JP2007101614A - Method for manufacturing coated tube for charging member, coated tube for charging member, charging member, cartridge for electrophotographic apparatus, and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging member which obviates the occurrence of an image defect due to resistance unevenness and shape unevenness by using a means for taking off a tube without touching the use part of the tube, a cartridge for an electrophotographic apparatus mounted with the charging member, and an electrophotographic apparatus. <P>SOLUTION: The method for manufacturing the coated tube for the charging member in which the take-off unit of the coated tube for the charging member consists of two vertically moving chuck mechanisms and a conveyance means for taking off the tubes downward while alternately gripping the tubes is used and the tube are provided. The charging member produced in the manner described above, the cartridge for the electrophotographic apparatus subjected to application expansion and the electrophotographic apparatus are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charging member that is placed in contact with a member to be charged and charges the member to be charged when a voltage is applied thereto, and a method of manufacturing the coated tube. The present invention also relates to an electrophotographic cartridge having the charging member and an electrophotographic apparatus.

  In recent years, a contact charging type charging unit has been adopted as a charging unit used in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus.

  Contact charging is to charge a charged body to a predetermined polarity and potential by applying a voltage to a charging member disposed in contact with the charged body.

  Therefore, there are advantages that the voltage of the power source can be lowered, the generation of corona products such as ozone can be reduced, the structure is simple, and the cost can be reduced.

  There is a method in which only a direct current is applied to the charging member (DC application method). Other than this, an oscillating electric field having a peak-to-peak voltage that is at least twice the charging start voltage of the charged body when a DC voltage is applied to the contact charging member is formed between the contact charging member and the charged body. There is a method (AC application method) for charging the surface of a member to be charged. An oscillating electric field refers to an electric field whose voltage value periodically changes with time.

  The AC application method can perform more uniform charging than the DC application method.

  The contact charging device is roughly classified into the following three types depending on the shape and form of the charging member brought into contact with the member to be charged.

  A roller-type charger using a charging member as a roller-like member (charging roller), a blade-type charger using a blade-like member (charging blade), a brush-type charger using a brush-like member (charging brush), etc. (For example, see Patent Documents 1 to 4).

  The charging roller is rotatably supported by the bearing, is brought into pressure contact with the member to be charged at a predetermined pressure, and rotates as the member to be charged moves.

  The charging roller is usually a multilayer structure having a cored bar provided at the center as a substrate, a conductive elastic layer provided in a roller shape on the outer periphery of the cored bar, and a surface layer provided on the outer periphery thereof. .

  Of the above layers, the cored bar (metal layer) is a rigid body for maintaining the shape of the roller and has a role as a feeding electrode.

The elastic layer usually has a volume resistivity of 10 ⁴ to 10 ⁹ Ω · cm and a function of ensuring uniform contact with the member to be charged by elastic deformation. For this reason, a vulcanized rubber having a flexibility of 70 degrees or less is generally used.

  The conventional charging roller includes a foam type using a rubber foam (or sponge-like rubber) as an elastic layer and a solid type not using a rubber foam.

  In addition, the surface layer has a function of improving the charging uniformity of the object to be charged, preventing leakage due to pinholes on the surface of the object to be charged, and preventing adhesion of toner particles and paper powder. is doing.

  It also has a function of preventing bleeding of softeners such as oil and plasticizer used to reduce the hardness of the elastic layer.

The volume resistivity of the surface layer is usually 10 ⁵ to 10 ¹³ Ω · cm, and conventionally formed by applying a conductive paint or covering a seamless tube (for example, see Patent Document 5). ).

  At the time of forming the seamless tube, the seamless tube was crushed and taken up because the slip would occur unless the take-up belt gap width was smaller than the outer diameter of the tube in the tube take-up step.

  As a result, the cross-sectional shape of the tube becomes elliptical, and there is uneven outer diameter in the circumferential direction (poor roundness is poor), and resistance unevenness occurs in the circumferential direction because the stress applied in the circumferential direction is different. It was loose (uneven circumferential resistance was bad).

  Further, the take-up belt is stretched with a slight slack because the movement of the take-up belt becomes worse when it is taut.

  Since the undulation occurs in the belt due to the tarmi, the tube repeats contact and separation with the take-up belt (FIG. 3A).

  Therefore, a subtle difference in the outer diameter occurs in the longitudinal direction of the seamless tube (poor straightness).

  The roundness, circumferential resistance unevenness, and straightness of these tubes affect the performance of the charging roller after coating.

  In other words, if the roundness, circumferential resistance unevenness, and straightness of the tube are poor, it results in uneven resistance and shape unevenness of the charged roller after coating, and as a result, it is one of the causes of image defects that appear as density unevenness in the image. There was a problem that.

  Therefore, an improvement has been made to a roll-type (FIG. 3B) take-up device, not a belt-type take-up device (see, for example, Patent Document 6).

  By adopting a roll type, the tube is always in contact with the tube at one point and the contact and separation are not repeated, so the straightness of the tube is improved.

  However, there was a backlash due to the delicate backlash in the gear between the take-up roll and the motor. In addition, depending on the surface properties of the tube, the surface of the take-up roll must be covered with rubber to prevent slippage, and its shape accuracy may be low. Therefore, some speed unevenness remained.

  Furthermore, since it is in contact with the tube only at one point, there is a new problem that vibration in the subsequent cutting process is easily transmitted to the tube before the water-cooled sizing process and causes pulsation in the longitudinal direction of the tube.

In addition, the circumferential resistance unevenness is improved because the time during which the tube is crushed is shortened, but the circumferential resistance unevenness is still a problem because it is somewhat crushed to prevent slipping.
JP 56-91253 A JP-A 64-24264 JP 56-194349 A JP-A 64-24264 Japanese Patent Laid-Open No. 11-125952 JP 2003-39523 A

  Accordingly, an object of the present invention is to provide a method of manufacturing a coated tube for a charging member in which unevenness in resistance and unevenness in outer diameter are suppressed by using a means for pulling out without touching the tube use portion, and the tube.

  Furthermore, by providing the tube with an elastic layer to provide a charging member that does not cause image defects due to uneven resistance or uneven shape, or an electrophotographic apparatus cartridge and electrophotographic apparatus equipped with the charging member. There is also.

  The present invention provides a seamless tube having a plurality of layers on an elastic body layer on an outer periphery of a metal core, which includes a step of extruding a tube in a substantially gravitational direction, an air cooling step, a water cooling sizing step, a tube taking step, and a tube cutting step. In the method of manufacturing a charging member-coated tube used as a charging member by coating the tube, the tube take-up step is performed by one chuck mechanism of two chuck mechanisms that alternately move up and down alternately as the tube attaching / detaching means. A step of chucking the tube at a fixed position and pulling the tube downward at a set take-off speed, and a step of the one-side chuck mechanism unchucking the tube at a lower position and returning to an upper fixed position at an appropriate speed; At the timing of the unchuck, the other chuck mechanism chucks the tube at the upper fixed position and the set take-up speed A step of repeating the step of pulling and the step of the other chuck mechanism unchucking the tube at the lower position and returning to the upper fixed position at an arbitrary speed. In the tube cutting step, the chuck mechanism chuck The tube is cut at the position.

In addition, the present invention provides a charging member-coated tube manufactured by the method for manufacturing a charging member-coated tube according to claim 1, wherein the roundness of the tube and the rate of change in resistance unevenness in the circumferential direction before and after the tube take-up step are as follows. Is 1.1 or less and 0.3% or less in straightness Δ / Da × 100.
(Δ is the difference between the maximum value and the minimum value of at least three outer diameter average values in the circumferential direction at the five outer diameter measurement positions in the longitudinal direction of the tube Da is the average value of all outer diameter measurement values)

  According to the present invention, the used portion of the tube does not touch the take-up means and is not crushed, so that the roundness and the circumferential resistance unevenness can be prevented from deteriorating before and after taking-up.

  In addition, since the take-up speed accuracy is improved and vibration during cutting is stopped at the chuck portion, it is possible to provide a method for manufacturing a coated tube for a charging member with excellent straightness and the tube.

  Furthermore, by covering the tube with an elastic layer, it is possible to provide a charging member that does not cause image defects due to uneven shape and uneven resistance, an electrophotographic apparatus cartridge equipped with the charging member, and an electrophotographic apparatus. became.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  According to the present invention, a charging member-covered tube take-up device comprises two chuck mechanisms that move up and down, and the charging member-covering tube manufacturing method using a conveying means that pulls down while alternately gripping the tube, and the tube is there.

  Also, the charging member produced in this manner, and the electrophotographic apparatus cartridge and electrophotographic apparatus that have been applied and developed.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 shows an example of a charging roller which is a charging member 1 'according to the present invention, which is used as a charger of an electrophotographic apparatus.

  In this charging roller, a foamed elastic body layer 2 made of a conductive elastic material is provided on the outer periphery of a core metal 1, and a tubular functional multilayer film (functional multi-layer tube) 3 is provided on the outer periphery of the foamed elastic body layer 2. Is coated. The core 1 is made of a highly conductive material such as stainless steel, plated iron, brass, and conductive plastic.

  In the case of FIG. 1, the functional multi-layer tube is composed of an inner layer 3 (i) and an outer layer 3 (o).

  As the core metal (metal layer) in the present embodiment, 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 embodiment may be a metal tube having a thickness of about 0.1 to 1.5 mm, or may be a rod shape.

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

  In this case, as the rubber component constituting the foamed conductive rubber composition, it is possible to use a foam of ethylene-propylene-diene rubber (EPDM), chloroprene, chlorosulfonated polyethylene or the like containing a conductive material. it can.

  In addition, a foam of a copolymer rubber of epichlorohydrin and ethylene oxide or a foam of a conductive rubber blended with a copolymer rubber of epichlorohydrin and ethylene oxide can also be suitably used.

  The rubber component constituting the foamed conductive rubber composition is not particularly limited to the above.

  Examples of the conductive material to be blended in the rubber composition include conductive powders such as carbon black, graphite, metals and various conductive metal oxides (such as tin oxide and titanium oxide), carbon fibers and short fibers of metal oxides. Various conductive fibers such as can be used.

The blending amount is preferably 3 to 100 parts by weight, particularly preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total rubber component, and thereby the volume resistance of the foamed elastic layer 2 is 10 ¹ to 10 ⁹ Ω. -It is preferable to adjust to about cm.

  The foamed elastic body layer 2 can be formed by a known vulcanization molding method, and the thickness is appropriately set according to the use of the charging roller, but is usually preferably 1 to 20 mm.

In the present embodiment, a functional multilayer film (functional multilayer tube) 3 is coated on the foamed elastic layer 2 in the form of a tube.
In this case, the thermoplastic resin and elastomer constituting the functional multi-layer tube 3 may be any thermoplastic resin and elastomer that can be extruded. Specifically, ethylene propylene rubber (EPDM), ethylene vinyl acetate, ethylene ethyl acrylate, ethylene methyl acrylate, styrene butadiene rubber, polyester, polyurethane, nylon 6, nylon 66, nylon 11, nylon 12, and other copolymer nylons Polyamide, styrene ethylene butyl, ethylene butyl, nitrile butadiene rubber, chlorosulfonated polyethylene, polysulfide rubber, chlorinated polyethylene, chloroprene rubber, butadiene rubber, 1,2-polybutadiene, isoprene rubber and polynorbornene rubber, etc. Thermoplastic rubbers such as rubber, styrene-butadiene-styrene (SBS) and styrene-butadiene-styrene water additive (SEBS) can be used, and are not particularly limited.

  Alternatively, elastomers such as the above-mentioned resins and copolymers and elastomers such as modified products, polyethylene, polypropylene, polyether, polyamide, polycarbonate, polyacetal, polyurethane, polyphenylene oxide, polyvinyl acetate, polyvinylidene fluoride, polytetrafluoro Ethylene; saturated polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polystyrene, high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene resin (ABS), acrylonitrile-ethylene / propylene rubber-styrene resin (AES) And styrene resins such as acrylonitrile-acrylic rubber-styrene resin (AAS), acrylic resins, vinyl chloride resins, vinyl chloride The combination of materials consisting of the resin and copolymers such as isopropylidene resin.

  Furthermore, a polymer alloy or polymer blend composed of two or more polymers selected from the rubber, thermoplastic elastomer and thermoplastic resin can also be used.

  The resin, elastomer, copolymer, and the like used for the functional multi-layer tube are as described above, and a tube configuration having desired characteristics can be obtained by appropriately blending a conductive material or the like.

A known material can be used as the conductive material.
For example, it is as follows.
Carbon fine particles such as carbon black and graphite;
Fine metal particles such as nickel, silver, aluminum and copper;
Conductive metal oxide fine particles mainly composed of tin oxide, zinc oxide, titanium oxide, aluminum oxide and silica, and doped with impurity ions having different valences;
Conductive fibers such as carbon fibers;
Metal fibers such as stainless steel fibers;
Conductive whiskers such as conductive potassium titanate whiskers in which the surface of the carbon whisker or potassium titanate whisker is conductively treated with a metal oxide or carbon;
And conductive polymer fine particles such as polyaniline and polypyrrole;
Etc.

  The functional multi-layer tube used in the present embodiment is formed by extruding a conductive polymer composition comprising the above-mentioned various polymers, the above-mentioned conductive material, and other additives as required.

  Further, in order to obtain a film having a uniform thickness of each thin film layer of the tube to be formed and a more uniform dispersibility of the conductive material or the like, in this embodiment, a vertical tube extruder as shown in FIG. Is used.

  If the functional multi-layer tube used in the present embodiment is simply molded, it can be obtained by forming a film into a tube by an extrusion molding method, an injection molding method, a blow molding method or the like.

  For example, for the purpose of obtaining superior durability, environmental resistance, and the like, the seamless tube obtained by the above various molding methods can be further cross-linked to obtain a conductive cross-linked polymer.

  As a method for crosslinking the conductive polymer formed into a tube shape, a chemical crosslinking method or a radiation crosslinking method is effective by adding a crosslinking agent in advance according to the kind of the polymer.

  The chemical cross-linking method is a method of generating a cross-linking bond at a high temperature, and the radiation cross-linking method is a method of cross-linking by irradiating radiation such as an electron beam or γ-ray.

  Examples of the crosslinking agent include sulfur, organic peroxides and amines.

  Of the various crosslinking methods described above, the electron beam crosslinking method is preferable because there is no fear of contamination of the member to be charged due to the migration of the crosslinking agent or its decomposition product, and further, there is no need for high temperature treatment and safety.

The volume resistance value of the functional multi-layer tube used in the present embodiment is preferably 10 ⁴ to 10 ¹⁰ Ω · cm, and particularly preferably 10 ⁵ to 10 ⁹ Ω · cm.

  Further, in the present embodiment, the ultra-thin layered tubes appropriately function-separated are integrally formed at the same time, so that each layer is not made thicker than necessary. In addition, the flexibility of the foamed elastic layer can be effectively extracted in the overall configuration.

  The functional multi-layer tube used in this embodiment can be formed by various methods, but the extrusion method is suitable as described above.

  That is, a compound in which a polymer, a conductive material and, if necessary, a crosslinking agent, a stabilizer and other additives are mixed is produced.

  Then, a seamless tube can be continuously manufactured by extruding the compound from a nipple and a die forming a ring-shaped slit with an extruder and cooling (FIG. 2).

  A heat-shrinkable tube can be obtained if the tube diameter is expanded during cooling or after cooling and using a means such as air pressurization, and a non-heat-shrinkable tube can be obtained if no expansion treatment is performed.

  The functional multi-layer tube used in the present embodiment may be either non-heat-shrinkable or heat-shrinkable, but non-heat-shrinkable ones are employed in the examples.

  In the case of a non-heat-shrinkable tube, the inner diameter of the tube needs to be equal to or less than the outer diameter of the foamed elastic layer in order to ensure the adhesion between the foamed elastic layer and the functional multilayer tube.

  The external fitting process is completed by inserting a foamed elastic body layer having a core in a state where the tube diameter is expanded by blowing compressed air and releasing the air pressure.

  The present embodiment is a method for manufacturing a coated tube for a charging member, which includes a step of pushing a tube in the direction of gravity, an air cooling step, a water cooling sizing step, a tube take-off step, and a tube cutting step. In this method, a charging member is formed by coating an elastic body layer on the outer periphery of a core metal with a plurality of seamless tubes.

  Next, a vertical extrusion apparatus used in the present invention will be described with reference to FIG.

  The die 4 used for molding is provided with inner and outer double annular extrusion channels 6 and 7 around a central through hole 5 for introducing air.

  When molding, an inner layer elastomer is formed in the inner flow path 6 from the first extruder 8, and an outer layer is formed in the outer flow path 7 from the second extruder 9 in the functional multilayer tube. Each elastomer is injected under pressure.

  Thereafter, the inner layer 3 (i) and the outer layer 3 (o) are overlapped and integrated, extruded, and cooled by a water cooling ring 10 provided on the outer periphery of the functional multi-layer tube 3 obtained by air cooling.

  This is fed by a tube take-up device 21 and cut sequentially to a predetermined length by a cutting device 23 to cover a foamed elastic body layer having a cored bar 1 as a functional multi-layer tube for a charging roller in the next step.

  Reference numeral 24 is a mold, and 22 is a nipple.

  Here, the main points of the technology of the present embodiment will be described in more detail.

  FIG. 3 shows an apparatus diagram of a belt type (a) and a roll type (b) which are conventional take-up machines. FIG. 4 is a schematic diagram for explaining how to take out the tube by the chuck-type take-up means used in the present invention.

  4 includes two chuck mechanisms A and B that are moved up and down by the NC. First, the chuck mechanism A chucks the tube at the upper fixed position and pulls the tube downward at the set take-up speed.

  Next, the chuck mechanism B chucks the tube at the upper fixed position and starts to take out at the same speed as the chuck mechanism A. At the same time as the chuck mechanism B starts to be picked up, the chuck mechanism A unchucks the tube at the lower position and returns to the upper fixed position.

  At this time, the speed at which the chuck mechanism A returns to the upper fixed position is determined by the tube take-up speed and the required length of the tube.

  A and B are alternately repeated, and the tube is taken out. Such a chuck-type take-up device solves the problems of backlash and speed unevenness due to the shape accuracy of the take-up roll, which are problems in the roll-type take-up device.

  Furthermore, another point of the present embodiment is that the tube cutting step cuts the tube at the chuck positions of the chuck mechanism A and the chuck mechanism B.

  By cutting the chuck position, the portion affected by roundness and circumferential resistance unevenness by the chuck becomes a cutting portion.

  Since the tube in the vicinity of the cut portion is cut off after being covered and discarded, the portion used as a product does not touch the take-up device at all, and the straightness and the circumferential resistance unevenness are not changed before and after the take-off process.

  That is, the rate of change in roundness and resistance unevenness in the circumferential direction between the tubes before and after the take-off step is 1.1 or less, which was difficult to achieve with conventional means.

  Further, the problem of the roll type that causes the outer diameter unevenness in the longitudinal direction of the tube due to the vibration of the cutting process being transmitted to the tube before the water cooling sizing process is solved because the chuck system firmly chucks.

  Further, a better tube (0.3% or less) having a straightness Δ / Da × 100, which was difficult to achieve with conventional means, was obtained.

  Straightness Δ / Da × 100 is the total outer diameter measurement value of the difference Δ between the maximum value and the minimum value of the average value of the outer diameter at least at three locations in the circumferential direction at at least five outer diameter measurement positions in the tube longitudinal direction. The 100-percentage value (FIG. 5) with the average value Da is shown.

  FIG. 6 shows a schematic configuration of an electrophotographic apparatus having a process cartridge having a charging roller of the present invention.

  In FIG. 6, reference numeral 12 denotes an electrophotographic photosensitive member, which is rotationally driven in a direction indicated by an arrow at a predetermined peripheral speed, and receives a uniform charge of a predetermined positive or negative potential on its peripheral surface by the charging member 1 'during the rotation process. Next, exposure light 13 is received from exposure means (not shown) such as slit exposure or laser beam scanning exposure.

  Reference numeral 11 denotes a power source for the charging member 1 '. In this way, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor 12.

  The electrostatic latent image thus formed is then developed with toner by the developing means 14. Thereafter, the developed toner developed image is transferred from the sheet feeding unit (not shown) onto the transfer material 16 fed in synchronization with the rotation of the photoreceptor 12 between the photoreceptor 12 and the transfer unit 15. Are sequentially transferred.

  The transfer material 16 that has received the image transfer is separated from the photoreceptor surface, introduced into the fixing means 17, and subjected to image fixing, thereby being printed out as a copy (copy).

  The surface of the photoconductor 12 after the image transfer is cleaned by the cleaning means 18 after removal of the transfer residual toner, and is repeatedly used for image formation.

  In the present embodiment, a plurality of components such as the electrophotographic photosensitive member 12, the charging member 1 ', the developing unit 14, and the cleaning unit 18 are integrally combined as a process cartridge.

  The process cartridge can be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer.

  For example, the developing unit 14 and the cleaning unit 18 can be integrally supported together with the photosensitive member 12 and the charging member 1 ′ to form a cartridge, and the process cartridge 20 can be attached to and detached from the apparatus main body using the guide unit. As the guide means, the rail 19 of the apparatus main body can be used.

  Further, when the electrophotographic apparatus is a copying machine or a printer, the exposure light 13 reads the document from the reflected light or transmitted light from the document or a sensor and converts it into a signal.

  Thereafter, the light is emitted by scanning of the laser beam, driving of the LED array, driving of the liquid crystal shutter array, and the like performed according to this signal.

  More specifically, it demonstrates below with an Example and a comparative example.

“When the structure of a functional multi-layer tube is a resistance adjustment layer / conductivity control layer”
The resistance adjusting layer may be a resin whose material itself has an appropriate resistance value, or may be a resin whose resistance value is adjusted by mixing carbon.

  A multi-layered functional tube in which the material of each layer in this example is integrated by simultaneous extrusion can be formed. In the present invention, the tube is formed using a vertical extrusion device.

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

<Formation of foamed elastic layer>
A vulcanizing agent and a foaming agent are blended in ethylene-propylene-diene rubber (EPDM), and the resulting mixture is molded into a hose shape having an inner diameter of 4.5 mm and an outer diameter of 11.5 mm by an extrusion molding machine. The foamed elastic body layer foamed in the vulcanizing can was cut into a length of 225 mm, and the cored bar having a diameter of 5 mm and a length of 260 mm was inserted into the center hole.

<Formation of functional multi-layer tube>
As a material for the outer layer of the functional multi-layer tube, 100 parts by mass (61.3% by mass) of a styrene-based resin (styrene-ethylene / butylene-olefin copolymer resin, trade name: Dynalon, JSR, melting point 100 ° C.) ), 20 parts by mass of polyethylene (12.3% by mass), carbon black as trade name: Ketjen Black EC (manufactured by Lion Akzo), 12 parts by mass (7.4% by mass), and trade name: Special Black 250 (Degussa) 20 parts by mass (12.3% by mass), 10 parts by mass (6.1% by mass) of magnesium oxide, and 1 part by mass (0.6% by mass) of calcium stearate were mixed in a V-type blender for several minutes.

  This was further 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 materials for the inner layer, polyurethane elastomer (melting point: 120 ° C.) 100 parts by mass (76.3% by mass), carbon black (trade name: Ketjen Black EC) 20 parts by mass (15.3% by mass), magnesium oxide 10 parts by mass Parts (7.6% by mass) and 1 part by mass (0.8% by mass) of calcium stearate were pelletized in the same process as the material of the outer layer.

Example 1
Using a vertical extruder (special product manufactured by Plastic Giken Co., Ltd., see Fig. 2), the materials of these inner and outer layers are combined into a double layer with a single crosshead (temperature 150 ° C), and the appropriate temperature is obtained. Was extruded into cold water 10.

  After further cooling, the sample was taken up by a chuck type (FIG. 2 or FIG. 4) tube take-up device and cut into a tube length of 300 mm by a cutting machine.

  In addition, about 300 mm of the tube before the take-off process was also cut and collected with scissors.

  In this way, two functional multi-layer tubes having an outer diameter of about 12.0 mm, a film thickness of 500 μm, and a tube length of 300 mm before and after the take-up process were obtained.

(Comparative Example 1)
A functional multi-layer tube before and after the take-up step having an outer diameter of about 12.0 mm, a film thickness of 500 μm, and a tube length of 300 mm in the same manner as in Example 1 except that the roll type (FIG. 3B) was used as the tube take-up device. Two were obtained.

(Comparative Example 2)
A functional multi-layer tube before and after the take-up step having an outer diameter of about 12.0 mm, a film thickness of 500 μm, and a tube length of 300 mm in the same manner as in Example 1 except that a belt type (FIG. 3A) was used as the tube take-up device. Two were obtained.

  The roundness and circumferential resistance unevenness of the obtained functional multi-layer tube were measured.

Roundness measurement is performed at one measurement position in the longitudinal direction of the tube, the difference Δ ₀ between the maximum value and the minimum value of the outer diameter at eight locations in the tube circumferential direction, and the average value D ₀ of the measured outer diameter values at eight locations. And 100 percent value (Δ ₀ / D ₀ × 100).

  Further, the circumferential resistance unevenness measurement was represented by a ratio of DC current value max / DC current value min in one turn of the tube by passing the tube through a SUS rod having a diameter slightly smaller than the tube diameter.

From these, the change rate of the roundness and circumferential resistance unevenness of the tube _before and _{after the take-off process} ( _{after the} roundness _{take-up process} / _{before the} roundness _{take-off process} and _{after the} peripheral resistance unevenness _{take-off process} / _{before the} peripheral resistance unevenness _{take-off process} ) is obtained. It was.

  Furthermore, the straightness of the functional multi-layer tube obtained after the take-up process was measured.

  The tube is passed through a SUS rod having a diameter slightly smaller than the inner diameter of the tube, and the difference between the maximum value and the minimum value of the average value of the outer diameters at three locations in the circumferential direction while rotating at five outer diameter measurement positions in the tube longitudinal direction Δ The 100-percentage value (Δ / Da × 100) with the average value Da of all the outer diameter measurement values was obtained (FIG. 5).

<Production of charging roller>
The outer periphery of the foamed elastic layer was fitted into the functional multi-layer tube obtained by the above-described method after the take-up process by a tube coating apparatus (not shown) and pressed and adhered.

  An image was formed by using this charging roller for a primary charger of LBP (Laser Beam Printer; Laser Jet 2-P manufactured by Hewlett Packard). As a result, there is no gap between the functional multi-layer tube 3 and the foamed elastic body layer 2, no wrinkles on the functional multi-layer tube 3, and a good image without image unevenness is obtained. It was.

  As described above, image evaluation is also performed by an electrophotographic apparatus using the process cartridge in which the charging members of Example 1 and Comparative Examples 1 and 2 are incorporated. However, since Comparative Example 1 does not reach the image NG, it is Δ, better than that, and bad as ×.

  The present invention can be used for a cartridge for an electrophotographic apparatus or a charging member for an electrophotographic apparatus.

It is a longitudinal cross-sectional view of an example of the charging member as one Embodiment of this invention. It is a longitudinal cross-sectional view of an example of the vertical extruder of the covering tube for charging members used for one Embodiment of this invention. It is an apparatus figure of the conventional belt-type taking-up means and roll-type taking-up means used for one Embodiment of this invention. It is the schematic diagram explaining how to take out the tube by the chuck type take-up means used in one embodiment of the present invention. It is explanatory drawing of the measuring method of the outer diameter nonuniformity used for one Embodiment of this invention. 1 is a schematic configuration diagram of an electrophotographic apparatus having a process cartridge having a charging roller as one embodiment of the present invention.

Explanation of symbols

1 Core (metal layer)
1 'Charging member 2 Elastic foam layer 3 Functional multilayer film (functional multilayer)
3 (i) Inner layer 3 (o) Outer layer 4 Die 5 Center through hole 6 Extrusion channel 7 Extrusion channel 8 First extruder 9 Second extruder 10 Water-cooled ring 11 Power supply 12 Photoconductor 13 Exposure light 14 Development Means 15 Transfer means 16 Transfer material 17 Fixing means 18 Cleaning means 19 Rail 20 Process cartridge 21 Timing pulley (take-off process)
22 Nipple 23 Cutting process 24 Take-up belt (take-off process)
25 Chuck mechanism (A, B) (pickup process)

Claims (5)

Covering an elastic body layer on the outer periphery of the metal core with a plurality of seamless tubes, which includes a step of extruding the tube in a substantially gravity direction, an air cooling step, a water cooling sizing step, a tube take-off step, and a tube cutting step. In the manufacturing method of the charging member coated tube as the charging member,
In the tube take-up step, the tube is chucked at a fixed position in a higher position by one chuck mechanism of two chuck mechanisms that repeatedly move up and down alternately as means for attaching and detaching the tube, and the tube is moved downward at a set take-up speed. Taking over, and
The one-side chuck mechanism unchuckes the tube at the lower position and returns to the upper fixed position at an appropriate speed;
The other chuck mechanism chucks the tube at the upper fixed position at the timing of the unchuck and takes it at the set take-up speed;
The other chuck mechanism unchucking the tube at the lower position and returning to the upper fixed position at an arbitrary speed, and repeating the steps,
In the tube cutting step, the tube is cut at a chuck position of the chuck mechanism. In the covering tube for charging members manufactured by the manufacturing method of the covering tube for charging members according to claim 1,
Charging characterized in that the roundness of the tube and the rate of change in resistance unevenness in the circumferential direction before and after the tube take-up step are 1.1 or less and 0.3% or less in straightness Δ / Da × 100 Coated tube for members.
(Δ is the difference between the maximum value and the minimum value of at least three outer diameter average values in the circumferential direction at the five outer diameter measurement positions in the longitudinal direction of the tube Da is the average value of all outer diameter measurement values) A charging member, wherein the charging member used as a charging means of an electrophotographic apparatus is produced by coating the covering tube for a charging member according to claim 2 on an elastic body layer on an outer periphery of a cored bar. An electrophotographic apparatus cartridge comprising the charging member according to claim 3, wherein the electrophotographic apparatus cartridge is detachable from the electrophotographic apparatus. An electrophotographic apparatus comprising the cartridge for an electrophotographic apparatus according to claim 4.