JP2002116607A - Electrostatic charging member, method of manufacturing electrostatic charging member as well as process cartridge and electrophotographic device having this electrostatic charging member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charging member which is uniform in electrostatic charges and makes it possible to obtain good images for a long period, a method of manufacturing the electrostatic charging member as well as a process cartridge and electrophotographic device having this electrostatic charging member. SOLUTION: The electrostatic charging member characterized in that the electrostatic charging member having an arbor 1, a foamed elastic body layer 2 on the outer periphery of the arbor and a seamless tube of plural functional layers 3 on the outer periphery of this foamed elastic body layer 2 is formed by coating the outer periphery of the foamed elastic body layer with the seamless tube of Δd=[(d1-ds)/ (d1+ds)/2}]×100 and this Δd is 0%<=Δd<10% when the ratio of the difference between the major axis d1 and minor axis ds of the sectional shape in the state of the seamless tube to the simple average value of the major axis and the minor axis is defined as Δd and that the ratio (peripheral direction unevenness) Imax/Imin of the maximum current Imax and minimum current Imin in the peripheral direction is <=2.0 times, the method of manufacturing the electrostatic charging member as well as the process cartridge and electrophotographic device having the electrostatic charging member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging member, a method for manufacturing the charging member, a process cartridge having the charging member, and an electrophotographic apparatus. The present invention relates to a charging member for charging the member to be charged, a method for manufacturing the charging member, a process cartridge having the charging member, and an electrophotographic apparatus.

[0002]

2. Description of the Related Art In recent years, as a charging means used in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, a charging means of a contact charging system has been adopted. Contact charging is to charge a charged body to a predetermined polarity and potential by applying a voltage to a charging member arranged in contact with the charged body, and it is possible to lower the voltage of a power supply, such as ozone. There are advantages that the generation of corona products can be reduced, the structure is simple and the cost can be reduced.

[0003] The voltage applied to the charging member has a peak not less than twice the charging start voltage of the member to be charged when a DC voltage is applied to the contact charging member, in addition to the method of applying only DC (DC application method). A method of forming an oscillating electric field having an inter-voltage (an electric field whose voltage value changes periodically with time) between a contact charging member and a charged body to charge the surface of the charged body (AC
Application method), and the latter can provide more uniform charging.

Further, the contact charging device is based on a roller type charging device using a charging member as a roller-shaped member (charging roller) (Japanese Patent Laid-Open Publication No. Sho 63-163).
7380 and JP-A-56-91253, etc., and a blade type charger (JP-A-64-24264 and JP-A-56-91253) as a blade-shaped member (charging blade).
No. 194,349) and a brush type charger (eg, Japanese Patent Application Laid-Open No. 64-24264) using a brush-like member (charging brush).

[0005] The charging roller is rotatably supported by a bearing and pressed against the member to be charged at a predetermined pressure, and is rotated by the movement of the member to be charged.

The above-mentioned charging roller is usually a multilayer having a core provided as a base, a conductive elastic layer provided in a roller shape on the outer periphery of the core, and a surface layer provided on the outer periphery. It is a structure.

[0007] Among the above layers, the core metal (metal layer) is a rigid body for maintaining the shape of the roller and also has a role as a power supply electrode.

[0008] The elastic layer usually has a thickness of 10 ⁴ to 10 ^9.
Since it is required to have a volume specific resistance of Ω · cm and a function of ensuring uniform contact with the member to be charged by elastically deforming, usually, rubber hardness provided with conductivity (JIS-A) Vulcanized rubber having a flexibility of 70 degrees or less is used. Conventional charging rollers include a foam type using a rubber foam (or sponge-like rubber) as an elastic layer and a solid type using no rubber foam.

The surface layer improves the charging uniformity of the member to be charged, prevents the occurrence of leaks due to pinholes or the like on the surface of the member to be charged, and also prevents the adhesion of toner particles and paper powder. And a function of preventing bleeding of a softening agent such as an oil or a plasticizer used for lowering the hardness of the elastic layer. The volume resistivity of the surface layer is usually 10 ⁵ to 10 ¹³ Ω · cm, and has conventionally been formed by applying a conductive paint or covering a seamless tube.

[0010] In the seamless tube manufacturing apparatus, the seamless tube is extruded by the extrusion means, and the air cooling means,
The seamless tube is manufactured in the order of the water-cooling sizing means and the tube taking-off means.However, in the case of the tube taking-off means, the seamless belt is slipped unless the gap of the taking-off belt is smaller than the outer diameter of the seamless tube. The tube was crushed and taken off. Therefore, there is a problem that the cross-sectional shape of the tube becomes elliptical.

[0011]

In the case of a charging roller whose roller roundness has not been obtained, unevenness in the circumferential direction of charging may occur. The problem is that the cross-sectional shape of the seamless tube to be coated is not a perfect circle, but rather an ellipse. When covering the seamless tube, the oval shape of the seamless tube affects the soft foam elastic layer, and the roller shape after coating is Was considered to have occurred due to the oval shape following the oval shape of the seamless tube.

SUMMARY OF THE INVENTION An object of the present invention is to provide a charging member in which the cross-sectional shape of a seamless tube coated on a soft foamed elastic layer is close to a perfect circle, minimizing the occurrence of circumferential unevenness, a method of manufacturing the charging member, and a method of manufacturing the charging member. An object of the present invention is to provide a process cartridge having a member, and an electrophotographic apparatus incorporating the process cartridge.

[0013]

According to the present invention, there is provided a charging member having a cored bar, a foamed elastic layer on the outer periphery of the cored bar, and a functional multilayer seamless tube on the outer periphery of the foamed elastic layer. When the ratio of the major axis and minor axis of the difference between the major axis dl and the minor axis ds of the cross-sectional shape in the state of the seamless tube to the simple average value is Δd, Δd = [(dl−d
s) / {(dl + ds) / 2}] × 100.
A charging member in which a seamless tube in which d satisfies 0% ≦ d <10% is coated on the outer periphery of the foamed elastic layer, and a ratio (circumferential unevenness) between a maximum current Imax and a minimum current Imin in the circumferential direction I
Provided is a charging member characterized in that max / Imin is 2.0 times or less.

Further, according to the present invention, in the method for manufacturing a charging member having a cored bar, a foamed elastic layer on the outer periphery of the cored bar, and a plurality of seamless tubes on the outer periphery of the foamed elastic layer, The gap width of the take-up belt of the take-up means for taking the tube is 0.85 times the outer diameter of the tube.
The present invention provides a method for manufacturing a charging member, wherein the seamless tube is taken up by a take-up means that is one-time and the take-up belt has at least a foam layer.

According to the present invention, in a process cartridge which integrally supports an electrophotographic photosensitive member and at least a charging member and is detachable from an electrophotographic apparatus main body, a voltage having at least an AC component is applied to the charging member. A charging member for charging the electrophotographic photosensitive member by bringing the charging member into contact with the electrophotographic photosensitive member, wherein the charging member is the charging member.

Further, according to the present invention, an electrophotographic photoreceptor,
In an electrophotographic apparatus having a charging member, an exposure unit, a developing unit, and a transfer unit, the charging unit contacts the electrophotographic photosensitive member with a charging member to which a voltage having at least an AC component is applied. An electrophotographic apparatus is provided, which is a charging member for charging a photoreceptor, wherein the charging member is the charging member.

[0017]

Embodiments of the present invention will be described below in more detail.

FIG. 1 shows an example of a charging member (hereinafter, also referred to as a charging roller) 1 'of the present invention, which is used as a charger of an electrophotographic apparatus. This charging roller is
A foamed elastic body layer 2 made of a conductive elastic material is provided on the outer periphery of a cored bar 1 made of a good conductive material such as stainless steel, plated iron, brass, and conductive plastic. The outer periphery is covered with a tubular functional multilayer film 3. In the case of FIG. 1, the functional multilayer film includes an inner layer 3 (i) and an outer layer 3 (o).

Here, as the conductive elastic material constituting the foamed elastic layer 2, a foamed conductive rubber composition containing a conductive material or a conductive polyurethane foam can be used.

In this case, the rubber component constituting the foamed conductive rubber composition is not particularly limited, but
Ethylene-propylene-diene rubber (EPDM), chloroprene, chlorosulfonated polyethylene blended with conductive material, foam, copolymer rubber of epichlorohydrin and ethylene oxide, or copolymer rubber of epichlorohydrin and ethylene oxide A foam containing a conductive material can be suitably used.

Examples of the conductive material to be added to these rubber compositions include conductive powders such as carbon black, graphite, metal and various conductive metal oxides (such as tin oxide and titanium oxide), carbon fiber and metal oxide. Various conductive fibers such as short fibers of the product can be used. The compounding amount is preferably 3 to 100 parts by mass, particularly preferably 5 to 50 parts by mass with respect to 100 parts by mass of the total rubber component, whereby the volume resistance of the foamed elastic layer 2 is 10 to 10 ⁹ Ω · It is preferable to adjust to about cm. The foamed elastic layer 2 can be formed by a known vulcanization molding method.
The thickness is appropriately set according to the use of the charging roller and the like, but is usually preferably 1 to 20 mm.

In the present invention, a functional multilayer film 3 is coated on the foamed elastic layer 2 in the form of a tube. In this case, the thermoplastic resin constituting the functional multilayer film 3 may be any thermoplastic resin that can be extruded, and specifically, ethylene propylene rubber (E
PDM), ethylene vinyl acetate, ethylene ethyl acrylate, ethylene methyl acrylate, styrene butadiene rubber, polyester, polyurethane, polyamide (nylon 6, nylon 66, nylon 11, nylon 12)
And other copolymerized nylons), styrene ethylene butyl, ethylene butyl, nitrile butadiene rubber, chlorosulfonated polyethylene, polysulfide rubber, chlorinated polyethylene, chloroprene rubber, butadiene rubber, 1,2-
Conventional rubbers such as polybutadiene, isoprene rubber and polynorbornene rubber, and thermoplastic rubbers such as styrene-butadiene-styrene (SBS) and styrene-butadiene-styrene water additive (SEBS) can be used, with particular limitations. It is not something to be done.

Alternatively, elastomers such as the above-mentioned resins and copolymers and modified elastomers, and polyethylene, polypropylene, polyethylene terephthalate (PET) and polybutylene terephthalate (PBT)
Such as saturated polyester, polyether, polyamide, polycarbonate, polyacetal, acrylonitrile butadiene styrene, polystyrene, high impact polystyrene (HIPS), polyurethane, polyphenylene oxide, polyvinyl acetate, polyvinylidene fluoride,
Polytetrafluoroethylene, acrylonitrile-butadiene-styrene resin (ABS), acrylonitrile-
Ethylene / propylene rubber-styrene resin (AES) and acrylonitrile-acrylic rubber-styrene resin (A
A combination of a styrene resin such as AS) and each resin such as an acrylic resin, a vinyl chloride resin and a vinylidene chloride resin, and a material composed of a copolymer is preferable.

As the core metal (metal layer) in the present invention,
For example, a good conductor such as aluminum, copper, iron, or an alloy containing these is preferably used. The metal core used in the present invention may be a metal tube having a thickness of about 0.1 to 1.5 mm or a rod.

Next, the functional multilayer film used in the present invention will be described. The functional multilayer film in the present invention is a polymer formed in a form of a seamless tube in advance, and is externally fitted to the foamed elastic material layer on the outer periphery of the metal core (metal layer), and is tightly covered. .

The resin, elastomer, copolymer and the like used in this case are as described above, and a tube structure having desired characteristics can be obtained by appropriately blending a conductive material and the like described later.

Further, a polymer alloy or a polymer blend comprising two or more kinds of polymers selected from the above rubbers, thermoplastic elastomers and thermoplastic resins can also be used.

The tube of the functional multilayer film of the present invention is prepared by extrusion molding, injection molding and blow molding of the above polymer and a conductive polymer composition comprising the following conductive material and, if necessary, other additives. It can be obtained by forming a film into a tube by a molding method or the like. Among the above various molding methods,
Extrusion molding is particularly preferred.

Further, in order to obtain a uniform thickness of each thin film layer of the formed tube and a more uniform dispersibility of the conductive material, a vertical tube extruder (FIG. 2) is used. I do.

As the conductive material, known materials can be used, for example, carbon fine particles such as carbon black and graphite; metal fine particles such as nickel, silver, aluminum and copper; tin oxide, zinc oxide, titanium oxide, and the like. Conductive metal oxide fine particles containing aluminum oxide and silica as main components and doped with impurity ions having different valences; conductive fibers such as carbon fibers; metal fibers such as stainless steel fibers; carbon whiskers and potassium titanate whiskers Conductive whisker such as conductive potassium titanate whisker whose surface is made conductive with metal oxide or carbon; and conductive polymer fine particles such as polyaniline and polypyrrole.

The tube of the functional multilayer film used in the present invention can be used simply by being formed by the above-mentioned various molding methods. For example, in order to obtain more excellent durability and environmental resistance, the above-mentioned tube is used. The seamless tube obtained by various molding methods can be further crosslinked to obtain a conductive crosslinked polymer. As a method for cross-linking a conductive polymer formed in a tubular shape, a cross-linking agent such as sulfur, an organic peroxide and an amine is added in advance depending on the type of the polymer, and cross-linking is performed at a high temperature. Is effective, and a radiation cross-linking method of cross-linking by irradiation with radiation such as an electron beam or γ-ray is effective. Among the above various crosslinking methods, the electron beam crosslinking method is preferable in that there is no risk of contamination of the member to be charged due to transfer of a crosslinking agent or a decomposition product thereof, and further, there is no need for high-temperature treatment and safety.

Next, a method for manufacturing a tube will be described.

The tubes of the functional multilayer film 3 composed of an even number can be formed by various methods, but the extrusion molding method is preferable as described above. That is, as shown in FIG. 2, a polymer and a conductive material, and if necessary, a crosslinking agent,
A compound is prepared by mixing a stabilizer and other additives, and the compound is extruded from the die 4 having a ring-shaped slit into the central through-hole 5 by extruders 8 and 9, and cooled by a water-cooled ring 10. A seamless tube can be manufactured. In FIG.
3 is a seamless tube of a functional multilayer film, 11 is a timing pulley of a tube take-up device, and 12 is a take-up belt.

As shown in FIG. 5, the cross-sectional shape of the seamless tube tends to be roughly determined by the size relationship between the gap width of the feed belt applied to the timing pulley of the tube take-up device and the outer diameter of the seamless tube.

When the gap width of the take-up belt is larger than the outer diameter of the seamless tube, it is difficult to manufacture the seamless tube because the seamless tube cannot be transported. Conversely, if it is too small, the seamless tube will be crushed and sent, and its shape change will affect the roller shape after coating in the next step. That is, if the seamless tube is significantly crushed, the perfect circle of the finished product roller is greatly damaged, and an abnormal image may be generated (not shown).

More specifically, when the average outer diameter of the seamless tube is less than 0.95 times, the seamless tube is liable to be crushed and Δd tends to be 10% or more. If the ratio is 1.1 times or more, the tube may not be transported smoothly, and a stable tube may not be obtained. However, even if the ratio is less than 0.95 in the above relationship, a restoring force acts on the seamless tube when the seamless tube comes out of the area of the take-off belt. Depending on the material of the seamless tube, it can be up to 0.85 times. That is, in the present invention,
The gap width of the take-up belt of the take-up means for taking out the seamless tube is 0.85 to 1.1 times, preferably 0.95 to 1.1 times, the outer diameter of the tube.

If the gap width of the take-up belt is slightly larger than the outer diameter of the seamless tube, the take-up belt may swing due to the movement of the take-up belt. It is. In other words, when the belt surface has large irregularities or has good adhesion to the seamless tube, the relationship between the take-up belt gap width and the outer diameter of the seamless tube can be increased. . In particular, when the take-up belt has a foam layer, the conveyance can be effectively performed. That is, the hardness of the foam layer of the take-up belt is low,
The more the foam cell structure is exposed on the surface, the more effective it is (see FIG. 6).

If the ratio of the major axis and minor axis of the difference between the major axis dl and minor axis ds of the cross-sectional shape of the drawn seamless tube to the simple average is Δd, then Δd = [(dl−ds)
/ {(Dl + ds) / 2}] × 100, and the maximum current I in the circumferential direction is a charging member in which a seamless tube in which the Δd is 0% ≦ Δd <10% is coated on the outer periphery of the foamed elastic material layer.
ratio (maximum unevenness in the circumferential direction) Imax between the maximum current and the minimum current Imin
When / Imin is 2.0 times or less, a good image can be obtained. When Δd ≧ 10, the charging roller covered with the seamless belt having a cross-sectional shape that is not a perfect circle but rather an ellipse has an elliptical shape, the charging is not uniform, and the circumferential maximum current Imax and the minimum current Imin The ratio (maximum in the circumferential direction) Imax / Imin exceeds 2.0 times to cause image defects. Further, even if 0% ≦ Δd <10%, if the circumferential unevenness exceeds 2.0 times, an image defect due to non-uniform charging occurs.

The seamless tube used in the present invention may be either non-heat-shrinkable or heat-shrinkable.
In the embodiment, a non-heat-shrinkable material is employed.

In the case of a non-heat-shrinkable tube, it is necessary that the inner diameter of the tube be equal to or less than the outer diameter of the foamed elastic layer in order to secure adhesion to the foamed elastic layer. When the tube diameter is enlarged by blowing compressed air, the tube is inserted into the foamed elastic body layer having the metal core and the air pressure is released to complete the external fitting process.

FIG. 3 shows a schematic configuration of an electrophotographic apparatus incorporating the roller-shaped charging member 1 'provided with the functional multilayer film thus formed.

In FIG. 3, a drum-shaped electrophotographic photosensitive member 1
3 (hereinafter referred to as a photosensitive drum) is driven to rotate at a predetermined peripheral speed in the direction of the arrow. In the rotation process, the photosensitive drum 13 receives a uniform charge of a predetermined positive or negative potential on its peripheral surface by the charging member 1 ′, and then receives an image from an exposure unit (not shown) such as slit exposure or laser beam scanning exposure. The exposure light 15 is received. Thus, an electrostatic latent image is sequentially formed on the peripheral surface of the photosensitive drum 13.

The formed electrostatic latent image is then transferred to developing means 1
The toner image developed by the toner transfer device 6 is transferred from a paper feeding unit (not shown) between the photosensitive drum 13 and the transfer unit 18 in synchronization with the rotation of the photosensitive drum 13 and fed. The image data is sequentially transferred to the transfer device 21 by the transfer means 18.

The transfer material 21 having undergone the image transfer is separated from the photosensitive drum surface, introduced into the image fixing means, and subjected to image fixing to be printed out of the apparatus as an image formed product (print copy).

The surface of the photosensitive drum 13 after the transfer is cleaned and cleaned by removing the untransferred toner by the cleaning means 17, and is used repeatedly for image formation.

A plurality of components such as the photosensitive drum 13, the charging member 1 ', the developing means 16 and the cleaning means 17 are integrally connected as a process cartridge. It may be configured to be detachable from an electrophotographic apparatus main body such as a laser beam printer. For example, the developing unit 16 and the cleaning unit 17 are integrally supported together with the photosensitive drum 13 and the charging member 1 ′ to form a cartridge, and a process cartridge detachable from the apparatus main body by using a guide unit such as a rail of the apparatus main body. Can be.

When the electrophotographic apparatus is a copier or a printer, the exposure light 15 is reflected or transmitted from the original, or the original is read by a sensor and converted into a signal.
Laser beam scanning performed according to this signal,
The light is emitted by driving the LED array or driving the liquid crystal shutter array.

The above apparatus is used for evaluation and the like as a process cartridge incorporating a charging member coated with a tube formed by the apparatus of the present invention, and further as an electrophotographic apparatus incorporating the same.

[0049]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples.

A charging roller is manufactured as follows.

<Core Metal> A core metal was prepared by extruding an iron material into a bar having a diameter of about 5 mm by extrusion, cutting the bar to a length of 260 mm, and applying a chemical plating to a thickness of about 3 μm.

<Formation of Foamed Elastic Material Layer>
A hose-shaped foamed elastic material layer having an outer diameter of 11.5 mm: A vulcanizing agent and a foaming agent are blended with ethylene-propylene-diene rubber (EPDM), and the mixture is formed into a hose shape by an extruder, Foamed in a vulcanizer can be length 2
Cut into 25mm, the center hole, the above-mentioned diameter 5mm,
A core bar having a length of 260 mm was inserted.

<Formation of tube of functional multilayer film> As a material of the outer layer of the functional multilayer film, a styrene resin (styrene-ethylene / butylene-olefin copolymer resin, trade name: Dinalon, Nippon Synthetic Rubber Co., Ltd.) 100 parts by mass, polyethylene 20 parts by mass and carbon black (trade name:
15 parts by mass of Ketchen Black EC (manufactured by Lion Akzo) were mixed for several minutes in a V-type blender. This further
The mixture was melt-kneaded at 190 ° C. for 10 minutes using a pressure kneader. Furthermore, after cooling, it was pulverized by a pulverizer and pelletized by a single screw extruder.

As the material of the inner layer, 100 parts by mass of a polyurethane elastomer, 15 parts by mass of carbon black (Ketjen Black EC), 10 parts by mass of magnesium oxide and 1 part by mass of calcium stearate were pelletized in the same process as the material of the outer layer. It has become.

Using a vertical extruder (a custom-made product manufactured by Plagiken Co., Ltd., see FIG. 3), these are combined into a double layer with one crosshead, and hot water at an appropriate temperature (40 ° C. to 90 ° C.) )
Was extruded into a water-cooled ring 10 containing the water, and was further cooled and taken out (11 and 12). Thus, the outer diameter of about 12
mm of a functional multilayer film tube was obtained. A tube obtained by cutting this functional multilayer tube into a length of 230 mm was fitted around the outer periphery of the foamed elastic layer by a tube covering device (not shown) and brought into pressure-contact with each other.

The sectional shape of the seamless tube is as follows.
It was measured by the following method. The major axis dl and the minor axis ds are measured by using a measuring device such as a projector, a video micro, or the like that can measure the cross section by cutting the cross section in the seamless tube state.

Assuming that the ratio of the difference between the major axis dl and the minor axis ds of the sectional shape in the seamless tube state to the simple average value of the major axis and the minor axis is Δd, Δd = [(dl−ds) / ｛(dl + ds) / 2｝] × 1
00.

(Examples 1-1 to 1-3) The following Δ
d was extruded and taken up with a take-up belt having a foam layer. Example 1-1 Δd = 1.6 Example 1-2 Δd = 5.0 Example 1-3 Δd = 9.9

In Examples 1-1, 1-2 and 1-3, Δd
Is a seamless tube in which 0% ≦ Δd <10%. Next, this seamless tube was coated on the foamed elastic material layer by a tube coating device to prepare a charging roller.

The circumferential resistance of the charging roller was measured by the following method. That is, as shown in FIG. 7, a load of 1 kg (end load 0.5 kg ×) is applied to a φ30 mm mirror-finished metal roll (SUS or the like) rotating the charging roller 1 ′ at 30 rpm.
2) contact, AC500Vpp (300Hz), D
C-200V is applied. At that time, the maximum current Imax and the minimum current Imin of the third rotation of the charging roller flowing through the metal roll were measured, and the circumferential unevenness was calculated. The circumferential unevenness of the charging roller measured as described above was 2.0 times or less.

An image was formed by using this charging roller as a primary charger of an LBP (laser beam printer; Laser Jet 2-P manufactured by Hewlett-Packard Company). As a result, a gap between the functional multilayer film and the foamed elastic layer was obtained. A good image was obtained without wrinkling of the functional multilayer film probably because there was no gap.

Next, the charging roller is mounted on a cartridge (trade name: EP-L, manufactured by Canon Inc.), and the cartridge is mounted on a laser beam printer (trade name: Laser).
Shot A404, manufactured by Canon Inc.)
Output 3500 images under the environment of ℃ / 50% RH,
As a result of visually evaluating the image quality of the output image, no abnormality was recognized.

(Comparative Examples 1-1 and 1-2) A seamless tube different from that of Example 1 in the following points was prepared, and the same evaluation was performed. Comparative Example 1-1 Δd = 13.2 Comparative Example 1-2 Δd = 19.8

Table 1 shows the results of Example 1 and Comparative Example 1.

[0065]

[Table 1]

As is apparent from the above results, in order to output a good halftone image on a roller having a sponge base layer coated with a tube, the difference between the major axis and the minor axis of the cross-sectional shape of the tube before coating is required. In the charging roller in which the ratio of the major axis and the minor axis to the simple average value Δd is 0% ≦ Δd <10%, the unevenness in the circumferential direction needs to be 2.0 times or less in the charging roller in which the seamless tube is coated with the foamed elastic material layer. Do you get it.

(Examples 2-1 to 2-3) In Example 1, a seamless tube was extruded using a vertical extruder capable of changing the belt gap width with respect to the tube outer diameter as follows, and a foam layer was provided. A charging roller was produced in the same manner as in Example 1, except that the charging roller was taken off by a take-up belt. -Example 2-1 Belt gap width with respect to tube outer diameter
Example 2-2 Belt gap width with respect to tube outer diameter
1.0 times ・ Example 2-3 Belt gap width with respect to tube outer diameter
1.1 times

(Comparative Examples 2-1 and 2-1) A seamless tube different from that of Example 2 in the following points was prepared and subjected to the same evaluation. Comparative Example 2-1 Belt gap width with respect to tube outer diameter
0.8 times Comparative Example 2-2 Belt gap width with respect to tube outer diameter
It is 1.2 times.

Table 2 shows the results of Example 2 and Comparative Example 2.

[0070]

[Table 2]

[0071]

As described above, according to the present invention, it is possible to manufacture a charging member in which the cross-sectional shape of the tube covered with the foamed elastic material layer is close to a perfect circle, and the occurrence of circumferential unevenness can be suppressed as much as possible. It became possible to provide a method. Furthermore,
It has become possible to provide a charging member capable of obtaining a good image with uniform charging for a long period of time, and a process cartridge and an electrophotographic apparatus having the charging member.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of an example of a charging member of the present invention.

FIG. 2 is a schematic longitudinal sectional front view of a vertical extruder corresponding to various multilayers of a seamless tube having a plurality of functional films of the present invention.

FIG. 3 is a schematic view of an electrophotographic apparatus having the charging roller of the present invention.

FIG. 4 is a schematic view of a process cartridge on which the charging roller of the present invention is mounted.

FIG. 5 is a drawing showing a gap between a width of a take-off belt of a take-up means for a seamless tube used in the present invention, and a cross-sectional view of the seamless tube.

FIG. 6 is a sectional view of a take-off belt used in the present invention.

FIG. 7 is a schematic diagram of a charging roller resistance measuring device used in the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 core metal (metal layer) 1 ′ charging member (charging roller) 2 foamed elastic layer 3 functional multilayer film 4 die 5 central through hole 6, 7 extrusion flow path 8 first extruder 9 second extruder 10 water cooling ring REFERENCE SIGNS LIST 11 timing pulley (tube take-up unit) 12 take-up belt (tube take-up unit) 13 charged body (photosensitive drum) 14 power supply 15 exposure light 16 developing device 17 cleaning device 18 transfer device 20 rail 21 transfer material 22 fixing Apparatus 23 Process cartridge 24 Metal roll 25 High voltage power supply 26 Pulse oscillator 27 Low pass FNF circuit 28 DMM (Digital multimeter) 29 Personal computer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuyuki Shishizuka, 1888-2 Kusazaki, Kusazaki-cho, Inashiki-gun, Ibaraki Prefecture Within Canon Chemical Co., Ltd. F-term in Kasei Co., Ltd. (Reference) 2H003 AA11 BB11 CC05 3J103 AA02 AA15 AA33 AA51 AA69 BA41 EA02 EA08 FA12 FA15 FA18 GA02 GA52 GA57 GA58 GA60 HA03 HA04 HA05 HA12 HA15 HA18 HA32 HA36 HA37 HA42 HA44 HA45 HA46 HA48 HA53

Claims (5)

[Claims] 1. A charging member having a cored bar, a foamed elastic layer on the outer periphery of the cored bar, and a seamless tube of a plurality of functional layers on the outer periphery of the foamed elastic layer, the charging member having a state of the seamless tube. Δd = [(dl−ds) / {(dl + ds) / 2}] × 10, where Δd is the ratio of the major axis and minor axis of the difference between the major axis dl and the minor axis ds of the sectional shape to the simple average value.
0, a charging member in which a seamless tube in which the Δd is 0% ≦ Δd <10% is coated on the outer periphery of the foamed elastic layer, and a ratio (maximum unevenness in the circumferential direction) Imax between the maximum current Imax and the minimum current Imin in the circumferential direction. / Imin is 2.0 times or less. 2. A method for manufacturing a charging member having a cored bar, a foamed elastic layer on the outer periphery of the cored bar, and a plurality of seamless tubes on the outer periphery of the foamed elastic layer, wherein the seamless tube is taken off. The width of the gap of the take-off belt of the take-up means is 0.85 to 1.1 times the outer diameter of the tube, and the take-up belt has at least a foam layer. A method for manufacturing a charging member, wherein the charging member is taken off. 3. The method for manufacturing a charging member according to claim 3, wherein the gap width of the take-off belt is 0.95 to 1.1 times the outer diameter of the tube. 4. A process cartridge which integrally supports an electrophotographic photosensitive member and at least a charging member and is detachable from an electrophotographic apparatus main body, wherein the charging member is a charging member to which a voltage having at least an AC component is applied. A process cartridge, which is a charging member for charging the electrophotographic photosensitive member by contacting the electrophotographic photosensitive member, wherein the charging member is the charging member according to claim 1. 5. An electrophotographic photosensitive member, a charging member, an exposure unit,
In an electrophotographic apparatus having a developing unit and a transfer unit,
The charging member is a charging member that charges the electrophotographic photosensitive member by bringing the charging member to which a voltage having at least an AC component is applied into contact with the electrophotographic photosensitive member,
An electrophotographic apparatus, wherein the charging member is the charging member according to claim 1.