JP2009139532A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent developing device which can obtain fog-free images of high density, even if a developing roller, with a direct covering layer formed on the periphery of a conduct shaft body is mounted on an image forming apparatus and a large number of sheets (e.g. 5,000 sheets) are printed, and which will not produce soiling inside the device. <P>SOLUTION: The developing device includes a means for forming a thin layer of charged non-magnetic one-component toner on the surface of the developing roller by means of a restricting blade, with the developing roller having the direct covering layer on the periphery of the conduct shaft body; a means for developing an electrostatic latent image on the surface of a photoreceptor, without causing the thin layer of the non-magnetic one-component toner come into contact with the photoreceptor, thereby rendering the electrostatic latent image visible; and a means for removing, by the use of a destaticizing sheet, electric charges of the non-magnetic one-component toner remaining on the surface of the developing roller, after the image is rendered visible. In the developing device, the charging polarity of the electricity removal sheet is same as the charging polarity of the non-magnetic single-component toner. The surface resistance value of the destaticizing sheet is 1×10<SP>10</SP>to 1×10<SP>16</SP>Ωcm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device. Specifically, means for forming a thin layer of nonmagnetic monocomponent toner on the surface of the developing roller having a coating layer directly provided on the outer periphery of the conductive shaft, and bringing the thin layer of nonmagnetic monocomponent toner into contact with the photoreceptor In particular, the present invention relates to a developing device having a means for developing and visualizing an electrostatic latent image on the surface of a photosensitive member, and a means for removing charges of a non-magnetic one-component toner remaining on the surface of the developing roller after the visualization with a charge removing sheet.

  In recent years, image forming technologies such as copying machines, printers, and facsimiles have been remarkably developed, and in particular, an image forming apparatus based on an electrophotographic system is often used. In addition, as performance of related technologies such as personal computers is improved, there is an increasing demand for devices capable of forming color images and compact, lightweight, and low-cost image forming devices, and further improvements and improved performance are desired. .

  The electrophotographic developer used in the image forming apparatus includes a two-component developer composed of a toner and a carrier and a one-component developer composed of a nonmagnetic or magnetic toner. Since the developing device using the one-component developer does not use a carrier, there is an advantage that a stirring device for mixing the carrier and the toner and a control for making the mixing ratio of the toner and the carrier constant are not required.

  Further, the non-magnetic one-component developing method using non-magnetic one-component toner does not use a magnet for the developing roller, and thus is preferably used for a printer that is smaller and requires a lower price.

  Among the non-magnetic one-component development methods, the non-contact development method in which development is performed by separating the photosensitive member and the developing roller is advantageous for high image quality and colorization.

  In addition, with the spread of low-cost printers, development of technology to reduce the size and price by developing a built-in developing roller in the developing cartridge and providing the function of the developing device has progressed, and the type of image that replaces the toner cartridge Forming devices have attracted attention.

  Furthermore, due to the recent increase in consideration for the environment, toner replenishment type development cartridges have been developed, in which toner is replenished from a type that replaces the cartridge to a developing device that incorporates a developing roller, and the developing device is used multiple times. Yes. Accordingly, there is a strong demand for simple maintenance (long cartridge life), and resistance to deterioration during repeated use is required.

Recently, the surface of the shaft body is directly covered with the outer surface of the developing roller or shaft body subjected to surface processing such as blasting without providing an elastic layer in order to reduce the cost and reduce the size and weight of the developing roller. A developing device using a developing roller provided with a layer has been proposed (see, for example, Patent Document 1 and Patent Document 2).
JP 2001-66876 A JP 2002-14535 A

  However, if a developing roller having no elastic layer, that is, a developing roller having a coating layer directly provided on the outer periphery of the conductive shaft is mounted on the image forming apparatus to form an image, a high-density printed image is continuously obtained. In some cases, the image was not printed, or the print was fogged or toner spilled around the developing device and the inside of the apparatus was stained.

  In the present invention, even when a developing roller having a coating layer directly provided on the outer periphery of a conductive shaft is mounted on an image forming apparatus and a large number of sheets (for example, 5000 sheets) are printed, an image with high density and no fogging is continued. It is an object of the present invention to provide an excellent developing device which is obtained and does not cause in-machine contamination.

  The present invention is achieved by adopting the following configuration.

1. Means for forming a thin layer of non-magnetic one-component toner to which a charge is applied using a regulating blade on the surface of a developing roller in which a coating layer is directly provided on the outer periphery of the conductive shaft;
Means for developing and visualizing an electrostatic latent image on the surface of the photoreceptor without bringing the thin layer of the non-magnetic one-component toner into contact with the photoreceptor;
In a developing device having a means for discharging charges of the non-magnetic one-component toner remaining on the surface of the developing roller after visualization by a discharging sheet,
The charge polarity of the charge removal sheet is the same as the charge polarity of the non-magnetic one-component toner,
The developing device characterized in that the surface resistance value of the charge eliminating sheet is 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm.

  2. 2. The developing device as described in 1 above, wherein the voltage applied to the developing roller and the charge eliminating sheet is the same potential.

  The developing device of the present invention is capable of continuously obtaining a high-density and non-fogging image even when a developing roller having a coating layer directly provided on the outer periphery of the conductive shaft is mounted on the image forming apparatus and printing a large number of sheets. In addition, it has an excellent effect of preventing in-machine contamination.

  Currently, in order to respond to the small size, light weight, and low cost of color image forming apparatuses, non-magnetic one-component toner (hereinafter also simply referred to as “one-component toner” or “toner”) and a developing roller provided with a coating layer directly on the outer periphery of a conductive shaft. Development devices that combine these are being studied.

  A developing roller that does not have an elastic layer, that is, a developing roller in which a coating layer is provided directly on the outer periphery of a conductive shaft body has advantages such as low manufacturing cost and high productivity. However, there are disadvantages due to the lack of an elastic layer.

  The flexible elastic layer has a function of reducing mechanical stress applied to the toner when a charge is applied to the toner by the regulating blade.

  In the developing roller not having the function of the elastic layer, when the toner is charged with the regulating blade, mechanical stress is applied, and the external additive fixed on the surface of the toner is buried in the toner and the toner deteriorates. . As a result, as the printing progresses, the amount of charge decreases significantly. When the charge amount is lowered, quality problems such as a decrease in print image density, fogging in the print, and spilling of toner in the machine occur.

  At present, it is difficult to secure a constant charge amount because the charge amount does not decrease even when a large number of prints are made using a developing roller having a coating layer directly provided on the outer periphery of the conductive shaft.

  In order to solve the problem that the charge amount of the non-magnetic one-component toner decreases due to the use of a developing roller having no elastic layer, the present inventors have determined the charge polarity of the non-magnetic one-component toner and the charge polarity of the charge removal sheet, The surface resistance of the static elimination sheet was examined.

  Conventionally, the charge removal sheet is imparted with conductivity and resistance adjusted, and the charge amount of the development residual toner on the developing roller is configured to approach zero. As a result, it was possible to easily scrape off the toner on the supply roller.

  However, when a large number of sheets are printed, the toner deteriorates and the charge amount of the toner decreases. When the charge amount decreases, reversely charged toner is likely to be generated by passing through the charge removal sheet (the charge is discharged to the opposite polarity instead of zero). That is, when the toner is recharged by the regulating blade, a sufficient charge amount cannot be applied to the toner.

  The present invention maintains a constant charge amount (charge at the development position) with a regulating blade even for deteriorated toner by maintaining the charge amount (charge amount at the charge removal position) of the toner that has passed through the charge removal sheet at a certain value. It was found that the amount could be given.

  As a result, even when a large number of sheets are printed, a printed image with high density and no fogging can be obtained, and toner spillage can be prevented from occurring around the developing device.

  Hereinafter, the present invention will be described in detail.

<Image formation process>
The developing device of the present invention is used by being mounted on a full-color image forming apparatus. In the full-color image forming apparatus, a print image is formed by the following image forming process.
1. 1. Send the toner from the hopper to the supply unit. 2. The toner is conveyed to the developing roller by the supply roller and further to the position of the regulating blade by the developing roller. 3. A toner thin layer is formed by the regulating blade and the developing roller, and at the same time, the toner is charged. 4. A thin layer of charged toner is conveyed to the development section. 5. The electrostatic latent image on the photosensitive member is developed with the conveyed toner, and the electrostatic latent image is visualized. 6. Toner that has not contributed to visualization is transported to the static elimination section. 7. The toner conveyed to the neutralization unit is neutralized by the neutralization sheet. 8. The discharged toner is collected by the supply roller. The collected toner is returned to the toner buffer chamber for use.

  Next, the static elimination sheet will be described.

<Static elimination sheet>
The neutralization sheet used in the present invention has the same charging polarity as that of the non-magnetic one-component toner, and the surface resistance value is 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm, preferably 1 × 10 ^11. ˜1 × 10 ¹⁴ Ω · cm.

  By using a neutralization sheet having the same polarity as the non-magnetic one-component toner, the ability to neutralize the charge amount of the toner is reduced, and the charge amount of the deteriorated toner is not neutralized to the opposite polarity.

  In the present invention, the charging polarity is obtained by charging two objects by contact or friction and arranging them in the order of positive charge to negative charge.

  The charge eliminating sheet may also serve as a seal member for preventing toner leakage.

  The material of the static elimination sheet is a fluororesin of polytetrafluoroethylene (PTFE), tetrafluoroethylene, polyvinylidene fluoride (PVDF), tetrafluoroethylene perfluoropropyl vinyl ether (PFA) for negatively charged toner. Polyester resin or the like can be used.

  For positively charged toner, acrylic resin, triacetate resin (TAC), polyamide (nylon) resin, silicone resin, or the like can be used.

  The surface resistance value of the static elimination sheet can be determined by the following measurement method.

  FIG. 1 is a schematic diagram illustrating a method for measuring the surface resistance value of a static elimination sheet.

The measurement method is
(1) A measurement sample having a size that can be measured with an HR probe is prepared. (2) A sample prepared on the counter electrode is placed, and an HR probe (diameter 50 mm) conforming to JIS-K6911 is placed on the sample. (3) Connect the counter electrode and probe to a microammeter (using a digital ultra-high resistance / microammeter “R8340A” (manufactured by Advantest)), and apply a voltage of 500 V between the counter electrode and the probe. . The measurement environment is a temperature of 23 ° C. and a humidity of 45%.

  Next, the static elimination sheet will be described.

  The neutralization sheet of the present invention is preferably used in the form of a neutralization member fixed by a member such as a pad in order to attach the neutralization sheet to the developing device with high accuracy.

  As the member for fixing the static elimination sheet, a material capable of fixing the static elimination sheet to the pad by an adhesive, double-sided tape, ultrasonic welding or the like is used. Specifically, a resin member, a foamed resin member, a metal member, etc. can be mentioned.

  It is preferable to set the discharging member to the developing device in a state in which the toner and the discharging sheet have a wide rubbing width and the toner is not deteriorated by contact.

  FIG. 2 is a schematic diagram illustrating an example of a charge removal member in which a charge removal sheet is fixed by a holder.

  In FIG. 2, 50 is a static elimination member, 53 is a pad, 52 is a static elimination sheet, and 51 is a holder.

  FIG. 2A shows a static elimination member configured to fix the back surface of the static elimination sheet to the holder and to make the front surface (the non-fixed side) contact and contact the developing roller. (B) shows a configuration in which a static elimination sheet provided with a pressing force equalizing member (pad) on the back surface of the static elimination sheet is fixed to a holder, and the surface (non-fixed side) is in contact with and in contact with the developing roller. (C) shows a static eliminating member having a configuration in which one side of the back surface of the static elimination sheet is fixed to a holder, and a flat surface or curved surface of the front surface (non-fixed side) is brought into contact with and contacted with the developing roller.

  Among these, the structure in which the neutralization sheet provided with a pad on the back surface of the neutralization sheet of (b) is fixed to the holder, and the surface or anti-fixation side plane or aspect is in contact with the developing roller is uniform pressing force. It is easy to ensure and is preferable.

  The charge removing sheet has the same charging polarity as that of the non-magnetic one-component toner. By using a toner having the same polarity as the non-magnetic one-component toner, the ability to remove the charge amount of the toner is lowered, and the charge amount of the deteriorated toner is not discharged to the opposite polarity.

  The static elimination sheet is attached to the developing roll with a rubbing width of 1 to 3 mm.

  The pressing force of the discharging member that contacts the developing roller is determined by the material, thickness and surface roughness of the discharging sheet constituting the discharging member, the material and hardness of the pressing force equalizing member (pad), and the discharging member being pushed into the developing roller. Can be controlled by amount, nip width, etc.

  The push-in amount in the present invention refers to the amount (height) that the charge-removing member is depressed and depressed when the charge-removing member is pressed against the developing roller. The nip width refers to the width of the static eliminating sheet that comes into contact with the developing roller when the static eliminating member is pushed in.

  Next, the developing roller will be described.

<Development roller>
The developing roller used in the present invention has a conductive coating layer formed on the outer periphery of a conductive shaft.

  FIG. 3 is a schematic diagram of the layer structure showing an example of the developing roller according to the present invention.

  In FIG. 3, 25 is a developing roller, 11 is a conductive shaft, 12 is a coating layer, 13 is a lower layer, and 14 is an upper layer.

  FIG. 3A is a schematic view of a developing roller in which a coating layer 12 is provided on the outer periphery of the conductive shaft body 11. As shown in FIG. 3B, the coating layer has a single-layer coating layer 12 on the outer periphery of the conductive shaft 11, and the outer periphery of the conductive shaft 11 as shown in FIG. 3C. In order to improve the adhesion between the shaft body and the upper layer, a lower layer (intermediate layer) 13 may be provided, and an upper layer 14 may be provided thereon.

The coating layer according to the present invention has conductivity. The conductivity of the coating layer is represented by a volume resistance value, and the volume resistance value is preferably 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω · cm.

  FIG. 4 is a configuration diagram illustrating a method for measuring the volume resistance value of the developing roller.

  In FIG. 4, 1 is a counter electrode (metal drum), 25 is a developing roller, 3 is a DC power source, and 4 is an ammeter.

  The volume resistance of the coating layer was pressed at 9.8 N together with the weight of the counter electrode 1 and applied with 100 V from the DC power supply 3 while rotating the counter electrode 1 and the developing roller 25 to be measured in the direction of the arrow for 10 seconds. Immediately after aging, the applied voltage is changed to +2 V, the current value is measured by the ammeter 4 for 5 seconds, the average of the current values for 5 seconds at the applied voltage 2 V is obtained, and is calculated.

Measuring instrument: Measuring instrument of FIG. 4 Measuring condition: The linear velocity of the counter electrode and the developing roller is rotated at a constant speed of 5 cm / sec. Applied voltage: 2 V
Measurement environment: 20 ° C., 50 RH%.

  Next, the nonmagnetic one-component toner will be described.

<< Non-magnetic 1-component toner >>
The non-magnetic one-component toner used in the present invention has a positively charged polarity or a negatively charged polarity that can be heat-fixed and manufactured by a known method.

  Specific examples of the resin constituting the one-component toner include a polyester resin and an acrylic resin.

  The charge polarity of the non-magnetic one-component toner can be made positive or negative by selecting the type of resin and charge control agent constituting the toner.

The median diameter (D ₅₀ ) based on the volume of the toner is preferably 3.0 to 9.0 μm from the viewpoint of obtaining a high-quality toner image.

The median diameter (D ₅₀ ) on a volume basis can be measured and calculated using a device in which a computer system for data processing (manufactured by Coulter) is connected to Multisizer 3 (manufactured by Coulter).

As a procedure for measuring the median diameter (D ₅₀ ) on a volume basis, 0.02 g of one-component toner and 20 ml of a surfactant solution (for example, neutral detergent containing a surfactant component is used for the purpose of dispersing one-component toner). (Surfactant solution diluted 10-fold with water) and ultrasonic dispersion is performed for 1 minute to prepare a one-component toner dispersion. This one-component toner dispersion is injected into a beaker containing ISOTON II (manufactured by Coulter, Inc.) in a sample stand with a pipette until the measured concentration reaches 5 to 10%, and the measuring machine count is set to 30000. To do. The aperture diameter of the Coulter Multisizer is 50 μm.

  The production method of the non-magnetic one-component toner is not particularly limited, and can be produced by a known production method, specifically, a pulverization method or a polymerization method.

  The charge amount of the one-component toner depends on the materials constituting the one-component toner, such as resin, charge control agent, and external additive, and materials of the developing roller and the regulating blade.

  The charge amount of the one-component toner on the developing roller is measured by the following measuring method.

1. 1. The mass: W1 (g) of a toner collecting unit equipped with filter paper (T100A047A: manufactured by Advantech) is measured with an analytical balance (CP224S type: manufactured by Sartorius). 2. Mount the toner collection unit on the suction pump. The toner in the area of about 7 cm ^{2 on} the surface of the developing roller in the toner cartridge is collected on the filter paper by a suction pump, and the charge amount Q (μC) of the collected toner transferred to the toner collecting unit is digital electrometer 3. Obtained by charge amount measurement mode (R8252 type: manufactured by ADC Corporation) 4. Remove the toner collecting unit from the suction pump and measure the mass of the toner collecting unit after collecting the toner: W2 (g). The toner charge amount Q / M (μC / g) is obtained from Equation 1. Equation 1 Charge amount = Q / M = Q / (W2−W1)
Next, the developing device of the present invention will be described.

<Developing device>
An image forming method for visualizing a latent image by holding and conveying the one-component toner on the surface of a developing roller, attaching the one-component toner to a latent image formed on the surface of a photoreceptor Used for.

  FIG. 5 is a schematic sectional view showing an example of the developing device of the present invention.

  The developing device 20 shown in FIG. 5 has a buffer chamber 26 adjacent to the developing roller 25, and a hopper 27 and the like adjacent to the buffer chamber 26.

  In the buffer chamber 26, a regulating blade 28, which is a toner regulating member, is disposed in pressure contact with the developing roller 25. The regulating blade 28 regulates the charge amount and adhesion amount of the toner on the developing roller 25. Further, an auxiliary blade 29 for assisting in regulating the toner charge amount and the adhesion amount on the developing roller 25 may be further provided on the downstream side of the regulating blade 28 with respect to the rotation direction of the developing roller 25.

  A supply roller 30 is pressed against the developing roller 25. The supply roller 30 is driven to rotate in the same direction as the developing roller 25 (counterclockwise direction in the drawing) by a motor (not shown). The supply roller 30 has a conductive cylindrical conductive shaft and a foam layer formed of urethane foam or the like on the outer periphery of the conductive shaft.

  The hopper 27 contains a toner T that is a non-magnetic one-component toner. The hopper 27 is provided with a rotating body 31 for stirring the toner T. A film-like conveying blade is attached to the rotating body 31, and the toner T is conveyed by the rotation of the rotating body 31 in the arrow direction. The toner T conveyed by the conveying blades is supplied to the buffer chamber 26 via a passage 32 provided in a partition wall that separates the hopper 27 and the buffer chamber 26. The shape of the conveying blade is bent while the toner T is conveyed in front of the rotation direction of the blade with the rotation of the rotating body 31 and returns to a straight state when the left end of the passage 32 is reached. Thus, the toner T is supplied to the passage 32 by returning the shape of the blade straightly through the curved state.

  The passage 32 is provided with a valve for closing the passage 32. This valve is a film-like member, one end of which is fixed to the upper side of the right side of the passage 32 of the partition wall. When the toner T is supplied from the hopper 27 to the passage 32, the valve 32 is pushed rightward by the pressing force from the toner T. Can be opened. As a result, the toner T is supplied into the buffer chamber 26.

  In the developing device 20, the developing roller 25 is rotationally driven in the arrow direction during image formation, and the toner in the buffer chamber 26 is supplied onto the developing roller 25 by the rotation of the supply roller 30. The toner T supplied onto the developing roller 25 is charged and thinned by the regulating blade 28 and the auxiliary blade 29, and then transported to a region facing the image carrier, where the electrostatic latent image on the image carrier is transferred. It is used for development. The toner that has not been used for development is neutralized by the neutralizing member 50 having the neutralizing sheet 52 as the developing roller 25 rotates, and after the electrostatic adhesion force between the developing roller and the toner is reduced, the toner is discharged by the supply roller 30. It is scraped off and collected from the developing roller 25.

  Next, the voltage applied to the developing roller and the charge removal sheet will be described.

  FIG. 6 is a schematic diagram illustrating a developing device in which the voltage applied to the developing roller and the charge removal sheet is the same potential.

  By setting the voltage applied to the developing roller and the charge eliminating sheet to the same potential, the charge of the non-magnetic one-component toner remaining on the surface of the developing roller can be controlled within a preferable range by the charge eliminating sheet.

  The regulating blade (regulating member) used in the present invention is preferably an elastic blade, an elastic roller, or the like, and is made of a friction charging material suitable for charging the toner to a desired polarity.

  In the present invention, metal plates such as SUS and phosphor bronze, silicone rubber, urethane rubber, styrene-butadiene rubber and the like are suitable. Further, an organic resin layer such as polyamide, polyimide, nylon, melamine, melamine-crosslinked nylon, phenol resin, fluorine resin, silicone resin, polyester resin, urethane resin, styrene resin, or the like may be provided. It is also possible to use conductive rubber, conductive resin, etc., or to disperse fillers such as metal oxide, carbon black, inorganic whiskers, inorganic fibers and charge control agents in the blade rubber and resin. It is preferable because it imparts charge imparting properties and can charge the toner appropriately.

  The contact pressure between the regulating blade and the developing roller is preferably 3 to 250 N / m, and particularly preferably 5 to 30 N / m, as the line pressure in the sleeve bus direction. By setting the contact pressure to 3 to 250 N / m, the toner conveyance amount is specified, and the toner charge amount distribution becomes sharp.

  Next, a full color image forming apparatus using the developing device of the present invention will be described.

<Image formation>
FIG. 7 is a schematic cross-sectional view showing an example of a full-color image forming apparatus.

  In the full-color image forming apparatus shown in FIG. 7, a charging brush 111 and the like for uniformly charging the surface of the photosensitive drum 10 to a predetermined potential are provided around the photosensitive drum 10 that is rotationally driven.

  Further, a laser scanning optical system 20 for scanning and exposing the photosensitive drum 10 charged by the charging brush 111 with a laser beam is provided. The laser scanning optical system 20 includes a laser diode, a polygon mirror, and an fθ optical element. The print data for each of yellow, magenta, cyan, and black is transferred from the host computer to the control unit. The laser scanning optical system 20 sequentially outputs the laser beam as a laser beam based on the print data for each color, scans and exposes the photosensitive drum 10, and thereby the static image for each color is formed on the photosensitive drum 10. Electro latent images are sequentially formed.

  In addition, the full-color developing device 30 that supplies full-color development to the photosensitive drum 10 on which the electrostatic latent image is formed in this manner, performs yellow, magenta, cyan, and black around the support shaft 33. Four color-developing units 31Y, 31M, 31C, and 31Bk each containing non-magnetic one-component toner are provided. The developing units 31Y, 31M, 31C, and 31Bk rotate around the support shaft 33, and It is guided to a position facing the photosensitive drum 10.

  Further, in each of the developing devices 31Y, 31M, 31C, and 31Bk in the full-color developing device 30, as shown in FIG. 7, the toner is regulated on the outer peripheral surface of the developer carrier (developing roller) 25 that rotates and conveys the toner. The member is in pressure contact, and the toner regulating member regulates the amount of toner conveyed by the developing roller 25 and charges the conveyed toner. In the full-color developing device 30, two toner regulating members may be provided in order to appropriately regulate and charge the toner conveyed by the developing roller.

  Then, whenever the electrostatic latent image of each color is formed on the photosensitive drum 10 by the laser scanning optical system 20 as described above, the full-color developing device 30 is rotated around the support shaft 33 as described above. Then, the developing devices 31Y, 31M, 31C, and 31Bk containing the corresponding color toners are sequentially guided to positions facing the photosensitive drum 10, and the developing rollers 25 in the developing devices 31Y, 31M, 31C, and 31Bk are sequentially guided. Thus, development is performed by sequentially supplying charged toner of each color toward the photosensitive drum 10 on which the electrostatic latent images of each color are sequentially formed as described above.

  Further, an endless intermediate transfer belt 40 that is rotationally driven is provided as an intermediate transfer body 40 at a position downstream of the full-color developing device 30 in the rotation direction of the photosensitive drum 10. Is driven to rotate in synchronization with the photosensitive drum 10. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 41 so as to come into contact with the photosensitive drum 10, and a portion of a support roller 42 that supports the intermediate transfer belt 40 includes: A secondary transfer roller 43 is rotatably provided, and the recording material S such as recording paper is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43.

  Further, a cleaner 50 that scrapes off the toner remaining on the intermediate transfer belt 40 is provided in a space between the full-color developing device 30 and the intermediate transfer belt 40 so as to be able to contact with and separate from the intermediate transfer belt 40. ing.

  Further, the paper feeding means 60 that guides the recording material S such as plain paper to the intermediate transfer belt 40 includes a paper feeding tray 61 that accommodates the recording material S and the recording material S that is accommodated in the paper feeding tray 61 one by one. The recording material S fed in synchronization with the paper feed roller 62 for feeding paper and the image formed on the intermediate transfer belt 40 is sent between the intermediate transfer belt 40 and the secondary transfer roller 43. The recording material S sent between the intermediate transfer belt 40 and the secondary transfer roller 43 in this way is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43. The toner image is pressed and transferred from the intermediate transfer belt 40 to the recording material S.

  On the other hand, the recording material S on which the toner image is pressed and transferred as described above is guided to the fixing device 70 by the conveying means 66 constituted by an air suction belt or the like, and is transferred by the fixing device 70. The toner image is fixed on the recording material S, and then the recording material S is discharged onto the upper surface of the apparatus main body 100 through the vertical conveyance path 80.

  Next, the operation of forming a full color image using this full color image forming apparatus will be specifically described.

  First, the photosensitive drum 10 and the intermediate transfer belt 40 are rotationally driven in the respective directions at the same peripheral speed, and the photosensitive drum 10 is charged to a predetermined potential by the charging brush 11.

  The photosensitive drum 10 thus charged is exposed to a yellow image by the laser scanning optical system 20 to form an electrostatic latent image of the yellow image on the photosensitive drum 10. The yellow image is developed by supplying the yellow toner charged by the toner regulating member as described above from the developing device 31Y in which the yellow toner is accommodated in the photosensitive drum 10, and the yellow toner image is thus formed. The intermediate transfer belt 40 is pressed against the body drum 10 by the primary transfer roller 41, and the yellow toner image formed on the photosensitive drum 10 is primarily transferred to the intermediate transfer belt 40.

  After the yellow toner image is transferred to the intermediate transfer belt 40 in this way, the full-color developing device 30 is rotated around the support shaft 33 as described above, and the developing device 31M containing magenta toner is exposed to light. As in the case of the yellow image described above, the magenta image is exposed to the photosensitive drum 10 charged by the laser scanning optical system 20 to form an electrostatic latent image. The electrostatic latent image is developed by a developing device 31M containing magenta toner, and the developed magenta toner image is primarily transferred from the photosensitive drum 10 to the intermediate transfer belt 40. Black image exposure, development and primary transfer are sequentially performed, and yellow, magenta, cyan, and black toner images are sequentially superimposed on the intermediate transfer belt 40. To form a toner image of Rukara.

  When the final black toner image is primarily transferred onto the intermediate transfer belt 40, the recording material S is fed between the secondary transfer roller 43 and the intermediate transfer belt 40 by the timing roller 63, and the secondary transfer roller. The recording material S is pressed against the intermediate transfer belt 40 by 43, and the full color toner image formed on the intermediate transfer belt 40 is secondarily transferred onto the recording material S.

  When the full-color toner image is secondarily transferred onto the recording material S in this way, the recording material S is guided to the fixing device 70 by the conveying means 66, and the full-color toner transferred by the fixing device 70 is transferred. The image is fixed on the recording material S, and then the recording material S is discharged onto the upper surface of the apparatus main body 1 through the vertical conveyance path 80.

  The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

<Production of static elimination member>
A static elimination member was produced as follows.

<Preparation of static elimination member 1>
A “static elimination member 1” having the configuration shown in FIG. 2B was produced using the “static elimination sheet 1” having the following characteristics.

Static elimination sheet 1
Material: PTFE (Polyfluoroethylene)
Thickness: 80 μm
Charging polarity: Minus Surface resistance: 1 × 10 ⁸ Ω · cm
<Preparation of static elimination members 2-7>
“Charging members 2 to 7” were prepared in the same manner except that the discharging sheet 1 used in the preparation of the discharging member 1 was changed to the discharging sheet shown in Table 1.

<Production of developing roller>
A developing roller was produced as follows.

  As a conductive shaft body of the developing roller, a hollow cylindrical conductive shaft body of SUS303 was prepared. This is referred to as a “conductive shaft”.

  Carbon black "Ketjen Black EC300J (Lion Corporation)" 20 parts by mass, tetramethyl ammonium chloride 2. 0 parts by mass and 20 parts by mass of “fluororesin particles” were dispersed using a sand mill for 2 hours to prepare a coating solution for forming a surface layer. This is referred to as “surface layer forming coating solution”.

  The “surface layer forming coating solution” is spray-coated on the outer peripheral surface of the “conductive shaft” so that the film thickness after drying becomes 5 μm, and dried at 100 ° C. for 1 hour to form a “coating layer”. A “developing roller” was produced.

<Production of toner>
Negatively charged toner and positively charged toner were prepared as follows.

<Preparation of negatively charged toner>
(Preparation of resin particles)
In a container equipped with a stirrer, 72.0 parts by mass of wax (pentaerythritol tetrastearate) is added from 115.1 parts by mass of styrene, 42.0 parts by mass of n-butyl acrylate, and 10.9 parts by mass of methacrylic acid. Was added to the monomer mixture solution, heated to 80 ° C. and dissolved to prepare a monomer solution.

  On the other hand, 7.08 parts by mass of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS) was dissolved in 2760 parts by mass of ion-exchanged water in a container equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction apparatus. A surfactant solution (aqueous medium) was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. Next, the monomer solution (80 ° C.) was mixed and dispersed in the surfactant solution (80 ° C.) with a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path, and uniformly An emulsified liquid in which emulsified particles (oil droplets) having a dispersed particle diameter were dispersed was prepared.

  An initiator solution in which 0.84 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion, and this system was heated at 80 ° C. for 3 hours. The polymerization reaction was carried out by stirring. A solution obtained by dissolving 7.73 parts by mass of a polymerization initiator (KPS) in 240 parts by mass of ion-exchanged water was added to the obtained reaction solution. After 15 minutes, the temperature was adjusted to 80 ° C., and then styrene 383.6. A mixed solution consisting of part by mass, 140.0 parts by mass of n-butyl acrylate, 36.4 parts by mass of methacrylic acid and 12 parts by mass of n-octyl mercaptan was dropped over 100 minutes, and the system was heated at 80 ° C. for 60 minutes. After stirring, the system was cooled to 40 ° C. to prepare a dispersion of resin particles containing wax (hereinafter also referred to as “latex (1)”).

(Preparation of colorant dispersion (1))
On the other hand, 9.2 parts by mass of sodium n-dodecyl sulfate was stirred and dissolved in 160 parts by mass of ion-exchanged water. While stirring this solution, 20 parts by mass of carbon black “Mogal L (Cabot)” was gradually added as a colorant, and then a mechanical disperser “Claremix” (M Technique) was used. A dispersion of colorant particles (hereinafter referred to as “colorant dispersion (1)”) was prepared by dispersion treatment. When the particle diameter of the colorant particles in the colorant dispersion (1) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm.

(Preparation of colorant dispersion (2))
In the colorant dispersion (1), the colorant was prepared in the same manner as in Preparation Example 1 of the colorant dispersion except that 20 parts by mass of the pigment “CI Pigment Yellow 74” was used instead of 20 parts by mass of the carbon black. A particle dispersion (hereinafter referred to as “colorant dispersion (2)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (2) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm. there were.

(Preparation of colorant dispersion (3))
In the colorant dispersion (1), the same procedure as in Preparation Example 1 of the colorant dispersion was performed except that 20 parts by mass of quinacridone-based magenta pigment “CI Pigment Red 122” was used instead of 20 parts by mass of carbon black. A dispersion of colorant particles (hereinafter referred to as “colorant dispersion (3)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (3) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm. there were.

(Preparation of colorant dispersion (4))
In the colorant dispersion liquid (1), except that 20 parts by mass of phthalocyanine cyan pigment “CI Pigment Blue 15: 3” was used instead of 20 parts by mass of carbon black, Similarly, a dispersion of colorant particles (hereinafter referred to as “colorant dispersion (4)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (4) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 120 nm. there were.

(Preparation of colored particles (K1))
1250 parts by mass of latex (1) (solid content) in a reaction vessel (four-necked flask) equipped with a temperature sensor, cooling pipe, stirring device (having two stirring blades, crossing angle 20 °), and shape monitoring device Conversion), 2000 parts by mass of ion-exchanged water, and the total amount of the colorant dispersion (1) were prepared, and the internal temperature was adjusted to 25 ° C. Then, a 5 mol / liter sodium hydroxide aqueous solution was added to the dispersion mixture. The pH was adjusted to 10.0. Next, an aqueous solution in which 52.6 parts by mass of magnesium chloride hexahydrate was dissolved in 72 parts by mass of ion-exchanged water was added over 10 minutes at 25 ° C. with stirring. Thereafter, the temperature increase was started immediately, and the system was heated to 95 ° C. over 5 minutes (temperature increase rate: 14 ° C./min).

  In this state, the particle size of the associated particles was measured with “Multisizer 3” (manufactured by Coulter), and when the volume-based median diameter reached 6.5 μm, 115 parts by mass of sodium chloride was added to 700 parts by mass of ion-exchanged water. After stopping the particle growth by adding an aqueous solution dissolved in the solution, and further heating and stirring at a liquid temperature of 90 ° C. for 8 hours (stirring rotation speed 120 rpm), the fusion is continued and the aging treatment is performed. The system was cooled to 30 ° C. at 10 ° C./min, hydrochloric acid was added to adjust the pH to 3.0, and stirring was stopped.

  The produced particles are filtered, washed repeatedly with ion-exchanged water, classified in liquid using a centrifugal separator, and then dried using a flash jet dryer to obtain a “colored particle (K1) having a water content of 1.0%. "

(Preparation of colored particles (Y1))
“Colored particles (Y1)” were obtained in the same manner except that the entire amount of the colorant dispersion (1) was used instead of the entire amount of the colorant dispersion (1).

(Preparation of colored particles (M1))
“Colored particles (M1)” were obtained in the same manner except that the whole amount of the colorant dispersion (1) was used instead of the whole amount of the colorant dispersion (1) in the color particles (K1).

(Preparation of colored particles (C1))
“Colored particles (C1)” were obtained in the same manner except that the whole amount of the colorant dispersion (1) was used instead of the whole amount of the colorant dispersion (1).

(Preparation of negatively charged black toner)
0.8 parts by mass of hydrophobic silica (number average primary particle size = 12 nm, hydrophobicity = 65) and hydrophobic titania (number average primary particle size = 30 nm, hydrophobicity = 55) was added and mixed with a Henschel mixer to prepare a negatively charged negatively charged black toner.

(Preparation of negatively charged yellow toner)
A “negatively charged yellow toner” was prepared in the same manner as in the preparation of the negatively charged black toner, except that the colored particles (K1) were changed to the colored particles (Y1).

(Preparation of negatively charged magenta toner)
A “negatively charged magenta toner” was prepared in the same manner as in the preparation of the negatively charged black toner, except that the colored particles (K1) were changed to the colored particles (M1).

(Preparation of negatively charged cyan toner)
A “negatively charged cyan toner” was prepared in the same manner except that the colored particles (K1) were changed to colored particles (C1) in the production of the negatively charged black toner.

<Preparation of positively charged toner>
(Preparation of positively charged cyan toner)
(Production of colored particles (1))
Production of Resin Particles as Raw Material for Colored Particles In a flask equipped with a stirrer, 96.0 parts by mass of a release agent (Exemplary Compound (19)) is added to a mixture of the following polymerizable monomers, and 80 Warmed to ° C and dissolved. This is designated as “polymerizable monomer solution 1”.

(Polymerizable monomer solution 1)
Styrene 172.9 parts by mass n-butyl acrylate 55.0 parts by mass Methacrylic acid 23.1 parts by mass On the other hand, in a separable flask equipped with a stirrer, a temperature sensor, and a condenser tube, an anionic surfactant (101) 2. 5 parts by mass was dissolved in 1340 parts by mass of ion-exchanged water to prepare a surfactant solution. After heating the surfactant solution to 80 ° C., 2 “polymerizable monomer solution 1” was obtained using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. An emulsified liquid (dispersed liquid) containing emulsified particles (oil droplets) having a dispersed particle diameter (482 nm) was prepared by mixing and dispersing for a time.

  Next, after adding 1460 parts by mass of ion-exchanged water, an initiator solution in which 7.5 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 142 parts by mass of ion-exchanged water, and n-octanethiol 6. 74 parts by mass was added, and this system was heated and stirred at 80 ° C. for 3 hours to perform polymerization (first stage polymerization) to obtain resin particles (a dispersion of high molecular weight resin particles). This is designated as “resin particles (1)”.

  To this was added an initiator solution in which 11.6 parts by mass of a polymerization initiator (KPS) was dissolved in 220 parts by mass of ion-exchanged water, and then under the temperature condition of 80 ° C., the following “polymerizable monomer” Solution 2 "was added dropwise over 1 hour.

(Polymerizable monomer solution 2)
Styrene 291.2 parts by mass n-butyl acrylate 132.2 parts by mass Methacrylic acid 42.9 parts by mass n-octanethiol 7.51 parts by mass After completion of dropping, polymerization is performed by heating and stirring for 2 hours (second stage polymerization) Then, the mixture was cooled to 28 ° C. to obtain a dispersion of “resin particles (2)” using “resin particles (1)” as a raw material.

(Aggregating step of colored particles (1))
Aggregation of “colorant particles C” and “resin particles (2)” was performed using the following “colorant particle dispersion C” and the dispersion of “resin particles (2)”.

(Preparation of colorant particle dispersion C)
59.0 parts by mass of the anionic surfactant (101) was dissolved in 1600 parts by mass of ion-exchanged water while stirring the cyan pigment C.I. I. Pigment Blue 15: 1 280.0 parts by mass was gradually added, and then dispersion treatment was performed using “CLEARMIX” (manufactured by M Technique Co., Ltd.) to prepare “Colorant Particle Dispersion Liquid C”. The particle diameter of the colored particles in this dispersion was 93 nm.

(Aggregation process)
“Resin particles (2)” 259.3 parts by mass (in terms of solid content), 1120 parts by mass of ion-exchanged water, and 237 parts by mass of the above “colorant particle dispersion C” were combined with a temperature sensor, a cooling tube, nitrogen The mixture was stirred in a four-necked flask equipped with an introduction device and a stirring device. After adjusting the temperature in the container to 30 ° C., the pH was adjusted to 10 by adding a 5 mol / liter sodium hydroxide aqueous solution.

  Next, an aqueous solution in which 55.3 parts by mass of magnesium chloride hexahydrate was dissolved in 55.3 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 90 ° C. over 60 minutes, and “resin particles (2)” and “colorant particles C” were aggregated.

  While continuing stirring and heating, the particle size of “colored particles (1)” was measured with Multisizer 3 (manufactured by Coulter), and when the volume average particle size became 5.5 μm, sodium chloride 15.3 An aqueous solution in which part by mass was dissolved in 100 parts by mass of ion-exchanged water was added to suppress particle growth, and a “dispersion of colored particles C” was obtained.

(Solid-liquid separation, washing process)
The “dispersion of the colored particles C” was subjected to a centrifugal dehydrator, and then washed while sprinkling 50 times the amount of ion-exchanged water with respect to the solid content to obtain “toner cake C”.

(Cationic surfactant treatment process)
20 parts by weight of “Toner Cake C” was dispersed in 100 parts by weight of a 1% by weight aqueous solution in which the cationic surfactant stearyltrimethylammonium chloride was dissolved, and the mixture was stirred for 1 hour. A particle dispersion C "was obtained.

(Solid-liquid separation, drying process)
The “dispersion C of colored particles treated with a cationic surfactant” is again applied to a centrifugal dehydrator, and then washed with sprinkling 25 times the amount of ion-exchanged water with respect to the solid content. “Colored particles C” were obtained by drying with wind.

(External additive mixing process)
0.8 parts by mass of hydrophobic silica “R805” (manufactured by Nippon Aerosil Co., Ltd.) is added to 100 parts by mass of the above “colored particle C”, and the circumference of the rotor blade of “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.) The speed was set to 30 m / sec and mixed for 25 minutes. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to prepare “positively charged cyan toner” composed of “colored particles C”.

(Preparation of positively charged magenta toner)
Cyan pigment used in preparation of “positively charged cyan toner” C.I. I. Pigment Blue 15: 1, 280.0 parts by mass, magenta pigment C.I. I. “Positively charged magenta toner” was prepared in the same manner except that Pigment Red 184 was changed to 420 parts by mass.

(Preparation of positively charged yellow toner)
Cyan pigment used in preparation of “positively charged cyan toner” C.I. I. Pigment Blue 15: 1, 280.0 parts by mass, yellow pigment C.I. I. “Positively charged yellow toner” was prepared in the same manner except that Pigment Yellow 74 was changed to 420 parts by mass.

(Preparation of positively charged black toner)
Cyan pigment used in preparation of “positively charged cyan toner” C.I. I. A “positively charged black toner” was prepared in the same manner except that Pigment Blue 15: 1, 280.0 parts by mass was changed to 420 parts by mass of neutral carbon black “Regal 660” (manufactured by Cabot).

<Preparation of developing device>
The discharging member and the developing roller manufactured as described above, the negatively charged toner and the positively charged toner are sequentially mounted and filled in the developing device (the voltage applied to the developing roller and the discharging sheet is adjusted to the same potential) shown in FIG. 1-9 "were prepared.

  Table 2 shows the charge eliminating members loaded in the “developing devices 1 to 9” and the filled toner.

<Evaluation of developing device>
Evaluation of the developing device was performed by sequentially mounting the developing device prepared above on a color laser printer “magiccolor 2430DL (manufactured by Konica Minolta Business Technologies)” and printing in a normal temperature and normal humidity (20 ° C., 55% RH) environment. .

  The initial performance evaluation of the developing device was to print a single A4 size document with a pixel rate of 20% (full color mode with 5% each color of yellow, magenta, cyan, and black), its toner image quality (image density), and development position. The toner charge amount at 1 and the toner charge amount at the charge removal position were evaluated.

  Thereafter, 5000 sheets were printed using a document having an image rate of 4% (a full color mode of 1% of each color of yellow, magenta, cyan, and black).

  The performance evaluation after printing 5000 sheets was done by printing one A4 size original with a pixel rate of 20% (full color mode of 5% for each color of yellow, magenta, cyan, and black) as the initial performance evaluation, and the print image quality ( The image density, fogging), the toner charge amount at the development position, the toner charge amount at the charge removal position, and the in-machine contamination state were evaluated.

<Charge amount>
The charge amount of the black toner at the development position at the beginning and at the end of printing 5000 sheets and the charge amount of the black toner after passing through the charge removal sheet (charge removal position) were measured by the above-described measurement methods.

  The charge amount is 15 to 25 μQ / g within the acceptable range.

<Image density>
The image density was evaluated by measuring the density of the solid black image portion at the initial stage and at the end of printing 5000 sheets using a reflection densitometer “RD-918 (manufactured by Macbeth)” and the average density. The density was measured using a reflection densitometer “RD-918 (manufactured by Macbeth)”.

  The initial image density is 1.3 or more and 1.20 or more after completion of 5000 sheets.

<Image cover>
The image fog was evaluated based on the difference between the fog density of the plain image after printing 5000 sheets and the white paper density of the transfer material.

  The white paper density of the transfer material is measured at 20 locations of A4 size, and the average value is defined as the white paper density. The fog density of a plain image after printing 5000 sheets is measured at 20 locations of A4 size, and the average value is defined as the fog density. The density was measured using a reflection densitometer “RD-918 (manufactured by Macbeth)”. For cover, pass and pass.

Evaluation criteria A: Image fog is less than 0.003, good ○: Image fog is 0.003 or more and less than 0.010, practically no problem ×: Image fog density is 0.010 or more, practical problem Level that becomes.

<In-flight dirt (toner spillage)>
After printing 5000 sheets, the periphery of the developing unit was visually observed, and the toner spillage around the developing unit was visually observed and evaluated. In addition, ◎ and ○ are acceptable for in-machine dirt.

Evaluation Criteria A: Toner spillage is not observed and good B: Toner spillage is slightly observed but has no practical problem ×: Toner spillage causes severe in-machine contamination and causes a practical problem.

  Table 3 shows the evaluation results.

  From the evaluation results in Table 3, it was confirmed that “Developing devices 2, 3, 5, and 9” in Examples 1 to 4 had good results in all evaluation items and exhibited the effects of the present invention. On the other hand, it was confirmed that the “developing devices 1, 4, 6-8” of Comparative Examples 1 to 5 did not give satisfactory results in any of the evaluation items and did not exhibit the effects of the present invention.

It is a schematic diagram which shows the measuring method of the surface resistance of a static elimination sheet. It is a schematic diagram which shows an example of the static elimination member by which the static elimination sheet was fixed by the pad. It is a layer structure schematic diagram showing an example of a development roller concerning the present invention. It is a block diagram explaining the measuring method of the volume resistance value of a developing roller. 1 is a schematic cross-sectional view illustrating an example of a developing device of the present invention. It is a schematic diagram showing a developing device in which the voltage applied to the developing roller and the charge removal sheet is the same potential. It is a schematic sectional drawing which shows an example of a full-color image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Developing device 25 Developing roller 26 Buffer chamber 27 Hopper 28 Restricting blade 29 Auxiliary blade 30 Supply roller 31 Rotating body 32 Passage 50 Static elimination member T Non-magnetic single component toner

Claims (2)

Means for forming a thin layer of non-magnetic one-component toner to which a charge is applied using a regulating blade on the surface of a developing roller in which a coating layer is directly provided on the outer periphery of the conductive shaft;
Means for developing and visualizing an electrostatic latent image on the surface of the photoreceptor without bringing the thin layer of the non-magnetic one-component toner into contact with the photoreceptor;
In a developing device having a means for discharging charges of the non-magnetic one-component toner remaining on the surface of the developing roller after visualization by a discharging sheet,
The charge polarity of the charge removal sheet is the same as the charge polarity of the non-magnetic one-component toner,
The developing device characterized in that the surface resistance value of the charge eliminating sheet is 1 × 10 ¹⁰ to 1 × 10 ¹⁶ Ω · cm. 2. The developing device according to claim 1, wherein in the developing device, voltages applied to the developing roller and the charge eliminating sheet are the same potential.

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