JP4366295B2 - Developing method, image forming method, developing apparatus, electrophotographic cartridge, and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic contact development system in which the roughness and solid white image defect occurring under low humidity are suppressed and further, a recovery failure ghost is suppressed while image density is appropriately maintained even when a cleaner system is applied. <P>SOLUTION: The magnetic toner is used in a magnetic one-component development system which uses a developer carrier internally having a fixed magnetic field generating means, and having an elastic body layer on the surface, attracts the toner having magnetism toward the surface of the developer carrier by a developer amount regulating means, regulates the developer amount M on the surface of the developer carrier to 5.0 to 6.0 g/m<SP>2</SP>, and makes development while pressing the developer carrier to a body to be developed and rotating the same. The average circularity of the magnetic toner is &ge;0.945, the residual magnetization of the magnetic toner is assumed as &sigma;r(Am<SP>2</SP>/kg), 1.0&le;&sigma;r&le;6.0 and 1.4&le;M/&sigma;r&le;15. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a developer for developing a photoconductor as a developing target. More specifically, the present invention relates to a magnetic toner for contact development that develops in contact with a photoreceptor. The present invention also relates to a developing method for developing a photoreceptor and an image forming method. More specifically, the present invention relates to a contact development method in which development is performed in contact with a photoreceptor. Furthermore, the present invention relates to a developing device such as a copying machine or a printer that uses the above developing method as a developing process for a photosensitive member. More specifically, the present invention relates to a developing device, an electrophotographic cartridge, and an image forming apparatus using the above developing method.

  As conventional one-component development methods, (1) non-magnetic contact development method and (2) magnetic non-contact development method are widely used.

(1) Non-magnetic contact development method A method has been proposed in which development is performed by supporting a non-magnetic developer on a developing roller, which is a developer carrying member, and bringing it into contact with the surface of a photoreceptor, which is a development target. The developer in the developing device is supplied to the developing roller by a mechanical stirring mechanism, gravity, or electrostatic force. For example, an elastic roller that contacts the developing roller is provided to carry the developer. In addition to the purpose of making the developer on the developing roller uniform, the elastic roller also has a function of temporarily removing the developer remaining on the developing roller without shifting to the developing object. A DC bias is applied between the photoconductor substrate and the developing roller.

(2) Magnetic non-contact development method In this method, a magnetic one-component developer is used, the developer is carried on a developing sleeve containing a magnet, and a predetermined minute gap is formed on the surface of the developer carrying member on the photosensitive member. It develops with the developer which makes it oppose and flies through this clearance gap. The developer in the developing device is conveyed to the developing sleeve by a mechanical stirring mechanism or gravity, and the developer is supplied to the developing sleeve under a certain magnetic force by a magnet. Then, a constant developer layer is formed on the developing sleeve by the regulating means and used for development. The force acting on the developer by the magnet is positively used not only in the transport of the developer but also in the developing section. In the developing portion, the developer is prevented from moving to the non-image portion and causing image defects such as fogging. That is, at the time of development, the developer receives a magnetic force toward the magnet contained in the developing sleeve. A bias in which an AC bias is superimposed on a DC bias is used for flying the developer. The DC bias voltage is adjusted to a value between the image portion potential and the non-image portion potential of the photoreceptor. Furthermore, the AC voltage is superimposed, and in some cases, a voltage exceeding the image portion potential is applied. In other cases, a voltage lower than the non-image portion potential is applied, so that the developer reciprocates between the image portion and the non-image portion. As a result, the image portion is developed with a developer.

(3) Others: Magnetic contact development method There has also been proposed a magnetic contact development method that has some of the characteristics of both (1) non-magnetic contact development method and (2) magnetic non-contact development method (for example, (See Patent Documents 1 and 2). According to these documents, by controlling the saturation magnetization amount or toner shape of the magnetic toner to be used, it is possible to achieve both the reduction in fog and the high image quality, which are the features of both types.

Cleanerless (Toner Recycling) System From the viewpoint of simplifying the device configuration and eliminating waste, an electrophotographic process in which the drum cleaner is discarded and the toner is recycled in the device, a so-called cleanerless system has been proposed. For example, an image forming apparatus has been proposed that uses the above-described nonmagnetic contact development to collect the developer that remains at the same time as development (see, for example, Patent Document 3). In addition, an image forming apparatus is also disclosed that collects the developer remaining after transfer at the same time during development using the above-described magnetic non-contact development method (see, for example, Patent Document 4). In any of the techniques, recovery of the developer remaining after transfer can be said to be the greatest technical point.

Japanese Patent Laid-Open No. 7-301948 Japanese Patent No. 3274096 Patent No. 2598131 JP-A-10-307455

  In conventional non-magnetic contact development, a reduction in fogging performance during durability often becomes a problem. In other words, in addition to being weak against fogging due to its inherently weak binding force on the developing roller, the toner characteristics deteriorate as the developer on the developing roller is mechanically stripped off by the elastic roller, resulting in toner friction. This is a phenomenon in which fog is deteriorated due to a decrease in charging characteristics. The fog is an image defect in which toner is developed in a white portion (unexposed portion) that is not originally printed, and appears as a background stain. Although it is possible to weaken the rubbing force of the elastic roller in order to prevent the toner characteristics from deteriorating, it is difficult to achieve compatibility with ghost image defects. The ghost image means a ghost that appears with a phase difference between the outer circumference of the developing roller or the photosensitive member, and the ghost image here is a uniform intermediate in which an image (characters, etc.) previously developed on the developing roller is developed next time. It is a phenomenon that appears in toned images. Also, the presence of ghost means that there is toner that remains on the developing roller without being peeled off. Since the remaining toner is continuously rubbed by the elastic roller, it is not preferable from the viewpoint of deterioration of toner characteristics. As described above, the adjustment of the rubbing force of the elastic roller is not only contradicted from the viewpoint of fog and ghost, but also has a problem that contradicts the problem of fog alone due to deterioration. Hardening the toner can be mentioned as one of the solutions, but it is not preferable because the fixing property of the toner is extremely deteriorated. For example, when this method is combined with a cleanerless system, the deterioration of fog is directly linked to contamination of the charging member, and the non-image portion potential is lowered in the reversal development method, so that the fog as an image defect is further accelerated. .

  Further, when the toner characteristics are deteriorated, there is a problem that the toner characteristics are easily influenced by circulation in the developing device. This will be specifically described below. In circulation using mechanical or gravity, there is an area where the agent hardly circulates because the agent is hardly changed especially around the developing roller. The physical properties of the toner existing in this region are considered to be close to those of the unused toner. On the other hand, the circulating agent has a certain characteristic deterioration. There are two types of agents in the developing unit. When the toner in the container decreases with use, both of them are mixed, but at this time, aggregation and the like are likely to occur and problems such as fogging occur. Further, there is an image defect caused by the elastic roller itself. The elastic roller is in the form of a sponge from the viewpoint of toner stripping supply performance, but when the developer is compressed into the sponge cells to form agglomerates, they come off the sponge and come out on the surface. In particular, image defects occur in the halftone. Further, in the cleanerless system, paper dust enters the elastic roller, resulting in an image defect of the elastic roller cycle.

  Further, in the contact developing device, an image defect may occur in the solid white. This defect occurs in the sleeve cycle and becomes a large image defect of several millimeters width. The cause is expected to result from the strong adhesion of the developer sandwiched between the developing roller and the photosensitive drum to the developing roller.

  In addition, there is a problem of toner scattering. When the force for supporting the developer on the developing roller is reduced, not only the fog but also the toner is scattered in the apparatus, causing various troubles.

  On the other hand, in magnetic non-contact development, there is an image defect due to magnetic spikes. The problem is that the uniformity of the thin line differs vertically and horizontally. When developing while the magnetic spike moves in parallel with the photosensitive drum traveling direction, the uniformity of the fine line is good, and the direction perpendicular to it tends to be interrupted. In some cases, image edge defects may be observed. The edge of the high density portion, particularly the downstream side of the process is developed deeply, and the edge of the halftone portion adjacent to the high density portion is developed lightly. The cause is expected to be developed in a non-contact manner while the developer is reciprocated by an AC electric field. In the developing portion, the toner moves in the surface direction, and particularly the toner stays in the downstream of the edge portion. Further, when combined with a cleanerless system, there is a problem that the transfer residual toner on the photosensitive drum is low because of non-contact, and the transfer residual toner becomes ghost and appears in solid white or halftone. . In addition, white spots may occur in solid black. This white spot is likely to occur when paper dust is mixed between the developing roller and the photosensitive drum under high humidity. It is expected that a bias leak occurs between the developing roller and the photosensitive drum, and as a result, the latent image potential on the photosensitive drum is increased (to the negative side).

  On the other hand, in magnetic contact development, since the developer can be supplied to the developing roller by receiving a certain magnetic force by a magnet, an elastic roller is unnecessary, and deterioration of fog can be avoided, and it also has an advantageous effect on toner scattering. In addition, it is expected that high image quality without white spots or image edge defects may be achieved by contact development. However, the magnetic force that pulls the developer back from the photosensitive member to the developing roller works, so that the image density is difficult to achieve, and a collection of magnetic spikes with non-uniform length is pressed at the contact portion between the photosensitive member and the developing roller. In addition, since the longer magnetic spikes are rubbed harder, variations in the triboelectric charge amount occur between the magnetic spikes, and in particular, the roughness appears on the halftone image. In addition, the longer the magnetic head, the higher the triboelectric charge amount, so that strong electrostatic adhesion to the developing roller is likely to occur. In this developing method, since there is no mechanical peeling by the elastic roller, once the developer adheres, it continues to grow on the developing roller, which spurs the occurrence of the image defect in the solid white. Such a rough image on a halftone image or an image defect in solid white is a phenomenon of great concern under low humidity where the triboelectric charge amount tends to increase. Further, combining the magnetic contact development system with the cleanerless system is advantageous in terms of durability because of less deterioration of fog. On the other hand, in order to improve the recoverability of the transfer residual toner, it is necessary to set a strong magnetic force between the developer and the developing roller. As a result, this leads to a decrease in image density and the density of the toner is low. Since sparse magnetic heads with a more uneven height will be formed, the image defects in the roughness and solid white will be worsened. On the other hand, if the magnetic force is set too weak, the transfer residual toner recoverability is reduced and a ghost is generated, and the developer supply capability to the developing roller is also reduced, so that the image density is also lowered. In other words, the use of magnetic contact development in a cleanerless system has the advantage of improving the fog, while suppressing the roughness and solid white image defects while improving the image density appropriately and improving the recovery failure ghost. However, there are still technical problems to be solved even though they are not compatible.

  An object of the first invention related to the present application is to provide a new and excellent magnetic toner capable of solving the above-described problems.

  The object of the second invention related to the present application is to solve the above-mentioned problems and to provide a new and excellent development method and image forming method.

  The object of the third invention related to the present application is to provide a new and excellent developing device, electrophotographic cartridge and electrophotographic image forming apparatus capable of solving the above-mentioned problems.

First invention according to the present application, using a developer carrying member having an elastic layer on the surface and has a magnetic field generating means fixed inside, the developer bearing a toner having magnetic by the magnetic field generating means of the fixed drawn to the body surface, the developer amount M on the developer carrying member surface was regulated to 5.0 g / m ² or more 16.0 g / m ² or less by a developer amount regulating means, the strip conductor means and image exposure means A magnetic contact developing method including at least a step of developing the electrostatic latent image formed on the developing member while pressing and rotating the developer carrying member against the developing member;
The average circularity of the magnetic toner is 0.945 or more,
When the residual magnetization of the magnetic toner is σr (Am ² / kg), 1.0 ≦ σr ≦ 6.0
And
1.4 ≦ M / σr ≦ 15
The present invention relates to a magnetic contact development method.

According to a second aspect of the present application, in the above development step, the moving speed of the developer carrier surface in the pressing area is 1.01 to 2.00 times the moving speed of the surface of the developing object. The present invention relates to a developing method.

According to a third aspect of the present application, when the weight average particle diameter of the magnetic toner is D4 (μm),
0.14 ≦ M / (σr × D4) ≦ 4.0
The present invention relates to a developing method.

A fourth invention according to the present application relates to the developing method, wherein the magnetic toner has an average circularity of 0.950 or more.

According to a fifth aspect of the present application, the above magnetic toner carries at least the surface carrying an inorganic fine powder A having an average particle size of 5 nm to 25 nm and an inorganic fine powder B having an average particle size of 30 nm to 3 μm. The present invention relates to a developing method.

A sixth invention according to the present application relates to the developing method, wherein the inorganic fine powder A is at least one selected from silica, titanium oxide, and alumina.

A seventh invention according to the present application relates to a developing method, wherein the inorganic fine powder A is subjected to a hydrophobic treatment.

According to an eighth aspect of the present application, a developing bias is applied between the developer carrying member and the member to be developed, and the magnetic toner is transferred onto the member to be developed. The present invention relates to a developing method characterized in that, in a developing step of developing the formed electrostatic latent image, the developing bias is a DC voltage superimposed on an alternating voltage.

According to a ninth aspect of the present application, there is provided a charging step in which at least a charging member is brought into contact with a developing member and charging is performed by applying a voltage from the outside, and an electrostatic latent image is formed on the developing member by irradiation with light energy. An image forming step, a developing step of developing the developer holding the electrostatic latent image on the surface with a developer and visualizing the developer, and a transfer of transferring the developer developed on the developing member to a transfer material And an image forming method, wherein the developing step is performed by any one of the developing methods described above.

A tenth invention according to the present application relates to the above-described image forming method, wherein the developing step also serves as a cleaning step for collecting the developer remaining on the member to be developed after the transferring step.

An eleventh invention related to the present application relates to a developing device for developing by any one of the developing methods.

According to a twelfth aspect of the present application, there is provided: a developing object, a charging device that charges the developing object, an exposure unit that forms an electrostatic latent image on the developing object, and a developing device that develops the electrostatic latent image. The present invention relates to an electrophotographic cartridge formed integrally, wherein the developing device is the developing device described above.

According to a thirteenth aspect of the present application, there is provided: a developing object, a charging device that charges the developing object, an exposure unit that forms an electrostatic latent image on the developing object, and a developing device that develops the electrostatic latent image. An electrophotographic cartridge comprising: the electrophotographic cartridge, wherein the developing device is the developing device, and the transfer residual developer remaining on the development target is collected by the developing device. .

According to a fourteenth aspect of the present application, there is provided a transfer device that detachably equips any one of the electrophotographic cartridges described above, and that transfers a developer image formed on the member to be developed to a transfer material, and the transfer material The present invention relates to an electrophotographic image forming apparatus comprising a fixing device for fixing the developer image on a transfer material.

  According to the present invention, it is possible to suppress the roughness and solid white image defects that are seen when the magnetic contact development method is used under low humidity, and a high-quality image can be obtained. Further, if this developing method is employed in a cleanerless system in which recovery of transfer residual toner is an important technology, it is possible to suppress recovery failure ghosts while maintaining an appropriate image density.

  FIG. 1 is a schematic configuration diagram of an image recording apparatus using a developing device according to the present invention. The image recording apparatus of this embodiment is a laser printer of a toner recycling process (cleanerless system) using a transfer type electrophotographic process. In this embodiment, the drum cleaner is discarded and the transfer residual toner is recycled. At that time, the toner is circulated and collected in the developing unit so that the transfer residual toner does not adversely affect other processes such as charging.

(1) Overall Schematic Configuration of Image Recording Apparatus 1 is a photosensitive drum which is a development target, and this photosensitive drum 1 is rotationally driven at a constant speed in a clockwise direction indicated by an arrow.

  Reference numeral 2 denotes a charging member as charging means for the photosensitive drum 1, and reference numeral 21 denotes a charging roller. The charging roller 21 is a conductive elastic roller, and is in pressure contact with the photosensitive drum 1 with a predetermined pressing force to form a charging portion n between the charging roller 21 and the photosensitive drum 1. In this example, the charging roller is driven. The rotation speed of the charging roller is adjusted so that the surface speed of the charging roller and the surface speed of the photosensitive drum (process speed) are the same. Further, the charging roller is provided with a charging roller contact member 22 for the purpose of preventing toner contamination of the charging roller. By driving the charging roller, the charging roller surely comes into contact with the photosensitive member and the contact member 22 and charges the toner negatively (regular polarity). Even when the charging roller is contaminated with toner of the opposite polarity (plus polarity) to its charging polarity, the toner charge can be charged from plus to minus and quickly discharged from the charging roller and collected by the developer. It becomes possible.

  S 1 is a charging power source that applies a charging bias to the charging roller 21. In this example, a DC voltage equal to or higher than the discharge start voltage is applied to the contact portion between the charging power source S1 and the charging roller 21.

  A laser beam scanner (exposure apparatus) 3 includes a laser diode, a polygon mirror, and the like. The laser beam scanner 3 outputs laser light whose intensity is modulated in accordance with a time-series electric digital pixel signal of target image information, and scans and exposes the uniformly charged surface of the rotating photosensitive drum 1 with the laser light. To do. By this scanning exposure L, an electrostatic latent image corresponding to target image information is formed on the surface of the rotary photosensitive drum 1.

  Reference numeral 5 denotes a medium resistance transfer roller as a contact transfer means, which is brought into pressure contact with the photosensitive drum 1 to form a transfer nip portion b. A transfer material P as a recording medium is fed to the transfer nip b from a paper feed unit (not shown) at a predetermined timing, and a predetermined transfer bias voltage is applied to the transfer roller 5 from a transfer bias application power source S3. As a result, the toner image on the photosensitive drum 1 side is sequentially transferred onto the surface of the transfer material P fed to the transfer nip portion b.

  The transfer roller 5 used in this example has a medium resistance foamed layer 5a formed on a cored bar 5b, for example. The transfer material P introduced into the transfer nip portion b is nipped and conveyed by the transfer nip portion b, and the toner images formed and supported on the surface of the rotary photosensitive drum 1 on the surface side thereof are successively subjected to electrostatic force and pressing force. Will be transcribed.

  Reference numeral 6 denotes a fixing device such as a heat fixing method. The transfer material P that has been fed to the transfer nip b and has received the transfer of the toner image on the photosensitive drum 1 side is separated from the surface of the rotating photosensitive drum 1 and introduced into the fixing device 6 to receive the fixing of the toner image. It is discharged out of the apparatus as an image formed product (print copy).

  The photosensitive drum 1 is charged again by the charging device 20 and repeatedly used for image formation.

  Reference numeral 400 denotes a developing device (developer). The toners 410 and t are charged with a constant frictional charge, and an electrostatic latent image on the photosensitive drum 1 is developed in the developing area a by the developing bias applied between the toner carrier and the photosensitive drum 1 by the developing bias applying power source S2. Image.

  A developing sleeve 440 includes a magnet roll 442c and serves as a developer carrying member. The developing sleeve 440 is configured by forming a nonmagnetic conductive elastic layer 442a on an aluminum cylinder 442b, and is in contact with the photosensitive drum 1 with a certain amount of pressure. The pressure between the photosensitive drum and the developing sleeve was controlled by the drawing pressure. The drawing pressure refers to the force when pulling the SUS plate between the developing sleeve and the photosensitive drum with the same 30 μm SUS plate sandwiched between two plates of 30 μm thickness. It is a linear pressure equivalent value converted to a per unit. The developing sleeve 440 was manufactured by kneading and extruding materials.

  Here, when the micro hardness of the developing sleeve 440 is less than 40, the surface of the elastic layer is significantly scraped or scratched by sliding contact with the regulating member, the image carrier, etc., and image defects such as roughness are likely to occur. Furthermore, set marks are also likely to be generated by long-term pressing, and 40 or more is preferable. On the other hand, if it exceeds 95, the image carrier is scraped or scratched due to sliding contact with the photosensitive drum, and a solid white image defect is likely to occur. Further, it is difficult to uniformly contact the developing sleeve in the axial direction of the developing sleeve, and a density difference between right and left on the image is likely to occur.

  Further, the thickness of the elastic layer 442a is preferably 50 μm or more and 2000 μm or less, and is considerably thinner than the conventional one. However, if the thickness is less than 50 μm, the surface of the image carrier may be scraped or scratched when it comes into contact with the image carrier, and image defects may occur. In some cases, the triboelectric charge of long magnetic spikes increases. May cause rustling. On the other hand, if it exceeds 2000 μm, the magnetic force exerted on the surface of the image bearing member from the fixed magnetic field generator included is weakened and tends to be unfavorable for fogging or sufficient developer supply capability to form a good image. May not be satisfied. In addition, poorly recovered ghosts may be seen in cleanerless systems.

  In the present invention, the surface hardness measured with a micro hardness meter was measured using a micro hardness meter (Asker MD-1 F360A: manufactured by Kobunshi Co., Ltd.). The surface roughness measuring instrument is manufactured by Kosaka Laboratory Co., Ltd., and the contact detection unit PU-DJ2S is used for Surfcoder SE3400. The measurement conditions are 2.5 mm measuring length, 2000 times vertical magnification, 100 times horizontal magnification, Cut-off 0.8mm, filter setting 2CR, and leveling setting were performed with front data.

  The magnet 442c is a fixed magnet as magnetic field generating means for generating a magnetic force at each location on the sleeve. A magnetic flux density of 500 G is generated at an absolute value of the peak density at each position of the developing unit, the layer regulating unit, the supplying unit, and the collecting unit. The measurement of the magnetic flux density in the present invention was performed using a Gauss meter series 9900, probe A-99-153 manufactured by Bell. The Gauss meter has a rod-shaped axial probe connected to the Gauss meter body. The developing sleeve is fixed horizontally, and the magnet inside is mounted rotatably. Place the probe in a horizontal position at a right angle with a slight gap to the developing sleeve, and fix it so that the center of the developing sleeve and the center of the probe are located on substantially the same horizontal plane, and measure the magnetic flux density in that state. To do. The magnet is a cylindrical body substantially concentric with the developing sleeve, and the interval between the developing sleeve and the magnet may be considered to be equal everywhere. Therefore, by measuring the surface position of the developing sleeve and the magnetic flux density in the normal direction at the surface position while rotating the magnet roller 442c, it is possible to replace those measured at all positions in the circumferential direction of the developing sleeve 440. The peak intensity at each position was determined from the obtained magnetic flux density data in the week direction.

  The toner t is subjected to layer thickness regulation and charge application by the regulation blade 420 in the process of being conveyed on the developing sleeve 440 while receiving the magnetic force from the magnet roll 442c. Reference numeral 430 denotes an agitating member that circulates the toner 410 in the developing container 450 and sequentially conveys the toner within the reach of the magnetic force around the sleeve.

In this developing apparatus, the surface roughness of the developing sleeve, the drawing pressure between the developing roll and the regulating blade 420, and the blade length are set appropriately, and the toner coat amount M on the developing sleeve, which is one of the features of the present invention, is strictly controlled. Is doing the right control. The blade free length means the length of the free end when the contact portion between the blade and the sleeve is used as a fulcrum. Toner coating amount M of the present invention should be controlled below 5.0 g / m ² or more 16.0 g / m ^2. If it is less than 5.0, sufficient image density cannot be obtained. On the other hand, if it exceeds 16.0, the magnetic spikes of the toner become long, the roughness is noticeable, and the toner is strongly pressed between the photosensitive member and the developing sleeve, resulting in a solid white image defect. This effect is more prominent when controlled to 15.0 g / m ² or less.

  The toner t coated on the developing sleeve 440 is conveyed to a developing portion (developing region portion) a which is a facing portion between the photosensitive drum 1 and the sleeve 440 by the rotation of the sleeve 442b. A developing bias voltage obtained by superimposing an AC voltage on a DC voltage is applied to the sleeve 440 from a developing bias applying power source S2.

  In this embodiment, it is preferable that the peripheral speed ratio of the developing sleeve peripheral speed to the photosensitive drum peripheral speed is 1.01 or more and 2.00 or less. If it is less than 1.01, the absolute amount of toner transferred from the developing sleeve to the photosensitive drum is small, and it may be difficult to obtain a sufficient image density. On the other hand, if it exceeds 2.00, durability and image density decrease due to developer deterioration and fog deterioration become remarkable. In this embodiment described later, the electrostatic latent image on the photosensitive drum 1 side is reversely developed with the toner t under these conditions.

  Here, as another feature of the present invention, the average circularity of the toner t is controlled to 0.945 or more.

The spherical toner has a more uniform surface charge retention state during frictional charging than the irregular toner, and in the magnetic development system, the lengths of individual magnetic spikes are uniform. Accordingly, the individual magnetic spikes are pressed evenly at the contact portion between the photosensitive drum and the developing sleeve, so that there is no variation in the frictional charge amount, and a high-definition image with high image density and no roughness can be stably obtained. When the average circularity is less than 0.945, the frictional charge amount varies with long-term use under low humidity where the frictional charge amount tends to be high. Therefore, it is difficult to maintain a high image density only by controlling the toner coat amount M to 5.0 g / m ² or more, and halftone only by controlling the toner coat amount M to 16.0 g / m ² or less. It is also very difficult to keep the roughness on the image good. Preferably, if the average circularity is 0.950 or more, a higher quality image can be obtained, and if it is 0.955 or more, it is even more preferable.

  In addition, “FPIA-1000”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity. A calculation method is used in which 1.00 is divided into 61 classes and the average circularity is calculated using the center value and frequency of the dividing points. However, there is very little error between the average circularity value calculated by this calculation method and the average circularity value calculated by the above-described calculation formula that directly uses the circularity of each particle. In the present invention, the concept of the calculation formula that directly uses the circularity of each particle described above is used in the present invention for reasons of data handling such as a short calculation time and simplification of the calculation calculation formula. It is also possible to use such a calculation method that is used and partially changed.

  As a specific measurement method, about 5 mg of developer is dispersed in 10 ml of water in which about 0.1 mg of a surfactant is dissolved, a dispersion is prepared, and ultrasonic waves (20 KHz, 50 W) are applied to the dispersion for 5 minutes. Irradiation is performed, the dispersion concentration is set to 5000 to 20,000 / μl, and measurement is performed by the above-described apparatus to determine the average circularity of a particle group having a circle-equivalent diameter of 3 μm or more.

  The average circularity in the present invention is an index of the degree of unevenness of the developer, and is 1.000 when the developer is a perfect sphere, and the average circularity becomes smaller as the developer surface shape becomes more complex. Become.

  In this measurement, the reason why the circularity is measured only for the particle group having an equivalent circle diameter of 3 μm or more is that the particle group of the external additive existing independently of the toner particles in the particle group having an equivalent circle diameter of less than 3 μm. This is because the circularity of the toner particle group cannot be accurately estimated due to the influence of such a large amount.

  As a means for setting the average circularity of the magnetic toner to 0.945 or more, a raw material is premixed and then kneaded, pulverized and classified to produce a toner. After pulverization or classification, a spray drying method or a mechanochemical method is used. However, the surface modification process is complicated and its control is not easy. Therefore, it is preferable to employ a pulverizing means using a special pulverizing apparatus because the process can be simplified. Specific examples of the pulverizer include a pulverizer KTM manufactured by Kawasaki Heavy Industries, Ltd., a turbo mill manufactured by Turbo Industry Co., Ltd., and the like, and these devices are preferably used as they are or after being appropriately modified. Then, surface modification is performed according to the degree of average circularity of the pulverized particles.

As a further feature of the present invention, when the residual magnetization of the toner t is σr (Am ² / kg),
1.0 ≦ σr ≦ 6.0
And the relationship with the toner coat amount M,
1.4 ≦ M / σr ≦ 15
It is in the point to control.

  If σr exceeds 6.0, the toner cohesiveness around the developing sleeve deteriorates, and it becomes difficult to strictly control the toner coating amount. Since the magnetic force with the roller also increases, the image density also decreases. On the other hand, if σr is less than 1.0, the characteristics of magnetic development may be weakened and fogging may be deteriorated. In addition, when a cleanerless system is used, the recoverability of transfer residual toner is reduced and a poor recovery ghost is observed. It is done.

  Further, when the toner density M is set high with an emphasis on image density, it is difficult to control the triboelectric charge amount, so it is important to suppress fogging, and it is necessary to increase σr. When importance is attached to the suppression of defects, it is necessary to set M to a small value. In this case, σr must also be set to a small value in order to increase the image density. That is, a proportional relationship is required between M and σr, and according to studies by the present inventors, it has been found that the range of the proportionality constant M / σr needs to be controlled within the above range. If M / σr is less than 1.4, a sufficient image density cannot be obtained, and if M / σr exceeds 15, it is difficult to suppress fogging. It is done.

  In the present invention, the residual magnetization of the magnetic toner was measured with a vibration magnetometer VSM-3S-15 (manufactured by Toei Kogyo Co., Ltd.) in a 1 K Oersted (79.58 kA / m) magnetic field.

  As a means for controlling the residual magnetization σr of the magnetic toner according to the present invention to 1.0 or more and 6.0 or less, any of adjustment of the magnetic substance content in the toner, adjustment of σr of the magnetic substance, and the like are possible.

  When adjusting the σr of the toner by the magnetic substance content, the preferable magnetic substance content is 30 parts by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the binder resin in the toner. If the magnetic substance content is less than 30 parts by weight, it may be difficult to control the triboelectric charge amount under low humidity. If the magnetic substance content exceeds 150 parts by weight, the toner fixing property may be adversely affected. .

When the weight average particle diameter of the magnetic toner according to the present invention is D4 (μm),
0.14 ≦ M / (σr × D4) ≦ 4.0
It is one of the very effective usage forms to control and use.

  For example, as described above, when the toner coat amount M is set to be high, it is important to suppress fogging. As a suppression method, in addition to controlling the toner σr, a means for increasing the toner particle diameter can be mentioned. . That is, if the magnetic substance content is constant, increasing the toner particle diameter increases the magnetic substance content per particle and the magnetic characteristics per particle. In other words, as a means for improving the fog, as in the effect of σr described above, M and D4 must also have an appropriate proportional relationship. Therefore, the present inventors have also examined an appropriate range of M / (σr × D4). As a result, by controlling the range from 0.14 to 4.0, a sufficient image density can be obtained, while fogging, blurring, and solid white are obtained. It was found that image defects can be suppressed well, and that even if a cleanerless system is adopted, it becomes easier to prevent poor recovery ghosts.

  Next, the toner according to the present invention will be described.

  From the viewpoint of storage stability, the resin composition according to the toner of the present invention has a glass transition temperature (Tg) of 45 to 80 ° C., preferably 50 to 70 ° C. When Tg is lower than 45 ° C., This may cause toner deterioration and offset during fixing. On the other hand, when Tg exceeds 80 ° C., fixability tends to decrease.

  As a method for measuring the glass transition temperature of the resin of the present invention, a differential thermal analysis measurement device (DSC measurement device), DSC-7 (manufactured by Perkin Elmer), EXSTAR6000, SSC / 5200 (manufactured by Seiko Instruments Inc.), DSC2920MDSC ( TA Instruments, etc.) can be used under the following conditions.

<Method for measuring glass transition temperature of resin>
Sample: 0.5-2 mg, preferably 1 mg
Temperature curve: Temperature increase I (20 ° C. to 180 ° C., temperature increase rate 10 ° C./min)
Temperature drop I (180 ° C. to 10 ° C., temperature drop rate 10 ° C./min)
Temperature increase II (10 ° C to 180 ° C, temperature increase rate 10 ° C / min)
Measurement method: Place the sample in an aluminum pan, and use an empty aluminum pan as a reference. The point of intersection between the line of the midpoint of the base line before and after the endothermic peak and the differential heat curve was defined as the glass transition point Tg.

  The binder resin component used in the present invention has a Mn (number average molecular weight) of 3000 to 20000 and a Mw (weight average molecular weight) of 50,000 to 500,000 in the molecular weight measured by GPC of the THF soluble component. It is preferable that it is the range of these. Within this range, the balance between fixability and durability is very good.

  These binder resin components can be mixed and dispersed in advance in the production of the magnetic toner. By mixing the wax component in advance, phase separation in the micro region is relaxed, and a good dispersion state is obtained.

  In the present invention, the molecular weight distribution of the toner or binder resin by GPC using THF (tetrahydrofuran) as a solvent is measured under the following conditions.

The column is stabilized in a 40 ° C. heat chamber, and THF as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml per minute, and about 100 μl of a sample THF solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, a product having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used, and at least about 10 standard polystyrene samples are suitably used. . An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, a combination or manufactured by Showa Denko KK of shodex GPC KF-801,802,803,804,805,806,807,800P, Tosoh Corp. of _{TSKgelG1000H (H XL), G2000H (} H XL), G3000H (H XL) , G4000H (H _XL ), G5000H (H _XL ), G6000H (H _XL ), G7000H (H _XL ), and TSK guard column.

  The sample is prepared as follows.

  Put the sample in THF, leave it 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 this time, the sample is left in THF for 24 hours or longer. Thereafter, a sample processing filter (pore size 0.45 to 0.5 μm, for example, Mysori Disc H-25-5 manufactured by Tosoh Corp., Excro Disc 25CR manufactured by Gelman Science Japan Co., Ltd., etc.) can be used. This is a measurement sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

  As the kind of the binder resin in the present invention, styrene resin, styrene copolymer resin, polyester resin, polyol resin, polyvinyl chloride resin, phenol resin, natural modified phenol resin, natural resin modified maleic resin, acrylic resin, Examples include 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.

  As a comonomer for the styrene monomer of the styrene copolymer, a styrene derivative 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 in the present invention preferably has an acid value in the range of 1 to 100 mgKOH / g. Particularly preferred is a resin having an acid value of 1 to 70 mgKOH / g. If it exceeds 70 mgKOH / g, the triboelectric charge amount under high humidity is insufficient, and if it is less than 1 mgKOH / g, the triboelectric charging rate under low humidity becomes slow.

  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 for controlling 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 used in the present invention is preferably produced by using a polyfunctional polymerization initiator as exemplified below alone or in combination with a monofunctional polymerization initiator.

  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 an amount of 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of 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 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。）
また、（Ｆ）式で示されるジオール類；

(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);

が挙げられる。

Is mentioned.

  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.

  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; oxide 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, spermaceti; mineral systems such as ozokerite, ceresin, petrolactam Waxes; waxes mainly composed of aliphatic esters such as montanic acid ester wax and castor wax; those obtained by partially or fully deoxidizing aliphatic esters such as deoxidized carnauba wax . Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinal acid; stearyl alcohol Saturated alcohol such as eicosyl alcohol, behenyl alcohol, cannavir alcohol, seryl alcohol, melyl alcohol, or alkyl alcohol having a long chain alkyl group; polyhydric alcohol such as sorbitol; linoleic acid amide, oleic acid amide, lauric acid Aliphatic amides such as acid amides; saturated aliphatic bisamides such as methylene bisstearic acid amide, ethylene biscapric acid amides, ethylene bislauric acid amides, hexamethylene bisstearic acid amides; Unsaturated fatty acid amides such as inamide, 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; aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (commonly referred to as metal soap); aliphatic hydrocarbons Wax grafted with a vinyl monomer such as styrene or acrylic acid; Partial esterified product of fatty acid and polyhydric alcohol such as behenic acid monoglyceride; Hydroxyl group obtained by hydrogenating vegetable oil Methyl ester compounds It is.

  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 deposition method, a low molecular weight solid fatty acid, a low molecular weight A solid alcohol, a low molecular weight solid compound, and other impurities are preferably used.

  As the colorant of the present invention, magnetic particles may be used alone, or other colorants such as carbon black may be used in combination. As the magnetic particles, iron oxides such as magnetite, maghemite, and ferrite are used, and those containing non-ferrous elements on or inside the iron oxide are also preferable.

  The non-ferrous element content is preferably 0.05 to 10% by mass, and particularly preferably 0.1 to 5% by mass, based on the iron element.

  These different elements are preferably elements selected from magnesium, aluminum, silicon, phosphorus, and sulfur. The following lithium, beryllium, boron, germanium, titanium, zirconium, tin, lead, zinc, calcium, barium, scandium, vanadium, chromium, manganese, cobalt, copper, nickel, gallium, cadmium, indium, silver element, Examples of the metal include palladium, gold, mercury, platinum, tungsten, molybdenum, niobium, osmium, strontium, yttrium, and technetium.

These magnetic iron oxides preferably have a number average particle diameter of 0.05 to 1.0 μm, more preferably 0.1 to 0.5 μm. Magnetic iron oxide having a BET specific surface area of ² to 40 m ² / g (more preferably 4 to ²⁰ m ² / g) is preferably used. There is no restriction | limiting in particular in a shape, The thing of arbitrary shapes is used. As magnetic characteristics, a saturation magnetization is 10 to 200 Am ² / kg (more preferably 70 to 100 Am ² / kg) under a magnetic field of 795.8 kA / m, and a residual magnetization is 1.5 to 25 Am ² / kg (more preferably). 2-20 Am ² / kg) and those having a coercive force of 1-30 kA / m (more preferably 2-15 kA / m) are preferably used.

  In some cases, the magnetic iron oxide used in the magnetic toner of the present invention may be treated with a silane coupling agent, a titanium coupling agent, titanate, aminosilane, or the like.

  The toner of the present invention preferably contains a charge control agent.

  Examples of the toner that controls the negative charge include the following compounds.

  Organic metal complexes and chelate compounds are effective, and examples include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives of bisphenol.

  Among these, an azo metal complex represented by the following formula (I) is preferable.

〔式中、Ｍは配位中心金属を表し、Ｓｃ，Ｔｉ，Ｖ，Ｃｒ，Ｃｏ，Ｎｉ，Ｍｎ又はＦｅ等が挙げられる。Ａｒはアリール基であり、フェニル基、ナフチル基の如きアリール基であり、置換基を有してもよい。この場合の置換基としては、ニトロ基、ハロゲン基、カルボキシル基、アニリド基及び炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシ基がある。Ｘ，Ｘ’，Ｙ及びＹ’は−Ｏ−，−ＣＯ−，−ＮＨ−，−ＮＲ−（Ｒは炭素数１〜４のアルキル基）である。Ｃ⁺はカウンターイオンを示し、水素、ナトリウム、カリウム、アンモニウム、脂肪族アンモニウム或いはそれらの混合イオンを示す。〕

[In the formula, M represents a coordination center metal, and examples thereof include Sc, Ti, V, Cr, Co, Ni, Mn, and Fe. Ar is an aryl group, which is an aryl group such as a phenyl group or a naphthyl group, and may have a substituent. In this case, examples of the substituent include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms, and an alkoxy group having 1 to 18 carbon atoms. X, X ′, Y and Y ′ are —O—, —CO—, —NH—, —NR— (R is an alkyl group having 1 to 4 carbon atoms). C ⁺ represents a counter ion and represents hydrogen, sodium, potassium, ammonium, aliphatic ammonium, or a mixed ion thereof. ]

  In particular, Fe or Cr is preferred as the central metal, halogen, alkyl group or anilide group is preferred as the substituent, and hydrogen, alkali metal, ammonium or aliphatic ammonium is preferred as the counter ion. A mixture of complex salts having different counter ions is also preferably used.

  The following compounds are used to control the toner to be positively charged.

  Nigrosine modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs such as phosphonium salts 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, Ferrocyanide, etc.); metal salt of higher fatty acid; diorganotin oxide such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, di Black hexyl scan such diorgano tin borate such tin borate; guanidine compounds; imidazole compounds. These can be used alone or in combination of two or more. Among these, triphenylmethane compounds and quaternary ammonium salts whose counter ions are not halogen are preferably used. The following formula (II)

〔式中Ｒ₁はＨ又はＣＨ₃を示し、Ｒ₂及びＲ₃は置換または未置換のアルキル基（好ましくは、Ｃ１〜Ｃ４）を示す〕
で表されるモノマーの単重合体；前述したスチレン、アクリル酸エステル、メタクリル酸エステルの如き重合性モノマーとの共重合体を正荷電性制御剤として用いることができる。この場合、この単重合体及び共重合体は荷電制御剤としての機能と、結着樹脂（の全部または一部）としての機能を有する。

[Wherein R ₁ represents H or CH ₃ , and R ₂ and R ₃ represent a substituted or unsubstituted alkyl group (preferably C1 to C4)]
A copolymer with a polymerizable monomer such as styrene, acrylic acid ester or methacrylic acid ester described above can be used as a positive charge control agent. In this case, the homopolymer and copolymer have a function as a charge control agent and a function as a binder resin (all or a part thereof).

  As a method of incorporating a charge control agent into the toner, there are a method of adding it inside the toner particles and a method of adding it externally. 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 limited. Preferably, 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.

  As a method for producing the toner of the present invention, the above-described toner constituent materials are sufficiently mixed by a ball mill or other mixer, and then kneaded well using a heat kneader such as a hot roll kneader or an extruder, and then solidified by cooling. Thereafter, a method of obtaining a toner by mechanically pulverizing with the above-described apparatus and classifying the pulverized powder is preferable. In addition, a polymerization method in which a predetermined material is mixed with a monomer that constitutes the binder resin to obtain an emulsion suspension, followed by polymerization to obtain a toner; a so-called microcapsule toner comprising a core material and a shell material In which a predetermined material is contained in the core material, the shell material, or both of them; and a method of obtaining the toner by dispersing the constituent materials in the binder resin solution and then spray-drying. Further, the toner of the present invention can be produced by sufficiently mixing the desired additive and toner particles with a mixer using the various methods described above as required.

  For example, as a mixer, Henschel mixer (Mitsui Mining Co., Ltd.); Super mixer (Kawata Co., Ltd.); Ribocorn (Okawara Seisakusho Co., Ltd.); (Manufactured by Taiheiyo Kiko Co., Ltd.); Ladige mixer (manufactured by Matsubo Co., Ltd.), and kneading machines such as KRC kneader (manufactured by Kurimoto Iron Works); (Manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Works); PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); Mining company); MS pressure kneader, Nider Ruder (Moriyama Seisakusho); Banbury mixer (Kobe Steel) As classifiers, classifiers, micron classifiers, spedic classifiers (manufactured by Seishin Enterprises); turbo classifiers (manufactured by Nissin Engineering); micron separators, turboplex (ATP), TSP separators (Hosokawa Micron) Elbow Jet (manufactured by Nippon Steel & Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Kogyo Co., Ltd.); YM Microcut (manufactured by Yaskawa Shoji Co., Ltd.), and sieves used for sieving coarse particles Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (manufactured by Deoksugakusho Co., Ltd.); Vibrasonic System (manufactured by Dalton Co.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Manufactured by Kogyo Co., Ltd.); Micro shifter Makino Sangyo); circular vibration sieve, and the like.

  The toner according to the present invention preferably has at least two kinds of inorganic fine powders supported on the surface, and those having an average particle diameter of 5 nm to 25 nm (inorganic fine powder A) and an average particle diameter of 30 nm or more. It is preferably 3 μm or less (inorganic fine powder B).

  The inorganic fine powder A having an average particle size of 5 nm or more and 25 nm or less acts as a fluidizing agent. When toner particle fluidity is insufficient, toner movement at the contact area between the photosensitive drum and the developing sleeve is insufficient, and variation in the frictional charge amount of each magnetic spike tends to increase. There are many. When the average particle size of the inorganic fine powder A exceeds 25 nm, sufficient fluidity cannot be imparted to the toner. In addition, when the average primary particle size of the inorganic fine powder A is smaller than 5 nm, the cohesiveness of the inorganic fine powder is increased, and the particle size distribution having a strong cohesiveness that is difficult to be solved by the pulverization treatment instead of the primary particles is wide. It tends to behave as an agglomerate and cannot give sufficient fluidity, and also tends to cause image defects by damaging the photosensitive drum or the developing sleeve.

  On the other hand, the inorganic fine powder B having an average particle size of 30 nm or more and 3 μm or less acts as a spacer between the toner particles in addition to preventing embedding of the inorganic fine powder A and as a transfer aid. In the contact development method, the toner particles rub against each other at the contact portion between the photosensitive drum and the developing sleeve, but positively charged particles and oppositely charged particles tend to be generated by frictional charging between the particles. If reverse polarity charged toner is generated by frictional charging between toner particles, fogging and transferability deteriorate. Furthermore, in a cleanerless system, it directly leads to contamination of the charging member. However, since the inorganic fine powder B acts as a spacer, direct rubbing between the toner particles is avoided, so that the generation of reverse polarity charged toner can be suppressed and such problems can be prevented.

  If the average particle size of the inorganic fine powder B is less than 30 nm, it is difficult to avoid direct contact between the toner particles. On the other hand, if it exceeds 3 μm, the toner particles are easily released from the surface, and the effect is hardly obtained.

  A more preferable range is 40 nm or more and 1 μm or less, and 40 nm or more and 0.5 μm or less is more preferable.

  Thus, the effect of using two or more kinds of inorganic fine powders having different average particle diameters appears to be particularly noticeable in the magnetic contact development method.

Here, the addition amount Aa of the inorganic fine powder A and the addition amount Bb of the inorganic fine powder B to the toner are:
0.5 ≦ Aa / Bb ≦ 10
It is preferable that the relationship be When Aa / Bb <0.5, the effect of the inorganic fine powder A as a fluidizing agent is insufficient, and there is a case where roughness is observed. When 10 <Aa / Bb, the effect of additive B may be insufficient, and in a cleanerless system, there is a possibility that fogging is deteriorated due to contamination of the charging member as well as durability.

  In the present invention, the measurement method of the average primary particle size of the inorganic fine powder is a photograph of the toner magnified by a scanning electron microscope, and the inorganic fine powder is further analyzed by an elemental analysis means such as XMA attached to the scanning electron microscope. While contrasting the photograph of the toner mapped with the contained element, 100 or more primary particles of the inorganic fine powder that are attached to or separated from the toner surface can be measured to obtain the number average particle diameter.

  The inorganic fine powder A is desirably at least one selected from silica, titanium oxide, and alumina. This is because fluidity is easily imparted to the toner due to the shape of the powder and the frictional charging characteristics.

For example, in the case of silica, so-called fine silicate powder, so-called wet silica produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass, etc. Both can be used, but dry silica is preferred because it has few silanol groups on the surface and in the silica fine powder, and few production residues such as Na ₂ O and SO ³⁻ . 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.

  Such an inorganic fine powder A is preferably used after being hydrophobized in view of characteristics in a high temperature and high humidity environment. When the inorganic fine powder mixed with the toner absorbs moisture, the triboelectric charge amount of the toner is remarkably reduced, and the toner is likely to scatter.

  As treatment agents for hydrophobizing 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 You may process together.

  Among these, those treated with silicone oil are preferable, and more preferably, the inorganic fine powder is treated with silicone oil at the same time or after hydrophobizing with a silane compound, and then treated with silicone oil. It is good for keeping the amount high and preventing toner scattering.

  The conditions for hydrophobizing the inorganic fine powder are as follows. For example, a silylation reaction is performed with a silane compound as a first-stage reaction, and silanol groups are eliminated by chemical bonding, and then a hydrophobic thin film is formed on the surface with silicone oil as a second-stage reaction.

The silicone oil preferably has a viscosity at 25 ° C. of 10 to 200,000 mm ² / s, and more preferably 3,000 to 80,000 mm ² / s. If it is less than 10 mm ² / s, the inorganic fine powder is not stable and the image quality tends to deteriorate due to heat and mechanical stress. If it exceeds 200,000 mm ² / s, uniform processing tends to be difficult.

  As the silicone oil used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like are particularly preferable.

  As a method for treating the silicone oil, for example, the inorganic fine powder treated with the silane compound and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the silicone oil is sprayed onto the inorganic fine powder. A method may be used.

  Alternatively, after dissolving or dispersing silicone oil in an appropriate solvent, inorganic fine powder may be added and mixed to remove the solvent. A method using a sprayer is more preferable in that the formation of inorganic fine powder aggregates is relatively small.

  The treatment amount of the silicone oil is 1 to 23 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of the inorganic fine powder. If the amount of silicone oil is too small, good hydrophobicity cannot be obtained, and if it is too large, problems such as fogging occur.

  The addition amounts of the inorganic fine powders A and B are each preferably 0.1 to 3.0% by mass with respect to the toner. If the addition amount is less than 0.1% by mass, the effect is not sufficient, and if it exceeds 3.0% by mass, the fixing property is deteriorated.

  In addition to the inorganic fine powders A and B, the toner according to the present invention is also preferably used by adding conductive fine particles. The charge exchange between the magnetic spikes is promoted, and the variation in the triboelectric charge amount is further improved.

The volume resistance of the conductive fine particles is preferably 1 × 10 ⁻¹ to 1 × 10 ⁹ Ωcm. If it is less than 1 × 10 ⁻¹ Ωcm, there is a concern that the triboelectric charge amount may be lowered under high humidity. On the other hand, if it exceeds 1 × 10 ⁹ Ωcm, the effect of promoting charge exchange is low.

The conductive fine particles preferably have a volume-based median diameter (D ₅₀ ; unit μm) of 0.4 μm or more and 4.0 μm or less and less than the weight average particle diameter of the toner. In general, the greater the difference in particle size between particles, the stronger the adhesive force due to the interaction between particles. One of the actions of the conductive fine particles in the present invention is to improve the tribocharging property by contact with the toner particles forming the magnetic spike, and strong adhesion to the toner particles is not preferable. The appropriate D ₅₀ of the conductive fine particles capable of interacting with a large number of toner particles is 0.4 μm or more. Metal compound fine particles having a D ₅₀ of less than 0.4 μm are likely to adhere to one toner particle, and improvement in the triboelectric charging characteristics due to charge exchange between the magnetic spikes cannot be expected.

On the other hand, the interaction between the toner when D ₅₀ is increased is weakened, the effect of improving the friction charging properties reduced. If the D _{50 of the} conductive fine particles exceeds 4.0 μm, it is difficult to obtain the effect due to charge exchange, and in addition, it acts as an electrode under the development electric field, which rather hinders toner movement. , Fog is deteriorated and resolution is lowered. Therefore, it is preferably 4.0 μm or less, and more preferably less than the mass average particle diameter of the toner. For this reason, it is necessary to reduce the number of particles having a large particle diameter. If D ₁₀ and D ₉₀ on a volume basis are used as an index of particle size distribution, D ₉₀ is preferably 6.0 μm or less.

In addition, it is more preferable if D ₁₀ is less than 3.5 μm. Further, as described above, in the particle size distribution of the conductive fine particles, it is preferable that the number of particles having very small particle diameter is small, and D ₁₀ is preferably 0.3 μm or more.

  Such conductive fine particles are usually used in an addition amount of 0.1% by mass or more and 3.0% by mass or less based on the whole toner.

Here, D ₁₀ , D ₅₀ , and D ₉₀ of the conductive fine particles are measured as follows.

  A liquid module is attached to a laser diffraction type particle size distribution measuring apparatus “LS-230 type” (manufactured by Coulter), and a particle size of 0.04 to 2000 μm is set as a measurement range, and D10 and D50 of particles are obtained by a volume-based particle size distribution obtained. , D90 is calculated. In the measurement, about 10 mg of particles are added to 10 ml of methanol and dispersed for 2 minutes with an ultrasonic disperser, and then measured under the conditions of a measurement time of 90 seconds and a single measurement.

  It is also preferable from the viewpoint of controlling hygroscopicity under high humidity that the conductive fine particles are used after being subjected to an appropriate surface treatment. As the treatment agent for the surface treatment, one having water repellency such as a silicon compound is preferable.

  As an apparatus for the addition treatment of inorganic fine powder or conductive fine particles, for example, Henschel mixer (manufactured by Mitsui Mining); Super mixer (manufactured by Kawata); Ribocorn (manufactured by Okawara Seisakusho); Nauter mixer, turbulizer, Cyclomix (manufactured by Hosokawa Micron Corporation); spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.);

  Hereinafter, the present invention will be specifically described with reference to production examples and examples, but this does not limit the present invention in any way. In the following formulation, all parts are parts by mass.

[Toner Production Example 1]
Material composition / binder resin 100 parts (styrene-acrylic resin (glass transition temperature Tg by DSC measurement is 58 ° C., acid value 23.0 mg KOH / g, MPC by GPC (number average molecular weight) 7000, Mw (weight average molecular weight) 450,000) Monomer ratio: 72.5 parts of styrene, 20 parts of n-butyl acrylate, 7 parts of mono-n-butyl malate, 0.6 parts of divinylbenzene))
Magnetic iron oxide 95 parts (average particle size: 0.20 μm, BET specific surface area: 8.0 m ² / g, coercive force: 5.2 kA / m, saturation magnetization: 83.6 Am ² / kg, residual magnetization: 6. 0 Am ² / kg)
Polypropylene wax 4 parts (melting point 143 ° C, penetration at 25 ° C 0.5 mm)
Charge control agent 2 parts (iron complex of azo compound (I); where X = X ′ = Y = Y ′ = O, Ar is a naphthyl group having an anilide group as a substituent, C ⁺ is a hydrogen ion or an ammonium ion Each represents a mixture)
The above compound was melt-kneaded with a biaxial extruder heated to 130 ° C., and the cooled kneaded product was coarsely pulverized with a hammer mill. Subsequent fine grinding was performed by mechanical grinding using a turbo mill (manufactured by Turbo Kogyo Co., Ltd.). The resulting finely pulverized product was subjected to strict classification and removal of ultrafine powder and coarse powder with a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to obtain black powder.

next,
-100 parts of the above black powder-Silica with a primary particle size of 8 nm (hydrophobized with dimethyl silicone oil and hexamethyldisilazane, BET 120 m ² / g) 0.8 part-Silica with a primary particle size of 50 nm (hexamethyl 0.5 parts of BET 40 m ² / g surface-treated with disilazane) The above materials were mixed for 90 seconds with a Henschel mixer FM10C / l (manufactured by Mitsui Mining Co., Ltd.) to obtain toner 1. Table 1 shows various physical properties of Toner 1 thus obtained.

<Example 1>
As the schematic configuration of the image forming apparatus of this embodiment, the one shown in FIG. 1 was used.

  As the photosensitive drum 1, a rotating drum type negative-polarity OPC photosensitive drum having a diameter of 24 mm was used. The photosensitive drum 1 is rotationally driven in a clockwise direction indicated by an arrow at a constant speed of 85 mm / sec (= process speed PS, printing speed).

  As the contact member 22, a 100 μm polyimide film is used and is in contact with the charging roller at a linear pressure of 10 (N / m) or less. Polyimide was used because it has a triboelectric charge property that gives a negative charge to the toner.

  As a charging bias from S1, a DC voltage of -1300V is applied, and the surface of the photosensitive drum 1 is uniformly contact-charged to a charging potential (dark portion potential) of -700V.

  In the present embodiment, when the uniformly charged surface of the photosensitive drum 1 is exposed entirely with laser light, the laser power is adjusted so that the potential of the photosensitive drum surface becomes −150V.

As the transfer roller 5, one having a roller resistance value of 5 × 10 ⁸ Ω was used, and transfer was performed by applying a voltage of +2.0 kV to the cored bar 5b.

  The pressure between the photosensitive drum and the developing sleeve was adjusted to 200 N / m by the drawing pressure.

The developing sleeve 440 was formed by bonding a conductive elastic layer having a thickness of 500 μm on the aluminum sleeve 442b and polishing. The micro hardness was 90 degrees, and the surface roughness was 3.8 μm in Rz and 0.6 μm in Ra.

  Further, a developing bias voltage in which 1.2 kHz, a rectangular wave, and Vpp 300 V are superimposed is applied as an AC voltage to a DC voltage of −350 V from the developing bias applying power source S2 to the sleeve 440.

  Further, in this experiment, the developing sleeve is driven at a circumferential speed of 1.20 times that of the photosensitive drum.

In this embodiment, toner 1 is used as the magnetic toner, and in order to obtain a desired toner coat amount in the developing device, the regulating blade 420 is set to a drawing pressure of about 50 (N / m) and a blade free length of about 0.5 mm. Yes. As a result, the toner coat amount M is controlled to 14.0 g / m ² .

The developing device is filled with 100 g of toner 1, and under an ordinary temperature and low humidity (20 ° C./10%), an image pattern consisting of only a horizontal line with a printing area ratio of about 1% is intermittently printed on one sheet, and a durability test is performed. went. As a transfer material, A4 copy paper of 75 g / m ² was used.

Evaluation Method of Each Example and Comparative Example The following various image evaluations a) to e) were performed after printing 1000 sheets. Only measurement f) was performed after printing 100 sheets from the initial stage.

a) Evaluation of fogging The fogging on paper was measured using a REFECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. A green filter was used as the filter. The fog value was calculated from the following formula using a solid white image. If the fog on paper is 2.0% or less, a good image is obtained.
Fog (reflectance) (%) = reflectance on standard paper (%) − reflectance of sample non-image area (%)

  In addition, when other image defects described below occur, the measurement was performed while avoiding the location, and consideration was given so that the fog can be evaluated purely.

b) Image Density A solid black image that prints black on the entire surface was output, and the optical reflection density was measured with a densitometer RD-1255 manufactured by Macbeth. There is no problem if the image density is 1.3 or more.

c) Roughness The roughness was evaluated by using a 600 dpi laser scanner and outputting a halftone image from the number of defects in the image. In this evaluation, a halftone image means a striped pattern in which one line in the main scanning direction is recorded and then two lines are not recorded, and expresses a halftone density as a whole.

In the present invention, one line in the halftone image is selected and evaluated by the number of defects of 0.2 mm or more.
X: Five or more defects having a diameter of 0.2 mm or more exist in one line of the halftone image.
Δ: One to four defects having a diameter of 0.2 mm or more exist in one line of the halftone image.
○: There is no defect having a diameter of 0.2 mm or more in one line of the halftone image.

d) Solid White Image Defect Image evaluation was performed on image defects caused by a developing sleeve or a developing roller cycle in solid white. The development cycle was accurately calculated in consideration of the process speed and the peripheral speed ratio between the photosensitive drum and the developing sleeve, and image defects having the same cycle were extracted and evaluated. The size of the image defect is about 2 to 3 mm in the short axis length, about 3 to 10 mm in the long axis length, and the partial optical density is about 0.3 to 1, which is evaluated separately from other image defects. . The evaluation can be clearly discriminated with and without defects, and was evaluated according to the following criteria.
×: Image defect present ○: Image defect absent

  The evaluation was performed by continuously printing about 20 solid white images.

e) Uncollected ghost The uncollected ghost was evaluated with a halftone image in which a 20 mm square patch image was printed at the tip. Taking into account the peripheral speed and process speed of the photosensitive drum, measure the image density of the ghost image corresponding part that appears in the photosensitive drum cycle and the image density of the other halftone parts in the image halftone part, and obtain the difference between the two. It was. The better the recoverability, the smaller the difference between the two. Further, when the density difference between the two exceeds 0.20, the ghost image becomes remarkable, which causes a problem in practical use.

f) Measurement of the toner coat amount M on the developing roller For the measurement of the toner coat amount on the developing sleeve or the developing roller, a suction device generally configured as shown in FIG. 2 was used. The toner is sucked while pressing the suction port m1 against the developing roller, and the toner is collected in the filter m2 of the inner cylinder. At this time, the inner cylinder is insulative and is connected to the ground to prevent toner scattering due to static electricity. The mass m of the sucked developer is calculated from the increase in the mass of the filter, and the sucked area: s (m ² ) is also measured. At this time, the coating amount M (g / m ² ) of the developer on the sleeve is obtained from m / s. The measurement was performed for the toner on the developing roller before development by stopping the recording apparatus main body during solid white printing.

  The results for toner 1 are shown in Table 2. As can be seen from the table, good results were obtained.

<Examples 2 and 3 and Comparative Examples 1 and 2>
The same evaluation as in Example 1 was performed by using the toner 1 and appropriately changing the toner coating amount M by adjusting the drawing pressure of the regulating blade 420 and the blade free length. The results are shown in Table 2.

[Toner Production Example 2]
In Toner Production Example 1, the magnetic iron oxide used has a residual magnetization of 3.0 Am ² / kg, which is changed to 50 parts, and as an external additive, 0.95 parts of surface-treated silica having a primary particle diameter of 8 nm and a primary particle diameter of 50 nm are used. Toner 2 was obtained using 0.6 part of the surface-treated silica.

[Toner Production Example 3]
In Toner Production Example 1, toner 3 was obtained using magnetic iron oxide having a residual magnetization of 12.7 Am ² / kg.

[Toner Production Example 4]
In Toner Production Example 1, the magnetic iron oxide used has a remanent magnetization of 3.0 Am ² / kg and is changed to 40 parts. As an external additive, 1.0 part of surface-treated silica having a primary particle diameter of 8 nm and a primary particle diameter of 50 nm are used. Toner 4 was obtained using 0.6 part of the surface-treated silica.

[Toner Production Example 5]
In toner production example 1, toner 5 was obtained using magnetic iron oxide having a residual magnetization of 15.1 Am ² / kg.

[Toner Production Example 6]
In Toner Production Example 1, toner 6 was obtained using magnetic iron oxide having a residual magnetization of 7.0 Am ² / kg.

[Toner Production Example 7]
In the same manner as in Toner Production Example 6, melt-kneading was performed using magnetic iron oxide having a remanent magnetization of 7.0 Am ² / kg, and the kneaded product was coarsely pulverized with a hammer mill. This coarsely pulverized product was finely pulverized with a jet mill, and the fine powder and coarse powder were strictly classified and removed with a multi-division classifier in the same manner as in Toner Production Example 1 to obtain a black powder. Thereafter, external addition treatment was performed in the same manner as in Toner Production Example 1 to obtain Toner 7.

[Toner Production Example 8]
After subjecting the finely pulverized powder obtained in Toner Production Example 7 to surface modification by mechanical impact force, super fine powder and coarse powder are strictly classified and removed using a multi-division classifier as in Toner Production Example 7. As a result, black powder was obtained. Thereafter, an external addition treatment was performed in the same manner as in Toner Production Example 7 to obtain Toner 8.

[Toner Production Example 9]
The finely pulverized product obtained in the same manner as in Toner Production Example 6 was subjected to surface modification by mechanical impact force, and then super fine powder and coarse powder were strictly classified and removed to obtain black powder. Thereafter, external addition was performed in the same manner as in Toner Production Example 6 to obtain Toner 9.

[Toner Production Example 10]
In Toner Production Example 2, the fine pulverization conditions and classification conditions were changed to obtain black powder. Thereafter, toner 10 was obtained using 2.0 parts of surface-treated silica having a primary particle diameter of 8 nm and 1.0 part of surface-treated silica having a primary particle diameter of 50 nm as external additives.

[Toner Production Example 11]
In Toner Production Example 3, fine powders and classification conditions were changed to obtain black powder. Thereafter, toner 11 was obtained using 0.5 parts of surface-treated silica having a primary particle diameter of 8 nm and 0.3 part of surface-treated silica having a primary particle diameter of 50 nm as external additives.

[Toner Production Examples 12 to 16]
Toners 12 to 16 were obtained by changing the external addition conditions for the black powder obtained in Toner Production Example 1.

  Table 1 shows external addition conditions and powder physical properties of the toners 2 to 16.

<Examples 4 to 15>
The same evaluation as in Example 1 was performed using toners 2, 3, 6, 8 to 16. The results are shown in Table 2.

<Comparative Examples 3 and 4>
The same evaluation as in Example 1 was performed by using toners 2 and 3 and appropriately changing M / σr by adjusting the drawing pressure of the regulating blade 420 and the blade free length. The results are shown in Table 2.

<Comparative Examples 5 to 7>
The same evaluation as in Example 1 was performed using toners 4, 5, and 7. The results are shown in Table 2.

As can be seen from the results of Examples 1 and 2 and Comparative Example 1 in Table 2, in this system, the image density is insufficient when the toner coat amount M is less than 5.0 g / m ² . On the other hand, as can be seen from Examples 1, 3, 4, 6 and Comparative Example 2, when M exceeds 16.0 g / m ² , the image roughness and solid white image defects are conspicuous. M is should be controlled below 5.0 g / m ² or more 16.0 g / m ^2, coarseness if 15 g / m ² or less is better.

  From the results of Examples 8, 9, 10 and Comparative Example 7, the average circularity of the toner in this system needs to be 0.945 or more, more preferably 0.950 or more, and more preferably 0.955 or more. preferable.

From the results of Examples 1, 4, 5, 6, 7, and Comparative Examples 5 and 6, when the residual magnetization σr of the toner in this system is less than 1.0 Am ² / kg, fogging and poor recovery ghost are observed. If it exceeds 6.0 Am ² / kg, in addition to a decrease in the image density, a roughness or solid white image defect is observed.

  Further, from the results of Examples 1, 4, 5, and 7 and Comparative Examples 3 and 4, the image density is insufficient when M / σr is less than 1.4 in this system. A ghost is seen.

  Further, when the weight average particle diameter of the toner is D4 (μm), if M / (σr × D4) is 0.14 or more in this system, the image density is not a problem. If it exceeds 4.0, it can be seen that fog and poorly recovered ghosts are slightly worse at a level that does not cause a problem.

  From the results of Examples 1 and 11 to 15, the toner according to this system carries on the surface at least two kinds of inorganic fine powders having an average particle size of 5 nm to 25 nm and an average particle size of 25 nm to 3 μm. If the average particle size is 5 nm or more and 25 nm or less is one selected from silica, titanium oxide, and alumina, good image characteristics can be obtained.

  In addition, a more preferable result is obtained when the particles having an average particle diameter of 5 nm or more and 25 nm or less are subjected to a hydrophobic treatment.

[Reference toner production example 1]
In Toner Production Example 1, the addition amount of silica having a primary particle diameter of 8 nm was changed to 0.8 part, and the addition amount of silica having a primary particle diameter of 50 nm was changed to 1.6 parts, whereby Reference toner 1 was obtained. Various physical properties of the obtained reference toner 1 are shown in Table 3.

[Reference toner production examples 2 to 7]
Reference toners 2 to 7 were obtained by changing the addition amount of silica or the primary particle size. Table 3 shows the physical properties of the obtained reference toners 2 to 7.

[Reference toner production example 8]
In Toner Production Example 1, in addition to two types of silica, D ₁₀ , D ₅₀ , and D ₉₀ as conductive fine particles A are 0.3 μm, 0.4 μm, and 0.9 μm, respectively, and the surface is amino-modified silicone. 1.0 part of oxygen-deficient tin oxide (resistance 1 × 10 ³ Ωcm) treated with oil was added to obtain reference toner 8. Table 3 shows properties of the obtained reference toner 8.

[Reference toner production examples 9, 10]
Reference toners 9 and 10 were obtained by adding conductive fine particles having a changed particle size and / or surface treatment agent in Reference toner production example 8. Table 3 shows various physical properties of the obtained reference toners 9 and 10.

<Reference Example 1>
An apparatus similar to that of Example 1 was prepared. This development device is filled with 80g of toner 1, and at 23 ° C / 5% temperature and humidity, 1,000 image patterns consisting only of horizontal lines with a printing area ratio of about 0.5% are printed intermittently, and the durability test is performed. Went.

  The evaluation method for each image evaluation is the same as in Example 1. However, regarding the evaluation of the solid white image defect, the evaluation was performed after continuously printing about 100 solid white images.

  The results are shown in Table 4. As can be seen from Table 4, satisfactory results were obtained.

<Reference Examples 2 to 13>
Image evaluation was performed under the same conditions as in Reference Example 1 using toners 12 and 14 and reference toners 1 to 10. The results are shown in Table 4.

  From Reference Examples 1 to 13, it can be seen that, in a cleanerless system under severe conditions in a low-humidity environment, the toner according to the present invention exhibits a satisfactory durability.

  Moreover, the following is understood from the reference example table.

  As the additive amount ratio of inorganic fine powders A and B and Aa / Bb become smaller, the roughness becomes worse, but there is no problem if Aa / Bb is 0.5 or more. Conversely, when Aa / Bb increases, the poor recovery ghost after durability tends to deteriorate, but there is no problem if Aa / Bb is 10 or less.

  When the particle size of the inorganic fine powder B is small, deterioration in the image density and fog after the endurance tends to be seen, but if it is 30 nm or more, there is no problem. On the other hand, when it increases, the effect of addition decreases, but if it is 3 μm or less, the effect is seen, and if it is 1 μm or less, the effect clearly appears, and if it is 500 nm or less, a more preferable effect is obtained.

Furthermore, image characteristics are improved by adding conductive fine particles surface-treated with a silicon compound. When the particle size of the conductive fine particles is too small or too large, the effect of addition is small, but D ₁₀ , D ₅₀ , D ₉₀ are 0.3 μm, 0.4 μm, 0.9 μm or more, and 3.5 μm, respectively. If it is 4.0 μm or less than 6.0 μm, the effect of addition is surely seen.

<Examples 16 to 19>
Development sleeves were prepared in which the thickness of the elastic layer was changed to 20 μm, 50 μm, 2000 μm, and 4000 μm, and other evaluations were performed under the same conditions as in Example 1. However, the durability test was not performed, and the image characteristics were evaluated only after printing 100 sheets from the initial stage.

  The results are shown in Table 5.

  When the thickness of the elastic layer was less than 50 μm, slight roughness was generated, and very small black spots due to scratches on the photosensitive drum were observed on the solid white image. On the other hand, when it exceeded 2000 μm, the image density seemed to be lowered, and fogging and poor recovery ghost were slightly observed. However, there is no practical problem in either case.

<Examples 20 to 23>
A developing sleeve in which the microhardness of the elastic layer was changed to 10, 40, 95, and 200 was prepared, and a developing device was prepared with the same settings as in Example 1. The developing apparatus was left for 1 week under the condition of 40 ° C., and then 100 sheets were printed under the same conditions as in Example 1, and the same evaluation was performed.

  The results are shown in Table 6.

  When the microhardness of the elastic layer was less than 40, in addition to the slight roughness, set marks that appeared to be generated between the developing sleeve and the photosensitive drum and between the developing sleeve and the regulating blade were slightly generated on the image. On the other hand, when it exceeded 95, a very small black spot was seen on the solid white image, and a slight density difference was generated on the left and right on the other images. However, there is no practical problem in either case.

<Example 24>
In Example 18, the same evaluation as in Example 18 was performed using only a DC voltage of −350 V as the developing bias applied to the sleeve 60a. The results are shown in Table 7.

  Compared with the case where only the DC voltage is used as the developing bias, the use of the AC voltage superimposed is somewhat advantageous in terms of fog, image density, and roughness. The recoverability in the cleanerless system was also somewhat advantageous. However, there is no practical problem even when only the DC voltage is used.

1 is a schematic configuration diagram of an image forming apparatus used in the present embodiment. It is a developer amount measurement tool diagram in the present invention. 1 is a schematic configuration diagram of a specific example of an electrophotographic cartridge of the present invention.

Explanation of symbols

1 Photosensitive drum (developer)
2 Charging member 21 Charging roller 22 Contact member 3 Exposure device 400 Development device 410 Toner, t
420 Regulating blade 430 Stirring member 440 Developing roll 442a Elastic layer 442b Aluminum cylinder 442c Magnet roll 450 Developing container 5 Transfer member 5a Middle resistance layer 5b Core metal 6 Fixing device a Developing nip portion b Transfer nip portion n Charging portion P Transfer material m1 Suction M2 filter

Claims (14)

Using a developer carrying member having an elastic layer on the surface and has a magnetic field generating means fixed inside attract toner having magnetic by the magnetic field generating means of the fixed developer carrying member surface, the developer amount regulating means electrostatic the developer amount M on the developer carrying member surface 5.0 g / m ² or more 16.0 g / m ² regulated below were formed on the developing member by a static-unit and the image exposure means by A magnetic contact developing method comprising at least a step of developing a latent image while pressing and rotating the developer carrying member against a developing member;
The average circularity of the magnetic toner is 0.945 or more,
When the residual magnetization of the magnetic toner is σr (Am ² / kg), 1.0 ≦ σr ≦ 6.0
And
1.4 ≦ M / σr ≦ 15
A magnetic contact development method characterized by the above. 2. The developing process according to claim 1, wherein in the developing step, the moving speed of the surface of the developer carrying member in the pressing area is 1.01 to 2.00 times the moving speed of the surface of the developing object. Development method. When the weight average particle diameter of the magnetic toner is D4 (μm), 0.14 ≦ M / (σr × D4) ≦ 4.0
The developing method according to claim 1, wherein: Developing method according to any one of claims 1 to 3, wherein the average circularity of the magnetic toner is 0.950 or more. The surface of the magnetic toner, at least an average particle diameter of 5nm or more 25nm average particle size below the inorganic fine powder A is of Claims 1 to 4, characterized in that it carries a 3μm following inorganic fine powder B or 30nm The developing method according to any one of the above. 6. The developing method according to claim 5 , wherein the inorganic fine powder A is at least one selected from silica, titanium oxide, and alumina. The developing method according to claim 5 or 6 , wherein the inorganic fine powder A is hydrophobized. A developing step of developing an electrostatic latent image formed on the developing member by applying a developing bias between the developer carrying member and the developing member to transfer the magnetic toner onto the developing member. in developing method according to any one of claims 1 to 7 developing bias is equal to or is obtained by superimposing a DC voltage to an alternating voltage. A charging step in which at least a charging member is brought into contact with the developing member and charging is performed by applying a voltage from the outside, an exposure step in which an electrostatic latent image is formed on the developing member by irradiation of light energy, and the like. In an image forming method comprising: a developing step for developing and visualizing a development target holding a latent image on a surface with a developer; and a transfer step for transferring the developer developed on the development target to a transfer material. image forming method characterized by developing step is carried out in one of the developing method according to claim 1 to 8. The image forming method according to claim 9 , wherein the developing step also serves as a cleaning step of collecting the developer remaining on the developing target after the transfer step. Developing device for developing in one of the developing method according to claim 1 to 8. The developing member to form an electrostatic latent image, a charging device for charging the該被developing member, the electrophotographic cartridge formed integrally made from a developing apparatus for developing the electrostatic latent image, developing device according to claim 11 An electrophotographic cartridge, which is the developing device described in 1. The developing member to form an electrostatic latent image, a charging device for charging the該被developing member, the electrophotographic cartridge formed integrally made of a developing device for developing the electrostatic latent image, developing device according to claim 11 And an untransferred developer remaining on the development target is collected by the developing device. A transfer device that removably equips the electrophotographic cartridge according to claim 12 or 13 and that transfers a developer image formed on the development target onto a transfer material, and a developer image on the transfer material. An electrophotographic image forming apparatus comprising a fixing device for fixing on a transfer material.

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