JP2013148813A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of reducing density unevenness while suppressing poor cleaning, and an image forming apparatus including the developing device.SOLUTION: A developing device 7 includes on the surface of a developing sleeve 15 provided in a rotatable manner a developer carrier 12 for carrying a developer containing a toner with a fatty acid metal salt externally added thereto. The developing sleeve 15 includes a base material that is covered with a surface layer formed of a material having adhesive force with the toner smaller than that of the base material.

Description

  The present invention relates to a developing device used in an image forming apparatus such as a printer, a facsimile machine, and a copying machine, and an image forming apparatus provided with the developing device.

  In an image forming apparatus, an image is generally formed by the following process. That is, first, a latent image is formed by optically scanning a photoreceptor, which is an image carrier uniformly charged by a charging device, and the latent image is developed by a developing device using a developer containing toner. . Next, the toner image obtained by the development is directly transferred from the photosensitive member to a transfer sheet as a recording medium, or transferred to the transfer sheet via an intermediate transfer member. Some amount of untransferred toner adheres to the surface of the photoreceptor after the transfer. This transfer residual toner is removed from the surface of the photoreceptor by a cleaning device including a cleaning member such as a cleaning blade.

  With the recent increase in image quality, the toner used for image formation tends to have a smaller particle size and a circular shape, so that it is easier for the toner to slip between the photoconductor and the cleaning blade, resulting in poor cleaning. May occur. Patent Document 1 discloses that the above-described poor cleaning can be suppressed by externally adding zinc stearate, which is a fatty acid metal salt, to a toner.

  As the developing device, a developing device using a two-component developer containing toner and a magnetic carrier is known. In this developing device, a magnetic field generating means is provided inside a developing sleeve forming a developing roller that is a developer carrying member, and a magnetic brush is formed by causing the developer to stand on the surface of the developing sleeve by the magnetic field generated by the magnetic field generating means. Let In the developing region where the developing roller and the photosensitive member are close to each other, a developing electric field is generated by a potential difference between the developing sleeve to which a developing bias having the same polarity as the toner charging polarity is applied and the latent image formed on the surface of the photosensitive member. The toner in the developer forming the magnetic brush is transferred to the latent image. As a result, the developing device develops the latent image on the surface of the photoreceptor, and a toner image is formed on the surface of the photoreceptor.

  In the developing device using the two-component developer, density unevenness may occur in the developed toner image due to “developing sleeve surface contamination” in which toner directly adheres to the surface of the developing sleeve. Regarding the problem of density unevenness, first, “developing sleeve surface contamination” that causes the problem will be described.

  When the developing sleeve transports the developer, the developer is transported while moving relative to the developing sleeve. More specifically, the magnetic brush of the developer on the surface of the developing sleeve is brought into a sprouting state or a lying state by the magnetic field generated by the magnetic field generating means. Since the developer is transported on the surface of the developing sleeve while repeating the state where the magnetic brush is standing up or sleeping, the change from the standing state to the sleeping state, or the rising state from the sleeping state An impact is applied to the developer forming the magnetic brush at the timing of change to. Due to this impact, the toner may leave the carrier and adhere directly to the surface of the developing sleeve, which becomes the developing sleeve surface contamination.

  The toner is charged with a predetermined polarity (hereinafter referred to as a negative polarity but may be a positive polarity as an example) due to frictional charging with the carrier before being carried as a developer on the developing sleeve. The toner forming the toner also has a negative polarity charge. A developing bias having the same polarity (negative polarity) as the charging polarity of the toner is applied to the developing sleeve. However, in the portion where the surface of the developing sleeve is soiled, the developing sleeve apparently appears due to the negative charge of the toner. Potential increases to negative polarity. For this reason, the developing sleeve surface contamination occurs, and the electric field strength of the developing electric field is higher in the developing region in the portion where the toner adheres to the surface of the developing sleeve than in other portions. Therefore, in the portion where the toner is attached to the surface of the developing sleeve, more toner is transferred to the latent image of the photosensitive member, and is not attached to the portion where the toner is attached on the surface of the developing sleeve. Density unevenness occurs between the areas.

  As a result of extensive studies by the inventors of the present application, it has been found that the density unevenness may be deteriorated when a developer containing a toner externally added with a fatty acid metal salt such as zinc stearate is used.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device capable of reducing density unevenness while suppressing poor cleaning, and an image forming apparatus including the developing device.

  In order to achieve the above object, the invention according to claim 1 comprises a developer carrying body carrying a developer containing toner to which a fatty acid metal salt is externally added on the surface of a developing sleeve that is rotatably provided. In the developing device, the developing sleeve is formed by coating the base material of the developing sleeve with a surface layer made of a substance having a smaller adhesion force to the toner than the base material.

  In the present invention, a developing sleeve is used in which a surface layer made of a material having a smaller adhesion force to toner than the base material of the developing sleeve is coated on the base material, so that the base material is not coated with the surface layer. The adhesion force generated between the developing sleeve surface and the toner can be reduced. As a result, it becomes difficult for the toner to adhere to the surface of the developing sleeve, and accordingly, the surface of the developing sleeve can be prevented from becoming dirty. Therefore, it is possible to suppress the occurrence of density unevenness between the portion where the toner is attached and the portion where the toner is not attached on the surface of the developing sleeve as described above. Further, as clarified in an experiment to be described later, even when a toner externally added with a fatty acid metal salt is used, the density unevenness can be reduced by covering the base material with the surface layer as a developing sleeve. it can.

  As described above, according to the present invention, there is an excellent effect that density unevenness can be reduced while suppressing poor cleaning.

The graph which showed the relationship between the surface layer which coat | covers the base material of a developing sleeve, and density unevenness. 1 is a schematic configuration diagram of a printer according to an embodiment. Sectional drawing of an image forming unit. FIG. 2 is an external perspective view of an image forming unit. FIG. 3 is an enlarged configuration diagram illustrating a toner supply device. Sectional drawing of a mono pump. FIG. 6 is a diagram for explaining measurement of thermal characteristics of toner. The figure explaining the process of the developing sleeve surface. 6 is a graph showing the relationship between the presence or absence of external addition of zinc stearate to toner and the surface of the developing sleeve. The graph which showed the relationship between the presence or absence of the external addition of the zinc stearate with respect to a toner, and the tip darkness.

Hereinafter, an embodiment in which the present invention is applied to a printer which is an image forming apparatus will be described.
FIG. 2 is a schematic configuration diagram of the printer according to the present embodiment. FIG. 3 is a cross-sectional view of the image forming unit 1Y. FIG. 4 is an external perspective view of the image forming unit 1Y.

  The printer shown in FIG. 2 includes four image forming units 1Y, 1C, 1M, and 1K for generating yellow, magenta, cyan, and black (hereinafter referred to as Y, C, M, and K) toner images. .

  The image forming units 1Y, 1C, 1M, and 1K use Y toner, C toner, M toner, and K toner of different colors as image forming materials for forming an image, but the other configurations are the same.

  Taking the image forming unit 1Y for generating a Y toner image as an example, the image forming unit 1Y has a photoconductor unit 2Y and a developing device 7Y as shown in FIG. As shown in FIG. 4, the photosensitive unit 2Y and the developing device 7Y are detachably attached to the printer main body integrally as the image forming unit 1Y, and when removed from the printer main body, the developing device 7Y. Can be attached to and detached from the photoreceptor unit 2Y.

  An optical writing unit 20 is disposed below the image forming units 1Y, 1C, 1M, and 1K. The optical writing unit 20 serving as a latent image forming unit irradiates the photoconductors 3Y, 3C, 3M, and 3K of the image forming units 1Y, 1C, 1M, and 1K with laser light L based on the image information. Thereby, electrostatic latent images for Y, C, M, and K are formed on the photoreceptors 3Y, 3C, 3M, and 3K. The optical writing unit 20 applies the laser light L emitted from the light source to the photoreceptors 3Y, 3C, 3M, and 3K via a plurality of optical lenses and mirrors while deflecting the laser light L by a polygon mirror 21 that is rotationally driven by a motor. Irradiation. Instead of such a configuration, it is also possible to employ one that performs optical scanning with an LED array.

  A first paper feed cassette 31 and a second paper feed cassette 32 are arranged below the optical writing unit 20 so as to overlap in the vertical direction. In the first paper feed cassette 31 and the second paper feed cassette 32, a plurality of paper sheets P as recording media are respectively stored in a bundle of paper sheets. Further, the first paper feed roller 31a and the second paper feed roller 32a are in contact with the uppermost paper P, respectively. When the first paper feed roller 31a is driven to rotate counterclockwise in the figure by a driving means (not shown), the uppermost paper P in the first paper feed cassette 31 is in the figure of the first paper feed cassette 31. The paper is discharged toward the paper feed path 33 arranged to extend in the vertical direction on the right side. Further, when the second paper feed roller 32 a is driven to rotate counterclockwise in the figure by a driving means (not shown), the uppermost paper P in the second paper feed cassette 32 is directed toward the paper feed path 33. Discharged.

  A plurality of transport roller pairs 34 are arranged in the paper feed path 33, and the paper P fed into the paper feed path 33 is sandwiched between the rollers of the transport roller pair 34 while being fed. The inside is conveyed from the lower side to the upper side in the figure. A registration roller pair 35 is disposed at the end of the paper feed path 33. The registration roller pair 35 temporarily stops the rotation of both rollers as soon as the paper P sent from the conveyance roller pair 34 is sandwiched between the rollers. Then, the paper P is sent out to a secondary transfer nip described later at an appropriate timing.

  Above each of the image forming units 1Y, 1C, 1M, and 1K, a transfer unit 80 serving as a transfer unit is provided that moves the intermediate transfer belt 81 endlessly counterclockwise while stretching. In addition to the intermediate transfer belt 81, the transfer unit 80 includes a belt cleaning unit 82, a first bracket 83, a second bracket 84, and the like. In addition, four primary transfer rollers 85Y, 85C, 85M, and 85K, a secondary transfer backup roller 86, a drive roller 87, an auxiliary roller 88, a tension roller 89, and the like are also provided.

  The intermediate transfer belt 81 is endlessly moved counterclockwise in the figure by the rotational drive of the driving roller 87 while being stretched around these eight rollers. The four primary transfer rollers 85Y, 85C, 85M, and 85K sandwich the intermediate transfer belt 81 that is moved endlessly in this manner from the photoreceptors 3Y, 3C, 3M, and 3K to form primary transfer nips. . Then, a transfer bias having a polarity (for example, plus) opposite to the charging polarity of the toner is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 81. As the intermediate transfer belt 81 passes through the primary transfer nips for the respective colors Y, C, M, and K in sequence with the endless movement, the intermediate transfer belt 81 has a photosensitive member 3Y, 3C, 3M, 3K on the front surface. The Y toner image, the C toner image, the M toner image, and the K toner image are primarily transferred so as to overlap each other. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 81.

  The secondary transfer backup roller 86 sandwiches the intermediate transfer belt 81 from the secondary transfer roller 50 disposed outside the loop of the intermediate transfer belt 81 to form a secondary transfer nip.

  The sheet P sandwiched between the rollers of the registration roller pair 35 is sent out toward the secondary transfer nip at a timing synchronized with the four-color toner image on the intermediate transfer belt 81. The four-color toner image on the intermediate transfer belt 81 is influenced by the secondary transfer electric field formed between the secondary transfer roller 50 to which the secondary transfer bias is applied and the secondary transfer backup roller 86, and the influence of the nip pressure. Then, the secondary transfer is collectively performed on the paper P in the secondary transfer nip. Then, combined with the white color of the paper P, a full color toner image is obtained.

  The transfer residual toner remaining on the intermediate transfer belt 81 without being transferred to the paper P even after passing through the secondary transfer nip is cleaned by the belt cleaning unit 82. The belt cleaning unit 82 makes the cleaning blade 82 a contact the front surface of the intermediate transfer belt 81, thereby scraping off and removing the transfer residual toner on the intermediate transfer belt 81.

  A fixing unit 60 is disposed above the secondary transfer nip. The fixing unit 60 includes a pressure heating roller 61 and a fixing belt unit 62 that include a heat source such as a halogen lamp.

  The fixing belt unit 62 includes an endless fixing belt 64 as a fixing member, a heating roller 63 including a heat source 63a such as a halogen lamp, a tension roller 65, a driving roller 66, and the like. Then, the fixing belt 64 is moved endlessly in the counterclockwise direction in the drawing while being stretched by the heating roller 63, the tension roller 65, and the driving roller 66. In the process of endless movement, the fixing belt 64 is heated from the back side by the heating roller 63. A pressure heating roller 61 that is driven to rotate in the clockwise direction in the drawing is in contact with the surface of the fixing belt 64 heated in this manner from the front side. Thereby, a fixing nip where the pressure heating roller 61 and the fixing belt 64 abut is formed.

  Outside the loop of the fixing belt 64, a temperature sensor (not shown) is disposed so as to face the front surface of the fixing belt 64 with a predetermined gap, and the fixing belt 64 just before entering the fixing nip. Detect the surface temperature of. The detection result is sent to a fixing power supply circuit (not shown). The fixing power supply circuit performs on / off control of power supply to the heat source 63 a included in the heating roller 63 and the heat source 61 a included in the pressure heating roller 61 based on the detection result by the temperature sensor. Thereby, the surface temperature of the fixing belt 64 is maintained at about 140 [° C.].

  The paper P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 81 and then sent into the fixing unit 60. Then, in the process of being conveyed from the lower side to the upper side in the figure while being sandwiched by the fixing nip in the fixing unit 60, the full-color toner image is fixed by being heated and pressed by the fixing belt 64 and the pressure heating roller 61. I'm damned.

  The paper P subjected to the fixing process in this manner is discharged outside the apparatus after passing between the rollers of the paper discharge roller pair 67. A stack unit 68 is formed on the upper surface of the housing of the printer main body, and the sheets P discharged out of the apparatus by the discharge roller pair 67 are sequentially stacked on the stack unit 68.

  Above the transfer unit 80, toner bottles 19Y, 19C, 19M, and 19K, which are four toner containers that store Y toner, C toner, M toner, and K toner, are disposed. Each color toner in the toner bottles 19Y, 19C, 19M, and 19K is appropriately supplied to the developing devices 7Y, 7C, 7M, and 7K of the image forming units 1Y, 1C, 1M, and 1K. The toner bottles 19Y, 19C, 19M, and 19K can be attached to and detached from the printer main body independently of the image forming units 1Y, 1C, 1M, and 1K.

  The photoconductor unit 2Y includes a drum-shaped photoconductor 3Y as an image carrier, a drum cleaning device 4Y, a static eliminator (not shown), a charging device 5Y, and the like. The charging device 5Y uniformly charges the surface of the photoreceptor 3Y that is driven to rotate in the clockwise direction in the drawing by a driving unit (not shown).

  In FIG. 3, while a charging bias is applied by a power source (not shown), a charging roller 6Y that is driven to rotate counterclockwise in the drawing is brought close to the photosensitive member 3Y to uniformly charge the photosensitive member 3Y. A charging device 5Y is shown. Instead of the charging roller 6Y, a roller that contacts a charging brush may be used. Further, a charger that uniformly charges the photoreceptor 3Y by a charger method, such as a scorotron charger, may be used. The surface of the photoreceptor 3Y uniformly charged by the charging device 5Y is exposed and scanned by a laser beam emitted from an optical writing unit described later, and carries a Y electrostatic latent image.

  The developing device 7Y as developing means has a first agent accommodating portion 9Y in which a first conveying screw 8Y is disposed. Further, it also has a second agent containing portion 14Y in which a toner concentration sensor 10Y composed of a magnetic permeability sensor, a second conveying screw 11Y, a developing roller 12Y, a doctor blade 13Y, and the like are arranged. In these two agent accommodating portions, a Y developer (not shown) having a magnetic carrier and negatively chargeable Y toner is included. The first conveying screw 8Y is driven to rotate by a driving means (not shown), and conveys the Y developer in the first agent accommodating portion 9Y from the front side to the back side in the drawing. Then, the Y developer is caused to enter the second agent accommodating portion 14Y through a communication port (not shown) provided in the partition wall between the first agent accommodating portion 9Y and the second agent accommodating portion 14Y.

  The second conveying screw 11Y in the second agent accommodating portion 14Y is driven to rotate, and conveys the Y developer from the back side to the near side in the drawing. The toner density of the Y developer being conveyed is detected by the toner density sensor 10Y fixed to the bottom of the second agent container 14Y. Above the second conveying screw 11Y, a developing roller 12Y is disposed in parallel with the second conveying screw 11Y.

  The developing roller 12Y includes a magnet roller 16Y serving as a magnetic field generating unit in a developing sleeve 15Y formed of a pipe using a nonmagnetic metal such as aluminum as a base material, which is driven to rotate counterclockwise in the drawing. Yes. In addition, as a base material of the developing sleeve 15, brass or the like may be used instead of aluminum.

  A part of the Y developer conveyed by the second conveying screw 11Y is pumped up to the surface of the developing sleeve by the magnetic force generated by the magnet roller 16Y. The layer thickness of the Y developer pumped up on the surface of the developing sleeve is regulated by the doctor blade 13Y disposed so as to maintain a predetermined gap with the developing sleeve 15Y as the developing member. After the layer thickness is regulated in this way, the Y developer is transported to the development area facing the photoreceptor 3Y, and Y toner is attached to the Y electrostatic latent image on the photoreceptor 3Y. This adhesion forms a Y toner image on the photoreceptor 3Y.

  The Y developer that has consumed Y toner by development is returned to the second conveying screw 11Y as the developing sleeve 15Y rotates. Then, when the Y developer is transported to the front end in the drawing by the second transport screw 11Y, the Y developer returns from the second agent housing portion 14Y to the first agent housing portion 9Y through a communication port (not shown).

  The result of detecting the magnetic permeability of the Y developer by the toner concentration sensor 10Y is sent as a voltage signal to a control unit (not shown). Since the magnetic permeability of the Y developer shows a correlation with the Y toner density of the Y developer, the toner density sensor 10Y outputs a voltage having a value corresponding to the Y toner density.

  The control unit includes a RAM, in which Y Vtref, which is a target value of the output voltage from the toner density sensor 10Y, and output voltage from each toner density sensor mounted on the other developing device 7 are stored. Data of C Vtref, M Vtref, and K Vtref, which are target values, are stored.

  For the developing device 7Y, the value of the output voltage from the toner density sensor 10Y is compared with the Y Vtref, and the Y toner replenishing device described later is driven for a time corresponding to the comparison result. With this driving, an appropriate amount of Y toner is supplied from the first agent storage portion 9Y to the Y developer whose Y toner has been consumed by developing and whose Y toner density has been reduced. For this reason, the Y toner density in the second agent container 14Y is maintained within a predetermined range. The same toner supply control is performed for the developers in the image forming units 1C, 1M, and 1K for other colors.

  The Y toner image formed on the photoreceptor 3Y is intermediately transferred to the intermediate transfer belt 81. Further, the toner remaining on the surface of the photoconductor after the intermediate transfer process is removed by the drum cleaning device 4Y, and the surface of the photoconductor subjected to the cleaning process in this way is discharged by a static eliminator (not shown). By this charge removal, the surface of the photoreceptor 3Y is initialized and prepared for the next image formation.

  In FIG. 2, in the image forming units 1C, 1M, and 1K for other colors, C toner images, M toner images, and K toner images are similarly formed on the photoreceptors 3C, 3M, and 3K, and the intermediate transfer belt 81 is formed. Intermediate transfer is performed on the top.

  A temperature sensor (not shown) used in the present embodiment is installed in the developing device 7Y or in the vicinity of the developing device 7Y in the image forming apparatus body, that is, at a position where the detected temperature has a high correlation with the developing device internal temperature. The image forming units 1C, 1M, and 1K for other colors have the same configuration.

  The drum cleaning device 4Y includes a cleaning blade 41Y as a cleaning member. The cleaning blade 41Y is supported in a counter manner with respect to the photosensitive body surface moving direction. The drum cleaning device 4Y also includes a waste toner collection coil (not shown) for conveying the transfer residual toner scraped and collected by the cleaning blade 41Y to a waste toner bottle (not shown).

  In the present embodiment, a lubricant application device is disposed downstream of the cleaning blade 41Y in the direction of movement of the photoreceptor surface and upstream of the charging device 5Y in the direction of movement of the photoreceptor surface. The lubricant application device includes a brush roller 42Y as a lubricant supply member, a solid lubricant (not shown) made of zinc stearate provided in contact with the brush roller 42Y, and a solid lubricant pressed against the brush roller 42Y. And a pressurizing spring.

  The brush roller 42Y is also in contact with the surface of the photoreceptor 3Y and is driven to rotate clockwise in the drawing. The brush roller 42Y is a roller formed by winding a brush around a metal shaft. The brush portion scrapes off the lubricant from the solid lubricant and applies the scraped powder lubricant to the surface of the photoreceptor. The lubricant used in the present embodiment is zinc stearate, but is not limited to this.

  Further, as shown in FIG. 3, the lubricant application device includes a lubricant leveling blade 43Y that comes into contact with the surface of the photoconductor 3Y on the downstream side in the moving direction of the photoconductor surface with respect to the contact portion of the brush roller 42Y. The lubricant leveling blade 43Y is made of polyurethane rubber, and its support system is a counter system.

  FIG. 5 is an enlarged configuration diagram illustrating the toner supply device 130. The toner bottle 19 serving as a toner container includes a bottle portion 191 that contains toner, and a cap portion 192 that engages with the head portion of the bottle portion 191 and rotatably holds the bottle portion 191. When the toner bottle 19 is attached to the printer body, the nozzle 142 is inserted into the hole 192b of the cap portion 192 in conjunction with the attachment operation. At this time, the plug member 193 as an opening / closing member of the toner bottle 19 opens the toner discharge port 192a (powder discharge port) while being sandwiched between the nozzle 142 and the claw member 145. As a result, the toner receiving port (powder receiving port) provided in the nozzle 142 and the toner discharge port 192a communicate with each other.

  The bottle portion 191 of the toner bottle 19 is formed in a substantially cylindrical shape, and a spiral protrusion 191a is provided on the inner peripheral surface (a spiral groove when viewed from the outer peripheral surface side). . When the bottle unit 191 is rotationally driven in the direction of the arrow in the drawing by a toner container driving unit (not shown) provided in the apparatus main body, the helical projection 191a removes the toner stored in the bottle unit 191 from the cap unit 192. Send out towards the space inside. Thereby, the toner accommodated in the bottle portion 191 of the toner bottle 19 is conveyed into the nozzle 142 through the toner discharge port 192a.

  On the other hand, one end of a tube 139 as a toner supply path is connected to the other end of the nozzle 142. The tube 139 is made of a flexible material excellent in toner resistance, and the other end thereof is connected to a MONO pump 131 which is a screw pump serving as a toner supply unit of the toner replenishing device 130. As the material of the tube 139, rubber materials such as polyurethane, nitrile, EPDM, and silicone, and resin materials such as polyethylene and nylon can be used. By using such a flexible tube 139, the degree of freedom of the layout of the toner replenishment path is increased, and the printer can be miniaturized.

  The Mono pump 131 is a suction type uniaxial eccentric screw pump, and includes a rotor 135, a stator 132, a suction port 133, a drive shaft 134, a motor 136, and the like. The rotor 135, the stator 132, the drive shaft 134, and the like are housed in a case (not shown). The stator 132 is a female threaded member made of an elastic material such as rubber, and a double pitch spiral groove is formed in the stator 132. The rotor 135 is a male screw-like member formed by twisting a spiral made of a rigid material such as metal, and is inserted into the stator 132 so as to be rotatable. One end of the rotor 135 is connected to the motor 136 via the drive shaft 134.

  The MONO pump 131 rotates the rotor 135 in the stator 132 in a predetermined direction by the motor 136 to generate a suction force at the suction port 133 (feeds out air in the tube 139 and generates negative pressure in the tube 139). ). As a result, the toner in the toner bottle 19 is sucked into the suction port 133 through the tube 139 together with the air. The toner sucked up to the suction port 133 is sent into the gap between the stator 132 and the rotor 135, sent to the other end side along the rotation of the rotor 135, and then inside the developing device 7 via the toner transport pipe 138. Will be replenished. A hopper that temporarily stores toner to be replenished to the developing device 7 may be installed between the mono pump 131 and the developing device 7.

A cross-sectional view of the MONO pump 131 used as a replenishing device in this embodiment is shown in FIG.
The MONO pump 131 includes a stator 132 having a through hole 106, a rotor 135 disposed in the through hole 106 and driven to rotate, and a drive shaft 134 that drives the rotor 135 to rotate. It is contained in. The through hole 106 has two spiral grooves, whereas the rotor 135 is a single spiral rod. Therefore, when the rotor 135 is disposed in the through hole 106, a gap G is formed.

  When the rotor 135 is rotationally driven by the drive shaft 134, the gap G moves from the right to the left in the drawing. Therefore, a suction pressure is generated at the inlet opening 120 of the through hole 106, that is, the toner suction side of the MONO pump 131, and the toner at the position of T1 is fed into the gap G (T2). The toner is conveyed to the left as it is, discharged from the outlet opening 121 of the through hole 106 to the position of T3, and replenished into the developing device.

FIG. 7 is a diagram for explaining the thermal characteristic measurement of the toner.
In order to reduce power consumption, a toner having a low temperature fixing is used. In particular, the crystalline polyester resin in the toner exhibits crystallinity, and thus exhibits a heat melting characteristic that exhibits a sudden viscosity drop near the fixing start temperature.

  In other words, the toner has good heat-resistant storage stability due to crystallinity until just before the melting start temperature, and suddenly drops in viscosity (sharp melt) at the melting start temperature and fixes, so it has both good heat storage stability and low-temperature fixability. Can be designed.

  However, as a result of an experiment in which a low-temperature fixing toner having a T1 / 2 outflow temperature of 110 [° C.] is added to the MPC 5001, when the amount of zinc stearate added is 0.05 [wt%] or less, the toner is separated from the toner bottle. In some cases, the toner was fixed inside the toner supply pump between the developing devices, and the pump was damaged. It has been confirmed that if it is 0.05% by weight or more, there is an effect of preventing toner sticking.

  Therefore, by adding 0.05 wt% or more of zinc stearate, a low temperature fixing toner having a T1 / 2 outflow temperature of 110 [° C.] or less can be used, and the power consumption can be reduced by lowering the fixing temperature. Can be planned.

Toner thermal characteristics (flow tester characteristics)
An example of a flow tester for measuring the thermal characteristics of toner is an elevated flow tester CFT500 manufactured by Shimadzu Corporation. The flow curve of this flow tester becomes the data shown in FIGS. 7A and 7B, from which each temperature can be read. In the figure, Ts is the softening temperature, Tfb is the outflow start temperature, and the melting temperature in the 1/2 method is the T1 / 2 temperature.

<Measurement conditions>
Load: 10 [kg / cm ² ]
Temperature increase rate: 3.0 [° C./min]
Die diameter: 0.50 [mm]
Die length: 10.0 [mm]

FIG. 8 is an enlarged view of the vicinity of the surface of the developing sleeve 15.
The surface of the developing sleeve 15 is uneven, improving the developer transportability on the developing sleeve 15. In addition, as a method of making the developing sleeve surface uneven, it can be performed, for example, by sandblasting or etching. Further, a plurality of V-shaped grooves may be provided on the surface of the developing sleeve 15 in the axial direction of the developing sleeve.

  In the present embodiment, the high-speed sandblasting process is performed in which the blasting standard for sandblasting performed on the surface of the developing sleeve is # 200 or more and the injection pressure is 6 [kgf] or more. As a result, a rough surface of Rz5 [μm] to 10 [μm] is formed on the developing sleeve 15, and the developer can be efficiently conveyed on the surface of the developing sleeve.

  A film 15b of ta-C (tetrahedral amorphous carbon), which is a type of DLC (diamond-like carbon), is formed on the surface of the base material 15a made of aluminum of the developing sleeve 15 by a FCVA (Filtered Cathodic Vacuum Arc) method. Has been.

  Here, carbon in which carbon bonds are combined with graphite bonds (sp2 bonds) and diamond bonds (sp3 bonds) is called DLC (diamond-like carbon). The ratio of the sp3 structure by carbon atoms (the ratio of carbon atoms bonded to sp3) is obtained by separating the peaks of the energy loss function from the electron beam energy loss spectrum connected to a transmission electron microscope (TEM), and the area of each peak. Calculated from the ratio. A DLC having a low hydrogen content and a high sp3 bond ratio is referred to as ta-C. Since a hard thin film with a smaller hydrogen content and more sp3 bonds can be obtained and wear resistance is excellent, it is possible to provide a developing device 7 in which developer transportability does not vary even when used for a long period of time.

  The ta-C film can be formed by a method such as CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). The FCVA (Filter Cathodic Vacuum Arc) method described above is particularly suitable because it can easily form a DLC film with less hydrogen and a high sp3 bond ratio. The ratio of sp3 bonds is desirably 40% or more and 85% or less, and desirably 70% or more. The ta? C layer preferably has a hydrogen atom content of 10 [atm%] or less. The content of hydrogen atoms is calculated by measuring from the surface of the ta? C layer to a depth of 1 [nm] by the hydrogen forward scattering method (HFS).

  In FCVA vapor deposition, first, arc discharge is performed on a target in a substantially vacuum chamber to generate plasma. The generated plasma is guided to the developing sleeve 15 to be deposited by electromagnetic induction, and in the process, macro particles and neutral atoms / molecules unnecessary for deposition are formed in, for example, an opening provided in a bent portion of the guiding path. It is removed by being guided out of the path from the part. High-purity ions reaching the developing sleeve 15 aggregate there to form a film. As a result, the developing sleeve 15 is coated with high-purity molecules.

  When carbon (graphite) having high purity is used for the target in the FCVA vapor deposition, a thin-film ta? C film can be formed on the base material 15a. Further, by applying a negative bias to the developing sleeve during film formation, the energy of the carbon ion particles can be changed, and the sp3 bond ratio can be adjusted. The coating 15b formed by FCVA vapor deposition is particularly suitable because it is thin, hard and homogeneous.

  Here, as a result of intensive studies by the inventors of the present application, when using a toner to which zinc stearate is externally added, density unevenness called “high density of the tip” is worsened, where the leading edge of the solid image becomes darker by one round of the developing sleeve. It turns out that there is a case.

  In particular, it has been found that the combination of a small particle size polymerized toner (5.2 [μm]: used in Imagio MPC5001 and the like) and zinc stearate, which have been developed for improving image quality in recent years, tends to deteriorate the darkness of the tip. As described above, when zinc stearate is added to the toner having a small particle diameter, abnormal images such as “cleaning failure” and “filming” can be suppressed, and density unevenness called “deep tip” is likely to occur. There was a problem.

  Using the developing device of Imagio MPC5001, the surface of the developing sleeve is agitated when the toner concentration is 9 [%], and when zinc stearate is externally added to the toner in 0.2 [wt%], and zinc stearate is added to the toner. Measured with and without external addition. As a result, as shown in FIG. 9, when the zinc stearate was externally added to the toner, the stain on the developing sleeve surface was worse than when the zinc stearate was not externally added to the toner.

  In addition, using a developer in which zinc stearate is externally added to the toner to 0.2 [wt%] and a developer in which zinc stearate is not externally added to the toner, an image area ratio of 5% is 3000 sheets. Density unevenness called “dark tip” after output was compared in a 27 [° C.] 80 [%] environment. As a result, as shown in FIG. 10, the density unevenness called “deep tip” was worse when the zinc stearate was externally added to the toner than when the zinc stearate was not externally added to the toner.

  On the other hand, by forming a ta-C (tetrahedral amorphous carbon) film 15b on the surface of the base material 15a of the developing sleeve 15 as in this embodiment, the space between the developing sleeve 15 and the toner is formed. Adhesion can be reduced. As a result, even when a toner to which zinc stearate is added is used, toner adhesion to the developing sleeve 15 can be suppressed, and toner adhesion to the developing sleeve 15 in the non-image portion of the developing sleeve 15 can be suppressed. . For this reason, the toner adheres to the developing sleeve 15 without any change in the image portion and the non-image portion, and the occurrence of density unevenness called “deep tip” can be suppressed.

In addition to ta-C, the same effect can be obtained with a DLC (Diamond Like Carbon) film by a CVA method or the like, a MoS ₂ (molybdenum sulfide) film, a tin (Sn) plating, or an Al ₂ O ₃ (aluminum oxide) film. It is done. However, a ta-C film by the FCVA (Filtered Cathodic Vacuum Arc) method is suitable because a hard and thin coating can be easily produced. As a result, it is possible to obtain a high-quality image without generating a dark tip while preventing poor cleaning and filming.

That is, as the developing sleeve 15, a DLC film, a ta-C film, a MoS ₂ (molybdenum sulfide) film, The one coated with tin (Sn) plating or Al ₂ O ₃ (aluminum oxide) coating is used.

  Thereby, the adhesive force generated between the surface of the developing sleeve and the toner can be reduced as compared with the case where the substrate is not covered with the surface layer. Therefore, even when a toner to which a fatty acid metal salt such as zinc stearate is added is used, toner adhesion to the developing sleeve 15 can be suppressed, and toner adheres to the developing sleeve 15 in the non-image portion of the developing sleeve 15. Is suppressed. For this reason, the toner does not adhere to the developing sleeve 15 without changing in the image portion and the non-image portion, and density unevenness occurs between the portion where the toner is attached and the portion where the toner is not attached on the surface of the developing sleeve. The occurrence of density unevenness called "" can be suppressed.

  Also, density unevenness called “deep tip” is remarkable when the toner density is high in a small-diameter toner. In the toner having a volume average particle diameter of 6.8 [μm], even if the toner concentration is 11 [%], the tip is hardly dark. On the other hand, in the toner having a volume average particle size of 5.2 [μm] and 5.8 [μm], the image density ID is 0.05 to 0.1 worse at “toner end” at a toner concentration of 9 [%]. However, by forming the ta-C film on the surface of the developing sleeve, it was possible to make the fluctuation of the image density ID 0.02 or less.

  The volume average particle diameter of the toner was measured with a particle size measuring device “Coulter Counter TAII” manufactured by Coulter Electronics Co., Ltd., with an aperture diameter of 100 [μm]. The volume average particle size and the number average particle size were determined by the particle size measuring instrument.

  Further, the toner concentration in the developer is defined by Equation 1.

  As an external additive externally added to the toner for lubrication, various fatty acid metal salts can be used. From the viewpoint of obtaining good cleaning properties, environmental stability and chargeability, zinc stearate is used. Particularly preferred. Other fatty acid metal salts can be appropriately selected according to the purpose. For example, zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, zinc oleate, zinc palmitate, magnesium palmitate, myristic Examples thereof include zinc acid, zinc laurate, and zinc behenate.

  In this embodiment, the amount of zinc stearate added externally to the toner is 0.30 [wt%] or less. It has been confirmed that when the amount of zinc stearate added is increased, background stains may occur. On the other hand, if the amount of zinc stearate added is 0.30 [% by weight] or less, it can be used without any problem with almost no background stains.

  Next, the toner used in this embodiment will be described.

(Effect of crystalline polyester)
Since the crystalline polyester resin in the toner has crystallinity, it exhibits a heat-melting characteristic that shows a rapid viscosity decrease near the fixing start temperature. In other words, the toner has good heat-resistant storage stability due to crystallinity until just before the melting start temperature, and suddenly drops in viscosity (sharp melt) at the melting start temperature and fixes, so it has both good heat storage stability and low-temperature fixability. Can be designed. It was also found that good results were obtained with respect to the release width (difference between the fixing lower limit temperature and the hot offset occurrence temperature).

(Circularity and circularity distribution)
It is important that the toner in the present exemplary embodiment has a specific shape and distribution of the shape. With an irregularly shaped toner having an average circularity of less than 0.95 and far from a spherical shape, satisfactory transferability and High-quality images without dust cannot be obtained.

  As a method for measuring the shape, an optical detection band method is suitable in which a suspension containing particles is passed through an imaging unit detection band on a flat plate, and a particle image is optically detected and analyzed by a CCD camera. is there. A toner with an average circularity of 0.99 to 0.95, which is a value obtained by dividing the perimeter of an equivalent circle having the same projected area obtained by this method by the perimeter of the actual particle, has a high density with a reproducibility of an appropriate density. It was found to be effective in forming a clear image. More preferably, particles having an average circularity of 0.99 to 0.96 and a circularity of less than 0.96 are 10% or less.

  When the average circularity is 0.991 or more, in a system that employs blade cleaning or the like, a cleaning failure occurs on the photosensitive member 3 and the transfer belt, causing stain on the image. For example, development / transfer with a low image area ratio results in a small amount of residual toner and poor cleaning does not pose a problem, but images with a high image area ratio such as photographic images, and untransferred images due to poor paper feed, etc. The formed toner may be generated as untransferred toner on the photosensitive member 3, and if it is accumulated, the background stain of the image occurs. Further, the charging roller or the like that contacts and charges the photoreceptor 3 is contaminated, and the original charging ability cannot be exhibited.

  This value can be measured as an average circularity by a flow type particle image analyzer FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd.). As a specific measuring method, 0.1 [ml] surfactant, preferably alkylbenzene sulfonate, is used as a dispersant in 100 [ml] to 150 [ml] of water from which impure solids have been removed in advance. ] To 0.5 [ml], and about 0.1 [g] to 0.5 [g] of a measurement sample is further added. The suspension in which the sample is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the dispersion concentration is set to 3000 [pieces / μl] to 10000 [pieces / μl]. Is obtained by measuring.

(Dv / Dn (ratio of volume average particle diameter / number average particle diameter))
The volume average particle diameter (Dv) of the toner is 4 [μm] to 8 [μm], and the ratio (Dv / Dn) to the number average particle diameter (Dn) is 1.25 or less, preferably 1.05 to 1. .20 dry toner is excellent in all of heat-resistant storage stability, low-temperature fixability, and hot offset resistance, especially when used in a full-color copying machine, and in a two-component developer. Even if the toner balance is performed over a long period of time, fluctuations in the toner particle size in the developer are reduced, and good and stable developability can be obtained even with long-term stirring in the developing device. In addition, even when used as a one-component developer, even if the balance of toner is performed, fluctuations in the particle size of the toner are reduced, and toner filming on the developing roller and toner thinning are performed. The toner was not fused to a member such as a blade, and good and stable developability and images were obtained even when the developing device was used (stirred) for a long time.

  In general, it is said that the smaller the particle size of the toner, the more advantageous it is to obtain a high-resolution and high-quality image, but it is disadvantageous for transferability and cleaning properties. is there. Further, when the volume average particle diameter is smaller than the range of the present embodiment, in the case of the two-component developer, the toner is fused to the surface of the carrier during a long period of stirring in the developing device, and the charging ability of the carrier is reduced. When used as a developer, toner filming on the developing roller and toner fusion to a member such as a blade for thinning the toner are likely to occur.

  Further, these phenomena are the same for the toner having a fine powder content higher than the range of the present embodiment.

  Conversely, when the particle size of the toner is larger than the range of the present embodiment, it becomes difficult to obtain a high-resolution and high-quality image, and the toner in the developer is balanced. In many cases, the variation in the particle size of the particles increases. It was also clarified that the volume average particle diameter / number average particle diameter was larger than 1.25.

  Further, when the volume average particle diameter / number average particle diameter is smaller than 1.05, there are preferable aspects from the viewpoint of stabilizing the behavior of the toner and equalizing the charge amount, but the toner can be sufficiently charged. It became clear that there were cases where it was not possible or the cleaning performance was deteriorated.

(Modified polyester resin)
Examples of the modified polyester resin (i) include polyester prepolymers modified with isocyanate or epoxy. This undergoes an extension reaction with a compound having an active hydrogen group (such as amines), and has an effect of improving the release width (difference between the minimum fixing temperature and the hot offset generation temperature). As a method for synthesizing the modified polyester resin (i), it can be easily synthesized by reacting a conventionally known isocyanate agent or epoxidizing agent with a base polyester resin.

  Isocyanating agents include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6 diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); aromatic diisocyanates ( Tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; And combinations of two or more of these. Moreover, as an epoxidizing agent, epichlorohydrin etc. can be mentioned as the representative example.

  The ratio of the isocyanate agent is usually 5/1 to 1/1, preferably 4/1 to 1 as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the base polyester. 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. If the molar ratio of [NCO] is less than 1, the urea content in the modified polyester will be low, and the hot offset resistance will deteriorate. The content of the isocyanate agent in the modified polyester resin is usually 0.5 [wt%] to 40 [wt%], preferably 1 [wt%] to 30 [wt%], more preferably 2 [wt%]. ] To 20 [% by weight]. If it is less than 0.5 [% by weight], the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 [% by weight], the low-temperature fixability deteriorates.

  In addition, the number of isocyanate groups contained per molecule in the modified polyester resin is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. is there. When the number is less than 1 per molecule, the molecular weight of the urea-modified polyester after the elongation reaction becomes low, and the hot offset resistance deteriorates.

  Examples of amines include diamine compounds, trivalent or higher polyamine compounds, amino alcohol compounds, amino mercaptan compounds, amino acid compounds, and compounds in which these amino groups are blocked.

  Examples of diamine compounds include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′dimethyldicyclohexylmethane, diaminecyclohexane, isophoronediamine). Etc.); and aliphatic diamines (ethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.) and the like.

  Examples of the trivalent or higher polyamine compound include diethylenetriamine and triethylenetetramine. Examples of amino alcohol compounds include ethanolamine and hydroxyethylaniline. Examples of the amino mercaptan compound include aminoethyl mercaptan and aminopropyl mercaptan. Examples of amino acid compounds include aminopropionic acid and aminocaproic acid. Examples of the compounds in which these amino groups are blocked include ketimine compounds and oxazoline compounds obtained from the amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines, preferred are a diamine compound and a mixture of a diamine compound and a small amount of a polyamine compound. Moreover, amines can be used as a crosslinking agent and an extender.

  Furthermore, if necessary, the molecular weight of the urea-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

  The ratio of amines is usually 1/2 to 2/1 as equivalent ratio [NCO] / [NHx] of isocyanate group [NCO] in modified polyester resin and amino group [NHx] in amines, preferably The ratio is 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester after the extension reaction is lowered, and the hot offset resistance is deteriorated. In the present embodiment, the urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.

  The urea-modified polyester after the extension reaction in the present embodiment is produced by a one-shot method or a prepolymer method. The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester is not particularly limited when using an unmodified polyester described later, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When used alone, the number average molecular weight is usually 20000 or less, preferably 1000 to 10000, and more preferably 2000 to 8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.

(Unmodified polyester)
In the present embodiment, not only the urea-modified polyester but also a polyester resin (ii) that is not modified with the urea-modified polyester can be contained as a toner binder component. By using (ii) in combination, the low-temperature fixability and the gloss when used in a full-color device are improved, which is preferable to the single use. The above (i) and (ii) are preferably at least partially compatible in terms of low temperature fixability and hot offset resistance. Therefore, the polyester component (i) and (ii) preferably have similar compositions.

  The peak molecular weight of (ii) is usually 1000-30000, preferably 1500-10000, more preferably 2000-8000. If it is less than 1000, heat-resistant storage stability will deteriorate, and if it exceeds 10,000, low-temperature fixability will deteriorate. The weight average molecular weight of the unmodified polyester resin (ii) is preferably 2000 to 90000, and the glass transition point (Tg) is preferably 40 to 80 ° C.

  The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80. If it is less than 5, it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The acid value of (ii) is usually 1-30, preferably 5-20. By having an acid value, it tends to be negatively charged. Further, those having an acid value and a hydroxyl value exceeding these ranges are easily affected by the environment under high temperature and high humidity and low temperature and low humidity, and are liable to cause image deterioration.

(Crystalline polyester)
The crystalline polyester (iii) is a polyester having at least a melting point. Examples of the crystalline polyester (iii) include diol compounds having 2 to 6 carbon atoms, particularly 1,4-butanediol, 1,6-hexanediol and alcohol components containing these derivatives, maleic acid, and fumaric acid. A crystalline polyester resin having a repeating unit represented by Chemical Formula 1 synthesized with an acid component containing succinic acid and derivatives thereof is preferable.

(In the formula, R1 and R2 are hydrocarbon groups, and the number of carbon atoms is 1 to 20. Also, n is a natural number.)

  In addition, as a method for controlling the crystallinity and softening point of the crystalline polyester resin, a trivalent or higher polyhydric alcohol such as glycerin as an alcohol component and a trivalent or higher polyvalent such as trimellitic anhydride as an acid component can be used during polyester synthesis. Examples thereof include a method of designing and using a non-linear polyester that has been subjected to condensation polymerization by adding a polyvalent carboxylic acid.

  The molecular structure of the crystalline polyester can be confirmed by solid NMR. As for the molecular weight, as a result of intensive studies from the viewpoint that the above-mentioned molecular weight distribution is sharp and the low molecular weight is excellent in low-temperature fixability, the molecular weight distribution by GPC of the soluble part of o-dichlorobenzene is expressed by log (M ), The peak position of the molecular weight distribution diagram in which the vertical axis is expressed in weight% is in the range of 3.5 to 4.0, the half width of the peak is 1.5 or less, and the weight average molecular weight (Mw) is 1000 to 1000. It was found that 6500, the number average molecular weight (Mn) is 500 to 2000, and Mw / Mn is preferably 2 to 5. It has been found that the melting temperature and the F1 / 2 temperature are desirably low so long as the heat resistant storage stability does not deteriorate, and are preferably in the range of 50 [° C.] to 130 [° C.].

  When the melting temperature and F1 / 2 temperature are 50 [° C.] or lower, the heat-resistant storage stability is deteriorated, and blocking tends to occur at the temperature inside the developing device, and when it is 130 [° C.] or higher, the minimum fixing temperature is high. Therefore, low-temperature fixability cannot be obtained.

  The dispersed particle diameter of the crystalline polyester resin in the toner is preferably 0.2 [μm] to 3.0 [μm] in terms of the major axis diameter.

  The acid value of the crystalline polyester is 8 [mgKOH / g] or more, more preferably 20 [mgKOH / g] in order to achieve the desired low-temperature fixability from the viewpoint of the affinity between paper and resin. g] or more is preferable. On the other hand, in order to improve the hot offset property, it is preferably 45 [mgKOH / g] or less. Furthermore, the hydroxyl value of the crystalline polymer is 0 [mg KOH / g] to 50 [mg KOH / g], more preferably 5 in order to achieve a predetermined low-temperature fixability and good charging characteristics. [MgKOH / g] to 50 [mgKOH / g] are preferred.

  In the toner according to the exemplary embodiment, the weight ratio of (i), (ii), and (iii) in the toner is usually (i) / (ii) + (iii) in order to develop low-temperature fixability. 5/95 to 25/75, preferably 10/90 to 25/75, more preferably 12/88 to 25/75, particularly preferably 12/88 to 22/78, and (ii) and (iii) ) Is 99/1 to 50/50, preferably 95/5 to 60/40, more preferably 90/10 to 65/35. Outside the above range, hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.

  In this embodiment, the glass transition point (Tg) of the toner binder is usually 40 [° C.] to 70 [° C.], preferably 40 [° C.] to 65 [° C.]. If it is less than 40 [° C.], the heat-resistant storage stability of the toner is deteriorated, and if it exceeds 70 [° C.], the low-temperature fixability is insufficient.

  Due to the coexistence of the urea-modified polyester resin, the image forming toner of the present embodiment tends to have good heat-resistant storage stability even when the glass transition point is low, as compared with known polyester-based toners.

As the storage elastic modulus of the toner binder, the temperature (TG ′) at which the measurement frequency is 20 [Hz] is 10000 [dyne / cm ² ] is usually 100 [° C.] or more, preferably 110 [° C.] to 200 [° C.]. It is. If it is less than 100 [° C.], the hot offset resistance deteriorates.

  As the viscosity of the toner binder, the temperature (Tη) at which a poise of 1000 at a measurement frequency of 20 [Hz] is usually 180 [° C.] or less, preferably 90 [° C.] to 160 [° C.]. If it exceeds 180 [° C.], the low-temperature fixability deteriorates. That is, TG ′ is preferably higher than Tη from the viewpoint of achieving both low temperature fixability and hot offset resistance. In other words, the difference between TG ′ and Tη (TG′−Tη) is preferably 0 ° C. or more. More preferably, it is 10 [° C.] or more, and particularly preferably 20 [° C.] or more. The upper limit of the difference is not particularly limited. Further, from the viewpoint of achieving both heat-resistant storage stability and low-temperature fixability, the difference between Tη and Tg is preferably 0 [° C.] to 100 [° C.]. More preferably, it is 10 [° C] to 90 [° C], and particularly preferably 20 [° C] to 80 [° C].

  In the molecular weight distribution of the THF-soluble component of the polyester resin contained in the toner, the molecular weight peak is 1000 to 30000, the molecular weight of 30000 or more is 1 [wt%] to 80 [wt%], and several It is preferable that an average molecular weight is 2000-15000. Further, in the molecular weight distribution of the THF soluble part of the polyester resin contained in the toner, the component having a molecular weight of 1000 or less is preferably 0.1 [wt%] to 5.0 [wt%]. Further, the THF-insoluble content of the polyester resin contained in the toner is preferably 1 [wt%] to 15 [wt%].

(Coloring agent)
As the colorant of this embodiment, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow oxidation Iron, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Faisa Red, Parachlor Rutonitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carnmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazo Red, polyazo red, chrome vermillion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue rake, peacock blue rake, Victoria blue rake, metal free phthalocyanine blue, phthalocyanine blue, fast sky blue, indance Ren Blue (RS, BC), Indigo, Ultramarine Blue, Bitumen, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chrome Oxide, Pyridian, Emerald Green , Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green , Phthalocyanine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 [wt%] to 15 [wt%], preferably 3 [wt%] to 10 [wt%] based on the toner.

  The colorant used in this embodiment can also be used as a master batch combined with a resin.

  As the binder resin to be kneaded together with the production of the masterbatch or the masterbatch, in addition to the modified and unmodified polyester resins mentioned above, styrene such as polystyrene, poly p-chlorostyrene, polyvinyltoluene, and polymers of substituted products thereof; Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α- Chloromethyl methacrylate copolymer, Tylene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-malein Styrene copolymers such as acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, poly Acrylic resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. The

  This master batch can be obtained by mixing and kneading a resin for a master batch and a colorant under a high shear force to obtain a master batch. At this time, an organic solvent can be used to enhance the interaction between the colorant and the resin. In addition, a so-called flushing method, which is a wet cake of a colorant, is a method of mixing and kneading an aqueous paste containing water of a colorant together with a resin and an organic solvent, transferring the colorant to the resin side, and removing moisture and organic solvent components. Can be used as it is, so that it is not necessary to dry and is preferably used. For mixing and kneading, a high shear dispersion device such as a three-roll mill is preferably used.

(Release agent)
Further, a wax may be contained together with the toner binder and the colorant. Known waxes can be used as the wax of the present embodiment, for example, polyolefin wax (polyethylene wax, polypropylene wax, etc.); long chain hydrocarbon (paraffin wax, sazol wax, etc.); carbonyl group-containing wax, etc. Can be mentioned.

  Of these, carbonyl group-containing waxes are preferred. Examples of the carbonyl group-containing wax include polyalkanoic acid esters (carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18. -Octadecanediol distearate, etc.); polyalkanol esters (tristearyl trimellitic acid, distearyl maleate, etc.); polyalkanoic acid amides (ethylene diamine dibehenyl amide, etc.); polyalkylamides (trimellitic acid tristearyl amide, etc.) And dialkyl ketones (such as distearyl ketone).

  Among these carbonyl group-containing waxes, polyalkanoic acid esters are preferred.

  The melting point of the wax of the present embodiment is usually 40 [° C.] to 160 [° C.], preferably 50 [° C.] to 120 [° C.], more preferably 60 [° C.] to 90 [° C.]. A wax having a melting point of less than 40 [° C.] has an adverse effect on heat-resistant storage stability, and a wax having a melting point of more than 160 [° C.] tends to cause a cold offset when fixing at a low temperature.

  Further, the melt viscosity of the wax is preferably 5 [cps] to 1000 [cps], more preferably 10 [cps] to 100 [cps] as a measured value at a temperature 20 [° C.] higher than the melting point. Waxes exceeding 1000 [cps] are poor in improving hot offset resistance and low-temperature fixability. The content of the wax in the toner is usually 0 [wt%] to 40 [wt%], preferably 3 [wt%] to 30 [wt%].

(Charge control agent)
The toner of the exemplary embodiment may contain a charge control agent as necessary. All known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified). Quaternary ammonium salts), alkylamides, phosphorus simple substances or compounds, tungsten simple substances or compounds, fluorine-based activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives.

  Specifically, Nitronine-based dye Bontron 03, quaternary ammonium salt Bontron P-51, metal-containing azo dye Bontron S-34, oxynaphthoic acid metal complex E-82, salicylic acid metal complex E- 84, E-89 of a phenol-based condensate (manufactured by Orient Chemical Industry Co., Ltd.), TP-302 of a quaternary ammonium salt molybdenum complex, TP-415 (manufactured by Hodogaya Chemical Industry Co., Ltd.), quaternary ammonium Copy charge PSY VP2038 of salt, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit), copper phthalocyanine, perylene, quinaclide And azo pigments, and other high molecular compounds having a functional group such as a sulfonic acid group, a carboxyl group, and a quaternary ammonium salt.

  In this embodiment, the amount of charge control agent used is determined uniquely by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is uniquely limited. Although it is not a thing, Preferably it is used in 0.1 weight part-10 weight part with respect to 100 weight part of binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the main charge control agent is reduced, the electrostatic attractive force with the developing roller is increased, the flowability of the developer is reduced, and the image density is reduced. Incurs a decline. These charge control agents can be dissolved and dispersed after being melt-kneaded with a masterbatch and resin, and of course, they can be added directly when dissolved and dispersed in an organic solvent, or fixed on the toner surface after preparation of toner particles. May be.

(Resin fine particles)
The resin fine particles used in the present embodiment can be any resin as long as it can form an aqueous dispersion, and may be a thermoplastic resin or a thermosetting resin. For example, vinyl resins, polyurethane resins, epoxy resins Polyester resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate resin and the like. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.

  The vinyl resin is a polymer obtained by homopolymerization or copolymerization of a vinyl monomer, such as a styrene- (meth) acrylate resin, a styrene-butadiene copolymer, a (meth) acrylic acid-acrylate polymer, Examples include styrene-acrylonitrile copolymers, styrene-maleic anhydride copolymers, styrene- (meth) acrylic acid copolymers, and the like. It is preferable that the resin fine particles have a volume average particle size of 5 [nm] to 500 [nm].

(External additive)
As the external additive for assisting the fluidity, developability and chargeability of the colored particles obtained in the present embodiment, inorganic fine particles can be preferably used. The volume average particle diameter of the inorganic fine particles is preferably 5 [nm] to 2 [μm], particularly preferably 5 [nm] to 500 [nm], and further 30 [nm] to 100 [100]. nm]. Since the volume average particle size of the inorganic fine particles is 30 [nm] to 100 [nm], the toner adheres to the rotor 135 and the stator 132 of the Mono pump 131 included in the toner replenishing device 130 while suppressing the deterioration of the fluidity of the toner. Can be suppressed.

Moreover, it is preferable that the specific surface area by BET method is 20 [m < ² > / g]-500 [m < ² > / g]. The use ratio of the inorganic fine particles is preferably 0.01 [wt%] to 5 [wt%] of the toner, and particularly preferably 0.01 [wt%] to 2.0 [wt%]. .

  Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

  In addition, polymer fine particles such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, methacrylic acid ester and acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine and nylon, thermosetting resin And polymer particles.

  Such a fluidizing agent can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .

  Examples of the cleaning performance improver for removing the developer after transfer remaining on the photoreceptor 3 or the primary transfer medium include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, such as polymethyl methacrylate fine particles and polystyrene fine particles. Examples thereof include polymer fine particles produced by soap-free emulsion polymerization. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 [μm] to 1 [μm].

(Production method)
The toner binder can be produced by the following method. Polyol (1) and polycarboxylic acid (2) are produced in the presence of a known esterification catalyst such as tetrabutoxy titanate, dibutyltin oxide, etc., and heated to 150 [° C.] to 280 [° C.] and, if necessary, reduced pressure. Water is distilled off to obtain a polyester having a hydroxyl group. Next, this is reacted with polyisocyanate (3) at 40 [° C.] to 140 [° C.] to obtain a prepolymer (A) having an isocyanate group. Further, (A) is reacted with amines (B) at 0 [° C.] to 140 [° C.] to obtain a polyester modified with a urea bond. When (3) is reacted and (A) and (B) are reacted, a solvent can be used as necessary.

  Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to the isocyanate (3), such as tetrahydrofuran (such as tetrahydrofuran).

  When the unmodified polyester (ii) is used in combination, (ii) is produced by the same method as that for the polyester having a hydroxyl group, and this is dissolved and mixed in the solution after the completion of the reaction (i).

  The dry toner of this embodiment can be manufactured by the following method, but is not limited to these.

(Toner production method in aqueous medium)
As an aqueous medium used in the present embodiment, water alone may be used, but a solvent miscible with water may be used in combination. Examples of the miscible solvent include alcohol (methanol, isopropanol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methylcellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.) and the like.

  The toner particles may be formed by reacting a dispersion composed of a prepolymer (A) having an isocyanate group in an aqueous medium with (B), or using a urea-modified polyester (i) produced in advance. good.

  As a method for stably forming a dispersion comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium, a toner raw material comprising urea-modified polyester (i) or prepolymer (A) in an aqueous medium is used. And a method of dispersing by shearing force.

  The prepolymer (A) and other toner compositions (hereinafter referred to as toner raw materials), a colorant masterbatch, a release agent, a charge control agent, an unmodified polyester resin, etc. are dispersed in an aqueous medium. It may be mixed at the time of formation, but it is more preferable to mix the toner raw materials in advance and then add and disperse the mixture in the aqueous medium.

  In the present embodiment, other toner raw materials such as a colorant, a release agent, and a charge control agent do not necessarily have to be mixed when forming particles in an aqueous medium. It may be added later. For example, after forming particles containing no colorant, the colorant can be added by a known dyeing method.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. In order to make the particle size of the dispersion 2 [μm] to 20 [μm], a high speed shearing method is preferable. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is usually 1000 [rpm] to 30000 [rpm], preferably 5000 [rpm] to 20000 [rpm]. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 minutes to 5 minutes. The temperature at the time of dispersion is usually 0 [° C.] to 150 [° C.] (under pressure), preferably 40 [° C.] to 98 [° C.]. Higher temperatures are preferable in that the dispersion of the urea-modified polyester (i) or prepolymer (A) has a low viscosity and is easily dispersed.

  The amount of the aqueous medium used relative to 100 parts of the toner composition containing the urea-modified polyester (i) and the prepolymer (A) is usually 50 parts by weight to 2000 parts by weight, preferably 100 parts by weight to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner composition is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical. Moreover, a dispersing agent can also be used as needed. It is preferable to use a dispersant because the particle size distribution becomes sharp and the dispersion is stable.

  In the step of synthesizing the urea-modified polyester (i) from the prepolymer (A), the amine (B) may be added and reacted before the toner composition is dispersed in the aqueous medium, or may be dispersed in the aqueous medium. An amine (B) may be added later to cause a reaction from the particle interface. In this case, urea-modified polyester is preferentially generated on the surface of the toner to be produced, and a concentration gradient can be provided inside the particles.

  Anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates and phosphates, alkylamines as dispersants for emulsifying and dispersing the oily phase in which the toner composition is dispersed in a liquid containing water Amine salts such as salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, imidazoline, alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, etc. Nonionic surfactants such as quaternary ammonium salt type cationic surfactants, fatty acid amide derivatives, polyhydric alcohol derivatives, such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl N, amphoteric surfactants such as N- dimethyl ammonium betaine.

  Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount.

  Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [omega-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3 [omega-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carboxylic acid And metal salts, perfluoroalkyl carboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctane sulfonic acid diethanolamide, N-propyl-N- (2 Hydroxyethyl) Fluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned.

  Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (Daikin Kogyo Co., Ltd.), Mega-Fac F-l0, F-l20, F-113, F-191, F-812, F-833 (Dainippon Ink Co., Ltd.), Xtop EF-102 , 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fagento F-100, F150 (manufactured by Neos).

  Examples of cationic surfactants include aliphatic primary, secondary or secondary amine acids having a fluoroalkyl group, aliphatic quaternary ammonium salts such as perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, benza Luconium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass), Florard FC-135 (Sumitomo 3M), Unidyne DS-202 (Daikin Industries) , Megafac F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products Co., Ltd.), Footgent F-300 (Neos Co., Ltd.), and the like.

  Further, tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, hydroxyapatite and the like can be used as an inorganic compound dispersant which is hardly soluble in water.

  Further, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Bodies, such as β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloroacrylate 2-hydroxypropyl, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate, N-meth Tyrol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or esters of compounds containing vinyl alcohol and carboxyl groups, eg acetic acid Vinyl, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic chloride, methacrylic chloride, vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethylene imine, etc. Homopolymers or copolymers such as those having a nitrogen atom or a heterocyclic ring thereof, polyoxyethylene, polyoxypropylene, polyol Siethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester Polyoxyethylenes such as, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  In addition, when an acid such as calcium phosphate salt or an alkali-soluble substance is used as the dispersion stabilizer, the calcium phosphate salt is removed from the fine particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. To do. It can also be removed by operations such as enzymatic degradation.

  When a dispersant is used, the dispersant may remain on the surface of the toner particles. However, it is preferable from the charged surface of the toner that the dispersant is washed and removed after the elongation and / or crosslinking reaction.

  Furthermore, in order to lower the viscosity of the toner composition, a solvent in which the urea-modified polyester (i) or the prepolymer (A) is soluble can be used. The use of a solvent is preferable in that the particle size distribution becomes sharp. The solvent is preferably volatile with a boiling point of less than 100 [° C.] from the viewpoint of easy removal.

  Examples of the solvent include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, Methyl ethyl ketone, methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferable. The usage-amount of the solvent with respect to 100 parts of prepolymers (A) is 0-300 parts normally, Preferably it is 0-100 parts, More preferably, it is 25-70 parts. When a solvent is used, it is removed by heating under normal pressure or reduced pressure after elongation and / or crosslinking reaction.

  The elongation and / or crosslinking reaction time is selected depending on the reactivity depending on the combination of the isocyanate group structure of the prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 hours to 24 hours. It is. The reaction temperature is usually 0 [° C.] to 150 [° C.], preferably 40 [° C.] to 98 [° C.]. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

  In order to remove the organic solvent from the obtained emulsified dispersion, a method in which the temperature of the entire system is gradually raised to completely evaporate and remove the organic solvent in the droplets can be employed. Alternatively, the emulsified dispersion can be sprayed into a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, and the aqueous dispersant can be removed by evaporation together. . As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, in particular, various air currents heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used is generally used. Sufficient quality can be obtained with a short treatment such as spray dryer, belt dryer or rotary kiln. When the particle size distribution at the time of emulsification dispersion is wide and washing and drying processes are performed while maintaining the particle size distribution, the particle size distribution can be adjusted by classifying into a desired particle size distribution.

  In the classification operation, the fine particle portion can be removed in the liquid by a cyclone, a decanter, centrifugation, or the like. Of course, the classification operation may be performed after obtaining the powder as a powder after drying. The unnecessary fine particles or coarse particles obtained can be returned to the kneading step and used for the formation of particles. At that time, fine particles or coarse particles may be wet.

  The dispersant used is preferably removed from the obtained dispersion as much as possible, but it is preferable to carry out it simultaneously with the classification operation described above.

  The resulting dried toner powder is mixed with dissimilar particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or mechanical impact force is applied to the mixed powder. As a result, it is possible to prevent the dissociation of the foreign particles from the surface of the composite particle obtained by immobilizing and fusing on the surface.

  Specific means include a method of applying an impact force to the mixture by blades rotating at high speed, a method of injecting and accelerating the mixture in a high-speed air stream, and causing particles or composite particles to collide with an appropriate collision plate, etc. is there. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) is modified to reduce the grinding air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron system (Made by Kawasaki Heavy Industries, Ltd.), automatic mortar and the like.

(Carrier for two components)
When the toner of this embodiment is used for a two-component developer, it may be used by mixing with a magnetic carrier, and the content ratio of the carrier and the toner in the developer is 1 part by weight of the toner with respect to 100 parts by weight of the carrier. -10 parts by weight is preferred.

  As the magnetic carrier, conventionally known ones such as iron powder, ferrite powder, magnetite powder, magnetic resin carrier having a particle size of about 20 [μm] to 200 [μm] can be used. Examples of the coating material include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Polyvinyl and polyvinylidene resins such as acrylic resins, polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, polystyrene resins and styrene acrylic copolymer resins, Halogenated olefin resin such as vinyl chloride, polyester resin such as polyethylene terephthalate resin and polybutylene terephthalate resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexa Fluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and vinyl fluoride, tetrafluoroethylene and vinylidene fluoride Fluoro such as terpolymers of emission and non-fluoride monomers including, and silicone resins.

  Moreover, you may make conductive powder etc. contain in coating resin as needed. As the conductive powder, metal powder, carbon black, titanium oxide, tin oxide, zinc oxide or the like can be used. These conductive powders preferably have an average particle size of 1 [μm] or less. When the average particle diameter is larger than 1 [μm], it is difficult to control the electric resistance.

  Here, in order to prevent carrier adhesion, generally, a high resistance carrier having an electric resistance of 12 [Log Ω · cm] to 14 [Log Ω · cm] is used. It is known that even in the combination, image unevenness called “deep tip” is worsened. As described above, when zinc stearate is added to the toner of a developer using a high-resistance carrier, density unevenness called “deep tip” may easily occur instead of suppressing carrier adhesion. was there.

  In the present embodiment, the electric resistance (LogR) of the carrier used is 11.0 [Ω · cm] to 15.7 [Ω · cm] (in the case of an applied electric field strength of 1000 [V / cm]) or less. preferable. The inventors of the present application have confirmed that a carrier having an electric resistance of 15.7 [Log Ω · cm] can form a good image without causing a problem with the edge effect. Therefore, by setting the carrier resistance to 15.7 [Log Ω · cm] or less, the edge effect is not caused, and the effect of suppressing the occurrence of density unevenness called “deep tip” can be obtained.

  Conventionally, it has been known that carrier adhesion to the photosensitive member 3 becomes a problem in the case of a low resistance carrier. Therefore, a high resistance carrier having an electric resistance of 10.0 [Log Ω · cm] or more is used. Yes. Here, in the case of a carrier having an electric resistance of 10.0 [Log Ω · cm], the tip end density is hardly deteriorated even if the ta-C coating is not formed on the surface of the developing sleeve (toner concentration 9 [%], particle size). Experiment with toner having a diameter of 5.2 [μm]). However, in the case of a carrier having an electrical resistance of 11.0 [Log Ω · cm], the tip of the image having an ID of about 0.02 to 0.05 becomes dark unless the ta-C film is formed on the surface of the developing sleeve. Therefore, when a carrier having a carrier resistance of 11.0 [Log Ω · cm] or more is used, the formation of a ta-C coating on the surface of the developing sleeve is particularly effective in suppressing density unevenness called “deep tip”. Is preferred.

  In addition, carrier resistance was measured using ADVANTEST ULTRA HIGHIRISTANCE METER R8340A.

[Experiment]
The image forming apparatus according to this embodiment continuously outputs 300,000 sheets of images, and replaces only the developing sleeve of the developing device in which the two-component developer having the toner and the magnetic carrier with the externally added zinc stearate is deteriorated. A solid image was output. As the developing sleeve to be replaced, the developing sleeves of Example 1, Example 2, Example 3 and Comparative Example were used.

[Example 1]
<Development sleeve>
Base material: Aluminum Surface layer covering the base material: Molybdenum sulfide (MoS ₂ ) coating

[Example 2]
<Development sleeve>
Base material: Aluminum Surface layer covering the base material: ta-C coating

[Example 3]
<Development sleeve>
Development sleeve substrate: Aluminum Surface layer covering substrate: Tin plating

<Comparative example>
Development sleeve substrate: Aluminum Surface layer covering substrate: None

  Then, when the solid image was output, the image density ID of the area corresponding to one rotation of the developing sleeve, which is the leading end area of the solid image, and the image density ID of the area after the second rotation of the developing sleeve were measured. FIG. 1 shows the degree of density unevenness called “deep tip”, and shows the difference between the image density ID of the area corresponding to one round of the developing sleeve and the image density ID of the area after the second round of the developing sleeve. The vertical axis of the graph shown in FIG. Then, it can be said that the density unevenness called “deep tip” is reduced as the ID difference is reduced, and the density unevenness called “deep tip” is worsened as the ID difference is increased.

  As can be seen from FIG. 1, by using the developing sleeves of Example 1, Example 2 and Example 3, the ID difference can be made smaller than when the developing sleeve of the comparative example is used. Density unevenness called "" can be reduced.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A developing device 7 having a developer carrying member such as a developing roller 12 carrying a developer containing toner to which a fatty acid metal salt is externally added on the surface of a developing sleeve such as a developing sleeve 15 provided rotatably. In the developing device, as the developing sleeve, a substrate in which a surface layer such as a coating 15b made of a substance having a smaller adhesion force to the toner than the substrate is applied to a substrate such as the substrate 15a of the developing sleeve. According to this, as described in the above embodiment, it is possible to reduce density unevenness while suppressing cleaning failure.
(Aspect B)
In (Aspect A), the developer is a developer containing the toner and a magnetic carrier, and the developer carrier includes a magnetic field generating means having a plurality of magnetic poles inside the developing sleeve, and the magnetic field generating means The developer is caused to stand on the surface of the developing sleeve by the magnetic field generated by. According to this, it is possible to reduce density unevenness while suppressing poor cleaning.
(Aspect C)
In (Aspect A) or (Aspect B), the surface layer is preferably a DLC (diamond-like carbon) film.
(Aspect D)
In (Aspect C), the DLC is preferably ta-C (tetrahedral amorphous carbon).
(Aspect E)
In (Aspect D), the ta-C film was formed on the surface of the developing sleeve using the FCVA method. According to this, as described in the above embodiment, a hard and thin coating can be easily created.
(Aspect F)
In (Aspect A) or (Aspect B), the surface layer is preferably a molybdenum sulfide film.
(Aspect G)
In (Aspect A) or (Aspect B), the surface layer is preferably tin-plated.
(Aspect H)
In (Aspect A) or (Aspect B), the surface layer is preferably an Al ₂ O ₃ coating.
(Aspect I)
In (Aspect B), (Aspect C), (Aspect D), (Aspect E), (Aspect F), (Aspect G) or (Aspect H), the electric resistance (LogR) of the magnetic carrier used is 11.0. [Ω · cm] to 15.7 [Ω · cm] (in the case of applied electric field strength of 1000 [V / cm]) or less. According to this, good image formation can be performed as described in the above embodiment.
(Aspect J)
In (Aspect A), (Aspect B), (Aspect C), (Aspect D), (Aspect E), (Aspect F), (Aspect G), (Aspect H) or (Aspect I), the volume of the toner The average particle size is preferably 5.8 [μm] or less.
(Aspect K)
In (Aspect A), (Aspect B), (Aspect C), (Aspect D), (Aspect E), (Aspect F), (Aspect G), (Aspect H), (Aspect I) or (Aspect J) The fatty acid metal salt is zinc stearate. According to this, as described in the above embodiment, good cleaning property, environmental stability, and charging property can be obtained.
(Aspect L)
In (Aspect K), the toner to be used dissolves or / and disperses a toner composition containing a modified polyester resin capable of reacting with a compound having an active hydrogen group in an organic solvent, and the solution or dispersion is used as resin fine particles. A toner for image formation characterized in that a toner binder contains a crystalline polyester resin together with the modified polyester resin in a toner obtained by reacting with a compound having an active hydrogen group in an aqueous medium containing The toner binder contains, together with the modified polyester resin (i), an unmodified polyester resin (ii) and a crystalline polyester resin (iii), and the weight of (i) and (ii) + (iii) The ratio of 5/95 to 25/75 and the weight ratio of (ii) to (iii) is 99/1 to 50/50; / 2 outlet temperature is at 110 [° C.] or less, zinc stearate to be added is 0.05 wt% or more. According to this, as described in the above embodiment, it is possible to reduce the power consumption by lowering the fixing temperature.
(Aspect M)
In (Aspect K) or (Aspect L), the zinc stearate to be added is 0.30 [wt%] or less. According to this, as explained about the above-mentioned embodiment, it can control that background dirt arises.
(Aspect N)
An image carrier such as the photosensitive member 3; a charging unit such as a charging device 5 that charges the image carrier; a latent image forming unit such as an optical writing unit 20 that forms a latent image on the image carrier; and an image carrier. Developing means such as a developing device 7 that develops the latent image on the image with toner, transfer means such as a transfer unit 80 that finally transfers the toner image on the image carrier to a recording medium, and on the image carrier after transfer In the image forming apparatus including the cleaning unit such as the drum cleaning device 4 that removes the transfer residual toner remaining on the developing unit, the developing unit includes (Aspect A), (Aspect B), (Aspect C), and (Aspect D). , (Aspect E), (Aspect F), (Aspect G), (Aspect H), (Aspect I), (Aspect J), (Aspect K), (Aspect L) or (Aspect M) It was. According to this, as described in the above-described embodiment, it is possible to suppress the occurrence of density unevenness called dark front end while suppressing poor cleaning of the surface of the image carrier by the cleaning unit, and it is possible to perform good image formation.

DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Photoconductor unit 3 Photoconductor 4 Drum cleaning apparatus 5 Charging apparatus 6 Charging roller 7 Developing apparatus 8 First conveying screw 9 First agent storage part 10 Toner density sensor 11 Second conveying screw 12 Developing roller 13 Doctor blade 14 Second agent container 15 Developing sleeve 15a Base material 15b Film 16 Magnet roller 19 Toner bottle 20 Optical writing unit 31 First paper feed cassette 31a First paper feed roller 32 Second paper feed cassette 32a Second paper feed roller 33 Supply Paper path 34 Conveying roller pair 35 Registration roller pair 41 Cleaning blade 42 Brush roller 43 Lubricant leveling blade 50 Secondary transfer roller 60 Fixing unit 61 Pressure heating roller 61a Heat source 62 Fixing belt unit 63 Heating roller 63a Heat source 64 Fixing belt 65 Tension roller 66 Drive roller 67 Discharge roller pair 68 Stack unit 80 Transfer unit 81 Intermediate transfer belt 82 Belt cleaning unit 82a Cleaning blade 83 First bracket 84 Second bracket 85 Primary transfer roller 86 Secondary transfer backup roller 87 Driving roller 88 Auxiliary roller 89 Tension roller 106 Through hole 109 Case 120 Inlet opening 121 Outlet opening 130 Toner supply device 131 Mono pump 132 Stator 133 Suction port 134 Drive shaft 135 Rotor 136 Motor 138 Toner transport pipe 139 Tube 142 Nozzle member 191 Nail member 191 Bottle Portion 191a Protrusion 192 Cap portion 192a Toner discharge port 192b Hole portion 193 Plug member

JP 2000-19773 A

Claims (14)

In a developing device provided with a developer carrier that carries a developer containing toner to which a fatty acid metal salt is externally added on the surface of a developing sleeve that is rotatably provided,
A developing device comprising a developing sleeve coated with a surface layer made of a substance having a lower adhesion to toner than the base material of the base material of the developing sleeve. The developing device according to claim 1.
The developer is a developer containing the toner and a magnetic carrier,
The developer carrier includes magnetic field generating means having a plurality of magnetic poles inside the developing sleeve, and the developer is supported on the surface of the developing sleeve by the magnetic field generated by the magnetic field generating means. A developing device. The developing device according to claim 1 or 2,
The developing device, wherein the surface layer is a DLC film. The developing device according to claim 3.
The developing device according to claim 1, wherein the DLC is ta-C. The developing device according to claim 4.
A developing apparatus, wherein the ta-C film is formed on the surface of the developing sleeve by using FCVA method. The developing device according to claim 1 or 2,
A developing device wherein the surface layer is a molybdenum sulfide coating. The developing device according to claim 1 or 2,
The developing device according to claim 1, wherein the surface layer is tin-plated. The developing device according to claim 1 or 2,
The developing device, wherein the surface layer is an Al ₂ O ₃ coating. The developing device according to claim 2, 3, 4, 5, 6, 7, or 8.
The developing device characterized in that the electric resistance (LogR) of the magnetic carrier is 11.0 [Ω · cm] to 15.7 [Ω · cm] (in the case of applied electric field strength of 1000 [V / cm]) or less. . The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9.
A developing device, wherein the toner has a volume average particle size of 5.8 [μm] or less. The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
A developing device wherein the fatty acid metal salt is zinc stearate. The developing device according to claim 11.
The toner dissolves or / and disperses a toner composition containing a modified polyester resin capable of reacting with a compound having an active hydrogen group in an organic solvent, and the solution or dispersion is dissolved in an aqueous medium containing resin fine particles. In the toner obtained by reacting with a compound having an active hydrogen group, the toner binder contains a crystalline polyester resin together with the modified polyester resin.
The toner binder contains an unmodified polyester resin (ii) and a crystalline polyester resin (iii) together with the modified polyester resin (i), and the weight ratio of (i) to (ii) + (iii) is 5/95 to 25/75, and the weight ratio of (ii) and (iii) is 99/1 to 50/50,
T1 / 2 outflow temperature of the toner is 110 [° C.] or less,
A developing device characterized in that zinc stearate to be added is 0.05 [% by weight] or more. The developing device according to claim 11 or 12,
The developing device according to claim 1, wherein the zinc stearate to be added is 0.30 [wt%] or less. An image carrier;
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the image carrier;
Developing means for developing the latent image on the image carrier with toner;
Transfer means for finally transferring the toner image on the image carrier to a recording medium;
In an image forming apparatus provided with a cleaning unit that removes transfer residual toner remaining on the image carrier after transfer,
An image forming apparatus using the developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13.

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