JP2010224579A - Image forming apparatus and process cartridge used in the image forming apparatus - Google Patents

Abstract

An image forming apparatus, a process cartridge, and a toner capable of preventing a decrease in toner tribo in a developing process using a contact developing method, maintaining good density gradation characteristics, and stably forming an image.
A surface layer of an image carrier that carries an electrostatic latent image of an image forming apparatus that forms an image by a contact development method using a negatively charged toner having toner base particles and at least one external additive. The relationship between the triboelectric charge train of the toner base particles and the external additive was set in the order from the negative side to the external additive, the toner base particles, and the surface layer of the image carrier.
[Selection] Figure 1

Description

  The present invention relates to image formation using an electrophotographic recording system, comprising an exposure device that emits light modulated according to an image signal, and a contact development device for developing an electrostatic latent image formed by the exposure device. Relates to the device. In particular, the present invention relates to an image forming apparatus that prevents inconsistencies in density gradation expression and image scattering due to insufficient toner charge amount due to reversely charged toner. The present invention also relates to a process cartridge and toner used in the apparatus.

  In general, an image forming apparatus using an electrophotographic recording method corresponds to an image signal by exposing a surface of the photoconductor to be rotated, a charger that uniformly charges the surface of the photoconductor, and the surface of the photoconductor. An exposure means for forming the electrostatic latent image, a development means for developing the electrostatic latent image with toner to form a visible image, a transfer means for transferring the visible image onto the recording paper, and the recording paper Fixing means for fixing the visible image transferred to the recording medium.

  In this case, as developing means, a developing roller contacts the photosensitive member for development (hereinafter referred to as a contact developing method), and a developing roller performs the development without contact with the photosensitive member (hereinafter referred to as “contact developing method”). These are known as non-contact development methods). As the contact developing method, as disclosed in Japanese Patent Application Laid-Open Nos. 62-223771 and 1-295966, a type in which the developing roller is elastically brought into contact with the surface of the photoreceptor, Japanese Patent Application Laid-Open No. 4-247478 is disclosed. As a developing roller, there is a type in which a thin resin sleeve is provided on the surface of a roller made of an elastic material.

  FIG. 3 is a schematic cross-sectional view showing a main configuration of an example of an known image forming apparatus (hereinafter referred to as a conventional example) using a contact developing system as a developing unit.

  In FIG. 3, 101 is a drum-shaped photoconductor, 102 is a contact developing roller, 103 is a developing unit, 104 is a transfer roller, 105 is a charging roller, 106 is an exposure means, 108 is a toner supply roller, 109 is a developing blade, and 110 is Toner.

The photosensitive drum 101 has a configuration in which a photosensitive material is applied to the surface of a drum-shaped metal element tube or the like, and is driven to rotate in the direction of an arrow about a rotation axis by a driving device (not shown) during operation. The developing roller 102 and the developing unit 103 constitute a developing unit, and the developing roller 2 is configured to be always in contact with the surface of the photoreceptor 1 and to rotate as the photosensitive drum 1 rotates. The developing unit 103 includes a developing blade 109 configured to contact the developing roller 102. A thin layer of toner 110 is formed on the developing roller 102 by passing the toner 110 between the developing blade 109 and the developing roller 102 to regulate the amount of the toner 110 on the developing roller 102. In addition, a sufficient triboelectric charge (tribo) is imparted to the toner 110 by friction at the contact portion. Further, the developing unit 103 is provided with a toner supply roller 108 that contacts the developing roller 102 at a position upstream of the developing blade 109 in the rotation direction of the developing roller 102, and supplies and carries the toner 110 to the developing roller 102. I am letting. The transfer roller 104 constitutes a transfer means, and is configured to rotate in contact with the photosensitive drum 101 so that a recording sheet (not shown) passes between the photosensitive drum 101 and the transfer roller 104 during transfer. . The charging roller 105 uniformly charges the surface of the photosensitive drum 101 with a constant potential by a charging voltage generating power source (not shown), and is pressed against the surface of the photosensitive drum 101 with a predetermined pressing force. The photosensitive drum 101 is charged while being rotated following the rotation of 101. The exposure means 106 supplies an optical signal modulated by an image signal from an image signal source (not shown), applies the optical signal to the surface of the uniformly charged photosensitive drum 101, and corresponds to the image signal. An electrostatic latent image is formed.

  The operation of the conventional example will be described below. The overall operation of the conventional example will be described. First, the surface of the photosensitive drum 101 rotating in the direction of the arrow a shown in the drawing is uniformly charged by the charging roller 105, and then the image signal is applied to the surface by the exposure means 106. A corresponding electrostatic latent image is formed. Subsequently, a developing roller 102 to which a developing voltage is applied from a developing voltage generating power source (not shown) applies toner 110 to the electrostatic latent image and develops it, and the surface of the photosensitive drum 101 corresponds to the electrostatic latent image. A visible image is formed. The visible image formed on the surface of the photosensitive drum 101 is transferred onto a recording sheet by a transfer roller 104, and the transferred visible image is fixed on the recording sheet and then taken out together with the recording sheet as a recorded image. . On the other hand, the surface portion of the photosensitive drum 101 that has passed through the transfer roller 104 is subjected to toner cleaning via a toner cleaner means (not shown), and the above-described steps are repeated again.

  The structure of the photosensitive layer of the photosensitive drum 101 includes a single layer type in which both the charge generation material and the charge transport material are contained in the same layer, a charge generation layer containing the charge generation material, and a charge transport layer containing the charge transport material. It is divided roughly into the laminated type which has. As an electrophotographic photosensitive member having a laminated type photosensitive layer, there is one in which a charge generation layer and a charge transport layer are laminated in this order on a substrate, and the charge transport layer is composed of biphenylene, anthracene, pyrene and the main chain or side chain. A polycyclic aromatic compound having a structure such as phenanthrene; a nitrogen-containing ring compound such as indole, carbazole, oxadiazole and pyrazoline; a solution in which a charge transporting material such as a hydrazone compound and a styryl compound is dissolved in a film-forming resin It is formed by applying and drying. Examples of the resin having a film forming property include polyester, polycarbonate, polystyrene, polymethacrylic acid ester, and polyarylate. The charge generation layer is composed of an azo pigment such as Sudan Red and Diane Blue; a quinone pigment such as pyrene, quinone and anthanthrone; a quinocyanine pigment; a perylene pigment; an indigo pigment such as indigo and thioindigo; It is formed by applying a dispersion liquid dispersed in a resin such as butyral, polystyrene, polyvinyl acetate and acrylic resin on a support and drying, or vacuum-depositing the pigment on the support. On the other hand, the single-layer type photosensitive layer is formed by applying a solution obtained by dispersing and dissolving the charge generating substance and the charge transporting substance in the resin to a support and drying it.

  In addition, as a method of expressing density gradation in an electrophotographic image forming apparatus, a gradation expression method (in this way, a light source is irradiated with light from a light source and the latent image potential on a photosensitive drum is varied in accordance with the amount of reflected light. The electrostatic latent image formed in this way is hereinafter referred to as an analog latent image) and a gradation expression method (this is a method for irradiating a photosensitive drum with light modulated in accordance with an image signal from an exposure device and changing the irradiation area. The electrostatic latent image formed in this manner is hereinafter referred to as a digital latent image). However, when these latent images are developed using a contact development method, density gradation characteristics are obtained by toner tribo. May deviate significantly.

FIG. 4 shows density gradation characteristics for an analog latent image when toner tribos (toner triboelectric charge amounts) are different. In the figure, the curve indicated by the black plot indicates that the toner tribo is appropriate, and the curve indicated by the white plot indicates that the toner tribo has decreased. As shown in FIG. 4, when the toner tribo is lowered, the density suddenly rises from the low contrast potential, and the density is saturated even if the contrast potential is raised thereafter. On the other hand, if the tribo is appropriate, density gradation characteristics corresponding to the contrast potential can be obtained. This is a phenomenon caused by the difference in the mirror force applied to the developing roller due to the difference in toner tribo. Since the toner force applied to the developing roller is weak when the toner tribo is lowered, it follows the force received from the electric field between the photosensitive drum and the developing roller. It is considered that the toner easily transfers to the photosensitive drum even at a low contrast potential. The toner tribo fluctuates depending on the usage time and the number of times of use, and it can be said that the density gradation characteristic in the contact development method is disadvantageous for the analog latent image.

  Next, FIG. 5 shows density gradation characteristics for digital latent images when toner tribos are different. In the figure, the curve indicated by the black plot indicates that the toner tribo is appropriate, the curve indicated by the white plot indicates that the toner tribo has decreased, and the solid line indicates ideal density gradation characteristics. As shown in FIG. 5, compared to the density gradation characteristic of the analog latent image, even when the toner tribo is lowered, a generally good density gradation characteristic is obtained, and the digital latent image is suitable for the contact development method. Recognize. This is because the difference in density gradation characteristics of the digital latent image is the difference in the density of the electrostatic latent image, which has a high contrast potential in FIG. Therefore, it is considered that the density gradation characteristic due to the difference in toner tribo in the digital latent image is smaller than that in the analog latent image.

  However, as shown in FIG. 5, when the toner tribo is low, the density gradation characteristic shifts at a density higher than the ideal density gradation characteristic even in a light gradation, so that in image formation such as a photographic image. Becomes too dark overall, resulting in a dark and dull image. The same applies to the case where a line image typified by characters or the like is formed. When the toner tribo is low, excessive toner is transferred to the line image latent image, increasing the height of the toner image on the photosensitive drum, and The amount of consumption increases, and the line drawing causes a decrease in image quality such as toner scattering.

  Therefore, in the contact development method, in order to maintain good density gradation characteristics and prevent an increase in toner consumption, it is necessary to suppress a decrease in toner tribo.

  However, in the contact developing method, the toner blade is regulated to a predetermined toner layer thickness and a predetermined tribo is imparted to the toner, but the surface of the image carrier (photosensitive drum) that carries the electrostatic latent image When the toner rubs, if the relationship of the triboelectric charge train on the surface of the photosensitive drum with respect to the toner is the same polarity as the toner, the toner tribo will fall below a predetermined value or a toner charged to the opposite polarity will be generated. . As the number of times the developing device is used, the number of times of rubbing with the photosensitive drum increases, the reduction in the toner tribo is promoted. This causes problems such as scattering and an increase in toner consumption. Furthermore, the toner charged to the opposite polarity becomes a reverse fog that adheres to the non-image portion on the photosensitive drum, which causes a further problem that the toner consumption further increases.

  The present invention has been made in view of the above-described problems, and prevents the toner tribo from being lowered in the contact development method, and irradiates the photosensitive drum with light modulated in accordance with the image signal from the exposure device, thereby changing the irradiation area. It is an object of the present invention to provide an image forming apparatus, a process cartridge, and a toner capable of maintaining good density gradation characteristics and performing stable image formation in the developing process of the electrostatic latent image. Another object is to provide an image forming apparatus, a process cartridge, and toner that prevent excessive toner consumption.

  Another object of the present invention is to provide an image forming apparatus, a process cartridge, and a toner that are free from reversal fog even when used for a long period of time.

In order to solve the above problems, the present inventors have conducted intensive studies.
The present invention has been completed by finding that there is a great correlation in the relationship between the toner base particles, the external additive, and the triboelectric charge train with the surface layer of the photosensitive drum.

  That is, the present invention is as follows.

(1) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more types At least a toner carrier for carrying a negatively charged toner having an external additive and transporting it to the image carrier, and forming a development region by contacting the toner carrier to the image carrier An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image to form a toner image by electrically attaching the toner to the electrostatic latent image on the image bearing member in the developing region; The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the order from the negative side to the external additive, toner base particles, and the surface layer of the image carrier. Image forming apparatus.

(2) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more types At least a toner carrier for carrying a negatively charged toner having an external additive and transporting it to the image carrier, and forming a development region by contacting the toner carrier to the image carrier An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image to form a toner image by electrically attaching the toner to the electrostatic latent image on the image bearing member in the developing region; Further, the relationship between the surface layer of the image carrier, the toner base particles and the triboelectric charge train of the external additive is the order from the minus side to the toner base particles, the external additive, and the surface layer of the image carrier. Image forming apparatus.

(3) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more types At least a toner carrier for carrying a negatively charged toner having an external additive and transporting it to the image carrier, and forming a development region by contacting the toner carrier to the image carrier An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image to form a toner image by electrically attaching the toner to the electrostatic latent image on the image bearing member in the developing region; The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the order from the negative side to the toner base particles, the surface layer of the image carrier, and the external additive. Image forming apparatus.

(4) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more types At least a toner carrier for carrying a positively charged polarity toner having an external additive and transporting the toner to the image carrier, and a developing region is formed by bringing the toner carrier into contact with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image to form a toner image by electrically attaching the toner to the electrostatic latent image on the image bearing member in the developing region; The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the order from the positive side to the external additive, toner base particles, and the surface layer of the image carrier. Image forming apparatus.

(5) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more types At least a toner carrier for carrying a positively charged polarity toner having an external additive and transporting the toner to the image carrier, and a developing region is formed by bringing the toner carrier into contact with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image to form a toner image by electrically attaching the toner to the electrostatic latent image on the image bearing member in the developing region; Further, the relationship between the surface layer of the image carrier, the toner base particles and the triboelectric charge train of the external additive is the order from the plus side to the toner base particles, the external additive, and the surface layer of the image carrier. Image forming apparatus.

(6) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more types At least a toner carrier for carrying a positively charged polarity toner having an external additive and transporting the toner to the image carrier, and a developing region is formed by bringing the toner carrier into contact with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image to form a toner image by electrically attaching the toner to the electrostatic latent image on the image bearing member in the developing region; Further, the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the order from the plus side to the toner base particles, the surface layer of the image carrier, and the external additive. Image forming apparatus.

(7) The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives At least a toner carrying member for carrying a negatively charged toner having a negative charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. A developing device for visualizing the electrostatic latent image to form a toner image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region; and (a) charging the image carrier. Charging hand to do (B) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and (c) a transfer in which the toner image formed by the developing device is transferred to a transfer material. And (d) a cleaning unit that removes toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. 0 or 1 or more means, and the relationship between the surface layer of the image carrier, the toner base particles and the external additive is such that the relationship between the external additive, the toner base particles and the surface layer of the image carrier is from the minus side. Process cartridge characterized by being in order.

(8) The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives At least a toner carrying member for carrying a negatively charged toner having a negative charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. A developing device for visualizing the electrostatic latent image to form a toner image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region; and (a) charging the image carrier. Charging hand to do (B) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and (c) a transfer in which the toner image formed by the developing device is transferred to a transfer material. And (d) a cleaning unit that removes toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. 0 or 1 or more means, and the relationship between the surface layer of the image carrier, the toner mother particles and the external additive is such that the relationship between the toner mother particles, the external additive and the surface of the image carrier is from the minus side. Process cartridge characterized by being in order.

(9) The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives At least a toner carrying member for carrying a negatively charged toner having a negative charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. A developing device for visualizing the electrostatic latent image to form a toner image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region; and (a) charging the image carrier. Charging hand to do (B) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and (c) a transfer in which the toner image formed by the developing device is transferred to a transfer material. And (d) a cleaning unit that removes toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. 0 or 1 or more means, and the relationship between the surface layer of the image carrier, the toner mother particles and the external additive is such that the relationship between the toner mother particles, the surface layer of the image carrier and the external additive is from the minus side. Process cartridge characterized by being in order.

(10) The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives At least a toner carrier for carrying a positively charged toner having a positive charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. A developing device for visualizing the electrostatic latent image to form a toner image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region; and (a) charging the image carrier. Charging hand to do (B) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and (c) a transfer in which the toner image formed by the developing device is transferred to a transfer material. And (d) a cleaning unit that removes toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. 0 or 1 or more means, and the relationship between the surface layer of the image carrier, the toner base particles and the external additive is such that the relationship between the external additive, the toner base particles, and the surface layer of the image carrier is from the plus side. Process cartridge characterized by being in order.

(11) The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives At least a toner carrier for carrying a positively charged toner having a positive charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. A developing device for visualizing the electrostatic latent image to form a toner image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region; and (a) charging the image carrier. Charging hand to do (B) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and (c) a transfer in which the toner image formed by the developing device is transferred to a transfer material. And (d) a cleaning unit that removes toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. 0 or 1 or more means, and the relationship between the surface layer of the image carrier, the toner base particles and the external additive is such that the relationship between the toner base particles, the external additive, and the surface layer of the image carrier is from the plus side. Process cartridge characterized by being in order.

(12) The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives At least a toner carrier for carrying a positively charged toner having a positive charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. A developing device for visualizing the electrostatic latent image to form a toner image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region; and (a) charging the image carrier. Charging hand to do (B) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and (c) a transfer in which the toner image formed by the developing device is transferred to a transfer material. And (d) a cleaning unit that removes toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. 0 or 1 or more means, and the relationship between the surface layer of the image carrier, the toner base particles and the external charge additive is such that the relationship between the toner base particles, the surface layer of the image carrier and the external additive is from the plus side. Process cartridge characterized by being in order.

(13) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner carrying the image carrier. At least a toner carrier for transporting the toner to the image forming body, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and in the developing region, the toner is electrostatically latent on the image carrier. A toner used in an image forming apparatus including a developing device that visualizes the electrostatic latent image by being electrically attached to an image to form a toner image. The toner includes toner base particles and one type of toner. A negatively chargeable toner having the above external additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive from the negative side, the external additive, the toner base particles, and the image It is characterized by the order of the surface layer of the carrier Toner.

(14) An image carrier that carries an electrostatic latent image; an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; and a toner carrying the image carrier. At least a toner carrier for transporting the toner to the image forming body, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and in the developing region, the toner is electrostatically latent on the image carrier. A toner used in an image forming apparatus including a developing device that visualizes the electrostatic latent image by being electrically attached to an image to form a toner image. The toner includes toner base particles and one type of toner. A negatively chargeable toner having the above external additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the toner base particles, the external additive, and the image from the negative side. It is characterized by the order of the surface layer of the carrier Toner.

(15) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner carrying the image carrier. At least a toner carrier for transporting the toner to the image forming body, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and in the developing region, the toner is electrostatically latent on the image carrier. A toner used in an image forming apparatus including a developing device that visualizes the electrostatic latent image by being electrically attached to an image to form a toner image. The toner includes toner base particles and one type of toner. A negatively chargeable toner having the above external additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the toner base particles and the surface layer of the image carrier from the negative side. , Characterized by the order of external additives Toner.

(16) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner carrying the image carrier. At least a toner carrier for transporting the toner to the image forming body, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and in the developing region, the toner is electrostatically latent on the image carrier. A toner used in an image forming apparatus including a developing device that visualizes the electrostatic latent image by being electrically attached to an image to form a toner image. The toner includes toner base particles and one type of toner. A positively chargeable toner having the above external additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is from the positive side, the external additive, toner base particles, image The toner is characterized by the order of the surface layer of the carrier. Over.

(17) An image carrier that carries an electrostatic latent image; an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; and a toner carrying the image carrier. At least a toner carrier for transporting the toner to the image forming body, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and in the developing region, the toner is electrostatically latent on the image carrier. A toner used in an image forming apparatus including a developing device that visualizes the electrostatic latent image by being electrically attached to an image to form a toner image. The toner includes toner base particles and one type of toner. A positively chargeable toner having the above external additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive has a relationship from the positive side to the toner base particles, external additives, and image. The toner is characterized by the order of the surface layer of the carrier. Over.

(18) An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner carrying the image carrier. At least a toner carrier for transporting the toner to the image forming body, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and in the developing region, the toner is electrostatically latent on the image carrier. A toner used in an image forming apparatus including a developing device that visualizes the electrostatic latent image by being electrically attached to an image to form a toner image. The toner includes toner base particles and one type of toner. A positively chargeable toner having the above external additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is the toner base particles and the surface layer of the image carrier from the positive side. , Characterized by the order of external additives Over.

  As described above, according to the present invention, the surface layer of the image carrier and the negative charge characteristic toner are formed when an image is formed by the contact development method in which the toner carrier is brought into contact with the image carrier at a predetermined pressure. (A) external additive, toner base particles, surface layer of photosensitive drum 1, (b) toner base particles, external additive, photosensitive drum 1 (C) the toner mother particles, the surface layer of the photosensitive drum 1, and the external additive in this order, so that the toner is maintained at a normal charging polarity even when the surface of the photosensitive drum and the toner are rubbed, and It is possible to prevent the toner tribo from being lowered. In addition, the density gradation characteristics in the developing process of the electrostatic latent image obtained by irradiating the image carrier with the irradiation area varied from the exposure device by the light modulated in accordance with the image signal is satisfactorily maintained; It is possible to provide an image forming apparatus, a process cartridge, and toner that can stably form an image. Further, it is possible to form an image without scattering and to prevent excessive toner consumption. Further, it is possible to prevent the reverse fogging even in the long-term continuous use of the image forming apparatus.

1 is a schematic configuration diagram showing a first embodiment of an image forming apparatus of the present invention. 1 is a schematic configuration diagram showing a state in which a process cartridge is loaded in an image forming apparatus of the present invention. Schematic configuration diagram showing an example of a conventional image forming apparatus Graph showing density gradation characteristics for analog latent image Graph showing density gradation characteristics for digital latent images Schematic diagram of triboelectric charge measuring device Diagram for explaining image density measurement Diagram for explaining image density measurement Diagram for explaining image density measurement The figure for demonstrating the evaluation method of the scattering of the toner in an Example

  Embodiments of the present invention will be described below.

<Toner> First, the toner used in the present invention will be described. The toner used in the present invention is a negatively charged or positively charged toner having toner base particles and one or more external additives. In the present invention, a negatively charged toner (hereinafter sometimes referred to as “negatively chargeable toner”) is a toner that is negatively charged when rubbed against a developing blade or a developing roller. Located in. On the other hand, a positively charged toner (hereinafter, “positively charged toner”) is a toner that is positively charged when rubbed against a developing blade or a developing roller, and is positioned on the positive side in the frictional charge train. In the present invention, the triboelectric chargeability of the toner is determined by the combination of the binder resin, the colorant, the charge control agent and the external additive contained in the toner base particles constituting the toner, the content of each material, and the like. .

  In order to achieve the above object, in the relationship between the toner and the surface layer of the image carrier, the charge polarity of the surface layer of the image carrier is different from that of the toner in the developing device. And more preferable.

  As the binder resin used for the toner base particles in the present invention, conventionally known resins can be used, and are not particularly limited, but polystyrene, poly-α-methylstyrene, styrene-propylene copolymer, styrene-butadiene are used. Copolymer, Styrene-vinyl chloride copolymer, Styrene-vinyl acetate copolymer, Styrene-acrylic acid ester copolymer, Styrene-methacrylic acid acrylic copolymer, Vinyl chloride resin, Polyester resin, Epoxy resin, Phenol resin Polyurethane resins and the like can be used alone or in combination. Of these, styrene-acrylic acid ester copolymers, styrene-methacrylic acid acrylic copolymers, and polyester resins are preferred.

  In addition, as the colorant used for the toner base particles in the present invention, a known colorant can be used, for example, carbon black; I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209; I. Pigment Violet 19: C.I. I. Vat Red 1, 2, 10, 13, 15, 23, 29, 35; I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; I. Disper thread 9; I. Solvent violet 8, 13, 14, 21, 27; C.I. I. Oil-soluble dyes such as disperse violet 1, C.I. I. B. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; I. Basic dyes such as basic violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28; I. Pigment blue 2, 3, 15, 16, 17; I. Bat Blue 6; C.I. I. Acid Blue 45 or a copper phthalocyanine pigment having 1 to 5 phthalimidomethyl groups substituted on the phthalocyanine skeleton, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 83; I. Bat yellow 1, 3, 20, etc. are mentioned. These can be used alone or in combination.

  The amount of the colorant used is 0.1 to 60 parts by mass, preferably 0.5 to 50 parts by mass with respect to 100 parts by mass of the binder resin.

  In addition, as a charge control agent (that is, a negatively chargeable charge control agent) for controlling the toner used in the present invention to have a negative charge polarity, an organic metal complex or a chelate compound is effective, and a monoazo metal complex or acetylacetone metal Complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes can be used. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids, and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

On the other hand, as a charge control agent (that is, a positively chargeable charge control agent) when controlling the toner of the present invention to a positive charge polarity, a nigrosine dye; a modified product with a fatty acid metal salt or the like; tributylbenzidylammonium-1- Quaternary ammonium salts such as hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts that are analogs thereof and lake pigments thereof; triphenylmethane dyes and lake lake pigments thereof (As rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungstic molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.); amines and polyamine compounds; metal salts of higher fatty acids ; Acetylacetone metal complex; Dibutyl Dibutyltin oxide, dioctyltin oxide, diorganotin oxides such as dicyclohexyl tin oxide; dibutyl tin borate, dioctyl tin borate, diorgano tin borate such as such as dicyclohexyl tin borate is used. Regardless of whether the negatively chargeable charge control agent or the positively chargeable charge control agent is used, the amount used is 0.1 to 15 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the binder resin. It is.

A release agent can be added to the toner base particles in the present invention as required. For example, aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, paraffin wax, and Fischer-Tropsch wax or oxides thereof; waxes mainly composed of fatty acid esters such as carnauba wax and montanic ester wax; And those obtained by deoxidizing some or all of them. In addition, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brandic acid, eleostearic acid, and valinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvir alcohol, and seryl alcohol , Saturated alcohols such as merisyl alcohol, polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide; saturated fatty acid bisamides such as methylenebisstearic acid amide; unsaturated fatty acid amides such as ethylene bisoleic acid amide Aromatic bisamides such as N, N'-distearylisophthalic acid amide; Fatty acid metal salts such as zinc stearate; Waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene ; A partially esterified product of a fatty acid such as behenic acid monoglyceride and a polyhydric alcohol; a methyl esterified product having a hydroxyl group obtained by hydrogenation of vegetable oil or the like can also be used. The addition amount is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  The toner base particles used in the present invention are prepared by melting and kneading the above materials and kneading and pulverizing the toner particles to form toner particles; by dispersing the constituent materials in the binder resin solution and then spray drying the toner. A predetermined material is mixed with the monomer constituting the binder resin to obtain an emulsified suspension, followed by polymerization to obtain a toner.

The toner of the present invention contains one or more external additives. As the external additive used in the present invention, inorganic fine powders such as silica, alumina and titanium oxide can be suitably used. The inorganic fine powder preferably has a specific surface area (BET) of 20 to 400 m ² / g. Furthermore, the surface treated product of the inorganic fine powder can be used as an external additive. Examples of the surface treatment agent include a silane coupling agent, a titanium coupling agent, and a silicone oil. Preferably, the surface treatment agent is treated with a silane coupling agent or / and a silicone oil. You may surface-treat with 2 types. The amount of the fine powder added to the toner is 0.03 to 5 parts by mass, preferably 0.03 to 3 parts by mass with respect to 100 parts by mass of the toner.

The toner of the present invention can be obtained by adding (ie, adding externally) such an external additive to the toner base particles obtained by the above methods and mixing them. The toner of the present invention thus obtained is preferably a non-magnetic one-component toner.

  <Image Forming Apparatus> The image forming apparatus of the present invention using the above toner will be described below. The image forming apparatus of the present invention includes an image carrier that carries an electrostatic latent image, an exposure device that forms an electrostatic latent image on the image carrier by exposing the image carrier, and the toner. At least a toner carrier for transporting the toner to the image carrier, and a developing region is formed by bringing the toner carrier into contact with the image carrier, and the toner is electrostatically latent on the image carrier in the development region. And a developing device that visualizes the electrostatic latent image by electrically attaching it to the image to form a toner image.

  FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus of the present invention. The image forming apparatus of the present invention includes a photosensitive drum 1 as an image carrier for carrying an electrostatic latent image, a charging roller 5 as a charging means for charging the photosensitive drum 1, and an electrostatic latent image on the photosensitive drum 1. A laser scanner 6 as an exposure device for forming an image, a developing device 3 for developing an electrostatic latent image formed by the laser scanner 6 to form a toner image, and a transfer for transferring the obtained toner image to a transfer material A transfer roller 4 as a means and a cleaning device 17 that collects toner remaining on the photosensitive drum 1 after the transfer by the transfer roller 4 is performed.

  The developing device 3 is used for developing the electrostatic latent image formed on the photosensitive drum 1. In the present embodiment, as shown in FIG. 2, the photosensitive drum 1 and the developing device 3 are process cartridges that are detachable from the image forming apparatus main body, but may be a fixed installation type. A laser scanner 6 serving as an exposure apparatus irradiates the photosensitive drum 1 with laser light that is input to the image forming apparatus or controlled on / off according to an image signal such as a test pattern created inside the apparatus body. Then, an electrostatic latent image (digital latent image) is formed on the photosensitive drum 1. The exposure apparatus used in the present invention is not limited to a laser scanner, and an exposure apparatus such as an LED print head system or a liquid crystal shutter array system can also be applied.

  As a method for obtaining density gradation by modulating the image signal input to the exposure apparatus, an area gradation method such as laser light intensity modulation, error diffusion method, dither method, or the like is preferably used. Further, they may be combined. It is also preferable to perform multi-value recording by area gradation of one pixel using a PWM (pulse width modulation) method, and the image signal is changed at 256 gradation levels from 00h (white) to FF (black). Is also possible.

  At this time, as the surface potential of the photosensitive drum 1, when a negatively chargeable toner is used, the non-image portion potential (Vd) is preferably in the range of −500 to −800V, and an image capable of obtaining the maximum toner image density. The partial potential (Vl) is preferably in the range of −50 to −200V. Similarly, when positively charged toner is used, the non-image area potential (Vd) is preferably in the range of +500 to +800 V, and the image area potential (Vl) for obtaining the maximum toner image density is +50 to +200 V. A range is preferred.

  As shown in FIG. 1, the developing device 3 includes a developing container 11 containing a non-magnetic toner (one-component toner) 10 of a one-component developer, a developing roller 2, a developing blade 9, a toner supply roller 8, a stirring blade 12, and the like. It has the composition provided with.

The developing roller 2 has a multilayer structure in which an elastic layer including a base layer and a surface layer thereon is provided around a cylindrical body made of metal such as aluminum, an alloy thereof, or stainless steel. The base layer of the elastic layer is made of rubber such as butadiene acrylonitrile rubber (NBR), ethylene-propylene-diene polyethylene (EPDM), silicone rubber, urethane rubber, and the surface layer is made of ether urethane or nylon. Of course, the structure is not limited thereto, and a structure in which a foam such as sponge is used for the base layer and a rubber elastic layer is formed on the surface layer can be used. Or it is good also as a structure made into the single layer structure comprised only from rubber elastic layers, such as NBR, EPDM, and urethane rubber. In the present embodiment, the developing roller 2 is rotationally driven in the direction of arrow b in the figure by a developing roller driving source (not shown).

  Above the developing roller 2, a developing blade 9, which is a toner regulating member, is supported by the pressing plate 13 and is provided so that the vicinity of the free end is in contact with the outer peripheral surface of the developing roller 2 in surface contact. ing. The abutting direction of the developing blade 9 is a so-called counter direction in which the tip end side is located upstream of the abutting portion in the rotation direction of the developing roller 2.

  In this embodiment, the developing blade 9 is formed by bonding or injecting polyamide elastomer as the elastic member 9b to a phosphor bronze plate having spring elasticity as the metal thin plate 9a, and the elastic member 9b side is connected to the developing roller. 2 is in contact with the surface of the surface at a predetermined linear pressure. The pressure contact force of the developing blade 9 against the developing roller 2 is maintained by the metal thin plate 9a, and when the toner 10 is a negatively chargeable toner, for example, the chargeability to the toner 10 is imparted by the polyamide elastomer. The thin metal plate 9a is not particularly limited as long as it maintains the pressure contact force of the developing blade, and the elastic member 9b can be selected in consideration of the charging property of the toner. Further, it is not necessary to provide a charging member for the toner such as the elastic member 9b, and a metal thin plate 9a having spring elasticity such as a stainless steel thin plate or a phosphor bronze thin plate is used as it is, and this metal thin plate 9a is passed through the toner. A configuration that contacts the developing roller 2 may be used.

  The toner supply roller 8 preferably has a sponge structure or a fur brush structure in which fibers such as rayon or nylon are planted on the core metal from the viewpoint of supplying the toner to the developing roller 2 and stripping off the remaining toner. In the embodiment, an elastic roller provided with urethane foam on a core metal is used. The toner supply roller 8, which is an elastic roller, contacts the developing roller 2 and is rotated in the same direction as the developing roller 2, that is, in the direction of arrow c.

  When the electrostatic latent image formed on the photosensitive drum 1 is developed with toner, a developing high voltage that is a developing bias voltage is applied to the developing roller 2. The development high voltage is a DC voltage. The development high voltage of the electrostatic latent image formed under the above conditions includes the development high voltage value (Vdc) and the image portion potential (Vl) at which the maximum toner image density is obtained. The contrast potential | Vl−Vdc | (Vcont), which is the potential difference between the two, is suitable in the range of 50 to 400V.

  Further, since the toner regulated by the developing blade 9 and carried on the developing roller 3 is a non-magnetic one-component toner, the force that restrains the toner on the developing roller 3 is slightly different from the reflection force due to the charge of the toner. Since the van der Waals force only works, when the toner layer on the developing roller 3 becomes thick, the mirroring force for the toner on the upper layer of the toner layer becomes weak, so that the toner cannot be carried on the developing roller 3 and the toner is scattered. End up. Therefore, it is necessary to regulate the toner layer on the developing roller 3 thinly, but as a result, it may be difficult to obtain a sufficient image density. In such a case, it is possible to obtain an image density by setting the peripheral speed of the developing roller 3 faster than the peripheral speed of the photosensitive drum 1, and the peripheral speed ratio with respect to the peripheral speed of the photosensitive drum 1 is A range in which the peripheral speed of the developing roller 3 is 1.1 to 3 times is preferable.

  Here, in the image forming apparatus of the present invention, when the toner is a negatively chargeable toner, the surface layer of the photosensitive drum 1 as an image carrier, the toner base particles, and the triboelectric charge train of external additives are sequentially in the order from the minus side. It has the relationship of these.

(A) External additive, toner base particle, surface layer of photosensitive drum 1 (b) Toner base particle, external additive, surface layer of photosensitive drum 1 (c) Toner base particle, surface layer of photosensitive drum 1, external additive, In the image forming apparatus of the present invention, when the toner is a positively chargeable toner, the surface layer of the photosensitive drum 1 as the image carrier, the toner base particles, and the frictional charge train of the external additive have the following relationship in order from the plus side. It is characterized by having.

(D) External additive, toner base particle, surface layer of photosensitive drum 1 (e) Toner base particle, external additive, surface layer of photosensitive drum 1 (f) Toner base particle, surface layer of photosensitive drum 1, external additive toner base By maintaining the relationship of the frictional charge train of particles and external additives to the surface of the photosensitive drum as described above, even when the surface of the photosensitive drum and the toner are rubbed with each other in the contact development method, the toner is maintained at a normal charging polarity. In addition, the toner tribo can be prevented from being lowered, and the density gradation characteristics can be maintained satisfactorily. That is, when a negatively chargeable toner is used in the image forming apparatus of the present invention, if the relationship of (a) and (b) is established, the toner is rubbed by the surface of the photosensitive drum, so that the toner base particles and The external additive can maintain regular negative charging characteristics. When the relationship (c) is satisfied, the toner is rubbed by the surface of the photosensitive drum, so that the toner base particles stably maintain the negative charge characteristic and the external additive is positively charged. When the positively charged external additive performs the carrier-like function as in the two-component development system on the toner base particles, the toner base particles can be negatively charged more effectively.

  Further, when the positively chargeable toner is used in the image forming apparatus of the present invention, when the relationship (d) and (e) is satisfied, the toner is rubbed by the surface of the photosensitive drum, so that the toner base particles and The external additive can maintain regular positive charging characteristics. When the relationship (f) is established, the toner is rubbed by the surface of the photosensitive drum, so that the toner base particles are stably maintained in the positive charge characteristic and the external additive is negatively charged. When the negatively charged external additive performs the carrier-like function as in the two-component development system on the toner base particles, the toner base particles can be positively charged more effectively.

  Further, by setting the relationship between the toner base particles and the triboelectric charge train of the external additive to the photosensitive drum surface layer as described above (a) to (f), proper tribo can be imparted to the toner. Excess toner can be prevented from being transferred, toner consumption can be prevented from increasing, and line drawings can be prevented from scattering.

  In addition, the surface layer of the photosensitive drum, the toner base particles, and the external additive are appropriately selected so that the above relationships (a) to (f) are satisfied, and the image forming apparatus of the present invention is realized by using these in combination. can do.

  Further, as the conditions of the development high voltage of the electrostatic latent image in the cases (a) and (d), the potential difference between the development high voltage value (Vdc) and the image portion potential (Vl) at which the maximum toner image density can be obtained. The contrast potential | Vl−Vdc | (Vcont), which is a minute, is in the range of 50 to 400V, and the back contrast potential | Vd−Vdc that is the potential difference between the development high voltage value (Vdc) and the non-image portion potential (Vd) | (Vback) is suitable in the range of 50 to 500V.

  The conditions of the development high voltage of the electrostatic latent image in the cases (b) and (e) are the potential difference between the development high voltage value (Vdc) and the image portion potential (Vl) at which the maximum toner image density is obtained. In a range where a certain contrast potential | Vl−Vdc | (Vcont) is 50 to 400V, a back contrast potential | Vd−Vdc | (which is a potential difference between the development high voltage value (Vdc) and the non-image portion potential (Vd). Vback) is suitable in the range of 100 to 500V.

The conditions of the development high voltage of the electrostatic latent image in the cases (c) and (f) are the potential difference between the development high voltage value (Vdc) and the image portion potential (Vl) at which the maximum toner image density is obtained. In a range where a certain contrast potential | Vl−Vdc | (Vcont) is 50 to 400V, a back contrast potential | Vd−Vdc | (which is a potential difference between the development high voltage value (Vdc) and the non-image portion potential (Vd). Vback) is suitable in the range of 100 to 400V.

  Hereinafter, the photosensitive drum 1 as an image carrier used in the image forming apparatus of the present invention will be described. The photosensitive drum 1 of the present invention has a configuration in which a functional layer, a charge generation layer, and a charge transport layer as required are laminated on a conductive substrate (support). Examples of the material of the conductive substrate include metals such as aluminum, copper, nickel, silver or alloys thereof; conductive metal oxides such as antimony oxide, indium oxide, tin oxide, carbon fiber, carbon black, and graphite powder. What mixed resin molding is mentioned.

  In order to cover defects on the conductive substrate and to protect the conductive substrate, a conductive layer may be provided on the conductive substrate. For example, metal powder such as aluminum, copper, nickel and silver; conductive metal oxide such as antimony oxide, indium oxide and tin oxide; polymer conductive material such as polypyrrole, polyaniline and polymer electrolyte; carbon fiber and carbon black A graphite powder; or a conductive material such as a conductive powder whose surface is coated with these conductive materials, a thermoplastic resin such as an acrylic resin, a polyester resin, a polyamide resin, a polyvinyl acetate resin, a polycarbonate resin, or a polyvinyl butyral resin; , Polyurethane resins, phenol resins, epoxy resins and other thermosetting resins, photo-curing resins and other binder resins dispersed on the substrate, and additives added as necessary.

  In addition, a barrier layer such as polyamide, polyurethane, epoxy resin, or aluminum oxide may be provided between the conductive substrate and the photosensitive layer as necessary.

  Charge generation materials used in the charge generation layer include azo pigments such as Sudan Red and Diane Blue; quinone pigments such as pyrene, quinone and anthanthrone; quinocyanine pigments; perylene pigments; indigo pigments such as indigo and thioindigo and phthalocyanine pigments One kind or a plurality of other organic pigments may be mixed.

  A binder resin is added to the charge generation layer as necessary. Examples of the binder resin include thermoplastic resins such as acrylic resin, polyester resin, polyamide resin, polyvinyl acetate resin, polycarbonate resin, and polyvinyl butyral resin; thermosetting resins such as polyurethane resin, phenol resin, and epoxy resin; Etc.

  In forming the charge transport layer, generally, a solvent is added to the charge transport material and the binder resin to prepare a coating solution, which is coated on a conductive substrate on which the charge generation layer is formed by a coating means. Form. Examples of the material for the charge transport layer include hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylamine compounds, and the like.

  As the solvent used at this time, a solvent having good solubility in the binder resin and the charge transport agent is selected. Particularly good examples include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone; ethers such as diethyl ether and tetrahydrofuran; esters such as ethyl acetate and butyl acetate; hydrocarbons such as toluene and benzene; chlorobenzene And halogenated hydrocarbons such as dichloromethane.

As the binder resin for the charge transport layer, in addition to the polycarbonate in the present invention, for example, thermoplastic resins such as acrylic resin, polyester resin, polyamide resin, polyvinyl acetate resin, polycarbonate resin, polyvinyl butyral resin, polyvinyl benzal resin; Examples thereof include those dispersed in a binder resin such as a thermosetting resin such as a polyurethane resin, a phenol resin, and an epoxy resin, and those dispersed in a suitable solvent and applied. Furthermore, it is possible to add additives as required.

  The ratio of the charge transport agent to the binder resin is generally 20 to 70% by mass, particularly preferably 30 to 65% by mass, although it depends on the types of the binder resin and the charge transport material. If the ratio of the charge transport material is too small, sufficient sensitivity cannot be obtained. On the other hand, when the ratio of the charge transporting material is too large, the strength of the charge transporting layer that becomes the surface layer is lowered and easily damaged.

  Moreover, you may add lubricants, such as an inorganic filler and polyethylene, polyfluoroethylene, a silica, to a charge transport layer as needed. The ratio of the lubricant to the binder resin in the charge transport layer is 0.1 to 50% by mass, particularly preferably 1 to 30% by mass. Furthermore, it is also preferable to add additives as necessary, for example, a dispersion aid, silicone oil, leveling agent, metal soap, silane coupling agent and the like.

  In addition, as a charge transport layer that is preferably used in combination with a negatively chargeable toner, a mixture of one or more hydrazone compounds, stilbene compounds, and triarylamine compounds as a charge transport material is used. And a charge transport layer using a polycarbonate resin or a polyarylate resin as a binder resin.

  In addition, an additive such as an electron-withdrawing substance, an electron-donating substance, an ultraviolet absorber, or an antioxidant may be added to the charge generation layer and the charge transport layer as necessary.

  In the present invention, a protective layer may be further provided on the charge transport layer. The material constituting the protective layer is polyester, polyacrylate, polyethylene, polystyrene, polybutadiene, polycarbonate, polyamide, polypropylene, polyimide, polyamideimide, polysulfone, polyacryl ether, polyacetal, phenol, acrylic, silicone, epoxy, urea, allyl. Alkyd, butyral, phenoxy, phosphazene, acrylic-modified epoxy, acrylic-modified urethane, and acrylic-modified polyester resin. The thickness of the protective layer is preferably 0.2 to 10 μm.

  An additive such as an antioxidant may be further added to the protective layer for the purpose of improving the weather resistance. Further, conductive powder such as conductive tin oxide and conductive titanium oxide may be dispersed in the protective layer for the purpose of resistance control.

  Examples of the material constituting the protective layer that is preferably used in combination with the negatively charged toner include polyacrylate resins and polycarbonate resins.

  As a coating method of each layer used in the present invention, a dip coating method, a spray coating method, a roll coater coating method, a gravure coater coating method, or the like can be applied.

  As described above, according to the present invention, an electrostatic latent image formed by laser light that is ON / OFF controlled in accordance with an image signal is brought into contact with the image carrier with the toner carrier at a predetermined pressure. When the image is formed by the contact developing method, the relationship of the triboelectric charge train of the charge transport layer which is the surface layer of the photosensitive drum with respect to the toner is configured as described in (a) to (f) above. Even when the toner is rubbed, the toner can be maintained at a normal charging polarity, and the toner tribo can be prevented from being lowered, and the density gradation characteristics can be maintained well. A line image latent image such as a character image can be formed with an appropriate amount of toner, so that an increase in toner consumption can be prevented and scattering can be prevented. Further, reversal fogging is prevented, and it is possible to cope with a low running cost and a long life of the developing device.

  In the present invention, the triboelectric charging characteristics of the toner, toner base particles, external additive, and surface layer of the image carrier are measured by the following measuring method.

FIG. 6 shows a schematic diagram of a triboelectric charge measuring device. The apparatus includes a support table 201 inclined at 60 ° with respect to the horizontal, a contact powder storage member 203 for storing measurement contact powder 202, a measured object support plate 204 supported by the support table 201, A recovery container 205 for recovering the contact powder 202 supplied on the measurement object support plate 204 and an electrometer 206 (model 6514 manufactured by KEITHLEY) connected to the measurement object support plate 204 are configured. The contact powder 202 is poured from the contact powder storage member 203 into the measurement object 207 applied on the measurement object support plate 204, and the amount of electric charge generated by friction is displayed on the electrometer 206. In the present invention, the evaluation of the charge train characteristics between the toner and the surface layer of the image carrier is carried out by using a stainless steel plate having a thickness of 1 mm as the measurement object support plate 204 and the above-described charge transport layer and protective layer as the surface layer of the image carrier. As a measurement object 207, a sample is formed by dip coating and drying. Further, negatively charged toner and toner base particles of positively charged toner are prepared by adjusting the binder resin, colorant, charge control agent, release agent and the like, and the toner base particles and toner base particles are externally attached. The external additive to be added is used as the contact powder 202 to measure the toner base particles and the charge train of the external additive with respect to the object 207 to be measured. In addition, the measurement of the charging characteristics between the toner base particles and the external additive is performed using a toner base particle that is pressure-molded into a plate shape as the object to be measured 207 and using the external additive as the contact powder 202.

  The image density in the present invention is a value measured using a reflection densitometer RD918 manufactured by Macbeth. Specifically, it is formed by repeating a repetitive pattern in which 2 dots of the dither matrix composed of 4 dots × 4 dots shown in FIG. 7 are exposed, and repeating this repetitive pattern over the entire image forming area. A toner halftone pattern (FIG. 8) is output, and the density of five points (upper left, upper right, center, lower left, lower right) of the entire image is measured, and this average value is 2/16 gradations. Concentration. Similarly, using a repeating pattern in which 4 dots of the dither matrix composed of 4 dots × 4 dots shown in FIG. 9 are exposed and repeating this, the density of the five-point portion density average of the output image of the halftone image formed by repeating this is averaged. The value is 4/16 gradation density.

  Further, the fog generated in the image forming apparatus of the contact development type as in the present invention is a so-called reversal fog, so that it is hardly transferred to the transfer target. Therefore, a technique for directly collecting and evaluating the fog on the image carrier is used. To measure fog, the fog toner transferred on the image carrier is collected with a transparent substrate adhesive tape, and this sample tape and an unused adhesive tape to which nothing is attached as a reference tape are placed on a white paper. Attach, measure the reflectance of each, and subtract the reflectance of the sample tape from the reflectance of the reference tape to obtain the fog density. The reflectance is measured with TC-6DS manufactured by Tokyo Denshoku.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to these examples.

  <Example 1> The same image forming apparatus as that described in the embodiment of the present invention was used. Hereinafter, the image forming apparatus used in this embodiment will be described in detail with reference to FIG.

  As the developing roller 2, one having the following configuration was used. That is, an EPDM layer was formed as a base layer around a cored bar made of a steel rod plated on the surface, and an ether urethane layer was provided as a surface layer by adding carbon black as a conductive agent to adjust the resistance. .

  Next, the photosensitive drum 1 that is an image carrier will be described. First, 5 parts by mass of 6-66-610-12 quaternary polyamide copolymer is mixed with 70 parts by mass of methanol and 25 parts by mass of butanol on an aluminum cylinder having a diameter of 30 mm (diameter) × 260.5 mm (length). The solution dissolved in 1 was applied by dipping and dried to provide an undercoat layer having a thickness of 0.65 μm.

  Next, 5 parts by mass of an oxytitanium phthalocyanine crystal having diffraction peaks 2θ ± 0.2 ° in X-ray diffraction having strong peaks at 9.0 °, 14.2 °, 23.9 °, and 27.1 °. Then, 5 parts by mass of polyvinyl butyral resin was added to a solution dissolved in 100 parts by mass of cyclohexanone, and dispersed with a sand mill using glass beads having a diameter of 1 mmφ (diameter). The dispersion was diluted by adding 200 parts by mass of ethyl acetate, applied onto the undercoat layer, and then dried at 80 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.25 μm.

Furthermore, 10 parts by mass of a polycarbonate resin and 10 parts by mass of a charge transport material of a triarylamine compound represented by the following general formula (I) are dissolved in 80 parts by mass of methylene chloride, and the resulting solution is subjected to the above dipping method. It was coated on the charge generation layer and dried at 110 ° C. for 1 hour to form a charge transport layer having a thickness of 24 μm, and a multilayer electrophotographic photosensitive member as an image carrier was prepared. This electrophotographic photosensitive member is referred to as a photosensitive drum A.

Next, the negatively charged toner 10 used in this embodiment will be described. 100 parts by mass of a polyester resin, 5 parts by mass of carbon black, 3 parts by mass of low molecular polyethylene, and 2 parts by mass of a monoazo metal complex (negative charge control agent) represented by the following general formula (II) are mixed using a Henschel mixer. The mixture was melt kneaded with a twin screw extruder. This was coarsely pulverized with a hammer mill, then finely pulverized with a jet mill, and further subjected to air classification to obtain negatively charged toner base particles as a classified product having an average particle diameter of 7.5 μm. This is toner base particle A. Specific surface area is 300m ²
1 part by weight of hydrophobic silica fine powder (hereinafter referred to as external additive A) obtained by surface-treating 100 parts by weight of silica / g with 10 parts by weight of hexamethyldisilazane and 17 parts by weight of dimethyl silicone oil Was added externally to 100 parts by mass of the toner base particles A to obtain a negatively chargeable toner. This negatively charge characteristic toner is referred to as toner A.

（式中、Ｘはハロゲン（塩素原子）、ＭｅはＣｒ原子を示す。）

(In the formula, X represents a halogen (chlorine atom), and Me represents a Cr atom.)

  The charging characteristics of the toner base particles A and the external additive A constituting the toner A produced as described above to the photosensitive drum A were examined by the following method. The charge transport layer, which is the surface layer of the photosensitive drum A, is applied as the measurement object 207 on the measurement object support plate 204 of the triboelectric charge measuring device of FIG. In addition, the triboelectric charging characteristics of the toner base particles A and the external additive A with respect to the surface layer of the photosensitive drum A of the present example were used as the external additive A.

  When measuring the charging characteristics of the toner base particles A and the external additive A with respect to the photosensitive drum A using the photosensitive drum, the surface of the photosensitive drum and the toner base particles A or the external additive A are rubbed to form a toner base. The particle A or external additive A is examined by measuring the triboelectric charge polarity.

  Further, the relationship between the charging characteristics of the toner base particles A and the external additive A was measured by the following method. The measured particle support plate 204 placed in a flat press molding machine is filled with the toner base particles A as a powder, and the toner particles A are molded into a plate shape on the measured sample support plate 204 by pressurizing it. The object to be measured 207 was obtained. The contact powder 202 was used as the external additive A for the object to be measured 207 obtained by press molding the toner base particles A, and the triboelectric charging characteristics of the external additive A with respect to the toner base particles A were examined.

  As a result, the charge transport layer of the photosensitive drum A was positively charged due to friction with the toner base particles A and the external additive A. Further, the external additive A used for the toner A was negatively charged with respect to the toner base particles A. In other words, the relationship between the triboelectric charge trains was external additive A, toner base particle A, and photosensitive drum A surface layer in order from the minus side. Then, the charged polarity of the surface layer of the photosensitive drum A was a positive plus of a different polarity with respect to the toner charged with a minus frictional charge by the elastic developing blade and the developing roller in the developing device.

Next, the process cartridge of the laser jet 4050 manufactured by Hewlett-Packard Company was modified to the configuration shown in FIG. 1 to obtain an image forming apparatus capable of image formation by the contact development method. That is, the elastic developing blade made of a rubber material was changed to a developing blade 9 composed of a metal thin plate 9a made of a phosphor bronze plate and an elastic member 9b made of a polyamide elastomer. Further, the developing sleeve including the fixed magnet was changed to the developing roller 2 provided with a resistance-adjusted ether urethane layer containing EPDM as a base layer and carbon black as a conductive agent as a surface layer. Further, a part of the developing container was processed so that the toner supply roller 8 made of an elastic roller provided with urethane foam was brought into contact with the developing roller 2 so that it could rotate in the same direction as the developing roller 2. The developing device 3 was replenished with 120 g of the toner A. Further, the photosensitive drum was changed to the photosensitive drum A, and a durability evaluation test was performed using a contact development method.

  In the endurance test evaluation, as the configuration setting conditions, the process speed was set to 94.2 mm / sec, the peripheral speed of the developing roller 2 was set to 160.1 mm / sec, and the peripheral speed of the toner supply roller 8 was 120.mm. It was set to 0 mm / sec. Further, the contact pressure of the developing blade 9 was set to be 25 g / cm in terms of linear pressure. In such a setting, the toner tribo carried on the developing roller 2 was −20 to −40 μC / g. As the potential setting, the non-image portion potential (Vd) on the surface of the photosensitive drum was set to −700 V, and the image portion potential (Vl) at which the maximum toner image density was obtained was set to −120 V. Further, the development high voltage value (Vdc) applied to the developing roller 2 was set to −370V, and the contrast potential | Vl−Vdc | (Vcont) was set to 250V.

  In the embodiment of the present invention, an image with an image ratio of 3% is continuously printed using the image forming apparatus, and the density of 16/16 gradation image and 4/16 gradation image is set every 1000 sheets. Measured by the method described. In addition, a character image was printed and the degree of scattering was visually evaluated.

  Further, the amount of toner used was measured by measuring the weight of the developing device before and after image formation. Further, a sample was collected by taping the fog toner adhering to the photosensitive drum, and the fog density was measured by the method described in the embodiment of the present invention. Table 1 shows the results of performing the above evaluations every 1000 prints and finally conducting a durability evaluation test of 5000 sheets. The ideal values of 2/16 gradation image density and 4/16 gradation image density in this embodiment are 0.15 and 0.30, respectively. Moreover, each symbol in character scattering evaluation of Table 1 shows the following evaluation, respectively.

  The toner scattering (state of FIG. 10B) to the periphery of the character when the “electric” character pattern shown in FIG. 10A was printed on plain paper was visually evaluated.

  ○: Almost no occurrence.

  Δ: Slight scattering is observed.

  X: A remarkable scattering is seen.

  As shown in Table 1, in the photosensitive drum A of this embodiment, the density of the gradation image is slightly lower than the ideal density, while maintaining a stable density, and the scattering of the character image is observed through the durability evaluation test. There wasn't. Further, the fog was maintained at a low density up to the 5000th sheet, and there was no problem without greatly affecting the amount of toner used.

  As described above, according to the present embodiment, the electrostatic latent image formed by the laser beam that is ON / OFF controlled according to the image signal is brought into contact with the developing roller at a predetermined pressure against the photosensitive drum. When forming an image by the contact development method, the relationship between the toner base particles constituting the negative charge characteristic toner and the external additive and the triboelectric charge train of the charge transport layer which is the surface layer of the photosensitive drum is as follows. By adjusting the order of the mother particles and the surface of the photosensitive drum, even when the surface of the photosensitive drum and the toner are rubbed, the toner can be maintained at a normal negative charging polarity, and the toner tribo can be prevented from being lowered. It becomes possible to maintain the tonal characteristics well. A line image latent image such as a character image can be formed with an appropriate amount of toner, and an increase in toner consumption is prevented and scattering is also prevented. Further, reversal fogging is prevented, and it is possible to cope with a low running cost and a long life of the developing device.

  In this embodiment, the laser scanner is used as the exposure apparatus. However, the present invention is not limited to this, and an exposure apparatus such as an LED print head system or a liquid crystal shutter array system is also applicable.

  In the present embodiment, the photosensitive drum and toner as described above are used. However, the present invention is not limited to this, and the relationship of the triboelectric charge train is from the minus side to the order of external additive, toner base particles, and photosensitive drum surface layer. It is of course possible to appropriately select and use toner base particles, external additives and charge transport layers having such triboelectric charging characteristics.

  In addition, the toner base particles of the present example were prepared by kneading and pulverization. However, the present invention is not limited to this. Other than that, the constituent materials are dispersed in a binder resin solution, and then the toner base particles are spray-dried. A toner base particle is prepared by a polymerization method in which a predetermined material is mixed with a monomer that constitutes the binder resin to obtain an emulsion suspension and then polymerized to obtain toner base particles. May be.

  In this embodiment, a negatively chargeable toner is used as the toner, and a material exhibiting a positive triboelectric charge characteristic for each of the negatively charged toner base particles and the external additive is used as the charge transport layer. In the case of using characteristic toner base particles, a positive charge characteristic external additive is selected, and a material that exhibits negative triboelectric charge characteristics for each of the toner base particles and the positive charge characteristic external additive as the charge transport layer of the photosensitive drum By using, as in the principle described above, the toner tribo is prevented from being lowered, and the above-described effects can be obtained.

In addition, a protective layer may be further laminated on the charge transport layer, and a photosensitive drum having durability against surface abrasion or generation of scratches due to rubbing may be used. For example, 100 parts by mass of antimony-containing tin oxide fine particles having an average particle size of 0.02 μm, 100 parts by mass of a curable acrylic monomer, 0.1 part by mass of 2-methylthioxanthone as a photopolymerization initiator, and 300 parts by mass of toluene are mixed. Then, it is dispersed for 96 hours by a sand mill device to prepare an adjustment liquid for the protective layer. The protective layer adjusting solution is formed on the charge transport layer of the photosensitive drum A by spray coating, dried, and then irradiated with ultraviolet light at a light intensity of 80 mW / cm ² for 20 seconds with a high-pressure mercury lamp. It is also possible to use a protective layer having a thickness of 5 μm. By providing the protective layer, it is possible to obtain a photosensitive drum that is strong against abrasion and scratches, so that it is possible to improve the durability of the photosensitive drum and to further cope with low running costs.

<Comparative Example 1> In this example, a charge transport layer serving as a surface layer of the photosensitive drum was manufactured by the following formulation. An intermediate coating for a charge transport layer is prepared by dissolving 10 parts by weight of a polycarbonate resin and 10 parts by weight of a charge transport material of the triarylamine compound represented by the above general formula (I) in 40 parts by weight of monochlorobenzene and 20 parts by weight of dichloromethane. A liquid was obtained. Next, 15 parts by mass of a dispersion prepared by dispersing 120 parts by mass of monochlorobenzene, 30 parts by mass of polytetrafluoroethylene particles and 1.8 parts by mass of comb-type fluorine-based graft polymer with a ball mill was added to the intermediate coating for the charge transport layer. In addition to the solution, a coating solution for a charge transport layer was obtained.

  The charge transport layer coating liquid is applied as a measurement object 207 on the measurement object support plate 204 of the triboelectric charge measuring device of FIG. 6 and dried, and the toner base particles A used in Example 1 are the contact powder 202. Using the additive A as an external additive A, the triboelectric charging characteristics of the charge transport layer of this example with respect to the toner base particles A and the external additive A were examined. As a result, the charge transport layer in the present comparative example was negatively charged by friction with respect to the toner base particles A and positively charged by friction with respect to the external additive A. That is, the relationship between the triboelectric charge trains was the external additive A, the charge transport layer, and the toner base particles A in order from the minus side.

  This charge transport layer coating solution was applied by dipping on the cylinder on which the undercoat layer and the charge generation layer of Example 1 were laminated, and dried at 110 ° C. for 1 hour, whereby a charge transport layer having a thickness of 24 μm was formed. Then, a multilayer electrophotographic photosensitive member was produced. This electrophotographic photosensitive member is referred to as a photosensitive drum B. The surface layer of the photosensitive drum B had the same negative polarity as that of the negatively charged toner A in the developing device.

  The photosensitive drum B and the toner A were applied to the image forming apparatus used in Example 1, and a durability evaluation test was performed in the same manner as in Example 1. The results are shown in Table 1.

  As shown in Table 1, in the comparative example 1, as the durability evaluation is advanced, the density of the 2/16 gradation image of 16 gradations and the density of the 4/16 gradation image increase, and the gradation image at the time of printing 5000 sheets The density has far exceeded the ideal image density. In addition, the scattering of character images also worsened as the durability evaluation progressed. The fog density is as high as 3 to 4 times that in the first embodiment, and as a result, the amount of toner used is increased. Compared with the first embodiment, the amount of toner corresponding to about 1000 sheets when printing 5000 sheets is increased. It resulted in consumption.

  In this example, the gradation image density, toner usage, and fog density in the durability evaluation test were almost the same as those in Example 1 from the initial stage until 2000 sheets were printed. It is considered that the external additive A, which is negatively charged by the surface of the photosensitive drum B, coats the toner base particles A so that the toner A has normal negative charging characteristics. However, as the developing device is repeatedly driven, the external additive A gradually leaves the toner base particle A or is embedded in the surface of the toner base particle A, so that it is difficult to obtain the negative charging characteristic of the external additive A. Further, the toner base particles A are positively charged by the surface of the photosensitive drum B, so that the tribo is lowered, and it is considered that the gradation image density, the toner usage amount, and the fog density are hindered.

〈実施例２〉本実施例では、像担持体として実施例１で説明した感光ドラムＡを用い、負帯電特性トナーとして、実施例１で説明したトナー母粒子Ａ１００質量部に、比表面積が
１１０ｍ²／ｇの酸化チタン１００質量部をイソブチルトリメトキシラン１７質量部で表
面処理して得られる疎水性酸化チタン微粉体（以下、これを外添剤Ｂと称す）１．３質量部を外添して得られる負帯電特性トナーを用いた。この負帯電特性トナーをトナーＢとする。

<Example 2> In this example, the photosensitive drum A described in Example 1 was used as an image carrier, and the specific surface area was 110 m as the negative charging characteristic toner in 100 parts by mass of toner base particles A described in Example 1. Hydrophobic titanium oxide fine powder (hereinafter referred to as external additive B) obtained by surface-treating 100 parts by mass of ² / g of titanium oxide with 17 parts by mass of isobutyltrimethoxylane is externally added. The negatively chargeable toner obtained in this way was used. This negatively chargeable toner is referred to as toner B.

  Using the triboelectric charge measuring device shown in FIG. 6, the charging characteristics of the external additive B with respect to the photosensitive drum A and the toner base particles A were examined in the same manner as in Example 1. As a result, the external additive B The toner was negatively charged due to friction with the charge transport layer of A, and positively charged with respect to the toner base particles A. That is, the relationship between the triboelectric charge train was toner base particle A, external additive B, and photosensitive drum A surface layer in order from the minus side. Further, the surface layer of the photosensitive drum A has a positive charging polarity of a different polarity with respect to the toner B of a negative charging polarity in the developing device.

  An image in which the toner B is supplied to a process cartridge of a laser jet 4050 manufactured by Hewlett-Packard Co. modified so that the contact development method can be performed in the same manner as in the first embodiment, and the photosensitive drum is changed to the photosensitive drum A. Using the forming apparatus, a durability evaluation test by printing 5000 sheets was performed in the same manner as in Example 1. That is, an image with an image ratio of 3% was continuously printed, and the density of a 16 gradation 2/16 gradation image and a 4/16 gradation image was measured every 1000 sheets. In addition, a character image was printed, and the degree of scattering of the character image was visually evaluated. Further, the amount of toner used was measured by measuring the weight of the developing device before and after image formation. Further, the fog density was measured by collecting a sample by taping the fog toner adhering to the photosensitive drum. Table 2 shows the results of performing the above evaluations every 1000 prints and finally conducting a durability evaluation test of 5000 sheets. Note that the ideal values of the 2/16 gradation image density and the 4/16 gradation image density in this embodiment are the same as those in Embodiment 1, and are 0.15 and 0.30, respectively.

  As shown in Table 2, in the present example, while the density of the gradation image was slightly lower than the ideal density, the character image was not scattered through the durability evaluation test while maintaining a stable density. Further, the fog was maintained at a low density up to the 5000th sheet, and there was no problem without greatly affecting the amount of toner used.

  As described above, according to the present embodiment, the relationship between the toner base particles constituting the negative charge characteristic toner and the external additive and the triboelectric charge train of the charge transport layer that is the surface layer of the photosensitive drum is determined from the negative side. In the order of the external additive and the photosensitive drum surface layer, even when the surface of the photosensitive drum and the toner are rubbed, the toner can be maintained at a normal negative charging polarity and the toner tribo can be prevented from being lowered. It is possible to maintain the density gradation characteristics well. An image can be formed with an appropriate toner amount even for a line image latent image such as a character image, and an increase in toner consumption is prevented, and scattering of the character image is also prevented. Further, reversal fogging is prevented, and it is possible to cope with a low running cost and a long life of the developing device.

  In this embodiment, the photosensitive drum and the toner as described above were used, but the present invention is not limited to this. The relationship between the triboelectric charge train is from the minus side to the order of the toner base particles, the external additive, and the photosensitive drum surface layer. It is of course possible to appropriately select and use such toner base particles, external additives, charge transport layers, and external additives.

  In this embodiment, a negatively chargeable toner is used as the toner, and a material exhibiting a positive triboelectric charge characteristic for each of the negatively charged toner base particles and the external additive is used as the charge transport layer. In the case of using characteristic toner base particles, a positive charge characteristic external additive is selected, and a material that exhibits negative triboelectric charge characteristics for each of the toner base particles and the positive charge characteristic external additive as the charge transport layer of the photosensitive drum In the same manner, the decrease in toner tribo is similarly suppressed, and the above-described effects can be obtained.

  <Comparative Example 2> In this example, a durability evaluation test was performed in the same manner as in Example 2 except that the photosensitive drum B was used as the image carrier.

  The triboelectric charging characteristics of the charge transport layer, which is the surface layer of the photosensitive drum B, with respect to the toner base particles A and the external additive B were performed as follows. A coating liquid for the charge transport layer of the photosensitive drum B is applied as a measurement object 207 on the measurement object support plate 204 shown in FIG. 6 and dried, and the contact powder 202 is used as the toner base particles A and the external additive B. The triboelectric charging characteristics of the charge transport layer of this example with respect to the toner base particles A and the external additive B were examined. As a result, the charge transport layer in Comparative Example 2 was negatively charged with respect to the toner base particles A and the external additive B. Further, from Example 2 above, the relationship of the frictional charge train between the external additive B and the toner base particles A is in the order of the toner base particles A and the external additive B from the minus side. Therefore, the relationship between the triboelectric charge trains was in the order of the charge transport layer, the toner base particles A, and the external additive B in order from the minus side. Further, the surface layer of the photosensitive drum B had a negative charge polarity with a different polarity with respect to the toner B with a negative charge polarity in the developing device.

  The evaluation results are shown in Table 2. In Comparative Example 2, as the durability evaluation was advanced, the density of the gradation image increased, and the fog density was high from the beginning. As a result, the amount of toner used increased, and toner was lost between 2000 and 3000 sheets, and the evaluation test could not be continued. This is considered because the toner base particles A and the external additive B are positively charged by the surface of the photosensitive drum B, and the normal negative charging characteristic as a toner cannot be obtained. In addition, the scattering of character images also worsened as the durability evaluation progressed.

〈実施例３〉本実施例では、像担持体として実施例１で説明した感光ドラムＡを用い、負帯電特性トナーとして、実施例１で説明したトナー母粒子Ａ１００質量部に、一次粒径が２００ｎｍの酸化チタン微粉体（以下、これを外添剤Ｃと称す）１質量部を外添して得られる負帯電特性トナーを用いた。この負帯電特性トナーをトナーＣとする。

<Embodiment 3> In this embodiment, the photosensitive drum A described in Embodiment 1 is used as the image carrier, and the primary particle diameter is 100 parts by weight of the toner base particles A described in Embodiment 1 as the negative charging toner. A negatively chargeable toner obtained by externally adding 1 part by mass of 200 nm titanium oxide fine powder (hereinafter referred to as external additive C) was used. This negatively chargeable toner is referred to as toner C.

  As in the above examples, the charging characteristics of the external additive C with respect to the photosensitive drum A and the toner base particles A were examined using the triboelectric charge measuring device shown in FIG. The toner was positively charged by friction with the charge transport layer of A, and positively charged with respect to the toner base particles A. Further, from Example 1 above, the relationship of the triboelectric charge train between the toner A and the surface of the photosensitive drum A is in order of the toner base particles A and the surface of the photosensitive drum A from the minus side. That is, the relationship between the triboelectric charge train was toner base particle A, photosensitive drum A surface layer, and external additive C in order from the minus side. Further, the surface layer of the photosensitive drum A has a positive charging polarity of a different polarity with respect to the toner C having a negative charging polarity in the developing device.

  The evaluation results are shown in Table 2. Note that the ideal values of the 2/16 tone image density and the 4/16 tone image density in this embodiment are 0.15 and 0.30, respectively, as in the first embodiment.

  As shown in Table 3, in this example, the gradation image maintained a stable density at a value close to the ideal density, and no scattering of the character image was observed through the durability evaluation. In addition, although the fog slightly increased at the 5000th sheet, the density before 4000 sheets was maintained at a low density, and there was no problem without greatly affecting the amount of toner used. This is because the toner base particles A are negatively charged due to friction with the surface of the photosensitive drum A, whereas the external additive C is positively charged due to friction with the surface of the photosensitive drum A. It is considered that the additive C is a result of further negatively charging the toner base particle A by performing the carrier function as it is in the two-component development system on the toner base particle A.

  As described above, according to the present embodiment, the relationship between the toner base particles constituting the negative charge characteristic toner and the external additive and the triboelectric charge train of the charge transport layer that is the surface layer of the photosensitive drum is determined from the negative side. In this order, the surface layer of the photosensitive drum and the external additive keep the toner mother particles at a regular negative charge polarity by the action of the external additive even when the surface of the photosensitive drum is rubbed with the toner. The decrease can be prevented, and the density gradation characteristics can be maintained well. An image can be formed with an appropriate toner amount even for a line image latent image such as a character image, and an increase in toner consumption is prevented, and scattering of the character image is also prevented. Further, reversal fogging is prevented, and it is possible to cope with a low running cost and a long life of the developing device.

  In this embodiment, the photosensitive drum and toner as described above were used. However, the present invention is not limited to this. The relationship between the triboelectric charge train is from the minus side to the order of toner mother particles, photosensitive drum surface layer, and external additive. It is of course possible to appropriately select and use such toner base particles, external additives and charge transport layers.

  In this embodiment, the toner added with one kind of external additive is used. However, the external additive of this embodiment has the triboelectric charge series characteristics with the surface of the photosensitive drum as described in the first and second embodiments. Even if it is used in combination with the external additive, it can be used without any problem and the same effect can be obtained.

  <Comparative Example 3> In this example, a durability evaluation test was performed in the same manner as in Example 2 except that the photosensitive drum B was used as the image carrier.

The triboelectric charging characteristics of the charge transport layer, which is the surface layer of the photosensitive drum B, with respect to the external additive C were performed as follows. The coating liquid for the charge transport layer of the photosensitive drum B is applied as the measurement object 207 on the measurement object support plate 204 shown in FIG. 6, dried, and the contact powder 202 is used as the external additive C. The triboelectric charging characteristics of the charge transport layer with respect to the external additive C were examined. As a result, the charge transport layer in Comparative Example 3 was negatively charged by friction with respect to the external additive C. The relationship between the charge transport layer and the toner base particles A used in the toner C is in the order of the charge transport layer and the toner base particles A from the minus side as described in Comparative Example 1. Further, from Example 3 above, the relationship of the frictional charge train between the external additive C and the toner base particles A is the order of the toner base particles A and the external additive C from the minus side. Accordingly, the relationship of the triboelectric charge train including the external additive C is in the order of the charge transport layer, the toner base particles A, and the external additive C in this order from the minus side. Further, the surface layer of the photosensitive drum B had the same negative polarity with respect to the negatively charged toner C in the developing device.

  The evaluation results are shown in Table 3. In Comparative Example 3, the density of the gradation image increased immediately after the start of the durability evaluation test, and the fog density was high from the beginning. As a result, the amount of toner used increased, and toner was lost between 2000 and 3000 sheets, and the evaluation test could not be continued. This is considered because the toner base particles A and the external additive B are positively charged by the surface of the photosensitive drum B, and the normal negative charging characteristic as a toner cannot be obtained. Also, the scattering of the character image was bad immediately after the start of durability evaluation.

〈実施例４〉本実施例では、像担持体として実施例１で説明した感光ドラムＡを用い、負帯電特性トナーとして、実施例１で説明したトナー母粒子Ａ１００質量部に、比表面積が１３０ｍ²／ｇのシリカ１００質量部をイソブチルメトキシラン５質量部で表面処理して
得られる疎水性シリカ微粉体（以下、これを外添剤Ｄと称す）１質量部を外添して得られる負帯電特性トナーを用いた。この負帯電特性トナーをトナーＤとする。

<Embodiment 4> In this embodiment, the photosensitive drum A described in Embodiment 1 is used as the image carrier, and the specific surface area is 130 m on the basis of 100 parts by mass of the toner base particles A described in Embodiment 1 as the negatively charged toner. ^A negative silica powder obtained by externally adding 1 part by mass of hydrophobic silica fine powder (hereinafter referred to as external additive D) obtained by surface-treating 100 parts by mass of ² / g silica with 5 parts by mass of isobutyl methoxylane. A charge characteristic toner was used. This negatively chargeable toner is referred to as toner D.

  Similar to the above embodiment, the triboelectric charge measuring device shown in FIG. 6 was used to examine the charging characteristics of the external additive D with respect to the photosensitive drum A and the toner base particles A. The toner was negatively charged due to friction with the charge transport layer, and the toner base particles A were negatively charged. Further, from Example 1 above, the relationship between the toner base particles A and the surface layer of the photosensitive drum A is in the order of the toner base particles A and the surface layer of the photosensitive drum A from the minus side. Therefore, the relationship between the triboelectric charge train was the external additive D, the toner base particles A, and the photosensitive drum A surface layer in order from the minus side. Further, the surface layer of the photosensitive drum A had a different positive charge polarity with respect to the toner D having a negative charge polarity in the developing device.

  An image in which the toner D is supplied to the process cartridge of a laser jet 4050 manufactured by Hewlett-Packard Co. modified so that the contact development method can be performed in the same manner as in Example 1, and the photosensitive drum is changed to the photosensitive drum A. Using the forming apparatus, a durability evaluation test by printing 5000 sheets was performed in the same manner as in Example 1.

  The evaluation results are shown in Table 4. Note that the ideal values of the 2/16 gradation image density and the 4/16 gradation image density in this embodiment are the same as those in Embodiment 1, and are 0.15 and 0.30, respectively.

  As shown in Table 4, in the present example, while the density of the gradation image was slightly lower than the ideal density, the character image was not scattered through the durability evaluation test while maintaining a stable density. Further, the fog was maintained at a low density up to the 5000th sheet, and there was no problem without greatly affecting the amount of toner used.

  As described above, according to the present embodiment, the relationship between the toner base particles constituting the negative charge characteristic toner and the external additive, and the triboelectric charge train of the charge transport layer which is the surface layer of the photosensitive drum is determined from the negative side. The toner base particles and the photosensitive drum surface layer in this order can maintain the toner at a regular negative charging polarity and prevent the toner tribo from being lowered, even when the photosensitive drum surface and the toner are rubbed. It is possible to maintain the density gradation characteristics well. An image can be formed with an appropriate toner amount even for a line image latent image such as a character image, and an increase in toner consumption is prevented and scattering is also prevented. Further, reversal fogging is prevented, and it is possible to cope with a low running cost and a long life of the developing device.

  <Comparative Example 4> In this example, a durability evaluation test was performed in the same manner as in Example 4 except that the photosensitive drum B was used as the image carrier.

  The triboelectric charging characteristics of the charge transport layer, which is the surface layer of the photosensitive drum B, with respect to the external additive D were measured as follows. On the measurement object support plate 204 shown in FIG. 6, the photosensitive drum object to be measured 207 is applied and dried, and the contact powder 202 is used as the external additive D described above, and the external additive D of the charge transport layer in this example. The triboelectric charging characteristics with respect to were investigated. As a result, the charge transport layer in Comparative Example 4 was negatively charged by friction with respect to the external additive D. As described in Comparative Example 1, the relationship between the charge transport layer and the toner base particles A used for the toner D is the relationship between the charge transport layer and the toner base particles A from the minus side. Further, from Example 4 above, the relationship of the triboelectric charge train between the external additive D and the toner base particles A is in the order of the external additive D and the toner base particles A from the minus side. Therefore, the relationship of the triboelectric charge train including the external additive D is the charge transport layer, the external additive D, and the toner base particles A in order from the minus side. Further, the surface layer of the photosensitive drum B had the same negative polarity of the charging polarity with respect to the toner D having a negative charging polarity in the developing device.

  The evaluation results are shown in Table 4. In Comparative Example 4, as the durability evaluation was advanced, the density of the gradation image increased, and the fog density was high from the beginning. As a result, the amount of toner used increased, and toner was lost between 2000 and 3000 sheets, and the evaluation test could not be continued. It is considered that this is because the toner base particles A and the external additive D are positively charged by the surface of the photosensitive drum B, and a normal negative charging characteristic as a toner cannot be obtained. In addition, the scattering of character images also worsened as the durability evaluation progressed.

  Further, even in a toner using two or more external additives in combination, it is necessary that at least one external additive satisfies the relationship (a), (b), or (c). Thus, the same effect can be obtained.

  Further, in the case where the positively chargeable toner is used in the image forming apparatus of the present invention, the relationship between the surface layer of the image carrier and the toner base particles constituting the positively chargeable toner and the externally charged additive from the plus side ( a) external additive, toner base particles, surface layer of photosensitive drum 1, (b) toner base particles, external additive, surface layer of photosensitive drum 1, (c) toner base particles, surface layer of photosensitive drum 1, external additive By setting the order, the same effect as described above can be obtained.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Developing roller 3 Developing apparatus 4 Transfer roller 5 Charging roller 6 Exposure apparatus 8 Toner supply roller 9 Elastic developing blade 10 Toner 17 Process cartridge

Claims (91)

  An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more external additives At least a toner carrying member for carrying a negatively charged toner having a negative charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region to form a toner image; The image forming apparatus characterized in that the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is from the minus side to the external additive, toner base particles, and the surface layer of the image carrier. .   The image forming apparatus according to claim 1, wherein the surface layer of the image carrier is a charge transport layer.   The image forming apparatus according to claim 1, wherein a surface layer of the image carrier is a protective layer.   The image forming apparatus according to claim 1, wherein the toner is a non-magnetic one-component toner.   The image forming apparatus according to claim 1, wherein the electrostatic latent image is a digital latent image.   The image forming apparatus according to claim 1, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relationship of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a different positive charge polarity with respect to the negative charge polarity in the developing device of the toner. The image forming apparatus according to any one of claims 1 to 6.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more external additives At least a toner carrying member for carrying a negatively charged toner having a negative charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region to form a toner image; The image forming apparatus characterized in that the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in order from the minus side to the toner base particles, the external additive, and the surface layer of the image carrier. .   The image forming apparatus according to claim 8, wherein the surface layer of the image carrier is a charge transport layer.   The image forming apparatus according to claim 8, wherein a surface layer of the image carrier is a protective layer.   The image forming apparatus according to claim 8, wherein the toner is a non-magnetic one-component toner.   The image forming apparatus according to claim 8, wherein the electrostatic latent image is a digital latent image.   The image forming apparatus according to claim 8, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relationship of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a different positive charge polarity with respect to the negative charge polarity in the developing device of the toner. The image forming apparatus according to any one of claims 8 to 13.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more external additives At least a toner carrying member for carrying a negatively charged toner having a negative charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region to form a toner image; The image forming apparatus characterized in that the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in order of the toner base particles, the surface layer of the image carrier, and the external additive from the minus side. .   The image forming apparatus according to claim 15, wherein the surface layer of the image carrier is a charge transport layer.   The image forming apparatus according to claim 15, wherein a surface layer of the image carrier is a protective layer.   The image forming apparatus according to claim 15, wherein the toner is a non-magnetic one-component toner.   The image forming apparatus according to claim 15, wherein the electrostatic latent image is a digital latent image.   The image forming apparatus according to claim 15, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relationship of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a different positive charge polarity with respect to the negative charge polarity in the developing device of the toner. The image forming apparatus according to any one of claims 15 to 20.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more external additives At least a toner carrier for carrying a positively charged toner having a positive charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region to form a toner image; The image forming apparatus characterized in that the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is from the plus side in the order of the external additive, toner base particles, and the surface layer of the image carrier. .   The image forming apparatus according to claim 22, wherein a surface layer of the image carrier is a charge transport layer.   The image forming apparatus according to claim 22, wherein a surface layer of the image carrier is a protective layer.   The image forming apparatus according to any one of claims 22 to 24, wherein the toner is a non-magnetic one-component toner.   26. The image forming apparatus according to claim 22, wherein the electrostatic latent image is a digital latent image.   27. The image forming apparatus according to claim 22, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relation of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a negative charge polarity different from the positive charge polarity in the developing device of the toner. The image forming apparatus according to any one of claims 22 to 27.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more external additives At least a toner carrier for carrying a positively charged toner having a positive charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region to form a toner image; An image forming apparatus characterized in that the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in order of the toner base particles, the external additive, and the surface layer of the image carrier from the plus side. .   30. The image forming apparatus according to claim 29, wherein the surface layer of the image carrier is a charge transport layer.   30. The image forming apparatus according to claim 29, wherein a surface layer of the image carrier is a protective layer.   32. The image forming apparatus according to claim 29, wherein the toner is a non-magnetic one-component toner.   The image forming apparatus according to any one of claims 29 to 32, wherein the electrostatic latent image is a digital latent image.   34. The image forming apparatus according to claim 29, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relation of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a negative charge polarity different from the positive charge polarity in the developing device of the toner. The image forming apparatus according to any one of claims 29 to 34.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, toner base particles, and one or more external additives At least a toner carrier for carrying a positively charged toner having a positive charge and transporting the toner to the image carrier, and forming the development region by contacting the toner carrier with the image carrier. An image forming apparatus comprising: a developing device that visualizes the electrostatic latent image by electrically adhering the toner to the electrostatic latent image on the image carrier in a region to form a toner image; The image forming apparatus characterized in that the relationship between the surface layer of the image carrier, the toner base particles and the triboelectric charge train of the external additive is in order of the toner base particles, the surface layer of the image carrier, and the external additive from the plus side. .   37. The image forming apparatus according to claim 36, wherein a surface layer of the image carrier is a charge transport layer.   37. The image forming apparatus according to claim 36, wherein a surface layer of the image carrier is a protective layer.   The image forming apparatus according to any one of claims 36 to 38, wherein the toner is a non-magnetic one-component toner.   40. The image forming apparatus according to claim 36, wherein the electrostatic latent image is a digital latent image.   41. The image forming apparatus according to claim 36, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relation of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a negative charge polarity different from the positive charge polarity in the developing device of the toner. The image forming apparatus according to any one of claims 36 to 41.   The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably mounted on an image forming apparatus main body for forming a fixed image, and includes an image carrier that carries an electrostatic latent image, toner mother particles, and one or more external additives. At least a toner carrier for carrying a charged polarity toner and transporting it to the image carrier, and forming a development area by contacting the toner carrier to the image carrier, A developing device that visualizes the electrostatic latent image by electrically attaching toner to the electrostatic latent image on the image carrier to form a toner image; and (a) for charging the image carrier Charging means, ( (A) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; (c) a transfer unit that transfers the toner image formed by the developing device to a transfer material; d) selected from the group consisting of cleaning means for removing toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in the order of the external additive, toner base particles, and the surface layer of the image carrier from the minus side. A process cartridge characterized by that.   44. The process cartridge according to claim 43, wherein the surface layer of the image carrier is a charge transport layer.   44. The process cartridge according to claim 43, wherein a surface layer of the image carrier is a protective layer.   The process cartridge according to any one of claims 43 to 45, wherein the toner is a non-magnetic one-component toner.   The process cartridge according to any one of claims 43 to 46, wherein the electrostatic latent image is a digital latent image.   The process cartridge according to any one of claims 43 to 47, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relationship of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a different positive charge polarity with respect to the negative charge polarity in the developing device of the toner. The process cartridge according to any one of claims 43 to 48.   The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably mounted on an image forming apparatus main body for forming a fixed image, and includes an image carrier that carries an electrostatic latent image, toner mother particles, and one or more external additives. At least a toner carrier for carrying a charged polarity toner and transporting it to the image carrier, and forming a development area by contacting the toner carrier to the image carrier, A developing device that visualizes the electrostatic latent image by electrically attaching toner to the electrostatic latent image on the image carrier to form a toner image; and (a) for charging the image carrier Charging means, ( (A) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; (c) a transfer unit that transfers the toner image formed by the developing device to a transfer material; d) selected from the group consisting of cleaning means for removing toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in the order of the toner base particles, the external additive, and the surface layer of the image carrier from the minus side. A process cartridge characterized by that.   51. The process cartridge according to claim 50, wherein the surface layer of the image carrier is a charge transport layer.   51. The process cartridge according to claim 50, wherein a surface layer of the image carrier is a protective layer.   53. The process cartridge according to any one of claims 50 to 52, wherein the toner is a non-magnetic one-component toner.   54. The process cartridge according to claim 50, wherein the electrostatic latent image is a digital latent image.   The process cartridge according to any one of claims 50 to 54, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relationship of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a different positive charge polarity with respect to the negative charge polarity in the developing device of the toner. The process cartridge according to any one of claims 50 to 55. The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably mounted on an image forming apparatus main body for forming a fixed image, and includes an image carrier that carries an electrostatic latent image, toner mother particles, and one or more external additives. At least a toner carrier for carrying a charged polarity toner and transporting it to the image carrier, and forming a development area by contacting the toner carrier to the image carrier, A developing device that visualizes the electrostatic latent image by electrically attaching toner to the electrostatic latent image on the image carrier to form a toner image; and (a) for charging the image carrier Charging means, ( (A) an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; (c) a transfer unit that transfers the toner image formed by the developing device to a transfer material; d) selected from the group consisting of cleaning means for removing toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in the order of the toner base particles, the surface layer of the image carrier, and the external additive from the minus side. A process cartridge characterized by that.   58. The process cartridge according to claim 57, wherein the surface layer of the image carrier is a charge transport layer.   58. The process cartridge according to claim 57, wherein a surface layer of the image carrier is a protective layer.   60. The process cartridge according to any one of claims 57 to 59, wherein the toner is a non-magnetic one-component toner.   61. The process cartridge according to claim 57, wherein the electrostatic latent image is a digital latent image.   The process cartridge according to any one of claims 57 to 61, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relationship of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a different positive charge polarity with respect to the negative charge polarity in the developing device of the toner. The process cartridge according to any one of claims 57 to 62.   The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, and includes an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives. At least a toner carrier for carrying a charged polarity toner and transporting it to the image carrier, and forming a development area by contacting the toner carrier to the image carrier, A developing device that visualizes the electrostatic latent image by electrically attaching toner to the electrostatic latent image on the image carrier to form a toner image; and (a) for charging the image carrier Charging means, (b An exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; (c) a transfer unit that transfers the toner image formed by the developing device to a transfer material; ) Selected from the group consisting of cleaning means for removing toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. The relationship between the surface layer of the image carrier, the toner base particles and the external charge additive is in the order of the external additive, toner base particles, and the surface layer of the image carrier from the plus side. Process cartridge characterized by.   The process cartridge according to claim 64, wherein the surface layer of the image carrier is a charge transport layer.   The process cartridge according to claim 64, wherein a surface layer of the image carrier is a protective layer.   The process cartridge according to any one of claims 64 to 66, wherein the toner is a non-magnetic one-component toner.   The process cartridge according to any one of claims 64 to 67, wherein the electrostatic latent image is a digital latent image.   69. The process cartridge according to claim 64, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relation of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a negative charge polarity different from the positive charge polarity in the developing device of the toner. The process cartridge according to any one of claims 64 to 69.   The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, and includes an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives. At least a toner carrier for carrying a charged polarity toner and transporting it to the image carrier, and forming a development area by contacting the toner carrier to the image carrier, A developing device that visualizes the electrostatic latent image by electrically attaching toner to the electrostatic latent image on the image carrier to form a toner image; and (a) for charging the image carrier Charging means, (b An exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; (c) a transfer unit that transfers the toner image formed by the developing device to a transfer material; ) Selected from the group consisting of cleaning means for removing toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. The relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is in the order of the toner base particles, the external additive, and the surface layer of the image carrier from the plus side. Process cartridge characterized by.   72. The process cartridge according to claim 71, wherein the surface layer of the image carrier is a charge transport layer.   72. The process cartridge according to claim 71, wherein a surface layer of the image carrier is a protective layer.   The process cartridge according to any one of claims 71 to 73, wherein the toner is a non-magnetic one-component toner.   The process cartridge according to any one of claims 71 to 74, wherein the electrostatic latent image is a digital latent image.   The process cartridge according to any one of claims 71 to 75, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relation of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a negative charge polarity different from the positive charge polarity in the developing device of the toner. The process cartridge according to any one of claims 71 to 76. The electrostatic latent image formed on the image carrier is developed with toner to form a toner image, and the toner image is transferred to a transfer material with or without an intermediate transfer member, and then fixed. A process cartridge that is detachably attached to an image forming apparatus main body for forming a fixed image, and includes an image carrier that carries an electrostatic latent image, toner base particles, and one or more external additives. At least a toner carrier for carrying a charged polarity toner and transporting it to the image carrier, and forming a development area by contacting the toner carrier to the image carrier, A developing device that visualizes the electrostatic latent image by electrically attaching toner to the electrostatic latent image on the image carrier to form a toner image; and (a) for charging the image carrier Charging means, (b An exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier; (c) a transfer unit that transfers the toner image formed by the developing device to a transfer material; ) Selected from the group consisting of cleaning means for removing toner remaining on the image carrier after the toner image is transferred to the transfer material, and is supported integrally with the image carrier and the developing device. The relationship between the surface layer of the image carrier, the toner base particles and the external additive is in the order of the toner base particles, the surface layer of the image carrier, and the external additive from the plus side. Process cartridge characterized by.   The process cartridge according to claim 78, wherein a surface layer of the image carrier is a charge transport layer.   The process cartridge according to claim 78, wherein a surface layer of the image carrier is a protective layer.   The process cartridge according to any one of claims 78 to 80, wherein the toner is a non-magnetic one-component toner.   The process cartridge according to any one of claims 78 to 81, wherein the electrostatic latent image is a digital latent image.   The process cartridge according to any one of claims 78 to 82, wherein the electrostatic latent image is a digital latent image having an area gradation.   In the relation of the triboelectric charge train between the toner and the surface layer of the image carrier, the surface layer of the image carrier has a negative charge polarity different from the positive charge polarity in the developing device of the toner. The process cartridge according to any one of claims 78 to 83.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner that is carried to the image carrier. At least a toner carrier for forming a developing region by contacting the toner carrier with the image carrier, and in the developing region, the toner is electrically converted into an electrostatic latent image on the image carrier. And a toner used in an image forming apparatus including a developing device that forms a toner image by visualizing the electrostatic latent image by attaching the toner to the toner base particles and at least one type of external toner. A negatively chargeable toner having an additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is from the negative side of the external additive, toner base particles, and image carrier. Toner characterized by surface order   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner that is carried to the image carrier. At least a toner carrier for forming a developing region by contacting the toner carrier with the image carrier, and in the developing region, the toner is electrically converted into an electrostatic latent image on the image carrier. And a toner used in an image forming apparatus including a developing device that forms a toner image by visualizing the electrostatic latent image by attaching the toner to the toner base particles and at least one type of external toner. A negatively chargeable toner having an additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive has the relationship between the toner base particles, the external additive, and the image carrier from the negative side. Toner characterized by surface order   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner that is carried to the image carrier. At least a toner carrier for forming a developing region by contacting the toner carrier with the image carrier, and in the developing region, the toner is electrically converted into an electrostatic latent image on the image carrier. And a toner used in an image forming apparatus including a developing device that forms a toner image by visualizing the electrostatic latent image by attaching the toner to the toner base particles and at least one type of external toner. A negatively chargeable toner having an additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive has a relationship from the negative side to the toner base particles, the surface layer of the image carrier, and the external additive. Toner characterized by the order of agents   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner that is carried to the image carrier. At least a toner carrier for forming a developing region by contacting the toner carrier with the image carrier, and in the developing region, the toner is electrically converted into an electrostatic latent image on the image carrier. And a developing device for visualizing the electrostatic latent image by forming a toner image to form a toner image, the toner used in the image forming device, wherein the toner comprises toner mother particles and at least one external toner. A positively chargeable toner having an additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is such that the external additive, toner base particles, and image carrier A toner having a surface layer order.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner that is carried to the image carrier. At least a toner carrier for forming a developing region by contacting the toner carrier with the image carrier, and in the developing region, the toner is electrically converted into an electrostatic latent image on the image carrier. And a toner used in an image forming apparatus including a developing device that forms a toner image by visualizing the electrostatic latent image by attaching the toner to the toner base particles and at least one type of external toner. A positively chargeable toner having an additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive is such that the toner base particles, the external additive, and the image carrier from the positive side. A toner having a surface layer order.   An image carrier that carries an electrostatic latent image, an exposure device that forms the electrostatic latent image on the image carrier by exposing the image carrier, and a toner that is carried to the image carrier. At least a toner carrier for forming a developing region by contacting the toner carrier with the image carrier, and in the developing region, the toner is electrically converted into an electrostatic latent image on the image carrier. And a toner used in an image forming apparatus including a developing device that forms a toner image by visualizing the electrostatic latent image by attaching the toner to the toner base particles and at least one type of external toner. A positively chargeable toner having an additive, and the relationship between the surface layer of the image carrier, the toner base particles, and the triboelectric charge train of the external additive has a relationship from the positive side to the toner base particles, the surface layer of the image carrier, and the external additive. A toner characterized by the order of agents.   The toner according to any one of claims 85 to 90, which is a non-magnetic one-component toner.

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