JPH11123772A - Device for manufacture of coating tube for charging member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an irregular thickness amount to a low value without damaging a surface of a tube to be molded by effectively avoiding a generation of a deflection caused by the fact that a gravity is orthogonal to a flowing direction of the tube by disposing an element structure necessary for molding the tube in a longitudinal direction. SOLUTION: A tube T obtained by extruding a pellet introduced into a material supply port of an extruder or the like assembled in a vertical type from a small-diameter thin die 1 to mold it is lowered at its temperature by several deg.C in an air atmosphere 3 before entering into a sizing tube 6 connected to a water tank 2. An excess force to be applied to a surface of the like of the tube at this stage disturbs a precise seamless tube formation. For example, if supply water is fed in the tank 2 with high energy, its water surface is rippled and hence it affects an influence to a surface state of the tube T of still hot and flexible state. Then, a shielding plate 5 is provided at a tube outlet 4 of the supply water to suppress the rippling so that the supply water is sequentially spread to the surface of the tube T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless covering tube used in a charging member for charging an object to be charged by applying a voltage to the object to be charged in an electrophotographic apparatus. And an apparatus for manufacturing the same.

[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. The contact charging method is a method in which a charged object is charged to a predetermined polarity and potential by applying a voltage to a charging member arranged in contact with the charged object, and has an advantage that a voltage of a power supply can be reduced. Have. In addition, there are advantages that the generation of corona products such as ozone can be reduced, the structure is simple, and the cost can be reduced.

As a voltage applied to the charging member, there is also a method of applying only a DC voltage (DC application method). However, the DC voltage 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. A method of forming an oscillating electric field having a peak-to-peak voltage (an electric field whose voltage value changes periodically with time) between a contact charging member and a member to be charged and charging the surface of the member to be charged (AC application method) It is possible to charge more uniformly, and it is more desirable.

[0004] Such a contact charging device is disclosed in Japanese Patent Application Laid-Open Nos. 63-7380 and 56-91253, based on the shape and form of a charging member to be brought into contact with a member to be charged. Publication, etc.) and a blade type charger (JP-A-64
No. 24264 and No. 56-194349), and a brush-type charger using a brush-shaped member (charging brush) (Japanese Patent Application Laid-Open No. 64-26464).

The roller-shaped charging member is rotatably supported by a bearing, is pressed against the member to be charged at a predetermined pressure, and is configured to rotate following the movement of the member to be charged, and is usually provided at the center as a base. A multilayer structure having a shaft, a conductive elastic layer provided in a roller shape around the shaft, and a surface layer provided on the outer periphery of the shaft.

[0006] Among the above layers, the shaft is a rigid body for maintaining the shape of the roller, and also has a role as a power supply electrode layer.

The elastic layer usually has a thickness of 10 ⁴ to 10 ⁹ Ω ·
Since a function of ensuring uniform contact with the member to be charged is required by having a volume specific resistance of 1.0 cm and elastically deforming, the rubber hardness (JIS A) provided with conductivity is usually 70 degrees. Vulcanized rubber having the following flexibility is used.

[0008] Conventional roller-shaped charging members are classified into a foam type using a rubber foam (or sponge-like rubber) as an elastic layer and a solid type using no rubber foam. Also, the surface layer improves the charging uniformity of the member to be charged,
A function to prevent the occurrence of leaks due to pinholes on the surface of the member to be charged and to prevent the toner particles and paper powder from adhering, as well as oils and plasticizers used to reduce the hardness of the elastic layer. It also has a function of preventing bleeding of the softener. The volume resistivity of the surface layer is
Usually, it is 10 ⁵ to 10 ¹³ Ω · cm, and conventionally, it is formed by applying a conductive paint or covering a seamless coating tube.

As a method of manufacturing such a coated roller covered with a tube, there are a method using a heat-shrinkable tube and a method using a non-shrinkable tube. When using a heat-shrinkable tube, insert a shaft or an elastic roller with an elastic body formed on the shaft into a heat-shrinkable tube with a primer applied on the inner surface, and heat the entire tube to shrink the tube to form a roller outer periphery. In close contact. When using a non-shrinkable tube, place the non-shrinkable tube on the inner wall of the cylindrical mold while pulling in the longitudinal direction,
The pressure between the tube and the inner wall of the cylindrical mold is reduced to bring the tube into close contact with the inner wall, an elastic roller having an elastic body formed on a shaft is inserted, and then heated and fused to coat the outer periphery of the roller with the tube.

However, when a heat-shrinkable tube is used, the manufacturing process is simple, but the manufacture of the heat-shrinkable tube is difficult, uneven thickness is inevitable, and it is expensive. In addition, it is difficult to adjust the shrinkage ratio, and there is a problem that wrinkles are generated.

On the other hand, when the surface layer is formed of a seamless covered tube, problems such as pinholes can be avoided and the control of the film thickness is relatively easy. Then, by performing the outer fitting process one by one, a plurality of resistance layers can be sequentially overlapped to obtain a roller having a desired resistance value.

[0012]

Conventionally, in a device for manufacturing a seamless coated tube used for such a purpose, the flow of a molded product is developed in a horizontal direction due to the arrangement of the device and the design of the process. Often. Molded products are
Due to the flow in the horizontal direction, the distribution in the direction of gravity, that is, the effect of gravity acting in the circumferential direction, inevitably affects each stage of the process. That is, since the tube extruded from the die bends in the direction of gravity, the tube must be supported at various places. These support members touch the still hot tube surface and cause damage to the tube surface. Immediately after being extruded from the die, the material is at a temperature close to the melting temperature and is greatly affected by gravity. At this time, since the extrusion port of the die is oriented in the horizontal direction, the wall thickness distribution of the tube in which it is difficult to adjust the wall thickness is even more difficult.

In order to apply a tube, in particular, a small-diameter, thin-walled tube with small uneven thickness to an electrophotographic charging member that requires uniformity and precision, the above-described conventional apparatus configuration is fundamental. The problem is inherent.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a means for arranging each element of a tube forming means in the direction of gravity, that is, a vertical direction, and forming a desired tube. And, furthermore,
An object of the present invention is to incorporate the formed tube as a component of a charging member and use it for an electrophotographic apparatus.

[0015]

According to the present invention, there is provided an apparatus for manufacturing a coated tube for forming a charging member by coating a plurality of layers of a seamless coated tube on an elastic body. A material for forming the coated tube is a small-diameter thin-walled die having a diameter of 30 mm or less, which is extruded into a tube shape, and sequentially arranged below in the gravity direction of the die, an air cooling unit for cooling the tube, a water cooling sizing unit, It is characterized by comprising a take-up means for taking the tube and a cutting means for cutting the tube to a predetermined length.

That is, the present invention converts the influence of gravity into a problem-free direction, which cannot be eliminated by the conventional means for forming a small-diameter seamless tube by the method of manufacturing a coated tube, and utilizes gravity instead. Provided is a means for forming a small-diameter seamless tube applicable to the production of a charging member for electrophotography requiring uniformity and precision.

Further, the cooling water supply amount in the water cooling sizing means is 50 g / min to 6000 g / min,
Preferably, it is 50 g / min to 2500 g / min, and its water temperature is controlled at about 30 ° C.
The tube withdrawal speed by the tube withdrawal means and the tube weight per unit time calculated from the tube shape and the density are smaller than the weight of the tube material extruded from the die, and the difference is relative to the weight of the die extruded material. This is an apparatus for manufacturing a coated tube for a charging member designed to have a ratio of 10% to 30%.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The steps performed in the coated tube manufacturing apparatus of the present invention will be described below with reference to the drawings.

First, the material used for tube forming is pelletized. As a material on the surface layer side, here, 100 parts by weight of a styrene-based resin (styrene-ethylene / butylene-olefin copolymer resin) is mainly used, and 18 parts by weight of polyethylene and carbon black (trade name “Ketjen Black EC”) , Lion Akzo Co., Ltd.) 16 parts by weight were mixed in a V-type blender for several minutes, and the mixture was further melt-kneaded at 190 ° C. for 10 minutes using a pressurized kneader, cooled, pulverized by a pulverizer, and extruded by a single screw extruder. Use the pelletized one.

The pellets are put into a material supply port of a melt extruder, such as an extruder, assembled at a height of about a two-story building, and extruded into a tube. The tube extruded from the die is about twice the size of the desired outer diameter and inner diameter, but it is properly stretched by its own weight and the pulling force of tube take-up, and its diameter becomes smaller, and the water cooling sizing in the next process It is adjusted to a desired inner diameter and outer diameter. During this time, adjustment of uneven thickness and the like are also performed.

However, in the case of the conventional horizontal apparatus, gravity is applied in a direction perpendicular to the flow of the tube, so that the apparatus naturally bends. Deflection means that in the flow direction,
This means that there are portions that extend and portions that do not, and it is difficult to say that the portions are uniform in characteristics.

FIG. 1 shows an embodiment of the coated tube manufacturing apparatus of the present invention.

In FIG. 1, the above-mentioned pellets are
The tube T formed by being extruded from the small-diameter thin-wall die 1 mm or less passes through the air atmosphere section 3 before entering the sizing pipe 6 connected to the shallow water tank 2. In the air atmosphere 3, a temperature drop of several degrees Celsius is observed. In this case, providing a mechanism for supplying and discharging air so as to generate an appropriate air circulation is effective for obtaining a more precise sizing effect. Appropriate conditions can be easily found by experimenting with various changes in specific heat, temperature, supply amount, discharge amount, and the like of air.

The water-cooled sizing means is an important step for setting the final dimensions. On the other hand, the cooling in the air atmosphere part 3 is auxiliary, and at this stage, the temperature of the tube T is still several degrees lower than the temperature immediately after extrusion.
At a low level, the application of an extra force to the tube surface or the like at this stage hinders the formation of a precise seamless tube targeted by the present invention. For example, when the supply water flows in the water tank 2 vigorously, the water surface undulates and affects the surface condition of the still hot and flexible tube T.

For example, if the wave height fluctuates greatly,
The length of the tube surface in contact with water is different, and cooling and solidification has already progressed in the high water area, but on the other hand, in the low wave height area, it is still hot, so the weight acting on the tube is The pulling force due to pulling is easily affected by the wave's own weight and pulling. Therefore, it is considered that this also affects the delicate change in thickness and the orientation of the dispersed fine particles in the tube material.

In view of the above, the pipe outlet 4 in the water cooling sizing means of the supply water is provided with a shield plate 5 so as to suppress waving. Of course, it is needless to say that the configuration is such that the supply water is sequentially distributed to the surface of the tube T.

In connection with the detailed structure of the actual sizing pipe 6, it is desirable to design the distance between the supply water pipe outlet 4 and the sizing pipe 6 appropriately. In other words, the water tank 2 has a shallow structure in the vicinity of the supply water pipe outlet 4, and forms a tapered portion 7 having a deeper center in the central portion continuous therewith. It has a prescribed structure.

[0028] Since the tapered portion 7 is provided as described above, even if a ripple occurs at the pipe outlet 4 of the supply water, the wave height decreases at a portion where the water depth becomes deep.

Further, the structure of the tapered portion 7 is such that water warmed by the first heat exchange with the tube T on the surface of the water tank 2 flows in the overflow direction (partly flows down together with the tube T passing through the sizing tube 6). However, in other parts, due to the deviation of the water temperature due to the fact that the supply water temperature is still at the initial temperature, it is considered that convection of water occurs inside the water tank 2. Due to this convection, the supply water flows along the inner surface of the tapered portion 7, and further forms a water film on the tube T passing through the sizing tube 6, and at the same time, through the sizing tube 6 designed to a predetermined size. Run down.

Therefore, heat exchange in the central sizing pipe 6 is performed between the supply water at a predetermined temperature and the tube T. Appropriate conditions include factors (specific heat, weight, film thickness, diameter, etc.) determined by the material and dimensions of the tube T, the speed at which the tube T passes through the sizing tube 6 (related to the take-up speed described later), and the amount of supplied water It is almost decided by.

On the other hand, in the case of the conventional horizontal (horizontal) arrangement, since there is bending in the direction of gravity, the uniformity of the film of the cooling supply water as in the case of the vertical arrangement shown in FIG. Can't expect. Further, since the tube only moves in the horizontal direction in the water tank, the effect of regulating the original outer diameter and adjusting the diameter cannot be expected. A sizing means such as a PVC pipe, which regulates the diameter while rubbing the surface, is not suitable for forming a coated tube used for a charging member for electrophotography. Since the coating tube for the charging member for the electrophotographic apparatus is used as a component of a fine image forming means, the scratch on the surface and the influence on the inner surface of the tube when the scratch is formed cannot be ignored.

In the present invention, depending on the tube material and the molding size, for example, under the condition that the temperature of the supply water for cooling is about 30 ° C. and the take-off speed of the tube is about 5 m / min, the amount of supply water is preferably 50 g / min. ~ 6
000 g / min, more preferably 50 g / min
Ｇ2500 g / min.

With the amount of water under such conditions, the water temperature can be kept within an appropriate range while the tube temperature is lowered to a predetermined temperature.

In addition to the water-cooling sizing by the above-mentioned water-cooling sizing means, a cold-water shower means 8 can be provided downstream of the water-cooling sizing means as an effective means for fixing the sizing dimensions. When the cold water shower means 8 is used in combination, the sizing effect is more reliable. In this case, too, the cold water hits the surface of the tube moving in the direction of gravity, forming a water film along the tube and flowing down, so the force to bend the tube in the direction perpendicular to the tube flow direction is ignored. it can.

The next step is a step of picking up the sized tube at an appropriate speed to prevent the tube from stagnating in the previous step. To perform this step, a tube pick-up means 9 is provided. It is composed of a pulley 10 and a feed belt 11. The tube T is extruded at a speed determined by the size of the die and the mandrel and the extrusion amount (speed) of the tube material, and moves to the next step, so that no bending occurs and conversely, excessive tension is applied. It is necessary to move the tube at an appropriate speed so that it does not catch. The amount of tubing within a unit length of travel varies during travel through the system, as the take-off speed is adjusted to give a tube of a defined final shape and dimensions. That is, at the stage immediately after extrusion, the tube has a diameter approximately twice as large as its final dimension, but is close to the melting temperature of the material and is in an easily stretched state. The amount of tubing within the unit length of travel is, of course, greater in the region immediately after extrusion, depending on the particulars. The difference in the amount of the material is set within an appropriate range in a coated tube aiming at a small diameter and a thin wall.

In the present invention, the tube pulling speed by the tube pulling means 9, the shape of the tube T,
The weight of the take-off tube per unit length determined from the density is smaller than the weight of the tube material extruded from the die, and the ratio of the difference to the weight of the die extruded material is preferably 10% to 30%. A coated tube having a desired thickness and a uniform thickness can be obtained.

The next step of the picking-up step is a step of cutting the tube to a length obtained by adding a margin length to the designed length, and storing the tube on a table for transferring to the final cutting step without damaging the surface. . Accordingly, automation of the table structure and its moving means is naturally a factor to be considered in practicing the present invention.

The extra length of the tube means that the covering tube is put on a roller in which an elastic body is previously provided concentrically on the shaft,
This is the length provided for the work process of cutting off the surplus. Needless to say, the final cutting step is also a cutting means that takes into account the “surface damage” noted in each of the above steps.

Here, using the manufacturing apparatus of the present invention, FIG.
The material constituting the charging member having the structure shown in FIG.

In FIG. 2, the charging member 15 in the form of a conductive roller is made of stainless steel, plated iron,
An elastic layer 12 made of a conductive elastic material is provided on the outer peripheral surface of a shaft 14 made of a good conductive material such as brass or conductive plastic, and a tubular multilayer film is further formed on the outer peripheral surface of the elastic layer 12. In order to form the multilayer film 13, a coated tube manufactured by using the above-described manufacturing apparatus is used.

Here, as the conductive elastic material constituting the elastic layer 12, a conductive rubber composition containing a conductive material or a conductive polyurethane foam can be used.

The rubber component constituting the foamed conductive rubber composition is not particularly limited, but ethylene propylene rubber (EPDM), chloroprene, chlorosulfonated polyethylene mixed with a conductive material, epichlorohydrin and ethylene A foam of an oxide copolymer rubber or a foam of a copolymer rubber of epichlorohydrin and ethylene oxide mixed with a conductive material can be suitably used.

As the conductive material to be incorporated into these rubber compositions, known materials can be used, for example, fine carbon particles such as carbon black and graphite; fine metal particles such as nickel, silver, aluminum and copper; tin oxide and zinc oxide , Titanium oxide, aluminum oxide, silica, etc. as main components, conductive metal oxide fine particles doped with impurity ions having different valences; conductive fibers such as carbon fibers; metal fibers such as stainless steel fibers; Examples include conductive whiskers such as conductive potassium titanate whiskers obtained by subjecting the surface of potassium titanate whiskers to conductive treatment with metal oxide or carbon; and conductive polymer fine particles such as polyaniline and polypyrrole. The compounding amount can be 3 to 100 parts by weight, particularly 5 to 50 parts by weight, based on 100 parts by weight of the total rubber component, whereby the volume resistance of the elastic layer is 10 ¹ to 10.
It is preferable to adjust to about ⁹ Ωcm. The elastic layer can be formed by a known vulcanization molding method, and its thickness is appropriately set according to the use of the roller and the like, but is usually 1 to 20 mm.

The charging member 15 is provided with a multilayer film 13 formed by coating a multilayer coating tube on the elastic layer 12. The thermoplastic resin constituting the multilayer film 13 may be any thermoplastic resin that can be extruded. Specifically, ethylene propylene rubber (EPDM), ethylene vinyl acetate, ethylene ethyl acrylate, Polyamide such as ethylene methyl acrylate, styrene butadiene rubber, polyester, polyurethane, nylon 6, nylon 66, nylon 11, nylon 12, and other copolymerized nylon, styrene ethylene butyl, ethylene butyl, nitrile butadiene rubber, chlorosulfonated polyethylene, Ordinary rubber such as polysulfide rubber and chlorinated polyethylene, chloroprene rubber, butadiene rubber, 1,2-polybutadiene, isoprene rubber, polynorbornene rubber, or styrene-butadiene-styrene (SBS), styrene Down - butadiene - styrene hydrogenated product can be used thermoplastic rubber (SEBS), etc., it is not particularly limited.

Alternatively, elastomers such as the above-mentioned resins and copolymers and modified elastomers, and polyethylene, polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT)
Saturated polyester, polyether, polyamide, etc.
Polycarbonate, polyacetal, acrylonitrile butadiene styrene, polystyrene, high impact polystyrene (HIPS), polyurethane, polyphenylene oxide, polyvinyl acetate, polyvinylidene fluoride, polytetrafluoroethylene, polystyrene acrylonitrile-butadiene-styrene resin (ABS) and acrylonitrile-ethylene / Styrene-based resins and acrylic resins such as propylene rubber-styrene resin (AES), acrylonitrile-allylic rubber-styrene resin (AAS), vinyl chloride resin, vinylidene chloride resin,
It is preferable to use a combination of each resin and a material made of a copolymer. Further, a polymer alloy or a polymer blend comprising two or more polymers selected from the above rubber, thermoplastic elastomer and thermoplastic resin can also be used.

As a material for forming the shaft 14, for example, a good conductor such as aluminum, copper, iron, or an alloy containing these is preferably used. Local unevenness of the resistance value of the elastic layer 12 which is a problem in the related art can prevent poor charging caused by uneven charging. The metal layer used in the present invention may be a metal tube having a thickness of 0.1 to 1.5 mm or a rod shape.

The multilayer film 13 is formed into a conductive cross-linked polymer by further cross-linking the coated tube manufactured by the apparatus of the present invention in order to obtain, for example, better durability and environmental resistance. You can also. As a method of cross-linking the conductive polymer formed into 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 the cross-linking is performed at a high temperature. An effective method is a chemical cross-linking method for forming the film, or a radiation cross-linking method for cross-linking by irradiation with radiation such as an electron beam or γ-ray. Among the above various cross-linking methods, the electron beam cross-linking method has no danger of contamination of the charged member due to migration of a cross-linking agent or a decomposition product thereof, furthermore, there is no need for high-temperature treatment, and particularly in terms of safety. preferable.

FIG. 3 shows a schematic configuration of an electrophotographic apparatus incorporating the roller-shaped charging member 15 having the multilayer film formed as described above.

In FIG. 3, reference numeral 16 denotes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum), which is driven to rotate at a predetermined peripheral speed in the direction of an arrow. The photosensitive drum 16
In the rotation process, the peripheral surface thereof is uniformly charged at a predetermined positive or negative potential by the charging member 15, and then receives image exposure light 18 from an image exposure means (not shown) such as slit exposure or laser beam scanning exposure. . Thus, an electrostatic latent image is sequentially formed on the peripheral surface of the photosensitive drum 16.

The formed electrostatic latent image is then transferred to developing means 1
9, the developed toner image is transferred from a paper supply unit (not shown) to the transfer material 21 fed between the photosensitive drum 16 and the transfer means 20 in synchronization with the rotation of the photosensitive drum 16. Are sequentially transferred by the transfer means 20.

The transfer material 21 having undergone the image transfer is separated from the photoreceptor surface, introduced into the image fixing means, and subjected to image fixing, thereby being printed out of the apparatus as a copy.

The surface of the photosensitive drum 16 after the transfer of the image is cleaned by the cleaning unit 22 to remove the untransferred toner, and is used repeatedly for image formation.

A plurality of components such as the photosensitive drum 16, the charging member 15, the developing means 19, and the cleaning means 22 are integrally connected as a process cartridge. It may be configured to be detachable from the main body of an electrophotographic apparatus such as a beam printer. For example, the developing unit 19 and the cleaning unit 22 are integrally supported together with the photosensitive drum 16 and the charging member 15 to form a cartridge, and a process cartridge that can be attached to and detached from the apparatus main body by using a guide unit such as a rail of the apparatus main body. it can.

When the electrophotographic apparatus is a copying machine or a printer, the image exposure light 18 is read or transmitted light from the original, or the original is read by a sensor and converted into a signal. This is light emitted by scanning of a laser beam, driving of an LED array, driving of a liquid crystal shutter array, and the like.

The above-described 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 as an electrophotographic apparatus incorporating the same.

[0056]

Embodiments of the present invention will be described below.

(Example 1) <Formation of Surface Tube> As a material of the coated tube to be a surface layer, a styrene resin (styrene-ethylene / butylene-olefin copolymer resin, trade name “Dinalon”,
100 parts by weight of Japan Synthetic Rubber Co., Ltd.), 18 parts by weight of polyethylene and carbon black (trade name “Ketjen Black EC”, manufactured by Lion Akzo Co., Ltd.) 16
The parts by weight were mixed in a V-blender for several minutes. This was further melt-kneaded at 190 ° C. for 10 minutes using a pressure kneader. After further cooling, the mixture was pulverized by a pulverizer and pelletized by a single screw extruder.

The above-mentioned pellets are extruded into a tube using a vertical extruder equipped with a die 1 having the structure shown in FIG. 1 and sequentially passed through an air-filled portion of about 5 cm length into a water tank 2 and a sizing pipe 6. Let it through. Cooling water (about 2300 g / min) adjusted to about 30 ° C. is supplied to the water tank 2. After cooling water is suppressed by the shielding plate 5 at the pipe outlet 4, the cooling water is tapered toward the center with the shallow water tank 2.
Through the sizing pipe 6 that has become deeper, it partially falls down. Here, cooling, dimensional adjustment, and the like are performed. In addition, samples prepared under the conditions of a water amount of about 50 g / min, about 2500 g / min, and about 5500 g / min were also evaluated.

Further, the tube T is drawn through the cold water shower section 8 having the above water temperature. The take-up speed of the tube T is roughly calculated and adjusted from the amount of extrusion from the die 1 and the molding size of the tube T. Next, it is cut to a length with a margin for the coating length, and stored on a pedestal (not shown) so as not to contact with each other.

Thus, the outer diameter is about 11 mm and the thickness is 25
A 0 μm surface layer tube was obtained.

(Formation of Middle Layer Tube) A polyurethane elastomer 100
Parts by weight, 17 parts by weight of carbon black (trade name "Ketjen Black EC"), 10 parts by weight of magnesium oxide,
1 part by weight of calcium stearate was pelletized in the same process as the material on the surface layer side.

The above pellets are extruded into a tube using the vertical extruder shown in FIG. 1 and passed through a water tank 2 and a sizing pipe 6 through an air-filled portion having a length of about 5 cm. Cooling water adjusted to about 30 ° C. (about 2300
g / min). Cooling water is supplied to the pipe outlet 4
After the momentum of the water is suppressed by the shielding plate 5 of the shallow water tank 2,
It flows down partly through the sizing pipe 6 that tapers deeper toward the center. Here, cooling, dimensional adjustment, and the like are performed. The amount of water was about 50 g / min, about 2
Samples prepared under the conditions of around 500 g / min and around 5500 g / min are also evaluated.

Further, the tube T is taken through the cold water shower section 8 having the above water temperature. The take-up speed of the tube T is roughly calculated and adjusted from the amount of extrusion from the die 1 and the molding size of the tube T. Next, it is cut to a length with a margin for the coating length, and stored on a pedestal (not shown) so as not to contact with each other.

As described above, the outer diameter is about 11 mm,
An m-thick middle layer tube was obtained.

(Formation of Foamed Elastic Material Layer)
A hose-shaped foamed elastic layer 12 having an outer diameter of 11.5 mm (EP
DM rubber, a vulcanizing agent and a foaming agent are blended, and the mixture is molded into a hose shape by an extruder and foamed in a vulcanizing can), cut into a length of 225 mm, and the center hole is
A shaft 14 having a length of 260 mm and a diameter of 5 mm was inserted.

The middle tube (thickness: about 400 μm) cut into a length of 228 mm was covered with a tube covering device (not shown), and pressed tightly with the foamed elastic body.

Next, the above-mentioned surface tube (thickness: about 250 μm) cut into a length of 230 mm by a tube coating device (not shown) by reversing the shaft arrangement at the time of coating the surface layer was placed on the middle layer tube. To form the final shape.

This charging member was replaced with a charging member of LBP (laser beam printer; Laser Jet 2-P manufactured by Hewlett-Packard Co.), and an image was formed using this. As a result, the adhesion between the middle tube and the surface tube and between the middle tube and the foamed elastic body 12 could be ensured, and the formed image was good.

The electric resistance of the charging member was measured by the following method. That is, as shown in FIG. 4, an aluminum foil (or copper thin plate) 23 having a width of 10 mm is formed on the charging member 15.
, And 250 V DC was applied from the power supply 24 between the shaft 14 and the aluminum foil 23, the current flowing at that time was measured, and the resistance value between the shaft 14 and the aluminum foil 23 was calculated. Then, by moving the position of the aluminum foil 23, a local variation of the resistance value of the charging member 15 in the longitudinal direction was measured. The local resistance value of the charging member 15 measured in this way was 0.6 to 0.9 MΩ, and it was found that the uniformity was extremely high.

Further, the lines, irregularities, wrinkles and the like on the surface of the charging member 15 were visually observed, but no problematic portions were found.

Next, the charging member 15 is mounted on a cartridge (EP-L, manufactured by Canon Inc.), and the cartridge is mounted on a laser beam printer (Las, manufactured by Canon Inc., Las).
erShotA404) to perform durability and visually evaluate the image quality of the output image. As a result, 25 ° C, 5
Even when 3500 images were output in an environment of 0% RH, no abnormality was observed.

Example 2 In Example 1, the extrusion rate of the surface layer material was 52 g / min, and the extrusion rate of the intermediate layer material was 97.
The weight of the surface layer tube obtained from the take-up speed was 42.08 g / min, and the weight of the middle layer tube was 79.6 g / min with respect to g / min. Therefore, the surface tube is 19.1% and the middle tube is 19.1%.
This is a condition corresponding to 7.9%.

Samples were prepared and evaluated under the conditions of about 10% and about 30%.

(Experimental Example 1) The steps up to the formation of the foamed elastic material layer are the same as those in Example 1, but when forming the surface layer tube and the intermediate layer tube, the supply amount of the cooling water is extremely small and extremely small. A comparison was made with the case where there were many. A few examples are 3
0 g / min, and 6500 g / min in many cases.

<Comparative Evaluation> In the comparative evaluation of Example 1 and Experimental Example 1, 30 g when the supply amount of cooling water was extremely small
In the case of / min, the amount of water does not fill the narrow gap of the sizing 6 and the tube is clogged at the upper part of the sizing 6. It is considered that this is because the cooling water covers the tube and plays a role of a lubricating liquid to pass the tube through the sizing tube 6 of the water-cooling sizing means. .

On the other hand, the supply amount of the cooling water is extremely large.
In the example of 500 g / min, although the pipe outlet of the supply water is covered with the shielding plate, the water surface of the water tank 2 of the water cooling sizing means, which should be calm, is rippled. Since a tensile force is applied in the direction of gravity, a temporal shift at the time of entry into the water surface is a slight shift in stretching, and a horizontal sway occurs, thereby impairing the characteristics originally required. further,
The structure is such that the water overflows from the end of the shallow water tank 2. However, since the amount of water is large, a countermeasure for excessive overflow was required for the original structure.

In the case of the cooling water supply rate of about 50 g / min applied in Example 1, the tube take-up speed is slow or
Alternatively, when the tube moves sideways, the water film in the extremely narrow gap between the tube outer diameter and the sizing tube inner diameter is more likely to be broken than in the case where the supply amount is larger than this condition, but the tube outer diameter is 11.6 mm. Pipe inner diameter 11.0m
The formation of the water film can be adjusted from m and the take-up speed.

In the case of supplying about 5500 g / min of cooling water, a means for shutting off the supply water at the pipe outlet 4 is properly required. In the present invention, the shielding plate 5 is a cylinder that is larger than the diameter of the water pipe that covers the pipe outlet 4 while being closed. This shielding plate 5
Can be appropriately selected depending on the amount of cooling water and the degree of undulation on the surface of the water tank.

(Experimental example 2) The formation up to the foamed elastic material layer
Same as Example 2, except that when forming the surface layer tube and the middle layer tube, the tube pulling speed by the tube pulling means and the tube weight per unit time calculated from the tube shape and the density are the tubes extruded from the die. Samples were prepared and evaluated using experimental examples of 5% and 40% of the ratio of the difference to the die extrusion material weight, which is smaller than the weight of the material.

In the comparative evaluation between Example 2 and Experimental Example 2, in the case of 5%, which is an example of the lower region of the preferred range, the die diameter is smaller than about twice the desired tube diameter, and immediately after extrusion. The tube does not need to be pulled so strongly. However, originally, the uneven thickness immediately after extrusion is to be reduced in the taking-out process, and the stretching here, the uneven thickness adjusting action does not work significantly, so that the uneven thickness is smaller than that in which the ratio is within a desired range. There was a big trend.

40% which is an example of the upper region of the preferred range
Is the case where the die diameter is larger than about twice the desired tube diameter. Since the thickness of the tube in the mid-molten state immediately after extrusion is thick, this is adjusted to the tube outer diameter and inner diameter of the design dimensions within a relatively short distance,
The local temperature distribution, the uniformity of the take-up speed, and the vibration applied to the tube have a subtle effect.

The cause of this local temperature distribution is the air environment in contact with the tube immediately after extrusion, and the way in which the air hits and the amount of circulation must be taken into consideration. Can be found by experiment. Experimentally, for example, it has been confirmed that the tube temperature immediately after extrusion at 200 ° C. is lowered by 3 to 6 ° C. before going to the sizing tube in the next step.

When the take-off speed is lacking in uniformity, in an extreme case, the cooling stops and a little progresses, so that the situation is different from the state of the tube at the portion where the take-up was performed smoothly.

The presence / absence of vibration also has a subtle effect on the tube to be formed, because it is a condition deviating from uniformity for the above-mentioned reason.

As described above, even when the weight of the tube to be taken out per unit length is smaller than the weight of the tube material extruded from the die, and the ratio of the difference to the weight of the die extruded material exceeds a desired range. Although the effect of adjusting the thickness deviation can be expected, other obstruction conditions are newly considered. Actually, there is a variation, but there is a possibility that a defect on a molded article considered to be caused by these may occur.

Although the local resistance values of the charging members 15 are measured and compared, they fall within the range of the resistance values described above.

The unevenness (roughness) on the surface of the charging member 15 is
No problem was observed in each of the examples and experimental examples. If it dares to say, in the case of the example where the extrusion amount immediately after the tube extrusion in the case of the experimental example 2 is large, it seems that there is a wavy part other than the normal roughness.

A plurality of components such as the photosensitive drum 16, the charging member 15, the developing means 19, and the cleaning means 22 are integrally connected as a process cartridge. It may be configured to be detachable from the main body of an electrophotographic apparatus such as a beam printer. For example, the developing means and the cleaning means 22 are integrally supported together with the photosensitive drum 16 and the charging member 15 to form a cartridge,
A process cartridge that can be attached to and detached from the apparatus main body by using guide means such as an apparatus-oriented rail can be provided.

The charging members 15 under the various conditions of Examples 1 and 2 and Experimental Examples 1 and 2 were incorporated into a process cartridge and image evaluation was performed.
Some problems were found on the images, but they were not serious problems in practical use.

[0090]

As described above, according to the present invention, in the case of the conventional horizontal arrangement, it cannot be avoided.
The occurrence of deflection due to gravity being in a direction perpendicular to the direction in which the tube flows is reliably avoided by arranging the element structures required for tube forming in the vertical direction, whereby the surface of the formed tube is reduced. There is no flaw and the amount of uneven thickness can be kept low. The charging member obtained by coating the thus formed tube with a shaft having an elastic body exhibits extremely high performance when incorporated in an electrophotographic apparatus.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a coated tube manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a roller-shaped charging member covered with a covering tube manufactured by the apparatus of the present invention.

FIG. 3 is a schematic longitudinal sectional view of an electrophotographic apparatus to which the charging member of FIG. 2 is applied.

FIG. 4 is an explanatory view showing a method for measuring a resistance value of a charging member.

[Explanation of symbols]

 T tube 1 dice 2 water tank 3 air atmosphere section 4 pipe outlet 5 shielding plate 6 sizing pipe 7 sizing introduction section 8 cold water shower means 9 tube take-up means 10 timing pulley 11 feed belt 12 elastic layer 13 multilayer film 14 shaft 15 charging member Reference Signs List 16 photosensitive drum 17 power supply 18 exposure light 19 developing means 20 transfer means 21 transfer material 22 cleaning means 23 aluminum foil 24 power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Yamashita 1888-2 Kusazaki, Kukizaki-cho, Inashiki-gun, Ibaraki Prefecture Within Canon Chemical Co., Ltd. (72) Inventor Hiroshi Koyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] An apparatus for manufacturing a coated tube for forming a charging member by coating a plurality of layers of a seamless coated tube on an elastic body, wherein a material for forming the coated tube is extruded into a tubular shape having a diameter of 30 mm. The following small-diameter thin-walled dies, and air-cooling means for cooling the tube, water-cooling sizing means, water-cooling sizing means, and a take-up means for taking out the tubes, and a predetermined length of the tubes, which are sequentially arranged below in the gravity direction of the dies. And a cutting means for cutting the charging member. 2. The water-cooling sizing means includes a water tank having a small depth, a tapered portion formed at a central portion of the water tank, and a sizing pipe continuous with a central portion of the tapered portion. The apparatus of claim 1 wherein 3. The cooling water supply amount to the water cooling sizing means is 50 g / min to 6000 g / min, preferably 50 g / min to 2500 g / min, and the cooling water is controlled at about 30 ° C. Item 10. The apparatus according to Item 1. 4. The tube pulling speed by the tube pulling means and the weight of the tube drawn per unit length calculated from the shape and density of the tube are smaller than the weight of the tube material extruded from the die. The apparatus according to claim 1, wherein a ratio of the material extruded from the die to the weight is 10% to 30%. 5. An electrophotographic apparatus comprising: an electrophotographic photosensitive member, an electrostatic latent image forming unit, a unit for developing the formed electrostatic latent image, and a unit for transferring the developed image to a transfer material. An electrophotographic apparatus, wherein the charging member for performing the charging is a charging member obtained by coating an elastic body with a coating tube manufactured by the apparatus according to any one of claims 1 to 4.