JP2006184370A - Image forming apparatus, process cartridge, and toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing faulty charge and occurrence of image defects due to burying of conductive fine particles in a toner surface or toner fusion to conductive fine particles, and faulty charge and occurrence of image defects due to burying of conductive fine particles in a photoreceptor surface. <P>SOLUTION: The image forming apparatus in which an image carrier surface is charged by a charging member by way of conductive fine particles uses a toner obtained by externally adding at least conductive fine particles to toner base particles, wherein the toner base particles have a coefficient of kinetic friction in a range of 0.15-0.50, the toner contains 2-15 wt.% of a THF-soluble component whose molecular weight is <1,000 by GPC, with respect to a glass transition temperature Tg of the toner, the ratio (G'1/G'2) between a storage elasticity G'1 of the toner at Tg-5°C and a storage elasticity G'2 of the toner at Tg+5°C is in a range of 1-30, and the storage elasticity G'2 at Tg+5°C is in a range of 6×10<SP>6</SP>-1×10<SP>8</SP>(Pa). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an image forming apparatus that forms an electrostatic latent image with toner of colored fine particles by an electrostatic copying process such as a copying machine, a facsimile machine, and a printer, and a toner and a process cartridge used therefor.

In Patent Document 1, which is a combination of conductive fine particles for charge injection charging, a specific toner molecular weight, and a dynamic friction coefficient, the charging device for the image carrier is a nonmagnetic charging method using nonmagnetic conductive particles. Accordingly, it is disclosed that a decrease in image density and an increase in fog can be prevented, and the charge accelerating particles can be stably supplied to the nip between the charging member and the image carrier.
However, there is no disclosure about deterioration of chargeability controllability caused by fusing and embedding conductive fine particles on the toner surface.

In the prior art, the invention of Patent Document 2 is the closest to the present invention. Patent Document 2 is a combination with rheological properties, but in the specification, only the rheological properties have an effect on fixing properties, and there is no description about the relevance of embedding with conductive fine particles.
Patent Document 3 discloses a developer having conductive particles and insulating particles, which suppresses latent image blur due to adhesion of fine conductive particles. In addition, there is no description about deterioration of chargeability controllability due to fusion and embedding of conductive fine particles on the toner surface.
Further, Patent Document 4 also defines the charge injection method, toner particle size, shape, and wax dispersion diameter in the toner, thereby obtaining high resolution image quality and suppressing the fusion of conductive fine particles to the toner. However, since there is no regulation on the toner surface, the effect of suppressing the embedding of additives on the surface is insufficient.

JP 2002-207346 A JP 2003-021947 A Japanese Patent Laid-Open No. 2004-070291 Japanese Patent Application No. 2004-264920

The present invention has been made in view of the above-described problems, and the charging failure, image defect, and conductive fine particles are exposed to conductive fine particles embedded in the toner surface or the toner is spent (fused) on the conductive fine particles. It is an object of the present invention to provide an image forming apparatus capable of preventing charging failure and image failure caused by being embedded in the body surface.

As means for solving the above problems, the present invention has the following features.
The image forming apparatus according to claim 1, an image carrier that carries a latent image, a charging device that charges the surface of the image carrier, an exposure device that forms a latent image on the surface of the charged image carrier, and an image carrier And a developing device that develops the latent image on the body with toner on a developing roller. The charging device charges the surface of the image carrier with a charging member having conductive fine particles interposed therebetween, and the toner Is obtained by externally adding at least conductive fine particles to toner base particles, and the dynamic friction coefficient of the toner base particles is in the range of 0.15 to 0.50.
The image forming apparatus according to claim 2, wherein the toner further contains 2 to 15 wt% of a component having a molecular weight of less than 1000 THF-soluble components by GPC.
4. The image forming apparatus according to claim 3, further comprising: a storage elastic modulus G′1 at Tg−5 ° C. and a storage elastic modulus G′2 at Tg + 5 ° C. with respect to the glass transition point Tg of the toner. The ratio (G′1 / G′2) is in the range of 1 to 30, and the storage elastic modulus G′2 at Tg + 5 ° C. is in the range of 6 × 10 ⁶ to 1 × 10 ⁸ (Pa). Features.
The image forming apparatus according to claim 4, further comprising a transfer device that transfers the visualized toner image on the image carrier to a recording medium, and a transfer residue on the image carrier. The toner is collected by a developing device.

The image forming apparatus according to claim 5, further comprising a plurality of developing devices.
The image forming apparatus according to claim 6 is characterized in that the peripheral speed of the developing roller is 240 mm / sec or more.
The image forming apparatus according to claim 7, wherein the toner further contains a release agent.
The image forming apparatus according to claim 8, wherein the toner has a shape factor SF-1 in a range of 100 to 180.
The image forming apparatus according to claim 9, wherein the toner further includes a magnetic material.
The image forming apparatus according to claim 10 is characterized in that the image forming apparatus further uses a mixture of toner and a magnetic carrier coated with a resin.

A process cartridge according to an eleventh aspect is a process cartridge used in the image forming apparatus according to any one of the first to tenth aspects, wherein the process cartridge includes an image carrier that carries an electrostatic latent image; At least a developing device disposed opposite to an image carrier that carries an electrostatic latent image is integrally supported and is detachable from the image forming apparatus main body.
The toner according to claim 12, an image carrier that carries a latent image, a charging device that charges the surface of the image carrier, an exposure device that forms a latent image on the surface of the charged image carrier, and an image carrier A developing device that develops the latent image of the image with the toner on the developing roller, and the charging device is a toner used in an image forming apparatus that charges the surface of the image carrier with a charging member having conductive fine particles interposed therebetween. The coefficient is in the range of 0.15 to 0.50.
In the toner according to claim 13, the toner further includes 2 to 15 wt% of a component having a molecular weight of less than 1000 in a THF soluble component by GPC.
15. The toner according to claim 14, further comprising a ratio of a storage elastic modulus G′1 at Tg−5 ° C. and a storage elastic modulus G′2 at Tg + 5 ° C. with respect to the glass transition point Tg of the toner ( G′1 / G′2) is in the range of 1 to 30, and the storage elastic modulus G′2 at Tg + 5 ° C. is in the range of 6 × 10 ⁶ to 1 × 10 ⁸ (Pa). To do.

The toner according to claim 15, further comprising: a transfer device that transfers a visible toner image on the image carrier to a recording medium, wherein the transfer residual toner on the image carrier is removed. It collect | recovers with a developing device, It is characterized by the above-mentioned.
In the toner according to claim 16, the image forming apparatus is further characterized in that a peripheral speed of the developing roller is 240 mm / sec or more.
The toner according to claim 17 is characterized in that the toner further contains a release agent.
The toner according to claim 18 is further characterized in that the toner has a shape factor SF-1 in the range of 100 to 180.
The toner according to claim 19 is characterized in that the toner further contains a magnetic substance.
The toner according to claim 20 is further characterized in that the toner is used by mixing the toner and a magnetic carrier coated with a resin.
The toner according to claim 21, further comprising: an image carrier that carries an electrostatic latent image; and a developing device that is disposed to face at least the image carrier that carries an electrostatic latent image. And a process cartridge that can be attached to and detached from the image forming apparatus main body.

As described above, according to the means for solving the above, in the image forming apparatus of the present invention, the additive containing the softening component is specified by containing 3 to 15% of the component having a weight average molecular weight of less than 1000 in the toner. In addition to preventing embedding, it is possible to improve the dispersibility of wax by containing a specific amount, and to suppress embedding of fine particles.
Further, in the toner of the present invention, the coefficient of dynamic friction is 0.15 to 0.35, so that the wax dispersibility can be improved and the fusion of the fine particles can be suppressed, whereby the conductive fine particles are embedded in the toner surface over time. , It is possible to prevent fusing and to obtain a development system that is stable over a long period of time.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

In the charge injection method, the specific toner molecular weight and the dynamic friction coefficient can suppress the embedding of conductive fine particles on the surface and provide a stable development method over a long period of time.
In the image forming apparatus of the present invention, it is desirable that the toner is obtained by externally adding at least conductive fine particles to toner base particles, and the dynamic friction coefficient of the toner base particles is in the range of 0.15 to 0.50.

(1) Reason why the range of 0.15 to 0.50 is good When the dynamic friction coefficient of the toner is less than 0.15, the wax is precipitated on the toner surface due to poor dispersion of the wax, and conductive fine particles are embedded in the portion. White spots or solid images due to uneven charging due to charging failure due to toner fusing or toner fusing to the photoconductor, or charging failure due to wax fusing to conductive fine particles. Non-uniformity occurs. Further, as a developer, the toner cohesiveness is deteriorated, or the fusing to the carrier is caused, so that the developing ability is deteriorated, and a problem in image quality such as a reduction in image density is caused.
Also, when the dynamic friction coefficient exceeds 0.5, image streaks due to scraping of the photoreceptor surface due to a large frictional force, image density reduction or glossiness due to embedding of conductive fine particles on the photoreceptor surface. Nonuniformity in image quality such as non-uniformity of a solid image occurs.

(2) Measuring method The dynamic friction coefficient of the toner surface is measured using a fully automatic frictional wear analyzer manufactured by Kyowa Interface Science Co., Ltd. obtained by applying a load of 6 t / cm ² to a toner having a mass of 3 g to form a disk-shaped pellet having a diameter of 40 mm. To do. At this time, a point contact of a 3 mm stainless sphere is used as the contact.

(3) A method for obtaining a toner having a dynamic friction coefficient in the above range. For example, when the ratio of the release agent present on the toner surface is adjusted, or when the release agent is uniformly dispersed with a small particle diameter, The ratio of the amount of release agent present in is equal to the amount of release agent contained. However, when it exists in a large particle size, the ratio of the release agent amount present on the toner surface is larger than the included release agent amount.

In the case of a pulverizing system, when the kneaded toner is pulverized and atomized, it is often pulverized by an external force such as a mechanical impact or an impact caused by a jet stream. Occur. Since this is a release agent, when the release agent exists in a large particle size, the amount of the release agent on the toner surface increases. The dispersion state of the release agent is greatly influenced by the share of kneading. The larger the kneading torque, the better the dispersion and the higher the coefficient of friction. The dispersion state in the toner also depends on the particle size distribution of the release agent used. Will change greatly. The particle size distribution in the raw material of the release agent is 30 to 300 μm, preferably 30 to 200 μm, and more preferably 30 to 100 μm. The smaller the particle size distribution in the raw material of the release agent, the better the dispersion in the toner. Therefore, even if a large amount is added as a prescription, the target friction coefficient range can be obtained.

The difference between the acid value of the release agent and at least one resin in the toner is within 10, preferably within 8, and more preferably within the range of 0 to 5, so that the binder resin and the release agent Dispersibility is improved. By containing a resin having a crosslinking component as the resin, torque during kneading is obtained, the release agent is well dispersed, and the friction coefficient is increased. The amount of the crosslinking component is 5 to 40% by weight, preferably 10 to 30% by weight, and the toner formulation is aimed at containing 10 to 80% by weight, preferably 20 to 70% by weight of the resin containing the crosslinking component. The coefficient of friction can be obtained.

In the case of a polymerization system, the ratio of the release agent amount present on the toner surface is adjusted by the stirring speed, the temperature, the amount of the surfactant, and the like when dispersed in the solvent. For example, when adjusting with the dispersibility of an organic pigment, dispersibility can be controlled by a process condition such as making a pigment into a master batch with a resin in advance. As in the case of the release agent, when the pigment dispersion state has a large particle diameter, the amount of pigment on the toner surface increases and the friction coefficient increases. Depending on the selection of such raw materials and the toner manufacturing method, the dynamic friction coefficient of the toner can be in the range of 0.15 to 0.50. The preferred range is 0.25 to 0.35.

The toner of the present invention is characterized by containing 2 to 15 wt% of a component having a molecular weight of less than 1000 as a THF soluble component by GPC.
(1) Reason that the range containing 2 to 15 wt% of the component having a molecular weight of less than 1000 is good. If it is less than 2 wt%, the difference in the molecular weight between the binder resin and the wax becomes large, and the wax dispersibility deteriorates.
If it is 15 wt% or more, the toner spent and conductive fine particles are buried due to the large amount of low molecular weight components.

(2) Measuring method The molecular weight by GPC is measured by stabilizing the column in a heat chamber at 40 ° C., and flowing THF as a solvent at a flow rate of 1 ml / min. Measure by injecting 50 to 200 μl of a THF sample solution of the resin prepared to 6% by weight.
In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, PRESuReChemical Co. Alternatively, the molecular weights manufactured by Toyo Soda Industry Co., Ltd. are 6 × 102, 2.1 × 103, 4 × 103, 1.75 × 104, 5.1 × 104, 1.1 × 105, 3.9 × 105, 8.6. It is appropriate to use those of × 105, 2 × 106, 4.48 × 106, and at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

In the toner of the present invention, the ratio (G′1 / G′2) of the storage elastic modulus G′1 at Tg−5 ° C. and the storage elastic modulus G′2 at Tg + 5 ° C. with respect to the glass transition point Tg of the toner. The storage elastic modulus G′2 at Tg + 5 ° C. is in the range of 6 × 10 ⁶ to 1 × 10 ⁸ (Pa).
(1) The reason why the above range is good G′1 and G′2 are processes in which the toner in the glass state or the glass transition start state transitions to a state where the toner can be deformed by an external force. There is no occurrence of embedded fine particles. When (G′1 / G′2) exceeds 30, deformation is large and embedding of conductive fine particles is likely to occur. If the storage elastic modulus G′2 at Tg + 5 ° C. is less than 6 × 10 ⁶ (Pa), sufficient rubber elasticity cannot be obtained, and embedding of conductive fine particles tends to occur. When it exceeds 1 × 10 ⁸ (Pa), the toner scrapes the surface of the photoreceptor.

(2) Method for measuring storage elastic modulus About 1 g of toner is pressure-molded to prepare a measurement sample having a diameter of 25 mm and a thickness of 2 mm.
The rheological characteristics are measured using a dynamic analyzer RDA II (manufactured by Rheometric) using a parallel plate with a diameter of 25 mm, applying sinusoidal vibration and sweeping the temperature. The measurement frequency is 1 Hz, the initial value of strain is 10%, and the measurement is performed at intervals of 5 ° C. from 40 ° C. to 200 ° C.

(3) Measuring method of glass transition point Tg of toner DSC measuring apparatus: Measured according to ASTM D3418-82 using a differential scanning calorimeter DSC-7 (manufactured by Perkin Elmer). The measurement sample is weighed 5 to 25 mg, preferably 10 mg. Put this in an aluminum pan, cover it and set it on the sample stage. As a reference, 10 mg of aluminum oxide was weighed and set on an aluminum pan, and once heated to a measurement temperature of 30 to 200 ° C. at a heating rate of 10 ° C./min, cooled at a cooling rate of 10 ° C./min, and again 30 to 200 The temperature is raised to 10 ° C. at a heating rate of 10 ° C./min. The intersection of the base line before and after the endothermic peak due to the second temperature increase and the differential heat curve is defined as the glass transition point Tg of the toner.

(4) Method for obtaining toner in the above range The binder resin contains 5 to 40% of a THF-insoluble component, and this is molecularly cut by kneading mechanical shearing to obtain a branched polymer. Even if it exceeds, storage elastic modulus G 'will not fall rapidly, but the target characteristic can be acquired.
In the 52nd column and below, details of examples and comparative examples of the toner of the present invention will be described.

Here, the image forming apparatus of the present invention will be described.
FIG. 1 is a schematic diagram showing the configuration of an embodiment of an image forming apparatus according to the present invention. In the figure, reference numeral 100 is a copying apparatus main body, 200 is a paper feed table on which the copying apparatus is placed, 300 is a scanner mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (ADF) mounted thereon.
The copying apparatus main body 100 has a tandem type in which four image forming units 18 each having various units for performing an electrophotographic process such as charging, developing, and cleaning are arranged in parallel around a photosensitive member 40 as a latent image carrier. An image forming apparatus 20 is provided. Above the tandem image forming apparatus 20, there is provided an exposure apparatus 21 that exposes the photoreceptor 40 with laser light based on image information to form a latent image. Further, an intermediate transfer belt 10 made of an endless belt member is provided at a position facing each photoconductor 40 of the tandem type image forming apparatus 20. A primary transfer unit 62 for transferring the toner images of the respective colors formed on the photoconductor 40 to the intermediate transfer belt 10 is disposed at a position facing the photoconductor 40 via the intermediate transfer belt 10.

A secondary transfer device 22 that collectively transfers the toner images superimposed on the intermediate transfer belt 10 onto the recording paper conveyed from the paper feed table 200 is disposed below the intermediate transfer belt 10. The secondary transfer device 22 is configured by spanning a secondary transfer belt 24 that is an endless belt between two rollers 23, and is disposed by pressing against the support roller 16 via the intermediate transfer belt 10. The toner image on 10 is transferred to a recording sheet. A fixing device 25 for fixing the image on the recording paper is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 252 against a fixing belt 254 which is an endless belt.
The secondary transfer device 22 described above also has a sheet transport function for transporting the recording paper after image transfer to the fixing device 25. Of course, a transfer roller or a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to provide this sheet conveyance function together.
In FIG. 1, a reversing device 28 for reversing the recording paper so as to record images on both sides of the recording paper is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above. .

The developing device 4 of the image forming unit 18 uses a developer containing the above toner. In the developing device 4, the developer carrying member carries and conveys the developer, and an alternating electric field is applied at a position facing the photoconductor 40 to develop the latent image on the photoconductor 40. By applying the alternating electric field, the developer is activated, the charge amount distribution of the toner can be narrowed, and the developability can be improved.
In addition, a process cartridge that is integrally supported together with the photosensitive member 40 and the developing device and is detachably formed on the image forming apparatus main body can be obtained. In addition, the process cartridge may include a charging unit.

  FIG. 2 is a schematic diagram showing the configuration of a charging device used in the image forming apparatus of the present invention. The charging device 14 includes a charging roller 14a as a charging member disposed opposite to the photoconductor 40, and a charging cleaning member 14b disposed so that the charging roller 14a contacts a surface opposite to the surface facing the photoconductor 40. It consists of. Further, the charging roller 14a includes pressure springs 19 and 19 which are urging members that urge both ends of the charging roller 14a toward the photoreceptor 40 side. The charging roller 14a is disposed so that the charging roller 14a and the photosensitive member have a nip portion by contacting the photosensitive member 40 and contacting the photosensitive member 40 with a predetermined pressing force. Further, a minute gap may be provided between the charging roller 14 a and the photoconductor 40 as long as the conductive fine particles supplied from the developer are interposed between the charging roller 14 a and the photoconductor 40. Such a small gap is set by, for example, winding a spacer member having a certain thickness around the non-image forming regions at both ends of the charging roller 14a so that the surface of the spacer member abuts on the surface of the photoreceptor 40. be able to.

In addition, the image forming apparatus includes a transfer device that transfers the visible toner image on the photoconductor 40 to a recording medium, and the transfer residual toner on the photoconductor 40 is collected by a developing device.
The transfer device may be any one of a corona transfer system that applies a direct current and / or an alternating electric field, a roller transfer system, a roller transfer system using heat and / or pressure, and a belt transfer system. With this transfer device, most of the toner on the photoreceptor 40 is transferred to a recording medium such as transfer paper or an OHP sheet. However, a part of the toner remains on the photoreceptor 40 without being transferred.

The residual toner is not cleaned by the cleaning device but is transported as it is and collected by the magnetic brush of the developing device shown in FIG. Thus, by not providing the cleaning device, the design around the photoconductor 40 becomes easy, and the image forming apparatus can be downsized. Further, since a large amount of conductive fine particles remaining on the photoconductor 40 can be supplied to the charging roller 14a by not providing a cleaning device, the conductive fine particles on the charging roller 14a increase, and the photoconductor 40 is uniformly charged. Is possible. In addition, the toner shape factor SF-1 is set to 100 to 180, and a spherical shape is used to increase the transfer rate, thereby reducing the amount of remaining toner and removing the cleaning device.

As shown in FIG. 1, the image forming apparatus of the present invention is provided with a plurality of developing devices for each color developer.
In the image forming apparatus of the present invention, the peripheral speed of the developing roller is 240 mm / sec or more. By using the toner of the present invention, it is possible to prevent the fusion and embedding of conductive fine particles on the toner surface and to perform the above high-speed image processing stably over a long period of time.

FIG. 3 is a cross-sectional view of a charging roller used in the image forming apparatus of the present invention. The charging roller 14 a includes a cored bar 141 as a cylindrical conductive support, and an elastic / medium resistance layer 142 formed on the outer peripheral surface of the cored bar 141 with a uniform thickness.
The charging roller 14a is connected to a power source (not shown) and is applied with a predetermined voltage. The voltage may be only a direct current (DC) voltage or a voltage obtained by superimposing an alternating current (AC) voltage on a DC voltage. At this time, the conductive fine particles are interposed between the charging roller 14 a and the photoreceptor 40.

  The charging roller 14a will be described. As shown in FIG. 3, the elastic / medium resistance layer 142 is formed by providing a resin composition on the peripheral surface of the core metal 141 by extrusion molding or injection molding. Further, in order to prevent the elastic / medium resistance layer 142 from being deformed over time and changing the gap between the photoreceptor 40 and the charging roller 14a, the elastic / medium resistance layer 142 having elasticity and low electric resistance is provided. Have. The thermoplastic resin used for the elastic / medium resistance layer 142 is not particularly limited as long as it can maintain elasticity, but polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS). It is preferable to use general-purpose resins such as urethane and silicone, and these foams because the molding process is easy.

The elastic / medium resistance layer 142 is formed of a thermoplastic resin composition in which a metal oxide such as carbon black, zinc oxide, titanium oxide, and tin oxide, and a polymer type ion conductive agent are dispersed. Here, the charging roller 14a which is a contact charging member forms a nip region with the photoreceptor 40 as an electrode. At the same time as obtaining sufficient contact with the photoreceptor 40 by providing elasticity, the moving photoreceptor 40 is charged. The resistance value of the elastic / medium resistance layer 142 is preferably in the range of 10 ⁴ to 10 ⁷ Ω. When the resistance value exceeds 10 ⁷ Ω, the amount of charge is insufficient, and the photosensitive member 40 cannot obtain a sufficient charging potential to obtain an image without unevenness. On the other hand, if the resistance value is less than 10 ⁴ Ω, leakage to the entire photoreceptor 40 occurs.

  Further, a contact state with uniform and low hardness is preferable from the mechanical stress on the toner at the contact portion. Specifically, the Asker C hardness is preferably 15 to 50 degrees, and more preferably 20 to 40 degrees. A contact state can be configured. The surface of the charging roller 14a is preferably provided with irregularities that can hold the conductive fine particles. If the hardness of the charging roller 14a is too low, the shape is not stable, so that the contact property with the member to be charged is deteriorated. If the hardness is too high, not only the nip portion cannot be secured between the photosensitive member 40 but also the photosensitive roller 14a. The contact with the body 40 may be deteriorated and the photoreceptor 40 may be damaged. Further, it is preferable to use an elastic member for the charging roller 14a and press the photosensitive member 40 with a constant pressure. Thereby, the nip region can be widened.

  Further, the charging roller 14a is rotatably supported by bearing members (not shown) at both ends of the charging roller 14a and arranged substantially in parallel with the photosensitive member 40, and the bearing members on both sides are pressed against the photosensitive member 40 by an elastic member. Thus, the photosensitive member 40 is brought into pressure contact. A nip region having a predetermined width is formed. The charging roller 14a is driven to rotate so as to move in the opposite direction to the photoconductor 40 at the same peripheral speed. Here, the charging roller 14 a may be driven by the photoreceptor 40. Further, the charging roller 14a may be rotationally driven to have a speed difference from the photoreceptor 40. This can be appropriately determined from the peripheral speed of the photoreceptor 40, the peripheral speed of the developing sleeve, and the like.

At this time, in this embodiment, the toner has a weight average particle diameter of 2 to 8 μm, a shape factor SF-1 of 100 to 180, and a number average particle diameter of the release agent dispersed in the toner of 0.1 to 0.1. In the range of 1.0 μm, at least conductive fine particles are externally added.
The smaller the toner particle size, the better the reproducibility of fine lines and fine dots. As a result, particularly when used in a full color image forming apparatus, excellent glossiness of the image can be obtained. It is said that the smaller the toner particle size, the more advantageous it is to obtain a high-resolution and high-quality image, but it is disadvantageous for transferability and cleaning property. When the weight average particle diameter of the toner is in the range of 2 to 8 μm, it is possible to achieve both high resolution images and cleaning properties. Further, since the release agent contained and dispersed in the toner is easily exposed to the surface when subjected to heat and / or pressure, the occurrence of hot offset of fixing can be suppressed. Further, the smaller the surface area per unit weight, the more conductive fine particles can be externally added to the toner surface.

In addition, when the weight average particle size is smaller than the above range, in the two-component developer, the toner is fused to the surface of the magnetic carrier in the developing device for a long period of time, and the charging ability of the magnetic carrier is lowered. When used as a developer, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur. Conversely, when the toner weight average particle diameter is larger than the above range, it becomes difficult to obtain a high-resolution and high-quality image, and the balance of the toner in the developer is performed. In many cases, the variation in the particle size of the toner becomes large. In particular, when it is in the range of 2 to 6 μm, it is preferable because a high-resolution image can be obtained.
In addition, when the ratio Dv / Dn of the weight average particle diameter to the number average particle diameter exceeds 1.40, the charge amount distribution becomes wide and the resolution is lowered, which is not preferable. The average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II and a Coulter Multisizer II (both manufactured by Coulter). In the present invention, an interface (manufactured by Nikka Giken) that outputs a number distribution and particle size distribution using a counter-counter TA-II type (using a 50 μm aperture as the aperture) and a PC9801 personal computer -It was connected to (manufactured by NEC) and measured.

The toner has a shape factor SF-1 in the range of 100 to 180. FIG. 4 is a diagram schematically showing the shape of the toner for explaining the shape factor SF-1.
The shape factor SF-1 indicates the ratio of the roundness of the toner shape, and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
If the toner shape factor SF-1 is a value close to 100, the shape of the toner is close to a sphere, and the contact between the toner and the toner, or the contact between the toner and the photoreceptor 40 becomes a point contact. Becomes weaker, the fluidity becomes higher, and the adhesion between the toner and the photoreceptor 40 becomes weaker, and the transfer rate becomes higher. Furthermore, since the adhesion force with the conductive fine particles on the toner surface is reduced, in particular, since the conductive fine particles are not charged because it is conductive, no electrostatic adhesion force acts between the toner and the toner. It is easy to move from the toner surface to the charging roller 14a. On the other hand, if the value of the shape factor SF-1 is greater than 180, the shape factor SF-1 becomes indefinite, which is not preferable because developability and transferability deteriorate.

  In this embodiment, the number average particle size of the release agent dispersed in the toner is in the range of 0.1 to 1.0 μm. By being in this range, even if the toner particles are broken, the conductive fine particles are not contaminated, and the function of the conductive fine particles as the charge promoting particles for direct injection charging is not hindered. Further, when the dispersion diameter of the release agent is within this range, it is considered that the adhesive force between the conductive fine particles and the toner becomes appropriate, and the developer is not liberated from the toner surface in a large amount, and The charging roller 14a creates a state of being easily transferred, and the function of the conductive fine particles as the charge accelerating particles is more effectively and stably exhibited. Furthermore, since the release agent in the toner is easily exposed to the surface when subjected to heat and / or pressure, occurrence of hot offset in fixing can be suppressed. The release agent is preferably near the toner surface and not exposed. This is easily exposed to the surface by heat or the like, but if it is exposed to the surface in a normal state, it adheres to the carrier or the like, thereby inhibiting the chargeability of the carrier. However, when the number average particle diameter of the release agent dispersed is in the range of 0.1 to 1.0 μm, it is possible to improve the releasability of fixing and to suppress the decrease in chargeability of the carrier. . In particular, when the weight average particle diameter of the toner is in the range of 2 to 8 μm, the exposed area ratio on the toner surface can be lowered. When the number average particle size of the release agent is less than 0.1 μm, the occurrence of hot offset in fixing cannot be suppressed, and when the number average particle size of the release agent exceeds 1.0 μm, the chargeability of the carrier is lowered. .

Furthermore, in the toner used in the image forming apparatus of the present invention, at least conductive fine particles are externally added. The conductive fine particles are collected by the charging roller 14a and carried on the surface of the charging roller 14a through the gap between the charging roller 14a and the photoreceptor 40, and come into contact with the opposing photoreceptor 40. The charging roller 14a carries conductive fine particles from the beginning. However, the charging roller 14a may be separated from the charging roller 14a by being attracted to the photosensitive member 40 in contact therewith. For this reason, the conductive fine particles on the charging roller 14a may be reduced and the contact with the photoreceptor 40 may be lost or the contact area may be reduced. In this case, since it is difficult to uniformly charge the photoconductor 40, the toner is replenished by externally adding it to the toner. This is because the conductive fine particles externally added to the toner surface are developed together with the toner, but in the transfer area of the electrostatic transfer system, a part of the conductive fine particles that are not transferred and remain are generated. This is part of a cleaning blade of the cleaning device is recovered to the charging roller 14a and slip through, it is supported. When the conductive fine particles on the charging roller 14a increase, the pressing force to the photoconductor 40 becomes stronger and the amount to be separated increases. For this reason, the conductive fine particles on the charging roller 14a can be kept substantially constant.

The conductive fine particles have an electric resistance in the range of 10 ⁰ to 10 ⁸ Ω · cm. If the electrical resistance of the conductive fine particles is low and less than 10 ⁰ Ω · cm, a large current may flow from the charging roller 14 a to the photoconductor 40 and damage the photoconductor 40. If the electric resistance exceeds 10 ⁸ Ω · cm, it is difficult to charge the photoreceptor 40 and it is difficult to obtain uniform charging.
This electric resistance is obtained by providing a cylindrical hole having a diameter of 1 cm ² with an insulating resin, for example, a fluororesin, on a metal electrode, and injecting conductive fine particles so that the height is 1 cm. A 1 kg weight / electrode is placed on the electrode, and a voltage of 100 V is applied to the electrode to measure the electrical resistance.
The number average particle diameter is in the range of 1.0 to 3.0 μm. Since the finer conductive particles can contact the photoreceptor 40 uniformly, the photoreceptor 40 can be charged uniformly. However, when the number average particle size is less than 1.0 μm, the adhesion with the toner becomes strong, and therefore the amount remaining on the photoreceptor 40 at the time of transfer decreases. When a large amount is added to the toner, free conductive fine particles are generated, which makes it difficult to adjust the charge amount of the toner. On the other hand, if the number average particle diameter exceeds 3.0 μm, the contact with the photoreceptor 40 becomes non-uniform, and image unevenness occurs in the halftone part and the solid part.
The number average particle diameter was directly measured by observing the conductive fine particles with SEM, STM or the like.

The toner of the present invention can be mixed with a magnetic carrier and used as a two-component developer. In this case, the carrier to toner content ratio in the developer is preferably 1 to 10 parts by weight of toner with respect to 100 parts by weight of carrier. As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, magnetic resin carrier having a particle diameter of about 20 to 200 μm can be used. Examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene acrylic copolymer resins, Halogenated olefin resins such as vinyl, polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resins, polyethylene resins, polyvinyl fluoride resins, polyvinylidene fluoride resins, polytrifluoroethylene resins, polyhexafluoro Propylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinylidene fluoride and non- Monomers including a fluoro terpolymers such, and silicone resins. Moreover, you may contain electrically conductive powder etc. in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle diameter of 1 μm or less. When the average particle diameter is larger than 1 μm, it becomes difficult to control electric resistance.
The toner of the present invention can also be used as a one-component magnetic toner that does not use a carrier or a non-magnetic toner.

  In addition, when preparing the developer, in order to improve the fluidity, storage stability, developability, and transferability of the developer, the hydrophobic silica fine particles listed above are further listed in the developer produced as described above. Inorganic fine particles such as powder may be added and mixed. For mixing external additives, a general powder mixer is used, but it is preferable to equip a jacket or the like to adjust the internal temperature. In order to change the load history applied to the external additive, the external additive may be added in the middle or gradually. Of course, you may change the rotation speed of a mixer, rolling speed, time, temperature, etc. A strong load may be given first, then a relatively weak load, and vice versa. Examples of the mixing equipment that can be used include a V-type mixer, a rocking mixer, a Ladige mixer, a Nauter mixer, a Henschel mixer, and the like.

In addition to the toner, external additives for adjusting the fluidity and chargeability of the toner are added. As the external additive, inorganic fine particles and organic fine particles can be used. As the inorganic fine particles, metal compounds such as oxides, nitrides, carbides, and carbonates are used. Specific examples of the inorganic fine particles include, for example, silicon oxide (silica), aluminum oxide (alumina), titanium oxide (titania), zinc oxide, zirconium oxide, cerium oxide, tungsten oxide, manganese oxide, and barium titanate and titanium. Examples thereof include oxides such as strontium acid, magnesium titanate, calcium carbonate, and potassium carbonate, silicon nitride, aluminum nitride, and the like, nitrides such as carbon nitride, and carbides such as nitrogen carbide. In particular, oxides of silicon, titanium, and aluminum are preferably used.
In addition, the organic fine particles include polymer fine particles such as vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization. Examples thereof include polymer particles made of resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, and polycarbonate resin.

Such an external additive can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. It is done. The number average particle size of the primary particles before forming the aggregate of the external additive is preferably 5 nm to 500 nm. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight.
Examples of the cleaning property improving agent for removing the developer after transfer remaining on the photoreceptor 40 or the primary transfer medium include fatty acid metal salts such as zinc stearate and calcium stearate, such as polymethyl methacrylate fine particles and polystyrene fine particles. And polymer fine particles produced by soap-free emulsion polymerization. The polymer fine particles preferably have a relatively narrow particle size distribution and a number average particle size of 1 nm to 100 nm.

Moreover, it is preferable that the shape of a mold release agent is a substantially spherical shape. In order to suppress the area ratio exposed on the toner surface and to contain a lot of the release agent in the toner, a true sphere is preferable. In the irregular shape, the area ratio exposed on the toner surface decreases if the toner particles are arranged in parallel toward the inside of the toner. However, if they are arranged at random, the area ratio exposed on the toner surface increases. As a result, the chargeability of the carrier decreases and the transfer rate also decreases.

The operation of the image forming apparatus is as follows.
First, a document is set on the document table 30 of the automatic document feeder 400, or the automatic document feeder 400 is opened and a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed. Hold it down.
When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At that time, the scanner 300 is immediately driven to travel the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34 and reflects by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  When a start switch (not shown) is pressed, one of the support rollers 14, 15, 16 is rotated by a drive motor (not shown), the other two support rollers are driven to rotate, and the intermediate transfer belt 10 is rotated and conveyed. To do. At the same time, the photosensitive member 40 is rotated by the individual image forming means 18, and a DC voltage is applied through the conductive fine particles carried on the charging roller 14 a of the charging device to charge the photosensitive member 40. The charged photoconductor 40 is caused to emit light from a light emitting element of an exposure device in response to a signal from the image forming apparatus main body control unit, and is irradiated with laser light to form an electrostatic latent image. Each latent image formed corresponding to black, yellow, magenta, and cyan is developed by a developing device having black, yellow, magenta, and cyan toners to form a visible image. A monochrome image of black, yellow, magenta, and cyan is formed on each photoreceptor 40. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller 45. Then, the sheets are separated one by one into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped.
Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and is transferred by the secondary transfer device 22. A color image is recorded on the sheet.

The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image, and then the switching roller 55 is used to switch the discharge image. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and the image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
On the other hand, the intermediate transfer belt 10 after the image transfer is removed by the intermediate transfer belt cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after the image transfer, so that the tandem image forming apparatus 20 can prepare for the image formation again.

Hereinafter, details of Examples 1 and 2 and Comparative Examples 1 and 2 of the monochrome two-component toner will be described.
[Example 1]
Polyester resin (glass transition point 63 ° C., containing 30% THF-insoluble matter) 80 parts by weight styrene-nbutyl acrylate copolymer (glass transition point 70 ° C., containing THF-insoluble matter 0%) 20 parts by weight carbon black (Mitsubishi Chemical # 44) 10 parts by weight Carnauba wax (Toa Kasei, sized to 40-250 μm) 7 parts by weight
Metallic azo dye Bontron S-34 (Orient Chemical) 3 parts by weight

[Example 2]
Polyester resin (Glass transition point 67 ° C., containing 40% THF-insoluble matter) 50 parts by weight Polyester resin (Glass transition point 65 ° C., containing THF-insoluble matter 0%) 50 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Part polypropylene (Sanyo Kasei Biscol 550P, average particle size adjusted to 120-280 μm) 2 parts by weight carnauba wax (Toa Kasei, particle size adjusted to 30-100 μm) 4 parts by weight
3 parts by weight of E-84 salicylic acid metal complex

[Comparative Example 1]
100 parts by weight carbon black (Mitsubishi Kasei # 44) 10 parts by weight branched ester wax (WEP-5, Japanese fats and oils, no particle size) 5 parts by weight
TP-302 of quaternary ammonium salt molybdenum complex (Hodogaya Chemical) 1 part by weight

[Comparative Example 2]
Styrene-MMA copolymer (Glass transition 66 ° C., containing 0% THF insoluble content) 100 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Polypropylene (Mitsui Chemicals, no granulation) 9 parts by weight
Metallic azo dye Bontron S-34 (Orient Chemical) 1 part by weight

After kneading using the biaxial extruder under the kneading conditions described in Table 1 with the above formulation, rolling with cooling and quenching, followed by pulverization and classification, the weight average particle diameter of 7 μm described in Table 1 was obtained. Thereafter, 1.0 part by weight of silica fine powder (R-972: manufactured by Client Japan) and 1.0 part by weight of tin oxide having an average particle diameter of 1.5 μm and an electric resistance of 8 × 10 ³ Ω · cm were added using a Henschel mixer. The toner was obtained by mixing.
This toner was mixed with a carrier coated with a silicone resin on ferrite particles having an average particle diameter of 50 μm at a toner concentration of 4.0% to prepare a developer.

Details of Examples 3 and 4 and Comparative Example 3 of the one-component magnetic toner will be described below.
[Example 3]
Styrene-vinyl methyl ether copolymer (glass transition point 70 ° C., containing 15% THF-insoluble matter) 50 parts by weight polyester resin (glass transition point 64 ° C., containing THF-insoluble matter 5%) 50 parts by weight ferrite fine particles [FPR -102 (manufactured by TDK Corporation) 80 parts by weight zirconium salicylate (TN-105, manufactured by Hodogaya Chemical Co., Ltd.) 3 parts by weight ethylene propylene copolymer (average particle size adjusted to 30 to 280 μm) 7 parts by weight

[Example 4]
Styrene-methyl acrylate copolymer (glass transition point 65 ° C., containing 10% THF insoluble matter) 100 parts by weight ferrite fine particles [FPR-102 (manufactured by TDK Corporation) 50 parts by weight aluminum salicylate (E-88, Orient Chemical) 1 part by weight candelilla wax (average particle size adjusted to 50 to 150 μm) 3 parts by weight

[Comparative Example 3]
Styrene-methyl acrylate copolymer (glass transition point 68 ° C., containing 50% THF insoluble matter) 100 parts by weight ferrite fine particles [FPR-102 (manufactured by TDK Corporation) 80 parts by weight aluminum salicylate (E-88, Orient Chemical) 3 parts by weight Candelilla wax (no sizing) 3 parts by weight

After preliminary mixing using a Henschel mixer [FM10B manufactured by Mitsui Miike Chemical Co., Ltd.], the mixture was kneaded using a biaxial kneader [PCM-30 manufactured by Ikegai Co., Ltd.]. Next, after pulverizing using a supersonic jet pulverizer, Labojet [manufactured by Nippon Pneumatic Industry Co., Ltd.], the particles are classified by an airflow classifier [MDS-I manufactured by Nippon Pneumatic Industry Co., Ltd.], and toner particles having a particle diameter D50 of 8 μm. Got. Next, 100 parts of toner particles were mixed with 0.5 parts of colloidal silica [Aerosil R972: manufactured by Nippon Aerosil Co., Ltd.], tin oxide having an average particle size of 2.3 μm and an electric resistance of 6 × 10 ⁷ Ω · cm in a sample mill. Thus, Examples 3 and 4 and Comparative Example 3 were obtained.

Details of Examples 5 and 6 and Comparative Example 4 of the full-color two-component toner will be described below.
(Create master batch)
Using linear polyester resin M-1 (glass transition point 63 ° C., THF insoluble content 0%), pigment, polyester resin, and pure water were mixed at a ratio of 1: 1: 0.5, It knead | mixed with the roll. Kneading was performed at 60 ° C., and then the roll temperature was raised to 120 ° C. to evaporate water and prepare a master batch in advance.
・ Cyan toner master batch formulation: (TB-C)
Binder resin M-1 100 parts cyan pigment (pigment blue 15-3) 100 parts pure water 50 parts magenta toner formulation: (TB-M)
Binder resin M-1 100 parts Magenta pigment (pigment ReD 122) 100 parts Pure water 50 parts Yellow toner formulation: (TB-Y)
Binder resin M-1 100 parts Yellow pigment (pigment yellow 180) 100 parts Pure water 50 parts Black toner formulation: (TB-K)
Binder resin M-1 100 parts Black pigment (carbon black) 100 parts Pure water 50 parts

[Example 5]
・ Cyan toner prescription:
Polyester resin (M-1) 50 parts Polyester resin (glass transition point 63 ° C., THF insoluble content 5%) 50 parts Masterbatch (TB-C) 20 parts E-84 2 parts carnauba wax (Orient Chemical Co., Ltd.) Toa Kasei Co., Ltd., sized to 50-100 μm) 4 parts ・ Magenta toner formulation:
Same formula for cyan toner except that the master batch was 18 parts (TB-M).
・ Yellow toner prescription:
Same formula for cyan toner except that the master batch was 20 parts (TB-Y).
・ Black toner prescription:
Polyester resin (M-1) 40 parts Polyester resin (Glass transition point 63 ° C., 38% THF insolubles) 60 parts Orient Chemical Co., Ltd. E-84 2 parts Carnauba wax (Toa Kasei, particle size adjusted to 50-100 μm) Granulated) 4 parts carbon black (Mitsubishi Kasei # 44) 8 parts

[Example 6]
・ Cyan toner prescription:
Polyester resin (glass transition point 58 ° C, THF insoluble content 0%) 60 parts polyester resin (glass transition point 60 ° C, THF insoluble content 10%) 40 parts masterbatch (TB-C) 20 parts zirconium salicylate (TN) -105, manufactured by Hodogaya Chemical Co., Ltd.) 1 part Carnauba wax (Toa Kasei Co., Ltd., sized to a particle size of 30-80 μm) 3 parts magenta toner formulation:
Same formula for cyan toner except that the master batch was 18 parts (TB-M).
・ Yellow toner prescription:
Same formula for cyan toner except that the master batch was 20 parts (TB-Y).
・ Black toner prescription:
Same formula for cyan toner except that the master batch was 16 parts (TB-K).

[Comparative Example 4]
・ Cyan toner prescription:
Polyester resin (glass transition point 58 ° C., THF insoluble content 3%) 100 parts master batch (TB-C) 20 parts salicylic acid zirconium salt (TN-105, manufactured by Hodogaya Chemical Co., Ltd.) 1 part ester wax (Nippon Yushi, WEP- 6. No sizing) 8 parts-Magenta toner formulation:
Same formula for cyan toner except that the master batch was 18 parts (TB-M).
・ Yellow toner prescription:
Same formula for cyan toner except that the master batch was 20 parts (TB-Y).
・ Black toner prescription:
Same formula for cyan toner except that the master batch was 16 parts (TB-K).

The material was premixed using a Henschel mixer [FM10B manufactured by Mitsui Miike Chemicals Co., Ltd.] so that the material had the same formulation, and then the kneaded material temperature was 120 ° C. in a biaxial kneader [PCM-30 manufactured by Ikegai Co., Ltd.]. Kneaded. Then, after finely pulverizing using a supersonic jet crusher lab jet [manufactured by Nippon Pneumatic Kogyo Co., Ltd.], it is classified by an airflow classifier [MDS-I made by Nihon Pneumatic Kogyo Co., Ltd.] and the volume average particle diameter is about 7 μm. Toner particles (Examples 5 and 6 and Comparative Example 4) were obtained. Then, 100 parts of toner particles were mixed with 1.0 part of hydrophobic colloidal silica having an average particle diameter shown in Table 1 and tin oxide having an average particle diameter of 1.0 μm and an electric resistance of 3 × 10 ² Ω · cm in a sample mill. Thus, the toner of the present invention was obtained.
7 parts by weight of this toner was mixed with 93 parts by weight of a silicone-coated ferrite carrier having an average particle diameter of 35 μm to obtain a developer.

The following was used as an image evaluation apparatus.
Monochrome toner: Ricoh copier Imagio Neo 900 Pro remodeling machine Magnetic toner: (LP3420: Ricoh) remodeling machine Full color toner: IPSIO CX82005100 remodeling machine

The image evaluation method was as follows.
Run 5000 sheets of A4 paper with 5% image area. After that, two black A3 sheets were output as a solid image for black monochrome on a monochrome machine and yellow, cyan, magenta, and black monochrome on a full color machine.
(1) Vitiligo: The number of white spots (white spots) appearing on the solid image was counted.
(2) Solid uniformity: The image density at four corners and one center of A3 paper was measured and ranked according to the difference. The image density was measured using a gloss meter manufactured by Nippon Denshoku Industries Co., Ltd. under the condition of an incident angle of 60 °.
Solid uniformity = (maximum image density value−minimum image density value) × 100 (%)
Average image density at 5 locations Rank 5: Less than 15% Rank 4: 15-30%
Rank 3: 31-50%
Rank 2: 51-70%
Rank 1: 71% or more (1) Image streaks: The streaks appearing on solid images were counted.

Table 1 below shows the measurement results and evaluation of Examples 1 to 6 described above. Table 2 shows the measurement results and evaluations of Comparative Examples 1 to 4.

1 is a schematic diagram illustrating a configuration of an embodiment of an image forming apparatus according to the present invention. 1 is a schematic diagram illustrating a configuration of a charging device used in an image forming apparatus of the present invention. 3 is a cross-sectional view of a charging roller used in the image forming apparatus of the present invention. FIG. It is the figure which represented the shape of the toner typically in order to demonstrate shape factor SF-1. 1 is a schematic diagram illustrating a configuration of a developing device used in an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrostatic latent image carrier 2 Toner conveyance member 3 Toner layer thickness regulating member 4 Developing device 5 Agitating blade 6 Toner 7 Toner tank 8 Supply roller 10 Intermediate transfer belt (intermediate transfer member)
14 Charging device 14a Charging roller 14b Charging cleaning member 18 Image forming means 19 Pressure spring 21 Exposure device 25 Fixing device 40 Photosensitive member (latent image carrier)
22 Secondary transfer device 62 Primary transfer means 100 Copier main body 200 Paper feed table 300 Scanner 400 Automatic document feeder

Claims (21)

An image carrier for carrying a latent image;
A charging device for charging the surface of the image carrier;
An exposure device that forms a latent image on the surface of the charged image carrier;
An image forming apparatus comprising: a developing device that develops a latent image on an image carrier with toner on a developing roller;
The charging device charges the surface of the image carrier with a charging member having conductive fine particles interposed therebetween, and
An image forming apparatus, wherein the toner is obtained by externally adding at least conductive fine particles to toner base particles, and the dynamic friction coefficient of the toner base particles is in the range of 0.15 to 0.50. The image forming apparatus according to claim 1.
The toner contains 2 to 15 wt% of a component having a molecular weight of less than 1000 as a THF soluble component by GPC.
An image forming apparatus. The image forming apparatus according to claim 1, wherein
The toner has a glass transition point Tg of the toner.
The ratio (G′1 / G′2) of the storage elastic modulus G′1 at Tg−5 ° C. and the storage elastic modulus G′2 at Tg + 5 ° C. is in the range of 1-30, and
The storage elastic modulus G′2 at Tg + 5 ° C. is in the range of 6 × 10 ⁶ to 1 × 10 ⁸ (Pa).
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus includes a transfer device that transfers a visualized toner image on the image carrier to a recording medium, and the transfer residual toner on the image carrier is collected by a developing device. Forming equipment. The image forming apparatus according to claim 1,
The image forming apparatus includes a plurality of developing devices. The image forming apparatus according to claim 1,
In the image forming apparatus, the peripheral speed of the developing roller is 240 mm / sec or more. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the toner contains a release agent. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the toner has a shape factor SF-1 in the range of 100 to 180. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the toner contains a magnetic material. The image forming apparatus according to claim 1,
The image forming apparatus uses a mixture of toner and a magnetic carrier coated with a resin. A process cartridge used in the image forming apparatus according to claim 1,
The process cartridge integrally supports an image carrier that carries an electrostatic latent image and at least a developing device that is disposed to face the image carrier that carries an electrostatic latent image. A process cartridge that is removable. An image carrier that carries a latent image, a charging device that charges the surface of the image carrier, an exposure device that forms a latent image on the surface of the charged image carrier, and a toner on the developing roller that transfers the latent image on the image carrier A toner that is used in an image forming apparatus that charges the surface of the image carrier with a charging member having conductive fine particles interposed therebetween.
The toner having a dynamic friction coefficient in the range of 0.15 to 0.50. The toner according to claim 12.
The toner is characterized in that the THF soluble component by GPC contains 2 to 15 wt% of a component having a molecular weight of less than 1000. The toner according to claim 12 or 13,
The toner has a glass transition point Tg of the toner.
The ratio (G′1 / G′2) of the storage elastic modulus G′1 at Tg−5 ° C. and the storage elastic modulus G′2 at Tg + 5 ° C. is in the range of 1-30, and
A toner having a storage elastic modulus G′2 at Tg + 5 ° C. in the range of 6 × 10 ⁶ to 1 × 10 ⁸ (Pa). The toner according to any one of claims 12 to 14,
The image forming apparatus includes a transfer device that transfers a visualized toner image on the image carrier to a recording medium, and the transfer residual toner on the image carrier is collected by a developing device. . The toner according to any one of claims 12 to 15,
In the image forming apparatus, the peripheral speed of the developing roller is 240 mm / sec or more. The toner according to any one of claims 12 to 16,
The toner contains a release agent. The toner according to any one of claims 12 to 17,
The toner has a shape factor SF-1 in the range of 100 to 180. The toner according to any one of claims 12 to 18,
The toner contains a magnetic substance. The toner according to any one of claims 12 to 18,
The toner is characterized in that the toner and a magnetic carrier coated with a resin are mixed and used. The toner according to any one of claims 12 to 20,
The image forming apparatus integrally supports an image carrier that carries an electrostatic latent image and at least a developing device that is disposed to face the image carrier that carries an electrostatic latent image. A toner comprising a removable process cartridge.