JP2008129128A - Developing device, process cartridge and image forming apparatus equipped with the same and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which avoids faulty scooping of developer by a stirring conveyance means and can form a high-quality image. <P>SOLUTION: The developing device has: a partition wall 47Y which divides a housing section housing developer into two to form first and second supply sections; a first conveyance screw 43Y in the first supply section; a second conveyance screw 44Y in the second supply section; a developing roller 42Y which is disposed above and adjacently to the first conveyance screw 43Y and supplies developer conveyed by the first and second conveyance screws to a photoreceptor 11Y to develop an electrostatic latent image; and a regulation blade 45Y which is disposed above the developing roller and regulates the layer thickness of developer, wherein a layer thickness regulation member 50Y which comes in contact with developer moving along the developing roller 42Y and on the upper side of the first conveyance screw 43Y and regulates the layer thickness of developer in the first supply section is attached to the partition wall 47Y, and the cross-sectional area of blades of the first conveyance screw is made larger than that of blades of the second conveyance screw. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus for recording an image formed on a latent image carrier on a recording medium using an electrophotographic system including a copying machine using a laser, a printer, a facsimile, or a combination machine combining them. The present invention relates to a developing device to be applied, a process cartridge and an image forming apparatus including the developing device, and an image forming method using the same.

2. Description of the Related Art Conventionally, a two-component development method using a two-component developer composed of a nonmagnetic toner and a magnetic carrier has been widely used as a method for revealing an electrostatic latent image formed on an image carrier. In the two-component developing device applied to this developing method, toner is replenished from a toner supply unit provided separately. The toner is stirred by a stirring means in the developing device and is carried on a developer carrier (developing roller), and the electrostatic latent image on the image carrier is visualized using this developer. The toner from the toner supply unit is carried on the developing roller while being sufficiently agitated and conveyed by the agitating means. However, if the amount of the developer is too small, the height of the developer surface is lowered, and the toner is not supplied to the developing roller. Insufficient screw pitch unevenness as agitating and conveying means may affect the image. In order to prevent such inconvenience, in recent years, even if the amount of the developer is increased and the height of the surface of the developer is increased, a developer storage space is provided in the developing device and the developer is stored in advance in the developing device. However, there is a limit to the amount thereof, and it is difficult to secure an amount of developer sufficient to make the surface of the agent sufficiently high.

  As a conventional technique related to such a developing device, for example, in Patent Document 1, the toner supplied in the developer container and the developer (carrier) are sufficiently mixed and agitated to uniformly distribute the toner in the developer. Is an apparatus developed for the purpose of providing an apparatus that forms an image without density unevenness and toner scattering by distributing the toner to the developer, and the developer on the upstream side in the rotation direction of the transport screw in the developer container A developing device is disclosed in which a toner guide for guiding the toner is provided in the vicinity of a toner supply port of the developer container.

JP 2004-069789 A

However, since the technique described in Patent Document 1 is configured to supply toner into the developer, the amount of toner taken in varies depending on the height (pressure) of the agent surface. Further, since the height of the surface of the developer cannot be sufficiently maintained because of the space in the developer carrier and the conveying screw, there is a problem that screw pitch unevenness is likely to occur.
Recently, there are many developing devices in which the developing roller pumps up and holds a small amount of developer in order to reduce the torque of the developing device or reduce the stress on the developer. However, in the case of such an apparatus, the influence of the shake of the first stirring means is likely to appear remarkably, and when the first stirring means having a bad shake or the like is used, an abnormal image such as screw pitch unevenness appears. There's a problem. In particular, due to the strength of the stirring means, the influence of the shake is likely to occur, and the influence of the shake appears remarkably in the central portion of the stirring means that is easily bent.
The present invention has been made in view of the above-described problems of the prior art, and its problem is to eliminate poor developer pumping (pitch unevenness) by the developer agitating and conveying means and to form a high-quality image. An object of the present invention is to provide a highly reliable developing device that can be used. Another object of the present invention is to provide a process cartridge and an image forming apparatus provided with such a developing device, and an image forming method to which these are applied.

In order to solve the above-described problems, a developing device according to the present invention includes a partition wall that divides a developer accommodating portion that accommodates a developer into two parts to form a first supply portion and a second supply portion, and an inside of the first supply portion. A first agitation unit provided in the second supply unit, a second agitation unit provided in the second supply unit, and a first agitation unit adjacent to the first supply unit of the first supply unit. (2) A developer carrying member for supplying the developer conveyed by the agitating means to the photosensitive member to develop the electrostatic latent image on the photosensitive member, and a developer carrying member disposed above the developer carrying member. And a regulating blade that regulates the layer thickness of the developer to be brought into contact with the developer that moves above the first stirring means along the developer carrier on the partition wall, 1 Install a layer thickness regulating member that regulates the layer thickness of the developer in the supply section. The cross-sectional area of the screw blade of the first stirring means, characterized in that the sectional area of the screw blades of the second agitating means.
In this case, it is preferable that the shaft diameter of the central portion of the rotation shaft of the first stirring means is larger than the shaft diameters of both end portions.
Moreover, it is preferable to provide a taper part in which an axial diameter changes one by one between the central part with a large shaft diameter of the rotating shaft of the first stirring means and both end parts with a thin shaft diameter.

The process cartridge according to the present invention includes an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a development region that bears a developer on the developer carrier and faces the image carrier. A developing device that develops the electrostatic latent image on the image carrier to form a toner image, and a transfer residual toner remaining on the image carrier after the developed toner image is transferred to a transfer material. In a process cartridge which is applied to an image forming apparatus having a cleaning device to be removed, and in which the image carrier and at least the developing device are integrated and detachably formed on the image forming apparatus main body, the developing device is Any one of the developing devices described above is characterized.
In addition, an image forming apparatus according to the present invention includes an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, a developer carried on a developer carrier, and opposed to the image carrier. And a developing device that develops the electrostatic latent image on the image carrier and converts it into a toner image by transferring it to a developing area, and transfers the developed toner image onto a transfer material and then remains on the image carrier In the image forming apparatus having a cleaning device for removing residual toner, the developing device is any one of the developing devices described above or a developing device constituting the process cartridge.

In the image forming method of the present invention, toner and magnetic particles are used as a developer in any one of the developing devices described above, the image forming device including the process cartridge described above, or the image forming method using the image forming device. It is characterized by using a two-component developer containing.
In this case, the particle size of the magnetic particles is preferably 20 to 50 μm.
The magnetic particles are preferably obtained by coating a core material made of a magnetic material with a resin coating film containing a resin component obtained by crosslinking a thermoplastic resin and a melanin resin and a charge control agent.
Further, the toner is obtained by crosslinking and / or crosslinking a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent in an organic solvent is dispersed in an aqueous medium. A toner obtained by an extension reaction is preferable.
Furthermore, the toner has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) in the range of 1.00 to 1.40. It may be in.
Furthermore, the toner may have a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.
Furthermore, the toner has a substantially spherical shape, and the shape is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), and the major axis r1 and minor axis r2. And the ratio (r3 / r2) of the thickness r3 to the minor axis r2 is in the range of 0.7 to 1.0. can do.

According to the developing device of the present invention, the layer thickness of the developer in the first supply unit is stable and the defective image is eliminated, and the rotation shaft of the first conveying screw is difficult to bend, the shake is improved, and the central portion in the longitudinal direction is improved. The adverse effect on the pumping up of the developer can be reduced.
According to the process cartridge of the present invention, the layer thickness of the developer in the first supply unit is stabilized and defective images are eliminated, and the rotation shaft of the first conveying screw is difficult to be bent, and the adverse effect on the pumping of the developer is reduced. . In addition, maintainability is improved and the current state can be easily restored in the event of a failure.
According to the image forming apparatus of the present invention, the layer thickness of the developer in the first supply unit in the developing device is stabilized, and the rotating shaft of the first conveying screw is difficult to be bent, so that a defective image is eliminated and a high-quality image is obtained. It can be formed stably.
According to the image forming method of the present invention, uneven development can be eliminated, and a high-quality image excellent in dot reproducibility can be stably formed for a long period of time.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of a laser printer as an image forming apparatus according to an embodiment of the present invention.
In FIG. 1, four sets of toner image forming portions 1Y for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K) are provided at the substantially central portion of the laser printer. 1M, 1C, and 1K (hereinafter, the subscripts Y, M, C, and K of the respective symbols indicate members for yellow, magenta, cyan, and black, respectively). The toner image forming units 1Y, 1M, 1C, and 1K are sequentially arranged from the upstream side in the moving direction of the transfer paper 100 (the direction in which the belt 60 travels along the arrow A in the drawing). The toner image forming units 1Y, 1M, 1C, and 1K are provided with photosensitive drums 11Y, 11M, 11C, and 11K as image carriers and a developing unit, respectively. The toner image forming units 1Y, 1M, 1C, and 1K are arranged so that the rotation axes of the photosensitive drums are parallel to each other and arranged at a predetermined pitch in the transfer paper moving direction.

In addition to the toner image forming units 1Y, 1M, 1C, and 1K, the laser printer carries the optical writing unit 2, the paper feed cassettes 3, 4, the resist roller pair 5, and the transfer paper 100 to carry each toner image. A transfer unit 6 as a belt driving device having a transfer conveyance belt 60 as a transfer conveyance member that conveys the transfer position so as to pass through a transfer position of the forming unit, a fixing unit 7 of a belt fixing system, a paper discharge tray 8, and the like are provided. .
Further, this laser printer is provided with a manual feed tray MF and a toner replenishing container TC, and a waste toner bottle, a duplex / reversing unit, a power supply unit, etc. (not shown) are also provided in a space S indicated by a two-dot chain line. ing. A one-dot chain line in FIG. 1 indicates a conveyance path of the transfer paper 100.
The optical writing unit 2 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photosensitive drums 11Y, 11M, 11C, and 11K while scanning the laser beam based on the image data. An electrostatic latent image is formed.

In the laser printer having such a configuration, the transfer paper 100 fed from the paper feed cassettes 3 and 4 or the manual feed tray MF is transported by a transport roller while being guided by a transport guide (not shown), and a registration roller pair 5 is provided. Sent to the paused position. The transfer paper 100 delivered at a predetermined timing by the registration roller pair 5 is carried on the transfer conveyance belt 60, conveyed toward the toner image forming units 1Y, 1M, 1C, and 1K, and passes through the transfer nips. .
The toner images developed on the toner drums 11Y, 11M, 11C, and 11K of the toner image forming portions 1Y, 1M, 1C, and 1K are superimposed on the transfer paper 100 at the transfer nips, respectively, and transferred electric fields and nip pressures. Is transferred onto the transfer paper 100 in response to the above action. By this superposition transfer, a full-color toner image is formed on the transfer paper 100. The surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K after the toner image transfer are cleaned by a cleaning device, and are further discharged to prepare for the formation of the next electrostatic latent image.
On the other hand, the transfer paper 100 on which the full color toner image has been transferred is fixed in the first paper discharge direction B corresponding to the rotational posture of the switching guide G after the full color toner image is fixed by the downstream fixing unit 7. Or, it goes in the second paper discharge direction C. When the paper is discharged from the first paper discharge direction B onto the paper discharge tray 8, it is stacked in a so-called face-down state in which the image surface is on the lower side. On the other hand, when the paper is discharged in the second paper discharge direction C, it is conveyed toward another post-processing device (not shown) (such as a sorter or a binding device) or again for double-sided printing via a switchback unit. It is conveyed to the registration roller pair 5.

Next, the developing device of FIG. 1 will be described in detail.
FIG. 2 is a cross-sectional view showing the developing device in the toner image forming unit of FIG.
In FIG. 2, the developing device 40Y is provided with a developing roller 42Y as a developer carrying member disposed so as to be partially exposed from the opening of the casing. The first supply unit in the casing is provided with a first transfer screw 43Y, the second supply unit is provided with a second transfer screw 44Y, a regulation blade 45Y, a toner concentration sensor (hereinafter referred to as T sensor) 46Y, and the like. Is provided. The regions where the first transport screw 43Y and the second transport screw 44Y are respectively provided are partitioned by a partition wall 47Y. That is, the partition wall 47Y partitions the first supply unit provided with the developing roller 42Y and the first conveyance screw 43Y and the second supply unit provided with the second conveyance screw 44Y within the casing.
A two-component developer 49Y containing magnetic particles (hereinafter also referred to as a magnetic carrier) and negatively chargeable Y toner is accommodated in the casing of the developing device. The two-component developer 49Y is frictionally charged while being agitated and conveyed by the first conveying screw 43Y and the second conveying screw 44Y, and then carried on the surface of the developing roller 42Y. Then, after the layer thickness is regulated by the regulating blade 45Y, it is conveyed to the developing area facing the photoreceptor 11Y, and Y toner is attached to the electrostatic latent image on the photoreceptor 11Y. This adhesion forms a Y toner image on the photoreceptor 11Y. The two-component developer whose Y toner has been consumed by the development is returned into the casing as the developing roller 42Y rotates.

The first transport screw 43Y is rotationally driven by a driving unit (not shown) and supplies the two-component developer in the first supply unit to the developing roller 42Y while transporting from the front side to the back side in the drawing. The two-component developer conveyed to the vicinity of the end of the first supply unit by the first conveyance screw 43Y enters the second supply unit through an opening (not shown) provided in the partition wall 47Y. In the second supply unit, the second transport screw 44Y is rotationally driven by a driving unit (not shown), and transports the two-component developer sent from the first supply unit in a direction opposite to the first transport screw 43Y. The two-component developer conveyed to the vicinity of the end of the second supply unit by the second conveyance screw 44Y returns to the first supply unit through the other opening (not shown) provided in the partition wall 47Y.
The T sensor 46Y including a magnetic permeability sensor is provided on the bottom wall near the center of the second supply unit, and outputs a voltage having a value corresponding to the magnetic permeability of the two-component developer passing therethrough. Since the magnetic permeability of the two-component developer has a certain degree of correlation with the toner concentration, the T sensor 46Y outputs a voltage having a value corresponding to the Y toner concentration. This output voltage value is sent to a control unit (not shown). The control unit includes a RAM, in which Y Vtref that is a target value of the output voltage from the T sensor 46Y is stored. In addition, data for M voltage Vtref, C voltage Vtref, and K voltage Vtref, which are target values of output voltage from a T sensor (not shown) mounted in another developing device, are also stored. The Y Vtref is used for driving control of a Y toner conveying device (not shown). Specifically, the control unit drives and controls a Y toner conveyance device (not shown) so that the value of the output voltage from the T sensor 46Y approaches the V Vref for Y, and replenishes Y toner into the second supply unit. By this replenishment, the Y toner density of the two-component developer 49Y in the developing device 40Y is maintained within a predetermined range. Similar toner replenishment control is performed for the developing devices of the other process cartridges.

Next, the characteristic part in this embodiment is demonstrated in detail.
FIG. 3 is a cross-sectional view showing a specific configuration of the developing device which is a characteristic part of the present embodiment.
In FIG. 3, the developing device applied to the image forming apparatus according to the present embodiment has a first supply at a position in contact with the developer moving along the developing roller 42 </ b> Y above the first conveying screw 43 </ b> Y. A layer thickness regulating member 50Y that regulates the layer thickness of the developer in the room is provided. The layer thickness regulating member 50Y is fixed to the partition wall 47Y, for example.
In a state where the layer thickness regulating member 50Y is not present (for example, FIG. 2), as shown in FIGS. 4A and 4B, the height of the developer surface becomes uneven at the conveying screw pitch, and is greatly waved. become. FIG. 4A is a cross-sectional view taken along the rotation axis of the first conveying screw 43Y in the prior art, and FIG. 4B is a cross-sectional view perpendicular to the rotation axis. In FIG. 4, the layer thickness of the developer in the first supply unit is affected by the screw pitch and undulates up and down. For this reason, the amount of the developer carried and moved on the developing roller is affected by the portion where the screw of the first conveying screw 43Y is present and the portion where the screw is not present, and unevenness occurs in the thickness of the developer layer on the developing roller.
As shown in FIGS. 3A and 3B, the apparatus according to the present embodiment is provided with the developer layer thickness regulating member 50Y. As shown in FIGS. Less affected by screw. Even if it is affected by the screw, the developer carried on the developer carrier and the layer thickness regulating member at the closest portion 50aY (see FIG. 3) with the developing roller 42Y of the layer thickness regulating member 50Y. Since it is configured so as to be in contact with 50Y, the developer layer thickness unevenness (screw pitch unevenness) can be leveled with the layer thickness regulating shape 50Y. FIG. 5A is a cross-sectional view taken along the rotation axis of the first transport screw 43Y in the present embodiment, and FIG. 5B is a cross-sectional view perpendicular to the rotation axis. In FIG. 5, the layer height of the developer in the first supply unit is higher than the layer thickness of the prior art, and is hardly affected by the screw pitch.
The layer thickness regulating member 50Y is attached to the partition wall 47Y of the developing case with double-sided tape, for example. Therefore, a shape that optimizes the GAP at the closest portion with the developer carrier of the regulating member can be arbitrarily selected depending on the amount of the developer.

FIG. 6 is an explanatory diagram showing the configuration of the conveying screws 43Y and 44Y as the stirring means in FIG. Hereinafter, the characteristic part of the apparatus of this embodiment will be described with reference to FIG. 6 in comparison with the prior art shown in FIG.
FIG. 7 is an explanatory diagram showing a first transport screw 43Y and a second transport screw 44Y in the prior art.
In FIG. 7, in the prior art, the shaft diameters, screw cross-sectional areas, and screw pitches of the first transport screw 43Y and the second transport screw 44Y are substantially the same, so the volumes are substantially equal, and the developer transport speed is the same. Were almost equal.
On the other hand, in the present embodiment (FIG. 6), the thickness of the screw blades of the first transport screw 43Y is thicker than the thickness of the screw blades of the second transport screw 44Y. In other words, in the present embodiment, the cross-sectional shape of the screw of the first transport screw 43Y is made larger than the cross-sectional shape of the screw of the second transport screw 44Y. By providing the layer thickness regulating member 50Y, the developer in the first supply unit passes through the closest portion 50aY (see FIG. 3), so that the agent pressure in the vicinity increases. When the agent pressure increases, the central portion in the longitudinal direction of the first conveying screw 43Y becomes easy to bend, and if the agent pressure rotates, the unevenness of the agent surface increases. In order to prevent the bending of the first conveying screw 43Y, it is necessary to increase the strength of the screw. By increasing the screw cross-sectional area of the first conveying screw 43Y, the strength of the first conveying screw 43Y is increased, so that the shaft is difficult to bend and the runout is improved, and the adverse effect on the pumping of the developer is reduced.
On the other hand, the second conveying screw 44Y does not need to be as strong as the first conveying screw 43Y, and even if the surface of the agent becomes uneven, there is no adverse effect on the image, so there is no need to increase the screw cross-sectional area. It should be noted that increasing the screw cross-sectional area of the second conveying screw 44Y results in excessive quality and increases the part cost.

The image forming apparatus according to the present embodiment includes an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a developer that carries the developer on the developer carrier and faces the image carrier. A developing device that transports the toner image to a region and develops the latent image on the image carrier to form a toner image, and removes transfer residual toner remaining on the image carrier after the developed toner image is transferred to a transfer material In the image forming apparatus having the cleaning device, the developing device shown in FIG. 3 is used as the developing device. According to this embodiment, the developing roller 42Y is placed on the upper side of the first conveying screw 43Y. A layer thickness regulating member 50Y that regulates the layer thickness of the developer in the first supply unit is provided at a position in contact with the moving developer, and the cross-sectional area of the conveyance unit of the first conveyance screw 43Y, that is, the screw blade is set to the first. 2 of transport screw 44Y By making it larger than the cross-sectional area of the screw blade that is the feeding part, the layer thickness of the developer in the first supply part is stabilized and the defective image is eliminated, the deflection of the first conveying screw is eliminated, and the vibration is improved, The adverse effect on the pumping up of the developer in the center in the longitudinal direction is reduced.
In addition, according to the present embodiment, the development pitch unevenness image is generated by the effect of smoothing the developer pumping failure (pitch unevenness) by the conveying screw as the stirring means by the regulating member and the effect of strengthening the developer stirring by the regulating member. It will be a highly reliable device.

In the present embodiment, the developing device 40 is preferably integrated with the photoconductor 11 to form a process cartridge. The process cartridge includes an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a developer that is carried on the developer carrier and conveyed to a development area that faces the image carrier. A developing device that develops a latent image on the image carrier into a toner image, and a cleaning device that removes transfer residual toner remaining on the image carrier after the developed toner image is transferred to a transfer material. The image forming apparatus includes the image carrier and the developing device, and supports the charging device and / or the cleaning device integrally as necessary, and is detachable from the image forming apparatus main body. Formed. Note that the developing device of FIG. 3 is applied to the process cartridge as a developing device.
FIG. 8 is a schematic diagram showing a schematic configuration of the process cartridge.
In FIG. 8, this process cartridge mainly comprises a charging unit 105, a developing unit 106, a photoconductor 107, and a cleaning unit 108.
In the image forming apparatus provided with the process cartridge using the developing device of FIG. 3, the photosensitive member is rotationally driven at a predetermined peripheral speed. In the rotation process, the photosensitive member is charged uniformly with positive or negative predetermined potential on its peripheral surface by the charging means, and then receives image exposure light from image exposure means such as slit exposure and laser beam scanning exposure, thereby Then, electrostatic latent images are sequentially formed on the peripheral surface of the photoreceptor. The formed electrostatic latent image is developed with toner by the developing unit, and the developed toner image is fed from the paper feeding unit between the photosensitive member and the transferring unit in synchronization with the rotation of the photosensitive member. Then, the images are sequentially transferred by the transfer means. The transfer material that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means, and fixed, and printed out as a copy (copy). The surface of the photoconductor after the image transfer is cleaned by removing the transfer residual toner by a cleaning means, and after being discharged, it is repeatedly used for image formation.

According to the image forming apparatus including the process cartridge to which the developing device of FIG. 3 is applied, similarly to the above-described embodiment, the image forming apparatus has a regulating member that regulates the amount of developer on the developing roller above the developing roller, A first agitating means for conveying the developer while agitating; a second agitating means provided on the opposite side of the developer carrier relative to the first agitating means; and the first and second agitating means. In the developing device having a partition wall therebetween, the developer layer thickness regulating member 50 is placed on the partition wall 47 at a position in contact with the developer moving on the developer carrier above the first stirring means. Since the rotation shaft of the first conveying screw is reinforced (see FIG. 6), the shaft does not bend due to the stirrer reinforcing effect, the run-out is improved, and the developer at the central portion in the longitudinal direction is improved. Low adverse effect on pumping At the same time, the effect of smoothing the developer pumping failure (pitch unevenness) by the conveying and stirring means by the restricting member and the developer agitating at the restricting portion becomes strong, and the development pitch unevenness image does not occur and the image is highly reliable. It becomes a forming device. Further, in addition to such effects, the maintainability is improved. For example, even when the photoconductor or the developing device is out of order or has reached the end of its life, the entire state can be easily restored by replacing the entire cartridge with a new one, for example. be able to.

Next, a modification of the above embodiment will be described.
FIG. 9 is a diagram illustrating a configuration of the first transport screw 43Y and the second transport screw 44Y in a modification of the embodiment.
In FIG. 9, the central part of the rotation shaft of the first conveying screw 43Y is a large diameter part 431Y that is thicker than the shaft diameter of the small diameter part 432Y at both ends.
According to this embodiment, since the shaft diameter of the central portion of the rotation shaft of the first conveying screw 43Y is made thicker than the shaft diameters of both end portions, the weakest longitudinal center portion of the screw shaft is reinforced, thereby Is eliminated, the run-out is improved, and the adverse effect on developer pumping is reduced. In addition, by providing the developer layer thickness regulating member 50Y, the developer passes through the closest portion 50aY and the pressure in the vicinity thereof increases, but the central portion in the longitudinal direction of the first conveying screw 43Y is bent. Therefore, the unevenness of the surface of the agent can be suppressed.

Next, another modification of the present invention will be described.
FIG. 10 is a diagram showing the configuration of the first transport screw 43Y and the second transport screw 44Y in another modification.
In FIG. 10, the first conveying screw 43Y is provided with a tapered portion 433Y having a shaft diameter that sequentially changes between a large-diameter portion 431Y at the center and a small-diameter portion 432Y at both ends.
According to this embodiment, since there is no step portion between the thick shaft portion and the thin portion of the first conveying screw 43Y, the flow of the developer that tends to stagnate at the step portion becomes smooth, and the effect of suppressing the occurrence of abnormal images is achieved. Will be improved.

Next, an embodiment of an image forming method using the image forming apparatus provided with the developing device according to the present invention will be described.
The image forming method according to the present embodiment is an image forming method using, for example, the developing device or the process cartridge according to the present invention, and includes two-component development including toner and magnetic particles as a developer. Use the agent. At this time, the particle size of the magnetic particles (carrier particles) is smaller than the conventional one, and is 20 μm or more and 50 μm or less.
By reducing the particle size of the carrier particles, it is possible to form an image with more excellent dot reproducibility. Further, the thickness of the developer spike (carrier chain) at the time of image formation can be uniformly reduced, and more precise toner can be delivered. Further, since the density of developer spikes per unit area on the developing roller (developing sleeve) is increased, toner can be delivered to the latent image on the photoreceptor without a gap. As a result, it is possible not only to form an image with more excellent dot reproducibility but also to reduce development unevenness.
When the carrier particle diameter is larger than 50 μm, the total surface area of the carrier is reduced and the toner holding amount is reduced when compared with the same carrier amount. For this reason, the toner density is likely to decrease. In this case, it is possible to maintain the developing ability by increasing the pumping amount, but there is a problem that toner sticking easily occurs. On the other hand, if the carrier particle size is smaller than 20 μm, the magnetic force holding force by the mag roller is reduced, causing carrier scattering and increasing carrier adhesion to the photoreceptor. Note that dot reproducibility becomes high, and if the image quality becomes high, reproducibility such as development unevenness may be high.

The magnetic particles are, for example, magnetic particles in which a core material of a magnetic material is coated with a resin coat film, and the resin coat film contains a resin component obtained by crosslinking a thermoplastic resin and a melanin resin, and a charge control agent. It is preferable that
Specifically, it is preferable to use as the magnetic particles a coating film having elasticity and strong adhesive force, and coated with a coating film containing particles having a diameter larger than the film thickness on the surface.
FIG. 11 is a cross-sectional view showing an example of magnetic particles (hereinafter also referred to as carriers) applied in the present embodiment. In FIG. 11, ferrite 501 is applied as a core material of the carrier 500. The surface of the ferrite 501 is covered with a coat film 502 containing a charge adjusting agent in a resin component obtained by crosslinking a thermoplastic resin such as acrylic and a melamine resin. The coat film 502 has elasticity and strong adhesive force. For example, particles having a diameter larger than the film thickness of the coat film 502, for example, alumina particles 503 are dispersed on the surface of the coat film 502. The alumina particles 503 are held with a strong adhesive force of the coating film 502.
By applying such magnetic particles, it is possible to achieve stabilization of the developer pumping amount, that is, stabilization of image quality, over a long period of time.
That is, the conventional carrier is configured based on the idea of obtaining a long life while gradually scraping off the hard coat film, whereas the carrier 500 of the present embodiment has an impact due to the elasticity of the coat film 502. It is possible to suppress film scraping. Further, for example, by dispersing alumina particles 503 having a diameter larger than the film thickness on the surface of the carrier 501, the impact on the coating film 502 can be prevented and the spent material can be cleaned. As described above, since the coating film can be prevented from being scraped and spent, it is possible to achieve a longer life than conventional carriers. In addition, this makes it possible to expect the developer pumping amount to be stabilized, that is, to stabilize the quality over a long period of time. In addition, by extending the service life, not only the user maintenance is reduced, but also the manufacturing manufacturer is meaningful in terms of cost.

The toner applied to the exemplary embodiment is obtained by crosslinking a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent in an aqueous medium. And / or a toner obtained by an extension reaction.
Hereinafter, the constituent material and the manufacturing method of the toner will be described.
(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound.
Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO), and DIO alone or a mixture of DIO and a small amount of TO is preferable. Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. The trihydric or higher polyhydric alcohol (TO) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.
Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC), and DIC alone or a mixture of DIC and a small amount of TC is preferable. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1.
The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, it tends to be negatively charged, and furthermore, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.
The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.
In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.

Examples of the polyvalent isocyanate compound (PIC) 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.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.
The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.
The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, 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 wt%, the low-temperature fixability deteriorates.

The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.
Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.

The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 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 is lowered, and the hot offset resistance is deteriorated.
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 is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.
When reacting PIC and when reacting (A) and (B), a solvent may 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 isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran).
In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).

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 or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated.
By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.
The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.
The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.
The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient.
In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

(Coloring agent)
As the colorant, 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 iron oxide, 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, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min 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, Toluidine 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, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine, bitumen, anthraquinone blue, fast violet B, methyl violet, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalo Cyanine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner.
The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
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 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSY VP2038, 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) Manufactured), copper phthalocyanine, perylene, quinacridone, azo series Fee, a sulfonic acid group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.
The amount of charge control agent used is determined 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 not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the 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 charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, and rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 −3 to 2 μm, and particularly preferably 5 × 10 −3 to 0.5 μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m <2> / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 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. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle diameter of 5 × 10-2 μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed, a fluidity-imparting agent is not detached from the toner, a good image quality that does not cause fireflies and the like is obtained, and the residual toner is further reduced. .
Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large. However, when the added amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if
Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.

(Toner production method)
1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, 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 an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included.
The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 20000 parts by weight, it is not economical.
Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, polyhydric alcohol Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like.
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- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, 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 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).
Moreover, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a right fluoroalkyl group is used. Salt, benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries) Smoke), Megafac F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footage F-300 (Neos), and the like.

The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.).
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.
As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, 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 acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.
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. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group.
This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.
5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner.
The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like.
Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.
When the above method is used, a shape close to a sphere can be obtained as compared with the pulverized toner. Therefore, the granularity is improved, and a high-quality image without roughness can be obtained. Further, it is easy to reduce the particle size, and it is effective for higher image quality. On the other hand, since unevenness is also manifested, by combining with the present invention, a developing device with high image quality and less density unevenness can be provided.

The toner has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of volume average particle diameter (Dv) to number average particle diameter (Dn) of 1 in order to reproduce minute dots of 600 dpi or more. It is preferably in the range of .00 to 1.40.
The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do. Therefore, an image with high image quality and little density unevenness can be formed.

The toner preferably has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.
12 and 13 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2, respectively.
In FIG. 12, the shape factor SF-1 indicates the ratio of the roundness of the toner shape, and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) 2 / AREA} × (100π / 4) Formula (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.
In FIG. 13, the shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-2 = {(PERI) 2 / AREA} × (100π / 4) Expression (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.
Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.
When the shape of the toner is close to a sphere, the contact state between the toner and the toner or the toner and the photoconductor becomes point contact, so that the adsorbing force between the toners is weakened and the fluidity is increased, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable. A high transfer rate means that the developed toner image is faithfully reproduced.
This means that if the development toner image has development unevenness, it is faithfully reproduced without blurring after the transfer. For this reason, there is a possibility that development unevenness may become apparent, and by applying the present invention, an image with high image quality and little development unevenness can be formed.

The toner has a substantially spherical shape, and the shape is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), and the major axis r1 and minor axis r2. The ratio (r2 / r1) is preferably in the range of 0.5 to 1.0, and the ratio (r3 / r2) of the thickness r3 to the minor axis r2 is preferably in the range of 0.7 to 1.0. .
The toner applied to the present invention has a substantially spherical shape, and can be represented by the following shape rule.
FIG. 14A is a diagram schematically showing the shape of the toner applied to this embodiment.
In FIG. 14A, when a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner has a major axis and a minor axis. Ratio (r2 / r1) (see FIG. 14B) is 0.5 to 1.0, and the ratio of thickness to short axis (r3 / r2) (see FIG. 14C) is 0.7. It is preferable that it exists in the range of -1.0. When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved.
In addition, r1, r2, r3 can be measured by the following method, for example. That is, the toner is uniformly dispersed and adhered onto a smooth measurement surface, and 100 particles of the toner are magnified 500 times by a color laser microscope “VK-8500” (manufactured by Keyence Corporation) to obtain the 100 toners. The major axis r1 (μm), the minor axis r2 (μm), and the thickness r3 (μm) of the particles can be measured and obtained from their arithmetic average values.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is explanatory drawing which shows the image development apparatus part of FIG. It is explanatory drawing which shows the image development apparatus which is the characterizing part of this invention. It is explanatory drawing which shows the problem of a prior art. It is explanatory drawing which shows the effect in embodiment of this invention. It is a figure which shows the principal part of the image development apparatus of this invention. It is explanatory drawing which shows the principal part of the conventional developing device. It is a figure which shows schematic structure of a process cartridge. It is a figure which shows the modification of this invention. It is a figure which shows another modification of this invention. It is sectional drawing of the magnetic particle applied to this invention. FIG. 4 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-2. FIG. 3 is a diagram schematically illustrating the shape of a toner applied to an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Toner image formation part 2 Optical writing unit 3 Paper feed cassette 4 Paper feed cassette 5 Registration roller pair 6 Transfer unit 7 Fixing unit 8 Paper discharge tray 11 Photosensitive body (drum)
40 Developing Device 42 Developing Roller 43 First Conveying Screw 431 Large Diameter Portion 432 Small Diameter Portion 433 Tapered Portion 44 Second Conveying Screw 45 Regulating Blade 46 Toner Concentration Sensor 47 Partition Wall 49 Two-Component Developer 50 Layer Thickness Restricting Member 50a Nearest Portion 60 Transfer conveyance belt 100 Transfer paper 105 Charging means 106 Developing means 107 Photoconductor 108 Cleaning means 500 Carrier 501 Ferrite 502 Coat film 503 Alumina particles

Claims (12)

A partition wall that divides the developer accommodating portion that accommodates the developer into two to form a first supply portion and a second supply portion, a first agitation means provided in the first supply portion, and an interior of the second supply portion And a second agitator provided in the first supply unit, and disposed adjacent to and above the first agitator of the first supply unit, and supplies the developer conveyed by the first and second agitators to the photoreceptor. A developer carrying member that develops the electrostatic latent image on the photosensitive member, and a regulating blade that is disposed above the developer carrying member and regulates the layer thickness of the developer carried on the developer carrying member. In the developing device,
The partition wall is attached with a layer thickness regulating member that contacts the developer moving along the developer carrier on the upper side of the first stirring means, and regulates the layer thickness of the developer in the first supply unit,
2. A developing device according to claim 1, wherein a cross-sectional area of the screw blades of the first stirring means is larger than a cross-sectional area of the screw blades of the second stirring means. The developing device according to claim 1, wherein a shaft diameter of a central portion of the rotation shaft of the first stirring unit is larger than shaft diameters of both end portions. The taper part from which a shaft diameter changes one by one is provided between the center part with a large shaft diameter of the rotating shaft of the said 1st stirring means, and the both ends with a thin shaft diameter, It is characterized by the above-mentioned. Development device. An image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, a developer carried on the developer carrier, and transported to a development area facing the image carrier, and the image carrier An image having a developing device that develops a toner image by developing the electrostatic latent image on the upper surface, and a cleaning device that removes transfer residual toner remaining on the image carrier after the developed toner image is transferred to a transfer material. In a process cartridge applied to a forming apparatus, wherein the image carrier and at least the developing device are integrated, and the image forming apparatus main body is detachably formed.
The process cartridge according to claim 1, wherein the developing device is the developing device according to claim 1. An image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, a developer carried on the developer carrier, and transported to a development area facing the image carrier, and the image carrier An image having a developing device that develops a toner image by developing the electrostatic latent image on the upper surface, and a cleaning device that removes transfer residual toner remaining on the image carrier after the developed toner image is transferred to a transfer material. In the forming device,
5. The image forming apparatus according to claim 1, wherein the developing device is a developing device according to any one of claims 1 to 3 or a developing device for forming a process cartridge according to claim 4. An image forming method using the developing device according to any one of claims 1 to 3 or the image forming device including the process cartridge according to claim 4, or an image forming method using the image forming device according to claim 5.
An image forming method comprising using a two-component developer containing toner and magnetic particles as the developer.   The image forming method according to claim 6, wherein the magnetic particles have a particle size of 20 to 50 μm. The magnetic particles are obtained by coating a core material made of a magnetic material with a resin coating film containing a resin component obtained by crosslinking a thermoplastic resin and a melanin resin and a charge control agent. 8. The image forming method according to 7. In the toner, a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent is crosslinked and / or extended in an aqueous medium. The image forming method according to claim 6, wherein the toner is a toner obtained by applying the toner. The toner has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40. The image forming method according to claim 9. 11. The image forming method according to claim 9, wherein the toner has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. The toner has a substantially spherical shape, and the shape is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), and a ratio between the major axis r1 and the minor axis r2. (R2 / r1) is in the range of 0.5 to 1.0, and the ratio (r3 / r2) of the thickness r3 to the minor axis r2 is in the range of 0.7 to 1.0. The image forming method according to claim 9.

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