JPH08254876A - Contact-electrifying member, its production and electrophotographic device using it - Google Patents

Abstract

PURPOSE: To provide a contact-electrifying member which has good surface smoothness and is excellent in durability and environment resistance by providing the electrifying member with an elastic layer and a surface layer on a feed electrode layer and providing the surface layer with crosslinked polymer cross-linked by an electron beam. CONSTITUTION: The roller type electrifying member 2 comes into contact with the surface of a photoreceptor 1 and uniformly primarily electrifies the surface of the photoreceptor 1 to have specified polarity and potential. The member 2 is constituted of a core bar 2c, the elastic layer 2b formed on the outer periphery of the core bar 2c, and further the surface layer 2a formed on the outer periphery of the layer 2b. Both ends of the core bar 2c are rotatably born by bearing members and arranged in parallel with the drum type photoreceptor 1, so that the member 2 is pressure-welded to the surface of the photoreceptor 1 by specified pressing force by a pressing means and follows to be rotated as the photoreceptor 1 is driven to be rotated. The surface layer 2a has the crosslinked polymer cross-linked by the use of an electron beam. The surface layer 2a is formed by applying the electron beam to produce cross-linking reaction after coating the surface of the elastic layer 2b with the polymer which can be cross-linked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member in which a charging member to which a voltage is applied is brought into contact with the surface of a member to be charged, a method of manufacturing the charging member, and an electrophotographic apparatus using the charging member.

[0002]

2. Description of the Related Art For example, in an image forming apparatus such as an electrophotographic apparatus (copier, printer, etc.), an electrostatic recording apparatus, etc., an electrophotographic photosensitive member as a member to be charged or an image carrier such as an electrostatic recording dielectric is charged. A corona discharger, which is a non-contact charging type, has been mainly used as a treatment means.

The corona discharger has advantages such as excellent uniform charging property, but requires an expensive high voltage power source. It requires space such as itself and shielded space for high voltage power supply. There is a problem that corona products such as ozone are relatively often generated, and additional means and mechanisms are required to deal with them, which are factors that increase the size and cost of the device. ing.

Therefore, recently, instead of the corona discharger,
The adoption of contact charging type charging means is being promoted. In the contact charging, a charging member to which a voltage is applied is brought into contact with a member to be charged to charge the surface of the member to be charged to a predetermined polarity and potential, and the power supply can be lowered in voltage. There are advantages such as less generation of corona products such as ozone, simple structure and cost reduction.

The contact charging device is divided into a charging member to be brought into contact with an object to be charged from the shape and form of the charging member. The charging member is a roller type charger (charging roller) (Japanese Patent Laid-Open No. 63-7).
No. 380, No. 56-91253, etc.), a blade type charging device using a blade-shaped member (charging blade) (Japanese Patent Laid-Open No. 64-24264, No. 56-194349, etc.), and a brush-shaped member (charging brush). And a brush type charger (Japanese Patent Laid-Open No. 64-24264, etc.).

The voltage applied to the charging member may be a system in which only a DC voltage is applied (DC application system), but the peak is more than twice the charging start voltage of the member to be charged when the DC voltage is applied to the contact charging member. Voltage (PEAK TO PEAK)
A method of forming an oscillating electric field (alternating electric field, AC electric field: that is, an electric field or voltage whose voltage value periodically changes with time) having a gap between a contact charging member and a member to be charged to charge the surface of the member to be charged. The (AC application method) is effective because it allows uniform charging.

The charging roller of the roller type charger is rotatably supported by a bearing, is pressed against the surface of the body to be charged with a predetermined pressure, and is rotated by the movement of the surface of the body to be charged.

The charging roller is usually a multilayer structure comprising a cored bar provided in the center, a conductive elastic layer provided in a roller shape around the cored bar, and a surface layer provided on the outer periphery thereof. . Among the above layers, the core metal is a rigid body for maintaining the shape of the roller and also has a role as a power feeding electrode layer.

The elastic layer usually has a volume resistivity of 10 ⁴
Since it is a conductor of -10 ⁹ Ω · cm and also has a role of ensuring uniform contact with the surface of the body to be charged by elastically deforming, it is usually flexible with a rubber hardness (JIS A) of 70 degrees or less. A vulcanized rubber having is used.

The surface layer improves the charging uniformity of the member to be charged, prevents the occurrence of leaks due to pinholes on the surface of the member to be charged, prevents the adhesion of toner particles and paper powder, and further improves elasticity. It also has a role of preventing bleeding of softening agents such as oils and plasticizers used to reduce the hardness of the layer. The surface layer has a volume resistivity of 10 ⁵ to 1
It was 0 ¹³ Ω · cm, and was conventionally formed by applying a conductive paint.

Further, the charging member is
It has excellent mechanical strength, wear resistance, ozone resistance, heat and cold resistance, low hygroscopicity, rich flexibility, creep resistance, low compression set and easy workability.
It is necessary for the surface layer material to be formed of a material that satisfies all the conditions that it should naturally have.

If a material that does not meet the above-mentioned conditions is used, the charging roller deteriorates during use or cannot adapt to changes in the use environment, resulting in image defects.

Further, as described above, when an oscillating electric field is formed between the charging device and the body to be charged in order to make the body to be charged uniformly, mechanical vibrations of both are induced, resulting in abnormal noise. Occurs. This is called charging noise, and its suppression is an important subject for study.

A method of reducing the rubber hardness of the elastic layer is effective for reducing the charging noise, but it is difficult to sufficiently lower the hardness only by increasing the amount of the softening agent. The use of rubber) is being considered. This will be referred to as a foam type charging roller, and one that does not use a foam will be referred to as a solid type charging roller.

In the case of the foaming type charging roller, since the skin layer formed during vulcanization has poor surface smoothness, it is necessary to remove the skin layer by polishing, but it is difficult to make the bubble diameter uniform. When large bubbles are exposed on the surface due to polishing, dents are generated in the surface layer applied in the next step. If a charging roller having a dent in the surface layer is used, poor charging occurs and a good image cannot be obtained.

On the other hand, a method has been proposed in which a conductive polymer material is formed into a film in the shape of a seamless tube in advance, and the surface layer is formed by coating the elastic layer with the film (Japanese Patent Laid-Open Publication No. 3-301). 59682 and 5-2313).

When the above seamless tube is used, the above-mentioned dent of the surface layer due to large bubbles on the surface of the elastic layer is not generated, and a charging roller having excellent smoothness can be obtained. However, the surface layer plays various roles as described above, and needs to have excellent mechanical strength, abrasion resistance, ozone resistance, heat resistance, cold resistance, etc. as described above.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide a contact charging member excellent in such physical properties.

Another object of the present invention is to provide a method of manufacturing such a contact charging member.

Still another object of the present invention is to provide an electrophotographic apparatus using such a contact charging member.

[0021]

The contact charging member according to the present invention comprises:
In a contact charging member that contacts a surface of a charged body and applies a voltage to charge the charged body, the charging member has an elastic layer and a surface layer on a power supply electrode layer, and the surface layer is an electron layer. It is characterized by having a crosslinked polymer crosslinked by a wire.

Further, according to the present invention, the surface to be charged is brought into contact with
In addition, in the method of manufacturing a contact charging member for applying a voltage to charge an object to be charged, (1) a step of forming an elastic layer on a power supply electrode layer, and (2) forming a polymer in the form of a seamless tube. And (3) electron beam cross-linking the polymer forming the seamless tube, and (4) covering the elastic layer with the cross-linked seamless tube. It is a manufacturing method of a contact charging member.

The contact charging member according to the present invention has good surface smoothness and excellent durability and environmental resistance.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The elastic layer used in the present invention is composed of a conductive rubber composition and contains an elastic body and a conductivity-imparting agent as main components.

As the elastic body, silicone rubber, ethylene-propylene rubber, fluorine rubber, urethane rubber, epichlorohydrin rubber, epichlorohydrin-ethylene oxide rubber, acrylic rubber, ethylene-acrylic rubber, natural rubber, isoprene rubber, butadiene rubber, 1,2- Polybutadiene, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, modified nitrile rubber, butyl rubber, chlorosulfonated polyethylene, polysulfide rubber, chlorinated polyethylene, and other rubbers, and styrene-based, olefin-based, ester-based, urethane-based, isoprene System, 1, 2
-Butadiene-based, vinyl chloride-based, amide-based, and ionomer-based various thermoplastic elastomers can be appropriately used.

Known materials can be used as the conductivity-imparting agent for making the elastic layer conductive, and examples thereof include carbon particles such as carbon black and graphite, metal particles such as nickel, silver, aluminum and copper, and tin oxide. Conductive metal oxide fine particles mainly composed of zinc oxide, titanium oxide, aluminum oxide, silica, etc., doped with impurity ions having different valences, conductive fibers such as carbon fibers, metal fibers such as stainless fibers, carbon Whisker,
Examples thereof include conductive whiskers such as conductive potassium titanate whiskers in which the surface of potassium titanate whiskers is made conductive with metal oxide or carbon, and conductive polymer fine particles such as polyaniline and polypyrrole.

The elastic layer containing the conductivity-imparting agent is usually formed adjacent to the periphery of the core metal as the power feeding electrode layer and has the shape of a roller. Hereinafter, the core metal and the elastic layer are collectively referred to as a roller body.

The method for forming the elastic layer is not particularly limited, and injection molding methods, extrusion molding methods, compression molding methods, and other molding methods that are commonly used for rubber molding can be applied.
As a method of integrating the cored bar and the elastic layer, the elastic layer can be directly formed around the cored bar by the insert molding method, or a thick tube-shaped elastic layer can be formed and the cored bar can be formed. It can also be fitted on.

In order to reduce the hardness of the elastic layer, the conductive rubber composition may contain a softening agent such as oil or a plasticizer. Further, a rubber foam can be used as another means for reducing the hardness.

In the present invention, it is important that the surface of the elastic layer is macroscopically smooth, and when sufficient smoothness cannot be obtained by molding, for example, when a rubber foam is used, or a compression molding method is used. When burrs occur due to the adoption of the above, smoothing processing by secondary processing such as polishing is required.

Further, since the elastic layer is usually used by being pressed against a member to be charged, it is desirable that the elastic layer has a small compression set. Therefore, it is desirable to use a vulcanized rubber or a rubber cross-linked body.

The thickness of the elastic layer is usually 2 to 5 mm,
The volume resistance value is 10 ² to 10 ⁹ Ω · cm, preferably 10 ⁴ to 10 ⁸ Ω · cm.

As the polymer used for forming the surface layer of the contact charging member of the present invention, various rubbers and various thermoplastic elastomers used for the elastic body are suitable, and various plastics such as, for example, Polyolefins such as polyethylene, various ethylene-based copolymers, polypropylene, propylene / ethylene copolymers, polybutene, poly-4-methylpentene-1; nylon 6, nylon 66, nylon 11, nylon 12, other copolymerized nylon, etc. Polyamide: Saturated polyester such as PET, PBT (polybutylene terephthalate); Polycarbonate: Polystyrene, HIPS (high impact polystyrene), ABS, AES (acrylonitrile EPDM styrene), AAS (acrylonitrile acrylate styrene) What styrene resin, acrylic resin, vinyl chloride resin: vinylidene chloride resin; polyacetal; polyphenylene oxide or a polystyrene modified products; polyimide resin; polyarylate; vinylidene fluoride homopolymer and copolymers, etc. can be used. Furthermore, a polymer alloy or polymer blend composed of two or more polymers selected from the above rubber, thermoplastic elastomer and plastic can also be used.

The surface layer can be formed by applying such a crosslinkable polymer on the surface of the elastic layer and then irradiating it with an electron beam to cause a crosslinking reaction.

When forming a seamless tube on the elastic layer on the surface layer, a conductive polymer composition comprising a polymer, the above-mentioned conductivity-imparting agent and, if necessary, other additives is first prepared. A film is formed into a tube by an extrusion molding method, an injection molding method, a blow molding method, or the like. Of the various molding methods described above, the extrusion molding method is particularly suitable.

The polymer cannot sufficiently satisfy the role of the surface layer and the conditions naturally required for the surface layer material by simply molding the polymer by the above-mentioned various molding methods. Therefore,
Electron beam crosslinking is performed to obtain a crosslinked polymer. As a method of cross-linking, there is chemical cross-linking in which a cross-linking agent such as sulfur, organic peroxide, amines or the like is added in advance depending on the type of polymer and a cross-linking reaction is caused under heating. Alternatively, the decomposition product of the cross-linking agent may migrate to the charged body and deteriorate the charged body.Therefore, pay attention to the cleaning treatment of the charged body, or the cross-linking agent may adhere to the charged body. Even so, it is necessary to design a material that does not easily deteriorate. On the other hand, the electron beam cross-linking method is superior to the chemical cross-linking method in that there is no risk of contamination of the charged body due to migration of the cross-linking agent or its decomposition product, and that high-temperature treatment is not required, In terms of safety, it is superior to the γ-ray crosslinking method.

The crosslinked polymer obtained by the above crosslinking method is
It is expected that the material has improved abrasion resistance, heat resistance, creep resistance, etc. as compared with the non-crosslinked polymer, and can satisfy all the conditions that the material for the surface layer should naturally have.

A typical structure of an electron beam irradiation apparatus used in the electron beam crosslinking method is shown in FIG. Electric power is supplied from the DC power source 20 to the acceleration tube 22 through the cable 21. The thermoelectrons emitted from the high temperature metal filament are accelerated in the acceleration tube 22 under an acceleration voltage of 150 to 1000 kV,
It becomes a spot-shaped electron beam. In the scanner 23, the electron beam is scanned by applying a high frequency magnetic field, and emitted from a window 24 formed of a metal foil such as titanium foil. The tube or coating to be cross-linked is placed directly under this window and is irradiated with an electron beam.

The timing of electron beam irradiation in the tube manufacturing process can be selected variously. In particular,
After the film formation, it may be before the external fitting process or after the external fitting. Further, when a film is formed by a coating method to form a surface layer, irradiation after drying the film is usually preferable.

In the electron beam irradiation method, the physical properties of the cross-linking agent are improved by mixing the cross-linking aid with the polymer in advance, depending on the type of the target polymer.

As the cross-linking aid, usually triallyl isocyanurate, tetraethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, trimethylol propane methacrylate, trimethylol propane triacrylate, triallyl cyanurate, tetramethylol methane tetramethacrylate, triaryl methacrylate. Polyfunctional monomers such as methoxyethoxyvinylsilane are used.

The irradiation dose is usually 5 to 50 Mrad.
(1 Mrad is equivalent to giving about 2.4 calories per gram of substance) is preferred, the type of polymer,
An appropriate level is selected depending on the presence or absence of the crosslinking aid, the acceleration voltage and the like.

The seamless tube has a thickness of 100 to 50.
It is 0 μm, preferably 150 to 350 μm.

Further, when a film is formed by the coating method to form a surface layer, the thickness is preferably 10 to 150 μm.

The resistance value of the surface layer is 10 ⁵ to 10 ¹³ Ω · cm, particularly 10 when the surface layer of the charging member is finished.
⁶ to 10 ¹² Ω · cm is preferable.

When the surface layer is formed by a seamless tube, the extrusion method is suitable as described above. That is,
A polymer and a conductivity-imparting agent and, if necessary, a compound in which a stabilizer and other additives are mixed are produced, and the compound is extruded from a die having a ring-shaped slit by an extruder, and cooled to continuously. Seamless tube can be manufactured.

A heat-shrinkable tube can be obtained by expanding the tube diameter during cooling or by reheating after cooling and using air pressurizing means, or a non-heat-shrinkable tube without expansion treatment.

The seamless tube used in the present invention may be either non-heat-shrinkable or heat-shrinkable, but the method of external fitting on the elastic layer differs depending on which one.

In the case of a non-heat-shrinkable tube, the inner diameter of the tube must be equal to or smaller than the outer diameter of the elastic layer in order to secure the adhesion between the elastic layer and the surface layer, and the tube diameter can be reduced by blowing compressed air. The outer fitting process is completed by inserting the roller body in the expanded state and releasing the air pressure.

On the other hand, in the case of a heat-shrinkable tube, it is desirable that the inner diameter of the tube is larger than the outer diameter of the elastic layer. After inserting the roller body, the elastic layer is heated in a constant temperature bath near the softening point for a predetermined time. External fitting is performed by heat-shrinking the tube so as to be in close contact with.

Next, each polymer will be described in more detail.

Polyethylene is usually a homopolymer of ethylene and is classified into low density polyethylene and high density polyethylene depending on the difference in crystallinity. In addition, as special grades, copolymers with vinyl acetate, acrylic monomers such as methylmethacrylate and acrylic acid, and various polar monomers such as maleic anhydride, vinyl chloride and vinylsilane are used. Further, in recent years, copolymers with α-olefins such as 1-butene (linear low-density polyethylene) have also been used. In the present invention, the above various homopolymers and copolymers are included in polyethylene.

Polyethylene has many excellent properties, but it has poor heat resistance, and when it is used as a polymer for the surface layer of a charging roller in an uncrosslinked state, it is deformed due to creep and the like, resulting in poor surface smoothness. Lost.

In addition to the above-mentioned conductivity-imparting agent, stabilizers, lubricants, various insulative fillers and the like can be added to the crosslinked polyethylene, if necessary.

Nylon 12 and nylon 11 are each a kind of polyamide, and nylon 12 is usually produced by polycondensation of ω-laurolactam or 12-aminododecanoic acid, and nylon 11 is produced by polycondensation of 11-aminoundecanoic acid.

The above-mentioned two types of polyamides have significantly different molecular structures as compared with general-purpose polyamides such as nylon 6 or nylon 66, are excellent in flexibility, abrasion resistance, low temperature characteristics, etc., and have low hygroscopicity. It has suitable properties as the surface layer of the roller. In addition to the conductivity-imparting agent, stabilizers and various insulating fillers may be added to the nylon 12 and the nylon 11 as needed.

When electron beam irradiation is carried out, an allyl compound such as triallyl isocyanurate can be mixed in advance to effect effective crosslinking by electron beam irradiation in air.

Ethylene-acrylic rubber is a relatively new rubber that was first marketed in the world by DuPont in 1975, and can be regarded as a kind of acrylic rubber in a broad sense, but in terms of molecular structure, it is a normal acrylic rubber. Is a big difference. As a result, it has a remarkable physical property.

The main component of the above-mentioned ethylene-acrylic rubber is a binary copolymer of ethylene and methyl acrylate. Usually, a carboxyl compound is used as a third monomer in order to impart cross-linking reactivity with certain amines. It is commercially available as a linked terpolymer. The ethylene-acrylic rubber may be any of the above binary copolymer and ternary copolymer.

The ethylene-acrylic rubber (1) has good heat resistance and good balance with oil resistance. (2) It has better low temperature properties than acrylic rubber. (3) It has features such as good weather resistance and ozone resistance, but is also excellent in that it has high mechanical strength, small compression set, and good bending resistance.

Carbon black, fumed colloidal anhydrous silica, calcium carbonate, barium sulfate, titanium dioxide and the like are usually used as the above-mentioned ethylene-acrylic rubber filler, but other inorganic and organic fillers may be added. Is.

As the antiaging agent, diphenylamine type and phenol type antioxidants are usually used.

Chlorinated polyethylene is a thermoplastic polymer produced by chlorinating polyethylene as a raw material. Chlorinated polyethylene is ozone resistant,
Rich in flexibility and heat resistance.

In addition to the above conductivity-imparting agent, stabilizers and various insulating fillers can be added to the chlorinated polyethylene. As the stabilizer, organic tin compounds, epoxy compounds, lead compounds, metal soaps, metal oxides and the like which are usually used are suitable.

The epichlorohydrin-ethylene oxide rubber is obtained by copolymerizing epichlorohydrin and ethylene oxide in almost equimolar amounts and is a special synthetic rubber having heat resistance, cold resistance and ozone resistance. The epichlorohydrin-ethylene oxide rubber of the present invention also includes a terpolymer in which a small amount of allyl glycidyl ether or the like is further added as a crosslinking monomer.

The above copolymers and terpolymers are remarkably improved in poor low-temperature properties, which is a drawback of epichlorohydrin homopolymers.

In addition to the above-mentioned conductivity-imparting agent, a vulcanizing agent, an antioxidant, various insulating fillers, processing aids and the like can be added to the epichlorohydrin-ethylene oxide rubber as required.

Chlorosulfonated polyethylene is 1951
Synthetic rubber developed by DuPont in
Obtained by the reaction of polyethylene with chlorine and sulfur dioxide. The molecular structure of chlorosulfonated polyethylene can be represented as follows. Chlorosulfonated polyethylene has ozone resistance, heat resistance,
It has excellent mechanical strength, wear resistance, bending resistance, etc. and has a small compression set.

The modified nitrile rubber has improved ozone resistance, which is a drawback of the above nitrile rubber, and is a blend of nitrile rubber and polyvinyl chloride (NBR / PV).
C), a blend of nitrile rubber and EPDM (NBR /
EPDM), hydrogenated nitrile rubber, carboxylated nitrile rubber and the like can be mentioned, and any of them can be easily obtained as a commercial product.

Of the various modified nitrile rubbers mentioned above, NBR
In / PVC, polar groups of NBR and PVC are chemically similar to each other, so that they are compatible with each other at almost any ratio, and as a result, a blended rubber having useful properties can be obtained. In particular, ozone resistance is remarkably improved as compared with NBR, and bending resistance and abrasion resistance are also improved. Further NBR / PVC
The extrusion processability of is also better than that of NBR alone, and a molded product with a smooth surface and beautiful gloss can be obtained.

NBR / EPDM is a relatively new blend rubber developed in the 1970's, and is one in which the excellent ozone resistance of EPDM is utilized to improve the ozone resistance of NBR. The property is also good.

The hydrogenated nitrile rubber is a rubber whose unsaturation degree is reduced by hydrogenating most of the large number of double bonds contained in the main chain of the above-mentioned nitrile rubber by a special method. Ozone resistance, heat resistance, cold resistance, mechanical strength, wear resistance, and workability are improved.

The shape of the charging member of the present invention may be any shape such as a roller or a blade, and can be selected according to the specification form of the electrophotographic apparatus.

FIG. 1 shows an example of an electrophotographic apparatus suitable for adopting the contact charging member of the present invention.

In the figure, reference numeral 1 is a photosensitive member as a member to be charged, and this example is a drum type having a conductive support 1b such as aluminum and a photosensitive layer 1a formed on the outer peripheral surface thereof as a basic constituent layer. Is an electrophotographic photoreceptor. It is rotationally driven around the support shaft 1d in the clockwise direction in the drawing at a predetermined peripheral speed.

Reference numeral 2 denotes a roller type charging member which is in contact with the surface of the photoconductor 1 and uniformly performs a primary charging process on the photoconductor surface to a predetermined polarity and potential. The charging member 2 is composed of a cored bar 2c, an elastic layer 2b formed on the outer periphery thereof, and a surface layer 2a formed on the outer periphery thereof, and both ends of the cored bar 2c are rotatably supported by bearing members (not shown). The drum-shaped photoconductor 1 is arranged in parallel and pressed against the surface of the photoconductor 1 with a predetermined pressing force by a pressing means (not shown) such as a spring, and is driven to rotate as the photoconductor 1 is rotationally driven.

Then, a predetermined direct current (D
C) By applying a bias or a direct current + alternating current (DC + AC) bias, the peripheral surface of the rotating photoconductor 1 has a predetermined polarity,
It is electrically charged to the electric potential.

The surface of the photosensitive member 1 that has been uniformly charged by the charging member 2 is then subjected to exposure of the target image information (laser beam scanning exposure, slit exposure of the original image, etc.) by the exposure means 10, and the peripheral surface thereof. An electrostatic latent image corresponding to the target image information is formed on. The latent image is then sequentially visualized as a toner image by the developing means 11.

This toner image is then transferred to the transfer means 12
Is sequentially transferred to the surface of the transfer material 14 that is conveyed from the sheet feeding means (not shown) to the transfer portion between the photosensitive body 1 and the transfer means 12 at an appropriate timing in synchronism with the rotation of the photosensitive body 1. To go. The transfer unit 12 of this example is a transfer roller, and the toner image on the surface of the photosensitive member 1 is transferred to the surface of the transfer material 14 by charging the transfer material 14 from the back with a polarity opposite to that of the toner.

The transfer material 14 to which the toner image has been transferred is separated from the surface of the photosensitive member 1 and is forwarded to an image fixing means (not shown) to be subjected to image fixing and output as an image-formed product.

After the image is transferred, the surface of the photosensitive member 1 is cleaned by the cleaning means 13 to remove adhering contaminants such as untransferred toner, and is cleaned to be repeatedly used for image formation.

In the present invention, as shown in FIG. 1, a plurality of elements of the electrophotographic apparatus such as a photoconductor, a charging member, a developing means and a cleaning means can be integrally incorporated in a process cartridge. By doing so, the process cartridge can be attached to and detached from the apparatus main body. For example, the elastic member of the present invention used as a charging member, and optionally at least one of a developing unit and a cleaning unit are integrally incorporated in a process cartridge together with a photoconductor, and a guide unit such as a rail of the apparatus main body is used. It can be configured to be removable.

The charging member of the present invention can be used not only for transfer, for primary charging, for discharging electricity, but also for carrying a feeding roller and the like.

As the electrophotographic apparatus which can use the charging member of the present invention, there are a copying machine, a laser beam printer, an LED.
Examples thereof include a printer or an electrophotographic application device such as an electrophotographic plate making system.

[0085]

【Example】

(Example 1) First, a method for manufacturing a roller body having an elastic layer will be described. EPDM (Mitsui Petrochemical Co., Ltd., trade name:
EPT4045) 100 parts by weight (hereinafter referred to as "part") is used as an elastic body, and zinc flower No. 1-10 is used as a vulcanization accelerator and a reinforcing agent.
Parts, stearic acid 2 parts, vulcanization accelerator M (2-mercaptobenzothiazole) 2 parts, vulcanization accelerator BZ (zinc dibutyldithiocarbamate) 1 part, sulfur 2 parts, blowing agent azodicarbonamide (Sankyo Kasei) Product name: Celmic C) 5 parts, urea compound as a foaming aid (manufactured by Sankyo Kasei Co.,
Product name: Celton NP) 5 parts, FEF carbon 20 parts,
70 parts of insulating oil (paraffin oil) and 8 parts of conductive carbon black (trade name: Ketjen Black EC, manufactured by Lion Corporation) were mixed and uniformly kneaded using a two-roll to obtain a rubber compound. The rubber compound is wound around an iron cored bar coated with a primer, placed in a mold, preformed at 40 ° C and 100 kg / cm ² , and vulcanized by steam heating (160 ° C, 30 minutes) to form a skin layer. A foam type roller body having

Then, the skin layer was removed by polishing with a grinder to complete the roller body. The roller body has a core metal diameter of 6 mm, an outer diameter of 12 mm, and a core metal length of 250.
mm, and the elastic layer length was 230 mm.

The resistance was measured by the following method. That is, the roller body is placed on an aluminum plate and 500 g is applied to both ends.
A total load of 1 kg was applied to each and the resistance between the core metal and the aluminum plate was measured. The resistance of the above roller body is 2 × 10 ⁶ Ω
Met.

Next, on the roller body obtained by the above method, a non-heat-shrinkable tube, which is formed by using conductive polyethylene and cross-linked by electron beam irradiation, is externally fitted to the surface layer 2a.
Was formed. More specifically, high-pressure polyethylene (trade name: Suntec LD L681, manufactured by Asahi Kasei Corp.)
0) 100 parts, 10 parts of conductivity imparting agent (carbon black, manufactured by Tokai Carbon Co., Ltd., trade name: # 4500), and 2 parts of zinc stearate are melted, kneaded by an extruder, and granulated to form conductive polyethylene. I got a compound.

200 g of the above compound was extruded.
By extruding from a die having a ring-shaped slit heated to ℃ and cooling, a seamless tube-shaped molded product was continuously obtained.

Next, an electron beam irradiation device with an acceleration voltage of 250 kV (manufactured by Nisshin High Voltage Co., Ltd., trade name: Curetron)
Was used to irradiate the tube with an electron beam of 20 Mrad to generate cross-links.

The conductive crosslinked non-heat-shrinkable polyethylene tube thus obtained had an inner diameter of 11.5 mm and a wall thickness of 250 μ.
m and volume resistivity were 1 × 10 ⁶ to 1 × 10 ⁸ Ω · cm.

By inserting the roller body while blowing compressed air into the non-heat-shrinkable tube, the surface layer 2a in close contact with the elastic layer was formed to complete the charging roller. Table 1 shows the durability test results of the charging roller.

[0093]

<Test Method> The charging roller manufactured in Example 1 was mounted on a cartridge (EP-L, manufactured by Canon Inc.), and the cartridge was mounted on a laser beam printer (Laser Shot A404, manufactured by Canon Inc.) and visually observed. The quality of the output image was evaluated.

(◯: Sandy fog, black spots,
No defects such as pinholes occur. (Δ: Any of the above defects occurs in 50% of the output image.) (×: Any of the above defects occurs in the total number of output images.) H / H environment: 32.5 ° C. 85% RH N / N environment: 25.0 ° C, 50% RH L / L environment: 15.0 ° C, 10% RH

Example 2 Instead of polyethylene, 100 parts of nylon 12 (manufactured by Daicel Hüls, trade name: Daiamide L1700) was used, and 2 parts of triallyl isocyanurate was further added as a cross-linking aid to prepare carbon black. A conductive nylon 12 compound was obtained in the same manner as in Example 1 except that the amount was 8 parts. Next, a seamless tube was formed into a film by the same method as in Example 1 (however, the die temperature was 250 ° C.), and the acceleration voltage was 250 kV and 10
The electron beam of Mrad was irradiated.

The electrically conductive crosslinked non-heat-shrinkable nylon 12 tube obtained by the above method was externally fitted to the roller body obtained in Example 1 to complete the charging roller. The results of the durability test are shown in Table 2.

[0098] (The test method is the same as in Table 1. The same applies to the following tables.)

Example 3 Instead of the conductive polyethylene compound of Example 1, a conductive ethylene-acrylic rubber compound was prepared by the following method.

100 parts of ethylene-acrylic rubber (manufactured by Showa Denko / Dupont, trade name: Baymac D), 1 part of diphenylamine antioxidant (Nowguard 445), 2 parts of stearic acid, 0.5 parts of alkyl phosphate, octadecyl 0.5 parts of amine, 20 parts of FEF carbon, 2 parts of conductivity-imparting agent (Ketchen black EC), and 2 parts of triallyl isocyanurate are blended, and uniformly dispersed and kneaded using a two-roll to form a sheet. Got a rubber compound.

The above rubber compound was mixed with an extruder to
The film was extruded from a die having a ring-shaped slit heated to 5 ° C. and cooled to form a film in a seamless tube shape.

Acceleration voltage of 250 kV, 10
Cross-linking was generated by irradiation with Mrad electron beam.

The conductive crosslinked non-heat-shrinkable ethylene-acrylic rubber tube thus obtained had an inner diameter of 11.5 mm, a wall thickness of 300 μm, and a volume resistivity of 1 × 10 ⁶ to 1 × 10 ⁸ Ω.
・ It was cm.

By inserting the roller body obtained in Example 1 while blowing compressed air into the non-heat-shrinkable tube, the surface layer 2a adhered to the elastic layer was formed, and the charging roller was completed. Table 3 shows the results of the durability test.

[0105]

(Example 4) 70 parts of polypropylene (manufactured by Mitsubishi Petrochemical Co., Ltd., trade name: MA7) and EPDM (manufactured by Mitsui Petrochemical Co., Ltd., trade name: EPT404) were used instead of polyethylene.
5) A conductive polypropylene / EPDM compound was obtained in the same manner as in Example 1 except that a polymer blend of 30 parts was used and 2 parts of triallyl isocyanurate was further added as a crosslinking aid. Next, a seamless tube was formed into a film by the same method as in Example 1 (however, the die temperature was 220 ° C.), and the acceleration voltage was 250 kV and 10 Mrad.
Was irradiated with an electron beam. On the roller body obtained in Example 1, conductive crosslinked non-heat-shrinkable polypropylene /
The EPDM tube was externally fitted to complete the charging roller.
Table 4 shows the results of the durability test.

[0107]

Comparative Example 1 A charging roller was prepared in the same manner as in Example 1 except that the electron beam was not applied.
Table 5 shows the results of the durability test.

[0109]

Comparative Example 2 A charging roller was prepared in the same manner as in Example 2 except that the electron beam was not applied.
Table 6 shows the results of the durability test.

[0111]

Comparative Example 3 A charging roller was prepared in the same manner as in Example 3 except that the electron beam was not applied.
The durability test results are shown in Table 7.

[0113]

Comparative Example 4 A charging roller was prepared in the same manner as in Example 4, except that the electron beam was not applied.
Table 8 shows the results of the durability test.

[0115]

<Evaluation of Examples 1 to 4 and Comparative Examples 1 to 4>
The role of the surface layer in the charging roller and the conditions that should be naturally provided as the material for the surface layer are as described above.
It was described that when a material which does not satisfy these requirements is used, an image defect is caused by a durability test or an environmental test.

The charging rollers obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated from the above standpoints and shown in Table 1.
Results of ~ 8 were obtained.

From Tables 1 to 8, it can be seen that the charging roller having the surface layer formed by the seamless tube made of the crosslinked polymer of the present invention has excellent durability and environment resistance and is sufficiently practical. I understand.

Furthermore, the charging noise was also measured,
All were 55 dB or less, and it was found that there was no problem in practical use.

(Embodiment 5) An electron beam cross-linking heat-shrinkable tube (manufactured by Sumitomo Electric Industries, Ltd., trade name) is formed on the roller body obtained in Embodiment 1 by using conductive chlorinated polyethylene. : Sumitube G3) is fitted on the surface layer 2a
Was formed.

More specifically, the heat-shrinkable tube was externally fitted after being crosslinked by electron beam irradiation, and the tube inner diameter before shrinkage was 16.5 mm and the wall thickness was 250 μm.

The roller body was inserted into the heat-shrinkable tube and contracted by heating for 15 minutes in a thermostatic chamber at 200 ° C. in an air atmosphere to bring the surface layer 2a into close contact with the elastic layer.
Then, the charging roller was completed.

The volume resistivity of the tube after heat shrinkage is 1 × 1.
0 was ^{6 ~1 × 10 8 Ω · cm} . The results of the durability test are shown in Table 9.

[0124]

From Table 9, it can be seen that the charging roller having the surface layer formed by the seamless tube made of the cross-linked polymer of the present invention has excellent durability and environment resistance and is sufficiently practical. .

Furthermore, the charging noise was also measured,
All were 55 dB or less, and it was found that there was no practical problem.

Example 6 An outer surface of the roller body obtained in Example 1 is coated with a conductive paint containing alcohol-soluble nylon as a vehicle to form a film, which is irradiated with an electron beam. The surface layer 2a was formed by crosslinking soluble nylon.

More specifically, alcohol-soluble nylon (manufactured by Toray Industries, Inc., trade name: CM8000) 100
Part was dissolved in methanol / water mixed solvent, and the solid content concentration was adjusted to 2
It was set to 0% by weight. Next, a conductivity-imparting agent (produced by Tokai Carbon Co., Ltd., trade name: carbon black # 4500) in the above solvent.
3 parts and 2 parts of a crosslinking aid (triallyl isocyanurate) were added respectively and mixed and dispersed by a paint shaker to obtain a conductive paint.

The roller body obtained in Example 1 was dipped in the above coating composition, pulled up and dried to form a film on the outer surface of the roller body.

Next, the film forming roller body was irradiated with an electron beam of 10 Mrad by the electron beam irradiation apparatus used in Example 1. The irradiation was carried out three times by changing the direction of the roller body from one direction so that a uniform dose was irradiated in the circumferential direction.

By the above method, the charging roller having the surface layer 2a formed by the coating method and cross-linked by the electron beam was completed.

Table 10 shows the results of the durability test of the charging roller.

[0133]

(Comparative Example 5) A charging roller was completed in the same manner as in Example 6 except that the crosslinking aid (triallyl isocyanurate) was not added to the conductive paint and the electron beam was not irradiated. Let

Table 11 shows the durability test results of the charging roller.

[0136]

(Example 7) Chlorinated polyethylene (manufactured by Showa Denko KK, trade name: Eraslen 402ANA) was dissolved in toluene to obtain a solution having a solid content of 5% by weight. To this, a conductivity-imparting agent (manufactured by Ishihara Sangyo Co., Ltd., trade name: conductive tin oxide SN-100) was added at a ratio of 30 parts to 100 parts of chlorinated polyethylene, and mixed and dispersed by a paint shaker to conduct electricity. I got a paint.

The roller body obtained in Example 1 was dipped in the above-mentioned conductive paint, pulled up and dried to form a film on the outer surface of the roller body.

Next, Example 6 was applied to the film forming roller body.
The charging roller was completed by irradiating it with an electron beam in the same manner as in.

Table 12 shows the results of the durability test of the charging roller.

[0141]

(Comparative Example 6) A charging roller was completed in the same manner as in Example 7 except that the electron beam was not irradiated.

Table 13 shows the results of the durability test of the charging roller.

[0144]

[0145]

As described above, the contact charging member according to the present invention has good surface smoothness and excellent durability and environmental resistance.

Also, the contact charging member can be easily manufactured by the manufacturing method of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a general transfer type electrophotographic apparatus using a contact charging member of the present invention.

FIG. 2 is a configuration diagram of an electron beam irradiation apparatus used in the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masaaki Takenaka 1888-2 Kukizaki, Kukizaki-cho, Inashiki-gun, Ibaraki Canon Inc.

Claims (16)

[Claims] 1. A contact charging member which is brought into contact with the surface of an object to be charged and which applies a voltage to charge the object to be charged, wherein the charging member has an elastic layer and a surface layer on a power supply electrode layer, A contact charging member, wherein the surface layer has a crosslinked polymer crosslinked by an electron beam. 2. The contact charging member according to claim 1, wherein the surface layer is a seamless tube formed of a crosslinked polymer. 3. The contact charging member according to claim 1, wherein the surface layer is a layer formed by irradiating the crosslinkable polymer coated on the elastic layer with an electron beam. 4. The contact charging member according to claim 1, wherein the crosslinked polymer is crosslinked polyethylene. 5. The contact charging member according to claim 1, wherein the crosslinked polymer is crosslinked nylon 12 or nylon 11. 6. The contact charging member according to claim 1, wherein the crosslinked polymer is a crosslinked ethylene-acrylic rubber. 7. The contact charging member according to claim 1, wherein the crosslinked polymer is crosslinked polypropylene. 8. The contact charging member according to claim 1, wherein the crosslinked polymer is crosslinked chlorinated polyethylene. 9. The crosslinked polymer is crosslinked epichlorohydrin-
The contact charging member according to claim 1, which is an ethylene oxide rubber. 10. The contact charging member according to claim 1, wherein the crosslinked polymer is crosslinked chlorosulfonated polyethylene. 11. The contact charging member according to claim 1, wherein the crosslinked polymer is a crosslinked modified nitrile rubber. 12. A method of manufacturing a contact charging member, comprising: contacting a surface of an object to be charged and applying a voltage to charge the object to be charged; (1) forming an elastic layer on a power supply electrode layer; (2) a step of forming a film of the polymer in the form of a seamless tube, (3) a step of electron beam cross-linking the polymer forming the seamless tube, and (4) a step of elastically connecting the cross-linked seamless tube. And a step of covering the layer with the layer. 13. An electrophotographic apparatus having a contact charging member and an electrophotographic photosensitive member, wherein the charging member has an elastic layer and a surface layer on a power supply electrode layer, and the surface layer is crosslinked by an electron beam. An electrophotographic apparatus comprising a polymer. 14. The electrophotographic apparatus according to claim 13, wherein the surface layer is a seamless tube formed of a crosslinked polymer. 15. A process cartridge in which an electrophotographic photosensitive member and a charging member are integrally formed into a cartridge and which can be attached to and detached from an image forming apparatus main body, wherein the charging member has an elastic layer and a surface layer on a power supply electrode layer. The surface layer is
A process cartridge having a crosslinked polymer crosslinked by an electron beam. 16. The process cartridge according to claim 15, wherein the surface layer is a seamless tube formed of a crosslinked polymer.