JP2009186862A - Development device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device suppressing or preventing the disturbance of the conveyance of toner due to the aggregation of the toner on a conveying body or the like by effectively suppressing the aggregation and blocking of the toner on the conveying body in conveying the toner by a traveling wave electric field. <P>SOLUTION: The developing device 20 includes: a developer storage body 22 storing developer containing the toner having predetermined static charge characteristics; and the conveying body 30 conveying the toner to a developing area by the traveling wave electric field. The developer contains the toner and a static eliminating agent having static charge characteristics opposite to the predetermined static charge characteristics of the toner. Such a developer is used to suppress or avoid the aggregation phenomenon and blocking phenomenon of the toner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device using a traveling wave electric field transport system, an image forming apparatus including the developing device, and a developer.

  There are various types of developing devices applied to image forming apparatuses such as copying machines, printers, and facsimiles based on electrophotography. The developing device supplies toner carried on a developer (toner) carrying member such as a developing roller to the electrostatic latent image formed on the image carrying member by electrostatic action to visualize and develop the latent image. It is. Among such developing devices, there is an apparatus that supplies an electrostatic latent image on the image carrier for development in a non-contact state with respect to the image carrier. As one of such non-contact type developing devices, for example, one using a traveling wave electric field (electric field curtain) is known (Patent Documents 1 and 2). In this method, a developer transport body having means for generating a traveling wave electric field on the surface is prepared, and charged toner is transported from the toner storage chamber to a development area facing the image carrier, and finally an image is formed. The electrostatic latent image is developed by supplying toner to the electrostatic latent image on the carrier. The transport / development method using a traveling wave electric field does not require adjustment of the toner layer thickness using a blade or the like, requires less toner to be charged by friction than other methods, and does not contact the toner without contact. It is known that there is a merit that mechanical stress on the toner can be reduced because it can be attached to the image carrier. There is also a known merit that the toner can be directly adhered to the image carrier from the conveyance body in a non-contact manner, so that a developing roller or the like is not required and torque can be suppressed.

JP 59-181371 A JP 2002-99142 A

  However, according to the present inventors, when a circulation operation is performed in which the toner is transported from the inside of the container and returned to the container by a transport method using a traveling wave electric field, the toner aggregates on the transport body. Or blocking (fixing of toner aggregates to the conveyance body), and it was found that toner conveyance is hindered. At present, no toner that can suppress or avoid such inconvenience is provided.

  Accordingly, the present invention provides a developer and a developer that can effectively suppress toner aggregation and blocking on the conveyance body when the toner is conveyed by a traveling wave electric field, thereby suppressing or avoiding toner conveyance inhibition due to such aggregation and the like. An object is to provide an apparatus and an image forming apparatus.

  In order to solve the above-mentioned problems, the present inventors have examined the above-described toner aggregation and blocking phenomenon. As a result of frictional charging between the carrier and the toner during traveling-wave electric field transportation, The inventors have found that both the toner and the transport body are excessively charged (charged up), and the toner adheres to the transport body. Furthermore, the present inventors have made various studies on the toner and other elements than the toner, and obtained the knowledge that the above aggregation phenomenon and blocking phenomenon can be suppressed or avoided by adding particles having charging characteristics opposite to those of the toner. It was. Based on these findings, the present inventors have completed the following invention.

  According to the present invention, there is provided a developing device comprising: a developer container that contains a developer containing toner having a predetermined charging characteristic; and a carrier that conveys the toner to the development region by a traveling wave electric field. A developing device is provided in which the developer contains the toner and a charge eliminating agent having a charging characteristic opposite to the predetermined charging characteristic of the toner.

  According to the developing device of the present invention, by including the charge eliminating agent in the developer together with the toner, it is possible to suppress or prevent toner aggregation and blocking on the transport body by suppressing toner adhesion on the transport body. . For this reason, the conveyance obstruction resulting from these can be suppressed or avoided and conveyance can be accelerated | stimulated.

  In the developing device of the present invention, the neutralizing agent can be a toner-like body containing at least a binder resin. By using the charge-removing agent as a toner-like body, a charge-removing agent corresponding to the toner to be used can be prepared. The neutralizing agent can have a color tone that does not hinder image formation by the toner. Preferably, it should have no color tone (that is, it does not contain a colorant). Since the neutralizing agent has such a color tone, and preferably does not have a color tone, even if the neutralizing agent accidentally lands on the image carrier together with the toner, the image is not inhibited. Moreover, it is not necessary to remove the static eliminating agent. The developer may contain 10 parts by mass or more and 70 parts by mass or less of a static elimination agent with respect to 100 parts by mass of the total amount of the toner and the static elimination agent. By containing the neutralizing agent within this range, it is possible to effectively exert the neutralizing action and obtain the conveyance promoting effect.

  In the developer, the charge eliminating agent may have a larger average particle size than the toner. Since the neutralizing agent has an average particle diameter equal to or larger than that of the toner, it is possible to effectively neutralize the charge. The average particle size of the static eliminating agent is preferably 5 μm or more and 25 μm or less. When the average particle diameter of the neutralizing agent is within this range, the effect of the neutralizing agent is easily obtained. Further, aggregation or blocking of the toner can be suppressed on the conveyance body. By having such an effect, toner conveyance can be surely promoted. The toner may have a positive charging characteristic. A toner having a positive charging characteristic is preferable in terms of environmental conservation, and is also effective for neutralizing with a neutralizing agent.

  According to the present invention, there is also provided an image forming apparatus that includes any one of the above developing devices. According to the image forming apparatus of the present invention, by providing the above-described developing device, it is possible to exhibit the operational effects of the developing device, and as a result, it is possible to provide stable toner transportability.

  In addition, according to the present invention, there is provided a developer used in a developing device including a transport body that transports toner to a development region by a traveling wave electric field, the toner having a predetermined charging characteristic, and the predetermined charging characteristic of the toner. Also provided is a developer containing a neutralizing agent having reverse charging characteristics.

  According to the developer of the present invention, since the charge eliminating agent is contained together with the toner, it is possible to suppress excessive charging due to frictional charging between the toners and between the toner and various members, which are generated due to the conveyance of the toner by the traveling wave electric field. For this reason, it is possible to suppress the toner from adhering to the conveyance body, and as a result, it is possible to suppress toner aggregation and blocking and to promote toner conveyance.

  In the developer of the present invention, various aspects already described in the developing device of the present invention can be adopted.

  The present invention relates to a developing device, an image forming apparatus, and a developer. Hereinafter, these embodiments of the present invention will be described in detail with reference to the drawings as appropriate. For convenience of explanation, the image forming apparatus, the developing apparatus, and the developer will be described in this order. FIG. 1 shows an example of the developing device of the present invention. FIG. 1 illustrates an embodiment of the present invention and does not limit the present invention.

(Image forming device)
The image forming apparatus includes an image forming unit, a fixing unit, and a paper transport unit having a developing device of the present invention described later.

  In the following description, the image forming apparatus is shown as a full-color laser printer. However, the image forming apparatus is not limited to this, and a printer other than a laser printer, a copying machine, a facsimile machine, and a multifunction machine having two or more of these functions. Any of these may be used. Further, as long as the image forming apparatus includes the developing device of the present invention, the charging method in the charging process in the electrophotographic method, the type of the light source of the exposure member used in the exposure process, the exposure method, the transfer method, and the fixing method are not particularly limited. The image forming apparatus may be full color or monochrome.

(Image forming unit)
The image forming unit 10 constitutes an electrophotographic full color image forming unit. The image forming unit 10 includes four image forming units (not shown) for yellow image, magenta image, cyan image, and black image respectively corresponding to yellow, magenta, cyan, and black. For example, the yellow image forming unit, the magenta image forming unit, the cyan image forming unit, and the black image forming unit are arranged in this order along the paper transport path from the paper supply side of the paper transport unit to the fixing unit. It is installed side by side. Each image forming unit has substantially the same configuration, and each color image forming unit forms a toner image of each color of yellow, magenta, cyan, and black based on the image data of each color, and finally Transfer on paper. In addition to the image carrier 12 and the developing device 20, each image forming unit includes a charging member (not shown), an exposure member, a transfer member, a cleaning member, and a charge eliminating member.

  The image carrier 12 is not particularly limited, but may be a drum shape having a photoconductive layer on the surface. The image carrier 12 is configured to be rotationally driven in a predetermined direction. The photoconductive layer of the image carrier 12 is charged to a predetermined potential by a charging member.

  The charging member uniformly charges the surface of the image carrier 12. Examples of the charging member include, but are not limited to, various forms such as a conductive wire such as tungsten, a metal shield plate, a corona charger including a grid plate, a charging roller, and a charging brush.

  The exposure member exposes the charged surface of the image carrier 12 based on the pixel data to form an electrostatic latent image. Image data is input to the exposure member from a controller (not shown) of the image forming apparatus, and an electrostatic latent image corresponding to image data of a specific color can be formed on the image carrier 12. ing. The exposure member is not particularly limited, and a laser scanning unit (LSU) provided with a laser irradiation unit and a reflection mirror, or an EL or LED writing head in which light emitting elements are arranged in an array, or the like is used.

  The developing device 20 develops the electrostatic latent image formed on the image carrier 12 using a developer containing toner to form a toner image (visible image). The developing device 20 and the developer will be described in detail later.

  The transfer member transfers the toner image on the image carrier 12 onto a sheet conveyed by a sheet conveyance unit described later. A bias voltage having a polarity opposite to that of the toner is applied to the surface of the transfer member. Examples of the transfer member include, but are not limited to, a corona transfer device, a transfer roller, and a transfer brush. In the image forming apparatus, the transfer member employs a direct transfer system in which the toner image formed on the image carrier 12 is directly transferred to a sheet. You can also Further, a four-cycle method may be used instead of the tandem method.

  The cleaning member removes the toner remaining on the image carrier 12 after the image is transferred to the paper. A typical example is a cleaning blade, but it is not particularly limited. The neutralizing member is disposed on the rear side of the cleaning member, and removes the potential remaining on the surface of the image carrier 12, and the form of removing the potential is not particularly limited.

(Fusing unit)
The fixing unit includes a heating roller and a pressure roller. When the paper is conveyed to these nip portions, the toner image is fixed to the paper by thermocompression. The paper after the toner image is fixed by the fixing unit is discharged to a paper discharge tray (not shown).

(Paper transport unit)
The paper transport unit includes a driving roller, a driven roller, and a transport belt, transports a paper for transferring a toner image to a transfer member of each image forming unit, and further fixes the paper on which the toner image is transferred. The sheet is conveyed to a unit and the sheet on which the toner image is fixed is discharged to a sheet discharge tray (not shown). The conveying belt is wound around a driving roller and a driven roller, and conveys a sheet supplied from a sheet tray (not shown) to each image forming unit.

(Developer)
Next, the developing device 20 will be described in detail. As shown in FIG. 1, the developing device 20 includes a developer container 22 containing toner. The container 22 is formed in a container shape having a developing opening 24 and an inclined bottom portion 26 in a region facing the image carrier 12. Inside the developer container 22, a stirring member 28 for stirring the developer inside the container 22 and a transport body 30 that transports the developer, that is, toner, are provided. The container 22 is not limited to the form illustrated in FIG. 1, and can be appropriately changed depending on the image forming method in the image forming apparatus, the installation form of the image forming unit 10 and the developing device 20, and the like.

  The agitating member 28 is provided in the vicinity of the lower end of the inclined bottom portion 26 inside the containing body 22 so that the developer returned and accumulated from the conveying body 30 to the inside of the containing body 22 can be stirred. The agitating member 28 can supply the developer to the conveyance start end 32b of the conveyance body 30 while agitating the developer. The stirring member 28 can further stir the developer and can charge the toner as a component of the developer by frictional charging. In addition, the installation form of the stirring member 28, its shape, etc. are not specifically limited. In FIG. 1, as an example, a rotary blade including a plurality of blades is described, but a screw or an auger may be used.

  The conveyance body 30 is provided to face the image carrier 12 in the developing opening 24 of the container 22. The carrier 30 includes an insulating base 32 facing the image carrier 12 and a plurality of electrode groups 34 arranged at regular intervals on the surface of the base 32 on the image carrier 12 side. The base 32 includes a substantially flat plate portion 32a that faces the image carrier 12, and a conveyance start end portion 32b that is bent from one end (left side in FIG. 1) of the opening portion 24 toward the inside of the container 22. , And a conveyance end end 32c that is bent from the other end (right side in FIG. 1) of the opening 24 toward the inside of the container 22.

  The conveyance start end portion 32 b is bent from the one end of the opening portion 24 toward the vicinity of the lower end of the bottom portion 26 of the container 22. That is, the stirrer 28 is generally directed. Therefore, the developer that is accumulated near the lower end of the bottom portion 26 of the container 22, stirred by the stirring member 28, and pushed out toward the opening 24 is easily supplied to the transport body 30. Further, the conveyance end end portion 32 c is bent at the other end of the opening portion 24 in the vicinity of the upper end of the bottom portion 26 in the container 22. For this reason, the developer returned from the transport body 30 to the inside of the container 22 is easily supplied to the stirring member 28 using the inclination of the bottom portion 26 of the container 22.

  Each electrode 36 constituting the electrode group 34 arranged on almost the entire surface of the base 32 has a linear form having a length substantially matching the width of the base 32. Each electrode 36 is arranged on the base 32 so that its long side is orthogonal to the developer transport direction. An AC power source (not shown) is connected to each electrode 36, and a traveling wave electric field is formed on the surface of the carrier 30 by applying a four-phase AC having a phase shift to each electrode 36. It can be conveyed to the development area.

(Developer)
Next, the developer used in the developing device 20 will be described. The developer contains a toner having predetermined charging characteristics. The developer may be a non-magnetic one-component system or a magnetic two-component system including a toner and a magnetic carrier. From the viewpoint of miniaturization of the developing device 20 and the image forming apparatus, a non-magnetic one-component system is preferable. In the following description, both of these two types will be described. However, the magnetic two-component developer will be supplemented as necessary.

  The toner used for the developer has predetermined charging characteristics. The charging characteristic of the toner as the image forming agent may be positively charged or negatively charged. The charging characteristics of the toner are mainly determined by the formation form of the electrostatic latent image in the image forming unit 10 and the adhesion form of the toner to the electrostatic latent image. The toner is preferably a positively charged toner from the viewpoint of environmental protection. The constituent components and production method of the toner will be described in detail later. When the developer is a magnetic two-component system, an appropriate magnetic conductive carrier is included. The carrier is typically iron or ferrite.

  The developer contains a static eliminating agent. The neutralizing agent can have a charging characteristic opposite to that of the toner. Having a charging characteristic opposite to the charging characteristic of the toner means that a charging tendency opposite to that of the toner is exhibited by friction with the toner. In other words, it means that the charging tendency in the triboelectric charging series has a tendency opposite to that of the toner. For example, when the positively chargeable toner exhibits a predetermined level of positive charging tendency in the triboelectric charging series, the neutralizing agent has a tendency in the opposite direction to the predetermined level of positive charging tendency, that is, negative charging. What shows a tendency should just be. That is, the charging characteristics exhibited by the charge eliminating agent are relative to the charging characteristics of the toner.

  When the charge eliminating agent has the above-mentioned charging characteristics in relation to the toner, it is coexisted with the toner in the developing device 20, thereby causing excessive charging (charging up) due to frictional charging between the toners due to friction with the toner. It can be effectively suppressed or avoided. For this reason, in the conveyance body 30, toner aggregation or blocking is effectively suppressed or avoided, and the developer can be smoothly conveyed.

  It is preferable that the static eliminating agent has a charging tendency opposite to that of any of these charging characteristics when compared with the charging characteristics of the base body 32 and the stirring member 28 of the carrier 30. When the charge eliminating agent exhibits such a charging tendency, it is possible to effectively suppress or avoid such charge-up due to friction between the toner and the substrate 32 and the stirring member 28. For this reason, toner aggregation and blocking in the conveyance body 30 can be effectively suppressed or avoided.

  The neutralizing agent is not particularly limited as long as it has the above-described charging characteristics, and its material, configuration, shape, size, and the like are not particularly limited. A person skilled in the art can appropriately determine the material in consideration of the charging characteristics of the toner.

  The neutralizing agent of the present invention does not include a carrier in a magnetic two-component developer. The carrier in the magnetic two-component developer and the charge eliminating agent in the present invention can be distinguished from each other in that the charge eliminating agent in the present invention does not have magnetism.

  Since the neutralizing agent itself is triboelectrically charged with the toner, it is preferably itself a particulate. Note that the neutralizing agent may not exist as primary particles throughout the transport process, and may form secondary particles together with the toner to form a developer, or form secondary particles between the neutralizing agents. You may do it.

  The neutralizing agent may be particles containing at least a binder resin. Here, the binder resin means a resin having a binder performance itself. Further, the neutralizing agent may be toner base particles (toner-like body) of toner including at least a binder resin. Note that the toner-like body in the charge eliminating agent may or may not contain a colorant for image formation, and may or may not contain a wax for fixing. A colorant may be contained for imparting an appropriate color tone. By using the charge-removing agent as a toner-like body, it is possible to obtain the charge-removing agent as easily as (or simultaneously with) the toner. Also, charging characteristics and the like can be easily controlled. When the charge-removing agent is a toner-like body, it can be a toner-like body containing an additive to such an extent that a predetermined charging characteristic can be imparted if necessary. In order to impart the necessary charge characteristics to the charge eliminating agent, one or both of a charge control agent and an external additive used in normal toner production may be added to the toner base particles as necessary. . When the charge eliminating agent is a toner-like body, the toner base particles containing the binder resin may be shared with the toner base particles of the toner as the image forming agent, and only the charging characteristics may be different. By using a charge control agent or an external additive to be used having a charge characteristic opposite to that of the toner, the charge eliminating agent can be easily produced.

  The neutralizing agent is preferably adjusted so as to have a color tone that does not hinder image formation by the toner when applied to the paper together with the toner. Since the charge eliminating agent has a charging characteristic opposite to that of the toner, it is not supplied to the image carrier 12 in the same manner as the toner, but if it is adjusted to the above color tone, it is erroneously supplied to the image carrier 12. This is because even when it is done, image formation is not hindered. For example, the neutralizing agent can be provided with no colorant and little or no color tone. For example, it can be colorless or nearly colorless. Further, the neutralizing agent can be the same color or the same color as the toner. For example, in the case of cyan toner, the saturation and brightness may be similar to those of the toner, or may be lower or higher than the toner in terms of brightness and / or saturation. An appropriate color tone in the static elimination agent can be easily obtained by appropriately changing the amount (presence / absence) of the colorant to be used and the type of the colorant to be used as necessary. It is most preferable that the static eliminating agent does not contain a colorant and is transparent per se.

  Note that “not hindering image formation by toner” means that an unintended defect is not at least explicitly given to the toner image by the charge eliminating agent. When such a defect is explicitly given, it cannot be said that it does not hinder image formation with toner. Here, “explicit” means being visually recognized. The type of defect is not particularly limited, and examples thereof include a decrease in image resolution such as color unevenness and blurring.

  The neutralizing agent is preferably spherical in consideration of the contact area with the toner, the carrier 30 and the stirring member 28, fluidity, mixing uniformity with the toner, and the like. More preferably, it is a spherical shape. In view of durability, a solid body is preferable to a shell.

  The size of the static eliminating agent is not particularly limited. It may be determined appropriately in consideration of the uniformity of mixing with the toner. Considering the toner aggregation or blocking inhibiting effect, the average particle size of the charge eliminating agent is preferably equal to or larger than the average particle size of the toner. The average particle size of the neutralizing agent is preferably 50% or more and 400% or less with respect to the average particle size of the toner. If it is this range, it can discharge efficiently.

  Moreover, it is preferable that the average particle diameter of a static elimination agent is 5 micrometers or more and 25 micrometers or less. Within this range, the toner having an average particle size of 5 μm or more and 25 μm or less can be effectively neutralized. The average particle diameter of the static eliminating agent is more preferably 10 μm or more and 25 μm or less.

  In addition, about the average particle diameter of a toner and a static elimination agent, the measuring method by a pore electrical resistance method is employable. Further, in this measurement method, it is preferable to measure the volume average particle size using a Beckman Coulter Coalter Multisizer II (aperture diameter 100 μm) or an equivalent device. When comparing the average particle size of the toner and the charge eliminating agent, it is preferable to use the average particle size and particle size measured by the same average particle size measurement method.

  One type of such a static eliminating agent may be used, or two or more types may be used in combination. When two or more types of static eliminating agents are used, any combination may be used. Any of the material, particle structure, shape, size, charging characteristics, etc. of the neutralizing agent, or two or more of these may be different.

  The content of the static eliminating agent in the developer is not particularly limited. The developer can contain the neutralizing agent to such an extent that the aggregation of the toner or blocking can be suppressed by the action of the neutralizing agent to prevent or avoid the conveyance of the developer. Normally, if the developer contains a static eliminating agent, a significant developer transport promoting effect can be obtained by the static eliminating effect. Preferably, in the developer, the charge removal agent is 10 parts by weight or more and 70 parts by weight or less with respect to 100 parts by weight of the total amount of toner and charge removal agent (hereinafter simply referred to as the total amount). By containing 10 parts by mass or more and 70 parts by mass or less of the charge eliminating agent with respect to 100 parts by mass in total, it is possible to dramatically improve the inhibitory effect or avoidance effect (conveying promotion effect) of developer conveyance. More preferably, it is 30 parts by mass or more. When the amount is 30 parts by mass or more, it is easy to obtain a conveyance promotion effect that is 7 times or more compared to the case where the neutralizing agent is not included. More preferably, it is 40 parts by mass or more. When it is 40 parts by mass or more, it is easy to obtain a conveyance promoting effect that is 10 times or more compared with the case where the neutralizing agent is not included. Moreover, it is preferable that a static elimination agent is 70 mass parts or less. This is because even if it is added in excess of 70 parts by mass, it is difficult to obtain a dramatic effect of promoting transportation. More preferably, it is 60 parts by mass or less. From the above, the range of the more preferable blending ratio of the static eliminating agent is 40 parts by mass or more and 60 parts by mass or less, more preferably 45 parts by mass or more and 55 parts by mass or less, and 50 parts by mass with respect to the total amount of 100 parts by mass. Most preferred are parts.

  In addition, the conveyance promotion effect when using a static elimination agent can use the continuous conveyance time in the evaluation system described in the Example as a parameter | index, for example.

  The developer can be obtained by mixing a toner together with the above-described static eliminator and, if necessary, a magnetic carrier. The mixing method is not particularly limited, and a method usually used for this type of developer can be employed. In addition to the essential components in the developer such as a toner, a static eliminator, and a carrier, the developer can contain known additives as appropriate.

  Next, a process of applying the developer to the developing device 20 of the image forming apparatus, transporting the toner, and developing the toner will be described. In the following example, a toner image forming operation corresponding to the image information related to the image forming command on the sheet is started in the image forming apparatus based on the image forming command from the PC terminal connected via the LAN or the like. The developing process will be described.

  When a controller (not shown) of the image forming apparatus receives an image forming command via the LAN via the interface, the controller performs color separation into each color based on image information related to the image forming command, and yellow, magenta, cyan, and black The image information of each color is generated.

  Next, the following operations are executed in each image forming unit. First, the entire surface of the image carrier 12 is charged by the charging member, and the exposure member is exposed to the image carrier 12 in accordance with the image information of each color to form an electrostatic latent image.

  At the same time as or before the formation of the electrostatic latent image, the developing device 20 starts preparation of a developer for development. That is, the rotation of the stirring member 28 in the container 22 is started, and stirring of the developer stored in the container 22 is started. By such stirring, the toner in the developer is charged by frictional charging with the stirring member 28 or the like or by frictional charging between the toners. On the other hand, when the charge eliminating agent coexists with the toner, excessive charging of the toner is suppressed due to frictional charging between the toner and the charge eliminating agent.

  Further, in the developing device 20, a four-phase alternating current having a predetermined amount of phase shift is applied to each electrode 36 of the electrode group 34 arranged on the base 32 of the transport body 30, and proceeds to the surface of the transport body 30. A wave electric field is formed. As a result, the developer, particularly the toner in the developer, which is in the container 22 of the developing device 20 and rides on the transport body 30 from the transport start end 32b of the base body 32, travels between the electrodes 36. It is transported while moving. At this time, since the charge eliminating agent coexists in the developer, excessive charging due to frictional charging between the substrate 32 and the toner and frictional charging between the toners is suppressed or avoided. That is, the toner and the conveyance body 30 are suppressed from being excessively charged to opposite polarities, and the toner is prevented from adhering to the conveyance body 30. That is, aggregation and blocking of the toner on the conveyance body 30 are suppressed, and conveyance inhibition due to such aggregation or the like is suppressed or avoided (conveyance is promoted).

  Next, when the electrostatic latent image on the image carrier 12 reaches an area (development area) facing the developing device 20 by the rotation of the image carrier 12, the electrostatic latent image is arranged on the substrate 32 of the conveyance body 30 of the developing device 20. The toner contacts with the toner conveyed by the traveling wave electric field action on the electrode group 34, and the toner lands on the electrostatic latent image on the image carrier 12 by the clonal force. As a result, a toner image corresponding to the electrostatic latent image is formed on the image carrier 12. Note that the toner may be attached in a form in which the toner is pushed into a region where the charge has been removed by exposure, or in a form in which the toner is attached in a region where the charge remains by exposure.

  When the toner is transported by the traveling wave electric field action, it is landed even if the transport body 30 is not in contact with the image carrier 12, so that the load on the toner due to contact with the image carrier 12 and the image carrier Twelve loads are reduced. Further, the carrier 30 is landed even when the image carrier 12 is not in contact with the image carrier 12. As a result, a toner image corresponding to the electrostatic latent image is formed on the image carrier 12.

  After the toner image is formed on the image carrier 12, when the toner image reaches the transfer member 40 by the rotation of the image carrier 12, the toner image is formed on the paper supplied to the transfer member 40.

  The sheets are sequentially conveyed in the order of the image forming units for the respective colors, and toner images of the respective colors are formed on the sheet in this order.

  As described above, according to the developing device 20 that accommodates the developer of the present invention, the developer contains the neutralizer together with the toner, so that the charged toner is transported by the traveling wave electric field and the toner in the container 22 is contained. During the stirring, excessive charging of the toner and the conveyance body 30 can be prevented. Thereby, aggregation and blocking of the toner on the conveyance body 30 can be effectively suppressed or avoided. As a result, the conveyance of the toner can be promoted, and the toner can be conveyed continuously for a longer time. become.

  In the above description, the developing device 20 has been described as corresponding to a tandem full-color laser printer. However, the developing device of the present invention is not limited to this, and the various types of aspects described above can be used. It can be configured to correspond to an image forming apparatus. In the above description, the developing device 20 has not been provided with the image carrier 12, that is, a separation type developing device. However, the developing device of the present invention is not limited to this, and the image carrier is not limited thereto. An integral type including the body 12 as a developing device may be used.

  In the above description, the developer manufacturing method is not described. However, according to the description of the toner and the manufacturing method described in detail later, the present invention can also be implemented as a developer manufacturing method. it can.

  Hereinafter, a toner that is an essential component of the developer and a method for producing the toner will be described. As described above, in the case where the charge-removing agent is a toner-like body, the following toner and its manufacturing method are applied to the charge-removing agent as a toner-like body and its manufacturing method. As a method for producing the toner, a known method can be applied in addition to those described below. Examples thereof include a kneading and pulverizing method, a dissolution suspension method, a suspension polymerization method, an emulsion polymerization method, and an emulsion aggregation method.

(toner)
The toner has a binder resin, a colorant, a wax, and a charge control agent. The neutralizing agent has a binder resin, a wax, and a charge control resin, and does not contain a colorant. Moreover, an external additive is added as needed.

  The binder resin is not particularly limited, and a known synthetic resin known as a toner binder resin is used. For example, polyester resins, styrenic resins (for example, styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene, and derivatives thereof, such as styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, etc. Styrene-styrene derivative copolymer, for example, styrene-vinyl naphthalene copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene- Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Inden Styrene copolymers such as polymers), acrylic resins, methacrylic resins, polyvinyl chloride resins, phenol resins, natural modified phenolic resins, natural resin modified maleic acid resins, polyvinyl acetate, silicone resins, polyurethane resins, polyamide resins , Furan resin, epoxy resin, polyvinyl butyral resin, terpene resin, coumarone indene resin, petroleum resin and the like. These can be used alone or in combination.

(Coloring agent)
The colorant imparts a desired color to the toner and is dispersed or penetrated into the binder resin. Examples of the colorant include carbon black such as quinophthalone yellow, hansa yellow, isoindolinone yellow, benzidine yellow, perinone olein, perinone red, perylene maroon, rhodamine 6G lake, quinacridone red, rose bengal, copper phthalocyanine blue, copper phthalocyanine green. Organic pigments such as diketopyrrolopyrrole pigments such as titanium white, titanium yellow, ultramarine blue, cobalt blue, brown, aluminum powder, bronze and other inorganic pigments or metal powders such as azo dyes, quinophthalone dyes, anthraquinones Oil-soluble or disperse dyes such as dyes, xanthene dyes, triphenylmethane dyes, phthalocyanine dyes, indophenol dyes, indoaniline dyes, etc. If, rosin, rosin-modified phenol, rosin-based dyes such as rosin-modified maleic acid resins. Furthermore, dyes and pigments processed with higher fatty acids and resins are also included.

  These can be used alone or in combination depending on the desired color. For example, a chromatic single color toner can be blended with pigments and dyes of the same color, for example, rhodamine pigments and dyes, quinophthalone pigments and dyes, and phthalocyanine pigments and dyes. The colorant is blended in an amount of, for example, 2 to 20 parts by mass, preferably 4 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

(wax)
Wax is added to improve the fixability of the toner to the recording medium. In the case of the heating pressure fixing method, it is common to enclose wax inside the toner so that the toner is easily peeled off from the heating medium. Examples of the wax include ester wax and hydrocarbon wax.
Examples of the ester wax include aliphatic ester compounds such as stearic acid esters and palmitic acid esters, for example, polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, and dipentaerythritol hexapalmitate. Can be mentioned.
Examples of hydrocarbon waxes include polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene, such as plant natural waxes such as candelilla, carnauba, rice, wood wax, jojoba, and the like, for example, paraffin wax. And petroleum waxes such as microcrystalline and petrolatum, and modified waxes thereof, for example, synthetic waxes such as Fischer-Tropsch wax.

These waxes can be used alone or in combination. Preferably, among the waxes described above, a wax having a melting point of 50 to 100 ° C. is used. The wax having a low melting point and a low melt viscosity can prevent offset even when the heating temperature of the fixing device is low, by melting before the binder resin and exuding on the toner surface. More specifically, ester wax and paraffin wax may be mentioned.
The wax is blended in an amount of, for example, 1 to 30 parts by mass, preferably 3 to 15 parts by mass with respect to 100 parts by mass of the binder resin.

(Charge control agent)
The charge control agent is used alone or in combination from a positively chargeable charge control agent or a negatively chargeable charge control agent according to the purpose and application. As the toner and the charge eliminating agent as the toner-like body in the developer of the present invention, either or both of a positively chargeable charge control agent and a negatively chargeable charge control agent can be used. By using a combination of charge control agents having different chargeability, the chargeability can be easily adjusted, which is convenient for obtaining the developer toner and the charge eliminating agent of the present invention.
Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium compounds, onium compounds, triphenylmethane compounds, basic group-containing compounds, and tertiary amino group-containing acrylic resins. Examples of the negatively chargeable charge control agent include trimethylethane dyes, azo pigments, copper phthalocyanine, salicylic acid metal complex salts, benzyl acid metal complex salts, perylene, quinacridone, and metal complex azo dyes. The charge control agent is blended, for example, at a ratio of 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin.

(External additive)
The external additive is added to adjust the chargeability, fluidity, storage stability, and the like of the toner, and is composed of ultrafine particles having a particle size much smaller than that of the toner base particles. The toner in the developer of the present invention may be given a predetermined charging characteristic by an external additive. Similarly, in the toner-like neutralizing agent in the developer of the present invention, a charging characteristic opposite to that of the toner may be imparted by an external additive.

Examples of the external additive include inorganic particles and synthetic resin particles.
Examples of the inorganic particles include silica, aluminum oxide, titanium oxide, silicon aluminum co-oxide, silicon titanium co-oxide, and hydrophobized products thereof. For example, a hydrophobized silica product can be obtained by treating silica fine powder with silicone oil or a silane coupling agent (for example, dichlorodimethylsilane, hexamethyldisilazane, tetramethyldisilazane, etc.). it can.

  In addition, those described above are negatively charged, but as positively charged, aminosilane-silicone oil, aminoammonium-silicone oil, aminosilane hexamethyldisilazane, aminoammonium hexamethyldisilazane, aminosilane dichloro Examples thereof include dimethylsilane, aminoammonium aminosilane dichlorodimethylsilane, aminosilane polydimethylsiloxane, and aminoammonium polydimethylsiloxane.

  Synthetic resin particles include, for example, methacrylic acid ester polymer particles, acrylic acid ester polymer particles, styrene-methacrylic acid ester copolymer particles, styrene-acrylic acid ester copolymer particles, a core having a styrene polymer, and a shell. Examples thereof include core-shell type particles made of a methacrylic acid ester polymer.

  In the addition of the external additive, for example, the toner base particles and the external additive are stirred and mixed using a high-speed stirrer such as a Henschel mixer. The external additive is usually added at a ratio of 0.1 to 6 parts by mass with respect to 100 parts by mass of the toner base particles.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited to a following example.

[Toner preparation]
The following raw materials were mixed and then heated to 45 ° C. to prepare a resin solution.
Polyester resin FC1565 * 1 17 parts by weight Ester wax * 2 1 part by weight Nigrosine dye (charge control agent) * 3 1 part by weight Carbon black (colorant) * 4 1 part by weight Methyl ethyl ketone 80 parts by weight * 1 Mitsubishi Rayon Co., Ltd. Manufactured, Tg 64 ° C., Mn (number average molecular weight) 5000, Mw (weight average molecular weight) 98000, gel content (THF insoluble matter) 1.5 mass%, acid value 6.1 mgKOH / g
* 2 NOF Corporation Unistar H476
* 3 Orient Chemical Industry Co., Ltd. Bontron NO4
* 4 Carbon black # 260 manufactured by Mitsubishi Chemical Corporation

  An aqueous medium was prepared by mixing 100 parts by mass of distilled water and 1 part by mass of a 1N aqueous sodium hydroxide solution, and then heated to 45 ° C.

  100 parts by mass of the resin solution and 100 parts by mass of the aqueous medium were blended while being maintained at 45 ° C., and then stirred with a homogenizer DIAX 900 (Haidorf Japan) at 16000 rpm for 30 minutes to prepare an emulsion.

  1600 parts by mass of the obtained emulsified liquid was inserted into a 2 L separable flask, and the organic solvent was removed by heating and stirring at 70 ° C. for 150 minutes while feeding nitrogen into the gas phase. Obtained. The volume average diameter of the resin fine particles in the suspension was 256 nm. Moreover, when the presence or absence of the precipitate in the suspension was confirmed, no precipitate was found. After the loss, the suspension was diluted with distilled water to a solid content concentration of 10% by mass to prepare 1600 parts of the suspension.

  Add 2.5 parts by weight of 0.2N aluminum chloride to 100 parts by weight of the suspension, mix at high speed for 10 minutes with a homogenizer, and then stir the suspension at 300 rpm with 6 flat plate turbine blades. While raising the temperature to 45 ° C., stirring was continued for 20 minutes. Thereafter, 2.5 parts by weight of a 0.2N aqueous sodium hydroxide solution was added to the suspension, the temperature was raised to 90 ° C., and stirring was continued for about 5 hours until the toner base particles became spherical. Then it was cooled. After cooling, 2.5 parts by mass of a 1N aqueous hydrochloric acid solution is added to 100 parts by mass of the suspension, and the mixture is stirred for 1 hour so that the suspension can flow, filtered, and dried to obtain toner base particles. Got.

  To 100 parts by mass of the obtained toner base particles, 2.0 parts by mass of silica (manufactured by Teika Co., Ltd., MSP-013 (positive charge imparting property)) is stirred and mixed using a Henschel mixer, and the positively chargeable toner particles are mixed. Got. The volume average particle diameter was measured with a Coulter Multisizer II (aperture diameter 100 μm) manufactured by Beckman Coulter.

[Preparation of static eliminating agent]
Use a resin solution having the following composition that does not contain carbon black as a raw material, and use a half amount (1.25 parts by mass) of a 0.2N aqueous sodium hydroxide solution as an aggregation terminator. Except for these two points, toner mother particles were obtained in the same manner as in the preparation of the toner described in Example 1. To 100 parts by mass of the base particles, 2.0 parts by mass of silica (manufactured by Teika Co., Ltd., MSN-007 (negative charge imparting property)) was stirred and mixed using a Henschel mixer to obtain negatively charged toner particles. The charge-removing agent was 1. The volume average particle size of the obtained toner (measured in the same manner as in Example 1) was 20 μm, and the resin solution was heated to 45 ° C. after mixing the following raw materials. The same raw materials as in Example 1 were used.

Polyester resin FC1565 18 parts by weight Ester wax 1 part by weight Nigrosine dye (charge control agent) 1 part by weight Methyl ethyl ketone 80 parts by weight

  Toner base particles are obtained by operating in the same manner as in the toner base particle preparation method described in Example 1. Further, 2.0 parts by mass of silica (MSN-007, manufactured by Teika Co., Ltd.) is added to 100 parts by mass of the toner base particles. (Negative charge imparting property) was stirred and mixed using a Henschel mixer to obtain negatively chargeable toner particles, which were used as a charge eliminating agent 2. The volume average particle diameter of the obtained toner (same as in Example 1). (Measurement method) was 7.9 μm.

[Preparation of developer]
To the toner obtained in Example 1, the neutralizing agent 1 or the neutralizing agent 2 is sufficiently mixed in a polyester bag having an appropriate capacity at a blending ratio (mass ratio) shown in the following table, and the developer 1 ~ 8 was obtained. Further, a neutralizing agent consisting only of toner was used as a comparative example.

[Developer evaluation]
Next, a certain amount of each developer obtained was supplied to the circulation experiment apparatus shown in FIG. The circulation experiment apparatus is manufactured by imitating a carrier used in a carrier system using a traveling wave electric field. Although not shown, a plurality of electrodes arranged in the transport direction are arranged inside, and four-phase alternating currents having different phases are sequentially applied to the electrodes, so that they are positively charged by the traveling wave electric field effect. The toner can be conveyed in the direction of the arrow in the figure. The transport body is set in a suitable container, and the upper surface of the transport body is covered with a transparent glass plate disposed at a certain height from the upper surface except when the developer is supplied. .

  In the evaluation, after a certain amount of each developer is supplied to the position shown in FIG. 2 at the start of the experiment, a voltage is applied in a predetermined manner and toner conveyance by a traveling wave electric field is started in the direction shown in FIG. It was confirmed whether or not the developer was circulated on the surface of the conveyance body, and the time until the circulation was not confirmed was measured to obtain a continuous conveyance time (minutes). The results are shown in FIG.

  As shown in FIG. 3, the continuous conveyance time was remarkably extended by adding negatively chargeable toner base particles as a charge eliminating agent to the positively chargeable toner base particles. Developers 1-8 were found to extend at least 2.5 times.

  In particular, in the developers 1 to 4 using the large-diameter neutralizing agent 1, the effect of extending the continuous conveyance time was higher and increased from 5 times to 15 times. Among these, in particular, when the blending ratio of the neutralizing agent to the total amount of the toner and the neutralizing agent is 30 parts by mass or more and 50 parts by mass or less, an extension effect of 7 to 15 times can be confirmed. The best extension effect was confirmed.

  Further, even in developers 5 to 8 using a small-diameter neutralizing agent 2, although the extension effect is lower than that of developers 1 to 4 using the neutralizing agent 2, the blending ratio is 30 to 50 parts by mass with respect to the total amount. In this range, a good effect was obtained, and in particular, a good effect was obtained at 50 parts by mass.

  In these examples, the binder and the colorant are not included in the preparation of the toner base particles. However, the toner base particles are prepared using the binder and the colorant, and the toner and the charge eliminating agent are prepared in the same manner. It was also confirmed that the same effect as described above was obtained.

It is a figure which shows an example of the image development apparatus of this invention. FIG. 4 is a diagram illustrating an apparatus for evaluating toner conveyance by a traveling wave electric field effect. It is a figure which shows the evaluation result of the continuous conveyance time of the developer prepared in the Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Image forming unit, 12 Image carrier, 20 Developing apparatus, 22 Container, 24 Opening part, 26 Bottom part, 28 Stirring member, 30 Conveyance body, 32 Base body, 32a Flat plate part, 32b Conveyance start end part, 32c Conveyance end end Part, 34 electrode group, 36 electrode

Claims (8)

A developing device comprising: a developer container that contains a developer containing toner having predetermined charging characteristics; and a carrier that conveys the toner to a development region by a traveling wave electric field,
The developing device, wherein the developer contains the toner and a charge eliminating agent having a charging characteristic opposite to the predetermined charging characteristic of the toner.   The developing device according to claim 1, wherein the neutralizing agent is a toner-like body containing at least a binder resin.   The developing device according to claim 2, wherein the neutralizing agent does not include a colorant.   The developing device according to claim 1, wherein the developer contains 10 parts by mass or more and 70 parts by mass or less of a static elimination agent with respect to 100 parts by mass of the total amount of the toner and the static elimination agent.   The developing device according to claim 1, wherein the neutralizing agent has an average particle diameter equal to or larger than that of the toner.   The developing device according to claim 1, wherein the neutralizing agent has an average particle diameter of 5 μm or more and 25 μm or less.   The developing device according to claim 1, wherein aggregation or blocking of the toner can be suppressed on the conveyance body.   The developing device according to claim 1, wherein the toner has a positive charging characteristic.

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