JP2006145811A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an image forming apparatus in which void generation in transfer due to toner aggregation at a contact part of a transfer belt and a photoreceptor is prevented and transfer belt contamination is effectively suppressed, and in which particularly even when printed images are continuously obtained at a high speed over a prolonged period of time, printing quality with high reliability, high definition and high image quality can be maintained. <P>SOLUTION: An intrusion amount i of the transfer belt into a surface of the photoreceptor is in a range of 0%<i≤5% of the diameter d of the photoreceptor. A toner used is a monocomponent toner having toner particles including a binder resin and a colorant, and an inorganic fine powder, a uniaxial collapse stress of the toner under a maximum consolidation stress of 5 kPa is 0.1-3.0 kPa, and a uniaxial collapse stress of the toner under a maximum consolidation stress of 20 kPa is 2.5-6.0 kPa. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method and an image forming apparatus used in an electrophotographic method, an electrostatic recording method, a magnetic recording method, and a toner jet recording method, and in particular, a toner image on a photoconductor while conveying a transfer material. The present invention relates to an image forming method and an image forming apparatus using an endless transfer conveying means for transferring the toner onto the transfer material.

  As an image forming method conventionally used, many methods such as an electrophotographic method, an electrostatic recording method, a magnetic recording method, and a toner jet recording method are known. For example, there are electrophotographic methods described in Patent Documents 1 to 3, generally using a photoconductive substance, and using various means, an electric latent image (electrostatic latent image) is formed on the photoreceptor. Image) and then developing the latent image with toner, transferring the toner image onto a transfer material such as paper, if necessary, and then heating, pressurizing, heating and pressurizing, or solvent vapor. A system is known in which the transferred toner image is fixed to obtain a printed image, while the toner remaining on the photoreceptor without being transferred is cleaned by various cleaning means, and the above-described steps are repeated. .

  In recent years, output devices using such an image forming method, for example, image forming devices such as copiers, laser beam printers, LED printers, facsimiles, and printing devices have become smaller, lighter, faster, and more Higher image quality and higher reliability have been strictly pursued. On the other hand, the application fields of these output devices are expanding from the personal use to the professional use, and in particular, full-fledged as light printing (print-on-demand capable of high-mix low-volume printing; POD). Therefore, the performance required for image forming systems and toners has become higher.

  Assuming light printing applications, the performance that is required to be improved from the prior art is particularly high-quality print images, high-speed printability, high reliability, and high durability. It is necessary to cope with a wide variety of transfer materials that are generally used. Problems to be overcome in order to handle a wide variety of transfer materials include the ability to maintain stable transportability for transfer materials with various characteristics (for example, material, thickness, size), and excess and deficiency. There is no need to transfer the toner image on the photosensitive member onto the transfer material.

  As a transfer means, a type using corona discharge is widely used because of its relatively simple structure. However, the transfer means using corona discharge has a narrow transfer material adsorbing area on the photosensitive member, which is a toner image carrier, and lacks stability in transportability. In some cases, satisfactory results could not be obtained. Therefore, using a transfer medium that can run endlessly, such as an endless belt or a rotating cylinder, the transfer material is sandwiched and conveyed between the photosensitive member and an electric field having a polarity opposite to the charged polarity of the toner on the photosensitive member. Transfer means (hereinafter referred to as a transfer belt) for applying and electrostatically transferring a toner image on a photoreceptor onto a transfer material has been used. Since the transfer belt can hold and transfer the transfer material between the photosensitive member and the transfer belt, the transfer belt and the photosensitive member can be maintained stably regardless of the material, thickness and size of the transfer material. By adjusting the contact pressure with the sensor, even when the printing speed is high, transfer deviation and transfer deviation are unlikely to occur, and the transfer material adsorption area (transfer nip) to the photoconductor can be controlled, resulting in high transfer quality. Can be maintained. However, since the transfer belt needs to convey and transfer the transfer material to and from the photoconductor, a transfer current needs to be supplied to the photoconductor side via the transfer material at a contact portion with the photoconductor. For this reason, it is necessary to press the transfer belt against the photosensitive member with an arbitrary pressure (pressing). In this case, since the toner image on the photosensitive member is also subjected to pressure from the transfer belt side, toner aggregation easily occurs. As a result, the toner aggregate easily adheres to the surface of the photosensitive member, and the degree of adhesion is strong. There are cases where the transfer is hindered (transfer failure) and an image defect occurs. This image defect is particularly prominent in line images, and is called “transfer dropout” because part of the line (mainly the central part) is lost. Has been.

  To deal with such a problem, Patent Document 4 discloses a technique in which specific fine particles acting as spacer particles are added to the toner to prevent adhesion to the photoreceptor due to toner aggregation. The technique described in Patent Document 4 assumes a light printing application, for example, every minute, although the effect of preventing transfer dropout is sufficiently recognized when a printer with a relatively low print speed or print volume is assumed. When printing several hundreds of thousands of sheets continuously at a printing speed of 60 sheets or more, the effect on the developability caused by the addition of spacer particles to the toner (charging inhibition) and the improvement of high durability stability are improved. There is room for.

  In Patent Documents 5 to 6, by adding a plurality of additives to the toner, the charge amount of the toner is stabilized at a low level or the toner fluidity is improved, so that the transfer between the transfer belt and the photosensitive member is improved. Means for preventing toner aggregation due to pressure and maintaining the transfer rate are disclosed. However, the methods described in these Patent Documents 5 to 6 may cause a reduction in the effect of preventing transfer dropout, assuming light printing applications (that is, high-speed printing is possible and used continuously for a long period). There is a need for further improvements in terms of maintaining high-definition and high-quality print quality stably over the long term.

  Furthermore, according to the methods described in Patent Documents 4 to 6, the additive added to the toner has a purpose of adding to the cohesion of the toner and the toner charging characteristics are somewhat sacrificed. Therefore, depending on the case, the additive or the toner particles to which the additive is attached behaves as a reversal component with respect to the toner polarity and is developed in a non-image area on the photosensitive member, and this is transferred to the transfer belt surface between transfer materials. The transfer belt could be soiled. Various cleaning mechanisms have been devised for the purpose of reducing the contamination of the transfer belt. However, it is very difficult to simultaneously clean a substance (for example, a reversal component) that has significantly different charging characteristics from the toner. Furthermore, assuming light printing applications, when the printing operation is repeated continuously at a high speed for a long period of time, the transfer belt becomes conspicuous, and as a result, the back surface of the transfer material (that is, the contact with the transfer belt). Surface) may become dirty or the transferability of the transfer belt may be reduced, and further improvements are required.

US Pat. No. 2,297,691 Japanese Patent Publication No.42-23910 Japanese Patent Publication No.43-24748 Japanese Patent Laid-Open No. 04-274443 Japanese Patent Application Laid-Open No. 07-199681 JP 2003-098732 A

  An object of the present invention is to provide an image forming method and an image forming apparatus that solve the above-described problems. That is, the present invention uses a conductive substrate and a photosensitive member having at least a photoconductive layer on the conductive substrate, and applies a charge opposite in polarity to the toner charging polarity to the toner image developed on the surface of the photosensitive member. In the image forming method and the image forming apparatus for transferring the image by bringing it into contact with the transfer material conveyed on the transfer belt, the transfer belt is prevented from being lost due to toner aggregation at the contact area between the transfer belt and the photosensitive member. An image forming method capable of effectively suppressing contamination and maintaining high-quality, high-definition and high-quality print quality even when printing images are obtained continuously at a high speed for a long period of time. An object of the present invention is to provide an image forming apparatus.

  The present invention uses a conductive substrate and a photosensitive member having at least a photoconductive layer on the conductive substrate, charges the surface of the photosensitive member, forms an electrostatic latent image on the photosensitive member by exposure, The electrostatic latent image is developed with toner to form a toner image, and the toner image is brought into contact with a transfer material conveyed on an endless transfer conveying means to which a charge opposite in polarity to the charging polarity of the toner is applied. In the image forming method for transfer, the endless transfer conveyance means is a transfer belt, and the transfer belt is provided at least two or more installed on the upstream side and the downstream side in the conveyance direction of the portion in contact with the photoreceptor. The amount of penetration i of the transfer belt with respect to the surface of the photosensitive member is within a range of 0% <i ≦ 5% of the photosensitive member diameter d at the contact portion with the photosensitive member. Toner particles containing at least a binder resin and a colorant And a one-component toner having at least an inorganic fine powder. The toner has a uniaxial collapse stress at a maximum compaction stress of 5 kPa of 0.1 to 3.0 kPa and a single toner at a maximum compaction stress of 20 kPa. The present invention relates to an image forming method, wherein the axial collapse stress is 2.5 to 6.0 kPa.

  The inorganic fine powder contained in the toner used in the image forming method of the present invention is preferably at least one oxide selected from magnesium oxide, alumina, zinc oxide and titanium oxide.

  The content of the inorganic fine powder contained in the toner used in the image forming method of the present invention is preferably 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles.

  The photoreceptor used in the image forming method of the present invention comprises a conductive substrate, a photoconductive layer containing at least amorphous silicon and amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride on the conductive substrate. It is preferable to provide a surface protective layer.

  The toner particles constituting the toner used in the image forming method of the present invention preferably contain a magnetic substance.

  The toner used in the image forming method of the present invention is preferably positively charged.

  Furthermore, the present invention uses a conductive substrate and a photosensitive member having at least a photoconductive layer on the conductive substrate, uniformly charges the surface of the photosensitive member, and forms an electrostatic latent image on the photosensitive member by exposure. And forming the toner image by developing the electrostatic latent image with toner, and transferring the toner image onto an endless transfer conveying means to which a charge having a polarity opposite to that of the toner is applied. In the image forming apparatus for transferring in contact with the image forming apparatus, the endless transfer / conveying means is a transfer belt, and the transfer belt is disposed at least on the upstream side and the downstream side in the conveyance direction of the portion in contact with the photosensitive member. The amount of penetration i of the transfer belt with respect to the surface of the photosensitive member is in a range of 0% <i ≦ 5% of the diameter of the photosensitive member d. The toner contains at least a binder resin and a colorant. A one-component toner having at least particles and an inorganic fine powder, the toner has a uniaxial collapse stress of 0.1 to 3.0 kPa at a maximum compaction stress of 5 kPa, and a maximum compaction stress of the toner of 20 kPa The present invention relates to an image forming apparatus having a uniaxial collapse stress of 2.5 to 6.0 kPa.

  The inorganic fine powder contained in the toner used in the image forming apparatus of the present invention is preferably at least one oxide selected from magnesium oxide, alumina, zinc oxide, and titanium oxide.

  The content of the inorganic fine powder contained in the toner used in the image forming apparatus of the present invention is preferably 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles.

  Further, a photoreceptor used in the image forming apparatus of the present invention includes a conductive substrate, a photoconductive layer containing at least amorphous silicon, and amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride on the conductive substrate. It is preferable to provide a surface protective layer.

  The toner particles constituting the toner used in the image forming apparatus of the present invention preferably contain a magnetic material.

  The toner used in the image forming apparatus of the present invention is preferably positively charged.

  According to the present invention, a conductive substrate and a photoreceptor having at least a photoconductive layer on the conductive substrate are used, and a toner image developed on the surface of the photoreceptor is charged with a charge having a polarity opposite to that of the toner. In an image forming method and an image forming apparatus for transferring a transfer material in contact with a transfer material conveyed on an applied transfer belt, the amount i of penetration of the transfer belt with respect to the surface of the photosensitive member at a contact portion between the transfer belt and the photosensitive member The diameter d is in a range of 0% <i ≦ 5%, and the toner is a one-component toner having toner particles containing at least a binder resin and a colorant and an inorganic fine powder, and the toner has a maximum compaction stress of 5 kPa to 20 kPa. By controlling the relationship between the maximum consolidation stress (X) kPa and the uniaxial collapse stress (U) kPa in an arbitrary range, the printer can be used in a state where it can be continuously printed at high speed for a long period of time. In addition, the transfer belt and the photosensitive member are prevented from being punctured due to toner aggregation at the contact portion of the photoconductor, and the transfer belt contamination is effectively suppressed, so that high-quality and high-quality print quality can be stably maintained over a long period of time. Can continue.

  Embodiments of the present invention will be described below.

  As a result of examining the effect of mitigating the toner aggregation phenomenon due to the pressing factor applied to the contact portion (also referred to as a transfer nip portion) between the transfer belt and the photosensitive member, the present inventors have obtained a print image continuously at a high speed for a long period of time. Has found the grounds that it is insufficient to prevent the transfer drop-out phenomenon using the conventional technique for mitigating toner aggregation. In other words, for example, when fine particles capable of spacer action are added to the toner, the spacer particle release phenomenon always occurs, although there is a difference in degree. It became clear that there is. In addition, when adding some fine particles for the purpose of controlling the fluidity and chargeability of the toner, a method for controlling the toner charging characteristics to be low is often used, and in some cases, the reversal component is increased. It has been clarified that an electrostatic aggregating action tends to cause a transfer dropout or a transfer belt contamination phenomenon. These tendencies tend to appear remarkably with increasing print speed and print volume (number of prints output per unit period).

  From such a background, the present inventors have developed a mitigating effect on the toner aggregation phenomenon due to a pressing factor applied to the contact portion between the transfer belt and the photosensitive member, and a transfer belt contamination suppressing effect. It was judged that the physical spacer effect, electrostatic apparent chargeability control, or fluidity control should not be relied on, and the fundamental review of the constituent materials used for the toner proceeded. In order to elucidate the toner aggregation phenomenon due to the pressing factor applied to the contact portion between the transfer belt and the photoconductor, the present inventors first know the powder characteristics of the toner under the compacted state and can control it. Thought that should be developed. As a result of the examination under such a policy, it is possible to grasp the behavior of the toner under the compaction state by obtaining the maximum compaction stress (X) kPa and uniaxial collapse stress (U) kPa of the toner. It came to be able to do it. Furthermore, the present inventors can control the above-mentioned toner powder characteristics within a specific range even when a printed image is obtained at high speed and continuously for a long time by using a transfer belt, thereby preventing the effect of transfer omission. It was also found that the effect of suppressing transfer belt contamination can be stably maintained over a long period of time. That is, it was found that it is very important to control the relationship between the maximum compaction stress (X) kPa and the uniaxial collapse stress (U) kPa in the range of the maximum compaction stress of the toner from 5 kPa to 20 kPa. The toner powder characteristics under this compacted state are due to the effect of preventing transfer dropout and transfer belt contamination in a system that performs printing work for a long time at a high speed as in light printing applications, that is, a system that places a heavy load on the toner. It can be said that it is an indispensable physical property for maintaining the inhibitory effect stably over the long term.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings, and the relationship with the powder characteristics of the toner in a compacted state will be further described.

  FIG. 1 shows an example of this embodiment, and shows a schematic diagram of a transfer process and a transfer belt cleaning process.

  The photoconductor 11 is provided with a photoconductive layer on a cylindrical conductive substrate, and the transfer belt 12 includes two or more transfer belts 12 arranged in parallel to each other in a direction substantially perpendicular to the transfer material transport direction. It is supported by rollers (in FIG. 1, three rollers, a driving roller 13, a driven roller 14, and a cleaning backup roller 17), and is driven to rotate in the direction of the arrow by a driving motor (not shown). The transfer belt 12 conveys the transfer material 19 in the direction of the arrow while the toner on the photoconductor 11 is pressed onto the transfer material 19 at a contact portion with the photoconductor 11 (that is, a transfer nip). Transcript. A bias roller 15 serving as a transfer charge applying unit that applies a transfer bias by applying a transfer bias and a high-voltage power source 16 that applies a voltage to the bias roller 15 are attached to the transfer site. The bias roller 15 is provided so as to contact the inside of the transfer belt 12 at a position slightly downstream of the transfer nip portion in the rotation direction of the transfer belt 12. The bias roller 15 constitutes a contact electrode for applying a charge having a polarity opposite to the charge polarity of the toner developed on the photoreceptor 11 to the transfer belt. The transfer charge applying means may be a charger using corona discharge or a brush-like charger. The installation position of the transfer charge applying unit is not limited to the downstream side in the transfer belt rotation direction with respect to the transfer nip portion, and may be installed in the upstream direction.

  In the present invention, the transfer belt 12 needs to be pressed against the surface of the photoconductor 11 with an appropriate pressure from the side of the transfer belt 12 at the contact portion with the photoconductor 11, and as shown in FIG. 12 is required to be in a range of 0% <i ≦ 5% with respect to the diameter d of the photoconductor 11. At the drive roller 13 site, the transfer belt 12 and the transfer material 19 are separated by curvature separation. A fur brush 18 is installed on the cleaning backup roller 17 at a position opposite to the transfer belt 12, and the transfer belt 12 is rotated in the advancing direction and the counter direction to clean the surface of the transfer belt.

  As is clear from the schematic diagram of FIG. 1, when a transfer belt is used, the toner developed on the photoconductor is always pressed by the transfer belt side in the transfer process and is in a compacted state. Since it is structurally impossible to avoid the pressurization state itself in this transfer process, the toner has a powder characteristic that enables it to be easily unraveled (that is, not easily packed) even in a compacted state. It is preferable. That is, the toner used in the present invention has a uniaxial collapse stress of 0.1 to 3.0 kPa when the maximum compaction stress is 5 kPa, and the uniaxial collapse stress of the toner when the maximum compaction stress is 20 kPa is 2.5. It is ˜6.0 kPa.

  The greatest feature of the present invention is that the toner layer compacted with an arbitrary load is easily released from the relationship between the maximum compaction stress (X) and the uniaxial collapse stress (U) of the toner, that is, the densely packed toner layer. It is possible to evaluate the cohesion between toner particles. The uniaxial collapse stress (U) of the present invention refers to a stress relating to the ease of unraveling of the toner layer that has been pressed at the contact portion between the transfer belt and the photosensitive member in the transfer step, and represents the cohesive force between toner particles. Can be treated as an indicator. Further, the maximum consolidation stress (X) in the present invention represents the stress applied to the toner layer in the compacted state formed by the pressure received at the contact portion between the transfer belt and the photosensitive member. In the present invention, when determining the maximum consolidation stress of the toner, the lower limit of the maximum consolidation stress is set to 5 kPa and the upper limit is set to 20 kPa as a range in which the measurement error can be ignored. The maximum consolidation stress of 20 kPa means that the upper limit at which the toner can exist in powder, that is, if the stress higher than that is applied, the toner is completely packed. In practice, in the embodiment of the present invention, there can be no situation where the maximum compaction stress of the toner at the transfer contact portion exceeds 20 kPa. Therefore, in order to evaluate the powder characteristics of the toner, that is, the cohesion between toner particles, It is preferable to discuss the maximum consolidation stress of 20 kPa or less. In the present invention, the transition of the uniaxial collapse stress within the range of the maximum compaction stress was obtained, and this characteristic value was evaluated as an index of the cohesive force between toner particles of the toner layer that became compact in the transfer process.

  That is, in the present invention, the uniaxial collapse stress of the toner at a maximum consolidation stress of 5 kPa is 0.1 to 3.0 kPa, and the uniaxial collapse stress of the toner at a maximum consolidation stress of 20 kPa is 2.5. In the case of ˜6.0 kPa, even when the toner layer falls into a compacted state due to the pressure applied to the contact portion between the transfer belt and the photosensitive member, the toner layer is not packed and effectively prevents the transfer from being lost. be able to.

  On the other hand, a toner in which the uniaxial collapse stress when the maximum compaction stress of the toner is 5 kPa is larger than 3.0 kPa or the uniaxial collapse stress when the maximum compaction stress of the toner is 20 kPa is larger than 6.0 kPa. Below, the cohesive force between the toner particles is large, and packing occurs, resulting in transfer deficiency.

  Further, a toner having a uniaxial collapse stress of 0.1 to 3.0 kPa when the maximum consolidation stress of the toner is 5 kPa, and a uniaxial collapse stress of less than 2.5 kPa when the maximum consolidation stress of the toner is 20 kPa, The cohesive force between toner particles is so small that toner does not pack even in a compacted state, so there is no transfer dropout, but there are many cases where electrostatic chargeability is low, so transfer image quality itself is degraded. May be invited.

  In the present invention, it is preferable that the intrusion amount i of the transfer belt with respect to the surface of the photosensitive member at the contact portion between the transfer belt and the photosensitive member is in a range of 0% <i ≦ 5% of the photosensitive member diameter d. In the present invention, since the toner on the photosensitive member is pressed from the transfer belt side, the effect of preventing the transfer from falling out is exhibited. Although there is no restriction on the width, if the amount of penetration i of the transfer belt with respect to the surface of the photoconductor exceeds 5%, image quality deterioration such as transfer blur may be observed during high-speed printing operation.

  In the present invention, since the transfer belt is rotationally driven in a state where tension is applied structurally, it is necessary to have excellent bending characteristics, tear strength characteristics, etc., and rubber having a higher elastic property than a resin type belt as a material. An elastomer type belt is preferred. In particular, it is preferable to select from materials having low hygroscopicity and stable resistance, such as chloroprene rubber, urethane rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber. In this case, the structure which has a base material is more preferable.

  As described above, according to the present invention, in the toner layer under the compacted state at the contact portion between the transfer belt and the photoconductor, the cohesiveness between the toner particles is controlled within the specific range described above, so that the high-speed and long-term continuous operation can be achieved. Even in the case of obtaining a print image, it is possible to prevent the occurrence of transfer skipping, and it is possible to continue to maintain high-reliability, high-definition, and high-quality print quality.

  Incidentally, the conventional technique for preventing transfer dropout using spacer particles is fundamentally different from the present invention in that it aims at avoiding the compaction state of the toner under pressure in the transfer process. The method of adding various fine particles is intended to alleviate the compaction state of the toner by controlling the chargeability and fluidity of the toner, but does not apply external pressure to the toner, that is, powder in a powder state Since the characteristics are mentioned, the cohesive force between the toner particles in the compacted state, which is a feature of the present invention, has not been considered at all, and therefore, the function and effect for preventing the transfer omission are different from the present invention.

The maximum consolidation stress (X) and uniaxial collapse stress (U) of the toner of the present invention were measured using a shear scan TS-12 (manufactured by Sci-Tec). Share scan is Prof. Virendra M.M. The measurement is performed according to the principle of the Morcoulomb model described in “Characterizing Powder Flowability (2002.1.24)” described by Puri. Specifically, the measurement was performed in a room temperature environment (temperature 23 to 28 ° C., humidity 40 to 70%) using a linear shear cell (diameter 80 mm, capacity 140 cm ³ ). Each toner is put into this cell, and a vertical load is applied so as to be 2.5, 5, and 10 kPa, thereby producing a compacted toner layer. As a technique for realizing this toner compaction state, measurement using a shear scan is preferable in the present invention in that a sample can be prepared without individual differences while automatically detecting pressure. Next, the fracture envelope is obtained by measuring the shear stress for each vertical load stress, and the cohesive force and the internal friction angle are obtained therefrom. From this cohesive force and internal friction angle, it is possible to calculate the uniaxial collapse stress and maximum consolidation stress at each vertical load. The uniaxial collapse stress and the maximum consolidation stress calculated for each vertical load are plotted (Flow Function Plot), and the uniaxial collapse stress at an arbitrary consolidation stress is easily solved based on the slope of the plot (straight line). It was used as an index of safety. As already described, in the present invention, the measurement error can be ignored in obtaining the maximum consolidation stress. The lower limit of the maximum consolidation stress is 5 kPa, and the upper limit is 20 kPa, which is the upper limit at which the toner can exist in the powder state. It was.

  On the other hand, the present inventors have examined the relationship between toner particles and inorganic fine powders for the control of maximum compaction stress (X) and uniaxial collapse stress (U), which are toner powder characteristics under the compaction state in the present invention. It has been found that it can be easily controlled by adjusting to specific conditions.

  That is, in the present invention, when the toner particles are dispersed in water, the difference in zeta potential between the toner particles and the inorganic fine powder at the pH of the supernatant is preferably 40 mV or less. It is possible to adjust the relationship between the maximum compaction stress (X) and the uniaxial collapse stress (U) of the toner in the range of the present invention.

  The zeta potential of the toner particles at the pH of the supernatant when the toner particles are dispersed in water corresponds to the surface charge density at the pH of the powder of the toner particles. Therefore, in the present invention, it means that it is preferable to use an inorganic fine powder having a surface charge density substantially equivalent to the surface charge density on the surface of the toner particles. In general, when an inorganic fine powder is added to toner particles, it is known that van der Waals force (intermolecular force), electrostatic attractive force, liquid crosslinking force and the like are generated between the particles. According to the study by the present inventors, various attractive forces as described above are acting between the toner particles and the inorganic fine powder, but the surface charge density on the surface of the toner particles and the inorganic fine powder is controlled to be equivalent. As a result, it has been clarified that the action of relaxing (reducing) the attractive force acting between the toner particles and the inorganic fine powder works. By this action, the cohesive force between toner particles can be reduced, and the uniaxial collapse stress at the time of the maximum compaction stress of 5 kPa, which is a feature of the present invention, is 0.1 to 3.0 kPa, and It becomes easy to control the uniaxial collapse stress in the range of 2.5 to 6.0 kPa at the time of the maximum consolidation stress of 20 kPa, and in the transfer method using the transfer belt, an excellent effect of preventing the transfer from being lost. Further, in the present invention, since the surface charge density difference between the toner particles and the inorganic fine powder is controlled to be small, the toner may be used even in a situation where a print image is obtained continuously at a high speed for a long period of time. Among them, there was little generation of a charging reversal component, and a tendency to suppress transfer belt contamination was observed. That is, in the present invention, it is shown that the inorganic fine powder added to achieve the prevention of transfer dropout and the suppression of transfer belt contamination hardly inhibits the charging characteristics of the toner. Even when the transfer belt is slightly contaminated, the toner or the like adhering to the transfer belt can be easily removed by a transfer belt cleaning mechanism such as the fur brush 18 shown in FIG. In the present invention, in addition to the fact that the transfer belt is less contaminated, the reason that the adhering contaminants are easy to clean is that the main contaminant, that is, the toner used in the present invention, is added to the inorganic fine powder added. This is considered to be because there is little tendency for fine particles having a specific charging property to selectively accumulate on the transfer belt because the surface charge density difference is controlled to be small. That is, in the present invention, transfer belt contamination can be suppressed at the same time as effectively preventing transfer dropout by relaxing the cohesive force between toner particles.

  When the difference in zeta potential between the toner particles and the inorganic fine powder is larger than 40 mV, the above-described action of reducing the attractive force acting between the particles is reduced, and the toner is easily packed under the compacted state. May occur, and transfer belt contamination may occur.

  The method for measuring the zeta potential of the toner particles and inorganic fine powder in the present invention will be described below.

  In the present invention, the zeta potential of the toner particles and the inorganic fine powder can be measured using an ultrasonic zeta potential measuring device DT-1200 (manufactured by Dispersion Technology). Pure water was used as a dispersion, and a 0.5 Vol% aqueous solution of toner particles and inorganic fine powder was prepared. If necessary, a nonionic dispersant that does not affect the zeta potential is added in an amount of 0.4% by mass with respect to the particle concentration, dispersed for 3 minutes with an ultrasonic disperser, and then defoamed for about 10 minutes. Stir to make a dispersion. The pH of the supernatant was measured simultaneously with the measurement of toner particles. When measuring the inorganic fine powder, the dispersion was titrated with 1N HCl or 1N KOH as necessary, adjusted to the pH value of the supernatant of the toner particles, and the zeta potential was measured using the above apparatus.

  In the present invention, the inorganic fine powder used together with the toner particles is preferably at least one oxide selected from magnesium oxide, alumina, zinc oxide and titanium oxide. These are easy to control the difference between the surface charge density of the toner particle surface and the surface charge density of the inorganic fine powder, so that the effect of alleviating the cohesive force between the toner particles at the contact area between the transfer belt and the photoreceptor is effective. It is preferable in that it can be easily exhibited. In addition, the toner used in the present invention effectively exerts a relaxing action on the cohesive force between toner particles at the contact portion between the transfer belt and the photosensitive member, and uniformly disperses the inorganic fine powder on the toner particle surface. / When present, it is preferable that the liberation rate of the inorganic fine powder is in the range of 0.1% to 5%. When the liberation rate of the inorganic fine powder is larger than 5%, the amount of the inorganic fine powder existing in the vicinity of the toner particle surface is relatively reduced, so that the effect of reducing the cohesive force between the toner particles is reduced and the transfer omission is prevented. The effect and the effect of suppressing transfer belt contamination may be reduced.

  The liberation rate of the inorganic fine powder from the toner particles in the present invention can be measured using a particle analyzer (PT1000: manufactured by Yokogawa Electric Corporation). Measurement using a particle analyzer can be performed according to the principle described on pages 65-68 of the Japan Hardcopy 97 paper collection, for example. Specifically, the particle analyzer introduces fine particles such as toner one by one into the plasma, and can know the element of the luminescent material, the number of particles, and the particle size of the particles from the emission spectrum of the fine particles.

  For example, when toner particles to which magnesium oxide is added as an inorganic fine powder are introduced into the plasma, light emission of carbon, which is a constituent element of the binder resin, and light emission of Mg atoms are observed for each toner particle. That is, the number of toner particles can be obtained from the number of times of light emission. At that time, Mg atoms emitted within 2.6 msec from the emission of carbon atoms were regarded as simultaneously emitted Mg atoms, and subsequent Mg atoms were assumed to emit only Mg atoms. In the toner of the present invention, the fact that carbon atoms and Mg atoms emit light at the same time means that magnesium oxide is attached to the toner particle surface, and the emission of only Mg atoms means that magnesium oxide is released from the toner particles. I can say that.

  As a specific measurement method, a toner sample conditioned by leaving it to stand overnight in an environment of a temperature of 23 ° C. and a humidity of 60% was measured using helium gas containing 0.1% oxygen in the above environment. That is, carbon atoms (measurement wavelength 247.86 nm) are measured in channel 1, Mg atoms (measurement wavelength 285.21 nm) are measured in channel 3, and the number of emitted carbon atoms is 1,000 to 1,400 in one scan. Sampling is performed, and scanning is repeated until the total number of light emission of carbon atoms reaches 10,000 or more, and the light emission number is integrated. And the liberation rate was calculated | required by making it the number of the free magnesium oxide by counting the light emission number of only the Mg atom at that time. At this time, the noise cut level is 1.50V. In addition, when the release rate of alumina is measured by the same method, Al atom (396.15 nm) in channel 2, Zn atom in channel 4 (334.50 nm) in the case of zinc oxide, and titanium oxide in the case of titanium oxide In the channel 5, Ti atoms (334.90 nm) were measured, and the liberation rate was determined.

  In the present invention, the toner cohesive force mitigating action at the contact portion between the transfer belt and the photosensitive member is manifested when the toner used in the present invention contains an inorganic fine powder. The degree of effect is not proportional to the content of the inorganic fine powder, and the toner aggregation is excellent when the content of the inorganic fine powder is in the range of 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles. A force relaxation effect is exhibited, and an effect of preventing transfer dropout and a transfer belt contamination suppression effect are effectively obtained. When the amount exceeds 2.0 parts by mass, the toner aggregation mitigating effect may be increased, and the effect of preventing transfer dropout and the effect of suppressing transfer belt contamination may be reduced.

  Further, the inorganic fine powder of the present invention may be used after surface treatment with a known treating agent. In this case, the control region for the surface charge density difference between the toner particles and the inorganic fine powder is further expanded, and environmental characteristics (moisture absorption characteristics) can be improved.

  Furthermore, the toner used in the present invention preferably contains a magnetic material. When the toner particles contain a magnetic material, the controllability of the surface resistance of the toner is improved, and it becomes easier to transfer charges to and from the inorganic fine powder. The toner particles at the contact portion between the transfer belt and the photoconductor It is possible to effectively exhibit a cohesiveness relaxation action. Further, since the toner particles contain a magnetic substance, the control range of the zeta potential of the toner particles at the pH of the supernatant when the toner particles are dispersed in water can be expanded, and the surface charge density on the surface of the toner particles Since it becomes easy to control the difference in surface charge density between the toner and the inorganic fine powder, it is easy to effectively exert the cohesive action of the cohesive force between the toner particles, and control the effect of preventing transfer dropout and the effect of contamination of the transfer belt. It becomes easy to do.

  The number average particle diameter of the magnetic material contained in the toner used in the present invention is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm. The number average particle diameter of the magnetic substance in the present invention is a horizontal diameter measured using a transmission electron microscope.

  Further, the magnetic substance contained in the toner used in the present invention is preferably octahedral or binuclear from the viewpoint of fine dispersion in the toner particles. Further, the magnetic substance contained in the toner used in the present invention is preferably subjected to a treatment for applying a shearing force to the slurry during production for the purpose of improving the fine dispersibility in the toner particles.

  The amount of the magnetic material contained in the toner used in the present invention is preferably 10 to 200 parts by weight, preferably 20 to 170 parts by weight, and more preferably 30 to 150 parts by weight with respect to 100 parts by weight of the binder resin.

  Furthermore, the photoconductor used in the present invention has a photoconductive layer provided on a cylindrical conductive substrate, and includes amorphous silicon on the conductive substrate particularly when light printing applications are assumed. It is preferable to use a photoconductor provided with a photoconductive layer and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. Amorphous silicon photoconductors, for example, have higher surface hardness and excellent abrasion resistance than organic photoconductors, and also have excellent environmental characteristics, that is, moisture resistance, so they have a longer life and are used for a long time. It is excellent in stability and reliability, and is suitably used when light printing applications are assumed. However, since amorphous silicon photoconductors have extremely high surface hardness and high smoothness, when the transfer belt is pressed and transferred, toner aggregates that are consolidated at the transfer nip are attached to the photoconductor surface. It tends to be easy to do. Therefore, by using in combination with the toner containing the inorganic fine powder used in the present invention, an excellent effect of preventing the transfer from being lost can be obtained. Further, in the present invention, when the amorphous silicon-based photoreceptor is provided with a surface protective layer containing amorphous carbon or amorphous silicon nitride, the environmental resistance, that is, the moisture resistance is improved, and the effect of releasing the toner is improved. For this reason, the effect of preventing transfer omission is more effectively exhibited.

  When such an amorphous silicon photoconductor is used, in order to perform normal development as a developing method, it is necessary to expose the photoconductor portion corresponding to the non-image portion, and conversely, when performing reversal development, the image portion is exposed. It is necessary to expose the corresponding photoreceptor part. That is, in forming an electrostatic latent image, it is necessary to select whether to expose a non-image area (back scan) or to expose an image area (image scan). With regard to these exposure methods, in principle, both methods can draw the same latent image, but the charging characteristics at the edge portion of the electrostatic latent image formed on the photosensitive member are substantially negligible. There is a tendency for a difference to occur, and in consideration of the life of the exposure apparatus, exposure based on an image scanning method, that is, a reversal development method is more preferable when light printing is assumed.

  In the case of the reversal development method, when using a negatively chargeable amorphous silicon photoconductor (that is, an amorphous silicon photoconductor that holds a negative charge), a negatively chargeable toner is used, whereas a positively chargeable amorphous silicon photoconductor When the toner is used, a positively chargeable toner is used. There is no difference in image formation when using either of these, but when using a negatively charged amorphous silicon photoconductor, it is widely used as a primary charging means. If a corona discharge type charger is used, a large amount of ozone tends to be generated, and a large amount of discharge products are generated on the photoconductor, which makes it extremely difficult to clean the surface of the photoconductor. In addition, the adhesion of the toner to the surface of the photoreceptor tends to increase. For this reason, it is necessary to use, for example, a charge injection charger. In this case, although depending on the system to be used, in general, at the contact portion between the transfer belt and the photoconductor, There is a tendency that the toner layer brought into a compacted state by pressing is more likely to adhere to the surface of the photoreceptor, and transfer loss is likely to occur. On the other hand, when using a positively chargeable amorphous silicon photoconductor, the amount of ozone generated is relatively small even with a general corona discharge type primary charger. It is preferably used because it is less likely to cause problems such as when used. Therefore, in the present invention, it is preferable to use a positively chargeable amorphous silicon photoreceptor and a system using a reversal development method, that is, a positively chargeable toner.

  Regarding an example of a photoreceptor used in the present invention, comprising a conductive substrate, a photoconductive layer containing amorphous silicon on the substrate, and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. A partial cross-sectional view is shown in FIG.

  As the conductive substrate 21 shown in FIG. 2, for example, aluminum (Al) is the most common, but chromium (Cr), molybdenum (Mo), gold (Au), indium (In), niobium (Nb), It is possible to use metals such as tellurium (Te), vanadium (V), titanium (Ti), platinum (Pt), lead (Pd), iron (Fe), and alloys thereof such as stainless steel. In addition, a transparent substrate such as glass or plastic, or an insulator such as ceramic is also made into a conductive substrate by conducting a conductive treatment on its surface, that is, the surface on the side where the photoconductive layer 23 is formed. Can do.

  Further, in the present invention, an amorphous silicon-based and / or amorphous carbon-based and / or amorphous silicon nitride-based surface protective layer 23 is provided on the photoconductive layer 22.

  The photoconductive layer 22 may be organic or inorganic as long as it has photoconductivity. However, as the inorganic photoconductive layer, for example, an amorphous film in which silicon atoms contain hydrogen atoms and / or halogen atoms is used. It is preferable to use a quality material (hereinafter abbreviated as a-Si (H, X)) as a main component. Or inorganic materials, such as a-Se, can be combined suitably.

  Moreover, it is preferable that the photoconductive layer 22 contains an atom for controlling conductivity as required. The atoms that control conductivity may be uniformly distributed in the photoconductive layer 22 or may be unevenly distributed. Examples of the atoms that control conductivity include so-called impurities in the semiconductor field, atoms belonging to Group III of the periodic table that give p-type conduction characteristics (hereinafter abbreviated as “Group III atoms”), or n-type conduction. An atom belonging to Group V of the periodic table giving characteristics (hereinafter abbreviated as “Group V atom”) can be used. Specific examples of the group III atom include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). In particular, boron (B), aluminum (Al), and gallium. (Ga) is preferred. Specific examples of the group V atom include phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi), and phosphorus (P) and arsenic (As) are particularly preferable. By appropriately doping these impurities, the charging polarity of the amorphous photoreceptor can be determined.

  Further, in order to improve the photosensitive characteristics, the photoconductive layer 22 may have a plurality of layers such as a lower photoconductive layer 25 and an upper photoconductive layer 26. Although there is no limitation in particular as the film thickness of the photoconductive layer 22, about 15-50 micrometers is suitable from relationships, such as manufacturing cost.

  The surface protective layer 23 is a non-single crystal (preferably amorphous) material (a-SiC (H, X)) containing a silicon atom as a base and containing a carbon atom and, if necessary, a hydrogen atom and / or a halogen atom. A non-single crystal carbon (preferably amorphous carbon) (a-C (H, X)) containing a hydrogen atom and / or a halogen atom as necessary, a silicon atom as a parent, It is formed of a non-single crystal (preferably amorphous) material (a-SiN (H, X)) containing a nitrogen atom and, if necessary, a hydrogen atom and / or a halogen atom, or a combination thereof. In the present invention, since the photoreceptor has such a surface protective layer, the contact property with the transfer belt is improved, and the releasing effect on the surface of the photoreceptor is improved, thereby improving the transfer dropout. The action tends to be expressed more efficiently.

  Although there is no limitation in particular as the film thickness of the surface protective layer 23, about 0.05-2 micrometers is suitable from a viewpoint that what is necessary is just to exist at the minimum necessary for actual use. In addition, it is preferable to provide an interface layer (or antireflection layer) 27 in which the interface composition between the photoconductive layer 22 and the surface protective layer 23 is continuously changed, and to control the interface reflection in this portion. In addition, the surface of the conductive substrate 21 is preferably formed into a concavo-convex groove or dimple shape by cutting or the like. By adopting such a surface shape, it is possible to make it difficult to see the interference fringes caused by the reflection of the exposure light that has reached the surface of the conductive substrate 21, and the substrate of the film formed on the conductive substrate 21. The adhesion with 21 is also improved. Further, the shape of the conductive substrate may be as desired according to the driving method of the photosensitive member.

  Of course, in addition to these layers, various functional layers such as the charge injection blocking layer 24 as shown may be provided as necessary. For example, by providing the charge injection blocking layer 24 and appropriately selecting the dopant from group III atoms, group V atoms, etc., charge polarity control such as positive charge or negative charge becomes possible.

Further, in the present invention, in order to make the relationship between the maximum compaction stress (X) and the uniaxial collapse stress (U) of the toner within a specific range, the half-value width W with respect to the peak particle size D in the toner number-based particle size distribution. However, it is preferable to satisfy | fill the relationship of following formula (1).
2.06D-9.0 ≦ W ≦ 2.06D-7.5 (1)

  When the relationship between the half-value width W and the peak particle size D is W> 2.06D-7.5, it means that the toner particle size distribution is broad, and the width of the toner charge distribution is widened and the charge variation Is likely to occur, and the cohesive force between the toner particles at the contact portion between the transfer belt and the photoreceptor increases. When the relationship between the half-value width W and the peak particle size D is W <2.06D-9.0, it means that the toner particle size distribution is very sharp, and the toner charge distribution width is narrow and uniform. Although the cohesive force between the toner particles in the compacted state at the contact portion between the transfer belt and the photoconductor is reduced, to produce a toner having a particle size distribution in this range, for example, reducing the absorption rate It may accompany it and is not realistic in manufacturing.

  In the present invention, the particle size distribution of the toner can be measured using a Coulter Multisizer IIE (manufactured by Coulter). The electrolyte used in the measurement with this apparatus is an approximately 1% NaCl aqueous solution prepared using primary sodium chloride, or a commercially available electrolyte such as ISOTON®-II (manufactured by Coulter Scientific Japan Co., Ltd.). ) Can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement apparatus is used to measure the volume and number of toner particles using a 100 μm aperture as the aperture. The number distribution is calculated. At this time, the measured data is obtained in a channel obtained by dividing a particle size of 1.59 to 64.0 μm into 256 parts. The data obtained in 256Ch is processed in 16 divisions, and the weight-based weight average particle diameter D4 obtained from the volume distribution according to the present invention (the median value of each channel is the representative value for each channel), the number The number-based number average particle diameter D1 obtained from the distribution is obtained.

  Next, the frequency% A at the peak particle size D is calculated from the 256ch number-based particle size distribution (see FIG. 3) obtained using the above-mentioned Coulter Multisizer IIE (manufactured by Coulter).

  The particle size at which the frequency% A at the peak particle size D takes a half value A / 2 is calculated from the particle size distribution and is set as W1 and W2. At this time, it can obtain | require as half value width W = W2-W1.

  The toner used in the present invention preferably has an acid value of 0.5 to 20 mgKOH / g. By controlling the acid value of the toner within this range, for example, the affinity between the carboxyl group of the toner particle surface and the surface of the inorganic fine powder is improved, and the inorganic fine powder can be surely present on the surface of the toner particle. Become. As a result, it is easy to efficiently express the action of reducing the cohesive force between the toner particles in the compacted state at the contact portion between the transfer belt and the photoconductor, and the ease of releasing the toner layer compacted at the transfer nip is improved. Further, it is possible to prevent the transfer from being lost, and furthermore, since the inorganic fine powder can be present on the toner particle surface more uniformly and reliably, the generation of the reversal component can be suppressed, and the transfer belt can be prevented from being stained. When the acid value of the toner is less than 0.5 mgKOH / g, the affinity between the toner particle surface and the inorganic fine powder is decreased, so that the inorganic fine powder is easily detached from the toner particle surface. As a result, the effect of reducing the cohesive force between the toner particles in the compacted state at the contact portion between the transfer belt and the photosensitive member is reduced, and the ease of releasing the compacted toner layer at the transfer nip is deteriorated. Contamination control effect is also reduced. On the other hand, when the acid value exceeds 20 mgKOH / g, the affinity between the toner particle surface and the inorganic fine powder becomes too large, and conversely, the cohesion between the toner particles may be increased. On the other hand, when the acid value exceeds 20 mgKOH / g, for example, when applied to a positively chargeable toner, the negative chargeability of the binder resin in the toner particles becomes strong, and the toner chargeability tends to be hindered.

  In the present invention, the acid value of the toner or binder resin can be determined as follows.

  The basic operation of measurement conforms to JIS K-0070.

  A sample 0.5 to 2.0 (g) is precisely weighed to obtain a sample weight W (g).

  A sample is put into a 300 (ml) beaker, and a mixed solution 150 (ml) of toluene / ethanol (4/1) is added and dissolved.

Titration using a 0.1N KOH methanol solution with a potentiometric titrator (eg, using a potentiometric titrator AT-400 (winworkstation) manufactured by Kyoto Electronics Co., Ltd. and an ABP-410 electric burette) Automatic titration is available.)
At this time, the usage amount of the KOH solution is S (ml), and at the same time, a blank is measured, and the usage amount of the KOH solution at this time is B (ml).

The acid value is calculated by the following formula. f is a factor of KOH.
Acid value (mgKOH / g) = ((SB) × f × 5.61) / W

  The toner used in the present invention has a THF-insoluble content of the binder resin component of 0.1 mass% to 50 mass%, preferably 10 mass% when extracted for 16 hours by Soxhlet extraction with tetrahydrafuran (THF). It is good to contain -50 mass%, More preferably, it contains 20 mass%-50 mass%.

  The THF-insoluble matter functions to maintain the durability of the toner, and is important for improving the mechanical durability of the toner that is exposed to the compaction state at the contact area between the transfer belt and the photoreceptor continuously at a high speed for a long period of time. It is. When the THF-insoluble content of the binder resin component when extracted for 16 hours exceeds 50% by mass, the dispersibility of the raw material in the toner particles tends to deteriorate, and the toner chargeability tends to become non-uniform. May increase the cohesion between particles.

  In the present invention, the THF-insoluble content of the binder resin component can be determined as follows.

About 1.0 g of the binder resin is weighed (W1 g), placed in a cylindrical filter paper (for example, No. 86R size 28 × 100 mm, manufactured by Toyo Filter Paper Co., Ltd.), subjected to a Soxhlet extractor and extracted for 16 hours using 200 ml of THF as a solvent. At this time, the extraction is performed at a reflux rate such that the solvent extraction cycle is about once every 4 to 5 minutes. After the extraction is completed, the cylindrical filter paper is taken out and vacuum-dried at 40 ° C. for 8 hours, and the extraction residue is weighed (W2 g). Next, the weight of incinerated residual ash in the toner is determined (W3 g). The incineration residual ash content is obtained by the following procedure. About 2 g of a sample is placed in a 30 ml magnetic crucible that has been precisely weighed in advance, and weighed accurately, and the mass (Wag) of the sample is precisely weighed. The crucible is put in an electric furnace, heated at about 900 ° C. for about 3 hours, allowed to cool in the electric furnace, and allowed to cool in a desiccator for 1 hour or more at room temperature, and the mass of the crucible is precisely weighed. The incineration residual ash content (Wbg) is obtained from here.
Incineration residual ash content (mass%) = (Wb / Wa) × 100

  The mass (W3g) of the incinerated residual ash content of the sample is determined from this content rate.

The THF-insoluble content can be obtained from the following formula.
THF-insoluble matter = [W2-W3] / [W1-W3] × 100%

In addition, the measurement of the THF-insoluble content of the sample not containing any component other than the resin such as the binder resin was performed by obtaining the extraction residue (W2g) in the same process as described above for the resin weighed in a predetermined amount (W1g). Desired.
THF insoluble matter = W2 / W1 × 100 (%)

  Further, the toner used in the present invention has a molecular weight distribution by THF-soluble GPC and has at least one peak in a molecular weight region of 3,000 to 30,000, and a peak area having a molecular weight of 100,000 or less. What is 70-100 mass% with respect to a peak area is preferable.

  By having at least one peak in the molecular weight region of 3,000 to 30,000, the dispersibility of the raw material in the toner becomes good. As a result, the toner chargeability becomes uniform, and the effect of alleviating the cohesive force between the toner particles at the contact portion between the transfer belt and the photosensitive member is easily exhibited effectively. When the molecular weight peak is less than 3,000, not only the storage stability of the toner is lowered but also the mechanical durability of the toner is lowered, so that the toner is easily packed at the contact portion between the transfer belt and the photoreceptor. Therefore, transfer loss is likely to occur. When the molecular weight peak exceeds 30,000, it becomes difficult to disperse the raw materials during the production of the toner particles, and the toner chargeability becomes non-uniform. Therefore, the cohesive force between the toner particles at the contact portion between the transfer belt and the photoconductor. Increases and the inversion component increases. When the peak area with a molecular weight of 100,000 or less is less than 70% of the total peak area, there is little influence on the effect of preventing transfer dropout and the effect of suppressing contamination of the transfer belt itself, but sufficient fixing during high-speed printing. It becomes difficult to maintain sex.

  In the present invention, the measurement of the molecular weight distribution by GPC of the THF soluble part of the toner can be obtained as follows.

The column is stabilized in a heat chamber at 40 ° C., THF is flowed through the column at this temperature as a solvent at a flow rate of 1 ml / min, and about 100 μl of THF sample solution is injected and measured. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value and the count value of a calibration curve prepared from several types of monodisperse polystyrene standard samples. As a standard polystyrene sample for preparing a calibration curve, for example, a standard polystyrene sample having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko KK is suitably used. The detector uses an RI (refractive index) detector. In addition, it is preferable to combine a plurality of commercially available polystyrene gel columns as the column. of _{TSKgel G1000H (H XL), G2000H} (H XL), G3000H (H XL), G4000H (H XL), G5000H (H XL), G6000H (H XL), G7000H (H XL), include a combination of TSKgurd column be able to.

  Moreover, a sample is produced as follows.

  Place the sample in THF and let stand for several hours, then shake well and mix well with THF (until the sample is no longer united) and let stand for more than 12 hours. At that time, the standing time in THF should be 24 hours or more. After that, a sample processed filter (pore size 0.2 to 0.5 μm, for example, Mysori Disc H-25-2 (manufactured by Tosoh Corporation) can be used) is used as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

  In the present invention, the types of binder resins contained in the toner particles include styrene resins, styrene copolymer resins, polyester resins, polyol resins, polyvinyl chloride resins, phenol resins, naturally modified phenol resins, and natural resin modified resins. Examples thereof include maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, and petroleum resin.

  The binder resin contained in the toner particles used in the present invention is a styrenic polymer because it is preferable to apply a positively chargeable toner and the affinity with the inorganic fine powder can be easily controlled. Is preferred. Furthermore, the styrenic polymer may be a mixture or a reaction product of a carboxyl group-containing vinyl resin and a glycidyl group-containing vinyl resin.

  As a comonomer for the styrene monomer of the styrene copolymer, styrene derivatives such as vinyltoluene, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, acrylic Acrylic acid ester such as phenyl acid; Methacrylic acid ester such as methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate; Maleic acid; Double such as butyl maleate, methyl maleate, dimethyl maleate Dicarboxylic acid ester having a bond; acrylamide, acrylonitrile, methacrylonitrile, butadiene; vinyl chloride; vinyl ester such as vinyl acetate and vinyl benzoate; ethylene, propylene, butylene Such ethylenic olefins, vinyl methyl ketone, such as vinyl vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl propionate ether. These vinyl monomers are used alone or in combination of two or more.

  The binder resin contained in the toner particles used in the present invention preferably has an acid value in the range of 0.5 to 20 mg KOH / g. Particularly preferably, it has an acid value of 0.5 to 15 mgKOH / g. When the acid value of the binder resin is within the above range, for example, the affinity between the carboxyl group on the toner particle surface and the surface of the inorganic fine powder is improved, and the inorganic fine powder can be surely present on the toner particle surface. It becomes. As a result, it becomes easy to efficiently express the action of reducing the cohesive force between the toner particles in the compacted state at the contact portion between the transfer belt and the photosensitive member, and the toner layer in the compacted state at the transfer nip portion can be easily released. In addition, it is possible to prevent the transfer from falling out, and furthermore, since the inorganic fine powder can be present more uniformly and reliably on the surface of the toner particles, the generation of the reversal component can be suppressed, and the transfer belt can be prevented from being stained. When the acid value is less than 0.5 mgKOH / g, the affinity between the toner particle surface and the inorganic fine powder is decreased, so that the inorganic fine powder is easily detached from the toner particle surface. As a result, the effect of alleviating the cohesive force between the toner particles is reduced, the ease of unraveling of the toner layer that has become compacted at the transfer nip portion is deteriorated, and the effect of suppressing transfer belt contamination is also reduced. On the other hand, when the acid value exceeds 20 mgKOH / g, the affinity between the toner particle surface and the inorganic fine powder becomes too large, and conversely, the cohesion between the toner particles may be increased. On the other hand, when the acid value exceeds 20 mgKOH / g, for example, when applied to a positively chargeable toner, the negative chargeability of the binder resin in the toner particles becomes strong, and the toner chargeability tends to be hindered.

  Examples of the monomer for adjusting the acid value of the binder resin include acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, cinnamic acid, vinyl acetic acid, isocrotonic acid, and angelic acid, and α- β-alkyl derivatives, fumaric acid, maleic acid, citraconic acid, alkenyl succinic acid, itaconic acid, mesaconic acid, dimethyl maleic acid, dimethyl fumaric acid and other unsaturated dicarboxylic acids and monoester derivatives or anhydrides thereof, etc. Such a monomer can be made alone or mixed and copolymerized with other monomers to produce a desired polymer. Among these, it is particularly preferable to use a monoester derivative of an unsaturated dicarboxylic acid in order to control the acid value.

  More specifically, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate, monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monophenyl fumarate Monoesters of α, β-unsaturated dicarboxylic acids such as: monobutyl n-butenyl succinate, monomethyl n-octenyl succinate, monoethyl n-butenylmalonate, monomethyl n-dodecenyl glutarate, monobutyl n-butenyl adipate And monoesters of alkenyldicarboxylic acid such as

  The carboxyl group-containing monomer as described above may be added in an amount of 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, with respect to 100 parts by mass of all monomers constituting the binder resin.

  Examples of a polymerization method that can be used in the present invention as a method for synthesizing the binder resin of the present invention include a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.

  Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase with an emulsifier, and polymerization is performed using a water-soluble polymerization initiator. In this method, the reaction heat can be easily adjusted, and the termination reaction rate is low because the phase in which the polymerization is carried out (the oil phase consisting of the polymer and the monomer) and the aqueous phase are separate, resulting in a high polymerization rate. A product having a high degree of polymerization is obtained. Furthermore, the reason is that the polymerization process is relatively simple, and that the polymerization product is fine particles, so that it can be easily mixed with colorants, charge control agents and other additives in the production of toner. Therefore, there is an advantage as a method for producing a binder resin for toner.

  However, the added polymer is likely to be impure due to the added emulsifier, and an operation such as salting out is necessary to take out the polymer. Suspension polymerization is convenient to avoid this inconvenience.

  In suspension polymerization, it is good to carry out by 100 mass parts or less (preferably 10-90 mass parts) of monomers with respect to 100 mass parts of aqueous solvents. Examples of the dispersant that can be used include polyvinyl alcohol, partially saponified polyvinyl alcohol, calcium phosphate, and the like, and generally 0.05 to 1 part by mass with respect to 100 parts by mass of the aqueous solvent. The polymerization temperature is suitably 50 to 95 ° C., but is appropriately selected depending on the initiator used and the target polymer.

  The binder resin contained in the toner particles used in the present invention is preferably produced by using a polyfunctional polymerization initiator alone or in combination with a monofunctional polymerization initiator as exemplified below.

  Specific examples of the polyfunctional polymerization initiator having a polyfunctional structure include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxy Isopropyl) benzene, 2,5-dimethyl-2,5- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, tris- (t-butyl) Peroxy) triazine, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 4,4-di-t-butylperoxyvaleric acid-n-butyl ester , Di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, di-t-butylperoxytrimethyladipate, 2,2-bis- ( , 4-di-t-butylperoxycyclohexyl) propane, 2,2-t-butylperoxyoctane and various polymer oxides, etc., a functional group having a polymerization initiating function such as two or more peroxide groups in one molecule. And a polyfunctional polymerization initiator having a peroxide group in one molecule such as diallyl peroxydicarbonate, t-butylperoxymaleic acid, t-butylperoxyallylcarbonate and t-butylperoxyisopropyl fumarate And a polyfunctional polymerization initiator having both a functional group having a polymerization initiating function and a polymerizable unsaturated group.

  Of these, more preferred are 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, di-t-butylperoxy. Hexahydroterephthalate, di-t-butylperoxyazelate and 2,2-bis- (4,4-di-t-butylperoxycyclohexyl) propane, and t-butylperoxyallyl carbonate.

  These polyfunctional polymerization initiators are preferably used in combination with a monofunctional polymerization initiator in order to satisfy various performances required as a binder for toner. In particular, it is preferable to use in combination with a polymerization initiator having a decomposition temperature of a half-life of 10 hours which is lower than the decomposition temperature for obtaining a half-life of 10 hours of the polyfunctional polymerization initiator.

  Specifically, benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (t-butylperoxy) valerate, dichroic Organic peroxides such as milperoxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t-butylperoxide, azobisisobutyronitrile, diazoamino Examples include azo and diazo compounds such as azobenzene.

  These monofunctional polymerization initiators may be added to the monomer at the same time as the polyfunctional polymerization initiator, but in order to keep the efficiency of the polyfunctional polymerization initiator appropriate, in the polymerization step, It is preferably added after the half-life indicated by the polyfunctional polymerization initiator has elapsed.

  These initiators are preferably used in an amount of 0.05 to 2 parts by mass with respect to 100 parts by mass of the monomer from the viewpoint of efficiency.

  It is also preferable that the binder resin is crosslinked with a crosslinking monomer.

  As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used. Specific examples include aromatic divinyl compounds (eg, divinylbenzene, divinylnaphthalene, etc.); diacrylate compounds linked by alkyl chains (eg, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4 -Butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); alkyl chain containing an ether bond Diacrylate compounds (eg, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, Ethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds in place of methacrylate); diacrylate compounds linked by a chain containing an aromatic group and an ether bond (eg, polyoxyethylene) (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate, and methacrylates of the above compounds Furthermore, polyester-type diacrylate compounds (for example, trade name MANDA (Nippon Kayaku)) are mentioned. As polyfunctional crosslinking agents, pentaerythritol acrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and acrylates of the above compounds are replaced with methacrylate. Triallyl cyanurate, triallyl trimellitate; and the like.

  These crosslinking agents are preferably used in the range of 0.00001 to 1 part by mass, preferably 0.001 to 0.05 part by mass, with respect to 100 parts by mass of the other monomer components.

  Among these crosslinkable monomers, aromatic divinyl compounds (especially divinylbenzene), diethers linked by a chain containing an aromatic group and an ether bond are preferably used from the viewpoint of toner fixing properties and offset resistance. Examples include acrylate compounds.

  As other synthesis methods, a bulk polymerization method and a solution polymerization method can be used. However, in the bulk polymerization method, a polymer having a low molecular weight can be obtained by polymerizing at a high temperature to increase the termination reaction rate, but there is a problem that the reaction is difficult to control. In that respect, the solution polymerization method can easily obtain a polymer with a desired molecular weight under mild conditions by utilizing the difference in chain transfer of radicals by a solvent and adjusting the amount of initiator and reaction temperature. Is preferable. In particular, a solution polymerization method under a pressurized condition is also preferable in that the amount of the initiator used is minimized and the influence of the remaining initiator is minimized.

  The composition of the polyester resin contained in the toner particles used in the present invention is as follows.

  Examples of the divalent alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1, 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and bisphenol represented by the formula (E) and derivatives thereof;

（式中Ｒはエチレンまたはプロピレン基であり、ｘ，ｙはそれぞれ０以上の整数であり、かつ、ｘ＋ｙの平均値は０〜１０である。）

(In the formula, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 to 10.)

  And diols represented by the formula (F);

  Examples of the divalent acid component include benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof, lower alkyl esters; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid. Acids or anhydrides thereof, lower alkyl esters; alkenyl succinic acids or alkyl succinic acids such as n-dodecenyl succinic acid and n-dodecyl succinic acid, or anhydrides, lower alkyl esters thereof; fumaric acid, maleic acid, citraconic acid, itaconic acid Dicarboxylic acids such as unsaturated dicarboxylic acids or anhydrides thereof, lower alkyl esters;

  Moreover, it is preferable to use together the trihydric or more alcohol component and trivalent or more acid component which work as a crosslinking component.

  Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene, etc. Is mentioned.

  Examples of the trivalent or higher polycarboxylic acid component in the present invention include trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5, 7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene Carboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empole trimer acid, and their anhydrides, lower alkyl esters;

（式中Ｘは炭素数３以上の側鎖を１個以上有する炭素数５〜３０のアルキレン基又はアルケニレン基）
で表わされるテトラカルボン酸等、及びこれらの無水物、低級アルキルエステル等の多価カルボン酸類及びその誘導体が挙げられる。

(Wherein X is an alkylene group or alkenylene group having 5 to 30 carbon atoms having one or more side chains having 3 or more carbon atoms)
And polycarboxylic acids such as anhydrides and lower alkyl esters thereof and derivatives thereof.

  The alcohol component used in the present invention is 40 to 60 mol%, preferably 45 to 55 mol%, and the acid component is 60 to 40 mol%, preferably 55 to 45 mol%. Moreover, it is preferable that the polyvalent component more than trivalence is 5-60 mol% in all the components.

  The polyester resin can also be obtained by a generally known condensation polymerization.

  In the present invention, the toner particles can contain a charge control agent, whereby positive chargeability or negative chargeability can be maintained, and the chargeability can be controlled.

  The following substances are used for controlling the toner to be positively charged. For example, modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs of phosphonium salts thereof. Onium salts and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide) Metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexane Such diorgano tin borate such Rusuzuboreto; guanidine compounds, imidazole compounds. These can be used alone or in combination of two or more. In the present invention, among these, a triphenylmethane compound and a quaternary ammonium salt whose counter ion is not halogen are particularly preferably used. When these are used, generation of a toner reversal component can be further suppressed, and transfer Belt contamination can be reduced.

  Further, there are the following substances that control the toner to be negatively charged. For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acid metal complexes, and aromatic dicarboxylic acid metal complexes. Other examples of controlling the toner to be negatively charged include aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids and aromatic polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol. .

  As a method for incorporating the charge control agent into the toner, there are a method of adding it inside the toner particles and a method of adding it externally, and either method may be used. The amount of these charge control agents used is determined by the toner production method including the type of binder resin, the presence or absence of other additives, and the dispersion method, and is not uniquely determined. It is used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin.

  In the present invention, the toner particles can contain a colorant, and examples of the colorant include any suitable pigment or dye. Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary to maintain the optical density of the fixed image, and the amount varies depending on the type of pigment, but is 0.1 to 20 parts by mass, preferably 0.2 to 100 parts by mass of the binder resin. An addition amount of -10 parts by weight is used.

  Further, a dye is further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and the amount used varies depending on the type of the dye, but is 0.1 to 20 parts by weight, preferably 0, based on 100 parts by weight of the binder resin. The addition amount of 3 to 10 parts by mass is good.

  The toner used in the present invention preferably contains the following waxes in order to provide releasability. The waxes used in the present invention include the following. For example, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidation of aliphatic hydrocarbon wax such as oxidized polyethylene wax Or block copolymers thereof; plant waxes such as candelilla wax, carnauba wax, wax wax, jojoba wax; animal waxes such as beeswax, lanolin, whale wax; minerals such as ozokerite, ceresin, petrolactam Waxes based on fatty acid esters such as montanic acid ester wax and caster wax; those obtained by partially or fully deoxidizing fatty acid esters such as deoxidized carnauba wax That. Further, a saturated straight chain such as palmitic acid, stearic acid, montanic acid, or a long-chain alkyl carboxylic acid having a long-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; stearyl alcohol; Saturated alcohols such as eicosyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long chain alkyl alcohols having a long chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid amide, oleic acid amide An aliphatic amide such as lauric acid amide; a saturated fatty acid bisamide such as methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide; Unsaturated fatty acid amides such as oleic acid amide, hexamethylenebisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, N, Aromatic bisamides such as N'-distearylisophthalamide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap); aliphatic hydrocarbon waxes Wax grafted with vinyl monomers such as styrene and acrylic acid; partially esterified product of fatty acid and polyhydric alcohol such as behenic acid monoglyceride; methyl having hydroxyl group obtained by hydrogenating vegetable oil Ester compound And the like.

  Preferred waxes include polyolefins obtained by radical polymerization of olefins under high pressure; polyolefins obtained by purifying low molecular weight by-products obtained during polymerization of high molecular weight polyolefins; polymerized using catalysts such as Ziegler catalysts and metallocene catalysts under low pressures Polyolefins; polyolefins polymerized using radiation, electromagnetic waves or light; low molecular weight polyolefins obtained by thermally decomposing high molecular weight polyolefins; paraffin wax, microcrystalline wax, Fuchsia-Tropsch wax; Jindole method, hydrocol method, age method Synthetic hydrocarbon waxes synthesized by, etc .; synthetic waxes using a compound having one carbon atom as a monomer, hydrocarbon waxes having a functional group such as a hydroxyl group or a carboxyl group; hydrocarbon waxes having a functional group That a mixture of waxes; styrene these waxes as a matrix, maleic acid ester, acrylate, methacrylate, wax graft-modified with such vinyl monomers of maleic acid.

  In addition, these waxes have a sharp molecular weight distribution using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method or a melt liquid crystal method, low molecular weight solid fatty acids, low molecular weight solids. An alcohol, a low molecular weight solid compound, and other impurities are preferably used.

  Moreover, the addition amount of the wax is preferably 0.1 to 20 parts by mass, and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the binder resin. Two or more kinds of waxes may be used in combination.

  The endothermic curve measured by DSC of the toner to which these waxes are added preferably has a maximum peak in the region of 60 to 120 ° C.

  When having the maximum peak in these ranges, the fixability and offset resistance are good. When the temperature is lower than 60 ° C., the preservability of the developer itself deteriorates due to the plasticizing effect of the wax. When it exceeds 120 ° C., the fixing property is deteriorated.

  Further, in the toner used in the present invention, it is preferable to add a silica fine powder in order to improve charging stability, developability, fluidity and durability. In the present invention, the inorganic fine powder is further added to the toner by adding together the inorganic fine powder and a silica fine powder having a high fluidity-imparting ability to the toner particle surface and a smaller number average particle size of the primary particles. It was found that it was possible to disperse uniformly. By adding silica having a smaller number average particle diameter, the toner cohesiveness mitigating effect expressed in combination with inorganic fine powder may be slightly reduced, but in the present invention, by using silica together, Since the inorganic fine powder is more uniformly dispersed and adhered to the surface of the toner particles, it is preferable because the effect of alleviating the toner cohesive force at the transfer nip is expressed more effectively. When inorganic fine powder is not uniformly dispersed, the effect of relaxing the cohesive force between the toner particles acting on the toner layer that has become compacted in the transfer nip is biased, and a print image can be obtained continuously at high speed for a long period of time. Below, there is a case where the effect of preventing the transfer omission is reduced.

As the silica fine powder, both the so-called dry method produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass or the like can be used. as having less silanol groups on the inner surface and the silica fine powder, also Na ₂ O, SO ₃ ^- it is preferable less dry silica of manufacturing residue such. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. Is also included.

  In the present invention, the silica fine powder is preferably hydrophobized. By hydrophobizing the silica fine powder, it prevents the silica fine powder from lowering the chargeability in a high humidity environment and improves the environmental stability of the triboelectric charge amount of the toner particles adhered to the surface of the silica fine powder. Further, it is possible to further improve the environmental stability of development characteristics such as image density and fog as a toner. In the present invention, the silica fine powder has a methanol concentration within a range of 65 to 80% by volume when the transmittance is 80% when the wettability with respect to the methanol / water mixed solvent is measured by the transmittance of light having a wavelength of 780 nm. Preferably there is.

  If the methanol concentration when the transmittance is 80% exceeds 80% by volume, this indicates that the amount of silica fine powder attached is too large, or the degree of embedding in the toner surface is too small. Charging performance is impaired, which is not preferable. Furthermore, since the amount of silica fine powder interposed between the toner particle surface and the inorganic fine powder is increased, the effect of reducing the cohesive force between the toner particles is reduced. Further, when the methanol concentration at a transmittance of 80% is lower than 65% by volume, it indicates that the amount of silica fine powder adhering to the toner particle surface is small or the degree of embedding in the toner surface is large. In such a case, it is difficult to maintain the charge amount, and it is difficult to obtain good developability. Further, since the amount of the fine silica powder is small, the dispersibility of the inorganic fine powder on the surface of the toner particles is deteriorated, and the effect of reducing the cohesive force between particles is reduced.

  In the present invention, the relationship between the transmittance and the methanol concentration, that is, the wettability of silica, that is, the hydrophobic property of silica is measured using a methanol dropping transmittance curve. Specifically, as the measuring device, for example, a powder wettability tester WET-100P manufactured by Reska Co., Ltd. may be mentioned, and specific measuring operations may include the methods exemplified below.

  First, 70 ml of a hydrated methanol solution composed of 60% by volume of methanol and 40% by volume of water is placed in a container, and dispersed for 5 minutes with an ultrasonic disperser in order to remove bubbles and the like in the measurement sample. A sample liquid for measuring the hydrophobic property of the toner is prepared by precisely adding 0.5 g of silica as a specimen to the sample.

Next, while stirring the measurement sample solution at a rate of 6.67s ^-1, methanol 1.3 ml / min. Are added continuously at a dropping speed of, and the transmittance is measured with light having a wavelength of 780 nm to prepare a methanol dropping transmittance curve. In this measurement, a glass flask having a diameter of 5 cm and a thickness of 1.75 mm was used as the flask, and a magnetic stirrer having a spindle shape of 25 mm in length and a maximum diameter of 8 mm and coated with fluororesin. What was done was used.

  As treatment agents for hydrophobization treatment, treatment agents such as silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane compounds, silane coupling agents, other organic silicon compounds, and organic titanium compounds may be used alone or in combination. And may be processed. Of these, treatment with a silane compound having a substituent containing nitrogen and silicone oil is particularly preferred from the standpoint of chargeability.

  However, the silane compound having a substituent having a nitrogen element greatly contributes to imparting positive chargeability to the silica fine powder. When the treatment amount is large, the positive chargeability becomes strong, but the hydrophilicity of the amino group. This increases the hygroscopicity. Therefore, when using a silane compound, it is preferable to treat in combination with silicone oil. The treatment can be performed according to a known method.

  Other external additives may be added to the toner used in the present invention as necessary.

  Examples thereof include resin fine particles and inorganic fine particles that function as a charging aid, a conductivity imparting agent, a fluidity imparting agent, an anti-caking agent, a release agent at the time of fixing with a heat roller, a lubricant, an abrasive, and the like.

  For example, examples of the lubricant include polyethylene fluoride powder, zinc stearate powder, polyvinylidene fluoride powder, and the like. Among these, polyvinylidene fluoride powder is preferable. Examples of the abrasive include cerium oxide powder, silicon carbide powder, and strontium titanate powder. Of these, strontium titanate powder is preferable. In particular, when a photoconductor having a photoconductive layer containing amorphous silicon and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride is used as the photoconductor, the cleaning property of the photoconductor surface is improved. However, in the present invention, strontium titanate is particularly preferable in that it is difficult to inhibit the toner cohesive force mitigating effect at the contact portion between the transfer belt and the photosensitive member.

  As described above, according to the present invention, by controlling the relationship between the toner particles containing at least the binder resin and the colorant and the inorganic fine powder, or by controlling the relationship between other toner constituent materials, It is possible to easily control the cohesive force between toner particles, and to obtain an image forming system capable of preventing transfer loss and suppressing transfer belt contamination even when a print image is obtained continuously at a high speed for a long period of time. I can do it.

  In the present invention, the toner can be produced according to any known toner production method. For example, a binder resin, a colorant, other additives, etc. are sufficiently mixed by a mixer such as a Henschel mixer and a ball mill, and then melt-kneaded using a heat kneader such as a heating roll, a kneader, an extruder, After cooling and solidification, pulverization and classification are performed, and if necessary, desired additives are sufficiently mixed by a mixer such as a Henschel mixer to obtain the toner of the present invention.

  For example, as a mixer, Henschel mixer (made by Mitsui Mining); Super mixer (made by Kawata); Ribocorn (made by Okawara Seisakusho); Nauter mixer, turbulizer, cyclomix (made by Hosokawa Micron); Spiral pin mixer 1 (manufactured by Taiheiyo Kiko Co., Ltd.); Laedige mixer (manufactured by Matsubo Co., Ltd.), and as a kneading machine, KRC kneader (manufactured by Kurimoto Iron Works Co., Ltd.); bus co kneader (manufactured by Buss Co.); Machine (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Works); PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); MS type pressure kneader, Nider Ruder (Moriyama Seisakusho); Banbury mixer (Kobe Steel Works) As a pulverizer, a counter jet mill, a micron jet, an inomizer (manufactured by Hosokawa Micron Co.); an IDS type mill, a PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.); a cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); URMAX (manufactured by Nisso Engineering Co., Ltd.); SK Jet O-Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turboe Co., Ltd.); Examples of classifiers include: class seal, micron classifier, specick classifier (manufactured by Seishin Enterprise Co., Ltd.); turbo classifier (manufactured by Nissin Engineering Co., Ltd.); micron separator, turboplex (ATP), TSP separator (Hosokawa micron) (Made by company) Elbow Jet (manufactured by Nippon Steel & Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Engineering Co., Ltd.); YM Micro Cut (manufactured by Yaskawa Shoji Co., Ltd.) can be mentioned. Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (Tokuju Kosakusha Co., Ltd.); Vibrasonic System (manufactured by Dalton Co.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Micro shifter (manufactured by Hadano Sangyo Co., Ltd.), circular vibrating sieve, etc.

  Hereinafter, the present invention will be described based on specific examples. However, this does not limit the embodiment of the present invention.

<Example of production of low molecular weight component (B-1)>
Into a four-necked flask, 300 parts by mass of xylene is charged, and the inside of the container is sufficiently replaced with nitrogen while stirring, and then heated to reflux. Under this reflux, a mixture of 76 parts by mass of styrene, 24 parts by mass of acrylate-n-butyl and 2 parts by mass of di-tert-butyl peroxide (initiator 1) was added dropwise over 4 hours, and then maintained for 2 hours. The polymerization was completed, and a low molecular weight polymer solution (B-1) was obtained.

<Production example of low molecular weight component (B-2)>
Polymerization is carried out in the same manner as in the production example of the low molecular weight component B-1 using 77 parts by mass of styrene, 23 parts by mass of acrylic acid-n-butyl, and 2.5 parts by mass of the initiator 1, and the low molecular weight polymer solution B-2 Got.

<Example of production of low molecular weight component (B-3)>
Polymerization is carried out in the same manner as in the production example of the low molecular weight component B-1 using 73 parts by mass of styrene, 23 parts by mass of acrylic acid-n-butyl, 4 parts by mass of monobutyl maleate, and 2.5 parts by mass of initiator 1, and low A molecular weight polymer solution B-3 was obtained.

<Production example of high molecular weight component (A-1)>
After adding 180 parts by weight of debasic water and 20 parts by weight of a 2% by weight aqueous solution of polyvinyl alcohol in a four-necked flask, 71 parts by weight of styrene, 24 parts by weight of acrylic acid-n-butyl, 5 parts by weight of monobutyl maleate, Add 0.005 parts by weight of divinylbenzene and 0.1 part by weight of 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane (half-life 10 hours temperature; 92 ° C.), Stir to make a suspension.

  After sufficiently replacing the inside of the flask with nitrogen, the temperature was raised to 85 ° C. to initiate polymerization. After maintaining at the same temperature for 24 hours, 0.1 part by mass of benzoyl peroxide (half-life 10 hours temperature; 72 ° C.) was added. Furthermore, the polymerization was completed by maintaining for 12 hours. Thereafter, the high molecular weight polymer was separated by filtration, washed with water and dried to obtain a high molecular weight component (A-1).

<Production example of high molecular weight component (A-2)>
70 parts by mass of styrene, 27 parts by mass of acrylate-n-butyl, 3 parts by mass of monobutyl maleate, 0.005 parts by mass of divinylbenzene and 1 part by mass of initiator 2 as in the production example of the high molecular weight component (A-1) Part was used to obtain a high molecular weight component (A-2).

<Production example of high molecular weight component (A-3)>
Into a four-necked flask, 300 parts by mass of xylene is charged, and the inside of the container is sufficiently replaced with nitrogen while stirring, and then heated to reflux. Under this reflux, first, 81 parts by weight of styrene, 15 parts by weight of acrylic acid-n-butyl and 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane (initiator 2, half-life 10 (Time temperature: 92 ° C.) 0.8 parts by mass of the mixed solution is dropped over 4 hours. When these mixed liquids are dropped for 2 hours, a mixed liquid of 4 parts by weight of methacrylic acid and 20.2 parts by weight of an initiator is dropped over 2 hours. After all was dropped, the polymerization was completed by maintaining for 2 hours to obtain a high molecular weight component (A-3) solution.

<Example of production of binder resin (C-1)>
In a four-necked flask, 200 parts by mass of a xylene solution of the low molecular weight component (B-2) (corresponding to 60 parts by mass of the low molecular weight component) is added, and the temperature is raised and stirred under reflux. On the other hand, 200 parts by mass of the high molecular weight component (A-3) solution (equivalent to 40 parts by mass of the high molecular weight component) is charged into a separate container and refluxed. After the low molecular weight component (B-2) solution and the high molecular weight component (A-3) solution are mixed under reflux, the organic solvent is distilled off, and the resulting resin is cooled, solidified and then pulverized to obtain a resin (C -1) was obtained.

  The acid value, peak molecular weight and other results are shown in Table 1.

<Example of production of binder resin (C-2)>
In a four-necked flask, 200 parts by mass of the xylene solution of the low molecular weight component (B-1) (equivalent to 70 parts by mass of the low molecular weight component) is added, and the temperature is raised and stirred under reflux. Into the flask, 30 parts by mass of the high molecular weight component (A-2) is charged and refluxed. After the low molecular weight component (B-1) solution and the high molecular weight component (A-2) are mixed under reflux, the organic solvent is distilled off, and the resulting resin is cooled, solidified and pulverized to obtain a resin (C- 2) was obtained.

  The acid value, peak molecular weight and other results are shown in Table 1.

<Example of production of binder resin (C-3)>
In a four-necked flask, 200 parts by mass of the xylene solution of the low molecular weight component (B-1) (equivalent to 80 parts by mass of the low molecular weight component) is charged, heated up and stirred under reflux. Into the flask, 20 parts by mass of the high molecular weight component (A-1) is charged and refluxed. After the low molecular weight component (B-1) solution and the high molecular weight component (A-1) are mixed under reflux, the organic solvent is distilled off, and the resulting resin is cooled, solidified and pulverized to obtain a resin (C- 3) was obtained.

  The acid value, peak molecular weight and other results are shown in Table 1.

<Example of production of binder resin (C-4)>
In a four-necked flask, 200 parts by mass of a xylene solution of the low molecular weight component (B-3) (corresponding to 70 parts by mass of the low molecular weight component) is added, and the temperature is raised and stirred under reflux. Into the flask, 30 parts by mass of the high molecular weight component (A-1) is charged and refluxed. After the low molecular weight component (B-3) solution and the high molecular weight component (A-1) are mixed under reflux, the organic solvent is distilled off, and the resulting resin is cooled, solidified and pulverized to obtain a resin (C- 4) was obtained.

  The acid value, peak molecular weight and other results are shown in Table 1.

<Production Example of Toner 1>
Binder resin C-1 100 parts by mass Magnetic iron oxide particles (octahedron) 90 parts by mass Fischer-Tropsch wax b (melting point: 101 ° C.) 4 parts by mass Charge control agent A (triphenylmethane lake pigment below) 2 Parts by mass

  The above materials were premixed with a Henschel mixer and then melt kneaded with a biaxial kneading extruder. The obtained kneaded product is cooled, coarsely pulverized with a hammer mill, then pulverized with a fine pulverizer using a jet stream, and the resulting finely pulverized powder is classified using a multi-division classifier utilizing the Coanda effect. Toner particles were obtained. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 42 mV.

With respect to 100 parts by mass of the toner particles, 0.1 part by mass of alumina particles (zeta potential at pH = 4, 36.5 mV, specific surface area: 100 m ^{2 /} g) as an inorganic fine powder, and amino-modified silicone oil (amino Equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) 0.8 parts by mass of strontium titanate (0.8 parts by mass of hydrophobic silica fine powder a having a methanol concentration of 75% when treated with 17 parts by mass of 80% transmittance) Toner 1 was obtained by adding 3.0 parts by mass of a primary particle size of 1.5 μm, and externally adding and mixing with a Henschel mixer under arbitrary conditions, and sieving with a mesh having an aperture of 150 μm. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 2>
In the production example of the toner 1, the addition amount of the alumina particles added as the inorganic fine powder is changed to 0.2 part, and 3.0 parts by mass of strontium titanate (primary particle diameter 1.5 μm) is not added. In the same manner, Toner 2 was obtained. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 3>
In the toner 1 production example, the alumina particles added as inorganic fine powder were changed to 0.2 parts by mass of magnesium oxide particles (zeta potential at pH = 4: 44.3 mV, specific surface area: 5.3 m ^{2 /} g). A toner 3 was obtained in the same manner except that. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 4>
In the production example of the toner 1, except that alumina particles added as inorganic fine powder are changed to 0.2 parts by mass of zinc oxide particles (zeta potential at pH = 4: 8.3 mV, specific surface area: 30 m ^{2 /} g). Obtained toner 3 in the same manner. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 5>
Binder resin C-3 100 parts by mass Magnetic iron oxide particles (binuclear shape) 90 parts by mass Higher alcohol wax c (melting point: 100 ° C.) 4 parts by mass Charge control agent B (quaternary ammonium salt compound below) 2 Parts by mass

Toner particles were obtained in the same manner as in the production example of toner 1 except that the raw material of the toner particles was changed to the above. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 39.9 mV. To 100 parts by mass of the toner particles, 0.5 parts by mass of zinc oxide particles (zeta potential at pH = 4, 8.3 mV, specific surface area: 30 m ^{2 /} g) as an inorganic fine powder, and amino-modified silicone oil ( (Amino equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) Hydrophobic silica fine powder b having a methanol concentration of 69% at a transmittance of 80% treated simultaneously with 15 parts by mass and 2 parts by mass of aminosilane coupling agent Add 0.8 parts by mass and 3.0 parts by mass of strontium titanate (primary particle size 1.5 μm), externally add and mix using a Henschel mixer under any conditions, and sieve with a mesh having an opening of 150 μm. Got. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 6>
In the production example of the toner 5, the zinc oxide particles added as the inorganic fine powder are changed to 0.2 parts by mass of titanium oxide particles (zeta potential at pH = 4: 2.1 mV, specific surface area: 100 m ^{2 /} g). Except for the above, Toner 6 was obtained in the same manner. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 7>
Binder resin C-3 100 parts by mass Magnetic iron oxide particles (binuclear shape) 90 parts by mass Paraffin wax a (melting point: 75 ° C.) 4 parts by mass Charge control agent A (triphenylmethane lake pigment) 2 parts by mass Toner particles were obtained in the same manner as in the production example of toner 1 except that the raw material of the toner particles was changed to the above. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 40.5 mV. With respect to 100 parts by mass of the toner particles, alumina particles (zeta potential at pH = 4, 36.5 mV, specific surface area: 100 m ^{2 /} g) as inorganic fine powder, 0.5 parts by mass, amino-modified silicone oil (amino Equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) Hydrophobic silica fine powder b having a methanol concentration of 69% at a transmittance of 80% treated simultaneously with 15 parts by mass and 2 parts by mass of aminosilane coupling agent was reduced to 0 And 8 parts by mass and 3.0 parts by mass of strontium titanate (primary particle size 1.5 μm) are added and mixed under any conditions using a Henschel mixer, and sieved with a mesh having an aperture of 150 μm. Obtained. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 8>
Binder resin C-1 100 parts by mass Magnetic iron oxide particles (octahedral) 90 parts by mass Paraffin wax a (melting point: 75 ° C) 3 parts by mass Fischer-Tropsch wax b (melting point: 101 ° C) 2 parts by mass Charge control agent B (quaternary ammonium salt compound) 2 parts by mass Toner particles were obtained in the same manner as in the production example of toner 1 except that the raw material of the toner particles was changed to the above. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 41.2 mV. With respect to 100 parts by mass of the toner particles, zinc oxide particles (zeta potential at pH = 4: 8.3 mV, specific surface area: 300 m ^{2 /} g) as inorganic fine powders, 0.2 parts by mass, amino-modified silicone oil ( (Amino equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) Hydrophobic silica fine powder b having a methanol concentration of 69% at a transmittance of 80% treated simultaneously with 15 parts by mass and 2 parts by mass of aminosilane coupling agent 0.8 parts by mass and 3.0 parts by mass of strontium titanate (primary particle size 1.5 μm) are added and mixed externally under arbitrary conditions using a Henschel mixer, sieved with a mesh having an aperture of 150 μm, and toner 8 Got. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 9>
In the production example of Toner 1, inorganic fine powder was not added, and hydrophobic silica fine powder was prepared by adding 15 parts by mass of amino-modified silicone oil (amino equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) and aminosilane coupling agent 2 Toner 9 was obtained in the same manner except that the concentration of methanol was 69% hydrophobic silica fine powder b 0.8 parts by mass when the transmittance was 80% at the same time. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 10>
Binder resin C-4 100 parts by mass Magnetic iron oxide particles (octahedron) 90 parts by mass Paraffin wax a (melting point: 75 ° C.) 4 parts by mass Charge control agent B (quaternary ammonium salt compound) 2 parts by mass Toner particles were obtained in the same manner as in the production example of toner 1 except that the raw material of the toner particles was changed to the above. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 39.3 mV. With respect to 100 parts by mass of the toner particles, silica particles (zeta potential at pH = 4: -10. 3 mV, specific surface area: 30 m ^{2 /} g) as inorganic fine powder, 0.2 parts by mass, amino-modified silicone oil ( (Amino equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) Hydrophobic silica fine powder b having a methanol concentration of 69% at a transmittance of 80% treated simultaneously with 15 parts by mass and 2 parts by mass of aminosilane coupling agent 0.8 parts by mass and 3.0 parts by mass of strontium titanate (primary particle size 1.5 μm) are added and mixed externally using a Henschel mixer under a given condition, and sieved with a mesh having an aperture of 150 μm. Got. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 11>
Binder resin C-1 100 parts by mass Magnetic iron oxide particles (binuclear shape) 90 parts by mass Fischer-Tropsch wax b (melting point: 101 ° C.) 4 parts by mass Charge control agent A (triphenylmethane lake pigment) 2 parts by mass Part Toner particles were obtained in the same manner as in the production example of toner 1 except that the raw material of the toner particles was changed to the above. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 40.9 mV. With respect to 100 parts by mass of the toner particles, 0.2 part by mass of melamine resin particles (zeta potential at pH = 4, 3.2 mV, specific surface area: 50 m ^{2 /} g) as an inorganic fine powder, and amino-modified silicone oil ( (Amino equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) 0.8 parts by mass of strontium titanate and 0.8 parts by mass of hydrophobic silica fine powder a having a methanol concentration of 75% at a transmittance of 80% treated with 17 parts by mass Toner 11 was obtained by adding 3.0 parts by mass (primary particle size of 1.5 μm), externally mixing with a Henschel mixer under arbitrary conditions, and sieving with a mesh having an opening of 150 μm. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Toner 12>
-Binder resin C-2 100 parts by mass-Magnetic iron oxide particles (octahedral) 90 parts by mass-Higher alcohol wax c (melting point: 100 ° C) 4 parts by mass-Charge control agent C (nigrosine) 2 parts by mass Toner particles were obtained in the same manner as in Production Example of Toner 1 except that the raw materials were changed to those described above. When the zeta potential of the toner particles was measured, the pH of the supernatant was 4 and the zeta potential was 32.4 mV. With respect to 100 parts by mass of the toner particles, titanium oxide particles (zeta potential at pH = 4, 2.1 mV, specific surface area: 100 m ^{2 /} g) as inorganic fine powders, 2.1 parts by mass, amino-modified silicone oil ( (Amino equivalent = 830, viscosity at 25 ° C. = 70 mm ² / s) 0.8 parts by mass of hydrophobic silica fine powder a having a methanol concentration of 75% at a transmittance of 80% treated with 17 parts by mass, titanic acid 3.0 parts by mass of strontium (primary particle size: 1.5 μm) was added, and externally added and mixed using a Henschel mixer under arbitrary conditions, and sieved with a mesh having an aperture of 150 μm to obtain toner 12. The toner formulation and physical property values are shown in Table 1, Table 2, and Table 3.

<Production Example of Photoreceptor 1>
In the present invention, a cylindrical Al substrate having an outer diameter of 108 mm and a length of 358 mm is used, and the substrate temperature, gas type, gas flow, reaction vessel internal temperature, etc. are appropriately adjusted by high-frequency plasma CVD (PCVD) method. A system photoreceptor can be obtained.

  The following method is used for controlling the charging polarity of the photoreceptor. For example, a charge injection blocking layer composed of an a-Si: H film doped with phosphorus (P) in hydrogenated a-Si (a-Si: H), and light composed of an undoped a-Si: H film A negatively chargeable a-Si photoconductor can be obtained by providing an electrically conductive layer and an interface layer composed of an a-Si: H film doped with boron (B) on a conductive substrate. On the other hand, for example, a charge injection blocking layer composed of an a-Si: H film doped with boron (B), a photoconductive layer composed of an a-Si: H film doped with boron (B), silicon and carbon A positively chargeable a-Si photoconductor can be obtained by providing a surface protective layer composed of a silicon film (a-SiC: H) made of a conductive substrate on a conductive substrate.

  Based on the above manufacturing method, a positively chargeable photoreceptor 1 including a photoconductive layer containing amorphous silicon and a surface protective layer containing amorphous silicon carbide (a-SiC: H) on a cylindrical Al substrate was manufactured.

<Production Example of Photoreceptor 2>
On the basis of the above manufacturing method, a positive charge is provided with a photoconductive layer containing amorphous silicon on a cylindrical Al substrate and a surface protective layer containing amorphous carbon (aC: H) containing carbon atoms as a base and containing hydrogen atoms. Photoconductor 2 was produced.

<Example of production of photoconductor 3>
Based on the above manufacturing method, a positively chargeable photoreceptor 3 including a photoconductive layer containing amorphous silicon and a surface protective layer containing amorphous silicon nitride on a cylindrical Al base was manufactured.

[Example 1]
The peripheral part of the transfer device of a commercially available digital copying machine iR105 (105 cpm, equipped with a-Si photosensitive drum, magnetic one-component reversal jumping development method, manufactured by Canon Inc.) is modified to the transfer belt type shown in FIG. The a-Si photosensitive member was replaced with the photosensitive member 1 of the present invention, and the machine body was modified so that the process speed of the machine body (= the peripheral speed of the photosensitive drum) was 660 mm / sec. The print speed was 110 cpm.

  In this embodiment, the developing process uses a developing device mounted on the iR 105, and adopts a method in which the electrostatic latent image on the photoconductor 11 is reversely developed by a magnetic one-component jumping developing method. As development conditions, a rotatable developing roller including a magnet roller is coated with the magnetic toner of the present invention on a thin layer, a DC bias of +300 V, a Vpp = 1.2 kV, a frequency of 2.7 kHz, a duty wave of 50% rectangular wave. An AC bias was applied. As the setting conditions of the developing device, the distance between the magnetic doctor blade and the developing roller was 210 to 220 μm, the distance from the developing roller to the a-Si photosensitive drum surface was set to 190 to 210 μm, and the non-contact developing condition was set. . The surface potential of the photosensitive drum was developed by setting VD to +380 to +420 V and VL to +30 to +50 V.

  Chloroplane rubber was used as the surface layer material of the transfer belt, and the intrusion amount i of the transfer belt with respect to the photoreceptor was set to 3%. Further, a bias of 6 kV in absolute value was applied to the bias roller 15 on the side opposite to the charging polarity of the toner.

  The schematic diagram of the transfer process shown in FIG. 1 has a structure in which the transfer belt 12 is always pressed against the photoconductor 11 for the sake of simplicity of explanation. However, only when the transfer is performed, that is, the transfer material is the photoconductor. It is also preferable to have a so-called separation / contact function that forms a nip by pressing the transfer belt toward the photosensitive member only when contacting with the toner. In this embodiment, the transfer belt 12 is pressed against the photoconductor 11 side except during the start-up operation and the stop operation of the image forming apparatus (that is, while the process speed (= photoconductor surface speed) of the apparatus main body is unstable). I let you. In this embodiment, the peripheral speed of the transfer belt is set to be the same as the peripheral speed of the photoconductor.

  Using Toner 1, 23 ° C./50% RH environment (shown as NN in Table 4), 23 ° C./5% RH environment (shown as NL in Table 4), and 32 ° C./90% RH environment (shown as HH in Table 4) In this order, a durability test is performed in which a character image with an image ratio of 4% is printed continuously at 300,000 sheets each with A4 horizontal feed. Each of the items of belt cleaning property, other transfer quality (transfer defect and deviation), and image density was evaluated. The evaluation was performed according to the following indicators.

<Evaluation of transfer omission>
At the end of the endurance test in each environment, the vertical and horizontal lines are both printed on 250 g / m ² (A4) paper on both sides of an 8 mm grid pattern with 200 μm, 500 μm, 1 mm, and 2 mm line width repeated. Arbitrary ten places of the print were observed visually and with a magnifying glass (× 30) and classified into the following evaluation ranks.
A: No transfer omission B: Transfer omission is confirmed in part of the field of view by observation using a 30 × magnifier D; Transfer omission is confirmed in part by visual observation D: Overall omission You can check the transfer gap

<Evaluation of transfer belt cleaning properties (transfer belt contamination)>
During the durability test in each environment, the transfer belt surface was visually observed and the back surface of the transfer paper was observed, and the transfer belt cleaning properties (ie, cleanliness) were classified into the following evaluation ranks.
A: There is no stain on the back surface of the transfer paper, and the cleanliness of the transfer belt surface by visual inspection is high. B: There is no stain on the back surface of the transfer paper, but contamination is observed on the surface of the transfer belt C;

<Evaluation of other transfer quality>
In the durability test in each environment, a comprehensive evaluation on the transfer image quality was performed. Specifically, items of transfer failure and transfer misalignment other than transfer skipping were classified into the following evaluation ranks.
A: No transfer failure or transfer deviation B; Minor transfer failure or transfer deviation observed C: Unacceptable transfer failure or transfer deviation observed

<Evaluation of image density>
With respect to the image at the end of the endurance test in each environment, the reflection density was measured using an SPI filter using a Macbeth reflection densitometer (manufactured by Macbeth), and classified into the following evaluation ranks.
A: 1.4 or more B; 1.2 or more and less than 1.4 C; less than 1.2

  The evaluation results are summarized in Table 4.

[Examples 2 to 8]
The evaluation conditions of the evaluation machine (transfer belt penetration amount, transfer belt material, photoconductor No.) were the conditions shown in Table 4, and toners 2 to 8 were evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 4.

[Comparative Examples 1-4]
The evaluation conditions of the evaluation machine (transfer belt intrusion amount, transfer belt material, photoconductor No.) were the conditions shown in Table 4, and toners 9 to 12 were evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 4. As for the evaluation results of <other transfer quality> in Comparative Example 2 and Comparative Example 3, fine image omission due to silica particles or melamine resin particles was confirmed on the printed image. Further, in Comparative Example 2, a slight transfer deviation was confirmed.

It is the schematic of a transfer process. 2 is a partial cross-sectional view of an example of a photoreceptor including a conductive substrate and a photoconductive layer containing amorphous silicon and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride on the substrate. It is a figure which shows the particle size distribution of 256ch obtained in Coulter multisizer IIE (Coulter company make).

Explanation of symbols

11 Photoconductor 12 Transfer belt 13 Drive roller 14 Drive roller 15 Bias roller 16 High-voltage power supply 17 Cleaning backup roller 18 Fur brush 19 Transfer material 21 Conductive substrate 22 Photoconductive layer 23 Surface protective layer 24 Charge injection blocking layer 25 Lower photoconductive layer 26 Upper photoconductive layer 27 Antireflection layer or interface layer

Claims (12)

Using a conductive substrate and a photosensitive member provided with at least a photoconductive layer on the conductive substrate, the surface of the photosensitive member is charged, and an electrostatic latent image is formed on the photosensitive member by exposure. The image is developed with toner to form a toner image, and the toner image is transferred in contact with a transfer material conveyed on an endless transfer conveying means to which a charge having a polarity opposite to that of the toner is applied. In the image forming method,
The endless transfer / conveying means is a transfer belt, and the transfer belt is supported by at least two or more rollers installed on the upstream side and the downstream side in the conveyance direction of a portion in contact with the photosensitive member. The intrusion amount i of the transfer belt with respect to the surface of the photosensitive member is in a range of 0% <i ≦ 5% of the photosensitive member diameter d at the contact portion with the body,
The toner is a one-component toner having at least a toner particle containing a binder resin and a colorant and an inorganic fine powder, and the toner has a uniaxial collapse stress of 0.1 to 3 at a maximum compaction stress of 5 kPa. An image forming method, wherein the toner has a uniaxial collapse stress of 2.5 to 6.0 kPa when the toner has a maximum consolidation stress of 20 kPa.   2. The image forming method according to claim 1, wherein the inorganic fine powder is at least one oxide selected from magnesium oxide, alumina, zinc oxide, and titanium oxide.   3. The image forming method according to claim 1, wherein the content of the inorganic fine powder is 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles.   The photoreceptor includes a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. The image forming method according to any one of claims 1 to 3.   The image forming method according to claim 1, wherein the toner particles constituting the toner contain a magnetic material.   The image forming method according to claim 1, wherein the toner is positively charged. Using a conductive substrate and a photosensitive member provided with at least a photoconductive layer on the conductive substrate, the surface of the photosensitive member is charged, and an electrostatic latent image is formed on the photosensitive member by exposure. The image is developed with toner to form a toner image, and the toner image is transferred in contact with a transfer material conveyed on an endless transfer conveying means to which a charge having a polarity opposite to that of the toner is applied. In the image forming apparatus,
The endless transfer / conveying means is a transfer belt, and the transfer belt is supported by at least two or more rollers installed on the upstream side and the downstream side in the conveyance direction of a portion in contact with the photosensitive member. The intrusion amount i of the transfer belt with respect to the surface of the photosensitive member is in a range of 0% <i ≦ 5% of the photosensitive member diameter d at the contact portion with the body,
The toner is a one-component toner having at least a toner particle containing a binder resin and a colorant and an inorganic fine powder, and the toner has a uniaxial collapse stress of 0.1 to 3 at a maximum compaction stress of 5 kPa. An image forming apparatus having a uniaxial collapse stress of 2.5 to 6.0 kPa when the toner has a maximum consolidation stress of 20 kPa.   The image forming apparatus according to claim 7, wherein the inorganic fine powder is at least one oxide selected from magnesium oxide, alumina, zinc oxide, and titanium oxide.   The image forming apparatus according to claim 7 or 8, wherein the content of the inorganic fine powder is 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the toner particles.   The photoreceptor includes a conductive substrate, a photoconductive layer containing at least amorphous silicon on the conductive substrate, and a surface protective layer containing amorphous silicon and / or amorphous carbon and / or amorphous silicon nitride. The image forming apparatus according to any one of claims 7 to 9.   The image forming apparatus according to any one of claims 7 to 10, wherein the toner particles constituting the toner contain a magnetic substance.   The image forming apparatus according to claim 7, wherein the toner is positively charged.

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