JP2006078777A - Image forming apparatus and method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, having preferred transfer properties and cleaning properties, capable of forming sharp images of high image quality, without image defects, having superior retaining property and capable of stably forming a high-level color image of high image quality, and to provide a method for forming images. <P>SOLUTION: The image recording apparatus is equipped with at least a toner image forming means to form a toner image on an image-holding body; a transfer means for transferring the toner image onto a transfer body; a fixing means for fixing the transferred toner image to a recording medium; and a cleaning means for cleaning the residual toner by transfer on the image carrier. The toner used shows a dielectric loss factor in a range of 0.001 to 0.02, and a bias voltage is applied to a cleaning member in the cleaning means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image forming method for forming a toner image on an image carrier and transferring the toner image to a recording medium or an intermediate transfer member. Specifically, electrophotographic recording, electrostatic recording, etc. The present invention relates to an image forming apparatus and an image forming method for recording an image by the above method.

A method for visualizing image information through an electrostatic latent image such as electrophotography is currently used in various fields such as a copying machine and a printer with the development of the technology and the expansion of market demand.
In electrophotography, an electrostatic image is formed on a photoreceptor (image carrier) by charging and exposure processes, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process. . The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer using a magnetic toner or a nonmagnetic toner alone.

  Conventionally, since the production method of the toner is a kneading and pulverizing method, it is difficult to intentionally control the shape and surface structure of the toner, and often the generation of fine powder and the change of the toner shape are caused. Due to these effects, in the two-component developer, the charging deterioration of the developer is accelerated by the adhesion of fine powder to the carrier surface, and in the one-component developer, the toner scattering occurs due to the expansion of the particle size distribution, and the toner shape The deterioration in image quality was likely to occur due to a decrease in developability due to the change.

On the other hand, a toner production method using an emulsion polymerization aggregation method as a method for intentionally controlling the toner shape and the surface structure has been proposed (see, for example, Patent Documents 1 and 2).
In the emulsion polymerization aggregation method, since a finely divided raw material having a particle diameter of 1 μm or less is usually used as a starting material, a small-diameter toner can be efficiently produced in principle. More specifically, this method generally produces a resin dispersion by emulsion polymerization or the like, while producing a colorant dispersion in which a colorant is dispersed in a solvent, and mixes these resin dispersion and colorant dispersion. Then, aggregated particles corresponding to the toner particle diameter are formed, and then the aggregated particles are fused and united by heating to obtain a toner.

Usually, in such a toner production method, the surface and the interior of the obtained toner have the same composition, and it is difficult to intentionally control the surface composition. However, in order to solve this problem, a means to realize more precise particle structure control by freely controlling the toner from the inner layer to the surface layer when the toner is produced by the emulsion polymerization aggregation method is proposed. (See Patent Document 3).
The image quality of conventional electrophotographic images is dramatically improved by forming an image using the toner obtained by the toner production method capable of easily reducing the diameter of the toner and controlling the particle structure precisely. In addition, it has become possible to achieve both high reliability and high reliability.

  On the other hand, in recent years, the image forming method by electrophotography using the toner / developer technology as described above has begun to be applied to a part of the printing area due to the progress of digitization and colorization, and the on-demand printing has been started. Practical use in the graphic arts market is beginning to become remarkable.

  For example, in the short run printing market, technology targeting not only monochrome printing but also the short run color market represented by Fuji Xerox ColorDocuTech60 has been developed by taking advantage of the characteristics of plateless printing in electrophotography. A great progress is being made in terms of paper compatibility, product price, and price per sheet (see Non-Patent Document 1).

  However, plateless printing in electrophotography is typified by its color gamut, resolution, and gloss characteristics, although it has on-demand characteristics as plateless printing when compared to original full-scale conventional printing. Image quality, texture, image uniformity in the same image, maintainability of image quality during long continuous printing, high price per sheet due to toner consumption at high image density, compatibility with thinner and thicker paper, Image defects caused by oil during image fixing, poor writing performance, high power consumption due to high-temperature fixing at high speed, paper elongation, curl, wave, and registration marks on both sides due to image fixing at high temperature and pressure This is likely to cause problems.

In principle, a toner image composed of a low-molecular resin having a relatively low softening point is thermally fixed, so the heat and mechanical durability of the image may be weaker than the printed image. If the image is printed or bound in multiple layers and exposed to high temperatures under high load, it may cause problems with durability against various stresses such as image loss, blocking, offset, light resistance due to outdoor exposure, and weather resistance. May occur.
As described above, in order to meet the demands of the graphic arts market and the short run market (which may be called the light printing market), it is necessary to develop a technology that further develops the conventional electrophotographic technology as a system. ing.

  The reduction in the diameter of the toner is effective as a technology that meets the above-mentioned requirements in that a high-resolution image with high resolution can be obtained, the toner consumption can be reduced, and the price per sheet can be reduced. According to the emulsion polymerization aggregation method, it is possible to easily produce a toner having a small diameter of 5 μm or less, which is difficult to obtain by the conventional kneading and pulverizing method. However, the small-diameter toner is disadvantageous from the viewpoint of transferability and cleaning properties due to its high adhesion, and often causes a problem of reliability.

  Specifically, the transfer residual toner on the photoconductor or intermediate transfer body increases due to a decrease in transfer efficiency, or image density unevenness or image loss occurs due to deterioration in transferability to rough paper with low surface smoothness. It becomes easy to do. Also, in a cleaning system using a blade, sufficient cleaning cannot be performed due to abrasion from the blade, and image defects due to poor cleaning, background stains, streaks, and the like may occur. In particular, these deteriorations in image quality are often seen during continuous running.

  On the other hand, since the toner shape can be controlled according to the wet manufacturing method, it is possible to realize high transfer efficiency by making the toner shape spherical, thereby enabling high image quality by transferring the toner image more faithfully. From this point, the wet manufacturing method is effective as a technique that meets the above requirements. However, such a spherical toner also has a problem that it is difficult to clean with the blade cleaning system. Specifically, since it is spherical, it is easy to roll because it is easy to roll and there are few contact points, so it is easy to slip through by rolling or sliding in the contact area between the blade and the image carrier surface, and image defects due to poor cleaning etc. Likely to happen.

On the other hand, if the contact pressure of the blade against the image carrier is set to be large, the spherical toner can be cleaned initially, but the tip of the blade is subject to wear deterioration and early cleaning failure occurs. There is a problem that the surface of the image carrier is also easily worn and must be replaced at an early stage. In addition, since the cleaning system using a brush is fundamentally inferior to the blade system in cleaning performance, if a solid image with a coverage of nearly 100% passes through the transfer portion and reaches the cleaning portion due to paper jam or the like, the toner shape Regardless of whether you can clean enough.
Thus, the current situation is that there is no highly reliable cleaning system for spherical toner that has a high cleaning performance and that stably maintains the cleaning performance for a long period of time, which is a major problem in electrophotographic technology. .

  In principle, it is considered effective to use a cleaning system including a bias applying unit as a cleaning unit in order to ensure the cleaning performance for the small-diameter toner and the spherical toner. This is because small-sized toner and spherical toner cannot be cleaned satisfactorily only by the mechanical scraping force that acts at the time of cleaning. The idea is to clean effectively.

  As a cleaning system for applying the bias, for example, a method using a brush or a method using a blade has been proposed (see, for example, Patent Documents 4 and 5). The cleaning effect can be enhanced by applying and electrostatically attracting toner. As a bias application method, a method of applying an alternating voltage and a method of applying a bias voltage having the same polarity as the toner have been proposed (see, for example, Patent Documents 6 to 8).

  However, in any of the methods, when passing under a high electric field at the time of transfer, the charge of the toner is mutated by charge injection, and the toner remaining on the image carrier is hardly charged or has a reverse polarity. As a result, there has been a problem that the effect of the bias voltage cannot be fully exhibited. Furthermore, in the case of a conventional wet process toner, the charge distribution tends to become broad due to charge injection at the time of transfer, and a desired bias effect cannot be given to the small-diameter toner or spherical toner during cleaning.

  The reason why the above-mentioned wet process toner tends to have a broad charge distribution at the time of transfer is to control or maintain the toner particle diameter, although there is a slight difference between the surfactant and the dispersant (hereinafter referred to as “stabilizer”). This is thought to be due to the addition of For this reason, after the toner particles are usually formed by a wet process, a cleaning step for removing the stabilizer from the toner particles is performed.

  Many of the methods for removing the stabilizer from the toner particles are methods in which the toner particles are washed with water. For example, in water washing, 10 parts by mass of deionized water is added and stirred to obtain an electric charge of the solution. Although there is a method of setting the conductivity to 1 to 100 μS / cm (see, for example, Patent Document 9), it cannot be said that this method can define the stabilizer remaining in the vicinity of the surface and in the interior that affects the toner characteristics. Therefore, initially, excellent charging characteristics, dielectric characteristics, and fluidity can be obtained by the effect of the external additive on the toner surface. However, the external additive is peeled off from the toner particles during running of the actual machine, and the external surface in the concave portion of the toner surface. When the toner particles are deteriorated due to the burying of the additive, it is inevitable that the above characteristics are deteriorated.

  In addition to water cleaning, alkali cleaning may be performed (for example, see Patent Document 10). Certainly, the alkali increases the solubility of the stabilizer in the wash water, and the washability is expected to increase. However, as described above, the effect of removing the stabilizer remaining near and inside the toner surface is small. In addition, there is a problem that it is difficult to separate a large amount of stabilizer floating in the solution, and if it is attempted to reduce the stabilizer as much as possible, the amount of washing water required becomes enormous. Furthermore, in the emulsion polymerization aggregation toner or the like, the stabilizer remaining in the toner cannot theoretically be removed.

As described above, in order to meet the demands of the market, the small-diameter toner and spherical toner are indispensable. However, these toners are effectively and highly reliable in processes such as transfer and cleaning. There are still major technical challenges to use.
Japanese Patent Laid-Open No. 63-282275 JP-A-6-250439 Japanese Patent No. 3141784 Japanese Patent Publication No.42-16590 Japanese Patent Publication No. 45-25237 JP 56-167173 A JP-A-57-60363 JP 57-64279 A JP-A-7-319205 JP-A-5-142847 Journal of the Imaging Society of Japan Vol. 40 No. 2 (2001)

The object of the present invention is to solve the above-mentioned problems of the prior art.
That is, the object of the present invention is not only good transferability and cleanability, but also capable of forming clear high-quality images without image defects, as well as extremely excellent maintainability, stable high image quality and high quality. An object of the present invention is to provide an image forming apparatus and an image forming method capable of forming a color image.

  Said subject is achieved by the following this invention. As a result of intensive studies, the present inventors have reduced the residual stabilizer in the toner within a certain range and obtained a toner having a dielectric property kept at a certain value or less. As a result, it has been found that the toner remaining on the image carrier after transfer can be effectively removed by bias assist, and the present invention has been completed.

That is, the present invention
<1> At least a toner image forming unit that forms a toner image on an image carrier, a transfer unit that transfers the toner image to a transfer target, a fixing unit that fixes the transferred toner image on a recording medium, and an image In an image forming apparatus provided with a cleaning means for cleaning transfer residual toner on a carrier,
In the image forming apparatus, a toner having a dielectric loss ratio of 0.001 to 0.02 is used as the toner, and a bias is applied to a cleaning member in the cleaning unit.

<2> At least through an aggregation step in which the toner aggregates the particles in a dispersion in which particles containing at least resin particles are dispersed to obtain aggregated particles, and a fusion step in which the aggregated particles are heated to fuse. The image forming apparatus according to <1>, wherein the image forming apparatus is manufactured.

<3> The image forming apparatus according to <1> or <2>, wherein the toner has a volume average particle diameter in a range of 2 to 6 μm.

<4> The image forming apparatus according to any one of <1> to <3>, wherein a shape factor SF1 of the toner is in a range of 100 to 140.

<5> The image forming apparatus according to any one of <1> to <4>, wherein at least a blade is used as the cleaning member.

<6> The image forming apparatus according to any one of <1> to <5>, wherein at least a brush is used as the cleaning member.

<7> At least a toner image forming step for forming a toner image on an image carrier, a transfer step for transferring the toner image to a transfer target, a fixing step for fixing the transferred toner image to a recording medium, and an image In an image forming method including a cleaning step of cleaning a transfer residual toner on a carrier,
In the image forming method, the dielectric loss ratio of the toner is in a range of 0.001 to 0.02, and a bias is applied to the cleaning member in the cleaning step.

<8> At least through an aggregation step in which the toner aggregates the particles to obtain aggregate particles in a dispersion in which particles containing at least resin particles are dispersed, and a fusion step in which the aggregated particles are heated and fused. The image forming method according to <7>, wherein the image forming method is manufactured.

<9> The image forming method according to <7> or <8>, wherein the toner has a volume average particle diameter in the range of 2 to 6 μm.

<10> The image forming method according to any one of <7> to <9>, wherein a shape factor SF1 of the toner is in a range of 100 to 140.

<11> The image forming method according to any one of <7> to <10>, wherein at least a blade is used as the cleaning member.

<12> The image forming method according to any one of <7> to <11>, wherein at least a brush is used as the cleaning member.

  According to the present invention, not only the transferability and cleanability are good, but it is possible not only to form a clear high-quality image without image defects, but also extremely excellent maintainability, stable high-quality and high-quality color image. An image forming apparatus and an image forming method can be provided.

Hereinafter, the present invention will be described in detail.
<Image forming apparatus>
The image forming apparatus according to the present invention includes at least a toner image forming unit that forms a toner image on an image carrier, a transfer unit that transfers the toner image to a transfer target, and the transferred toner image is fixed to a recording medium. An image forming apparatus comprising a fixing unit and a cleaning unit for cleaning a transfer residual toner on an image carrier, wherein the cleaning unit uses a toner having a dielectric loss ratio of 0.001 to 0.02 as the toner. A bias is applied to the cleaning member.

  As described above, the residual stabilizer in the toner is reduced within a certain range, and the dielectric properties of the toner, specifically, the toner that maintains the dielectric loss rate corresponding to the resistance under an alternating electric field below a certain value As a result, it is found that excellent transfer characteristics can be obtained, and further, when such toner is applied to a cleaning system that removes toner remaining on the image carrier by bias assist after transfer, the cleaning characteristics are particularly excellent. The present invention has been completed.

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus of the present invention.
The image forming apparatus includes a drum-shaped image carrier 1 having a photosensitive layer on the surface, a charger 2 that uniformly charges the image carrier 1, and an image on the uniformly charged image carrier 1. An image writing device 3 that irradiates light to form an electrostatic latent image, and a developing unit 4 that accommodates four color developing devices of black (4a), yellow (4b), magenta (4c), and cyan (4d), respectively. (These are collectively referred to as toner image forming means), an endless belt-shaped intermediate transfer member (transferred member) 12 that is in contact with the image carrier 1 and is stretched around the image carrier 1, and the image carrier 1 A primary transfer roll 5 for transferring the toner image formed thereon to the intermediate transfer body 12, a cleaning device (cleaning means) 6 for removing toner remaining on the image carrier 1 after the transfer, and an endless belt-like intermediate transfer Drive roll for rotating the body 12 3 and tension rolls 14 and 15 for adjusting the tension of the endless belt-shaped intermediate transfer body 12, and the intermediate transfer onto the recording paper (transfer body) 8 conveyed by the conveyance roll 11 along the paper guides 9 and 10. A secondary transfer roll (transfer means) 17 for transferring a toner image on the body 12, a backup roll 16 provided opposite to the secondary transfer roll 17, and a toner on the recording paper 8 by the secondary transfer roll 17. A toner removing device 18 for removing toner remaining on the intermediate transfer body 12 after the image is transferred, and a fixing device (fixing means) 7 for fixing the toner image on the recording paper 8 are provided.

  The image carrier 1 is a function-separated type photoconductor in which a charge generation layer and a charge transport layer are sequentially laminated on a metal support (drum) such as aluminum, and the outer diameter of the photoconductor drum is 84 mm.

The charger 2 forms an elastic layer made of SBR (styrene-butadiene rubber) containing carbon on a metal core, and an ECO (epichlorohydride) containing an ionic conductive material as a resistance layer on the elastic layer. And a charging roll having a surface layer made of polyamide containing carbon black and SnO ₂ (conductive filler) formed thereon. The elastic layer has a thickness of 2.8 mm, the resistance layer has a thickness of 150 μm, the surface layer has a thickness of 10 μm, and the entire layer including the surface layer has a resistance value in the range of 10 ⁷ to 10 ⁸ Ω. The charger 2 applies a DC voltage to the cored bar to uniformly charge the surface of the image carrier 1. In addition to the contact-type charging roll, a non-contact-type charger such as a scorotron or a solid discharger may be used as the charger 2.

  The image writing device 3 repeatedly scans the laser beam of the light emitting element (LD) substantially perpendicularly to the rotation direction (arrow A) of the image carrier 1, and rotates by turning this light emitting element on / off based on the image signal. Image exposure is performed on the driven image carrier 1.

  The four developing devices 4a, 4b, 4c, and 4d in the developing unit 4 are supported by a single base 4e that is rotationally driven, and sequentially approach and face the image carrier 1, so that each color is The toner is transferred to the corresponding latent image and visualized to form a toner image. A detailed description of the developer used in the developing unit 4 will be given later.

The intermediate transfer body 12 is obtained by dispersing carbon black in a polyimide resin to form an endless belt having a thickness of 80 μm. The volume resistivity of the belt was 10 ⁹ Ωcm, and the surface resistivity was 10 ¹² Ω / □.

The primary transfer roll 5 is formed by forming a urethane foam layer on a metal core, and the resistance value of the roll is adjusted to 10 ⁸ Ω. The outer diameter of the primary transfer roll 5 was 18.5 mm.
In addition, the roll resistance value in the image forming apparatus including the primary transfer roll is set such that each roll is placed on a metal plate connected to the ground, and a load of 500 g in total is applied to both ends of the roll. A DC voltage of 1 kV was applied between the values and converted from the measured current value.

The secondary transfer roll 17 has a two-layer structure with an outer diameter of 28 mm, and has a thin surface layer having high resistance and an elastic layer having elasticity with resistance lower than that of the surface layer inside thereof. The surface layer has a volume resistivity in the range of 10 ⁸ to 10 ¹³ Ωcm, the resistance of the elastic layer is lower than the resistance of the surface layer, and the resistance value of the entire roll is adjusted to a range of 10 ⁸ to 10 ⁹ Ω. It is.

The toner removing device 18 is a brush having an outer diameter of 17.5 mm manufactured by winding a woven fabric in which a nylon fiber is woven around a metal core, the fiber thickness is 0.67 tex (6 denier), and the pile length Is 5.5 mm, and the amount of biting into the intermediate transfer member is set to about 1 mm. The toner and paper dust are removed by rotating in the direction opposite to the conveyance direction of the intermediate transfer belt (arrow B). A flicker bar 19 is in contact with the brush so as to scrape off toner adhering to the brush fibers. The flicker bar 19 is coated with a fluororesin to prevent toner and the like from adhering to and accumulating on the surface of the flicker bar.
The fixing device 7 fixes the toner image transferred onto the recording paper 8 to form a recorded image.

Next, the cleaning device 6 will be described below.
A configuration example of the cleaning device 6 is shown in FIG. The cleaning device 6 includes a cleaner housing 24 that is disposed in the vicinity of the image carrier 1 and opens to the side facing the image carrier 1. A seal member 25 is fixed to the lower opening end of the cleaner housing 24. The seal member 25 substantially closes the gap between the image carrier 1 and the cleaning device 6 and prevents waste toner or the like in the cleaning device 6 from leaking to the outside. In this example, a thermoplastic polyurethane film having a thickness of 0.2 mm was used as the seal member 25.

  In the cleaning device 6, a cleaning blade 20 whose tip is in contact with the surface of the image carrier is disposed as a cleaning member downstream of the seal member 25 in the rotation direction (arrow) of the image carrier 1. For the blade material, thermosetting urethane rubber with excellent mechanical properties such as wear resistance, chipping resistance, and creep resistance is used. In the present invention, conductivity is imparted to bias the cleaning blade. Yes. For imparting conductivity, a method of dispersing a conductive agent in this urethane rubber is usually employed.

  The cleaning blade 20 is bonded to a sheet metal 21 having an L-shaped cross section, and is fixed to the cleaner housing 24 by a set screw 22. Bias application to the cleaning blade 20 is performed by a bias application means 26. In addition, an auger 23 is disposed in the lower part of the cleaning device 6, and waste toner is discharged out of the cleaning device 6 by the auger 23.

  The configuration of the cleaning blade 20 includes a single layer type composed of layers of the same material type and a multilayer type composed of layers of different material types. The multilayer type has, for example, a two-layer structure as shown in FIG. 3, and includes a first layer 20a on the side that directly contacts the surface of the image carrier and a second layer 20b on the back side. The first layer 20a is a semiconductive layer using an ionic conductive agent as a conductive agent, and the second layer 20b is a conductive layer using an electronic conductive agent as a conductive agent.

As specific materials, an alkali metal salt is used for the ionic conductive agent, the volume resistivity is adjusted to a range of 10 ⁸ to 10 ⁹ Ωcm, and a carbon black is used for the electronic conductive agent, and the volume resistivity is 10 ^5. It is adjusted to the range of -10 ⁶ Ωcm. As the conductive agent, in addition to carbon black, metal (Cu, Al, Ni, Ag, etc.), metal oxide, graphite, conductive polymer, etc. are used as the electron conductive agent, and sodium, In addition to alkali metal salts such as potassium and lithium, alkaline earth metal salts, quaternary ammonium salts, bromides, nitrites, sulfates, perchlorates and the like are used.

The reason why the cleaning blade has a two-layer structure of a semiconductive layer and a conductive layer is as follows.
If the urethane rubber layer in which the electron conductive agent is dispersed is provided on the side in contact with the surface of the image carrier, the electron conductive agent is not exposed (appears) on the contact surface, and blade edge chipping is likely to occur. This phenomenon is likely to occur due to wear of the blade contact surface due to friction between the blade edge and the surface of the image carrier. As a result, there is a problem that cleaning failure tends to occur at an early stage, which is not practical. On the other hand, when only the ionic conductive agent is dispersed and conductivity is imparted, the amount of the ionic conductive agent is increased for the purpose of obtaining the desired volume resistivity (10 ⁵ to 10 ⁶ Ωcm). As a result, there arises a problem that the photoreceptor is liable to be contaminated by the leaching of the ionic conductive agent. Therefore, the volume resistivity must be in the range of 10 ⁸ to 10 ⁹ Ωcm. Therefore, a semiconductive layer using an ionic conductive agent as a conductive agent is provided on the side in contact with the surface of the image bearing member, and a conductive layer using an electron conductive agent capable of imparting desired conductivity is provided on the back side of the image carrier. It was set as the 2 layer structure which can make resistance value compatible. The semiconductive layer is preferably made as thin as possible in order to efficiently apply a bias, and is set to a range of 0.05 to 0.5 mm. In this example, the semiconductive layer was 0.01 mm, and the blade thickness including the semiconductive layer and the conductive layer was 2 mm.

As shown in FIG. 4, the single layer type is composed of the layer 20c of the same material type, and for example, a so-called hybrid material in which an electron conductive agent and an ionic conductive agent are mixed is used. By using an electron conductive agent and an ionic conductive agent in combination, desired conductivity can be obtained even if the content of the electronic conductive agent is reduced, and the variation in resistivity due to non-uniform dispersion of the electronic conductive agent is suppressed. It is something that can be done. As a specific material, carbon black is used as an electron conductive agent, and an alkali metal salt is used as an ionic conductive agent to obtain a blade having a thickness of 2 mm and a volume resistivity of 10 ⁵ to 10 ⁶ Ωcm. it can.

  Note that the blade pressurization method in this example uses a constant displacement method with a simple structure and low cost, and the specific pressure is set to 1.96 N / m (2 gf / cm). However, the blade pressing method is not limited to the constant displacement method, and a constant load method in which the contact pressure hardly changes with time may be used.

In the present invention, a brush can be used as the cleaning member.
FIG. 5 shows a case where a conductive brush 27 is used in the cleaning device 6 in place of the conductive blade. 28 is an auger, 29 is a cleaner housing, 30 is an upper seal member, and 31 is a lower seal member. , 32 are bias applying means. Even when the conductive brush 27 is used, good cleaning can be performed by utilizing the bias effect. Note that it is preferable to use the conductive brush by rotating it in the direction opposite to that of the image carrier 1 because the scraping power is increased.

  FIG. 6 shows a case where the magnetic brush 33 is used in the cleaning device 6, wherein 34 is a rotating sleeve, 35 is a fixed mag roll, 36 is an auger, 37 is a cleaner housing, 38 is an upper seal member, and 39 is a lower seal member. , 40 is a bias applying means. Even when the magnetic brush 33 is used, the bias effect can be exerted in the same manner. Since the scraping force is increased as compared with the brush, there is a merit that the scraping effect of discharge products and the like is increased. In this case, like the conductive brush, the scraping force is further increased by rotating the image carrier 1 in the opposite direction.

  FIG. 7 shows a case where the conductive blade 41 and the conductive brush 44 are used together in the cleaning device 6, 42 is a sheet metal, 43 is a set screw, 44 is a conductive brush, 45 is an auger, 46. Is a cleaner housing, 47 is a seal member, and 48 and 49 are bias applying means. By using a blade and a brush in combination, the cleaning performance is further improved than when used alone. In this case, in order to effectively use the bias effect, it is preferable to apply a bias having the same polarity as that of the toner to one of the brush or the blade and to apply a bias having a polarity opposite to that of the toner to the other.

As mentioned above, although the aspect which can be taken as the cleaning means in the present invention has been shown, in the present invention, it is most preferable to use the cleaning device including the brush and the blade shown in FIG. Next, it is preferable to use a cleaning device having a blade shown in FIGS. 2 to 4, and then to use a cleaning device having a brush shown in FIG. 5.
The voltage applied by the bias applying means is preferably in the range of 200 to 2000 V as a DC voltage.

Next, the developer used in the developing unit 4 will be described in detail below.
In the present invention, the dielectric loss factor of the toner contained in the developer needs to be in the range of 0.001 to 0.02. The dielectric loss factor of the toner obtained by the conventional wet method exceeds 0.02 and is high. This dielectric loss factor represents the resistance of a dielectric placed under an alternating electric field, and it is known that the resistance decreases as the value increases. When the toner resistance is low, it is considered that the charge amount or charge distribution of the toner is likely to change.

  As a result of intensive studies by the present inventors, the toner in the toner image on the image carrier after development can be obtained by setting the dielectric loss factor (also referred to as relative dielectric loss factor) of the toner to a range of 0.001 to 0.02. Alternatively, the charge amount of the transfer residual toner after transfer is stable, and even with a small particle size and spherical toner produced by a wet method, high transfer efficiency and good cleaning system with bias application It was found that cleaning characteristics can be obtained.

  The dielectric loss factor is preferably in the range of 0.005 to 0.015, and more preferably in the range of 0.01 to 0.012. When the dielectric loss ratio exceeds 0.02, the charge amount of the toner on the image carrier becomes unstable, and transferability and cleaning performance deteriorate. Especially in a system that reuses cleaning toner and a cleanerless system for a long time. Crossing reliability cannot be ensured. Also, practically no toner less than 0.001 can be produced.

The dielectric loss factor is measured by, for example, molding toner powder into a tablet, placing it on a dielectric measurement electrode, and applying an alternating electric field up to 100 kHz. A specific method for measuring the dielectric loss factor of the toner is as follows. That is, 5 g of toner is formed into a pellet, set between electrodes [SE-71 type solid electrode, manufactured by Ando Electric Co., Ltd.], and the conductivity is measured at 5 V with an LCR meter (4274A type, manufactured by Yokogawa Hewlett Packard). And it calculates | requires by following formula (1).
Dielectric loss factor = [14.39 / (W × D ² )] × G _X × T _X × 10 ¹² Formula (1)
(W = 2πf (f: measurement frequency 100 kHz), D: electrode diameter (cm), G _X : conductivity of sample (S), T _X : sample thickness (cm))

The toner in the present invention is manufactured as follows.
The toner particles are produced by an emulsion polymerization aggregation method or the like, and are formed by aggregation / aggregation and granulation while stirring in a dispersion in which resin particles and a colorant are dispersed. In addition to the resin particles and the colorant, inorganic fine particles, release agent fine particles, charge control agent fine particles and the like can be added as necessary. It is desirable to add and mix these fine particle dispersions in a plurality of times.

  In the production of toner particles, at least a first step of forming aggregated particles in a dispersion in which resin particles are dispersed to prepare an aggregated particle dispersion, and fine particles in which fine particles are dispersed in the aggregated particle dispersion It is desirable to have a second step of adding and mixing the dispersion to adhere the fine particles to the aggregated particles to form the adhered particles, and a third step of heating and fusing the adhered particles.

The second step is preferably performed a plurality of times. In this second step, a release agent fine particle dispersion obtained by dispersing release agent fine particles is added to and mixed with the aggregated particle dispersion to form the attached particles by attaching the release agent fine particles to the aggregated particles. Then, it is preferable to add and mix a resin-containing fine particle dispersion in which resin-containing fine particles are dispersed to further adhere the resin-containing fine particles to the adhered particles to form the adhered particles.
In the second step, a colorant fine particle dispersion in which colorant fine particles are dispersed is added to and mixed with the resin fine particle agglomerated particle dispersion to adhere the colorant fine particles to the aggregated particles, thereby attaching the adhered particles. After the formation, it is preferable to add and mix a resin-containing fine particle dispersion in which resin-containing fine particles are dispersed to further adhere the resin-containing fine particles to the adhered particles to form the adhered particles.

  Further, in the second step, after the resin-containing fine particle dispersion obtained by dispersing the resin-containing fine particles is added and mixed in the aggregated particle dispersion, the resin-containing fine particles are adhered to the aggregated particles to form the adhered particles. It is preferable to add and mix an inorganic fine particle dispersion in which inorganic fine particles are dispersed to further adhere the inorganic fine particles to the adhered particles to form the adhered particles.

In the second step, the fine particle dispersion is added to and mixed with the aggregated particle dispersion prepared in the first step, and the fine particles are adhered to the aggregated particles to form adhered particles. The fine particles correspond to newly added particles as viewed from the aggregated particles, and may be referred to as “additional particles”.
The method for adding and mixing the fine particle dispersion is not particularly limited. For example, the fine particle dispersion may be gradually and continuously performed, or may be divided into a plurality of steps and performed stepwise. Thus, by adding and mixing the fine particles (additional particles), generation of fine particles can be suppressed, and the particle size distribution of the toner particles obtained can be sharpened. In addition, when the addition and mixing is performed stepwise by dividing into a plurality of times, a layer of the fine particles is layered stepwise on the surface of the aggregated particles, and a structural change or a composition gradient may be given from the inside to the outside of the toner particles. In addition, the surface hardness of the particles can be improved, and the particle size distribution can be maintained and the fluctuation can be suppressed during the fusion in the third step, and the surfactant for enhancing the stability during the fusion. It is advantageous in that the addition of a stabilizer such as water or a base or an acid can be made unnecessary or the amount thereof can be suppressed to the minimum, and the cost can be reduced and the quality can be improved.

  Examples of the resin used for the resin particles include styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, and 2-ethylhexyl acrylate. , Esters having a vinyl group such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinyl methyl ether, vinyl isobutyl Polymers such as monomers such as vinyl ethers such as ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; polyolefins such as ethylene, propylene and butadiene; A copolymer obtained by combining two or more of these, or a mixture thereof, and further, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, and the like, a non-vinyl condensation resin, or these and the vinyl resin Examples thereof include a mixture with a resin and a graft polymer obtained when a vinyl monomer is polymerized in the presence of these.

  The resin particle dispersion is formed by dispersing the above resin in water so as to have a concentration of 2 to 40% by mass. The volume average particle size of the dispersed resin particles is preferably 1 μm or less, and more preferably 0. The range is from 0.01 to 1 μm. When the volume average particle size of the resin particles exceeds 1 μm, the particle size distribution of the finally obtained toner becomes wider or free particles are generated, which leads to a decrease in performance and reliability. On the other hand, if the volume average particle size of the resin particles is within the above range, the above disadvantages are eliminated, uneven distribution among the toners is reduced, dispersion in the toners is improved, and variations in performance and reliability are reduced. Is advantageous. The volume average particle diameter of the resin particles can be measured using, for example, a Coulter counter.

  In the case of the vinyl monomer, an emulsion polymerization or seed polymerization can be carried out using an ionic surfactant or the like to prepare a resin particle dispersion. In the case of other resins, the resin is oily and water. If it is soluble in a solvent with relatively low solubility in the resin, dissolve the resin in those solvents, disperse the particles in water together with ionic surfactants and polymer electrolytes with a disperser such as a homogenizer, and then heat Alternatively, the resin particle dispersion can be produced by evaporating the solvent under reduced pressure.

  Examples of colorants include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, resol red, rhodamine B rake, lake red C, rose bengal, aniline blue, ultramarine blue, calco rose ben oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate, etc. Various pigments, acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thio Colorants such as various dyes such as Ndigo, Dioxazine, Thiazine, Azomethine, Indigo, Phthalocyanine, Aniline Black, Polymethine, Triphenylmethane, Diphenylmethane, Thiazine, Thiazole, Xanthene One or more types can be used in combination.

  The colorant dispersion is prepared by adding the above-mentioned colorant to a concentration of 2 to 40% by mass in water, using an ionic surfactant having a polarity opposite to that of the resin used, a rotary shearing homogenizer, a ball mill, It can be produced by a known dispersing device such as a sand mill or a dyno mill. The volume average particle diameter of the colorant is preferably in the range of 0.05 to 0.50 μm by a measuring instrument such as a scattering type particle size distribution measuring instrument (manufactured by HORIBA, LA700).

  In the present invention, an internal additive may be added when the resin particle dispersion and the colorant dispersion are mixed. As the internal additive, a magnetic material such as a metal such as ferrite, magnetite, reduced iron, cobalt, nickel, manganese, an alloy, or a compound containing these metals can be used.

  In addition, as the charge control agent, various commonly used charge control agents such as quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments can be used. A material that is difficult to dissolve in water is preferably used in terms of controlling ionic strength that affects the stability during aggregation and aggregation and reducing wastewater contamination.

  Further, it is preferable to add a release agent fine particle dispersion when mixing the resin particle dispersion and the colorant dispersion. Examples of mold release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene, silicones having a softening point upon heating, fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide and the like. Plant wax such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, animal wax such as beeswax, montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch Minerals such as waxes, petroleum-based waxes, and modified products thereof can be used.

  These waxes are dispersed in water together with ionic surfactants, polymer electrolytes such as polymer acids and polymer bases, and heated with a homogenizer or pressure discharge type disperser that can be heated to the melting point or higher and subjected to strong shearing. And can be added as a dispersion of particles having a volume average particle diameter of 1 μm or less.

  The resin particle dispersion and the colorant dispersion, and if necessary, other components are mixed at a predetermined ratio, and the resin particles and the colorant are aggregated by heating in a range from room temperature to the glass transition temperature of the resin particles. , Forming aggregated particles. The volume average particle diameter of the aggregate fine particles is preferably in the range of 2 to 6 μm. Next, a toner particle-containing liquid (toner particle dispersion) containing toner particles by heat-treating the mixed liquid containing the aggregated particles at a temperature equal to or higher than the softening point of the resin, generally 70 to 120 ° C. Can be obtained.

  Examples of surfactants used for emulsion polymerization, seed polymerization, pigment dispersion, resin particles, release agent dispersion, aggregation, or stabilization thereof include sulfate ester, sulfonate, and phosphate ester types. , Soap type anionic surfactants, amine salt type, quaternary ammonium salt type cationic surfactants, polyethylene glycol type, alkylphenol ethylene oxide adduct type, polyhydric alcohol type nonionic surface active It is also effective to use an agent in combination, and general means such as a rotary shear homogenizer, a ball mill having a media, a sand mill, and a dyno mill can be used for dispersion.

Next, the obtained toner particle-containing liquid is separated into toner particles by centrifugal separation or suction filtration, and washed with ion exchange water 1 to 3 times. The dielectric loss factor of the toner depends on the remaining amount of the stabilizer in the toner during the cleaning process.
The amount of residual stabilizer in the toner can be measured as follows. That is, after dissolving the toner in 1 to 10 parts by mass of an organic solvent, about 10 to 100 parts by mass of deionized water is added to this solution. Since the residual stabilizer can be extracted into an aqueous layer or an oil layer, the amount of residual stabilizer can be measured by measuring the electrical conductivity and surface tension of the extract. As the organic solvent, generally known ones can be used regardless of the polarity.

  After the toner particles used in the present invention are washed with water as described above, the toner particles are dispersed again in the washing water and heated to the glass transition temperature (Tg) or higher of the resin constituting the toner particles and stirred. A cleaning method is used. As a result, the toner particles after washing are dissolved in an organic solvent, and then the electric conductivity and surface tension of the solution when mixed with deionized water can be controlled to a certain range.

  More specifically, after the toner particles are dispersed again in ion-exchanged water, the toner particles are heated to a temperature higher than the glass transition temperature (Tg) of the resin constituting the toner particles and stirred for about 30 minutes to 2 hours. Then, after cooling to room temperature, the toner particles are again filtered, washed with ion-exchanged water about 1 to 5 times, and dried, whereby the toner particles in the present invention can be obtained.

  When heating to a temperature higher than the glass transition temperature (Tg) of the resin constituting the toner particles, if the temperature is too high, the colorant and release agent in the toner particles are easily released during production, and the charging property and dielectric properties are improved. If the temperature is less than Tg, the effect of extracting the stabilizer remaining inside is small, and it becomes difficult to obtain good chargeability and dielectric properties. It is desirable to heat it.

  Further, it is desirable to adjust the pH of the toner particle-containing liquid (toner particle dispersion) before the heating step to a range of 7 to 12 and stir. When the pH of the toner particle-containing liquid (toner particle dispersion) is lower than 7, the extraction of the stabilizer is likely to be insufficient, and the generation of low-charged toner and the stability at high temperatures are likely to be reduced. It is remarkable in the toner which has. On the other hand, if it is higher than 12, the alkali tends to remain and the charging characteristics tend to be insufficient.

  The electric conductivity of the toner particles thus obtained is preferably 100 μS / cm or less, more preferably 50 μS / cm or less, and further preferably 20 μS / cm or less. Further, the surface tension of the solution is preferably 30 mN or more, more preferably 40 mN or more, and further preferably 50 mN or more.

  When the electric conductivity is higher than 100 μS / cm, and when the surface tension is lower than 20 mN, the resistance of the toner is lowered, and it becomes difficult to make the dielectric loss ratio of the toner fall within the range specified in the present invention. In addition, there is a case where fogging, scattering, etc. are caused by charging failure particularly under high temperature and high humidity, resulting in deterioration of image quality.

  8 and 9 show the relationship between the electrical conductivity, surface tension and charging characteristics of the toner particles. In FIGS. 8 and 9, ● is a plot of toner particles obtained by a conventional cleaning method when toner particles are produced by a wet manufacturing method, and ■ is a cleaning according to the present invention when toner particles are produced by a wet manufacturing method. 2 is a plot for toner particles obtained by the method. The “charge level” on the vertical axis indicates the toner concentration and the carrier concentration of 8% when the toner and the carrier are left in an environment of 28 ° C. and 80% RH for 24 hours using a CSG (charge spectrograph) measuring device described later. In the same environment, it is placed in a glass bottle and stirred for 2 minutes with a turbula mixer (120 rpm), and the distance from the baseline of the peak portion of the charge amount distribution of each toner observed by measurement is shown. The baseline is a measured value when the voltage of the CSG measuring device is set to 0V.

  Here, the conventional cleaning method is a case where toner particles are obtained by washing the toner particle dispersion with water, and the cleaning method in the present invention is a method of washing the toner particles again after washing the toner particle dispersion with water. This is a case where the toner particles are dispersed in water and then the toner particles are heated to Tg or more, and are substantially the same as the other conditions.

  As shown in FIG. 8, the toner particles obtained by the cleaning method of the present invention have a lower electrical conductivity and a higher charge level than the toner particles obtained by the conventional cleaning method. Further, as shown in FIG. 9, the toner particles obtained by the cleaning method of the present invention have a higher surface tension and a higher charge level than the toner particles obtained by the conventional cleaning method. Therefore, the toner particles obtained by the cleaning method of the present invention have higher charging characteristics than the toner particles obtained by the conventional cleaning method.

  In the study by the present inventors, among the toners obtained by the cleaning method of the present invention, at least the electric conductivity is in the range of about 25 to 30 μS / cm and the surface tension is in the range of about 32 to 44 mN. As a result, it has been found that the final dielectric loss factor of the toner can be in the range of 0.001 to 0.02.

  The toner particles finally obtained by heating as described above include inorganic particles such as silica, alumina, titania and calcium carbonate, and resin fine particles such as vinyl resin, polyester and silicone in a dry state. And added to the surface as a fluidity aid or cleaning aid.

The toner used in the present invention preferably has a volume average particle diameter D _50v in the range of _2.0 to 6.0 μm. The volume average particle size is more preferably in the range of 2.0 to 4.0 μm. When the volume average particle diameter of the toner exceeds 6.0 μm, the ratio of coarse particles increases, and the reproducibility and gradation of fine lines and fine dots of an image obtained through the fixing process are deteriorated. On the other hand, when the volume average particle size of the toner is less than 2.0 μm, the powder fluidity, developability, or transferability of the toner deteriorates, and the cleaning property of the toner remaining on the surface of the image carrier decreases. Various problems occur in other processes due to the deterioration of powder characteristics.

The volume particle size distribution index GSDv of the toner in the present invention is preferably 1.3 or less, and more preferably 1.25 or less. The number particle size distribution index GSDp is preferably 1.3 or less, and more preferably 1.25 or less.
If GSDv is greater than 1.3, it indicates that there is a lot of coarse powder in the toner, and image scattering may occur. When GSDp is larger than 1.4, it indicates that the amount of fine powder in the toner is large, and there is a case where toner contamination in the apparatus due to toner scattering increases.

The volume average particle diameter, GSDv, and GSDp are determined as follows. First, for example, based on the particle size distribution measured by a measuring instrument such as Coulter Counter TAII (manufactured by Beckman-Coulter), the volume and number are each subtracted from the small particle size side, and the cumulative 16% particle size volume D _16v made, the number D _16p, 50% accumulation become volume particle diameter D50v (this is the volume average particle diameter), the number D _50p, 84% accumulation becomes volume particle diameter D _84v, number D _84p is defined.
The volume particle size distribution index GSDv is calculated as (D _84v / D _16v ) ^1/2 , and the number average particle size distribution index GSDp is calculated as (D _84p / D _16p ) ^1/2 .

Furthermore, the toner shape factor SF1 in the present invention is preferably in the range of 100 to 140. When the shape factor is larger than 140, the transferability is deteriorated. In particular, the closer the shape is to a sphere (true sphere), the more difficult it is to remove the stabilizer by simply cleaning the surface with normal water or alkali, which has an adverse effect on charging properties, and a decrease in image density. Although it is not preferable in use, the toner in the present invention can achieve stable charging characteristics even when the shape is spherical. Deterioration of the developer is promoted by lowering the fluidity of the toner and applying a strong partial stress or increasing the conveyance force and stirring force.
The SF1 is more preferably in the range of 100 to 125.

Here, the shape factor SF1 is obtained by the following equation (2).
SF1 = (ML ² / A) × (π / 4) × 100 (2)
In the above formula (2), ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.

  The SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and can be calculated as follows, for example. That is, an optical microscope image of the toner scattered on the surface of the slide glass is taken into a Luzex image analyzer through a video camera, the maximum length and projected area of 100 or more toner particles are obtained, calculated by the above equation (2), and the average Obtained by determining the value.

Next, the operation of the image forming apparatus of the present invention will be described with reference to FIG.
A drum-shaped image carrier (photosensitive drum) 1 is driven to rotate and is uniformly charged to about −700 V by a charger 2. Image light is irradiated at a position facing the image writing device 3, and the charge of the photosensitive layer of the image carrier 1 is reduced by exposure to about −300 V, and a latent image is formed due to a difference in electrostatic potential.

  This latent image moves to a position facing the developing unit 4. A developing bias in which an AC component having an amplitude (Peak to Peak) of 1.0 kV, a frequency of 9.0 kHz, and a duty of 0.6 is applied to the developing roller of each developing device of the developing unit 4 is applied to a −550 V DC component. Yes. Thereby, the black toner transferred from the developing roll is first attached, and the latent image is visualized. The black toner image thus formed is primarily transferred onto the intermediate transfer body 12 by the primary transfer roll 5 to which a bias voltage is applied. The toner remaining on the image carrier 1 after the primary transfer is removed by the cleaning device 6.

  In the image carrier 1, for each color of yellow, magenta, and cyan, charging by the charger 2, irradiation of image light by the image writing device 3, formation of a toner image by the developing unit 4, intermediate transfer by the primary transfer roll 5 Each step of transfer to the body 12 is repeated, and as a result, a color image in which toner images of four colors are superimposed on the intermediate transfer body 12 is formed.

  The color image is secondarily transferred onto the recording paper 8 by the secondary transfer roll 17 at once. The toner remaining on the intermediate transfer body 12 after the secondary transfer is removed from the intermediate transfer body 12 by the toner removing device 18. Finally, the image is fixed by the fixing device 7 to obtain a recorded image.

In the present invention, by setting the dielectric loss factor of the toner to 0.02 or less, high transferability and good cleaning properties can be obtained. This point will be described more specifically.
FIG. 10 shows the relationship between the dielectric loss rate of toner and the transfer efficiency. The transfer efficiency was measured using a modified Able1302 machine manufactured by Fuji Xerox Co., Ltd., using a toner having a volume average particle size of 4.0 μm and a shape factor SF1 of 122.

  From the correlation between the dielectric loss factor and the transfer efficiency in the toner shown in FIG. 10, it can be seen that the transfer efficiency is high when the dielectric loss factor is low. The transfer efficiency here represents the ratio of the reflection density of the developed toner image on the photoreceptor and the untransferred residual image, and indicates the transfer efficiency when the developed toner image density is 0.7. Yes. From this figure, it can be seen that in order to achieve a transfer efficiency of 95% or more, the dielectric loss factor of the toner needs to be 0.02 or less.

Next, operations related to cleaning in the present invention will be described.
The cleaning means in the present invention effectively uses a bias applying means. Therefore, in the wet process toner to be used, it is necessary that the toner charge amount is stable after development on the photoreceptor and further after transfer. In the present invention, it has been found that by setting the dielectric loss factor of the toner to 0.02 or less, charge injection hardly occurs even under a high electric field during transfer, and the toner charge hardly changes.

  Therefore, the charge of the toner remaining on the surface of the photosensitive drum after the transfer retains the charge before the transfer, and can effectively impart a bias action to the toner during cleaning. As a result, even a small-diameter toner or a spherical toner, which has conventionally been difficult to clean, can be satisfactorily cleaned. Note that the fact that the toner charge hardly changes during transfer means that the toner is effectively moved by the transfer electric field, whereby high transfer efficiency can be obtained as described above.

  A specific cleaning operation is as follows. In FIG. 2, an appropriate bias is applied to the blade 20 from the bias applying means 26. For example, by applying a positive bias voltage having a polarity opposite to that of the toner, an attractive force is exerted on the toner and trapped at the blade tip, so even a small-diameter toner or a spherical toner can be used in the contact area between the blade and the photoreceptor. It is possible to prevent slipping through. In general, the smaller the amount of toner that enters the contact area, the less likely that slip-through occurs. When a voltage having a polarity opposite to that of the toner is applied, before the toner reaches the contact area between the blade and the photoconductor. In addition, the electric field generated by the difference between the blade end surface potential and the photoreceptor surface potential causes the toner to fly to the blade end surface, and the toner reaching the contact area is substantially reduced. .

  On the other hand, when a negative bias voltage having the same polarity as that of the toner is applied, a repulsive force acts on the toner. In this case, the amount of toner entering the contact area can be reduced more than in the case of applying the reverse polarity. Therefore, even small-diameter toner and spherical toner are cleaned with the mechanical scraping force of the blade. At this time, the scraping force is known to increase as the rebound resilience of the rubber material of the blade increases. As a result of separate examination, it is necessary to use a rubber material having a rebound resilience of about 50% from a low temperature to a high temperature. preferable.

  As described above, when the toner according to the present invention is used, the toner charge amount is maintained even after the transfer, so that the bias effect works effectively at any bias voltage, and the small diameter toner and the spherical toner are well cleaned. It becomes possible to do.

  The developer used in the present invention can be obtained by combining the toner with a carrier. The carrier is not particularly limited, and examples thereof include known carriers. The mixing ratio of the toner in the present invention and the carrier in the developer is not particularly limited and can be appropriately selected depending on the purpose.

<Image forming method>
The image forming method of the present invention includes at least a toner image forming step for forming a toner image on an image carrier, a transfer step for transferring the toner image to a transfer target, and fixing the transferred toner image on a recording medium. There is no particular limitation as long as it has a fixing step and a cleaning step for cleaning the transfer residual toner on the image carrier, and the toner contains the toner in the present invention and a bias is applied to the cleaning member in the cleaning step. . Each of the above steps is a general step per se except for the toner to be used and bias application in cleaning, and can be performed using a known image forming apparatus such as a copying machine or a facsimile machine.

  In the image forming method of the present invention, it is preferable to further include a recycling step. The cleaning step is a step of collecting excess toner when forming a toner image. The recycling process is a process of transferring the toner collected in the cleaning process to a developing device.

  The image forming method including the cleaning process and the recycling process can be performed using an image forming apparatus such as a toner recycling type copying machine or a facsimile machine. The present invention can also be applied to a recycling system in which the cleaning process is omitted and toner is collected simultaneously with development.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following description, “part” and “%” all mean “part by mass” and “mass%” unless otherwise specified.

<Various physical property measurement methods>
First, methods for measuring physical properties of toners and the like used in Examples and Comparative Examples will be described.
(Measurement method of particle size and particle size distribution)
The particle size and particle size distribution measurement in the present invention will be described. When the particle size of the particle to be measured in the present invention is 2 μm or more, a Coulter counter TA-II type (manufactured by Beckman-Coulter) is used as the measuring device, and an ISOTON-II (manufactured by Beckman-Coulter) is used as the electrolyte. did.

  As a measurement method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant. This was added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. The volume average particle diameter, GSDv, and GSDp were determined as described above. The number of particles to be measured was 50,000.

(Toner shape factor SF1 measurement method)
The toner shape factor SF1 is calculated by taking the optical microscope image of the toner spread on the slide glass into a Luzex image analyzer through a video camera and calculating the square of the maximum length of 50 toners / projection area (ML ² / A). , Obtained by calculating an average value.

(Method for measuring the molecular weight and molecular weight distribution of toner and resin particles)
In the present invention, the specific molecular weight distribution is performed under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)”, and the column uses two “TSKgel, SuperHM-H (6.0 mm ID × 15 cm, manufactured by Tosoh Corporation)” THF (tetrahydrofuran) was used as an eluent. As experimental conditions, the sample concentration was 0.5%, and the flow rate was 0.6 ml / min. The experiment was conducted using a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

(Volume average particle diameter of resin particles, colorant particles, etc.)
Volume average particle diameters of resin fine particles, colorant particles, and the like were measured with a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.).

(Measurement method of glass transition temperature)
The melting point of the release agent used in the toner of the present invention, the resin particles, and the glass transition temperature of the toner were determined from the main maximum peak measured according to ASTM D3418-8. The glass transition point was the temperature at the intersection of the extension line of the base line and the rising line in the endothermic part, and the melting point was the temperature at the apex of the endothermic peak.
For the measurement, DSC-7 manufactured by PerkinElmer was used. The temperature correction of the detection part of this apparatus was performed using the melting point of indium and zinc, and the heat quantity was corrected using the heat of fusion of indium. In addition, an aluminum pan was used as a sample cell, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

<Preparation of each dispersion>
(Resin particle dispersion)
・ Styrene 328 parts ・ n-butyl acrylate 72 parts ・ acrylic acid 8 parts ・ dodecanethiol 14 parts

What mixed and dissolved the above is 6 parts of nonionic surfactant (Nonipol 400: manufactured by Sanyo Kasei Co., Ltd.) and 10 parts of anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 550 parts of ion-exchanged water. Then, the mixture was dispersed and emulsified in a flask, slowly stirred and mixed for 10 minutes, and then 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added.
Next, after sufficiently replacing the nitrogen in the system sufficiently, the flask was stirred and heated in an oil bath until the temperature in the system reached 70 ° C. while stirring, and emulsion polymerization was continued for 7 hours. As a result, an anionic resin particle dispersion having a volume average particle size of 152 nm, a solid content of 40%, a glass transition temperature of 52 ° C., and a weight average molecular weight (hereinafter sometimes abbreviated as Mw) 3000 was obtained.

(Colorant dispersion)
・ Carbon black (Mogal L: Cabot) 60 parts ・ Nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd.) 6 parts ・ Ion exchange water 240 parts A colorant dispersion in which colorant (carbon black) particles having a volume average particle diameter of 250 nm are dispersed by stirring with an optimizer for 10 minutes. did.

(Release agent dispersion)
・ 100 parts of paraffin wax (HNP0190: manufactured by Nippon Seiwa Co., Ltd., melting point: 85 ° C.) 5 parts of cationic surfactant (Sanisol B50: manufactured by Kao Corporation) 240 parts of ion-exchanged water are mixed and heated to 95 ° C. In a round stainless steel flask, the mixture was dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with a pressure discharge homogenizer, and a release agent having a volume average particle diameter of 550 nm. A release agent dispersion in which particles were dispersed was prepared.

<Production of toner>
(Toner 1)
-Resin particle dispersion 234 parts-Colorant dispersion 30 parts-Release agent dispersion 40 parts-Aluminum sulfate (manufactured by Wako Pure Chemical Industries) 6 parts

  The above components were mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA), and then heated to 48 ° C. while stirring the flask in an oil bath for heating. After holding at 48 ° C. for 30 minutes, the volume average particle diameter was measured, and it was confirmed that aggregated particles of about 4.5 μm were formed. Further, the temperature of the heating oil bath was raised and maintained at 50 ° C. for 30 hours. When the particle size was measured, it was confirmed that aggregated particles having a volume average particle diameter of about 5.0 μm were produced. Thereafter, a 1N sodium hydroxide aqueous solution was added to the dispersion containing the aggregated particles to adjust the pH to 6.5. Thereafter, the stainless steel flask was sealed, heated to 97 ° C. while continuing stirring using a magnetic seal, and held for 4 hours. After cooling, the volume average particle diameter was measured to be 5.1 μm.

  Toner particles were filtered from the prepared toner particle-containing liquid, and washed with ion-exchanged water three times. Thereafter, 100 parts of toner particles are dispersed in 3000 parts of ion-exchanged water, and 1N sodium hydroxide is added to adjust the pH to 9.5. Then, the toner particles are transferred again into a round stainless steel flask, and the flask is stirred with a heating oil bath. The mixture was heated to 80 ° C. and held for 2 hours. Thereafter, the pH of the toner particle dispersion is adjusted to 7.0 with a 0.5N aqueous nitric acid solution, filtered, washed with ion-exchange water three times, vacuum dried for 10 hours, sieved, and sieved. Toner particles 1 having an average particle diameter of 5.2 μm, GSDv of 1.21, GSDp of 1.25, and shape factor SF1 of 130 were obtained.

-Measurement of electrical conductivity and surface tension-
The amount of residual stabilizer in the toner particles after drying was measured by electric conductivity and surface tension as follows. After dissolving 1 part of the toner particles using 10 parts of acetone, 100 parts of ion exchange water was added, and the precipitate was separated by filtration, and the electric conductivity and surface tension of the solution were measured. In the case of toner particles 1, the electric conductivity was 15 μS / cm and the surface tension was 40 mN.

  To 100 parts of the toner particles, 2 parts of hydrophobic silica (TS720: manufactured by Cabot) was added and mixed with a Henschel mixer at 30 m / s for 3 minutes (22 ° C.) to obtain toner 1.

-Measurement of dielectric loss factor-
The dielectric loss factor of the toner after silica treatment was measured as follows. Five parts of the toner were pelleted, set between electrodes [SE-71 type solid electrode, manufactured by Ando Electric Co., Ltd.], and measured with an LCR meter (4274A type, Yokogawa Hewlett Packard) at 5V. The dielectric loss factor is obtained by the following equation (1).
Dielectric loss factor = [14.39 / (W × D ² )] × G _X × T _X × 10 ¹² (1)
Here, W = 2πf (f: measurement frequency 100 kHz), D: electrode diameter (cm) G _X : conductivity (S), T _X : sample thickness (cm). As a result of the measurement, the toner 1 had a dielectric loss factor of 0.015.

(Toner 2)
A toner particle-containing liquid was prepared in the same manner as toner particle 1 in the preparation of toner 1. Toner particles were filtered from the prepared toner particle-containing liquid, and washed with ion-exchanged water three times. Thereafter, 100 parts of toner particles are dispersed in 3000 parts of ion-exchanged water, and 1N sodium hydroxide is added to adjust the pH to 9.5. Then, the toner particles are transferred again into a round stainless steel flask, and the flask is stirred with a heating oil bath. Heat to 70 ° C. and hold for 2 hours. Thereafter, the toner particles were adjusted to pH 7.0 with a 0.5N aqueous nitric acid solution, filtered, washed with ion-exchanged water three times, vacuum-dried for 10 hours, and sieved to obtain a volume average particle size. Toner particles 2 having a size of 5.2 μm, a GSDv of 1.23, a GSDp of 1.26, and a shape factor SF1 of 130 were obtained.

The toner particles 2 were measured for electric conductivity and surface tension in the same manner as the toner particles 1. As a result, the electric conductivity was 20 μS / cm, and the surface tension was 40 mN.
Further, in the same manner as in the toner particles 1, hydrophobic silica was attached to the outside to obtain a toner 2. As a result of measuring the dielectric loss factor of the toner 2 in the same manner as the toner 1, the dielectric loss factor of the toner 2 was 0.017.

(Toner 3)
-Resin particle dispersion 234 parts-Colorant dispersion 30 parts-Release agent dispersion 40 parts-Aluminum sulfate (manufactured by Wako Pure Chemical Industries) 6 parts

  The above components were mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA), and then heated to 42 ° C. while stirring the flask in a heating oil bath. After holding at 42 ° C. for 20 minutes, the volume average particle diameter was measured, and it was confirmed that aggregated particles of about 4.0 μm were formed. Here, after adding 50 parts of the resin particle dispersion, the temperature of the heating oil bath was further raised and maintained at 50 ° C. for 1 hour. When the volume average particle diameter was measured, it was confirmed that aggregated particles of about 4.6 μm were formed. Then, after adding 3 parts of an anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku) to the dispersion containing the aggregated particles, the stainless steel flask was sealed, and stirring was continued using a magnetic seal. Heated to ° C and held for 4 hours. After cooling, the volume average particle diameter was measured with a Coulter counter to be 4.3 μm.

  The toner particles were separated by filtration and washed three times with ion exchange water. Further, it was dispersed in ion-exchanged water, adjusted to pH 10.0 with 1N sodium hydroxide, and kept at 80 ° C. for 2 hours in a round stainless steel flask. Thereafter, the toner was washed three times with ion-exchanged water and vacuum-dried for 10 hours to obtain a toner having a volume average particle size of 5.2 μm and a shape factor SF1 of 129. Next, sieving was performed to obtain toner particles 3 having a volume average particle size of 4.4 μm, GSDv of 1.19, GSDp of 1.22, and shape factor SF1 of 115.

The toner particles 3 were measured for electrical conductivity and surface tension in the same manner as the toner particles 1. As a result, the electric conductivity was 17 μS / cm and the surface tension was 48 mN.
Further, the toner 3 was obtained by attaching hydrophobic silica to the outside in the same manner as the toner particles 1. As a result of measuring the dielectric loss factor of the toner 3 in the same manner as the toner 1, the dielectric loss factor of the toner 3 was 0.020.

(Toner 4)
・ Resin particle dispersion 234 parts ・ Colorant dispersion 30 parts ・ Releasing agent dispersion 40 parts ・ Polyaluminum hydroxide (Pho2S, manufactured by Asada Chemical Co., Ltd.) 0.5 part

  The above components were mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA), and then heated to 55 ° C. while stirring the flask in a heating oil bath. After holding at 55 ° C. for 30 minutes, the volume average particle diameter was measured, and it was confirmed that 4.5 μm aggregated particles were formed. Further, the temperature of the heating oil bath was raised and held at 65 ° C. for 1 hour. When the volume average particle diameter was measured, it was confirmed that 5.3 μm aggregated particles were formed. Then, after adding 3 parts of an anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku) to the dispersion containing the aggregated particles, the stainless steel flask was sealed, and stirring was continued using a magnetic seal. Heat to 0 ° C. and hold for 4 hours. When the volume average particle size was measured after cooling, it was confirmed to be 5.4 μm.

  Toner particles were filtered off from the prepared toner particle-containing liquid, washed with a sodium hydroxide solution having a pH of 10.0, and then washed with ion-exchanged water three times. Thereafter, the toner particles are freeze-dried for 6 hours and then vacuum-dried for 24 hours and sieved to a toner having a volume average particle size of 5.4 μm, a GSDv of 1.23, a GSDp of 1.27, and a shape factor SF1 of 130. Particles 4 were obtained.

The toner particles 4 were measured for electric conductivity and surface tension in the same manner as the toner particles 1. As a result, the electric conductivity was 16 μS / cm, and the surface tension was 50 mN.
Further, the toner 4 was obtained by attaching hydrophobic silica to the outside in the same manner as the toner particles 1. As a result of measuring the dielectric loss factor of the toner 4 in the same manner as the toner 1, the dielectric loss factor of the toner 4 was 0.022.

(Toner 5)
-Resin particle dispersion 234 parts-Colorant dispersion 30 parts-Release agent dispersion 20 parts-Cationic surfactant (Sanisol C, manufactured by Kao Corporation) 1.5 parts

  The above components were mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA), and then heated to 42 ° C. while stirring the flask in an oil bath for heating. After holding at 42 ° C. for 30 minutes, the volume average particle diameter was measured, and it was confirmed that 4.0 μm aggregated particles were formed. Here, after additionally adding 50 parts of the same resin particle dispersion as described above, the temperature of the heating oil bath was further raised and maintained at 64 ° C. for 1 hour. When the volume average particle diameter was measured, it was confirmed that 5.3 μm aggregated particles were generated. Then, after adding 3 parts of an anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku) to the dispersion containing the aggregated particles, the stainless steel flask is sealed, and stirring is continued using a magnetic seal. Heat to 97 ° C. and hold for 4 hours. After cooling, the volume average particle diameter was measured with a Coulter counter and confirmed to be 5.5 μm.

  The toner particles were separated by filtration, washed with a sodium hydroxide solution having a pH of 10.0, and then washed with ion exchange water three times. After lyophilizing for 6 hours, vacuum drying is performed for 24 hours, followed by sieving, and toner particles 5 having a volume average particle size of 5.6 μm, GSDv of 1.21, GSDp of 1.25, and shape factor SF1 of 114 Got.

For the toner particles 5, the electrical conductivity and the surface tension were measured in the same manner as the toner particles 1. As a result, the electric conductivity was 30 μS / cm, and the surface tension was 35 mN.
Further, in the same manner as the toner particles 1, hydrophobic silica was externally attached to obtain a toner 5. As a result of measuring the dielectric loss factor of the toner 5 in the same manner as the toner 1, the dielectric loss factor of the toner 5 was 0.030.

(Toner 6)
A toner particle-containing liquid was prepared in the same manner as toner particle 1 in the preparation of toner 1. Toner particles were filtered from the prepared toner particle-containing liquid, and washed with ion-exchanged water three times. Thereafter, vacuum drying was carried out for 10 hours, and sieving to obtain toner particles 6 having a volume average particle size of 5.2 μm, GSDv of 1.22, GSDp of 1.25, and shape factor SF1 of 130.

The toner particles 6 were measured for electric conductivity and surface tension in the same manner as the toner particles 1. As a result, the electric conductivity was 115 μS / cm, and the surface tension was 18 mN.
Further, the toner 6 was obtained by attaching hydrophobic silica to the outside in the same manner as the toner particles 1. As a result of measuring the dielectric loss factor of the toner 6 in the same manner as the toner 1, the dielectric loss factor of the toner 6 was 0.12.

(Toner 7)
Ingredients similar to those for obtaining toner particles 4 in the preparation of toner 4 are mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA), and then the flask is stirred with a heating oil bath. While heating to 52 ° C. After maintaining at 45 ° C. for 30 minutes, the volume average particle size of the particles was measured with a Coulter counter, and it was confirmed that aggregated particles of about 4.2 μm were formed. Here, after adding 50 parts of the resin particle dispersion, the temperature of the heating oil bath was further raised and maintained at 80 ° C. for 1 hour. When the volume average particle diameter was measured, it was confirmed that aggregated particles of about 5.4 μm were formed. Then, after adding 3 parts of an anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) to the dispersion containing the aggregated particles, the stainless steel flask is sealed and stirring is continued using a magnetic seal. The mixture was heated to 97 ° C. and held for 4 hours. After cooling, the volume average particle size was measured with a Coulter counter and confirmed to be 5.6 μm.

  The toner particles were filtered off, washed with a sodium hydroxide solution having a pH of 10.0, and then washed three times with ion-exchanged water. After freeze-drying for 6 hours, vacuum drying was performed for 24 hours. Thereafter, sieving was performed to obtain toner particles 7 having a volume average particle size of 5.6 μm, GSDv of 1.21, GSDp of 1.26, and shape factor SF1 of 130.

The toner particles 7 were measured for electric conductivity and surface tension in the same manner as the toner particles 1. As a result, the electric conductivity was 103 μS / cm, and the surface tension was 19 mN.
Further, in the same manner as the toner particles 7, hydrophobic silica was externally attached to obtain a toner 7. As a result of measuring the dielectric loss factor of the toner 7 in the same manner as the toner 1, the dielectric loss factor of the toner 7 was 0.092.

<Manufacture of carriers>
17 parts of toluene, 3 parts of a styrene-methyl methacrylate copolymer (component ratio: 40/60), and 0.2 part of carbon black (R330: manufactured by Cabot) were mixed and stirred with a stirrer for 10 minutes. A solution for forming a coating layer in which was dispersed was prepared. Next, this coating solution and 100 parts of ferrite particles (volume average particle size: 45 μm) are put into a vacuum degassing type kneader and stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. The carrier was prepared by drying.

<Manufacture of developer>
For toners 1-7, 92 parts of carrier were mixed with 8 parts of the toner by a V-type blender to obtain developers 1-7. The mixing conditions were 60 rpm and 20 minutes.

<Examples 1-3, Comparative Examples 1-4>
The developers 1 to 7 obtained as described above were evaluated for transferability and cleaning performance using a color composite machine DocuCenter Color 500 manufactured by Fuji Xerox Co., Ltd. Specifically, developers 1 to 7 are loaded with each developer of DocuCenter Color 500 as shown in each example and comparative example of Table 1, and the cleaning unit is configured as shown in FIG. 2 (applied bias: 500V), and cleaning performance was evaluated.

As evaluation conditions, it was carried out in a high-temperature and high-humidity (30 ° C., 85% RH) environment, which is a stress condition for transferability and cleanability. In addition, a type without a bias applying unit was also prepared as a cleaning unit, and a comparative verification with a type having a bias applying unit in the present invention was performed.
As an evaluation method, first, the transfer efficiency and the charge amount distribution after transfer were evaluated as initial characteristics, and then a running test of 50,000 sheets was performed, and the cleaning maintainability was compared and evaluated with / without bias.

The evaluation of the cleaning maintainability was evaluated based on the presence or absence of image defects (black stripes, black stripes) caused by poor cleaning, and the following criteria were used.
○: No image defect due to poor cleaning ×: Image defect due to poor cleaning

The transfer efficiency was determined from the following formula (3).
Transfer efficiency (%) = [(transferred toner mass (g)) / (transfer toner mass (g))] × 100 Formula (3)

The charge amount distribution was measured using a CSG (charge spectrograph) measuring device. A CSG measuring device is a device that causes a toner to be measured to move at a constant speed and in a certain direction by an air flow and applies an electric field of 100 V in a direction perpendicular to the air flow to obtain a charge distribution from the amount of toner displacement. is there. The charge amount distribution was measured by blowing the toner on the photoconductor before and after the transfer with air, measuring the toner, and judging based on the following criteria.
○: Almost no change from before transfer (reverse polarity toner amount is less than 0.1%)
Δ: Slightly reverse polarity toner is generated (Reverse polarity toner amount is 0.1 or more and less than 1%)
×: Many reverse polarity toners are generated (the reverse polarity toner amount is 1% or more)

An example of CSG measurement is shown in FIGS. 11 and 12, the horizontal axis represents the position from the center, and the vertical axis represents the number of toners. (A) shows the toner charge amount distribution on the photoconductor before transfer, and (b) shows the toner charge amount distribution on the photoconductor after transfer. FIG. 11 shows a case where the charge amount distribution hardly changes before and after transfer, and FIG. 12 shows a case where a large amount of reverse polarity toner occurs before and after transfer.
The above results are summarized in Table 1.

  As shown in Table 1, in the case where the dielectric loss factor of the toner is as low as 0.02 or less, the transfer efficiency is uniformly high as 95% or more, whereas in the case where the dielectric loss factor exceeds 0.02, it is 90%. Only high transfer efficiency could not be obtained. Correspondingly, the charge amount distribution after transfer hardly changed in the case where the dielectric loss factor was as low as 0.02 or less, whereas in the case where the dielectric loss factor was higher than 0.02, the reverse polarity was obtained. It was confirmed that a lot of toner was generated.

  In addition, the cleaning maintainability was good for the small-diameter toner and the spherical toner (Example 3) when the dielectric loss factor of the toner was 0.02 or less, whereas the dielectric loss factor was 0.02. In the case of exceeding, it was verified that a large amount of reverse polarity toner was generated after the transfer, so that the effect of the bias was not sufficiently exhibited and a cleaning failure occurred. It was also confirmed that even when the dielectric loss factor was as low as 0.02 or less, the cleaning maintainability could not be obtained if no bias was applied.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. It is the schematic which shows the structural example of the cleaning apparatus (cleaning means) in this invention. It is the schematic which shows the other structural example of the cleaning apparatus (cleaning means) in this invention. It is the schematic which shows the other structural example of the cleaning apparatus (cleaning means) in this invention. It is the schematic which shows the structural example of the cleaning apparatus (cleaning means) in this invention. It is the schematic which shows the other structural example of the cleaning apparatus (cleaning means) in this invention. It is the schematic which shows the other structural example of the cleaning apparatus (cleaning means) in this invention. It is a graph which shows the relationship between the electrical conductivity of a toner particle extract, and a charging characteristic. 6 is a graph showing the relationship between the surface tension of toner particle extraction liquid and charging characteristics. 6 is a graph showing a relationship between a dielectric loss rate of toner and transfer efficiency. FIG. 6 is a diagram illustrating an example of a change in toner charge amount distribution before and after transfer. FIG. 6 is a diagram illustrating another example of a change in toner charge amount distribution before and after transfer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 2 Charger 3 Image writing apparatus 4 Developing unit 5 Primary transfer roll 6 Cleaning device (cleaning means)
7 Fixing device (fixing means)
8 Recording paper 12 Intermediate transfer member 16 Backup roll 17 Secondary transfer roll 18 Toner removing device 20, 41 Cleaning blade 24, 46 Cleaner housing 25, 47 Seal member 26, 32, 48, 49 Bias applying means 27, 44 Brush 28, 36, 40, 45 Auger 33 Magnetic brush 35 Mag roll

Claims (2)

At least a toner image forming unit that forms a toner image on the image carrier, a transfer unit that transfers the toner image to a transfer target, a fixing unit that fixes the transferred toner image to a recording medium, and an image carrier In the image forming apparatus provided with a cleaning means for cleaning the transfer residual toner of
An image forming apparatus, wherein a toner having a dielectric loss ratio of 0.001 to 0.02 is used as the toner, and a bias is applied to a cleaning member in the cleaning unit. At least a toner image forming step of forming a toner image on the image carrier, a transfer step of transferring the toner image to a transfer target, a fixing step of fixing the transferred toner image on a recording medium, and an image carrier And an image forming method including a cleaning step of cleaning the transfer residual toner.
An image forming method, wherein a dielectric loss ratio of the toner is in a range of 0.001 to 0.02, and a bias is applied to a cleaning member in the cleaning step.

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