JP2005189281A - Image forming apparatus component and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent image forming apparatus components and an image forming apparatus equipped with the same by controlling the value of a current flowing to the image forming apparatus component (roller) and further reducing matter (toner stain) sticking on the image forming apparatus component (charging roller) by coating an outer layer of a coated tube for a charging member with a mixture of conductive powder and insulating powder in order to easily obtain a desired current value. <P>SOLUTION: The image forming apparatus component which has at least a base part and a conductive coating part is characterized in that the conductive powder and insulating powder are provided on the conductive coating part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus component and an image forming apparatus using a conductive member, and more specifically, an image forming apparatus using a conductive member that controls a current value by mixing and interposing a specific powder on the surface. The present invention relates to a component and an image forming apparatus including the component.

  Conventionally, a number of methods are known as electrophotographic methods. In general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is formed with toner. Development is performed to obtain a visible image, and a toner image is transferred to a transfer material such as paper as necessary, and then the toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy. In addition, toner particles that are not transferred onto the transfer material but remain on the photoconductor are removed from the photoconductor by a cleaning process.

  Conventionally, a corona charger has been used as a charging device for electrophotography. In recent years, contact charging devices have been put to practical use instead. This is intended for low ozone and low power consumption, and among these, a roll charging method using a conductive roll as a charging member is particularly preferably used from the viewpoint of charging stability.

  In roll charging, a conductive elastic roll is brought into pressure contact with a member to be charged, and a voltage is applied thereto to charge the member to be charged.

  Specifically, since charging is performed by discharging from a charging member to an object to be charged, charging is started by applying a voltage higher than a certain threshold voltage. For example, when a charging roll is brought into pressure contact with an organic photoconductor (OPC photoconductor) having a photosensitive layer having a thickness of 25 μm, the photosensitivity can be obtained by applying a voltage of about 640 V or more in absolute value. The surface potential of the body starts to rise, and thereafter, the photoreceptor surface potential increases linearly with a slope of 1 with respect to the applied voltage. Hereinafter, this threshold voltage is defined as the charging start voltage Vth.

  That is, in order to obtain the photoreceptor surface potential Vd required for electrophotography, the charging roll needs a DC voltage higher than that required for image formation itself, that is, Vd + Vth. A method of charging by applying only the DC voltage to the contact charging member in this way is called DC charging.

  However, in DC charging, the resistance value of the contact charging member tends to fluctuate due to environmental fluctuations, etc., and Vth fluctuates when the film thickness changes due to the photoconductor being scraped, so the potential of the photoconductor is set to a desired value. It was difficult to do.

  For this reason, an AC + DC charging method in which a voltage obtained by superimposing an AC component having a peak-to-peak voltage of 2 × Vth or more on a DC voltage corresponding to a desired Vd is applied to the contact charging member in order to achieve further uniform charging. It is done. This is intended to equalize the potential due to AC, and the potential of the member to be charged converges to Vd, which is the center of the peak of the AC voltage, and is hardly affected by disturbances such as the environment.

  As the conductive member for charging, an example in which a surface layer is formed by a conductive seamless tube on a conductive support member is shown. Furthermore, a seamless tube made of a fluororesin is disclosed. In addition, a multilayer tube having a layer structure with different conductivity is disclosed. As a method related to manufacture as a charging member, a method of forming by insertion is mentioned as the conventional technique.

  To cover the support member with a seamless tube, the inner diameter of the seamless tube must be larger than the outer diameter of the support member to be covered, and the tube is shrunk and fitted by physical or chemical means, such as heat, or the seamless tube inner diameter The outer diameter of the support member to be coated is made smaller than that of the support member, and physical or chemical means such as air pressure is used to expand and fit the tube. A surface forming method using a crosshead extruder has been proposed.

  Such a method of forming a charging roll with a seamless tube can form a smooth surface by covering it with a seamless tube even if a foam is used as the elastic layer on the substrate. Uniform charging is easy.

  Although there is no restriction | limiting in particular in the thickness of such a seamless tube, Preferably it is 100-600 micrometers. Moreover, it does not restrict | limit at all to set it as a multilayer simultaneous forming tube.

  As a method for imparting conductivity to the seamless tube, there are generally an ion conduction method using a salt as a conductive agent and an electron conduction method using carbon black, a conductive metal oxide, a metal powder or the like as a conductive agent. When conductivity is provided by ionic conduction, there are problems that the environmental fluctuation of the resistance value is likely to increase, and that the salt is liable to contaminate the photoconductor because it contacts the electrophotographic photoconductor. Therefore, in the present invention, carbon black was used as a conductive agent.

  If the printer is used continuously, image defects may occur. One of the causes is considered to be adhesion of foreign matter on the image forming apparatus components inside the CRG. This phenomenon is likely to occur particularly in a high-temperature and high-humidity environment. If an image is printed in a low-temperature and low-humidity environment after continuous durability under a high-temperature and high-humidity environment, an image defect due to foreign matter tends to occur.

  For such adhesion of foreign matter, there is a choice that carbon black is easier to avoid surface contamination of the photoreceptor than the use of salt as described above, but it is attached to the surface material of the image forming apparatus component, for example, the charging roller. It is considered that the ease of occurrence is different depending on the chemical and physical compatibility with the toner and various additives as a kimono, and it is not generally decided.

  As a foreign matter adhesion improving method on the image forming apparatus, there are a method of preliminarily attaching a toner external additive to the roller surface (for example, Patent Document 1), and a method of using a silicone-based polymer for the roller surface layer. These differ from the present invention in that they define the material.

As an example in which powder is applied to a charging roller, a method of previously attaching a toner external additive (for example, Patent Document 1) or an insulating property (resistance value of 10 ⁸ Ω · cm or more) on the surface of a charging member In addition, there is a report that fogging can be prevented by attaching a powder having a particle size of preferably 20 μm or less (for example, Patent Document 2).

Further, when the abrasive in the toner component is attached on the charging roller, or when the particle size (P ₁₀ ) of the powder on the surface of the charging member and the ten-point average roughness F ₁ (μm) of the surface of the conductive member are used. , 0.01 ≦ P ₁₀ / F ₁ ≦ 20 (for example, Patent Document 3). These describe the application of a single powder, and the purpose is mostly an example of improved toner adhesion. Therefore, this is different from the current control by the mixed application of the present invention.
JP 2000-81759 A (page 12, FIG. 2) Japanese Patent Laid-Open No. 9-15935 (page 4, FIG. 2) Japanese Patent Laid-Open No. 11-31890 (page 30, FIG. 1)

  An object of the present invention is to provide a current flowing through an image forming apparatus component (roller) by applying a mixture of conductive powder and insulating powder to the outer layer of the charging member coating tube in order to easily obtain a desired current value. Control the value. It is another object of the present invention to provide a good image forming apparatus component by reducing adhesion (toner contamination) to the image forming apparatus component (charging roller) during printing.

  Another object of the present invention is to provide an image forming apparatus provided with the image forming apparatus component.

  According to the present invention, in an image forming apparatus component having at least a support portion and a conductive coating portion, the image forming apparatus has conductive powder and insulating powder on the conductive coating portion. Equipment parts are provided.

  According to the present invention, there is also provided an image forming apparatus provided with the image forming apparatus component.

  As described above, according to the present invention, it is possible to provide an image forming apparatus component that can easily adjust the resistance on the roller and has less toner contamination, and an image forming apparatus including the image forming apparatus component.

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

  Hereinafter, regarding the image forming apparatus component used in the present invention, the configuration, material, and manufacturing method will be exemplified.

  As its form, an elastic roller is used, which is composed of a core metal (conductive base), a conductive base layer (elastic layer), a coating layer (resistance layer), a powder layer, and the like.

  For example, FIG. 1 shows a configuration example of a charging roll which is an image forming apparatus component of the present invention. In the figure, 1 is a metal core (conductive substrate), 2 is a conductive base layer (elastic layer), 3 is a coating layer (resistance layer), 3 (a) is a low resistance conductive layer, and 3 (b) is high resistance. The conductive coating layer 3 (c) is the resistance adjusting powder layer according to the present invention. In this case, the conductive substrate 1, the elastic layer 2, and the conductive layer 3 (a) are collectively referred to as a support member. As the material of the core metal, a metal such as iron, copper, and stainless steel, a carbon dispersion resin, a metal or metal oxide dispersion resin, or the like is used as the conductive base. Examples of the conductive base layer (elastic layer) include rubber or sponge such as chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber and butyl rubber, and thermoplastic resins such as styrene butadiene, polyurethane, polyester and ethylene-vinyl acetate. Can be formed. These rubbers and resins may contain a conductive agent such as carbon black, metal and metal oxide particles.

  Regarding the provision of conductivity, for example, a metal vapor-deposited film, a conductive particle-dispersed resin, and a conductive resin are used in the cored bar. As the metal vapor-deposited film, vapor-deposited films such as aluminum, indium, nickel, copper, and iron are used. Can be mentioned. In addition, for providing conductivity to the base layer, examples of the conductive particle-dispersed resin include conductive particles such as carbon, aluminum, nickel and titanium oxide, urethane, polyester, vinyl acetate-vinyl chloride copolymer, and Examples thereof include those dispersed in a resin such as polymethyl methacrylate. Examples of the conductive resin include quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl aniline, polyvinyl pyrrole, polydiacetylene, and polyethyleneimine.

  As the covering layer (resistance layer), a conductive resin, a conductive particle-dispersed insulating resin, or the like can be used. Examples of the conductive resin include resins such as ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymer nylon, and polyvinylhydrin. Examples of conductive particle dispersion resins include small amounts of conductive particles such as carbon, aluminum, indium oxide, and titanium oxide in insulating resins such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethyl methacrylate. Examples are dispersed.

  As the charging roll, the structure of the present invention having a support member and a seamless tube is excellent in manufacturing stability, and can stably produce a medium resistance region which has been conventionally difficult to produce stably.

  Next, the coating layer will be described in more detail in the context of the present invention.

(Conductive coating member: About tube molding)
The conductive covering member according to the image forming apparatus component of the present invention is a seamless tube composed of a thermoplastic elastomer or a thermoplastic polymer resin, carbon black as a conductive agent, and other insulating powders.

  Specifically, examples of the thermoplastic elastomer include urethane, amide, styrene, olefin, ether, and fluorine elastomers, and examples of the thermoplastic polymer resin include acrylonitrile-butadiene-styrene. Examples thereof include resins, methacrylic resins, cellulose acetate resins, ethylene vinyl alcohol resins, polycarbonates, vinylidene fluoride resins, and polybutylene terephthalates.

  The use ratio of carbon black is preferably 10 to 60% by mass, and particularly preferably 20 to 40% by mass. When the ratio of carbon black is less than 10% by mass, there is a problem that durability as a charging roll is deteriorated because an increase in resistance when energized is used. On the other hand, when the proportion of carbon black is more than 60% by mass, there is a problem that the tube becomes too hard, the elastic properties are bad, and the coating cannot be performed.

The carbon black type may be any carbon black as long as the resistance value of the conductive coating member is 1 × 10 ⁶ to 1 × 10 ¹¹ Ω · cm and satisfies the above content, and two or more types of carbon black You may mix and use black.

  Examples of the carbon black used in the present invention include commercially available products such as Ketjen Black (manufactured by Lion Akzo), Printex, Special Black, Color Black (manufactured by Degussa), BLACK PEARLS (manufactured by Cabot), Asahi Carbon ( Asahi Carbon Co., Ltd.), Mitsubishi Carbon (Mitsubishi Chemical Co., Ltd.), Denka Black (Denki Kagaku Kogyo Co., Ltd.), Seest, Toka Black (manufactured by Tokai Carbon Co., Ltd.), and the like.

  Examples of other additives include conductive fillers, anti-aging agents, softeners, plasticizers, reinforcing agents, and fillers as necessary. As the conductive filler, graphite and metal oxide may be used in addition to the above carbon blacks. Examples of the metal oxide include titanium oxide and lead oxide.

(Conductive coating member: About powder coating)
The powder coating is to apply powder to adhere to the conductive coating member. The carbon black species at that time may be any carbon black as long as the resistance value after application to the conductive coating member satisfies 1 × 10 ⁶ to 1 × 10 ¹¹ Ω · cm, and other insulating properties. What is necessary is just to mix powder and to become an appropriate resistance value. The particle diameter is preferably 1 μm or less.

  Examples of the conductive powder used for the powder coating of the present invention include carbon, aluminum, nickel, and titanium oxide. In particular, as carbon black, Ketjen Black (made by Lion Akzo), Printex, Special Black, Color Black (made by Degussa), BLACK PEARLS (made by Cabot), Asahi Carbon (made by Asahi Carbon), Mitsubishi Carbon (Manufactured by Mitsubishi Chemical Corporation), Denka Black (manufactured by Denki Kagaku Kogyo Co., Ltd.), Seest, Toka Black (manufactured by Tokai Carbon Co., Ltd.), and the like.

  Examples of the insulating powder used for the powder coating of the present invention include silica, silica gel, hydrotalcite (DHT-4A), bentonite and calcium carbonate. The particle size of the insulating powder is also preferably 1 μm or less, and if it is larger than that, it becomes difficult to uniformly apply to the surface.

(About manufacturing method of charging member)
Next, as a method for producing a seamless tube for forming a conductive coating layer according to the present invention, a thermoplastic elastomer, a thermoplastic polymer resin, and carbon black are first kneaded together with necessary additives, and then pelletized. Next, the obtained pellet is made into a seamless tube by an extrusion molding machine. Then, after the molded seamless tube is coated on the support member, the powder is applied to the surface and wiped to obtain a charging member.

(Regarding image forming apparatus)
The electrophotographic photoreceptor, exposure means, development means, transfer means and cleaning means used in the present invention are not particularly limited.

  FIG. 2 shows an example of the configuration of an image forming apparatus including a process cartridge having the charging roll of the present invention as a primary charging unit.

  In FIG. 2, reference numeral 12 denotes a drum-shaped electrophotographic photosensitive member, which is rotationally driven at a predetermined peripheral speed (process speed) in the direction of an arrow about an axis. In the rotating process, the electrophotographic photosensitive member 12 is charged uniformly at a predetermined positive or negative potential on its peripheral surface by the charging member 11 of the present invention as a primary charging means having a power source 13, and then reflected light from the original. The exposure light 14 intensity-modulated in response to the time-series electric digital image signal of the target image information output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. Thus, electrostatic latent images corresponding to target image information are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 12.

  The formed electrostatic latent image is then visualized as a transferable particle image (toner image) by regular development or reversal development with charged particles (toner) in the developing means 15, and electrophotographic from a paper supply unit (not shown). A toner image formed and carried on the surface of the electrophotographic photosensitive member 12 is transferred to the transfer material 19 which is taken out and fed between the photosensitive member 12 and the transfer unit 17 in synchronization with the rotation of the electrophotographic photosensitive member 12. The images are sequentially transferred by the transfer means 17. At this time, a bias voltage having a polarity opposite to the charge held in the toner is applied to the transfer means from a bias power source (not shown).

  The transfer material 19 that has received the toner image transfer (in the case of a final transfer material (paper, film, etc.)) is separated from the electrophotographic photosensitive member surface, conveyed to the image fixing means 20, and subjected to a toner image fixing process. Printed out of the apparatus as an image formed product (print, copy). When the transfer material 19 is a primary transfer material (intermediate transfer material or the like), it is printed out after a fixing process after a plurality of transfer processes.

  The surface of the electrophotographic photosensitive member 12 after the toner image is transferred is cleaned by the cleaning means 16 after removal of deposits such as toner remaining after transfer. In recent years, a cleanerless system has been studied, and the transfer residual toner can be directly collected by a developing device or the like.

  In the present invention, a plurality of constituent elements such as the electrophotographic photosensitive member 12, the primary charging means 11, the developing means 15 and the cleaning means 16 described above are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from the main body of an image forming apparatus such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 11, the developing unit 15, and the cleaning unit 16 is integrally supported with the electrophotographic photosensitive member 12 to form a cartridge, and is attached to and detached from the apparatus main body using a guide unit 18 such as a rail of the apparatus main body. A flexible process cartridge 21 can be obtained.

  Further, when the image forming apparatus is a copying machine or a printer, the exposure light 14 is a reflected light or transmitted light from a document, or a signal is read by a document by a sensor, and laser beam scanning performed according to this signal is performed. The light emitted by driving the LED array or the liquid crystal shutter array.

  The image forming apparatus member of the present invention can be applied not only to copying machines but also to a wide range of image forming application fields such as laser beam printers, CRT printers, LED printers, FAX, liquid crystal printers, and laser plate making. .

[Example of seamless tube]
Hereinafter, although an example is given and demonstrated, this invention is not limited to an Example.

[Example 1]
Below, the manufacturing method of a co-extrusion 2 layer coating tube is demonstrated more concretely. For convenience, the surface side of the functional multilayer is expressed as an outer layer and the inner side is expressed as an inner layer.

<Inner layer material>
As an inner layer material, ether urethane elastomer resin 100 parts by mass, carbon black 1 (trade name “Ketjen Black EC”, Lion Akzo Co., Ltd.) 15-18 parts by mass, conductive titanium oxide 20 parts, magnesium oxide 10 Mass parts and 1 part by mass of calcium stearate are kneaded at 160 to 200 ° C. using a pressure kneader, cooled and pulverized, and pellets granulated at 160 to 210 ° C. with a single screw extruder are used.

<Outer layer material>
As the outer layer material, carbon black 1 (trade name “Ketjen Black EC”, Lion Akzo Co., Ltd.) mainly composed of 100 parts by mass of styrene-based thermoplastic elastomer resin (styrene-ethylene / butylene-olefin copolymer resin and polystyrene). ) 3-5 parts by mass, carbon black 2 (trade name “Special Black 250”, Degussa Japan) 20 parts by mass, magnesium oxide 10 parts by mass, calcium stearate 1 part by mass, using a pressure kneader 150-200 After cooling and kneading at 0 ° C., the pellets are cooled, pulverized with a pulverizer, and granulated at 160 ° C. to 200 ° C. with a single screw extruder.

<Tube molding>
Using the above pellets, after extrusion molding with a die having an inner diameter of φ18.0 mm and a point having an outer diameter of φ16.5 mm, through a sizing and cooling process, an inner diameter of φ10.90 mm and a layer thickness of 500 μm (inner layer) A seamless tube having a thickness of 400 μm and an outer layer of 100 μm was obtained. The seamless tube was covered with a foam elastic body layer having a core metal as a support member.

  Next, in order to interpose the powder on the obtained conductive coating layer, carbon (average particle size 0.04 μm) as conductive powder and hydrotalcite (DHT-4A) as insulating powder are used. , The average particle size of 0.4 μm) was mixed at a ratio of 50:50, and then applied onto a roller to remove other than adhering matter, thereby obtaining a charging member.

  In the case of FIG. 1, the inner layer 3 (a) is a low resistance conductive layer, the outer layer 3 (b) is a high resistance conductive layer, and the outer layer 3 (c) is a resistance adjusting powder layer corresponding to the present invention. is there. This charging roller was assembled in a process cartridge shown in FIG.

  The following evaluation was performed on the charging member obtained as described above, and the results are shown in Table 1.

  Current measurement: As shown in FIG. 3, the charging roller was brought into contact with the SUS drum, and the current value (DC av.) Flowing from the roller to the SUS drum was measured by applying 300 Hz, 500 Vpp, and −100 mV superimposed. . The desired current value range is 400 to 1000 (−μA), and if it is out of the range, problems on the image such as fogging occur. Even within the range, a problem on the image may occur due to other factors.

  Toner adhesion: 100 sheets were continuously printed at room temperature using an LBP main body (HP Laser Jet 4100) and CRG (C8061X), and then the toner adhesion on the surface of the charging member was visually confirmed. In the evaluation, ○ indicates that the toner is difficult to adhere, and X indicates that the toner is easily attached.

[Examples 2-3]
A charging member was obtained in the same manner as in Example 1 except that the mixed concentration of the powder in Example 1 was changed (carbon / hydrotalcite mass ratio = 0.1 to 0.01). Moreover, the same evaluation as Example 1 was performed. The results are shown in Table 1.

[Comparative Example 1]
A charging member in which powder was not applied on the conductive coating layer was obtained in the same manner as in Example 1, and the same evaluation was performed. The results are shown in Table 1.

  As can be seen from Table 1, in the example, the current value of the roller could be changed from −596 μA to −9030 μA depending on the mixing ratio of the powder. Furthermore, while the roller in Comparative Example 1 on which the powder was not applied easily adheres to the toner, in Examples 1 to 3, a roller on which the toner hardly adheres was obtained.

It is a figure which shows the structural example of the charging roll which is image forming apparatus components of this invention. 1 is a diagram illustrating an example of the configuration of an image forming apparatus including a process cartridge having a charging roll of the present invention as a primary charging unit. It is a figure which shows schematic structure of the current measurement in an Example.

Explanation of symbols

1 Core (conductive base)
2 Conductive base layer (elastic layer)
3 Coating layer (resistance layer)
3 (a) Low resistance conductive layer 3 (b) High resistance conductive coating layer 3 (c) Resistance adjusting powder layer 11 Charging means 12 Electrophotographic photoreceptor 13 Power source 14 Exposure light 15 Developing means 16 Cleaning means 17 Transfer means 18 Guide means 19 Transfer material 20 Fixing means 21 Process cartridge

Claims (6)

  An image forming apparatus component having at least a support portion and a conductive coating portion, wherein the conductive coating portion includes conductive powder and insulating powder.   The image forming apparatus component according to claim 1, wherein an average particle diameter of the powder is 1 μm or less.   The image forming apparatus component according to claim 1, wherein the conductive coating portion is a seamless tube.   The image forming apparatus component according to claim 3, wherein the image forming apparatus component is a roller-shaped member.   The image forming apparatus component according to claim 4, wherein the roller-shaped member is selected from the group consisting of a charging roller, a transfer roller, a developing roller, and a developer regulating roller.   An image forming apparatus comprising the image forming apparatus component according to claim 1.

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