JP2003057903A - Conductive member, process cartridge, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive member which can actualize an invariable excellent image when built in an electrophotographic device. SOLUTION: The conductive member is formed by laminating at least an elastic resistance layer 7 and a coating layer 8 on a conductive base body 5 in this order and the coating layer includes two or more kinds of conductive materials having different volume resistivity values; and the volume resistivity value of a conductive material (A) having the relatively small volume resistivity value is >=1×10<-1> Ωcm and <=1×10<5> Ωcm, the volume resistivity value of a conductive material (B) having the relatively large volume resistivity value is 2×10<1> to 1×10<5> Ωcm, and the mass ratio (Mb/Ma) of the mixing amount (Mb) of the conductive material (B) to the mixing amount (Ma) of the conductive material (A) is 1/3 to 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging roller used in an electrophotographic apparatus such as a copying machine or a laser printer,
The present invention relates to a conductive member such as a developing roller, a process cartridge, and an image forming apparatus.

[0002]

2. Description of the Related Art In a conventional electrophotographic apparatus, a charging device for uniformly charging the surface of a photosensitive member and a transferable toner image formed on the surface of the photosensitive member are transferred to a sheet-like transfer material mainly composed of paper. As a transfer device for electrostatic transfer, a corona charger using a corona discharge generated by applying a high voltage to a thin wire such as tungsten and the like is generally used. However, this method using corona discharge requires a high-voltage power source and may cause adverse effects such as deterioration of the photoconductor due to strong oxidizing action of ozone generated.

For this reason, many ozoneless charging and ozoneless transfer methods have been proposed in the past. However, these methods mainly supply charges to a photosensitive member, which is a member to be charged, directly from a conductive charging member or a transfer member. As a result, the discharge current was reduced as much as possible, and as a result, the amount of ozone generated during discharge was reduced. The ozoneless charging modes are briefly classified into, for example, a method using an elastic roller, a method using a fur brush, and a method using a solid discharge element for the charging member. Regarding the method of forming the discharge electric field, there are a method of applying a DC voltage to the charging member and a method of simultaneously applying an AC voltage and a DC voltage.

As a structure of such a conductive member, at least two or more resistance layers are provided on a conductive substrate, and the lower resistance layer has a proper nip width with a surface to be charged or a transfer target. Maintains proper elasticity. The resistance layer is formed by adding a softening agent such as oil or a plasticizer to an elastic body such as rubber or resin. However, since these softening agents generally have migration property, they may contaminate the photoreceptor. Therefore, it is necessary to apply a coating layer if necessary.

Regarding the resistance constitution of the conductive elastic body and the coating layer, when the conductive member is, for example, a charging member,
In general, if the volume resistance of the charging member is too high, an irregular image in which white and black spots are scattered on a solid white or halftone image, which is generally called sand, may occur due to uneven charging or poor charging of the photoreceptor. On the other hand, if it is too low, the upper layer will have a lower withstand voltage, or if a pinhole is generated on the surface of the photoconductor due to manufacturing or handling, etc., an abnormal diamond shape will occur on the image corresponding to the pinhole during reversal development. Images may occur. Therefore, there is an appropriate area for the resistance of the charging member.

Therefore, in order to adjust the resistance of the charging member, a conductive material such as conductive carbon black is dispersed in a polymer material such as acryl, urethane, acryl urethane, hydrin or nylon for the coating layer to provide an appropriate resistance. Attempts have been made to hold the same and to prevent the charging uniformity of the member to be charged, the prevention of pinholes on the surface of the member to be charged such as a photoconductor, and the leakage due to scratches.

[0007]

However, the relationship between the amount of addition of a conductive material having a small volume resistivity to the material forming the coating layer and the resistance of the coating layer is that the resistance value increases as the amount added increases. Although it has a decreasing relationship, the rate of change in resistance is large. Particularly, the electric resistance value of 1 × 10 ⁵ which is required for a conductive member such as a charging member, a developing member and a transfer member.
In the medium resistance region of about 1 × 10 ¹⁰ Ω, the rate of change of the resistance value of the coating layer is generally very large with respect to the amount of the conductive material having a small volume specific resistance value added. For this reason, there are cases where it is very difficult to stabilize the quality during mass production, for example, it is necessary to weigh and add a small amount of a conductive material very accurately.

Further, since the resistance value of the conductive member is controlled to a desired resistance value by adding a small amount of the conductive material, the existence of the conductive material is thin, so that the high-definition of the electrophotographic apparatus is high. In some cases, it is not possible to satisfy the uniformity of charging that can cope with the increase in charge, and an abnormal image due to poor charging, which is generally referred to as sand, may occur, and in addition, leak resistance may not be sufficiently improved.

On the other hand, in the case of controlling the resistance value of the conductive member by adding a large amount of conductive material having a large volume specific resistance value, a large amount of conductive material must be added as compared with the material forming the coating layer. As a result, there are problems to be solved, such as deterioration of the film characteristics, which may lead to problems during long-term use of the conductive member.

As a conventional technique, in a conductive member in a semiconductive region such as a conductive member to which the present invention is applied, in order to adjust the resistance and make the resistance uniform, Japanese Patent Publication No. 8-007.
No. 485, the powder resistance is 10 ¹ to 10 ⁵ Ωcm.
It is described that the hardness of the coating layer in which the conductive particles are dispersed is adjusted to a Shore D hardness of 50 to 100. However, in the range of the powder resistance value of the conductive material, in order to reduce the resistance value of the coating layer, a large amount of the conductive material must be dispersed, which may deteriorate the film strength. It was

The conductive particles used for achieving the resistance value in the semi-conductive region, which is required for the conductive member such as the charging member, are not always produced industrially and stably.
Therefore, even when available, it can be very expensive. Further, even when the resistance of the coating layer is adjusted by dispersing these conductive particles in an appropriate amount and the hardness of the coating layer is adjusted as described above, charging failure such as charging failure may occur depending on the type of the coating layer material and the adjusting method. There was a case where the image adverse effect occurred.

Therefore, in order to realize a predetermined resistance value as a conductive member, Japanese Patent Laid-Open No. 8-208995 discloses
It has been attempted to adjust the electrical resistance of the conductive member by mixing ¹ to 10% of conductive carbon and 10 ¹ to 10 ⁸ Ωcm of a conductive filler other than the conductive carbon at a ratio of 90 to 99%. . However, just by mixing two kinds of conductive materials having different volume specific resistance values in this way, it is considered that charging failure such as non-uniformity of the dispersed form of the conductive material due to the kind of the material of the coating layer and the adjustment method. There was a case where the bad effect of the image occurred.

Therefore, the present invention provides a conductive member having stable electric characteristics so that a good image can always be obtained even when incorporated in an electrophotographic apparatus as described above. To aim.

[0014]

According to the present invention for achieving the above object, at least in a conductive member in which an elastic resistance layer and a coating layer are laminated in this order on a conductive substrate, the coating is performed. The layer contains two or more kinds of conductive materials having different volume specific resistance values, and the volume specific resistance value (Ra) of the conductive material (A) having a small volume specific resistance value is 1 × 10 ^−1.
Ωcm or more and 5 × 10 ³ Ωcm or less, the volume specific resistance value (Rb) of the conductive material (B) having a large volume specific resistance value is 2 × 10 ¹ Ωcm or more and 1 × 10 ⁵ Ωcm or less, and the conductive material ( The mass ratio (Mb / Ma) of the blending amount (Mb) of the conductive material (B) to the blending amount (Ma) of A) is 1
Provided is a conductive member having a thickness of / 3 or more and 15 or less.

The conductive member as described above is preferably arranged in a process cartridge which is detachably attached to the main body of the image forming apparatus.

The conductive member as described above is suitably arranged in an image forming apparatus such as an electrophotographic apparatus as a member such as a charging roller and a transfer roller.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in a conductive member having a coating layer containing two or more kinds of conductive materials having different volume specific resistance values, the volume specific resistance value is 2 × 10 ¹ Ω.
cm or more and 1 × 10 ⁵ Ωcm or less, the volume resistivity of the conductive material (B) having a relatively large volume resistivity of 1 × 10 ⁻¹ Ωcm or more and 5 × 10 ³ Ωcm or less Is 1/3 times or more and 15 times or less by mass ratio with respect to the conductive material (A) which is relatively small.

When the mass ratio is 1/3 or more, the influence of the conductive material (A) having a small volume specific resistance value is moderate, and the change in the electric resistance value of the coating layer with respect to the blending amount is small. From such a viewpoint, it is more preferable that Mb / Ma is 1 or more. On the other hand, when the mass ratio is 15 times or less, since the amount of the conductive material (B) having a large volume resistivity value is appropriate, deterioration of the film characteristics of the coating layer is suppressed.

By setting the mass ratio to 1/3 times or more and 15 times or less, the conductive material (A) having a relatively small volume specific resistance value.
A large amount of the conductive material (B) having a relatively large volume specific resistance value is present in the vicinity of the, and as a result, the coating layer of the coating layer with respect to the compounding amount of the conductive material (A) having a relatively small volume specific resistance value is present. The rate of change of the electric resistance value can be suppressed to be small.

Further, as compared with the case where the conductive material (B) having a large volume specific resistance value is mixed only with the conductive material having a small volume specific resistance value, the coating layer is larger than the total amount of the conductive material present. The resistance value of can be increased.

Further, by mixing the electric resistance value which cannot be achieved only by the conductive material (B) having a relatively large volume specific resistance value with the conductive material having a small volume specific resistance value, it is realized without deteriorating the film characteristics. it can.

As a result, it is possible to provide a conductive member having excellent leak characteristics and the like, and it is possible to suppress deterioration of the film characteristics.

From the above viewpoint, the compounding amount of the conductive material (A) is 100 parts by mass with respect to 100 parts by mass of the resin contained in the coating layer.
The amount of the conductive material (B) to be blended is preferably 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the resin contained in the coating layer.

The volume resistivity value can be measured, for example, by the tablet method. That is, a volume specific resistance value can be calculated by applying a voltage of 100 V to the powder sample under a load of 9.8 MPa, measuring the resistance value, and normalizing.

The average particle size (Da) of the conductive material (A) having a relatively small volume specific resistance value is 70 nm or less, and the average particle size of the conductive material (B) having a relatively large volume specific resistance value. (Db) is preferably 100 nm or less.

In this case, a relatively large amount of the electrically conductive material (B) having a relatively large volume specific resistance value is surrounded by the electrically conductive material (A) having a relatively small volume specific resistance value. It is possible to suppress the local variation in the resistance value of the conductive member due to the uneven distribution of the small conductive material (A), and to make the resistance value uniform.

On the other hand, the average particle diameter (Da) of the conductive material (A) having a relatively small volume specific resistance value and the average particle diameter (Db) of the conductive material (B) having a relatively large volume specific resistance value.
Is generally 10 nm or more.

The average particle size of the conductive material can be observed by an electron microscope or the like, and when a coating layer is prepared by coating with a paint, the solution is measured by a laser diffraction type particle size distribution measuring device or a centrifugal type particle size distribution measuring device. Can be measured by Further, the conductive material having a desired average particle diameter can be prepared by a method such as a sphere separation method.

Further, the ratio (Rb / Ra) of the volume specific resistance value (Rb) of the conductive material (B) to the volume specific resistance value (Ra) of the conductive material (A) is larger than 1 and 1 × 1.
It is more preferably 0 ² or more, and more preferably 3 × 10 ⁴ or less. In this case, the electric resistance value of the conductive member can be adjusted more easily.

The present invention will be described below with reference to the drawings.

FIG. 1 shows a roller-shaped charging member as an example of one embodiment of the conductive member of the present invention. Reference numeral 5 is a core metal which is a conductive substrate, 7 is an elastic resistance layer, and 8 is a coating layer.

Further, FIG. 3 shows a state in which the charging member 2 made of a conductive member of the present invention and the photosensitive drum 10 are brought into contact with each other to form the nip portion 13 in the process cartridge.

The charging member 2 has a structure in which a conductive base 5 is covered with a resistor 6, and the conductive base 5 is connected to a power supply 3. The resistor 6 has a two-layer structure including a cover layer 8 as an outermost surface layer and an elastic resistance layer 7. Further, the photosensitive drum 1 which is a drum-shaped electrophotographic photosensitive member
0 has a structure in which a photoconductor 12 made of OPC, amorphous silicon, selenium, zinc oxide or the like is provided on a drum base 11 which is grounded so as to be rotatable in the R direction.

(Coating layer) The coating layer contains a conductive material (A) and a conductive material (B), and contains a resin as a matrix of these conductive materials. Conductive material (A)
The conductive material (B) is not particularly limited except for the volume resistivity, but in view of dispersibility in the coating layer, titanium oxide, tin oxide, zinc oxide, indium oxide,
Tin oxide, tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum;
It is also preferable to deposit gold, silver, iron, copper, chromium, cobalt, lead, platinum, rhodium or the like by electrolytic treatment, spray coating, mixed shaking tow or the like. Alternatively, conductive particles in which a conductive polymer such as aniline is provided on the surface of beads such as nylon may be used.

Among the above, at least one of the conductive material (A) and the conductive material (B) is preferably a solid solution of a metal oxide for the reason that good dispersibility and uniform charging can be realized. Further, it is more preferable that both the conductive material (A) and the conductive material (B) are solid solutions of metal oxides.

Among them, the conductive particles containing tin oxide, zinc oxide, indium oxide, or tin oxide as the main component are particularly preferable because the medium resistance region in the present invention can be stably controlled by the amount of the dopant.

A resin or a rubber material is used as the resin. As the resin used for the coating layer, for example, polyurethane, polymethyl methacrylate, acrylic resin such as polybutyl methacrylate, polyvinyl butyral, polyvinyl acetal, polyarylate, polycarbonate,
Examples thereof include polyester, phenoxy resin, polyvinyl acetate, polyamide, polyvinyl pyridine, and cellulosic resin.

As the rubber material, for example, EPD
M, polybutadiene, natural rubber, polyisoprene, SB
Rubbers such as R (styrene butadiene rubber), CR (chloroprene rubber), NBR (nitrile butadiene rubber), silicone rubber, urethane rubber, epichlorohydrin rubber, RB (butadiene resin), SBS (styrene-butadiene-styrene elastomer), etc. Polystyrene-based,
Polyolefin type, polyester type, polyurethane, P
E (polyethylene), PP (polypropylene), PVC
A resin material such as (polyvinyl chloride), an acrylic resin, a styrene-vinyl acetate copolymer, a butadiene-acrylonitrile copolymer can be used.

A predetermined amount of a predetermined conductive material is dispersed in the resin as described above. As a dispersing means, a roll kneader, a Banbury mixer, a ball mill, a sand grinder,
A paint shaker or the like may be used as appropriate. In addition, if necessary, an appropriate dopant or the like may be added to adjust the electric resistance value.

(Elastic Resistance Layer) As the elastic body used for the elastic resistance layer, for example, polybutadiene, natural rubber, polyisoprene, SBR (styrene butadiene rubber), CR (chloroprene rubber), EPDM (ethylene propylene.
Dienter rubber), IIR (butyl rubber), NBR (nitrile butadiene rubber), silicone rubber, urethane rubber, epichlorohydrin rubber, and other rubbers, polystyrene resin such as RB (butadiene resin), SBS (styrene-butadiene-styrene elastomer), and polyolefin Resin, polyester resin, polyurethane, PVC
(Polyvinyl chloride), an acrylic resin, a styrene / vinyl acetate copolymer, a butadiene / acrylonitrile copolymer, or other polymeric material to which elasticity is imparted can be used.

Of these, polyolefin materials are widely used. This is because polyolefin-based materials, particularly molded articles made of EPDM, have no functional groups on the surface, and therefore have good solvent resistance, ozone resistance, heat resistance, etc., and are excellent in molding processability and relatively inexpensive and contaminated. The reason is that the elastic body is an elastic body that can maintain stable performance even when it is used for a long period of time such as an electrophotographic apparatus due to its poor property.

The use form of the elastic resistance layer may be solid or foam, and the surface thereof may be a polished surface of the solid or foam, a surface to which the inner surface of the mold is transferred, or a skin surface, and is not particularly limited. Although it is not a matter of particular importance, a sufficient nip width with the photoconductor can be secured, uniform charging can be performed, and a muffling effect against the charging noise generated when the voltage applied to the charging member is a superposition of DC voltage and AC voltage It is preferable to have a surface to which the smooth inner surface of the mold is transferred, which is made of a foamed material having

When a foam is produced by using a foaming agent, the foaming agent may be A.I. D. C. A. (Azodicarbonamide) type, D.I. P. T. (Di-nitrosopentamethylenetetramine) system, O.I. B. S. H. (4,4'-
Oxybis-benzenesulfonyl-hydrazide) system,
T. S. H. (P-trienesulfonyl hydrazide)
System, A. I. B. N. (Azobisisobutyronitrile)
Systems can be used, in particular A. D. C. A series,
O. B. S. With the H-based blend system, a dense foam and a vulcanized tight (high crosslink density) foam can be obtained.

The material of the conductive elastic layer is EP
In addition to DM, synthetic rubber such as natural rubber, butadiene rubber, urethane rubber, or resin may be used. The form of use may be solid or sponge, but a sponge is preferable from the viewpoint of low hardness for proper nip width. Further, it may be a non-rotating roller, a blade-shaped pad member, or the like.

(Conductive Substrate) As the conductive substrate, one having strength as a substrate and exhibiting conductivity is suitable.
These materials include iron, stainless steel, aluminum,
There are conductive plastics and the like, and more specifically, SUM and the like are used.

(Manufacturing Method of Conductive Member) As a manufacturing method of the conductive member of the present invention, an elastic resistance layer is provided on the conductive substrate by extrusion molding using solid rubber, injection molding using liquid rubber, or the like. Further, a method of forming a coating layer by tube molding, dipping, spray coating or the like can be mentioned. More specifically, a conductive member can be manufactured by forming an elastic resistance layer by an extrusion molding method and forming a coating layer by dipping.

(Photosensitive Drum) The photosensitive member is provided on the photosensitive drum substrate. As the photosensitive drum base, one having conductivity on the support itself, for example, metal such as aluminum, aluminum alloy, stainless steel, nickel can be used. In addition, aluminum, aluminum alloy, indium oxide-tin oxide alloy, etc. can be vacuumized. It is possible to use a plastic having a layer formed by vapor deposition, a support in which conductive particles (for example, carbon black, tin oxide particles, etc.) are coated on a metal or plastic together with an appropriate binder, and a plastic having a conductive binder. .

An undercoat layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. The subbing layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, etc.), polyurethane, gelatin, aluminum oxide and the like. The thickness of the undercoat layer is 5 μm or less, preferably 0.5 μm to 3 μm. The undercoat layer has a function of 1 × 10 ⁷ Ω · cm in order to exert its function.
The above is desirable.

The photoconductor can be formed by coating an organic or inorganic photoconductor with a binder resin as required, or can be formed by vapor deposition. As the form of the photosensitive layer, a function-separated laminated photosensitive layer of a charge generation layer and a charge transport layer is preferable. The charge generation layer can be formed by vapor deposition of a charge generation substance such as an azo pigment, a phthalocyanine pigment, a quinone pigment, and a perylene pigment, or by coating with a suitable binder resin (without a binder). The thickness of the charge generation layer is 0.01 μm to 5 μm,
It is particularly preferably 0.05 μm to 2 μm. The charge transport layer can be formed by dissolving a charge transport substance such as a hydrazone compound, a styryl compound, an ocisazole compound, and a triarylamine compound in a binder resin having film-forming properties. The thickness of the charge transport layer is preferably 5 μm to 50 μm, particularly preferably 10 μm to 30 μm. A protective layer may be provided on the photosensitive layer to prevent deterioration due to ultraviolet rays or the like.

The photosensitive member is not limited to a drum shape, but may be a belt shape or a sheet shape, and the charging member may be a non-rotating roller or a blade-shaped pad member.

(Process Cartridge) As shown in FIG. 3, the nip portion 13 is charged by the power source 3 and the nip portion 1 is charged.
3 moves as the photoconductor 12 moves, so that the photoconductor 1
2 The entire surface is charged. Then, as shown in FIG.
A latent image is formed by exposing with a laser beam L according to image information, then developed with toner in a developing device 31, transferred to a transfer material by a transfer member 32 in a transfer portion, and thermally fixed by a fixing device 33. On the other hand, the photosensitive drum 10 is cleaned by the cleaner 34 after transfer to prepare for the next image formation.

As shown in FIG. 4, the charging member 2, the cleaner 34, the photosensitive drum 10, the developing device 31 and the like can be integrally detached as a process cartridge 35.

The process cartridge is a main body of an image forming apparatus in which an electrophotographic photosensitive member as an image carrier and at least one of charging means, developing means, cleaning means as operating means are integrally formed into a cartridge. It is supposed to be removable. More specifically, the process cartridge is a cartridge in which a charging unit, a developing unit or a cleaning unit, and an electrophotographic photosensitive member are integrally formed, and the cartridge is used as an image forming apparatus (for example,
It is detachable from the main body of a copying machine, LBP, etc.

Further, at least one of the charging means, the developing means and the cleaning means and the electrophotographic photosensitive member are integrally made into a cartridge to form an image forming apparatus (for example, a copying machine, an LP).
(B, etc.) It can be detachable from the main body. The process cartridge may include at least the photosensitive drum and the charging member.

[0055]

EXAMPLE A charging member was manufactured as a conductive member. Unless otherwise specified, "part" represents "part by mass", "%" represents "% by mass", and reagents and the like were commercially available high-purity products.

(Example 1) Charging member 1 The charging member used in this example was manufactured by the following method.

As an elastic material used for the elastic resistance layer, 100 parts of ethylene-propylene-diene terpolymer EPT4045 (trade name) manufactured by Mitsui Petrochemical Co., Ltd. as a raw material rubber,
Stearic acid 1 part as a processing aid, zinc oxide 5 parts as a vulcanization acceleration aid, Asahi Carbon SRF carbon black Asahi # 35 (trade name) 50 parts as a filler, Ketjen Black International Ket as a conductive agent Cheng Black EC600JD (trade name) 7 parts, Idemitsu Kosan paraffin oil PW-380 (trade name) as a plasticizer
50 parts, 0.5 part of sulfur as a crosslinking agent, 2 parts of 2-mercaptobenzothiazole (MBT) as a vulcanization accelerator, 1 part of tetramethylthiuram disulfide (TMTD), 1 part of zinc dibutyldithiocarbamate (ZnBDC), a foaming agent And 4 parts of azodicarbonamide (ADCA) as
4'-oxybisbenzenesulfonyl hydrazine (O
4 parts of BSH) were mixed with an open roll to obtain an unvulcanized rubber composition. Next, using an extruder in which a mandrel having an outer diameter of φ5.0 mm and a die having an inner diameter of φ7.5 mm were set, the obtained raw material composition was extruded into a tube shape, and then the length was set to a mold. The inner hole was cut to the same length as 224 mm, and the outer diameter was φ9.8 mm and the inner diameter was φ6.
A tubular raw material composition having a size of 3 mm was produced.

Next, as schematically shown in FIG. 2, a conductive substrate S coated beforehand with chlorinated olefin Super Clone 842 (trade name) manufactured by Nippon Paper Industries Co., Ltd. as an adhesive.
The core metal 5 as a UM was inserted into the tube-shaped raw material composition 22, and fixed inside the cylindrical mold 20 by the lids 21 provided at both ends of the mold. Then, it is inserted into a heating plate heated to 180 ° C. in advance and heated for 15 minutes for vulcanization and foaming.
1.8 mm, length 224 mm, average diameter of pores formed by foaming is 100 μm, and surface has 10-point average roughness Rz 0.9.
A conductive foam body that serves as a μm elastic resistance layer was obtained.

The obtained conductive foam was impregnated with an adhesive solution prepared by diluting chlorinated olefin Super Clone 813 (trade name) manufactured by Nippon Paper Industries Co., Ltd. in toluene by dipping for 30 seconds and then at 130 ° C. Dry in the oven for 2 minutes.

On the other hand, as liquid A, water-based polyurethane paint Elastron MF-9 (product name) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was added,
Kao's Dispersant DEMOL ST for the dry mass of paint
(Product name) 0.1%, Kao company defoamer No1 (Product name)
0.01%, volume specific resistance value 5 × as conductive material (A)
A solid solution of 10 ³ Ωcm of zinc oxide manufactured by Shiramizu Chemical Industry Co., Ltd. was mixed at 300% and dispersed with a paint shaker for 4 hours. The average particle size of the conductive material (A) in this solution was 180 nm when measured by a centrifugal type particle size distribution measuring method (CAPA700, Horiba, Ltd.).

Also, as the liquid B, the same as the liquid A except that the conductive material (B) was barium sulfate pastron 4350 (trade name) treated with tin oxide manufactured by Mitsui Mining & Smelting Co., Ltd. having a volume resistivity of 9 × 10 ⁴ Ωcm. To prepare a solution. The average particle diameter of the conductive material (B) in this B liquid was 140 nm.

Next, the liquid A and the liquid B were mixed in a ratio of urethane of 1: 1 to prepare a coating material for the coating layer, which was applied to the conductive foam treated with the adhesive by dipping and dried. To form a coating layer having a layer thickness of 20 μm.

The electric resistance value of the obtained charging member 1 is 3 × 1.
It was 0 ⁶ Ω.

Regarding the electric resistance value of the charging member, a DC voltage of 100 V was applied between the conductive substrate and the metal drum while the coating layer was in contact with the cylindrical metal drum and rotated, and It was determined by measuring the voltage applied to the resistor connected in series with.

Further, the charging member 1 is attached to the contact charging device, and the minimum AC voltage (sand voltage) at which abnormal images due to poor charging are eliminated and the minimum AC voltage (leak voltage) at which abnormal images are generated due to pinholes are set. It was measured.

FIG. 3 shows the structure of the contact charging device.
The second charging member is connected to the power source 3 and is in contact with the photosensitive drum 10, which is a drum-shaped electrophotographic photosensitive member. The photosensitive drum 10 has a photosensitive drum substrate 11 rotatable in the R direction,
In this embodiment, a photoconductor drum having a structure in which a photoconductor such as PC, amorphous silicon, selenium, or zinc oxide is covered is used. The shape of the photosensitive drum is not limited to the drum shape, and may be a belt shape or a sheet shape.

The charging member is brought into contact with the photoconductor to form an electric circuit connected to the photoconductor. In this state, a power supply 3 applies to the charging member a superposition of a DC voltage of -670 V while changing an AC voltage of 920 Hz,
The peripheral speed of the OPC photosensitive drum was set to 100 mm / sec, and the presence or absence of an abnormal image was confirmed. In addition, about 0.3 (mmφ) pinholes were artificially provided on the surface of the OPC photosensitive member in order to evaluate the occurrence of abnormal images due to pinholes.

The results obtained are shown in Table 1.

[0069]

[Table 1]

As is clear from Table 1, the sandy ground voltage of the charging member 1 was 2.0 kV and the leak voltage was 2.9 kV. Good images were confirmed in this voltage range of 0.9 kV, and there was no problem in use. I understood.

(Embodiment 2) Charging member 2 As the liquid A of the coating material for the coating layer, a solid solution of indium oxide manufactured by Shinko Kagaku Kogyo Co., Ltd. having a volume resistivity of 2 × 10 ⁻¹ Ωcm as the conductive material A was used as a dry mass of polyurethane. Mixed with 20% by weight, and used as the B liquid in the urethane paint in the case of the charging member 1 and as the conductive material B in the volume specific resistance value of 9 × 10 ⁴
Ωcm Mitsui Mining & Smelting Co. tin oxide treated barium sulfate
Pasteron 4350 (trade name) 300% is mixed and dispersed by a paint shaker to prepare a mixed liquid in which the average particle diameter of the conductive material A is 180 nm and the average particle diameter of the conductive material B is 140 nm, and then the liquid A and the liquid B are mixed. A charging member 2 was prepared in the same manner as the charging member 1 except that a coating layer-soluble coating material was prepared by mixing the liquid and urethane in a ratio of 1: 1.

As shown in Table 1, the electric resistance value of the charging member 2 was 1 × 10 ⁶ Ω. The sand voltage is 2.0 kV
And the leak voltage is 2.7 kV, which is 0.7 kV.
A good image was confirmed in the voltage range of V, and it was found that there was no problem in use.

(Embodiment 3) Charging member 3 As the coating solution coating liquid A, the urethane paint in the case of the charging member 1 was used, and as the conductive material A, the volume specific resistance value was 2 × 10 ^-1 Ω.
cm indium oxide solid solution (manufactured by Shinko Kagaku Kogyo Co., Ltd.) is 60% of the dry mass of polyurethane, and the conductive material B is used as the urethane paint in the case of the charging member 1 as the B liquid.
As a solid solution SN-100P (trade name) of tin oxide manufactured by Ishihara Sangyo Co., Ltd. having a volume resistivity value of 2 × 10 ¹ Ωcm,
Mix 0% and disperse each with a paint shaker to prepare a coating liquid in which the average particle diameter of the conductive material A is 180 nm and the average particle diameter of the conductive material B is 100 nm, and then the liquid A and the liquid B are used in a ratio of urethane. A one-to-one mixed coating layer-soluble coating material was prepared, and charging member 3 was prepared in the same manner as charging member 1.

As shown in Table 1, the electric resistance value of the charging member 3 was 5 × 10 ⁷ Ω. In addition, sand voltage is 2.4k
V, the leak voltage is 3.0 kV or more.
A good image was confirmed in the voltage range of V or higher, and it was found that there was no problem in use.

(Embodiment 4) Charging Member 4 As the coating liquid for coating layer A, the urethane paint in the case of charging member 1 was used, and as the conductive material A, the volume specific resistance value was 2 × 10 ⁻¹ Ω.
cm indium oxide solid solution (manufactured by Shinko Kagaku Kogyo Co., Ltd.) is 60% of the dry mass of polyurethane, and the conductive material B is used as the urethane paint in the case of the charging member 1 as the B liquid.
With volume resistivity 9 × 10 ⁴ Ωcm manufactured by Mitsui Mining & Smelting Co., Ltd. as tin oxide treated barium sulfate pastron 4350
(Brand name) and 20% are dispersed by a paint shaker, and the average particle diameter of the conductive material A is 70 nm, and the conductive material B is
A coating liquid having an average particle size of 100 nm is prepared, and then a coating layer-soluble coating material is prepared by mixing the liquid A and the liquid B in a ratio of 1: 1 with urethane, and the charging member 4 is prepared in the same manner as the charging member 1. Was produced.

As shown in Table 1, the electric resistance value of the charging member 4 was 7 × 10 ⁶ Ω. In addition, sandy ground voltage is 1.4kV
Hereinafter, the leak voltage was 3.0 kV or more, and a good image was confirmed at any measurement voltage.

(Embodiment 5) Charging Member 5 As the coating liquid for coating layer A, the urethane paint in the case of charging member 1 was used, and as the conductive material A, the volume specific resistance value was 2 × 10 ⁻¹ Ω.
cm indium oxide solid solution (manufactured by Shinko Kagaku Kogyo Co., Ltd.) is 60% of the dry mass of polyurethane, and the conductive material B is used as the urethane paint in the case of the charging member 1 as the B liquid.
As a solid solution of tin oxide having a volume resistivity value of 5 × 10 ³ Ωcm and 120%, respectively, are dispersed by a paint shaker to obtain a coating liquid in which the average particle diameter of the conductive material A is 40 nm and the average particle diameter of the conductive material B is 100 nm. Was produced. Then, a coating layer-soluble coating material was prepared by mixing the liquid A and the liquid B in a ratio of urethane of 1: 1 and the charging member 5 was prepared in the same manner as the charging member 1.

As shown in Table 1, the electric resistance value of the charging member 5 was 2 × 10 ⁶ Ω. In addition, sandy ground voltage is 1.4kV
Hereinafter, the leak voltage was 3.0 kV or more, and a good image was confirmed at any measurement voltage.

(Comparative Example 1) Charging member 6 As the coating material for the coating layer, the volume specific resistance value of the conductive particles was 5 as the dry mass of the water-based polyurethane coating material Elastron MF-9 (trade name) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. × 10 ³ Ωc
Disperse 150% of m zinc oxide (manufactured by Hakusui Chemical Co., Ltd.), 0.1% of Kao's dispersant DEMOL ST (trade name), and 0.01% of Kao's defoamer (No1) with a paint shaker. Then, a coating material having an average particle diameter of the conductive particles of 100 nm was prepared. Using this paint, a charging member 6 was prepared in the same manner as the charging member 1.

As shown in Table 1, the electric resistance value of the charging member 6 was 3 × 10 ⁷ Ω. The leak voltage is 3.0k
Although it was V or more, the sandy voltage was extremely high at 2.8 kV, and it was found that it can be used only in this voltage range of 0.2 kV.

[0081]

According to the present invention, in the conductive material contained in the coating layer of the conductive member, the volume resistivity is large with respect to the compounding amount (Ma) of the conductive material (A) having a small volume resistivity. By setting the mass ratio (Mb / Ma) of the compounding amount (Mb) of the conductive material (B) to 1/3 times or more and 15 times or less and further controlling the volume specific resistance value of the conductive material within a predetermined range, charging The applied voltage at which an abnormal image is generated due to unevenness or defective charging can be made higher than the applied voltage at which a diamond-shaped abnormal image is generated when a pinhole exists, and the area of the applied voltage required to obtain an appropriate image Can be secured widely.

As a result, the conductive member can be stably supplied even with respect to the compounding amount of the conductive material in the conductive member which can obtain a proper image. Further, the conductive member provided by the present invention eliminates the occurrence of an abnormal image even in an electrophotographic apparatus having a fast process speed or a low-cost electrophotographic apparatus, and the charging member can be stably and inexpensively provided for production. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view for explaining an example of a conductive member of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining an example of a mold used when manufacturing the conductive member of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining a process cartridge or a contact charging device.

FIG. 4 is a schematic cross-sectional view for explaining a process cartridge and an image forming apparatus.

[Explanation of symbols]

2 charging member 3 power supplies 5 Conductive substrate 6 resistor 7 Elastic resistance layer 8 coating layer 10 Photosensitive drum 11 Photosensitive drum substrate 12 photoconductor 13 Nip part 20 Cylindrical mold 21 Lid 22 Tube-shaped raw material composition 31 Developer 32 Transfer member 33 Fixer 34 cleaner 35 process cartridge L laser light

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/08 501 501 G03G 15/08 501D 5G307 15/16 103 15/16 103 // H01B 5/14 H01B 5 / 14 ZF term (reference) 2H071 BA43 DA06 DA08 DA09 2H077 AD06 FA12 FA13 FA16 FA22 FA23 FA26 2H200 FA16 FA18 GA17 GA23 HA03 HB12 HB22 HB45 HB46 JA02 JA25 JA26 MA01 MA03 MA04 MA06 MA17 MA20 MB01 MB04 3J103A21 A14 A14 A14 A14 A32 A14 A32 A14 FA18 GA57 GA58 HA04 HA20 4F100 AA07H AA17C AA17H AA25H AA28H AA37H AB01 AH02H AK01C AK10G AK51 AK75 AR00A AR00B BA03 BA10A BA10C CA03 CA21C CA23 CG07C01 J02J02JC01 J02J02G01G JH01G

Claims (7)

[Claims] 1. A conductive member having at least an elastic resistance layer and a coating layer laminated in this order on a conductive substrate, the coating layer containing two or more conductive materials having different volume resistivity values. And the volume resistivity (Ra) of the conductive material (A) having a small volume resistivity is 1 × 10 ⁻¹ Ωc
The volume resistivity (Rb) of the conductive material (B) having a volume resistivity of 5 × 10 ³ Ωcm or less and a large volume resistivity is 2 ×.
It is not less than 10 ¹ Ωcm and not more than 1 × 10 ⁵ Ωcm, and the mass ratio (Mb / Ma) of the blending amount (Mb) of the conductive material (B) to the blending amount (Ma) of the conductive material (A) is 1 / 3 or more and 15 or less, The electroconductive member characterized by the above-mentioned. 2. The conductive material (A) is blended in an amount of 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the resin contained in the coating layer, and the conductive material with respect to 100 parts by mass of the resin contained in the coating layer. The conductive member according to claim 1, wherein the compounding amount of the material (B) is 10 parts by mass or more and 150 parts by mass or less. 3. The average particle diameter (Da) of the conductive material (A).
Is 70 nm or less, and the average particle diameter (Db) of the conductive material (B) is 100 nm or less. 4. The ratio (Rb / Ra) of the volume specific resistance value (Rb) of the conductive material (B) to the volume specific resistance value (Ra) of the conductive material (A) is larger than 1 and 3 × 1.
The electroconductive member according to claim 1, wherein the electroconductive member is 0 ⁴ or less. 5. The conductive member according to claim 1, wherein at least one of the conductive material (A) and the conductive material (B) is a solid solution of a metal oxide. 6. A process cartridge in which the conductive member according to any one of claims 1 to 5 is arranged and which is detachably attached to an image forming apparatus main body. 7. An image forming apparatus in which the conductive member according to claim 1 is arranged as a charging member.