanium oxide is particularly preferable. In particular, metal oxide or double oxide insulating fine particles having a large relative dielectric constant are preferable. When inorganic fine particles having a large relative dielectric constant are used as a base material, it is effective for increasing the charging potential of the charging roller and uniformly charging the object to be charged.

  The insulating fine particles are more preferably subjected to a surface treatment.

  Insulating fine particles may also include first fine particles obtained by subjecting a base material to surface treatment with a silane coupling agent, and a base material of the same type as the base material after surface treatment with a silane coupling agent, followed by silicone oil or silicone varnish. Both of the surface-treated second fine particles can be blended and contained.

  Preferably, the first fine particle base material and the second fine particle base material are of the same type. Here, the same kind of base material means that the chemical molecular composition, particle diameter, and surface area are almost equal. Specifically, the composition of the molecule represented by the general molecular formula and the composition of the element represented by the composition formula are generally within a variation of plus or minus 20%, more preferably plus or minus 10%. It is preferable to be within the range. Regarding the particle size, it is preferable that the average particle size is approximately within 10 times, preferably within 2 times. Further, it is preferable that the surface area by the BET method or the like is approximately within 10 times, preferably within 2 times. If the physical properties as described above are different between the base material of the first fine particles and the base material of the second fine particles, the stability of the coating material for forming the surface layer may be impaired.

  As the particle diameter of the fine particles used in the present invention, the number average particle diameter (length average) is 1.0 μm or less, and more preferably 0.001 μm to 0.5 μm. By setting the number average particle diameter of the fine particles within this range, the problem of sedimentation in the paint is less likely to occur, and uniform surface treatment can be achieved.

  An electron microscope is used for the measurement of the particle diameter. The shooting magnification is 100,000 times, but if it is difficult, the image is magnified to 100,000 times after shooting at a low magnification. Measure the primary particle size on the photo. At this time, the major axis and the minor axis are measured, and the average value is defined as the particle size. This is measured for 100 samples, and the 50% value is taken as the average particle size.

(5-1) Surface treatment with a coupling agent;
As the coupling agent (a central element such as silicon, titanium, aluminum and zirconium is not particularly selected), an alkoxysilane coupling agent and a fluoroalkylalkoxysilane coupling agent are particularly preferable.

  Examples of coupling agents include silane coupling agents and titanate coupling agents. Examples of the silane coupling agent include isobutylsilane, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyldimethyl. Chlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilamen, dimethyldi Ethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyl Rutetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2-12 siloxane units per molecule, each containing a hydroxyl group bonded to each silicon atom in the terminal unit Dimethylpolysiloxane.

  As the hydrolyzing group of the coupling agent, for example, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group having a relatively high hydrophilicity is used. In addition, an acryloxy group, a methacryloxy group, modified products thereof, halogen, and the like are also used. In addition, the hydrophobic group may be bonded via a carboxylic acid ester, alkoxy, sulfonic acid ester or phosphoric acid ester, or directly in the bonding form with the central element. Furthermore, functional groups such as ether bonds, epoxy groups and amino groups may be included in the structure of the hydrophobic group. By treating with the coupling agent, it is possible to suppress the adsorption of moisture to the surface of the fine particles, and to obtain a surface layer material with smaller environmental fluctuations.

  As a method for hydrophobizing the fine particles, for example, in the case of a silane coupling agent, there are two methods, a dry method and a wet method.

(5-1-a) Dry method A silane coupling agent is sprayed or blown in a vapor state while thoroughly stirring the conductive agent. Add heat treatment if necessary. More specifically, it is preferable to use a dry method in which a silane coupling agent is allowed to react with fine particles in the form of cloud in the presence of water vapor. In the treatment with the silane coupling agent, the silane coupling agent is treated in the presence of water vapor, so that the water vapor acts as a catalyst, and the reaction of the silane coupling agent can be enhanced, thereby enabling uniform surface treatment. . The presence of water vapor during the treatment of the silane coupling agent is preferable in order to cause the silane coupling agent and the base material to react well.

(5-1-b) Wet method A conductive agent is dispersed in a solvent, and a silane coupling agent is also diluted with water or an organic solvent and added while stirring vigorously in a slurry state. This method is preferable for uniform treatment. Furthermore, there are the following three methods as specific methods for the silane pretreatment of the conductive agent surface.

(5-1-b-1) Aqueous solution method About 0.1 to 0.5% by mass of silane is injected and dissolved in water having a constant pH or water-solvent with sufficient stirring and hydrolyzed. After the fine particles are immersed in this solution, they are filtered or squeezed to remove water to some extent and then sufficiently dried at 120 to 130 ° C.

(5-1-b-2) Organic solvent method Silane is dissolved in an organic solvent (alcohol, benzene, halogenated hydrocarbon) containing a small amount of water and a hydrolysis solvent (hydrochloric acid, acetic acid). After immersing the fine particles in this solution, the solution is filtered or squeezed to remove the solvent and sufficiently dried at 120 to 130 ° C.

(5-1-b-3) Spray Method An aqueous solution of silane or a solvent solution is sprayed while vigorously stirring fine particles. Then, it is sufficiently dried at 120 to 130 ° C.

  In this invention, it is good to add and process a silane coupling agent in 5-60 mass parts with respect to 100 mass parts of fine particle raw materials, More preferably, in the range of 10-50 mass parts. When the amount is less than 5 parts by mass, the surface treatment is not sufficient, and precipitation tends to occur, and the stability of the coating material for coating the surface layer is deteriorated. It can be difficult.

(5-2) Surface treatment with silicone oil;
As a silicone oil, what is represented by the following general formula (I) is preferable.

  In the above general formula (I), R is an alkyl group having 1 to 3 carbon atoms, R ′ is a silicone oil-modified group such as alkyl, halogen-modified alkyl, phenyl, and modified phenyl, and R ″ is 1 to 1 carbon atoms. An alkyl or alkoxy group of 3. m and n are numbers satisfying m ≧ 0, n ≧ 0, and m + n> 0.

  Specific examples of the general formula (I) include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil.

  In the present invention, as the silicone oil, a modified silicone oil having a structure represented by the following general formula (II) can also be used.

In the general formula (II), R ₁ and R ₆ represent a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, R ₂ represents an alkylene group or a phenylene group, and R ₃ represents a nitrogen-containing heterocycle in its structure. R ₄ and R _{5 each} represent a hydrogen atom, an alkyl group or an aryl group, and R ₂ may not be present. However, the above alkyl group, aryl group, alkylene group, and phenylene group may have an amine, or may have a halogen as a substituent as long as the chargeability is not impaired. m is a number of 1 or more, and n and k are positive numbers including 0. However, n + k is a positive number of 1 or more.

  The most preferred structure among the above structures is one in which the number of nitrogen atoms in the side chain containing a nitrogen atom is 1 or 2. An example of the structure of an unsaturated heterocyclic ring having nitrogen is given below.

  An example of the structure is given below as a saturated heterocyclic ring having nitrogen.

  However, the present invention is not limited to the above compound examples, but those having a 5-membered or 6-membered heterocyclic ring are preferred. Examples of the derivative include a derivative in which a hydrocarbon group, a halogen group, an amino group, a vinyl group, a mercapto group, a methacryl group, a glycidoxy group, or a ureido group is introduced into the above compound group. These may be used alone or in combination of two or more.

(5-3) Surface treatment with silicone varnish;
Examples of the silicone varnish used in the present invention include methyl silicone varnish and phenylmethyl silicone varnish. In particular, in the present invention, it is preferable to use methyl silicone varnish. Methyl silicone varnish is a polymer composed of T ³¹ units, D ³¹ units, and M ³¹ units represented by the following structure, and is a three-dimensional polymer containing a large amount of T ³¹ units.

  Specifically, the methyl silicone varnish or the phenyl methyl silicone varnish is a substance having a chemical structure represented by the following structural formula (III).

In the formula, R ³¹ represents a methyl group or a phenyl group.

In the above silicone varnish, the T ³¹ unit is particularly an effective unit for imparting a good thermosetting property to a three-dimensional network structure. It is preferable to use a silicone varnish containing the T ³¹ unit in a range of 10 to 90 mol%, particularly 30 to 80 mol%.

  Such a silicone varnish has a hydroxyl group at the end or side chain of the molecular chain, and is cured by a dehydration condensation reaction of the hydroxyl group. Examples of the curing accelerator that can be used to accelerate the curing reaction include fatty acid salts such as zinc, lead, cobalt, and tin; and amines such as triethanolamine and butylamine. Of these, amines can be preferably used.

In order to make the silicone varnish as described above into an amino-modified silicone varnish, a part of methyl group or phenyl group present in the T ³¹ unit, D ³¹ unit and M ³¹ unit is substituted with a group having an amino group. do it. Examples of the group having an amino group include those represented by the following structural formulas, but are not limited thereto.

  As a surface treatment method of the base material with these silicone oils or silicone varnishes, for example, fine particles and silicone oil or silicone varnish are mixed using a mixer; and silicone oil or silicone varnish is sprayed into fine powder The method of spraying using is mentioned.

  As a treatment form for producing the second fine particles used in the present invention, it is preferable to perform treatment by combining both a silane coupling agent and silicone oil or silicone varnish. As a preferable treatment form, first, treatment with a silane coupling treatment agent and then treatment with silicone oil or silicone varnish can be mentioned. Among these, the form of treating with silicone oil after treating with isobutylsilane is particularly preferred.

Examples of the surface treatment method of the insulating base material with silicone oil and / or silicone varnish include a method in which fine particles and silicone oil not diluted with a solvent are directly mixed using a mixer such as a Henschel mixer; and A method of spraying silicone oil that has not been diluted with a solvent onto the fine particles may be mentioned. In this case, the silicone oil and / or the silicone varnish is more preferable since it can achieve a more uniform treatment if it is heated to a temperature of 50 to 200 ° C. to reduce the viscosity. As described above, in the present invention, since the silicone oil and / or silicone varnish is used for the surface treatment without being diluted in a solvent, it is preferable to use one having a kinematic viscosity at 25 ° C. of 500 mm ² / s or less.

  Therefore, in order to obtain the surface-treated fine particles used in the present invention, the fine particles are treated with a silane coupling treatment agent, then sprayed with silicone oil or silicone varnish, and then heat-treated at a temperature of 200 ° C. or higher. Are preferably used. When the fine particles are treated with a silane coupling agent and then sprayed with silicone oil or silicone varnish, the method is heated at a high temperature of 200 ° C. or higher. It becomes possible to adhere to.

  Silicone oil or silicone varnish is used in the range of 2 to 40 parts by weight, more preferably 5 to 35 parts by weight, with respect to 100 parts by weight of the base material or the base material subjected to the coupling treatment. Within this range, even when the charging member is left in a severe high-temperature and high-humidity environment, surface treatment components such as silicone oil and silicone varnish are prevented from seeping out onto the surface of the charging member. be able to. In addition, a high-quality surface layer can be formed and the problem of frictional memory can be alleviated.

(5-4) Ratio of the first fine particles to the second fine particles;
As a mixing amount ratio of the first fine particles and the second fine particles subjected to different surface treatments using the same base material, the mixing ratio of the first fine particles to the second fine particles is 1: 1 to 1000: 1. More preferably, it is 10: 1 to 100: 1. By including in the surface layer at such a ratio, the charging member that can suppress the occurrence of image unevenness due to contact with the photoreceptor and the coating unevenness when the surface layer is applied and has a stable charging ability. It can be.

Conductive Support The conductive support 1 in FIG. 1 is a cylinder having a nickel plating with a thickness of 5 μm, for example, on the surface of a carbon steel alloy. In addition to the materials constituting the conductive support, for example, metals such as iron, aluminum, titanium, copper and nickel, alloys such as stainless steel, duralumin, brass and bronze containing these metals, and carbon black and carbon fibers are also included. It is also possible to use a known material that is rigid and shows conductivity, such as a composite material hardened with plastic. Moreover, as a shape, it can also be set as the cylindrical shape which made the center part the cavity other than column shape.

・ Elastic layer (conductive elastic base layer)
The conductive elastic base layer 2 is formed so as to cover the outer periphery of the conductive support 1. The conductive elastic base layer 2 is made of a conductive elastic body. The conductive elastic body is formed by mixing a conductive agent and a conductive elastic body. The conductive agent contains at least an ionic conductive agent. In particular, epichlorohydrin rubber is preferably used as the conductive elastic body. Epichlorohydrin rubber has some conductivity in the rubber itself, can exhibit good conductivity even with a small amount of conductive agent added, and can also reduce variations in electrical resistance depending on the environment and position. Therefore, it is suitably used as a conductive elastic body.

  Epichlorohydrin rubber is a ring-opening polymer of a cyclic ether centered on epichlorohydrin. Examples of main monomers constituting the rubber include epichlorohydrin, ethylene oxide, and acryl glycidyl ether.

  Examples of the epichlorohydrin rubber that is a polymer include epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer, and the like. 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 conductive elastic body is mainly composed of epichlorohydrin rubber, but may contain other general rubber as required.

  Examples of other general rubbers include EPM (ethylene / propylene rubber), EPDM (ethylene / propylene / diene rubber), norbornene rubber, NBR (nitrile rubber), chloroprene rubber, natural rubber, isoprene rubber, butadiene rubber, and styrene. -Styrene block copolymers such as butadiene rubber, chlorosulfonated polyethylene, urethane rubber, SBS (styrene / butadiene / styrene / block copolymer), SEBS (styrene / ethylene butylene / styrene / block copolymer), and silicone rubber.

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

  As the conductive agent, it is necessary to contain an ionic conductive agent for the purpose of reducing unevenness in electrical resistivity of the conductive elastic base layer. By uniformly dispersing the ionic conductive agent in the conductive elastic body and making the electronic resistivity of the conductive elastic body uniform, uniform charging can be obtained even when the charging roller is used with only DC voltage applied. be able to.

The ion conductive agent, for example, perchlorate such as LiClO ₄ and NaClO _4, include quaternary ammonium salts and the like can be used in combination singly or two or more kinds. Among ionic conductive agents, quaternary ammonium perchlorate is particularly preferably used because of its resistance to environmental changes.

  In addition to the ionic conductive agent, an electronic conductive conductive agent can be added within a range that does not cause unevenness in the electrical resistance of the conductive elastic body. The electroconductive conductive agent can be used in a range in which the electrical conductivity of the electronic conductive agent is smaller than the electrical conductivity of the ionic conductive agent. That is, the electron conductive conductive agent has a volume resistivity when the addition of the electron conductive conductive agent to the volume resistivity when only the ionic conductive agent is added to the conductive elastic body. It can be used at a blending ratio of 2 or more. Examples of the electron conductive conductive agent include metal powders and fibers such as aluminum, palladium, iron, copper, and silver, carbon black, metal powders, metal oxides such as titanium oxide, tin oxide, and zinc oxide, Metal compound powder such as copper sulfide and zinc sulfide, or the surface of appropriate particles tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum, Examples of the powder include rhodium powder deposited by electrolytic treatment, spray coating, and mixed shaking, acetylene black, ketjen black, PAN (polyacrylonitrile) carbon, pitch carbon, and the like. These may be used alone or in combination of two or more.

In the present invention, the blending amount of these conductive agents is such that the volume resistivity of the conductive elastic body is a low temperature and low humidity environment (L / L: 15 ° C./10% RH), a normal temperature and normal humidity environment (N / N: 23 ° C. / 55% RH), in a high-temperature and high-humidity environment (H / H: 30 ° C./80% RH), the amount is such that the middle resistance region (volume resistivity is 1 × 10 ⁴ to 1 × 10 ⁷ Ω · cm). preferable.

  The volume resistance of the conductive elastic body was molded into a sheet having a thickness of 1 mm, and then metal and metal were vapor-deposited on both sides to produce an electrode and a guard electrode. ADVANTEST R8340A ULTRA HIGH RESISTANCE METER Co., Ltd. Advantest A voltage of 200 V is applied using a product, a current after 30 seconds is measured, and the current is calculated from the film thickness and the electrode area.

  If the volume resistivity of the conductive elastic body is smaller than this, if there is a pinhole in the photoconductor that is the image carrier, a large current will be concentrated in the pinhole, making the hole larger. There is a risk that a current may not flow in a place other than the hole and a black band may appear on a high-definition halftone image, and a portion with insufficient charging potential may appear. On the contrary, if the volume resistivity is too large, the applied voltage drops in the conductive elastic layer, and the required discharge current cannot be obtained and the photoreceptor cannot be uniformly charged to a desired potential. is there.

  Other additives such as plasticizers, fillers, vulcanizing agents, vulcanization accelerators, anti-aging agents, scorch preventing agents, dispersants and mold release agents are added to the conductive elastic body as necessary. It is also preferable.

  Examples of the method for forming the conductive elastic body include known methods such as extrusion molding, injection molding, and compression molding by mixing the raw materials for the conductive elastic body. The conductive elastic base layer may be produced by directly forming a conductive elastic body on the conductive support, or by covering the conductive support with a conductive elastic body formed into a tube shape. Also good. The surface may be polished and the shape may be adjusted after the production of the conductive elastic base layer.

  The shape of the conductive elastic base layer is such that the diameter of the central part of the conductive elastic base layer roller is the end so that the contact nip width between the completed charging roller and the photoreceptor is as uniform as possible in the longitudinal distribution of the roller. It is preferable that the crown shape is larger than the diameter. In addition, since the contact roller nip width of the completed roller becomes uniform, it is preferable that the conductive elastic base layer roller has a small runout.

  As shown in FIG. 2, the measured value of run-out is obtained by rotating a conductive elastic base layer roller about a conductive support as a rotation axis, and a non-contact laser length measuring device perpendicular to the rotation axis (in the present invention, a corporation) The difference between the maximum value and the minimum value of the radius of the conductive elastic base layer measured by Keyence LS-5000) is obtained as a value. The difference between the maximum value and the minimum value of the radius is obtained at a pitch of 1 cm in the axial direction of the conductive elastic base layer, and the maximum value among these values is set as the deflection value of the conductive elastic base layer roller.

  Similarly, the diameter of the roller refers to the diameter of the conductive elastic base layer measured by a non-contact laser length meter perpendicular to the rotational axis by rotating the conductive elastic base layer roller about the conductive support as the rotational axis. The average of the maximum and minimum values.

  The difference between the diameter of the central portion in the axial direction of the conductive elastic base layer roller and the average of the two values of the diameter of the central portion 10 mm from both ends of the elastic layer is determined as the value of the crown amount.

  A preferable value of the deflection of the conductive elastic base layer roller is 0.7% or less, more preferably 0.5% or less of the diameter of the central portion of the roller. Since the diameter of the roller of the present invention is preferably about 12 mm, the deflection value is specifically preferably 84 μm or less, more preferably 60 μm or less.

  The value of the crown amount is determined so that the nip width of the finished roller is uniform, but preferably 0.1 to 5.0% of the roller diameter, specifically 12 μm to 600 μm.

  The Asker C hardness of the conductive elastic body is preferably 85 ° or less, and more preferably 80 ° or less. When the Asker C hardness exceeds 85 °, the nip width between the charging member and the photosensitive member is reduced, the contact force between the charging member and the photosensitive member is concentrated in a narrow area, and the contact pressure is increased. As a result, adverse effects such as charging becoming unstable or developer or the like being easily attached to the surface of the photosensitive member or the charging member become remarkable.

  The “Asker C hardness” is the hardness of the charging member measured using an Asker C spring rubber hardness tester (manufactured by Kobunshi Keiki Co., Ltd.) in accordance with the Japan Rubber Association standard SRIS0101. A value measured 30 seconds after the hardness meter is brought into contact with a charging member left in a humid (23 ° C./55% RH) environment for 12 hours or more with a force of 10 N.

  In order to reduce Asker C hardness, a plasticizer is blended in the conductive elastic body. The amount is preferably 1 part by mass or more, more preferably 3 parts by mass or more, relative to 100 parts by mass of the rubber component. As the plasticizer, for example, an ester-based polymer plasticizer such as a copolymer of sebacic acid and propylene glycol can be used. Such ester plasticizers are close in polarity to epichlorohydrin rubber, and can be blended in a relatively large amount, and have an advantage that the hardness of the base layer can be controlled small. The molecular weight of the polymer plasticizer is preferably 2000 or more, more preferably 4000 or more. If the molecular weight is less than 2000, the plasticizer may ooze out on the surface of the roller and contaminate the photoreceptor.

  The conductive elastic base 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, the adhesive may have a known conductive agent.

  Examples of the binder of the adhesive include resins such as thermosetting resins and thermoplastic resins, and known binders such as urethane, acrylic, polyester, polyether, and epoxy can be used.

The conductive agent, for example, perchlorate such as LiClO ₄ and NaClO _4, the ion conductive agent such as quaternary ammonium salts, aluminum, palladium, iron, copper, metal-based powder and fibers such as silver, carbon black , Metal oxide such as metal powder and titanium oxide, tin oxide and zinc oxide, metal compound powder such as copper sulfide and zinc sulfide, or the surface of suitable particles tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, Aluminum, gold, silver, copper, chromium, cobalt, iron, lead, platinum, rhodium, electrolytic powder, powder applied by spray coating, mixed shaking, acetylene black, ketjen black, PAN (polyacrylonitrile) There are carbon powders such as carbon and pitch-based carbon. These may be used alone or in combination of two or more.

・ Outermost layer (surface layer)
After the conductive elastic base layer is completed, a surface layer 3 that covers the outermost surface of the charging roller is provided.

  As a method for forming the surface layer, the materials constituting the surface layer of the above (1) to (5) are prepared by a known method using a conventionally known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, and a pearl mill. The obtained resin coating for forming the surface layer is dispersed and applied on the surface of the charging member, in the present invention, on the conductive elastic base layer by dip coating.

  The film thickness of the surface layer is preferably 1 to 100 μm, more preferably 5 to 60 μm, and still more preferably 8 to 40 μm. When the film thickness of the surface layer is larger than 100 μm, the uniformity of charging is impaired, and fine white stripes are generated in the axial direction of the image upper roller. The film thickness can be measured by cutting the roller cross section with a sharp blade and observing it with an optical microscope or an electron microscope.

  In the present invention, a cross-sectional photograph of 2000 times is taken with a microscope, film thicknesses at five locations are measured randomly in one screen, and the film thickness at one location is calculated by averaging the lengths. This measurement was carried out for a total of 6 points of 3 points in the axial direction and 2 points in the circumferential direction of the same roller, and averaged to obtain the total average film thickness.

  To adjust the surface layer thickness, the solid content of the surface layer paint and the coating pull-up speed are controlled. When the solid content of the resin in the surface coating is increased, the film thickness of the surface layer is increased, and when the solid content is decreased, the film thickness is also decreased. In the surface coating composition of the present invention, the solid content of the resin with respect to the volatile solvent is adjusted to 10 to 40% by mass. Further, when the coating pulling speed is increased, the film thickness is increased, and when the coating pulling speed is decreased, the film thickness is decreased. Therefore, in the present invention, the coating pulling speed is set to 20 to 5000 mm / min. Adjust to. You may apply at the same speed from one end of the roller to the other end of the coating, or considering the sag due to the gravity of the surface paint, increase the coating speed at the upper end of the roller, The coating speed may be continuously reduced as it approaches the lower end.

  As the surface roughness of the charging member of the present invention, preferably the ten-point average roughness Rz according to JIS B0601-1994 is 0.5 μm to 40 μm, Ra is 0.1 μm to 5 μm, more preferably the ten-point average roughness. Rz is 1 μm or more and 30 μm or less, and Ra is 0.4 μm or more and 6 μm or less. If the surface roughness is too large, uneven charging tends to appear in the output image, and if the surface roughness is too small, the effect of stabilizing the charging at a slow process speed by adding resin particles is not preferable.

  As a measuring method of average roughness (Ra, Rz), based on the surface roughness of JIS B0601, surf coder SE3400 manufactured by Kosaka Laboratories was used to measure a total of 6 points, 3 in the axial direction and 2 in the circumferential direction. , Take the average value. In the present invention, the contact needle is a diamond having a tip radius of 2 μm, a measurement speed of 0.5 mm / s, a cutoff λc of 0.8 mm, a reference length of 0.8 mm, and an evaluation length of 8.0 mm.

  In order to obtain a charging member having a surface roughness in the above range, the surface roughness of the elastic base layer, the film thickness of the surface layer, the average particle diameter of the resin particles, and the addition amount are adjusted. The ten-point average roughness of the elastic base layer is 20 μm or less, more preferably 15 μm or less in terms of Rz.

Further, as shown in FIGS. 6A and 6B, the charging member of the present invention has the same curvature as that of the photosensitive member with the same stress as that in the usage state when used in the electrophotographic apparatus. While contacting the columnar metal 32 and rotating the columnar metal at the same rotational speed as in use (in the present invention, a force of 5 N is applied to both ends of the support 1 from the pressing tools 33a and 33b, respectively, The electrical resistance of the charging member is 30 ° C./80% RH when a DC voltage of −200 V is applied from the power source 34. The metal member is brought into contact with a 30 mm metal cylinder and rotated at a peripheral speed of 45 mm / s. It is preferably 1 × 10 ⁴ Ω or more in a high temperature and high humidity environment, and 1 × 10 ⁸ Ω or less in a low temperature and low humidity environment of 15 ° C./10% RH. More preferably, it is 2 × 10 ⁴ Ω or more in a high temperature and high humidity environment of 30 ° C./80% RH, and 6 × 10 ⁷ Ω or less in a low temperature and low humidity environment of 15 ° C./10% RH. . Reference numeral 35 denotes an ammeter.

  It is preferable that the resistance in a low-temperature and low-humidity environment is smaller than the above range because fine horizontal white lines on the halftone image due to charging unevenness hardly occur. Further, it is preferable that the resistance in a high-temperature and high-humidity environment is larger than the above range because even if there is a pinhole in the photoconductor, the applied current does not leak and the uneven density of charging does not appear on the halftone image.

In order to make the electric resistance within the above range, the volume resistivity of the conductive elastic base layer of the charging member is 1 × 10 ³ to 1 × 10 ⁷ Ω · cm, and the volume resistivity of the surface layer is 1 × 10 ⁸ to 1 What is necessary is just to adjust so that it may be x10 < ¹⁵ > (omega | ohm) * cm and the film thickness of a surface layer may be 10-50 micrometers.

<Electrophotographic device>
FIG. 3 is a schematic sectional view of an electrophotographic apparatus using a charging roller 6 which is an embodiment of the charging member according to the present invention. The photosensitive drum 5 as an image carrier is primarily charged by the charging roller 6 while rotating in the direction of the arrow, and then exposed to exposure 11 by the exposure means to form an electrostatic latent image. The toner in a thin layer on the developing roller 4 as developing means is charged by the toner charging roller 29 and then brought into contact with the surface of the photosensitive drum 5 to develop the electrostatic latent image and visualize the toner image. Is formed.

  The developed toner image is transferred from the photosensitive drum 5 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 5, and then heated and fixed by the fixing portion 9. It is fixed by pressure and becomes a permanent image. The latent image remaining on the photosensitive drum is exposed by a pre-charge exposure device (not shown), and the potential of the photosensitive drum 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 4, the toner charging roller 29, the charging roller 6, and the transfer roller 8 from power sources 18, 19, 20, and 22 of the electrophotographic apparatus. 28 is a toner conveying roller, 30 is an elastic regulating blade, and 31 is a toner container.

  Here, a DC voltage is applied from the power source 20 to the charging roller 6 which is the charging member of the present invention. By using a DC voltage as the applied voltage, there is an advantage that the cost of the power supply can be kept low. In addition, there is an advantage that no charging noise is generated when an AC voltage is applied.

  The absolute value of the DC voltage to be applied is preferably 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). Usually, the discharge start voltage of air is about 600 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 900 to 1500 V.

  In the case of a full-color electrophotographic apparatus, as shown in FIG. 4, the photosensitive drums 5a to 5d, the transfer rollers 8a to 8d, the charging rollers 6a to 6d, the toner charging rollers 29a to 29d, the elastic regulation blades 30a to 30d, the exposure. 11a to 11d, toner containers 31a to 31d, and the like may be prepared for each of four colors and arranged in series.

<Process cartridge>
As shown in FIG. 5, the process cartridge according to the present invention transfers a toner to an electrostatic latent image formed on the image bearing member 5 and an electrostatic latent image formed on the image bearing member to visualize the toner image. One selected from developing means including a developing roller 4 to be formed, and cleaning means including a cleaning blade 10 that removes toner remaining on the image carrier after a toner image is transferred to the transfer member, or Two or more are supported by the casing integrally with the charging member 6 according to the present invention, and are configured to be detachable from the main body of the electrophotographic apparatus.

  Before the process cartridge is used, it is preferable to avoid contact between the developing roller 4 and the toner with the toner seal 27.

  The present invention will be described below with reference to examples, but the present invention is not limited to the examples.

Example 1
<Production of charging roller>
(1) Creation of elastic layer (conductive elastic base layer) Epichlorohydrin rubber (trade name: Epichromer CG102, manufactured by Daiso Corporation) 100 parts by mass, calcium carbonate 30 parts by mass as filler, zinc stearate 1 as lubricant 4 parts by mass, 4 parts by mass of colored grade carbon (trade name: Seest SO, manufactured by Tokai Carbon Co., Ltd.), 5 parts by mass of zinc oxide as plasticizer, and sebacic acid and propylene glycol as plasticizers 5 parts by mass of a copolymer (molecular weight 8000), 2 parts by mass of a quaternary ammonium perchlorate salt of the following formula,

1 part by mass of 2-mercaptobenzimidazole as an anti-aging agent is kneaded with an open roll for 20 minutes, further 1 part by mass of DM (2-benzothiazolyl disulfide) as a vulcanization accelerator, and as a vulcanization accelerator 0.5 parts by mass of TS (tetramethylthiuram monosulfide) and 1.2 parts by mass of sulfur as a vulcanizing agent were added and further kneaded with an open roll for 15 minutes.

  This was extruded into a cylindrical shape with an outer diameter of 14 mm and an inner diameter of 5.5 mm using a rubber extruder, cut into a length of 250 mm, and primary-vulcanized in steam at 160 ° C. for 40 minutes using a vulcanizing can. Sulfurized to obtain a primary vulcanization tube of conductive elastic base layer rubber.

  Next, a thermosetting adhesive of metal and rubber (trade name: product name: 231 mm in the axial central portion of the cylindrical surface of a cylindrical conductive support (made of steel, surface is nickel-plated) having a diameter of 6 mm and a length of 256 mm. Metallock U-20) was applied, dried at 80 ° C. for 30 minutes, and then dried at 120 ° C. for 1 hour. This conductive support was inserted into the conductive elastic base layer rubber primary vulcanization tube, then subjected to secondary vulcanization and curing of the adhesive in an electric oven at 160 ° C. for 2 hours to form an unpolished layer. Obtained.

  After cutting off both ends of the rubber part of this unpolished layer and setting the length of the rubber part to 231 mm, the rubber part is polished with a rotating grindstone to form a crown shape with an end diameter of 11.90 mm and a central part diameter of 12.00 mm. A charging roller having a conductive elastic base layer having a surface ten-point average roughness Rz of 6 μm and a deflection of 25 μm was obtained.

When the charging roller having the conductive elastic base layer was measured after the charging roller having the conductive elastic base layer was left in an N / N (normal temperature and normal humidity: 23 ° C./55% RH) environment for 24 hours or more, the resistance of the charging roller having the conductive elastic base layer was measured. It was 3.0 × 10 ⁵ Ω. The Asker C hardness of the rubber part was 74 °.

(2) Creation of outermost layer (surface layer) For 100 parts by mass of silica powder (Reoseal QS-10, manufactured by Tokuyama Corporation), 1 part by mass of dimethyldimethoxysilane was added to Mechano Micros (manufactured by Nara Manufacturing Co., Ltd.). Was introduced while operating at a vessel rotational speed of 200 rpm and a rotor rotational speed of 2000 rpm, and kneaded for 15 minutes while maintaining 70 ° C. Next, 100 parts by mass of carbon black MA100 (volatile content 1.5% by mass, manufactured by Mitsubishi Chemical Corporation) as a conductive agent was added to 100 parts by mass of silica powder, and kneaded for 100 minutes while maintaining 70 ° C. The resulting composite conductive particles specific surface area of 140m ² / g, DBP oil absorption amount was 90cm ^3/100 g.

  1056 parts by mass of lactone-modified acrylic polyol (trade name: Plaxel DC2016, manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 2304 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solution having a solid content of 22% by mass. With respect to 200 parts by mass of the acrylic polyol solution, 5.72 parts by mass of the composite conductive particles, 0.08 parts by mass of silicone oil (trade name: SH-28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.), isophorone diisocyanate 11.79 parts by mass of block type isocyanurate type trimer (trade name: Bestanat B1370, manufactured by Degussa Huls), isocyanurate type trimer of hexamethylene diisocyanate (trade name: Duranate TPA-B80E, Asahi Kasei Kogyo Co., Ltd.) was mixed at a ratio of 7.54 parts by mass and copper phthalocyanine at a ratio of 0.5 parts by mass.

  30 liters of the above blended solution was placed in a stainless steel cylindrical container having a diameter of 30 cm, and the stirring blade was rotated at 300 rpm and stirred for 30 minutes. 30 liters of this dispersion was circulated and dispersed in a 2 liter horizontal bead mill filled with 80% φ0.8 mm glass beads. It was dispersed for 8 hours while rotating at a peripheral speed of 8 mm / s, a circulation rate of 2 liters / minute, and a temperature of the outer wall of the mill of 22 ° C. Thereafter, crosslinked polymethyl methacrylate (trade name: MBX-5, manufactured by Sekisui Plastics Co., Ltd.) having an average particle size of 5 μm was placed in a circulating bead mill tank at 30. parts by mass with respect to 200 parts by mass of the acrylic polyol solution. The mixture was blended to 8 parts by mass, and further dispersed for 4 hours while rotating at a peripheral speed of 3 mm / s, a circulation rate of 2 liters / minute, and a temperature of the outer wall of the mill of 22 ° C. After dispersion, the liquid was taken out and the viscosity was measured. The viscosity of the paint was 8.5 mPa · s in an environment of 23 ° C.

  When this paint is put into a coating tank for dip coating and circulated slowly for 24 hours and the paint is stabilized, the surface layer paint is applied to the surface of the conductive elastic base layer by dip coating at a speed of 300 mm / min. did. After air-drying for 15 minutes, the axial direction during roller application was subsequently reversed, and coating was performed in the same manner as in the first coating. After air-drying again for 30 minutes, it was dried in an oven at 80 ° C. for 30 minutes, and then dried in an oven at 160 ° C. for 60 minutes.

  A surface layer having a uniform film thickness of 20 μm was formed on the obtained charging roller over the entire image area of the roller. The completed roller was used as the charging roller of Example 1A.

  Next, the coating solution was slowly circulated in the coating tank as it was for 7 days, and a charging roller was coated in the same procedure as in Example 1A. The completed roller was used as the charging roller of Example 1B.

<Evaluation of surface paint>
After preparing the paint, put the obtained paint into a 10 ml sample bottle to a depth of 30 mm and let it stand, and after 24 hours, 7 days have passed, the amount of sedimentation of the composite conductive particles by leaving each (bottom surface) (Deposition height from).

  The coating liquid of Example 1 had a deposit height of 2.0 mm after 24 hours and 3.0 mm after 7 days.

<Evaluation of charging roller>
・ Measurement of charging roller resistance Using the coating liquid circulated in the coating tank for 24 hours after the paint was created and the coating liquid circulated in the coating tank for 7 days after the paint was created. Each charging roller was prepared, resistance was measured in a normal temperature and normal humidity environment (N / N: 23 ° C./55% RH), and the ratio was evaluated (circulation for 24 hours / circulation for 7 days).

When resistance measurement was performed on the charging roller of Example 1A and the charging roller of Example 1B, the resistance was both 1.6 × 10 ⁵ Ω, and there was no change in resistance over time after the coating liquid was prepared.

Image Evaluation The electrophotographic laser printer used in this test is an A4 vertical output machine, the recording medium output speed is 190 mm / sec, and the image resolution is 600 dpi.

  The photoreceptor is a reversal development type photosensitive drum in which an organic photosensitive layer (OPC layer) having a film thickness of 16 μm is coated on an aluminum cylinder, and the outermost layer is a charge transport layer using a modified polyarylate resin as a binder resin.

  The toner is made by polymerizing a random copolymer of styrene and butyl acrylate containing a charge control agent, a pigment and the like with a wax at the center, further polymerizing a polyester thin layer on the surface, and externally adding silica fine particles, a glass transition temperature of 63 ° C., It is a polymerized toner having a mass average particle diameter of 6.5 μm.

  For primary charging, a DC voltage of −1150 V was applied to the charging roller. The surface potential of the photoreceptor was -650V. The surface potential of the photosensitive member when irradiated with a laser with such intensity that a solid image having the maximum density was output was -150V.

  Next, the charging roller according to this example was incorporated into an electrophotographic apparatus and brought into contact with a new photoreceptor, and an initial image was output in an environment of normal temperature and humidity (23 ° C./55% RH). When a halftone image (image when irradiated with laser light with a reduced output so that the photoreceptor surface potential is −400 V) is output, a very uniform and good image is obtained without any horizontal white stripes. It was.

(Examples 2 to 7)
A charging roller of Example 2A and Example 2B was obtained in the same manner as Example 1 except that zinc phthalocyanine was used instead of copper phthalocyanine.

  A charging roller of Example 3A and Example 3B was obtained in the same manner as Example 1 except that iron phthalocyanine was used instead of copper phthalocyanine.

  Charge rollers of Example 4A and Example 4B were obtained in the same manner as in Example 1 except that magnesium phthalocyanine was used instead of copper phthalocyanine.

  A charging roller of Example 5A and Example 5B was obtained in the same manner as in Example 1 except that oxytitanium phthalocyanine was used instead of copper phthalocyanine.

  The charging rollers of Examples 6A and 6B were obtained in the same manner as in Example 1 except that chlorogallium phthalocyanine was used instead of copper phthalocyanine.

  The charging rollers of Examples 7A and 7B were obtained in the same manner as in Example 1 except that aluminum chlorophthalocyanine was used instead of copper phthalocyanine.

  When the images of the charging rollers of Examples 2A to 7A and Examples 2B to 7B were evaluated, no horizontal white streaks were generated at all and very good images were obtained. Further, the ratio of the roller resistance was as very small as 1.0 times to 1.1 times, and the change in the surface layer paint over time was very small. Further, the solution was put in a small bottle and the state of precipitation was observed. Even after 7 days, the precipitation of all the surface layer paints was 3 mm or less, and the precipitation was very small.

(Example 8)
The charging rollers of Examples 8A and 8B were obtained in the same manner as in Example 1 except that the amount of copper phthalocyanine added was reduced from 0.5 parts by mass to 0.01 parts by mass.

  As a result of image evaluation, the image of the roller of Example 8A was very good, but the image of the roller of Example 8B had horizontal white streaks, but it was of an acceptable level for practical use. Further, the roller resistance ratio was 2.0 times, and although the surface layer paint was changed, it was an acceptable level. Furthermore, when the solution was put in a small bottle and the state of precipitation was observed, the amount of precipitation was 3.5 mm after 24 hours and 5.0 mm after 7 days.

Example 9
The charging rollers of Examples 9A and 9B were obtained in the same manner as in Example 1 except that the amount of copper phthalocyanine added was reduced from 0.5 parts by mass to 0.05 parts by mass.

  As a result of the image evaluation, the image of the roller of Example 9A was very good, but the image of the roller of Example 9B had a slight horizontal white streak, but at a level that was not noticeable in practice. Further, the roller resistance ratio was 1.6 times, and although the surface layer paint was slightly changed, it was an acceptable level. Furthermore, when the solution was put in a small bottle and the state of precipitation was observed, it was 2.5 mm after 24 hours and 4.0 mm after 7 days.

(Example 10)
With respect to Example 1, the amount of copper phthalocyanine added was increased from 0.5 parts by mass to 5.0 parts by mass to obtain charging rollers of Example 10A and Example 10B. Since the resistance of the charging roller becomes too large only by increasing the copper phthalocyanine, the composition of the composite conductive particles was increased from 5.72 parts by mass to 6.6 parts by mass to obtain a surface coating material and a charging roller.

  As a result of image evaluation, no horizontal white streaks occurred at all in the charging rollers of Example 10A and Example 10B, and very good images were obtained. Further, the ratio of the roller resistance was as very small as 1.0 times, and the change of the surface layer paint with time was very small. Further, the solution was put in a small bottle and the state of precipitation was observed. Even after 7 days, the precipitation of all the surface layer coatings was 2.5 mm or less, and the precipitation was very small.

(Example 11)
With respect to Example 1, the amount of copper phthalocyanine added was significantly increased from 0.5 parts by mass to 50 parts by mass to obtain charging rollers of Example 11A and Example 11B. Since the resistance of the charging roller becomes too large only by increasing the copper phthalocyanine, the composition of the composite conductive particles was increased from 5.72 parts by mass to 13.2 parts by mass to obtain a surface coating material and a charging roller.

  As a result of image evaluation, no horizontal white streaks occurred in the charging rollers of Example 11A and Example 11B, and very good images were obtained. Further, the ratio of the roller resistance was as very small as 1.0 times, and the change of the surface layer paint with time was very small. Furthermore, the solution was put in a small bottle and the state of precipitation was observed. Even after 7 days, the precipitation of all the surface layer paints was 2.0 mm or less, and the precipitation was very small.

(Example 12)
The charging rollers of Examples 12A and 12B were obtained in the same manner as in Example 1 except that spherical crosslinked polystyrene resin particles having an average particle diameter of 5 μm were used instead of the polymethyl methacrylate resin particles.

  As a result of image evaluation, no horizontal white streaks occurred in the charging rollers of Example 12A and Example 12B, and very good images were obtained. Further, the ratio of the roller resistance was as very small as 1.0 times, and the change of the surface layer paint with time was very small. Furthermore, the solution was put in a small bottle and the state of precipitation was observed. Even after 7 days, the precipitation of all the surface layer paints was 3.0 mm or less, and the precipitation was very small.

(Comparative Example 1)
With respect to Example 1, the amount of copper phthalocyanine added was reduced from 0.5 parts by mass to zero added to obtain charging rollers of Comparative Example 1A and Comparative Example 1B. When the addition of copper phthalocyanine is stopped, the resistance of the charging roller becomes too small. Therefore, the composite conductive particle content was reduced from 5.72 parts by mass to 5.5 parts by mass to obtain a surface coating material and a charging roller.

  As a result of the image evaluation, the image of the roller of Comparative Example 1A was very good, but a large amount of horizontal white streaks occurred in the image of the roller of Comparative Example 1B, which was at a level that could not be put into practical use. Further, the ratio of the roller resistance was 11.3 times, and it was found that the resistance of the roller rapidly decreased due to the change of the surface layer paint over time. Further, when the solution was put in a small bottle and the state of precipitation was observed, it was 4.5 mm after 24 hours and 7.0 mm after 7 days. I found out.

(Comparative Example 2)
A charging roller of Comparative Example 2A and Comparative Example 2B was obtained in the same manner as in Example 1 except that the conductive agent added in Example 1 was eliminated.

  As a result of the image evaluation, both of the rollers of Comparative Example 2A and Comparative Example 2B were extremely intense and a large amount of horizontal white streaks were generated on the image, which was at a level unbearable for practical use. From the beginning, the conductivity required as a charging roller has not been obtained. Further, when the solution was put in a small bottle and the state of precipitation was observed, it was 5.0 mm after 24 hours and 6.0 mm after 7 days. Was sinking.

  Tables 1 and 2 collectively show the composition of the above Examples and Comparative Examples, and the results of image output and sedimentation amount.

<Initial image>
◎: Very good image with no horizontal white stripes ○: Slight white horizontal stripes are seen, but an image of a level that is not noticeable in practice △: Horizontal white stripes are seen, but practically acceptable Image x: Image with intense horizontal white lines

(A) is sectional drawing of the direction orthogonal to the electroconductive support body of the charging roller which concerns on this invention, (b) is sectional drawing of the direction in alignment with the electroconductive support body of the charging roller which concerns on this invention. (A) is a schematic perspective view of the measuring apparatus of the deflection | deviation of the electroconductive elastic body base layer roller which comprises a charging roller, (b) is a schematic sectional drawing of (a). 1 is a schematic cross-sectional view of one embodiment of an electrophotographic apparatus according to the present invention. It is a schematic sectional drawing of the other aspect of the electrophotographic apparatus which concerns on this invention. It is a schematic sectional drawing of the process cartridge which concerns on this invention. It is a schematic explanatory drawing of the measuring method of the surface roughness of the charging member which concerns on this invention.

Explanation of symbols

1 Conductive Support 2 Elastic Layer (Conductive Elastic Base Layer)
3 Outermost layer (surface layer)
4 Developing roller 5, 5a to d Photosensitive drum 6, 6a to d Charging roller 7 Print medium 8, 8a to d Transfer roller 9 Fixing portion 10 Cleaning blade 11, 11a to d Exposure light 18, 19, 20, 22 Power supply 27 Toner seal 28 Toner transport roller 29, 29a to d Toner charging roller 30, 30a to d Elastic regulating blade 31 Toner container 32 Columnar metal 33a, 33b Pressing tool 34 Power supply 35 Ammeter

Claims (10)

  A charging member characterized in that the outermost layer contains at least conductive fine particles and a phthalocyanine compound.   The charging member according to claim 1, wherein the conductive fine particles are carbon black, graphite, or composite conductive particles containing carbon black or graphite.   The charging member according to claim 2, wherein the composite conductive particles are composite conductive particles obtained by binding insulating fine particles and carbon black or graphite.   The charging member according to claim 3, wherein the insulating fine particles are any one of silica, alumina, and titania.   The charging member according to claim 1, wherein the outermost layer contains crosslinked resin particles.   The charging member according to claim 1, wherein the outermost layer contains insulating inorganic fine particles.   The charging member according to claim 1, comprising two or more kinds of insulating inorganic fine particles.   The charging member according to claim 1, further comprising a conductive elastic layer and a conductive support below the outermost layer.   An electrophotographic apparatus comprising a charging member containing at least conductive fine particles and a phthalocyanine compound as an outermost layer.   A process cartridge for an electrophotographic apparatus, wherein a charging member containing at least conductive fine particles and a phthalocyanine compound is used as an outermost layer.