JP2006011072A - Charging device, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain electrostatic charge to an image carrier stably over a long period of time, even if a charging member is contaminated by toner and the like. <P>SOLUTION: A charging roller 20, as the charging member has resin and rubber or has a coating layer containing the resin or rubber on its surface and the coating layer, contains the component which is the same as the resin component constituting the binder resin of the toner and an electrically conductive material, and the volume resistivity of the charging roller 20 is set at 1x10<SP>3</SP>to 1x10<SP>12</SP>Ωcm. The toner remaining on a photoreceptor 1 sticks to the charging roller 20 but will stick, by having directivity in an area of high affinity where the same component as the resin component constituting the binder resin exists, and as a result thereof, the surface characteristic of the charging roller 20 is hardly changed and the charging characteristics are maintained as well. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a charging device in which a charging member is placed in contact with or close to the surface of an image carrier and charges the surface of the image carrier, a copying machine having the charging device, a printer, a facsimile, a plotter, etc. The present invention relates to an image forming apparatus and a process cartridge having the charging device.

Generally, according to the electrophotographic method, a latent image is formed on an image carrier such as a photoconductive substance, and a charged toner is attached to the electrostatic latent image to form a visible image. The formed toner visible image is finally transferred to a transfer medium (recording medium) such as paper, and then fixed on the transfer medium by heat, pressure, solvent gas, or the like to form an output image.
This electrophotographic image forming method uses a so-called two-component development method that uses friction charging generated by stirring and mixing a toner and a carrier by a method of charging a toner for visualization, and does not use a carrier. The toner is roughly classified into a so-called one-component developing system that applies charge to the toner.
The one-component development method is classified into a magnetic one-component development method and a non-magnetic one-component development method depending on whether or not a magnetic force is used for holding toner particles on the developing roller.

Conventionally, in copiers, printers, multifunction devices, etc., where high speed and image reproducibility are required, the two-component development method is used to meet the requirements for toner charging stability, start-up stability and long-term image quality stability. Many single-component development systems have been adopted for small printers, facsimiles, and the like, which are often employed and have large demands for space saving and cost reduction.
Particularly in recent years, colorization of output images has progressed, and the demand for higher image quality and stabilization of image quality has become stronger than ever.
Usually, a latent image on an image carrier is to be obtained by a latent image forming device such as a writing device using laser light after the image carrier is uniformly charged or at the same time as the image carrier is charged. It is formed as a latent image pattern corresponding to the image pattern.
In order to obtain a stable image, not only the formation of the latent image and the visualization of the latent image, that is, the stabilization of development, but also the stabilization of the image carrier for further stabilization of the image quality. It is important to maintain the above, and to suppress the variation in the charged potential depending on the location in the latent image forming portion.

To date, various proposals have been made, including corotron, scorotron, and comb-tooth electrodes.
Particularly, a charging device using corona discharge is an effective method for the uniformity of charging, and is used in many electrophotographic image forming apparatuses.
However, on the other hand, in a charging device using corona discharge, a large amount of ozone is inevitably generated due to discharge, and in order to reduce this, a contact charging method using a charging roller or a charging brush, proximity charging, or the like is used. A scheme has been proposed.
These charging devices mainly charge the image carrier using discharge in a minute area between a charging roller, a charging brush and the like and the image carrier. In such a charging device, contact / non-contact between the charging member and the photosensitive member as the image carrier is not particularly important, but in order to obtain uniform charging, the charging member and the photosensitive member are not required. It is desirable that the gap between and is small.

Therefore, in such a charging device, the charging member is generally brought into contact with or close to the surface of the photoreceptor.
In such a charging system charging device, the charging efficiency (charging potential / applied voltage) depends on the surface state of the charging member that is in contact with or close to it, and is represented by the residual toner that has not been transferred from the image carrier to the transfer medium. The time-dependent fluctuations due to cumulative adhesion / adhesion and fusion of contaminants to the charging member, and the charging efficiency at places where adhesion / adhesion / fusion have occurred and where they have not occurred Differences sometimes occurred.
When such a situation occurs, the charging efficiency of a constant voltage control charging device decreases, and the charging potential obtained with a constant applied voltage decreases. Therefore, the image density decreases and other charging potentials are controlled as reference values. Process control may not be performed properly.

  In order to solve these problems, conventionally, a so-called cleaning device that removes toner remaining on the image bearing member, a device / mechanism that cleans the charging member, and the like have been installed, and a proposal for suppressing contamination of the charging member has been proposed. Has been made.

Japanese Patent Laid-Open No. 06-266206 JP-A-10-307455 JP 2001-117319 A JP-A-10-198078

However, in the trend of demanding higher quality images, the shape of the toner is becoming more spherical and the particle size is becoming smaller. Such toner is difficult to remove by a cleaning device, and the charging member is more easily contaminated.
In other words, in the past, the degree of contamination of the charging member due to residual toner or the like in the charging device depends on the cleaning function of the cleaning device, and there was no problem if the cleaning device function could be maintained to some extent. As a result, even if the accuracy of the cleaning device is increased, the phenomenon of toner dipping occurs and contamination of the charging member cannot be avoided.
On the other hand, in order to avoid abnormalities due to contamination of the charging member as described above, some of the image carrier, charging device, developing device, etc. are integrated into a process cartridge, and the entire process cartridge is replaced every predetermined period. By doing so, the image quality is also stabilized.
However, as the momentum for environmental protection has increased recently, it has become a social mission as a manufacturer to reduce the amount of waste by reusing used process cartridges without discarding them. However, stabilization of components that can withstand long-term use, particularly stabilization of the charging device, remains a serious problem.

The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide a charging device capable of maintaining stable charging on an image carrier for a long period of time even when the charging member is contaminated with toner or the like. It is to be.
Another object of the present invention is to provide an image forming apparatus capable of obtaining a stable and high-quality image over a long period of time due to stable charging characteristics.
Another object of the present invention is to provide a process cartridge capable of stabilizing the charging device for a long period of time and reducing the environmental load.

As described above, there is a tendency for the toner to have a smaller particle size as the image quality is improved. In such a situation, extremely increasing the accuracy of the cleaning device not only increases the cost but also increases the image carrier. Therefore, the contact pressure of the cleaning member on the surface of the image bearing member must be increased, leading to early deterioration of the surface of the image bearing member (deterioration of the photosensitive layer characteristics), and a satisfactory cleaning function still cannot be obtained.
There is no need to provide a special cleaning device as long as it can tolerate a certain amount of toner contamination on the charging member and suppress changes in the charging characteristics of the charging member without depending on the cleaning function of the cleaning device. Therefore, the surface of the image carrier can be prevented from premature deterioration. The present invention has been made based on this purpose.
Specifically, in the first aspect of the invention, a charging device having a charging member that is disposed in contact with or close to the surface of the image carrier that has undergone at least a step of carrying a toner image and charges the image carrier. The charging member has a coating layer on the surface, and the coating layer has a component having affinity for the toner component forming the toner image.

  According to a second aspect of the present invention, there is provided a charging device including a charging member that is disposed in contact with or close to a surface of an image carrier that has undergone at least a toner image carrying step and charges the image carrier. A coating layer is formed on the surface of the toner, and the coating layer includes a component having an affinity for the toner component forming the toner image, and directs adhesion of the toner remaining on the image carrier to the coating layer. It is characterized by having.

  According to a third aspect of the present invention, in the charging device according to the first or second aspect, the component having affinity and the other components of the coating layer are incompatible.

  According to a fourth aspect of the present invention, in the charging device according to any one of the first to third aspects, the component having the affinity is the same as the resin component constituting the binder resin of the toner. Features.

According to a fifth aspect of the present invention, in the charging device according to any one of the first to fourth aspects, the covering layer contains an electrically conductive material, and the volume resistance of the charging member is 1 × 10 ³ Ω · cm to 1 × 10 ¹² Ω · cm.

  According to a sixth aspect of the present invention, in the charging device according to any one of the first to fifth aspects, the content of the component having affinity is 10 to 40% by weight with respect to the total amount of the coating layer. It is characterized by being.

  According to a seventh aspect of the present invention, in the charging device according to any one of the first to fifth aspects, the component having affinity is a linear polyester resin composition, a linear polyol resin composition, or linear styrene. It is characterized by being at least one of an acrylic resin composition or a cross-linked product thereof.

  According to an eighth aspect of the present invention, in the charging device according to any one of the first to fifth aspects, the charging member has a hardness measured by an Asker C hardness meter of 20 to 90 degrees.

  According to a ninth aspect of the present invention, an image carrier, a charging device for charging the image carrier, a latent image forming device for forming a latent image on the image carrier, and a latent image on the image carrier are converted into toner. An image forming apparatus having a developing device that visualizes an image, wherein the charging device is the charging device according to any one of claims 1 to 8.

  According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the charging device includes a voltage application device that applies a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage. .

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the ninth or tenth aspect, the image forming apparatus includes a plurality of image carriers, and a transfer device that superimposes and transfers the toner images on the image carriers onto a recording medium. It is characterized by.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to the ninth or tenth aspect of the present invention, a plurality of image carriers are provided, and the toner images on these image carriers are transferred onto the intermediate transfer member in an overlapping manner. And a transfer device for transferring the superimposed image onto a recording medium.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, the circularity SR of the toner represented by the following formula is 0.93 to 1.00. Features.
Circularity SR = perimeter of a circle having the same area as the particle projection area / perimeter of the particle projection image

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, the weight average diameter D4 of the toner is 3 to 10 μm.

  According to the fifteenth aspect of the invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, the ratio (D4 / D1) of the weight average diameter D4 and the number average diameter D1 of the toner is 1.00 to 1.00. It is characterized by being 1.40.

  According to a sixteenth aspect of the present invention, at least an image carrier, a charging device that charges the image carrier, a latent image forming device that forms a latent image on the image carrier, and a latent image on the image carrier. A process cartridge integrally including a developing device that visualizes a toner image, wherein the charging device is the charging device according to any one of claims 1 to 8.

According to a seventeenth aspect of the present invention, in the process cartridge according to the sixteenth aspect, the circularity SR of the toner represented by the following formula is 0.93 to 1.00.
Circularity SR = perimeter of a circle having the same area as the particle projection area / perimeter of the particle projection image

  According to an eighteenth aspect of the present invention, in the process cartridge according to the sixteenth aspect, the weight average diameter D4 of the toner is 3 to 10 μm.

  According to the nineteenth aspect of the present invention, in the process cartridge according to the sixteenth aspect, the ratio (D4 / D1) of the weight average diameter D4 and the number average diameter D1 of the toner is 1.00 to 1.40. To do.

  According to a twentieth aspect of the present invention, in the image forming apparatus detachably including a process cartridge, the process cartridge is the process cartridge according to any one of the sixteenth to nineteenth aspects.

  According to the first aspect of the present invention, in a charging device having a charging member that is arranged in contact with or close to the surface of an image carrier that has undergone at least a step of carrying a toner image, and that charges the image carrier. Since the charging member has a coating layer on the surface, and the coating layer has a component having an affinity for the toner component forming the toner image, the charging characteristics fluctuate due to contamination of the charging member. Since the image carrier can be charged to a stable and uniform potential for an extremely long time, the initial image quality can be maintained without fluctuation. Further, the number of times of maintenance of the charging member can be reduced, and it is not necessary to add a new member, so that the cost can be reduced.

  According to the second aspect of the present invention, in a charging device including a charging member that is disposed in contact with or close to the surface of the image carrier that has undergone at least a step of carrying a toner image, and that charges the image carrier. A coating layer is formed on the surface of the charging member, and the coating layer includes a component having an affinity for the toner component that forms the toner image, and adheres the toner remaining on the image carrier to the coating layer. Because it has directivity, it is possible to suppress charging characteristics fluctuation due to contamination of the charging member, and to charge the image carrier to a stable and uniform potential for an extremely long period of time, so that the initial image quality Can be maintained without fluctuation. Further, the number of times of maintenance of the charging member can be reduced, and it is not necessary to add a new member, so that the cost can be reduced.

  According to the third aspect of the present invention, in the charging device according to the first or second aspect, the component having affinity and the other components of the coating layer are incompatible with each other. The fluctuation suppressing function can be improved.

  According to a fourth aspect of the present invention, in the charging device according to any one of the first to third aspects, the affinity component is the same as the resin component constituting the binder resin of the toner. Therefore, it is possible to suppress fluctuations in charging characteristics due to contamination of the charging member, and to charge the image carrier to a stable and uniform potential for an extremely long period of time, so that the initial image quality can be maintained without fluctuation. can do. Further, the number of times of maintenance of the charging member can be reduced, and it is not necessary to add a new member, so that the cost can be reduced.

According to a fifth aspect of the present invention, in the charging device according to any one of the first to fourth aspects, the coating layer contains an electrically conductive substance, and the volume resistance of the charging member is 1 × 10 ^3. Since it is Ω · cm to 1 × 10 ¹² Ω · cm, it is possible to reliably improve the charging characteristic fluctuation suppressing function.

  According to the invention described in claim 6, in the charging device according to any one of claims 1 to 5, the content of the component having affinity is 10 to 40% by weight with respect to the total amount of the coating layer. Therefore, it is possible to improve the charging characteristic fluctuation suppressing function while maintaining the mechanical strength of the charging member.

  According to a seventh aspect of the present invention, in the charging device according to any one of the first to fifth aspects, the component having the affinity is a linear polyester resin composition, a linear polyol resin composition, a linear The styrene-acrylic resin composition or at least one of these cross-linked products can suppress variation in charging characteristics due to contamination of the charging member, and can stabilize the image carrier over a very long period of time. Since the potential can be charged, the initial image quality can be maintained without being changed. Further, the number of times of maintenance of the charging member can be reduced, and it is not necessary to add a new member, so that the cost can be reduced.

  According to the invention described in claim 8, in the charging device according to any one of claims 1 to 5, the measurement hardness of the charging member measured by the Asker C hardness meter is 20 to 90 degrees. It is possible to improve the charging characteristic fluctuation suppressing function while reducing the load on the image carrier.

  According to the invention of claim 9, an image carrier, a charging device for charging the image carrier, a latent image forming device for forming a latent image on the image carrier, and a latent image on the image carrier. In the image forming apparatus having a developing device that visualizes the toner image as a toner image, the charging device is the charging device according to claim 1. An effect can be obtained.

  According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the charging device includes a voltage application device that applies a DC voltage or a voltage in which an AC voltage is superimposed on the DC voltage. Therefore, the charge amount can be made more uniform, which can further contribute to the suppression of fluctuations in charging characteristics.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the ninth or tenth aspect, the transfer device includes a plurality of image carriers, and transfers the toner images on the image carriers onto the recording medium. Therefore, the above effects can be obtained in the tandem direct transfer system.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to the ninth or tenth aspect of the present invention, the image forming apparatus includes a plurality of image carriers, and the toner images on these image carriers are transferred onto the intermediate transfer member in an overlapping manner. Since the transfer device for transferring the superimposed image on the body onto the recording medium is provided, the above-described effects can be obtained in the tandem type intermediate transfer system.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, the circularity SR = peripheral length of a circle having the same area as the particle projection area / perimeter length of the particle projection image Since the circularity SR of the toner represented by the formula is 0.93 to 1.00, it is possible to suppress a change in charging characteristics due to contamination of the charging device, and a toner suitable for obtaining a high-quality image. Even if it is used, the image carrier can be charged to a stable and uniform potential for an extremely long period of time, so that an initial high-quality image can be maintained without fluctuating for a long period of time.

  According to the fourteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, since the weight average diameter D4 of the toner is 3 to 10 μm, the charging device is contaminated. Even if a toner suitable for obtaining a high-quality image is used, the image carrier can be charged to a stable and uniform potential for an extremely long period of time. A quality image can be maintained without being changed over a long period of time.

  According to the fifteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to twelfth aspects, the ratio (D4 / D1) of the weight average diameter D4 and the number average diameter D1 of the toner is 1. Since it was determined to be 00 to 1.40, it is possible to suppress fluctuations in charging characteristics due to contamination of the charging device, and even if a toner suitable for obtaining a high-quality image is used, the image carrier can be used for a very long time. Since it can be charged to a stable and uniform potential, an initial high-quality image can be maintained without being fluctuated over a long period of time.

  According to the sixteenth aspect of the present invention, at least the image carrier, a charging device that charges the image carrier, a latent image forming device that forms a latent image on the image carrier, and a latent image on the image carrier. In the process cartridge integrally including a developing device that visualizes an image as a toner image, the charging device is the charging device according to claim 1. The effects of any one of claims 1 to 8 can be obtained.

According to the seventeenth aspect of the present invention, in the process cartridge according to the sixteenth aspect, the circularity of the toner represented by the equation of circularity SR = perimeter of the circle having the same area as the particle projection area / perimeter of the particle projection image Since the degree SR is 0.93 to 1.00, charging characteristics fluctuation due to contamination of the charging device can be suppressed, and even if a toner suitable for obtaining a high-quality image is used, it can be used for a very long time. Since the image bearing member can be charged to a stable and uniform potential, the initial high-quality image can be maintained without fluctuating over a long period of time.

  According to the eighteenth aspect of the present invention, in the process cartridge according to the sixteenth aspect, since the weight average diameter D4 of the toner is 3 to 10 μm, it is possible to suppress a change in charging characteristics due to contamination of the charging device. Even if a toner suitable for obtaining a high-quality image is used, the image bearing member can be charged to a stable and uniform potential for an extremely long period of time, so that the initial high-quality image fluctuates over a long period of time. Can be maintained.

  According to the nineteenth aspect of the present invention, in the process cartridge according to the sixteenth aspect, the ratio (D4 / D1) of the weight average diameter D4 and the number average diameter D1 of the toner is 1.00 to 1.40. As a result, it is possible to suppress charging characteristic fluctuations due to contamination of the charging device, and to charge the image carrier to a stable and uniform potential for an extremely long period of time even when using a toner suitable for obtaining a high-quality image. Therefore, the initial high-quality image can be maintained without being changed over a long period of time.

  According to the twentieth aspect of the present invention, in the image forming apparatus detachably including the process cartridge, the process cartridge is the process cartridge according to any one of the sixteenth to nineteenth aspects. Since it is possible to suppress fluctuations in charging characteristics due to contamination of the apparatus and use a toner suitable for obtaining a high-quality image, the image carrier can be charged to a stable and uniform potential for an extremely long period of time. An initial high-quality image can be maintained without being changed over a long period of time.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.
First, an outline of the configuration of a color copying machine as an image forming apparatus according to the present embodiment will be described with reference to FIG.
The image forming unit 10 of the color copying machine 100 includes drum-shaped photoconductors 1Y, 1M, 1C, and the like as image carriers capable of carrying images of toners of complementary colors (yellow, magenta, cyan, black). 1K is juxtaposed along the extended surface of the intermediate transfer belt 50 as an intermediate transfer member of the transfer device 5.
The photoconductor 1Y will be described as a representative. Around the photoconductor 1Y, a charging device 2, a writing device 3 as a latent image forming device, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged. The other photoconductors 1M, 1C, and 1K also have the same configuration, and are distinguished by assigning reference numerals corresponding to the respective colors, and description thereof is omitted.
The intermediate transfer belt 50 is supported by rollers 30, 31, and 32, and primary transfer rollers 33 </ b> Y, 33 </ b> M, 33 </ b> C, and 33 </ b> K serving as primary transfer units are disposed on the inner side of the intermediate transfer belt 50 corresponding to the respective photoreceptors 1. . At a position facing the roller 32, a secondary transfer roller 34 is disposed as a secondary transfer unit for collectively transferring the superimposed image on the intermediate transfer belt 50 onto the recording medium.
In such a configuration, image formation is performed by the following operation.

A series of processes for image formation will be described using a negative-positive process. In the case of contents common to all the photosensitive members and the developing device, the photosensitive member is simply indicated by reference numeral 1 and the developing device is indicated by reference numeral 4.
The photoreceptor 1 having the organic photoconductive layer is neutralized by a neutralizing lamp (not shown) or the like, and is uniformly negatively charged by a charging device 2 having a charging member described later.
When the charging device 2 charges the photosensitive member 1, a voltage of an appropriate magnitude suitable for charging the photosensitive member 1 to a desired potential from the voltage applying device described later to the charging member or an alternating current thereto. A charging voltage superimposed with a voltage is applied.
The charged photoreceptor 1 is subjected to latent image formation (the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential) by laser light irradiated by a writing device 3 such as a laser optical system. It is.
Laser light is emitted from a semiconductor laser, and the surface of the photoconductor 1 is scanned in the direction of the rotation axis of the photoconductor 1 by a polygonal polygon mirror that rotates at high speed.

The latent image formed in this manner is developed with a developer made of toner particles or a mixture of toner particles and carrier particles supplied on a developing sleeve as a developer carrying member in the developing device 4, and toner A visual image is formed.
At the time of developing the latent image, a voltage of an appropriate magnitude or a developing bias in which an alternating voltage is superimposed on the developing sleeve is applied to the developing sleeve from the voltage applying device to the developing sleeve. The
The toner images formed on the photoreceptors 1Y, 1M, 1C, and 1K corresponding to the respective colors are sequentially transferred onto the intermediate transfer belt 50 by primary transfer rollers 33Y, 33M, 33C, and 33K as primary transfer units. Is done. At this time, it is preferable that a potential having a polarity opposite to the toner charging polarity is applied to the primary transfer roller 33 as a transfer bias. Thereafter, the intermediate transfer belt 50 is separated from the photoreceptor 1, and a transfer image is obtained.
The superimposed toner images transferred onto the intermediate transfer belt 50 are collectively transferred by the secondary transfer roller 34 onto a recording medium such as paper fed from the paper feeding device 200.

The recording medium fed from the selected paper feed cassette of the paper feed device 200 is temporarily stopped by the registration roller pair 36 and the oblique shift is corrected, and then a predetermined timing is given to the secondary transfer portion of the secondary transfer roller 34. It is conveyed by.
The recording medium on which the superimposed images are collectively transferred is conveyed by the conveyance belt 37 and sent to the fixing device 7 where the toner image is fixed by heat and pressure. After the fixing, the recording medium is discharged and stacked on the discharge tray 8 by the discharge roller pair 38. In the case of duplex copying, the sheet is conveyed to the duplex unit 39 and again toward the registration roller pair 36.

The toner particles remaining on the photoreceptor 1 after the primary transfer are removed and collected by the cleaning device 6, and the toner particles remaining on the intermediate transfer belt 50 after the secondary transfer are removed and collected by the cleaning device 35.
The cleaning device 6 is not indispensable. In particular, in the use of a toner having a high toner circularity SR (described later) and good transfer, the amount of residual toner on the photoreceptor 1 after transfer is small. As will be described in detail below, according to the charging device 2 in the present embodiment, the charging potential to the photosensitive member 1 can be maintained sufficiently stably without the cleaning device 6.
In the present embodiment, the image forming apparatus is configured to perform secondary transfer using the intermediate transfer belt 50. However, the toner images of the plurality of photoreceptors 1 are sequentially stacked on the recording medium while the recording medium is conveyed by the conveying belt. It is good also as a structure which transfers.

Each photosensitive member 1, developing device 4 and the like can be integrally configured as a process cartridge that is detachable from the image forming apparatus main body. The configuration will be described with reference to FIG. However, the color code is omitted.
The above-described photoreceptor 1, charging device 2, developing device 4, and cleaning device 6 are accommodated integrally in the cartridge main body 301 of the process cartridge 300.
The charging device 2 includes a charging roller 20 as a charging member and a cleaning roller 21.
The developing device 4 includes a developing sleeve 4a and developer agitating and conveying members 4b and 4c for agitating and conveying the developer in the developing casing to circulate. A toner replenishing section 4d is provided above the developer stirring and conveying member 4c.
The cleaning device 6 includes a cleaning blade 61 that contacts the surface of the photoreceptor 1, a lubricant application brush 62 that is provided on the upstream side of the cleaning blade 61 and contacts the surface of the photoreceptor 1, and the lubricant application brush 62. , A cleaning roller 65 provided on the upstream side of the lubricant application brush 62, a blade 66 that contacts the surface of the cleaning roller 65, a recovery member 67 that recovers and conveys the removed toner, and the like. have.

In the case of the process cartridge, as in the case of the image forming apparatus, when the photosensitive member 1 is charged by the charging device 2, the photosensitive member 1 is charged to a desired potential from a voltage applying device described later to a charging member. A voltage of an appropriate magnitude suitable for the above or a charging voltage obtained by superimposing an AC voltage thereon is applied.
The charged photoconductor 1 forms a latent image with a laser beam L irradiated by a latent image forming apparatus such as a laser optical system (the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential). Is done.
Laser light L is emitted from a semiconductor laser and scans the surface of the photoconductor 1 in the direction of the rotation axis of the photoconductor 1 by a polygonal polygon mirror that rotates at high speed.
The latent image formed in this manner is developed with a developer made of toner particles or a mixture of toner particles and carrier particles supplied onto a developing sleeve 4a which is a developer carrying member in the developing device 4, and the toner A visible image is formed.

At the time of developing the latent image, a developing bias in which an appropriate voltage or an alternating voltage is superimposed on the voltage between the exposed portion and the non-exposed portion of the photosensitive member 1 is applied from the voltage applying device to the developing sleeve 4a. The
The toner image formed on the photoreceptor 1 is transferred onto the intermediate transfer belt 50 by the primary transfer roller 33. At this time, it is preferable that a potential having a polarity opposite to that of toner charging is applied to the primary transfer roller 33 as a transfer bias. Thereafter, the intermediate transfer belt 50 is separated from the photoreceptor 1 to obtain a transfer image.
Further, the toner particles remaining on the photoreceptor 1 are removed by the cleaning blade 61, and a part of the toner particles is collected in a toner collection chamber (not shown) in the cleaning device 6.
Also in the present embodiment, the cleaning device 6 is not essential, and in particular, in the use of toner having a large toner circularity SR (described later) and good transfer, the amount of residual toner on the photosensitive member 1 after transfer. As will be described in detail later, according to the charging device 2 of the present embodiment, the charging potential of the photosensitive member 1 is sufficiently increased over a long period of time longer than the normal use period of the process cartridge 300. Stable and maintainable.

The charging device 2 will be described with reference to FIGS. In FIG. 1, the cleaning roller 21 is omitted.
The charging roller 20 disposed opposite to and in contact with the photoconductor 1 as an image carrier has a base body 20a and a coating layer 20b. As shown in FIG. 2, the coating layer targeted by the present invention is a surface coating layer 20c that is the surface side of the coating layer 20b. A voltage for charging the photosensitive member 1 is applied to the charging roller 20 by a high voltage power supply 25 as a voltage applying device.
As shown in FIG. 3, it is good also as a structure which provides the inner coating layer 20d in the outer side of the base | substrate 20a, and provides the surface coating layer 20c in the surface side.
The surface coating layer 20c includes a resin or rubber, or has a configuration including a resin and rubber, and has a component having an affinity for a toner component.
In this embodiment, the same resin component as the binder resin of the toner to be used and an electrically conductive material are contained.
By the charging roller 20 to which a high voltage is applied, the photosensitive member 1 is charged to have a separately set potential.

Hereinafter, the present invention (this embodiment) will be described in more detail.
As a result of continuous studies to solve the above-described problems of the prior art, the present inventors have provided a charging member (charging roller 20) at least on the surface of the image carrier that has undergone a step of carrying a toner image. In a charging device that is placed in contact with or in close proximity and charges the image carrier (photosensitive member 1), for example, the coating layer of the charging member has the same component as the resin component constituting the toner binder resin, or is electrically By containing a conductive substance and setting the volume resistance of the charging member to a predetermined value, the improvement effect for applying a stable charging potential to the image carrier for a very long time is extremely remarkable. I found it.

About the effect, it is guessed as follows.
By having a common composition component between the material of the coating layer (surface coating layer 20c) of the charging member and the toner binder resin, the charging member has a surface state that is similar to a state in which the toner resin is partially attached. ing.
By forming such a charging member surface state in advance, even if toner remaining on the image carrier adheres to the charging member surface, the charging member surface state does not fluctuate and can be stably initialized. The characteristic equivalent to the state can be maintained for a long time.
The toner remaining on the image bearing member has a particularly high affinity for the resin and rubber constituting the surface of the coating layer of the charging member or the resin component constituting the binder resin of the toner among the resin or rubber component. Therefore, it adheres more to this part than the other components of the coating layer. As a result, the toner does not cover other parts of the coating layer surface of the charging member, and the function of the charging member can be maintained over a long period of time, so that the charging member characteristics such as charging performance and mechanical strength are reduced. Therefore, it is considered that it enables long-term use as a charging device.
In other words, on the premise that toner adheres to the surface of the charging member, if the toner adhesion state is such that the charging characteristic of the charging member does not change even if the toner adheres, that is, the toner adheres to the charging characteristic. If the directivity that does not affect is given, the charging characteristic can be stabilized over a long period of time.

In the present embodiment, the configuration in which the coating layer has a component having an affinity for the toner component does not mean that the coating layer has locally, but substantially uniformly throughout the charging member. It means to have. The term “substantially uniform” means a uniform dispersion state in which charging characteristics do not change due to changes in thickness or the like due to uneven adhesion of toner to components having affinity.
In addition, it does not mean that toner does not adhere to areas other than the component area having affinity, but toner easily adheres to the component area having affinity to such an extent that the charging characteristics of the entire charging member can be maintained. It means to become.

From the viewpoint of volume resistance, when the volume resistance of the charging member is less than 1 × 10 ³ Ω · cm as a result of the experiment, the charging member resistance changes greatly locally due to the adhesion of a small amount of toner. It turns out that there is. Such local variation in electrical resistance causes charge concentration in a portion of the charging member having a lower resistance, and appears as uneven charging potential of the image carrier.
Further, when the volume resistance of the charging member exceeds 1 × 10 ¹² Ω · cm, it is not efficient because it is necessary to apply a larger voltage than necessary to the charging member in order to charge the image carrier. However, it was found that heat generation and local structural destruction occurred at the interface between the base member and the coating layer of the charging member. Therefore, it is disadvantageous for long-term use.

  The coating layer of the charging member of the present invention may be a single coating layer or a laminate of a plurality of coating layers. In addition, when the charging member is coated with a stack of a plurality of coating layers, the same resin component that constitutes the toner binder resin and the electrically conductive material are applied only to the coating layer on the most surface side. It only has to be included. Since the electrically conductive substance is responsible for the electrical stability of the charging member, the volume resistance can be further stabilized by adding it to the inner coating layer, which is a more preferable form. In this case, the electrically conductive substance may be used in different contents in the outermost surface coating layer and the inner coating layer, and the kinds thereof may be different.

  The resin and rubber materials that can be used for the charging member coating layer, together with the same resin component that constitutes the toner binder resin, are generally selected from one or more known materials. it can. Specifically, as the resin, polyolefin resin (for example, polyethylene, polypropylene); polyvinyl and polyvinylidene resin (for example, polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole) , Polyvinyl ether and polyvinyl ketone); vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of an organosiloxane bond or a modified product thereof; fluorine resin (for example, polytetrafluoroethylene, polyvinyl fluoride) Polyester; Polyurethane; Polycarbonate; Phenol resin; Amino resin (eg urea-form); Polyester; Polyvinylidene fluoride; Polychlorotrifluoroethylene); Aldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins); and epoxy resins.

Examples of the rubber include diene rubber, styrene-butadiene rubber (SBR), ethylene propylene rubber, isoprene rubber, nitrile rubber, urethane rubber, silicone rubber, hydrin rubber, norbornene rubber and the like. These rubbers may be used as solid rubber or foamed rubber. When foamed rubber is used as the rubber, it is preferable to provide a surface coating layer based on the gist of the present invention on the outside in order to prevent uneven charging due to surface pores.
A foaming agent can be mix | blended when a coating layer is made into a foam. Examples of the blowing agent include organic blowing agents such as dinitrosopentamethylenetetramine, azodicarbonamide, paratoluenesulfonylhydrazine, azobisisobutyronitrile, 4,4′-oxybisbenzenesulfonylhydrazide, or inorganic blowing agents such as sodium bicarbonate. Is mentioned.

In addition, paraffinic oil, naphthenic oil, aromatic oil and the like may be added as a softening agent. These are not particularly limited, but paraffinic oil or naphthenic oil is preferably used from the viewpoint of contamination of the photoreceptor.
Furthermore, in the coating layer, a crosslinking aid, a crosslinking accelerator, a crosslinking acceleration aid, a crosslinking retarder, a reinforcing agent, a filler, a tackifier, which are generally used as a compounding agent such as rubber, if necessary, A dispersant, a release agent, a bulking agent, and the like can be added.

  Further, in order to sufficiently bring out the effects of the present invention, the same resin component constituting the binder resin of the toner and the resin and rubber in the coating layer of the other charging member must be incompatible. Is preferred. In the case where they are compatible, the composition of the surface of the charging member becomes substantially uniform, so that the toner adheres to and adheres to the charging member easily over the entire surface, which is not preferable.

Electrically conductive materials include metals such as iron, gold and copper; iron oxides such as ferrite and magnetite; oxides such as bismuth oxide, molybdenum oxide, titanium oxide and tin oxide; ionic conductivity such as silver iodide and β-alumina Bodies, electrically conductive particles such as particles obtained by coating them on the particle surface, ionic electrolytes such as LiClO ₄ , LiBF ₄ , KBF ₄ , KSCN, NaSCN, LiCF ₃ SO _3, and quaternary ammonium Examples thereof include conductive polymers represented by salts.
Among these, furnace black or acetylene black, which is one of carbon blacks, can be effectively used because the electrical conductivity can be effectively adjusted by adding a small amount of low resistance fine powder.
When particles are used as the electrically conductive substance, it is necessary to make the particle diameter sufficiently smaller than the thickness of the coating layer in order to suppress variation in resistance, but the number average diameter is about 0.01 to 1 μm. Those are preferred.
The amount of these electrically conductive substances can be appropriately adjusted from the viewpoint of maintaining strength and ease of production unless departing from the spirit of the present invention. On the other hand, it is preferably used in an amount of about 2 to 30 parts by weight. When the amount exceeds 30 parts by weight, the coating layer may be cracked or permanently deformed. Depending on the selection of a sufficiently conductive material, the effect may not be exhibited, and the expression may vary.

Further, the content of the same resin component as that constituting the binder resin of the toner in the coating layer is preferably used in the range of 10 to 40% by weight and in the range of 20 to 35% by weight with respect to the total amount of the coating layer. More preferably used.
If the content exceeds 40%, cracks may occur, and it may be difficult to select other components to maintain the mechanical properties as the charging member. If the amount is less than 10% by weight, the adhesion and fixation of the toner may occur more often in the region where the same resin component as that constituting the binder resin of the toner exists or in the vicinity thereof. It may lack stability in using.

As a material constituting the toner for forming a toner image on the image bearing member, a material usually used as an electrophotographic toner can be applied without particular limitation.
Examples of general binder resins used in the toner include homopolymers of styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, and the like; and styrene / p-chlorostyrene copolymers. Styrene / propylene copolymer, styrene / vinyl toluene copolymer, styrene / vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, Styrene / octyl acrylate copolymer, styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, styrene / Acrylonitrile copolymer, styrene / vinyl methyl ketone copolymer, Styrene copolymers such as tylene / butadiene copolymer, styrene / isoprene copolymer, styrene / maleic acid copolymer; polymethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polybutyl methacrylate, etc. Acrylic ester-based homopolymers and copolymers thereof; polyvinyl derivatives such as polyvinyl chloride and polyvinyl acetate; polyester-based polymers, polyurethane-based polymers, polyamide-based polymers, polyimide-based polymers, polyol-based polymers, An epoxy polymer, a terpene polymer, an aliphatic or alicyclic hydrocarbon resin, an aromatic petroleum resin, and the like can be used, and these can be used alone or in combination, but are not particularly limited thereto. Of these, at least one selected from styrene-acrylic copolymer resins, polyester resins, and polyol resins is more preferable in terms of electrical characteristics, cost, and the like. Furthermore, it is more preferable to use a polyester-based resin and / or a polyol-based resin as having good fixing characteristics.

For the reasons described above, the same resin component as the binder resin of the toner contained in the coating layer of the charging member includes a linear polyester resin composition, a linear polyol resin composition, and a linear styrene acrylic resin. At least one of the compositions or these cross-linked products can be preferably used.
In addition, the same resin component that constitutes the binder resin of the toner has the same resin composition or the same resin composition as the resin occupying the largest proportion of the binder resins contained in the toner used together with the charging device. It is preferable that it is a resin composition containing the monomer component. When the resin composition containing the same monomer component is used, the monomer component content is preferably 40% by weight or more based on the same amount as the resin component constituting the binder resin of the toner. More preferably, it is at least% by weight.

On the other hand, the hardness measured by the Asker C hardness meter of the charging member is preferably 20 to 90 degrees, more preferably 25 to 70 degrees.
When the hardness of the charging member exceeds 90 degrees, the surface of the charging member becomes rigid. Therefore, when the toner comes into contact with the remaining image carrier, the toner is rubbed and subjected to a large load to cause plastic deformation. It may be extended. The toner deformed in this manner may contaminate a wide area of the charging member or contaminate the surface of the image carrier with a small amount, which hinders the longevity of the charging device and the image forming apparatus. Therefore, it is not preferable.
Further, when the hardness of the charging member is less than 20 degrees, the surface of the charging member becomes too soft, and fine particle components such as a fluidity imparting agent contained in the toner adhere to the surface of the charging part agent and are pushed in. There is a risk of piercing. Such a fine particle component is not preferable for stabilizing the image quality because it damages the surface of the image carrier or becomes a minute convex portion on the charging member and causes the discharge voltage to fluctuate.

As the voltage applied to the charging device when charging the image carrier, a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage can be preferably used.
By using a DC voltage as the charging voltage, the image carrier can be charged with a relatively low voltage, and by superimposing the AC voltage on this, the amount of charge can be made more uniform.

Next, the toner suitably used in the present invention will be described.
First, the toner of the present invention preferably has an average circularity of 0.93 to 1.00. In the present invention, a value obtained from the following formula is defined as circularity. This circularity is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere, and the circularity becomes smaller as the surface shape becomes more complicated.
Circularity SR = peripheral length of a circle having the same area as the particle projection area / perimeter length of the projected particle image When the average circularity is in the range of 0.93 to 1.00, the surface of the toner particles is smooth, Since the contact area between the toner particles and the photoconductor is small, transferability is excellent.
Since the toner particles have no corners, the developer agitation torque in the developing device is small, and the agitation drive is stabilized, so that no abnormal image is generated.
Since there are no angular toner particles in the toner forming dots, the pressure is uniformly applied to the entire toner forming dots when transferring to the transfer medium during transfer, and the transfer is not easily lost.
Since the toner particles are not angular, the abrasive power of the toner particles themselves is small, and the surfaces of the photoreceptor, the charging member and the like are not damaged or worn.
Next, a method for measuring the circularity will be described.
The circularity can be measured using a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics.
As a specific measuring method, 0.1 to 0.5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and further measurement is performed. Add about 0.1-0.5g of sample. The suspension in which the sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes.

In the present invention, the weight average diameter D4 of the toner is preferably 3 to 10 μm.
In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent.
If the weight average diameter D4 is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties tend to occur.
When the weight average diameter D4 exceeds 10 μm, it is difficult to suppress scattering of characters and lines.

In the toner of the present invention, the ratio of the weight average diameter D4 to the number average diameter D1 (D4 / D1) is preferably 1.00 to 1.40. The closer the value of (D4 / D1) is to 1, the sharper the particle size distribution of the toner.
Therefore, when (D4 / D1) is in the range of 1.00 to 1.40, the selective development due to the toner particle size does not occur, and the image quality is excellent.
Since the toner particle size distribution is sharp, the triboelectric charge amount distribution is also sharp, and fogging is suppressed.
When the toner particle diameter is uniform, the latent image dots are developed so as to be densely and orderly arranged, so that the dot reproducibility is excellent.

Next, a method for measuring the particle size distribution of toner particles will be described.
As an apparatus for measuring the particle size distribution of toner particles by the Coulter Counter method, there are Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.
First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution. Here, the electrolytic solution is prepared by preparing an about 1% NaCl aqueous solution using primary sodium chloride, and for example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the volume and number of toner particles or toner using a 100 μm aperture as an aperture. Volume distribution and number distribution are calculated. From the obtained distribution, the weight average diameter D4 and the number average diameter D1 of the toner can be obtained.
As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 .35 to less than 8.00 μm; 8.00 to less than 10.08 μm; 10.08 to less than 12.70 μm; 12.70 to less than 16.00 μm; 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

  In addition, as such a substantially spherical toner, a toner composition containing a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent in an aqueous medium in the presence of fine resin particles. A toner that undergoes crosslinking and / or elongation reaction is preferred. The toner produced by this reaction can reduce the hot offset by curing the toner surface, and can prevent the fixing device from becoming dirty and appearing on the image.

Examples of the prepolymer comprising a modified polyester resin that can be used for toner preparation include a polyester prepolymer (A) having an isocyanate group, and examples of a compound that extends or crosslinks with the prepolymer include amines (B). Can be mentioned.
Examples of the polyester prepolymer (A) having an isocyanate group include a polycondensate of a polyol (1) and a polycarboxylic acid (2) and a polyester having an active hydrogen group, which is further reacted with a polyisocyanate (3). Can be mentioned. Examples of the active hydrogen group possessed by the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are preferred.

  Examples of the polyol (1) include a diol (1-1) and a tri- or higher valent polyol (1-2). (1-1) alone or (1-1) and a small amount of (1-2) Mixtures are preferred. Diol (1-1) includes alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the alicyclic diol; bisphenol And alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. The trihydric or higher polyol (1-2) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

Examples of the polycarboxylic acid (2) include dicarboxylic acid (2-1) and trivalent or higher polycarboxylic acid (2-2). (2-1) alone and (2-1) with a small amount of ( The mixture of 2-2) is preferred. Dicarboxylic acid (2-1) includes alkylene dicarboxylic acid (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acid (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acid (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polycarboxylic acid (2-2) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (trimellitic acid, pyromellitic acid, and the like). In addition, as polycarboxylic acid (2), you may make it react with polyol (1) using the acid anhydride or lower alkyl ester (methyl ester, ethyl ester, isopropyl ester, etc.) of the above-mentioned thing.
The ratio of the polyol (1) and the polycarboxylic acid (2) is usually 2/1 to 1/1, preferably 1. as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. 5/1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.

Examples of the polyisocyanate (3) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); aromatic Diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; polyisocyanates such as phenol derivatives, oximes, caprolactam And a combination of two or more of these.
The ratio of the polyisocyanate (3) is usually 5/1 to 1/1, preferably 4 /, as the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. If the molar ratio of [NCO] is less than 1, the urea content in the modified polyester will be low, and the hot offset resistance will deteriorate. The content of the polyisocyanate (3) component in the prepolymer (A) having an isocyanate group at the terminal is usually 0.5 to 40% by weight, preferably 1 to 30% by weight, more preferably 2 to 20% by weight. It is. If it is less than 0.5% by weight, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40% by weight, the low-temperature fixability deteriorates.

The number of isocyanate groups contained per molecule in the prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. It is. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.
As amines (B), diamine (B1), trivalent or higher polyamine (B2), aminoalcohol (B3), aminomercaptan (B4), amino acid (B5), and amino acids B1-B5 blocked (B6) etc. are mentioned. Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane, Isophorone diamine etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine etc.) and the like. Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of B1 to B5 blocked amino groups (B6) include ketimine compounds and oxazoline compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

Furthermore, if necessary, the molecular weight of the urea-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).
The ratio of amines (B) is the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). The ratio is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] exceeds 2 or less than 1/2, the molecular weight of the urea-modified polyester (i) becomes low, and the hot offset resistance deteriorates. In the present invention, the polyester (i) modified with a urea bond may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

By these reactions, the modified polyester used in the toner of the present invention, especially the urea-modified polyester (i) can be prepared. These urea-modified polyesters (i) are produced by a one-shot method or a prepolymer method. The weight average molecular weight of the urea-modified polyester (i) is usually 10,000 or more, preferably 20,000 to 10,000,000, more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number-average molecular weight of the urea-modified polyester is not particularly limited when the unmodified polyester (ii) described below is used, and may be a number-average molecular weight that can be easily obtained to obtain the weight-average molecular weight. (I) When used alone, the number average molecular weight is usually 20000 or less, preferably 1000 to 10000, and more preferably 2000 to 8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.
Moreover, in this invention, not only polyester (i) modified | denatured with the said urea bond but polyester (ii) not modified | denatured with this (i) can also be contained as a binder resin component. By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color device are improved, which is preferable to single use. Examples of (ii) include the same polycondensates of polyol (1) and polycarboxylic acid (2) as in the polyester component (i) above, and preferred ones are also the same as (i). (Ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urea bond, and may be modified with a urethane bond, for example. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Accordingly, the polyester component (i) and (ii) preferably have similar compositions. When (ii) is contained, the weight ratio of (i) and (ii) is usually 5/95 to 80/20, preferably 5/95 to 30/70, more preferably 5/95 to 25/75, Particularly preferred is 7/93 to 20/80. When the weight ratio of (i) is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

The peak molecular weight of (ii) is usually 1000-30000, preferably 1500-10000, more preferably 2000-8000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 10,000, low-temperature fixability will deteriorate. The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The acid value of (ii) is usually 1-30, preferably 5-20. By having an acid value, it tends to be negatively charged.
In the present invention, the glass transition point (Tg) of the binder resin is usually 50 to 70 ° C., preferably 55 to 65 ° C. If the temperature is less than 50 ° C., the blocking of the toner during high-temperature storage deteriorates, and if it exceeds 70 ° C., the low-temperature fixability becomes insufficient. Due to the coexistence of the urea-modified polyester resin, the dry toner of the present invention tends to have good heat-resistant storage stability even when the glass transition point is low, as compared with known polyester-based toners. As the storage elastic modulus of the binder resin, the temperature (TG ′) at which the measurement frequency is 20 Hz is 10000 dyne / cm ² is usually 100 ° C. or higher, preferably 110 to 200 ° C. If it is less than 100 ° C, the hot offset resistance deteriorates.

  As the viscosity of the binder resin, the temperature (Tη) at 1000 poise at a measurement frequency of 20 Hz is usually 180 ° C. or lower, preferably 90 to 160 ° C. If it exceeds 180 ° C, the low-temperature fixability deteriorates. That is, TG ′ is preferably higher than Tη from the viewpoint of achieving both low temperature fixability and hot offset resistance. In other words, the difference between TG ′ and Tη (TG′−Tη) is preferably 0 ° C. or more. More preferably, it is 10 degreeC or more, Most preferably, it is 20 degreeC or more. The upper limit of the difference is not particularly limited. Further, from the viewpoint of achieving both heat-resistant storage stability and low-temperature fixability, the difference between Tη and Tg is preferably 0 to 100 ° C. More preferably, it is 10-90 degreeC, Most preferably, it is 20-80 degreeC.

  The binder resin can be produced by the following method. Polyol (1) and polycarboxylic acid (2) are heated to 150 to 280 ° C in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and the generated water is distilled off as necessary. Thus, a polyester having a hydroxyl group is obtained. Subsequently, at 40-140 degreeC, this is made to react with polyisocyanate (3), and the prepolymer (A) which has an isocyanate group is obtained. Further, (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a polyester modified with a urea bond. When (3) is reacted and (A) and (B) are reacted, a solvent can be used as necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to the isocyanate (3), such as tetrahydrofuran (such as tetrahydrofuran). When polyester (ii) not modified with urea bond is used in combination, (ii) is produced by the same method as polyester having a hydroxyl group, and this is dissolved in the solution after completion of the reaction of (i) and mixed. To do.

In addition, the toner used in the present invention can be produced generally by the following method, but is not limited thereto.
The aqueous medium used in the present invention may be water alone, or a solvent miscible with water may be used in combination. Examples of miscible solvents include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.), and the like.
The toner particles may be formed by reacting a dispersion composed of a prepolymer (A) having an isocyanate group in an aqueous medium with (B), or using a urea-modified polyester (i) produced in advance. good. As a method for stably forming a dispersion comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium, a toner raw material comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium is used. And a method of dispersing by shearing force. The prepolymer (A) and other toner compositions (hereinafter referred to as toner raw materials), a colorant masterbatch, a release agent, a charge control agent, an unmodified polyester resin, etc. are dispersed in an aqueous medium. It may be mixed at the time of formation, but it is more preferable to mix the toner raw materials in advance and then add and disperse the mixture in the aqueous medium.

In the present invention, other toner materials such as a colorant, a release agent, and a charge control agent do not necessarily have to be mixed when forming particles in an aqueous medium, but after the particles are formed. , May be added. For example, after forming particles containing no colorant, the colorant can be added by a known dyeing method.
The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. In order to make the particle size of the dispersion 2 to 20 μm, a high-speed shearing type is preferable. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C. Higher temperatures are preferred in that the dispersion made of urea-modified polyester (i) or prepolymer (A) has a low viscosity and is easy to disperse.

The amount of the aqueous medium used relative to 100 parts of the toner composition containing the urea-modified polyester (i) and the prepolymer (A) is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner composition is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical. Moreover, a dispersing agent can also be used as needed. The use of a dispersant is preferable in that the particle size distribution becomes sharp and the dispersion is stable.
In the step of synthesizing the urea-modified polyester (i) from the prepolymer (A), the amine (B) may be added and reacted before the toner composition is dispersed in the aqueous medium, or may be dispersed in the aqueous medium. An amine (B) may be added later to cause a reaction from the particle interface. In this case, urea-modified polyester is preferentially produced on the surface of the toner to be produced, and a concentration gradient can be provided inside the particles.
Anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamines, etc. as a dispersant for emulsifying and dispersing the oily phase in which the toner composition is dispersed in a liquid containing water Amine salts such as salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, imidazoline, alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, etc. Nonionic surfactants such as quaternary ammonium salt type cationic surfactants, fatty acid amide derivatives, polyhydric alcohol derivatives, such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl N, amphoteric surfactants such as N-dimethyl ammonium betaine and the like.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 31- [omega-fluoroalkyl (C6-C11) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [omega-fluoroalkanoyl (C6-C8) mono-N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carboxylic acid and metal salt, Perfluoroalkylcarboxylic acid (C7 to C13) and its metal salt, perfluoroalkyl (C4 to C12) sulfonic acid and its metal salt, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- (2hydroxyethyl) -Fluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Is mentioned.

Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-1101 , DS-102, (Taikin Kogyo Co., Ltd.), Megafuck F-l0, F-l20, F-113, F-191, F-812, F-833 (Dainippon Ink Co., Ltd.), Xtop EF-ichi 102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fagento F-100, F150 (manufactured by Neos).
Further, as the cationic surfactant, aliphatic quaternary ammonium salts such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6 1 C10) sulfonamidopropyltrimethylammonium salt which right the fluoroalkyl group, Benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, trade names include Surflon S-21 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries Co., Ltd.) ), Megafuck F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-32 (Tochem Products Co., Ltd.), Footgent F 1300 (Neos Co., Ltd.), and the like.
Moreover, tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, hydroxyapatite, etc. can be used as an inorganic compound dispersant which is hardly soluble in water.
Further, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride or other (meth) acrylic monomer containing a hydroxyl group, For example, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-2-acrylate -Hydroxypropyl, 3-chloro-2-methacrylic acid methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate, N -Methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or esters of compounds containing vinyl alcohol and carboxyl groups For example, pinyl acetate, pinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, pinylviridine, vinylpyrrolidone, vinylimidazole, ethyleneimine Homopolymers or copolymers such as those having a nitrogen atom or its heterocyclic ring, polyoxyethylene, polyoxypropylene, Oxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonylphenyl Polyoxyethylenes such as esters, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

In addition, when an acid such as calcium phosphate salt or an alkali-soluble substance is used as the dispersion stabilizer, the calcium phosphate salt is removed from the fine particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and then washing with water. To do. It can also be removed by operations such as enzymatic degradation.
When a dispersant is used, the dispersant can remain on the surface of the toner particles. However, it is preferable from the charged surface of the toner that the dispersant is washed and removed after the elongation and / or crosslinking reaction.
Furthermore, in order to lower the viscosity of the toner composition, a solvent in which the urea-modified polyester (i) or the prepolymer (A) is soluble can be used. The use of a solvent is preferable in that the particle size distribution becomes sharp. The solvent is preferably volatile from the viewpoint of easy removal. Examples of the solvent include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, Methyl ethyl ketone, methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform and carbon tetrachloride are preferred, and aromatic solvents such as toluene and xylene are more preferred. The usage-amount of the solvent with respect to 100 parts of prepolymers (A) is 0-300 parts normally, Preferably it is 0-100 parts, More preferably, it is 25-70 parts. When a solvent is used, it is removed by heating under normal pressure or reduced pressure after elongation and / or crosslinking reaction.

The elongation and / or crosslinking reaction time is selected depending on the reactivity of the isocyanate group structure of the prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. is there. The reaction temperature is usually 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.
In order to remove the organic solvent from the obtained emulsified dispersion, a method can be employed in which the temperature of the entire system is gradually raised and the organic solvent in the droplets is completely evaporated and removed. Alternatively, it is also possible to spray the emulsified dispersion in a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, and to evaporate and remove the aqueous dispersant together. . As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air streams heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used are generally used. Sufficient quality can be obtained with a short processing time such as spray dryer, belt dryer, rotary kiln.

When the particle size distribution at the time of emulsification dispersion is wide, and washing and drying processes are performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classification into a desired particle size distribution.
In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Of course, the classification operation may be performed after obtaining the powder as a powder after drying, but it is preferably performed in a liquid in terms of efficiency. The obtained unnecessary fine particles or coarse particles can be returned to the kneading step and used for forming particles. At that time, fine particles or coarse particles may be wet.
The dispersant used is preferably removed from the obtained dispersion as much as possible, but it is preferable to carry out it simultaneously with the classification operation described above.
By mixing the resulting dried toner powder with dissimilar particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or by giving mechanical impact force to the mixed powder By immobilizing and fusing on the surface, it is possible to prevent detachment of the foreign particles from the surface of the resulting composite particle.
Specific means include a method of applying an impact force to the mixture by blades rotating at high speed, a method of injecting and accelerating the mixture in a high-speed air stream, and causing particles or composite particles to collide with an appropriate collision plate, etc. is there. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) has been modified to reduce the pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron System (manufactured by Kawasaki Heavy Industries Ltd.), automatic mortar, etc.

Further, as the colorant used in the toner, pigments and dyes conventionally used as toner colorants can be used. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, Aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6C lake, chalcoa oil blue, chrome yellow, quinacridone red, benzidine yellow, rose bengal and the like can be used alone or in combination.
Furthermore, if necessary, in order to give the toner particles magnetic properties, magnetic components such as iron oxides such as ferrite, magnetite and maghemite, metals such as iron, cobalt and nickel, or alloys of these with other metals. May be contained alone or in combination in the toner particles. Moreover, these components can also be used / used together as a colorant component.

The number average diameter of the colorant in the toner used in the present invention is desirably 0.5 μm or less, preferably 0.4 μm or less, more preferably 0.3 μm or less.
When the number average diameter of the colorant in the toner is larger than 0.5 μm, the dispersibility of the pigment does not reach a sufficient level, and preferable transparency may not be obtained.
A colorant having a fine particle diameter of less than 0.1 μm is sufficiently smaller than a half wavelength of visible light, and thus is considered not to adversely affect light reflection and absorption characteristics. Therefore, the colorant particles of less than 0.1 μm contribute to good color reproducibility and transparency of the OHP sheet having a fixed image. On the other hand, if there are many colorants having a particle size larger than 0.5 μm, the transmission of incident light is hindered or scattered, and the brightness and color of the projected image of the OHP sheet tend to decrease. There is.
Further, if there are many colorants having a particle size larger than 0.5 μm, the colorant is detached from the surface of the toner particles, and various problems such as fogging, drum contamination, and poor cleaning are liable to occur. In particular, the colorant having a particle size larger than 0.7 μm is preferably 10% by number or less, more preferably 5% by number or less of the total colorant.
In addition, by adding a wetting liquid in advance with a part or all of the binder resin and kneading the colorant, the binder resin and the colorant are initially sufficiently adhered, In the toner production process, the colorant is dispersed more effectively in the toner particles, the dispersed particle diameter of the colorant is reduced, and better transparency can be obtained.

As the binder resin used for kneading in advance, the resins exemplified as the binder resin for toner can be used as they are, but are not limited thereto.
As a specific method for kneading the mixture of the binder resin and the colorant with the wetting liquid in advance, for example, the binder resin, the colorant and the wetting liquid are obtained after mixing with a blender such as a Henschel mixer. The obtained mixture is kneaded at a temperature lower than the melting temperature of the binder resin by a kneader such as a two-roll or three-roll to obtain a sample.
In addition, as the wetting liquid, a general one can be used in consideration of the solubility of the binder resin and the paintability with the colorant, but in particular, an organic solvent such as acetone, toluene, butanone, or water, It is preferable from the viewpoint of dispersibility of the colorant.
Among these, the use of water is more preferable from the viewpoint of environmental considerations and maintaining the dispersion stability of the colorant in the subsequent toner production process.
According to this manufacturing method, not only the particle diameter of the colorant particles contained in the obtained toner is reduced, but also the uniformity of the dispersion state of the particles is increased, so that the color reproducibility of the projected image by OHP is further improved. Get better.

In addition, as long as the configuration of the present invention is adopted, a release agent typified by wax may be contained in the toner together with the binder resin and the colorant.
Known release agents can be used, such as polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbons (paraffin wax, sazol wax, etc.); carbonyl group-containing wax, etc. .
Of these, carbonyl group-containing waxes are preferred. Carbonyl group-containing waxes include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18. -Octadecandiol diol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylenediamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide, etc.) And dialkyl ketones (such as distearyl ketone).
Among these carbonyl group-containing waxes, polyalkanoic acid esters are preferred. The melting point of these release agents is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. A wax having a melting point of less than 40 ° C adversely affects the heat-resistant storage stability, and a wax having a melting point of more than 160 ° C tends to cause a cold offset when fixing at a low temperature. Further, the melt viscosity of the wax is preferably 5 to 1000 cps, more preferably 10 to 100 cps, as a measured value at a temperature 20 ° C. higher than the melting point. Waxes exceeding 1000 cps have poor effects for improving hot offset resistance and low-temperature fixability. The content of the wax in the toner is usually 0 to 40% by weight, preferably 3 to 30% by weight.

In addition, a charge control agent may be contained in the toner as necessary in order to accelerate the toner charge amount and its rise. Here, since a color change occurs when a colored material is used as the charge control agent, a material that is colorless and close to white is preferable.
Any known charge control agent can be used. Examples include triphenylmethane dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkyls. Amide, phosphorus simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. Specifically, Bontron P-51 of a quaternary ammonium salt, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex, E-89 of a phenol condensate (above, Orient Chemical Co., Ltd.) Manufactured), TP-302 of quaternary ammonium salt molybdenum complex, TP-1415 (above, manufactured by Hodogaya Chemical Co., Ltd.), copy charge PSY VP2038 of quaternary ammonium salt, copy blue PR of triphenylmethane derivative, Quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, boron complex LR-147 (manufactured by Nippon Kalit Ltd), quinacridone, azo pigment, other sulfone Polymerization with functional groups such as acid groups, carboxyl groups, and quaternary ammonium salts Thing, and the like.

In the present invention, the amount of charge control agent used is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is uniquely limited. However, it is preferably used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the flowability of the developer is reduced, and the image density is reduced. Incurs a decline. These charge control agents can be dissolved and dispersed after being melt-kneaded with a masterbatch and resin, or may be added when directly dissolving and dispersing in an organic solvent, or may be fixed on the toner surface after preparation of toner particles. Also good.
Further, when the toner composition is dispersed in the aqueous medium during the toner production process, resin fine particles mainly for stabilizing the dispersion may be added.
The resin fine particles used may be any resin that can form an aqueous dispersion, and may be a thermoplastic resin or a thermosetting resin. For example, vinyl resins, polyurethane resins, epoxy resins, polyester resins, Examples thereof include polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, and polycarbonate resin. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.
The vinyl resin is a polymer obtained by homopolymerization or copolymerization of a vinyl monomer, such as a styrene- (meth) acrylate resin, a styrene-butadiene copolymer, a (meth) acrylic acid-acrylate polymer, Examples include, but are not limited to, styrene-acrylonitrile copolymers, styrene-maleic anhydride copolymers, styrene- (meth) acrylic acid copolymers, and the like.

Further, inorganic fine particles can be preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles.
The primary particle diameter of the inorganic fine particles is preferably 5 mμ to 2 μm, and particularly preferably 5 mμ to 500 mμ. Moreover, it is preferable that the specific surface area by BET method is 20-500 m <2> / g. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
In addition, polymer fine particles such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, methacrylic acid ester and acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine and nylon, thermosetting resin And polymer particles.

Such a fluidizing agent can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having a fluoroalkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .
Examples of the cleaning property improver for removing the developer after transfer remaining on the photosensitive member or the primary transfer medium include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, such as polymethyl methacrylate fine particles, polystyrene. Examples thereof include fine polymer particles produced by soap-free emulsion polymerization of fine particles and the like. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.

By using these toners, a high-quality toner image having excellent development stability can be formed as described above. However, the toner remaining on the image carrier without being transferred to the transfer medium or intermediate transfer medium by the transfer device is difficult to remove by the cleaning device due to its fineness and good rolling property. May end up. In order to completely remove the toner from the image carrier, it is necessary to strongly press a toner removing member such as a cleaning blade against the image carrier. Such a load not only shortens the life of the image carrier and the cleaning device, but also uses extra energy.
When the load on the image carrier is reduced, the toner on the image carrier is insufficiently removed, and the toner passes through the cleaning device, is transported to the charging device, adheres to the charging member, and changes the performance of the charging device. It becomes a factor to make.
As described above, the charging device of the present invention has a configuration in which the charging performance variation on the image carrier due to the adhesion of the toner to the charging member is highly suppressed. An extremely high quality image can be obtained stably over a long period of time.

  Similarly, by using the charging device of the present invention and the toner as described above in the process cartridge, the life of the parts in use can be greatly extended, so that the process cartridge can be easily reused. Can do.

Thus, the present invention will be described in more detail with reference to each example. However, the present invention is not limited to the following example. Here, “parts” are all parts by weight.
[Example 1]
(Charging member production example 1)
To 10 parts by weight of polynorbornene rubber, 20 parts by weight of naphthene oil is adsorbed to form a rubber-like elastic body, and 90 parts of ethylene-propylene-butadiene terpolymer (monomer weight ratio = 70/23/7) is added thereto. 10 parts of ketjen black as an electrically conductive substance, 30 parts of naphthenic oil as a softening agent, 5 parts of azodicarbonamide (hereinafter referred to as ADCA) as a foaming agent, 4,4′-oxybisbenzenesulfonylhydrazide (hereinafter referred to as OBSH) 5 parts, urea resin 3 parts as foaming aid, vulcanization acceleration aid 5 parts zinc oxide, stearic acid 1 part, crosslinking agent 2 parts sulfur, vulcanization accelerator 2 parts mercaptobenzothiazole, dibutyl 1 part of zinc dithiocarbamate and 1 part of tetramethyl uranium disulfide are mixed in an open roll, A composition was obtained.

Unvulcanized rubber is formed into a tube shape by extrusion molding, primary vulcanization is performed by steam vulcanization at 160 ° C for 30 minutes, and secondary vulcanization is performed by electric furnace at 200 ° C for 10 minutes, followed by vulcanization foaming Got the body. The tube thus formed was press-fitted into a 6 mm diameter metal core coated with an adhesive and polished to obtain a sponge roller having a diameter of 12 mmφ (thickness 3 mm, length 240 mm).
Next, linear polyester resin / phenyl silicone resin / Ketjen black is mixed at a solid content ratio of 30 parts / 65 parts / 5 parts into a toluene / methyl ethyl ketone (1/1) mixed solvent with a solid content of 50%. Then, a surface coating layer stock solution was prepared by dispersing in a porcelain ball mill (inner diameter: 200 mmφ, depth: 200 mm) using steel balls (5 mmφ) as dispersion media.

As the linear polyester resin, ethylene oxide addition alcohol of bisphenol A, propylene oxide addition alcohol of bisphenol A, and a condensation polymer of terephthalic acid (Mw = 5000) were used.
The filling amount of the steel balls was 40% by volume of the internal volume, and the charging amount of the surface coating layer stock solution was about 20%. Dispersion was performed at room temperature for 12 hours.
The surface coating layer undiluted solution was slowly added into water that had been previously added with a dispersant and stirred with a homogenizer. After the entire amount was added, the mixture was further stirred for 1 hour to obtain an emulsion coating for surface coating.
Using this emulsion coating material for surface coating, coating was performed by spraying on a sponge roller pretreated with a silane coupling agent to form a film thickness of about 100 μm. This was heated and dried at 120 ° C. for 30 minutes in an electric furnace to obtain a charging roller (R1).

The electrical resistance of the obtained charging roller was measured by pressing the roller molded body against a cylindrical aluminum drum and rotating the charging roller and the aluminum drum at a constant speed. A voltage of 100 V DC was applied between them, and the voltage applied to the resistor connected in series with the aluminum drum was measured. The ratio between the maximum value and the minimum value was defined as circumferential unevenness, and the value was 1.1. Furthermore, the volume resistance of the produced charging roller was calculated from the contact area obtained from the nip width and length of the contact portion between the charging roller and the aluminum drum and the thickness of the coating layer.
The volume resistance of the charging roller (R1) was 1 × 10 ⁷ Ω · cm.
The hardness of the charging roller was 45 degrees with Asker C.

(Toner Production Example 1)
79.5 parts of partially crosslinked polyester resin (ethylene oxide addition alcohol of bisphenol A,
Propylene oxide addition alcohol of bisphenol A,
Terephthalic acid, trimellitic acid condensation polymer,
(Mw = 15000, glass transition point = 61 ° C.)
Carbon black 15 parts Zirconium salt of di-tert-butylsalicylic acid 1 part Carnauba wax; 5 parts made by Noda Wax Co.

The mixture of the above composition is kneaded for 30 minutes with a two-roll kneader, then pulverized / classified with a mechanical pulverizer / airflow classifier, and further smoothed with a mechanical surface treatment device. A toner base was obtained.
Further, 1 part of hydrophobic silica fine particles and 1 part of hydrophobic titanium oxide fine particles were added to 100 parts of the toner base, and mixed for a total of 2 minutes with a Henschel mixer to obtain a toner (T1).
Therefore, one of the components constituting the coating layer of the charging roller R1 (linear polyester resin) and the resin component constituting the binder resin of the toner T1 (partially crosslinked polyester resin) become the same, and the affinity Have In the following examples, description of the presence of affinity due to the same component is omitted as appropriate.
The particle size distribution of the toner (T1) was measured with a Coulter counter TA2. The weight average diameter D4 was 6.2 μm and the number average diameter D1 was 5.4 μm.
Next, 920 parts of a carrier (weight average diameter D4 = 35 μm) obtained by applying a silicone coat to manganese ferrite magnetic particles and 80 parts of toner (T1) were mixed for 1 minute by a turbula mixer to obtain a two-component developer. .

Using a remodeling machine of the Ricoh color printer IPSiO color 8000, a charging roller (R1) is installed in the charging device, and using this developer, continuous image output of 300,000 A4 size, 6% image area originals A test was performed, and an initial image and a character image, a halftone image, and a solid image after continuous drawing were output to evaluate the image quality.
At this time, the voltage was applied to the charging device by applying a charging voltage obtained by superimposing an AC voltage having a peak-to-peak voltage of 2000 V and a frequency of 2000 Hz on a -600 V DC voltage.
The electrostatic charge image on the image carrier at the time of image output was background portion = −600V and image portion = −150V.
Further, a developing bias potential in which an AC voltage with a peak-to-peak voltage of 1500 V and a frequency of 2000 Hz was superimposed on a DC voltage (−450 V) was applied to the developing sleeve.
As the image quality evaluation, the character portion was thickened, the halftone image was blurred and toned, the solid image density, the background fogging stability, and the presence or absence of other defects in each image were evaluated.
Further, in order to evaluate the damage to the image forming process due to the contamination of the charging member, the state of the charging member and the image carrier was observed and rank evaluation was performed.
Initially, good image quality was obtained after 300,000 sheets, and it was found that the charging device and the image forming apparatus of the present invention are useful in both image quality and lifetime.
The image density was measured using a Macbeth densitometer (RD-914), and the other items were evaluated visually.
The charging member (charging roller 20) type, toner type, charging member volume resistance, hardness, toner weight average diameter, number average diameter, particle size ratio, and circularity are shown in Table 1. Initial and after 300,000 sheets The evaluation results are shown in Tables 2 and 3 (the same applies to other examples and comparative examples below).

[Example 2]
(Charging member production example 2)
A charging roller (similar to charging member production example 1) except that the ratio of linear polyester resin / phenyl silicone resin / ketchen black in the surface coating layer stock solution was 30 parts / 63 parts / 2 parts in terms of solid content. R2) was obtained.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R2) was used as the charging member used in the charging device.

[Example 3]
(Charging member production example 3)
A charging roller (similar to charging member production example 1) except that the ratio of linear polyester resin / phenyl silicone resin / ketchen black in the surface coating layer stock solution was 30 parts / 60 parts / 10 parts in terms of solid content. R3) was obtained.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R3) was used as the charging member used in the charging device.

[Example 4]
(Charging member production example 4)
To 10 parts by weight of polynorbornene rubber, 25 parts by weight of naphthene oil is adsorbed to form a rubber-like elastic body, and 90 parts of ethylene-propylene-butadiene terpolymer (monomer weight ratio = 70/23/7) is added thereto. 10 parts of ketjen black as an electrically conductive substance, 30 parts of naphthenic oil as a softening agent, 10 parts of azodicarbonamide (hereinafter referred to as ADCA) as a foaming agent, 4,4′-oxybisbenzenesulfonylhydrazide (hereinafter referred to as OBSH) 10 parts, 5 parts urea resin as a foaming aid, 5 parts zinc oxide as a vulcanization accelerator, 1 part stearic acid, 2 parts sulfur as a crosslinking agent, 2 parts mercaptobenzothiazole as a vulcanization accelerator, dibutyl 1 part of zinc dithiocarbamate and 1 part of tetramethyluranium disulfide are mixed in an open roll to form a conductive layer A rubber composition was obtained.

Unvulcanized rubber is formed into a tube shape by extrusion molding, primary vulcanization is performed by steam vulcanization at 160 ° C for 30 minutes, and secondary vulcanization is performed by electric furnace at 200 ° C for 10 minutes, followed by vulcanization foaming Got the body. The tube thus formed was press-fitted into a 6 mm diameter metal core coated with an adhesive and polished to obtain a sponge roller having a diameter of 12 mmφ (thickness 3 mm, length 240 mm).
A charging roller (R4) having a low hardness was obtained in the same manner as in the charging member production example 1 except that this roller was used as the sponge roller.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R4) was used as the charging member used in the charging device.

[Example 5]
(Charging member production example 5)
Linear polyester resin / phenylsilicone resin / Ketjen black at a solid content ratio of 35 parts / 58 parts / 7 parts into a toluene / methyl ethyl ketone (1/1) mixed solvent so that the solid content is 30%. Then, a surface coating layer solution was prepared by dispersing in a porcelain ball mill (inner diameter 200 mmφ, depth 200 mm) using steel balls (5 mmφ) as dispersion media.
Using this surface coating layer solution, a substrate roller (core metal) having a diameter of 12 mmφ was coated by spraying to form a coating layer having a thickness of about 200 μm. This was heated and dried at 120 ° C. for 30 minutes in an electric furnace to obtain a charging roller (R5) with high hardness.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R5) was used as the charging member used in the charging device.

[Example 6]
(Charging member production example 6)
25 parts by weight of naphthenic oil is adsorbed to 10 parts by weight of polynorbornene rubber to obtain a rubber-like elastic body, and 90 parts of ethylene-propylene-butadiene terpolymer (monomer weight ratio = 70/25/5) 10 parts of ketjen black as an electrically conductive material, 30 parts of naphthenic oil as a softener, 15 parts of azodicarbonamide (hereinafter referred to as ADCA) as a foaming agent, 4,4′-oxybisbenzenesulfonylhydrazide (hereinafter referred to as OBSH) 15 parts, 5 parts of urea resin as a foaming aid, 5 parts of zinc oxide as a vulcanization accelerator, 1 part of stearic acid, 2 parts of sulfur as a crosslinking agent, 2 parts of mercaptobenzothiazole as a vulcanization accelerator, dibutyl 1 part of zinc dithiocarbamate and 1 part of tetramethyluranium disulfide are mixed in an open roll to form a conductive layer A rubber composition was obtained.

Unvulcanized rubber is formed into a tube shape by extrusion molding, primary vulcanization is performed by steam vulcanization at 160 ° C for 30 minutes, and secondary vulcanization is performed by electric furnace at 200 ° C for 10 minutes, followed by vulcanization foaming Got the body. The tube thus formed was press-fitted into a 6 mm diameter metal core coated with an adhesive and polished to obtain a sponge roller having a diameter of 12 mmφ (thickness 3 mm, length 240 mm).
A charging roller (R6) having a low hardness was obtained in the same manner as in the charging member production example 1 except that this roller was used as the sponge roller.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R6) was used as the charging member used in the charging device.

[Example 7]
(Charging member production example 7)
Linear polyester resin / phenylsilicone resin / Ketjen black at a solid content ratio of 35 parts / 58 parts / 7 parts into a toluene / methyl ethyl ketone (1/1) mixed solvent so that the solid content is 30%. Then, a surface coating layer solution was prepared by dispersing in a porcelain ball mill (inner diameter 200 mmφ, depth 200 mm) using steel balls (5 mmφ) as dispersion media.
Using this surface coating layer solution, a substrate roller (core metal) having a diameter of 12 mmφ was coated by spraying to form a coating layer having a thickness of about 80 μm. This was heated and dried at 120 ° C. for 30 minutes in an electric furnace to obtain a charging roller (R7) with high hardness.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R7) was used as the charging member used in the charging device.

[Example 8]
(Charging member production example 8)
Linear styrene-acrylic resin / phenylsilicone resin / Ketjen black at a solid content ratio of 30 parts / 65 parts / 5 parts into a toluene / methyl ethyl ketone (1/1) mixed solvent with a solid content of 50% As described above, a surface coating layer stock solution was prepared by dispersing in a porcelain ball mill (inner diameter: 200 mmφ, depth: 200 mm) using steel balls (5 mmφ) as a dispersion medium.
As the linear styrene-acrylic resin, a copolymer of styrene, 2 ethylhexyl methacrylate, and normal butyl acrylate (Mw = 5500) was used.
A charging roller (R8) was obtained in the same manner as in Example 1 except that this was used as the surface coating layer stock solution.

(Toner Production Example 2)
60.0 parts of styrene acrylic resin (styrene, 2-ethylhexyl methacrylate,
A copolymer of normal butyl acrylate,
Mw = 18000)
Partially cross-linked polyester resin 19.5 parts (ethylene oxide addition alcohol of bisphenol A,
Propylene oxide addition alcohol of bisphenol A,
Terephthalic acid, trimellitic acid condensation polymer,
Mw = 15000)
Carbon black 15 parts Zirconium salt of di-tert-butylsalicylic acid 1 part Carnauba wax; manufactured by Noda Wax Co., Ltd. 5 parts Toner (in the same manner as in Toner Production Example 1 except that the mixture having the above composition was used as the toner composition) T2) was obtained.

Accordingly, one of the components constituting the coating layer of the charging roller R8 (linear polyester resin) and the resin component constituting the binder resin of the toner T2 (partially crosslinked polyester resin) are the same, and the affinity Have
When the particle size distribution of the toner (T2) was measured with a Coulter counter TA2, the weight average diameter D4 = 6.8 μm and the number average diameter D1 = 5.2 μm.
Next, 920 parts of a carrier (weight average diameter D4 = 35 μm) obtained by applying a silicone coat to manganese ferrite magnetic particles and 80 parts of toner (T2) were mixed for 1 minute by a tumbler mixer to obtain a two-component developer. .
Each evaluation was performed in the same manner as in Example 1 except that a charging roller (R8) was used as a charging member used in the charging device, a toner (T2) and a toner (T2) prepared as a developer were used. I did it.

[Example 9]
(Charging member production example 9)
Linear polyester resin / phenylsilicone resin / Ketjen black at a solid content ratio of 40 parts / 53 parts / 7 parts into a toluene / methyl ethyl ketone (1/1) mixed solvent so that the solid content is 30%. Then, a surface coating layer solution was prepared by dispersing in a porcelain ball mill (inner diameter 200 mmφ, depth 200 mm) using steel balls (5 mmφ) as a dispersion medium.
Using this surface coating layer solution, a substrate roller (core metal) having a diameter of 12 mmφ was coated by spraying to form a coating layer having a thickness of about 200 μm. This was heated and dried at 120 ° C. for 30 minutes in an electric furnace to obtain a charging roller (R9) having a larger resin component having the same composition as the toner.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R9) was used as the charging member used in the charging device.

[Example 10]
(Charging member production example 10)
Same as the charging member production example 1 except that the ratio of the linear polyester resin / phenyl silicone resin / Ketjen black in the surface coating layer stock solution is 10 parts / 85 parts / 5 parts in solid content ratio A charging roller (R10) having a small resin component was obtained.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R10) was used as the charging member used in the charging device.

[Example 11]
(Charging member production example 11)
Linear polyester resin / phenyl silicone resin / Ketjen black in a ratio of 45 parts / 48 parts / 7 parts in a solid content ratio into a toluene / methyl ethyl ketone (1/1) mixed solvent so that the solid content is 30%. Then, a surface coating layer solution was prepared by dispersing in a porcelain ball mill (inner diameter 200 mmφ, depth 200 mm) using a steel ball (5 mmφ) as a dispersion medium.
Using this surface coating layer solution, a substrate roller (core metal) having a diameter of 12 mmφ was coated by spraying to form a coating layer having a thickness of about 200 μm. This was heated and dried at 120 ° C. for 30 minutes in an electric furnace to obtain a charging roller (R11) containing a large amount of resin components having the same composition as the toner.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R11) was used as the charging member used in the charging device.

[Example 12]
(Charging member production example 12)
Same as the charging member production example 1, except that the ratio of the linear polyester resin / phenyl silicone resin / ketchen black in the surface coating layer stock solution is 5 parts / 90 parts / 5 parts in solid content ratio A charging roller (R12) having a small resin component was obtained.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R12) was used as the charging member used in the charging device.

[Comparative Example 1]
Each evaluation was performed in the same manner as in Example 1 except that a charging roller (R1) was used as a charging member used in the charging device, a toner (T2) and a toner (T2) prepared as a developer were used. I did it.
One of the components constituting the coating layer of the charging roller R1 (linear polyester resin) and the resin component constituting the binder resin of the toner T2 (styrene acrylic resin) are not the same and have an affinity. do not do.

[Comparative Example 2]
(Charging member production example 13)
Charge the resin component with the same composition as the toner in the same manner as in the charging member production example 1 except that the ratio of the phenyl silicone resin / Ketjen black to the surface coating layer stock solution is 95 parts / 5 parts by solid content. A roller (R13) was obtained. Therefore, the affinity between the component constituting the coating layer of the charging roller R13 and the resin component constituting the binder resin of the toner T1 is low. As shown in Table 3, under the conditions of Comparative Example 2, after 300,000 sheets, deterioration of gradation and member deterioration are observed.
This means that if the amount is small even if there is affinity, the directivity of toner adhesion becomes unstable, and the amount of toner adhering outside the affinity component region increases.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R13) was used as the charging member used in the charging device.

[Comparative Example 3]
(Charging member production example 14)
A charging roller (similar to charging member production example 1) except that the ratio of linear polyester resin / phenyl silicone resin / ketchen black in the surface coating layer stock solution was 30 parts / 64 parts / 1 part in terms of solid content. R14) was obtained.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R14) was used as the charging member used in the charging device.
One of the components constituting the coating layer of the charging roller R14 (linear polyester resin) and the resin component (partially crosslinked polyester resin) constituting the binder resin of the toner T1 are the same and have an affinity. However, as shown in Table 1, the volume resistance of the charging member deviates from the upper limit (1 × 10 ¹² Ω · cm) defined in the present invention (Claim 5).

[Comparative Example 4]
(Charging member production example 15)
A charging roller (similar to charging member production example 1) except that the ratio of linear polyester resin / phenylsilicone resin / ketchen black in the surface coating layer stock solution was 30 parts / 55 parts / 15 parts in terms of solid content. R15) was obtained.
Each evaluation was performed in the same manner as in Example 1 except that the charging roller (R15) was used as the charging member used in the charging device.
One of the components constituting the coating layer of the charging roller R15 (linear polyester resin) and the resin component constituting the binder resin of the toner T1 (partially crosslinked polyester resin) are the same and have an affinity. However, as shown in Table 1, the volume resistance of the charging member is outside the lower limit (1 × 10 ³ Ω · cm) defined in the present invention (Claim 5).

[Example 13]
(Binder Resin Synthesis Example 1)
724 parts of bisphenol A ethylene oxide 2-mole adduct, 276 parts of isophthalic acid and 2 parts of dibutyltin oxide were placed in a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and reacted at 230 ° C for 8 hours under normal pressure. The reaction was further carried out at a reduced pressure of 10 to 15 mmHg for 5 hours, followed by cooling to 160 ° C., 32 parts of phthalic anhydride was added thereto, and the reaction was carried out for 2 hours.
Subsequently, it cooled to 80 degreeC and reacted with 188 parts of isophorone diisocyanate in ethyl acetate for 2 hours, and the isocyanate containing prepolymer (P1) was obtained.
Next, 267 parts of the prepolymer (P1) and 14 parts of isophoronediamine were reacted at 50 ° C. for 2 hours to obtain a urea-modified polyester (U1) having a weight average molecular weight of 64,000.
In the same manner as above, 724 parts of bisphenol A ethylene oxide 2 mol adduct and 276 parts of terephthalic acid were polycondensed at 230 ° C. for 8 hours under normal pressure, and then reacted for 5 hours at a reduced pressure of 10 to 15 mmHg to give a peak molecular weight of 5000 An unmodified polyester (E1) was obtained.
200 parts of urea-modified polyester (U1) and 800 parts of unmodified polyester (E1) are dissolved and mixed in 2000 parts of a mixed solvent of ethyl acetate / MEK (1/1), and the binder resin (B1) ethyl acetate / MEK is mixed. A solution was obtained.
A part was dried under reduced pressure, and the binder resin (B1) was isolated. Tg was 62 ° C.

(Polyester resin synthesis example A)
Terephthalic acid 60 parts dodecenyl succinic anhydride 25 parts trimellitic anhydride 15 parts bisphenol A (2,2) propylene oxide 70 parts bisphenol A (2,2) ethylene oxide 50 parts And a 1 L four-necked round bottom flask equipped with a nitrogen gas introduction tube, this flask is set in a mantle heater, nitrogen gas is introduced from the nitrogen gas introduction tube, and the flask is kept under an inert atmosphere. Then, 0.05 g of dibutyltin oxide was added and reacted while maintaining the temperature at 200 ° C. to obtain polyester A.
This polyester A had a peak molecular weight of 4200 and a glass transition point of 59.4 ° C.
(Master batch creation example 1)
Pigment: Carbon black 40 parts Binder resin: Polyester resin A 60 parts Water 30 parts The above raw materials were mixed with a Henschel mixer to obtain a mixture in which water was soaked into the pigment aggregate. This was kneaded for 45 minutes with two rolls set at a roll surface temperature of 130 ° C., and pulverized to a size of 1 mmφ with a pulverizer to obtain a master batch (M1).

(Toner Production Example 3)
In a beaker, 240 parts of the above binder resin (B1) in ethyl acetate / MEK solution, 20 parts of pentaerythritol tetrabehenate (melting point: 81 ° C., melt viscosity: 25 cps), and 8 parts of master batch (M1) were added. The mixture was stirred at 12000 rpm with a TK homomixer at ° C, and uniformly dissolved and dispersed to prepare a toner material liquid.
In a beaker, 706 parts of ion exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved.
Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12000 rpm with a TK homomixer.
Next, this mixed solution was transferred to a Kolben equipped with a stir bar and a thermometer, heated to 98 ° C. to remove the solvent, filtered, washed, dried, and then classified by air to obtain toner particles.
Next, 100 parts of the toner particles were mixed with 0.5 part of hydrophobic silica and 0.5 part of hydrophobic titanium oxide using a Henschel mixer to obtain a toner (T3).

Next, the particle size of the toner (T3) was measured with a particle size measuring device “Coulter Counter TA2” manufactured by Coulter Electronics Co., Ltd., with an aperture diameter of 100 μm. The volume average diameter D4 = 5.2 μm and the number average diameter D1 = 4. D4 / D1 was 1.13 at .6 μm.
Subsequently, the circularity of the toner (T3) was measured as an average circularity by a flow type particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.). In the measurement, 0.1 to 0.5 ml of a surfactant (alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance, and a measurement sample is further added to 0.1 to 0.5 ml. About 0.5 g was added, and dispersion treatment was performed for about 1 to 3 minutes with an ultrasonic disperser, and a measurement liquid with a dispersion concentration adjusted to 3000 to 10,000 / μl was set.
The obtained toner (T3) had a circularity of 0.96.

Next, 920 parts of a carrier (weight average diameter D4 = 35 μm) obtained by applying a silicone coat to manganese ferrite magnetic particles and 80 parts of toner (T3) were mixed for 1 minute by a tumbler mixer to obtain a two-component developer. .
Each evaluation was performed in the same manner as in Example 1 except that the toner (T3) and the developer prepared with toner (T3) were used.

[Example 14]
(Toner Production Example 4)
The toner classification conditions in Toner Production Example 3 were adjusted, and the toner particle size distribution was changed to obtain a toner (T4) with D4 = 6.5 μm, D1 = 4.7 μm, and D4 / D1 = 1.38.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T4) and the developer prepared with toner (T4) were used.

[Example 15]
(Toner Production Example 5)
The toner classification conditions in Toner Production Example 3 were adjusted, and the toner particle size distribution was changed to obtain a toner (T5) with D4 = 6.0 μm, D1 = 4.1 μm, and D4 / D1 = 1.46.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T5) and the developer prepared with toner (T5) were used.

[Example 16]
(Toner Production Example 6)
The toner classification conditions in Toner Production Example 3 were adjusted, and the toner particle size distribution was changed to obtain a toner (T6) with D4 = 9.8 μm, D1 = 8.9 μm, and D4 / D1 = 1.10.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T6) and the developer prepared with toner (T6) were used.

[Example 17]
(Toner Production Example 7)
The toner classification conditions in Toner Production Example 3 were adjusted, and the toner particle size distribution was changed to obtain a toner (T7) with D4 = 3.1 μm, D1 = 2.7 μm, and D4 / D1 = 1.15.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T7) and the developer prepared with toner (T7) were used.

[Example 18]
(Toner Production Example 8)
A toner (T8) having D4 = 10.1 μm, D1 = 9.5 μm, and D4 / D1 = 1.06 was obtained by adjusting the air classification conditions in Toner Production Example 3 and changing the toner particle size distribution.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T8) and the developer prepared with toner (T8) were used.

[Example 19]
(Toner Production Example 9)
A toner (T9) having D4 = 2.7 μm, D1 = 2.5 μm, and D4 / D1 = 1.08 was obtained by adjusting the air classification conditions in Toner Production Example 3 and changing the toner particle size distribution.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T9) and the developer prepared with toner (T9) were used.

[Example 20]
(Toner Production Example 10)
The toner (T10) having a circularity SR = 0.93 was obtained by adjusting the liquid temperature, the rotational speed of the TK homomixer, and the stirring time in Toner Production Example 3 and changing the toner shape.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T10) and the developer prepared with toner (T10) were used.

[Example 21]
(Toner Production Example 11)
The toner (T11) having a circularity SR = 0.90 was obtained by adjusting the liquid temperature, the rotational speed of the TK homomixer, and the stirring time in Toner Production Example 3 and changing the toner shape.
Each evaluation was performed in the same manner as in Example 1 except that the toner (T11) and the developer prepared with toner (T11) were used.

[Example 22]
Each evaluation was performed in the same manner as in Example 1 except that the voltage applied to the charging device for charging the image bearing member was only a DC voltage of -600V.

[Example 23]
Using the charging roller (R1) and the toner (T3), a process cartridge in which an image carrier, a charging device, a developing device, and a toner container were integrated was prepared, and image evaluation was performed.
Since the toner in the container was completed at the running number of 25,000, the running test was continued by replacing the developer in the image carrier and the developing device and supplying the toner to the toner container.
When the image quality at the end of the use of the process cartridge was repeated five times, an image comparable to the initial one was obtained.
Finally, the running tests of Example 1 and Example 13 were continued up to a total of 1 million sheets, and an image that was comparable to the initial one was obtained.

As is clear from the comparison between each example and comparative example in Tables 1 to 3, by providing the coating layer on the surface of the charging member with a component having an affinity for the component of the toner, it is possible for a long time. It can be seen that the image quality can be maintained satisfactorily and the deterioration of the charging member and the image carrier can be suppressed.
In addition, the coating layer contains an electrically conductive substance, and the volume resistance of the charging member is set to 1 × 10 ³ Ω · cm to 1 × 10 ¹² Ω · cm, so that the image quality can be reliably improved over a long period of time. It can be understood that the charging member and the image carrier can be prevented from deteriorating while being maintained.
When using a polymerized toner having a small particle size and excellent transferability as described above, the amount of toner remaining on the image carrier is small, and adhesion of the toner to the charging member is not affected. Can be eliminated.

It is a principal part front view which shows the use condition of the charging device in embodiment of this invention. It is a general | schematic front view of a charging member. It is a general | schematic front view in the other example of a charging member. 1 is a schematic front view of a color copying machine as an image forming apparatus. It is a general | schematic front view of a process cartridge.

Explanation of symbols

1Y, 1M, 1C, 1K Photoconductor as image carrier 5 Transfer device 20 Charging roller 20c as charging member Surface coating layer as coating layer 25 Voltage application device 50 Intermediate transfer belt as intermediate transfer member 300 Process cartridge

Claims (20)

In a charging device having a charging member that is disposed in contact with or close to the surface of an image carrier that has undergone at least a step of carrying a toner image and charges the image carrier.
The charging device according to claim 1, wherein the charging member has a coating layer on the surface, and the coating layer has a component having an affinity for the toner component forming the toner image. In a charging device having a charging member that is disposed in contact with or close to the surface of an image carrier that has undergone at least a step of carrying a toner image and charges the image carrier.
A coating layer is formed on the surface of the charging member, and the toner remaining on the image carrier including the component having affinity for the toner component forming the toner image is adhered to the coating layer. A charging device characterized by imparting directivity to. The charging device according to claim 1 or 2,
A charging device, wherein the affinity component and the other components of the coating layer are incompatible. The charging device according to any one of claims 1 to 3,
The charging device according to claim 1, wherein the affinity component is the same as the resin component constituting the binder resin of the toner. The charging device according to any one of claims 1 to 4,
The charging device, wherein the coating layer contains an electrically conductive substance, and the charging member has a volume resistance of 1 × 10 ³ Ω · cm to 1 × 10 ¹² Ω · cm. The charging device according to any one of claims 1 to 5,
The charging device, wherein the content of the component having affinity is 10 to 40% by weight with respect to the total amount of the coating layer. The charging device according to any one of claims 1 to 5,
The charging device, wherein the component having affinity is at least one of a linear polyester resin composition, a linear polyol resin composition, a linear styrene acrylic resin composition, or a cross-linked product thereof. The charging device according to any one of claims 1 to 5,
A charging device, wherein the charging member has a hardness measured by an Asker C hardness meter of 20 to 90 degrees. An image carrier, a charging device that charges the image carrier, a latent image forming device that forms a latent image on the image carrier, and a development that visualizes the latent image on the image carrier as a toner image In an image forming apparatus having the apparatus,
An image forming apparatus, wherein the charging device is the charging device according to claim 1. The image forming apparatus according to claim 9.
An image forming apparatus comprising: a voltage applying device that applies a DC voltage or a voltage obtained by superimposing an AC voltage on a DC voltage to the charging device. The image forming apparatus according to claim 9 or 10,
An image forming apparatus comprising: a plurality of image carriers, and a transfer device that superimposes and transfers toner images on these image carriers onto a recording medium. The image forming apparatus according to claim 9 or 10,
A plurality of image carriers, and a transfer device for transferring the toner images on these image carriers onto an intermediate transfer member and transferring the superimposed image on the intermediate transfer member onto a recording medium. An image forming apparatus. The image forming apparatus according to any one of claims 9 to 12,
An image forming apparatus characterized in that the circularity SR of the toner represented by the following formula is 0.93 to 1.00.
Circularity SR = perimeter of a circle having the same area as the particle projection area / perimeter of the particle projection image The image forming apparatus according to any one of claims 9 to 12,
An image forming apparatus, wherein the toner has a weight average diameter D4 of 3 to 10 μm. The image forming apparatus according to any one of claims 9 to 12,
An image forming apparatus having a ratio (D4 / D1) of a weight average diameter D4 to a number average diameter D1 of toner of 1.00 to 1.40. At least an image carrier, a charging device that charges the image carrier, a latent image forming device that forms a latent image on the image carrier, and the latent image on the image carrier is visualized as a toner image. In a process cartridge integrally having a developing device,
9. A process cartridge, wherein the charging device is the charging device according to claim 1. The process cartridge according to claim 16, wherein
A process cartridge, wherein the toner represented by the following formula has a circularity SR of 0.93 to 1.00.
Circularity SR = perimeter of a circle having the same area as the particle projection area / perimeter of the particle projection image The process cartridge according to claim 16, wherein
A process cartridge having a toner weight average diameter D4 of 3 to 10 μm. The process cartridge according to claim 16, wherein
A process cartridge having a ratio (D4 / D1) of a weight average diameter D4 to a number average diameter D1 of toner of 1.00 to 1.40. In an image forming apparatus provided with a process cartridge detachably,
An image forming apparatus, wherein the process cartridge is the process cartridge according to any one of claims 16 to 19.

Images