JP2008090185A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device which exhibits stable cleaning capability even in a high-temperature state and an image forming apparatus which has such a cleaning device and performs excellent image formation. <P>SOLUTION: The cleaning device includes a plate type member 332 which removes toner from a surface of a cleaned body 10, moving having the toner stuck on the surface, by bringing its end into contact with the surface of the cleaned body 10; a toner storage unit S where the toner removed by the plate type member moves to temporarily be stored; stagnation members 3341 and 3342 which are opposed to the cleaned body across the contact place where the plate type member contacts the cleaned body and making the toner removed from the surface of the cleaned body to move toward the toner storage unit temporarily stay at the contact place; a temperature detector 334 which detects the temperature of the toner staying at the contact place; and a releasing unit 3342 which temporarily releases the toner staying at the contact place when the detection result of the temperature detector indicates a predetermined high-temperature state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a cleaning device that removes toner on a member to be cleaned, and an image forming device that forms an image on a recording medium.

  2. Description of the Related Art Conventionally, image forming apparatuses such as printers and copiers have been widely used, and technologies relating to various elements constituting such image forming apparatuses have also been widely used. Among image forming apparatuses that employ an electrophotographic method, a pattern to be printed is formed on a photosensitive member by forming an electrostatic latent image having a different potential from the surrounding potential. In many cases, the electrostatic latent image formed in this way is developed with toner, and finally transferred onto a recording medium. Residual toner or paper powder remaining without being transferred may adhere to the surface of the photoconductor after transfer. In an electrophotographic image forming apparatus, such residual toner is prepared for the next image forming process. In many cases, a cleaning device for removing toner and the like is provided. Various cleaning methods are known, but among the cleaning methods, a blade cleaning method in which a rubber plate-like member called a cleaning blade is pressed against a photoconductor to scrape off residual toner (for example, patent documents) 1) has a desirable property because the cleaning mechanism is simple and thus the cost and size of the cleaning device can be reduced.

In the blade cleaning method, since the cleaning blade is always in pressure contact with the photoconductor, the friction between the cleaning blade and the photoconductor is large. This friction is alleviated to some extent by the residual toner functioning as a lubricant, but when forming an image with low residual toner, such as when forming an image with low density for a long time, the friction between the cleaning blade and the photosensitive member Friction may cause chipping of the cleaning blade and further wear of the photoreceptor surface. Therefore, a storage portion (toner reservoir) for storing the residual toner removed by the cleaning blade is provided in the vicinity of the tip of the cleaning blade that is in contact with the photosensitive member, and the residual toner collected is used as a lubricant by using the residual toner stored as a lubricant. There has been proposed a device for reducing friction with the photosensitive member even when forming a small number of images (for example, see Patent Document 2).
JP 2003-241607 A JP 11-161125 A

  In an image forming apparatus that employs an electrophotographic system, the number of image formation increases, and the temperature inside the image forming apparatus, particularly the temperature around the photoreceptor increases. The cleaning blade is often made of rubber, and its resilience decreases at high temperatures, and friction between the cleaning blade and the photosensitive member tends to increase. For this reason, the role played by the residual toner as a lubricant becomes particularly important at high temperatures. However, since the toner has a property that the fluidity is deteriorated in a high temperature state, the residual toner stored in the toner reservoir described in Patent Document 2 may not function as a lubricant in a high temperature state. Further, if the residual toner whose fluidity has deteriorated is stored as it is, the stored residual toner is fixed, which becomes an obstacle when the cleaning blade removes the residual toner from the photosensitive member. For this reason, in an image forming apparatus provided with a toner reservoir, image quality deterioration is likely to occur due to a decrease in cleaning properties at high temperatures.

  Recently, an increasing number of image forming apparatuses have reduced power consumption and heating time required for fixing processing by using toner that melts and fixes on a recording medium at a low temperature. Toner tends to cause the above-mentioned problems at a relatively low temperature, and the problem of image quality deterioration due to a decrease in cleaning properties becomes particularly serious.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a cleaning device that exhibits stable cleaning ability even in a high temperature state, and an image forming device that has such a cleaning device and performs good image formation. .

In order to achieve the above object, the cleaning device of the present invention comprises:
A plate-like member that removes the toner from the surface by contacting the end of the surface of the object to be cleaned that the toner adheres to the surface;
A toner storage unit in which the toner removed by the plate-like member moves and is temporarily stored;
The toner that is removed from the surface of the object to be cleaned and is opposed to the object to be cleaned across the contact point where the plate-shaped member is in contact with the object to be cleaned is the contact point. A stagnant member that temporarily stagnates,
A temperature detector for detecting the temperature of the toner stagnating at the contact point;
And an opening portion that at least temporarily releases the toner stagnating at the contact portion when the detection result of the temperature detection portion is in a predetermined high temperature state.

  Here, the “predetermined high temperature state” means that the temperature of the toner is such as a state where the temperature exceeds a predetermined threshold temperature or a state where the temperature exceeds a predetermined threshold temperature for a predetermined time or longer. It means a high state.

  In the cleaning device of the present invention, in a high temperature state, the toner stagnating at the contact portion is released and the toner is replaced. As a result, the adhesion of the toner whose fluidity has deteriorated at high temperatures is avoided, and the friction between the member to be cleaned and the plate-like member increases due to the toner having a reduced function as a lubricant. Is prevented. For this reason, the cleaning property is maintained even in a high temperature state.

In the cleaning device of the present invention, “the stagnant member has an openable / closable discharge port for discharging stagnant toner to the toner storing portion, and the open portion is the discharge port of the stagnant member. A mode in which the toner stagnating at the abutting position is opened by opening the opening is a preferable mode.

  According to such a form, the stagnant toner is easily released.

  In the cleaning device of the present invention, “the open portion is stagnant at the contact point in a high temperature state in which the temperature of the stagnant toner has reached a predetermined threshold temperature that is 10 ° C. lower than the glass transition temperature of the toner. The form of “releasing the toner being used” is also a preferable form.

  In the case of simple determination control of whether or not the temperature of the toner has reached a predetermined threshold temperature, if the threshold temperature is too high, the fluidity of the toner deteriorates rapidly, and the recovery of the deteriorated toner is not in time. However, if the threshold temperature is 10 ° C. or more lower than the glass transition temperature of the toner, the toner is appropriately discharged even with simple judgment control. For this reason, it is avoided that the toner having deteriorated fluidity is fixed, and the friction between the member to be cleaned and the plate-like member is increased due to the toner having a reduced function as a lubricant. Is prevented.

Further, in the cleaning device of the present invention, “the toner has a loss elastic modulus at 40 ° C. within a range of 2 × 10 ⁸ Pa or more and 7 × 10 ⁸ Pa or less” is a preferable embodiment. is there.

  In general, if the loss elastic modulus of the toner is too small, the toner is liable to be crushed and difficult to be removed, and the cleaning property is lowered and toner filming is likely to occur. On the other hand, if the loss elastic modulus of the toner is too large, the toner is not easily crushed, so the function as a lubricant between the object to be cleaned and the plate member is low, and the object to be cleaned is worn or damaged. Will go on.

Therefore, by adopting a toner whose loss elastic modulus at 40 ° C. falls within the range of 2 × 10 ⁸ [Pa] or more and 7 × 10 ⁸ [Pa] or less, high cleaning performance is exhibited and The burden on the cleaning body and the plate-like member is also reduced.

  Further, in the cleaning device of the present invention, “the toner is 16 in the population when the particles are ranked from the smallest particle size in the population in which the toner particles gather. A form in which the ratio of the particle size of the 50% order particle in the population to the particle size of the% order particle is 1.25 or less is a preferred mode.

  The above ratio is an amount representing the proportion of toner particles having a small particle diameter in the whole toner particles, and the smaller this ratio, the smaller the number of toner particles having a small particle diameter.

  In general, toner particles having a small particle size are likely to slip through the plate-like member, and the toner having a large number of toner particles having a small particle size has a lower cleaning property.

  In the cleaning apparatus of the present invention, a toner having a relatively small proportion of toner having a small particle diameter, which has the above ratio of 1.25 or less, is employed, and thus high cleaning performance is exhibited.

In order to achieve the above object, an image forming apparatus of the present invention comprises:
Rotating image carrier;
An image forming unit for forming a toner image on the image carrier;
A transfer fixing unit that transfers the image from the image carrier and fixes it on a recording medium; and a plate-like member that contacts the surface of the image carrier and removes the toner from the surface;
A toner storage unit in which the toner removed by the plate-like member moves and is stored at least temporarily;
The toner that has been removed from the surface of the image holding body and opposed to the image holding body across the contact portion where the plate-like member has contacted the image holding body, is directed to the toner storage portion. A stagnant member that temporarily stagnates,
A temperature detector for detecting the temperature of the toner stagnating at the contact point;
And a cleaning device having an open portion that at least temporarily opens the toner stagnating at the contact portion when the detection result by the temperature detection portion indicates a predetermined high temperature state. And

  Since the image forming apparatus of the present invention includes the above-described cleaning device, stable cleaning ability is exhibited even in a high temperature state, and good image formation can be performed.

  According to the present invention, stable cleaning ability is exhibited even in a high temperature state, and good image formation can be performed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a full-color image forming apparatus corresponding to an embodiment of the image forming apparatus of the present invention.

  An image forming apparatus 1 shown in FIG. 1 includes a photoreceptor 10 and an intermediate transfer belt 2. The photoconductor 10 is a laminated photoconductor for electrophotography, and rotates in the direction of arrow A in the figure at the time of image formation. The intermediate transfer belt 2 is an endless belt member stretched around support rolls 60a, 60b, 60c, and 60d, and circulates and moves in the direction of arrow B in the figure following the photoreceptor 10 during image formation. The intermediate transfer belt 2 includes an elastic belt base material and a protective layer that covers the surface of the belt base material and contains a conductive agent. Further, a primary transfer roll 40a is disposed at a position facing the photoconductor 10 with the intermediate transfer belt 2 interposed therebetween, and a secondary transfer roll 40b is further provided below (lower side in the figure). ing. Bias voltages are applied to the primary transfer roll 40a and the secondary transfer roll 40b from the primary transfer bias voltage application unit 41a and the secondary transfer bias voltage application unit 41b, respectively, at the time of image formation.

  Around the photosensitive member 10, a developing rotary 50, a charger 20, an exposure device 32, and a cleaning device 33 are disposed. The charger 20 is a contact type charger that charges the photoconductor while being in contact with the photoconductor 10. In the developing rotary 50, developing devices 51 to 54 containing developers each having colored toners of black (BK), yellow (Y), magenta (M) and cyan (C) are arranged along the circumferential direction. The developing device that performs development in the vicinity of the photosensitive member 10 can be switched by the rotation of the developing rotary 50. Each colored toner has a charging characteristic of charging the negative electrode, and each colored toner is added with external additive particles smaller than toner particles such as a lubricant, a transfer aid, and a cleaning aid. The exposure device 32 is responsible for irradiating the surface 10b of the photoreceptor 10 with laser light, and the cleaning device 33 is responsible for removing the toner remaining on the photoreceptor 10.

  In addition, the image forming apparatus 1 includes a roll brush 81 that is engaged in cleaning the intermediate transfer belt 2. The roll brush 81 can move in the direction of the double arrow C in the figure and can be switched between contact and separation with the intermediate transfer belt 2. When the intermediate transfer belt 2 is cleaned, the conductive bristles (brushes) of the roll brush 81 can be used. Fiber) 811 contacts the intermediate transfer belt 2. At the time of cleaning the intermediate transfer belt 2, the potential of the bristles 811 of the belt roll brush 81 becomes higher than the potential of the intermediate transfer belt 2 due to the voltage application from the toner charging voltage application unit 82, and the bristles 811 have the potential of the intermediate transfer belt 2. When the toner remaining on 2 contacts, the polarity of the toner is made positive. Control of contact or separation of the roll brush 81 is performed by the CPU 4, and the CPU 4 controls each part of the image forming apparatus such as the primary transfer bias voltage application unit 41 a and the secondary transfer bias voltage application unit 41 b described above. Also controls.

  Next, an image forming operation in the image forming apparatus 1 will be described.

  The image forming apparatus 1 forms an image by receiving input of image information representing one or more images having image signals of four colors of yellow, magenta, cyan, and black. When these image signals are input, the photoconductor 10 starts to rotate, and the charger 20 uniformly charges the surface of the rotating photoconductor 10. Of the input four-color image signals, first, laser light corresponding to the cyan image signal is emitted from the exposure device 32 toward the photoconductor 10, and this irradiation causes a potential around the surface of the photoconductor 10. An electrostatic latent image having a higher potential is formed. Further, by the rotation of the developing rotary 50, the developing device 54 containing cyan toner approaches the photoconductor 10, and the electrostatic latent image is developed with a developer containing cyan toner. When developing the electrostatic latent image, the developing device 54 containing cyan toner is applied with a bias voltage by a developing bias applying unit (not shown), and the potential is higher than the potential of the electrostatic latent image. The potential is low and higher than the potential of the photoconductor 10. For this reason, the cyan toner in the developing device 54 adheres to the electrostatic latent image after leaving the developing device 54 due to a potential difference between the electrostatic latent image and the developing device 54 containing cyan toner. A cyan toner image is formed. Here, this cyan toner image corresponds to an example of the developed image referred to in the present invention. In addition, as described below, magenta, yellow, and black toner images are also formed on the photoreceptor 10, and each of these color toner images corresponds to an example of the developed image referred to in the present invention. .

  Next, the formed cyan toner image is primarily transferred from the photoreceptor 10 to the intermediate transfer belt 2 by the primary transfer roll 40a. At the time of the primary transfer, the primary transfer bias is applied to the primary transfer roll 40a so that the potential of the primary transfer roll 40a is higher than the potential on the photoreceptor 10 where the cyan toner image is located. The primary transfer is realized by the voltage application unit 41a applying a positive bias voltage.

  Residual toner remaining without being primarily transferred is present on the photoconductor 10. This residual toner is removed from the photoconductor 10 by a polyurethane cleaning blade 332 provided in the cleaning device 33. The The cleaning blade 332 corresponds to an example of a plate-like member referred to in the present invention. The cleaning device 33 is also provided with a housing 331 surrounding the periphery of the cleaning blade 332, and residual toner removed by the cleaning blade 332 is accommodated in the housing 331. The housing 331 corresponds to an example of a toner storage unit according to the present invention.

  After the residual toner is removed by the cleaning device 33, the surface of the photoconductor 10 is again uniformly charged by the charger 20, and this time, the developing unit 53 containing magenta toner is rotated by the rotation of the developing rotary 50. Is close to the photoreceptor 10 and a magenta toner image is formed in the same manner as the cyan toner image described above. This magenta toner image is formed when the cyan toner image on the intermediate transfer belt 2 passes through the support rolls 60a, 60b, 60c, and 60d after the primary transfer and returns to the position of the primary transfer roll 40a. The timing is adjusted so that the formed magenta toner image is primarily transferred over the cyan toner image. After the magenta toner image is primarily transferred and superimposed on the cyan toner image, the yellow toner image and the black toner image are formed in the same manner and are superimposed on the magenta toner image and the cyan toner image. As a result, a multicolor toner image is formed on the intermediate transfer belt 2 by superimposing cyan, magenta, yellow, and black toner images.

  Subsequently, the multicolor toner image is secondarily transferred onto the sheet fed from the tray 6 by the paper feed roll 61 at a position sandwiched between the secondary transfer roll 40b and the support roll 60c. At the time of the secondary transfer, the secondary transfer roll 40b has a potential that is higher than the potential on the intermediate transfer belt 2 on which the multicolor toner image is positioned, with respect to the secondary transfer roll 40b. The secondary transfer is realized by the application of the bias voltage by the secondary transfer bias voltage application unit 41b.

The sheet that has undergone the secondary transfer of the multicolor toner image is subjected to heat and pressure by the fixing device 62 that is provided at a position separated in the right direction of the secondary transfer roll 40b in FIG. Fixing processing is performed. Generally, a toner having a smaller loss elastic modulus at 40 ° C. has a lower melting point, and the toner image is fixed at a lower temperature. In this image forming apparatus 1, in order to realize high fixability at a low temperature, the loss elastic modulus at 40 ° C. is 2 × 10 ⁸ [Pa] or more and 7 × 10 ⁸ [Pa] or less. Is adopted. By using the toner having such a low melting point, the image forming apparatus 1 achieves both reduction of power consumption during the fixing process and shortening of the heating time during the fixing process.

  When an image is formed on only one side of the sheet, the toner image is fixed by the fixing unit 62 and then discharged rightward as indicated by a right arrow in the figure. When image formation is performed on both sides of the sheet, the toner image is fixed on one side of the sheet in the fixing unit 62 and then returned without being discharged and passes between the pair of registration rollers 8 a near the fixing unit 62. It is conveyed in the left direction through a route indicated by a left-pointing arrow. Then, in the figure, the registration roll pair 8b shown on the left side of the secondary transfer roll 40b turns the transport direction to the right and goes again to the secondary transfer roll 40b. Here, during the period from when the sheet is first transferred by the secondary transfer roll 40b to when the sheet reaches the position of the secondary transfer roll 40b again, a new multi-color is formed on the intermediate transfer belt 2 by the method described above. A toner image is formed. Then, when the paper reaches the secondary transfer roll 40b for the second time, the new multicolor toner image is secondarily transferred to the surface opposite to that when the paper is subjected to the secondary transfer for the first time. The The paper after the second secondary transfer is subjected to a toner image fixing process by the fixing device 62 and discharged to the right.

  There is residual toner remaining on the intermediate transfer belt 2 without being subjected to secondary transfer. The residual toner is made positive by the roll brush 81 and is subjected to the above-described positive bias by the primary transfer bias voltage application unit 41a at the position of the primary transfer roll 40a. Move to 10. Then, it is removed from the photoreceptor 10 by the cleaning device 33.

  The above is the description of the image forming operation in the image forming apparatus 1.

  Next, the cleaning device 33 provided in the image forming apparatus 1 will be described. As described above, the cleaning device 33 employs a blade cleaning method using a cleaning blade.

  In general, in the blade cleaning method, since the cleaning blade is always in pressure contact with the photoconductor, the friction between the cleaning blade and the photoconductor is large. This friction is alleviated to some extent by the residual toner functioning as a lubricant, but when forming an image with low residual toner, such as when forming an image with low density for a long time, the friction between the cleaning blade and the photosensitive member Friction may cause damage to the surface of the photoreceptor, wear of the cleaning blade, or chipping.

  Therefore, in the cleaning device 33 of FIG. 1, a place (hereinafter referred to as a toner reservoir) for storing the residual toner removed by the cleaning blade 332 is provided near the tip of the cleaning blade 332 that contacts the photoreceptor 10. However, by using residual toner as a lubricant, it is devised to reduce friction with the photoreceptor even when an image is formed with little residual toner. Further, the cleaning device 33 is provided with a mechanism for discharging the accumulated residual toner from the toner reservoir according to the temperature of the residual toner.

  FIG. 2 is a view of a part of the cleaning device shown in FIG. 1 as viewed from one end side of the rotating shaft of the photosensitive member.

  Part (a) of FIG. 2 shows a state in which residual toner is stored in a toner reservoir provided on the lower side of the cleaning blade 332, and part (b) of FIG. The state when the residual toner is discharged from the toner reservoir is shown.

  A toner reservoir provided in the cleaning device 33 will be described with reference to part (a) of FIG. In part (a) of FIG. 2, the bottom portion of the housing 331 shown in FIG. 1 is shown in the lower part of the figure. A lower seal 333 is provided between the bottom portion of the housing 331 and the photoconductor 10. One end of the lower seal 333 is bonded to the housing 331, and the other end of the lower seal 333 is the photoconductor 10. It is in contact with the surface. Further, a fixed blocking member 3341 and a movable blocking member 3342 extending upward in the figure are provided at a distance from the surface of the photoconductor 10, and these fixed blocking member 3341 and the movable blocking member 3341 are movable. A space surrounded by the type blocking member 3342, the lower seal 333, and the photosensitive member 10 is a toner reservoir S in which residual toner removed by the cleaning blade 332 is stored. Here, a combination of the fixed blocking member 3341 and the movable blocking member 3342 corresponds to an example of a stagnation member according to the present invention. The residual toner removed by the cleaning blade 332 falls into the toner reservoir S, and gradually accumulates as the image forming operation proceeds. As shown in the figure, the tip of the cleaning blade 332 is buried in the residual toner. In such a state, the residual toner between the tip of the cleaning blade 332 and the photoconductor 10 acts as a lubricant, and the friction with the photoconductor is relieved even when an image is formed on the photoconductor 10 with little residual toner. When the residual toner accumulated in the toner reservoir S becomes full, the residual toner overflows from the upper side of the toner reservoir S and is carried by the transport auger 3313 to a toner storage location (not shown) provided in the housing 331. .

  In general, in an image forming apparatus adopting an electrophotographic system, the number of times of image formation increases, and the temperature inside the image forming apparatus, particularly the temperature around the photoreceptor increases, and may reach 40 ° C. or higher in some cases. is there. Since the rebound resilience of a rubber cleaning blade decreases at high temperatures, friction between the cleaning blade and the photosensitive member tends to increase. For this reason, the role played by the residual toner as a lubricant is important at high temperatures, but the toner has the property that the fluidity deteriorates when left in a high temperature for a long time. The residual toner stored in the toner may not function as a lubricant at a high temperature. Further, if the residual toner whose fluidity has deteriorated is stored as it is, it adheres to the stored location, which becomes an obstacle when the cleaning blade removes the residual toner from the photosensitive member. For this reason, simply providing a toner reservoir often reduces the cleaning performance at high temperatures. In particular, when a toner that melts at a low temperature is employed, the cleaning property is liable to deteriorate, and the above problem becomes particularly serious.

  Therefore, the image forming apparatus 1 in FIG. 1 has been devised to avoid such a problem of deterioration in cleaning performance at high temperatures.

  In the cleaning device 33 of FIG. 1, an infrared sensor 334 is provided above the toner reservoir S. The infrared sensor 334 indicates that the temperature of the residual toner accumulated in the toner reservoir S has reached a predetermined threshold temperature. When detected, the movable blocking member 3342 shown in part (a) of FIG. 1 rotates around the shaft 3342a in the X direction of the drawing to discharge the accumulated residual toner toward the left of the drawing.

  Part (b) of FIG. 2 shows a state in which the accumulated residual toner is discharged. When the movable blocking member 3342 falls to the left side of the part (b) in FIG. 2, the accumulated residual toner moves toward the inside of the housing 331 as indicated by the dotted arrow in the figure with the weight of the accumulated residual toner. Released. The movement of the movable blocking member 3342 is controlled by the CPU 4 shown in FIG. 1, and the CPU 4 detects that the temperature of the accumulated residual toner has reached a predetermined threshold temperature. Then, an instruction is given to a motor (not shown) in FIG. 2, and the movable blocking member 3342 is rotated. In the image forming apparatus 1 of FIG. 1, a temperature that is 10 ° C. or more lower than the glass transition temperature of the toner is set as the threshold temperature. Residual toner released toward the inside of the housing 331 is conveyed by a transport auger 3313 to a toner storage location (not shown) provided in the housing 331. The CPU 4 issues an instruction to a motor (not shown) again when the residual toner has been discharged for a predetermined time and the residual toner is near the tip of the cleaning blade 332, and the movable blocking member 3342 is moved to the arrow shown in the figure. The toner is returned to the Y direction, and accumulation of residual toner is started again.

  FIG. 3 is a view showing the movable blocking member shown in FIG. 2 in a plane along the axis.

  The movable blocking member 3343 is integrated with the shaft 3342a and rotates together with the shaft 3342a. A gear 1400b is provided at one end of the shaft 3342a, and the other end of the shaft 3342a is rotatably supported by a mechanism (not shown). The gear 1400b meshes with a gear 1400 that rotates by receiving the rotational driving force of the motor 1400a, and rotates in accordance with the rotation of the gear 1400. Here, a combination of the movable blocking member 3342, the shaft 3342a, the gear 1400b, the motor 1400a, and the gear 1400 corresponds to an example of the opening portion according to the present invention.

  Since the cleaning device 33 is provided with such a moving mechanism of the movable blocking member 3342, the residual toner is appropriately replaced, so that stable cleaning ability can be exhibited even if the temperature of the residual toner rises. it can.

  This completes the description of the mechanism that maintains good cleaning properties even at high temperatures. The image forming apparatus 1 is further devised for maintaining the cleaning property of the toner.

As described above, the loss elastic modulus at 40 ° C. of the low melting point toner employed in the image forming apparatus 1 belongs to a narrow range of 2 × 10 ⁸ [Pa] to 7 × 10 ⁸ [Pa]. ing.

  In general, if the loss elastic modulus of the toner is too small, the melting of the toner in the portion where the temperature on the paper is high proceeds more than in the other portions, resulting in deterioration of image quality such as uneven glossiness on the formed image. It is easy to happen. On the other hand, if the loss elastic modulus is too small, the toner is liable to be crushed and difficult to be removed, and the cleaning property is lowered and toner filming is likely to occur.

  On the other hand, if the loss elastic modulus of the toner is too large, the toner is not easily crushed this time, so that the function as a lubricant between the photoconductor and the cleaning blade is low, and wear of the photoconductor and damage to the cleaning blade proceed. .

Therefore, in this image forming apparatus 1, by adopting a toner whose loss elastic modulus at 40 ° C. is in the range of 2 × 10 ⁸ [Pa] or more and 7 × 10 ⁸ [Pa] or less, high cleaning performance is achieved. Is devised to reduce the burden on the photosensitive member and the cleaning blade.

  In addition, the toner employed in the image forming apparatus 1 has a uniform particle size, and is a toner that has a particularly small proportion of toner having an extremely small particle size. Statistical data that quantitatively represents that the proportion of toner having an extremely small particle size is small includes a lower value of a geometric standard deviation (hereinafter referred to as a lower GSD value) in the particle size distribution of the toner. Can be used). This lower GSD value is determined according to the following procedure.

  0.5 mg to 50 mg of toner as a measurement sample is dispersed in 2 ml of a 5% aqueous solution of sodium alkylbenzenesulfonate as a dispersant. In addition, as such a dispersant, a surfactant other than sodium alkylbenzene sulfonate can be used. Then, the dispersant in which the toner is dispersed is added to 100 [ml] of an electrolytic solution (ISOTON-II: manufactured by Beckman-Coulter), and dispersion treatment is performed for 1 minute using an ultrasonic disperser. After the dispersion treatment, the particle size distribution of toner particles of 2 μm to 60 μm is measured with a Coulter Multisizer II type (manufactured by Beckman-Coulter) using an aperture diameter of 100 μm. Here, a Coulter Multisizer II type (manufactured by Beckman Coulter, Inc.) is used as a measuring device, but other measuring devices may be used as long as the particle size distribution of toner particles can be measured.

  In the particle size distribution, the toner particles are ranked from the smallest particle size, and the particle size of the toner particles whose rank is 16% of the total number of particles is defined as D16p. Similarly, the particle diameter of toner particles whose rank is 50% of the total number of particles is defined as D50p. The lower GSD value is a value defined as the ratio (D50p / D16p) of these D16p and D50p.

  As is clear from the definition of the lower GSD value, the smaller the lower GSD value, the smaller the number of toner particles having a smaller particle size. The lower GSD value of the toner used in the image forming apparatus 1 is 1.25 or less, and the ratio of the toner having a small particle diameter is a considerably low toner. In the toner having a large lower GSD value, since the particle size is small, there are many toner particles that easily pass through the cleaning blade, and when such toner is employed, the cleaning property is deteriorated. The image forming apparatus 1 exhibits high cleaning performance by using toner having a lower GSD value of 1.25 or less.

  In the cleaning device 33 described above, a method is employed in which the accumulated toner remaining is released by turning the movable blocking member 3342 shown in FIG. 2. However, the movable blocking member is disposed on the lower side. It is also possible to employ a method in which the residual toner accumulated is released by retracting. In the following, a cleaning apparatus employing such a method will be introduced.

  FIG. 4 is a view of a part of a cleaning device that employs a method in which residual toner is discharged by retracting the movable blocking member downward, as viewed from one end of the rotating shaft of the photosensitive member.

  Part (a) of FIG. 4 shows a state in which residual toner is stored in a toner reservoir provided on the lower side of the cleaning blade 332, and part (b) of FIG. The state when the residual toner is discharged from the toner reservoir is shown.

  In FIG. 4, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and redundant description of the components will be omitted. As in the cleaning device 33 shown in FIG. 2, the cleaning device 33 ′ shown in FIG. 4 moves the movable blocking member to release the residual toner when the temperature of the accumulated residual toner reaches a predetermined threshold temperature. Done. The cleaning device 33 ′ shown in FIG. 4 is different from the cleaning device 33 shown in FIG. 2 in that the moving mechanism of the movable blocking member at this time is different. The following description will focus on this point.

  In the cleaning device 33 ′ shown in FIG. 4, a cam 3342 b ′ is provided below the movable blocking member 3342 ′, and this cam 3342 b ′ is in contact with one end of the movable blocking member 3342 ′. As the cam 3342b ′ rotates about the shaft 3342a ′, the movable blocking member 3342 ′ moves between the housing 331 ′ and the lower seal 333 in the vertical direction in the drawing to block the residual toner. A state and a state of discharging residual toner are realized. Specifically, when the residual toner is accumulated as shown in part (a) of FIG. 4, when the cam 3342b ′ rotates in the direction of arrow D in part (a) of FIG. 4, the movement of the cam 3342b ′. Accordingly, the movable blocking member 3342 ′ moves in the direction of arrow E in part (a) of FIG. In a state where the movable blocking member 3342 'is completely lowered, a state in which residual toner is released as shown in part (a) of FIG. 4 is realized. After the release of the residual toner, the cam 3342b ′ rotates in the direction of arrow F in part (b) of FIG. 4, and the movable blocking member 3342 ′ is now replaced with the movement of the cam 3342b ′. Moving in the direction of arrow G in (a), the accumulation of residual toner is started again. Except for the point that the moving mechanism of the movable blocking member is different, the configuration of the image forming apparatus provided with the cleaning device 33 'is the same as the configuration of the image forming apparatus shown in FIG.

  In the cleaning device 33 shown in FIG. 2 and the cleaning device 33 ′ shown in FIG. 4, the residual toner accumulated is released by the movement of the movable blocking member. A method in which the entire member to be closed is opened and closed to release residual toner may be employed. As such a method, for example, a method of realizing a state of blocking the residual toner or a state of discharging the residual toner by the entire member blocking the residual toner turning around the upper part is conceivable. In addition, in such a system, when a large amount of residual toner is accumulated, the residual toner is gradually released from the lower side of the member that blocks the residual toner so as to push the member off, and is released in a large amount in a high temperature state. It may be a thing.

Below, the manufacturing method of the toner employ | adopted with this image forming apparatus 1, and the manufacturing method of the two-component developer which has the toner are demonstrated. Here, as an example, a method for producing a toner having a loss elastic modulus at 40 ° C. of 4 × 10 ⁸ [Pa] and a lower GSD value of 1.24 will be described.
-Adjustment of crystalline resin-
In a three-necked flask, 100 parts by mass of dimethyl decanoate, 75.0 parts by mass of 1,9-nonanediol and 0.08 parts by mass of dibutyltin oxide are reacted at 180 ° C. for 8 hours in a nitrogen atmosphere. During the reaction, generated water was removed out of the system. Thereafter, while gradually reducing the pressure, the temperature was raised to 230 ° C. and the reaction was performed for 7 hours, followed by cooling to obtain a crystalline resin. The weight average molecular weight of this crystalline resin was 17000.
-Production of non-crystalline resin-
In a three-necked flask, 82 parts by mass of dimethyl terephthalate, 82 parts by mass of dimethyl isophthalate, 79 parts by mass of bisphenol A ethylene oxide adduct, 257 parts by mass of bisphenol A propylene oxide adduct, and 0.23 parts by mass of dibutyltin oxide were added in a nitrogen atmosphere. , Reacted at 180 ° C. for 3 hours. During the reaction, generated water was removed out of the system. Thereafter, while gradually reducing the pressure, the temperature was raised to 240 ° C. and reacted for 2 hours, followed by cooling to obtain an amorphous resin. The amorphous resin had a weight average molecular weight of 16,500.
-Preparation of crystalline / amorphous mixed resin dispersion-
To a three-necked flask, add 30 parts by mass of the above crystalline resin, 70 parts by mass of the above amorphous resin, 50 parts by mass of methyl ethyl ketone, and 15 parts by mass of isopropyl alcohol, and heat to 60 ° C. while stirring. Is dissolved, and 25 parts by mass of a 10% aqueous ammonia solution is added. Further, 400 parts by mass of ion-exchanged water is gradually added to carry out phase inversion emulsification, and after solvent removal, the solid content concentration is adjusted to 25% to obtain a crystalline / amorphous mixed resin dispersion. The volume average diameter of the resin fine particles in the dispersion was 158 nm.
-Preparation of release agent dispersion-
Paraffin wax (Nippon Seiwa Co., Ltd .: HNP9, melting point 77 ° C.): 60 parts by mass Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK): 4 parts by mass Ion exchange water: 200 Part by mass A solution in which the above components were mixed was heated to 120 ° C. and dispersed using a homogenizer (manufactured by IKA: Ultra Tarrax T50), then dispersed with a Menton Gorin high-pressure homogenizer (Gorin), and volume averaged. A release agent dispersion was prepared by dispersing a release agent having a particle size of 250 nm. The water content was adjusted so that the mold release agent concentration of this dispersion was 20% by mass.
-Preparation of colorant dispersion-
Cyan pigment (copper phthalocyanine B15: 3, manufactured by Dainichi Seika Co., Ltd.): 50 parts by mass Nonionic surfactant Nonipol 400 (manufactured by Kao Corporation): 5 parts by mass Ion exchange water: 200 parts by mass After mixing and dissolving, the mixture was dispersed for about 1 hour using a high-pressure impact disperser Ultimateizer (manufactured by Sugino Machine Co., Ltd., HJP30006), and the water content was adjusted to obtain a colorant particle dispersion (1).
-Manufacture of toner base particles-
-Crystalline / non-crystalline mixed resin dispersion: 720 parts by weight-Colorant dispersion: 50 parts by weight-Release agent dispersion: 70 parts by weight-Cationic surfactant-(Kao Corporation ) Product: Sanisol B50): 1.5 parts by mass The above components are contained in a round stainless steel flask, and 0.1 N sulfuric acid is added to adjust the pH to 3.8. 30 parts by mass of an aqueous nitric acid solution having an aluminum chloride concentration of 10% by weight was added.

  Then, after dispersing at 30 ° C. using a homogenizer (manufactured by IKA, Ultra Tarrax T50), the temperature rise per minute is controlled to be 0.5 ° C. in an oil bath for heating to 40 ° C. Until heated. The volume average particle diameter of the obtained core aggregated particles was measured to be 5.2 μm.

  After this aggregated particle dispersion was held at 40 ° C. for 30 minutes, 160 parts by mass of the amorphous resin dispersion was gently added to the dispersion in which the core aggregated particles were formed, and held for 1 hour. The obtained adhered resin agglomerated particles had a volume average particle size of 6.2 μm. After adjusting the pH to 7.0 by adding 0.1 N nitric acid, the mixture was heated to 95 ° C. with continuous stirring and held for 5 hours.

Thereafter, the mixture was cooled to 20 ° C. at a rate of 20 ° C./min, filtered, washed with ion-exchanged water, and then dried using a vacuum dryer to obtain toner base particles. The obtained toner base particles had a volume average particle size of 6.1 μm.
-Manufacture of carriers-
Ferrite (Cu—Zn) particles (volume average particle size: 50 μm): 100 parts by mass Toluene: 14 parts by mass Styrene-methyl methacrylate copolymer (component ratio: styrene / methyl methacrylate = 90/10, weight average molecular weight Mw = 80000): 2 parts by mass Carbon black (R330: manufactured by Cabot Corporation): 0.2 parts by mass First, the above components excluding ferrite particles were stirred with a stirrer for 10 minutes to prepare a dispersed coating solution. The coating liquid and ferrite particles were put in a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes, and then degassed and deaerated while being heated, and dried to obtain a carrier.
-Production of developer-
1.2 parts by mass of commercially available fumed silica RX50 (manufactured by Nippon Aerosil Co., Ltd.) as an external additive to 100 parts by mass of the toner is added to the toner base particles described above, and mixed with a Henschel mixer to obtain an electrostatic image developing toner. Obtained. Subsequently, 8 parts by mass of the toner and 100 parts by mass of the carrier were mixed to prepare a two-component developer.
(Volume average particle size)
When measuring the volume average particle diameter of the toner, Coulter Multisizer II type (manufactured by Beckman Coulter, Inc.) was used as described above, and the above-mentioned conditions were used. A cumulative distribution was drawn from the small diameter side on the volume basis with respect to the particle size range (channel) obtained by dividing the measured particle size distribution, and the particle size (D50v) at which accumulation was 50% was defined as the volume average particle size. From the above particle size distribution, the lower GSD value is determined according to the above-described definition.
(Loss elastic modulus)
The measurement was performed using a viscoelasticity measuring device (Rheometric Scientific FE: ARES). First, an electrostatic latent image developing toner was formed into a tablet, set on a parallel plate having a diameter of 8 mm, and the normal force was set to 0. Then, vibration was applied at a vibration frequency of 6.28 rad / sec. The measurement temperature was 30 ° C. to 500 ° C., and the strain at this time was 0.1%. The measurement time interval was 120 seconds, the temperature increase rate after the start of measurement was 1 ° C./min, and the loss elastic modulus at 40 ° C. was measured.
(Weight average molecular weight)
The molecular weight distribution of the crystalline resin or the like is performed under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)” apparatus, and two columns use “TSKgel, SuperHM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15 cm)”. , THF (tetrahydrofuran) was used as an eluent. As experimental conditions, an experiment was performed using a sample concentration of 0.5%, a flow rate of 0.6 ml / min, a sample injection amount of 10 μl, a measurement temperature of 40 ° C., and an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.
(Melting point of release agent, glass transition temperature)
The melting point and glass transition temperature were determined by a DSC (Differential Scanning Calorimeter) measurement method, and were determined from the main maximum peak measured according to ASTM D3418-8.

  DSC-7 manufactured by Perkin Elmer Co. can be used for measurement of the main maximum peak. The temperature correction of the detection part of this apparatus uses the melting point of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. As the sample, an aluminum pan was used, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

The above is the description of the method for producing the toner employed in the image forming apparatus 1 and the method for producing the two-component developer having the toner. In the production of the above toner, as an example, a method for producing a toner having a loss elastic modulus at 40 ° C. of 4 × 10 ⁸ [Pa] and a lower GSD value of 1.24 has been described. The lower GSD value can be changed by changing the processing in the toner manufacturing method. Specifically, regarding the loss elastic modulus of the toner, the loss at 40 ° C. is obtained by increasing (decreasing) the weight average molecular weight of the crystalline resin in the process of “adjustment of the crystalline resin” in the above toner production method. The elastic modulus can be increased (decreased). For the lower GSD value, the rate of temperature increase per minute when heating to 40 ° C. in an oil bath for heating in the process of “production of toner base particles” in the above toner production method is 0. The lower GSD value can be increased (decreased) by making it larger (smaller) than 5 ° C./min. This is because, generally, as the temperature rises more steeply, the degree of aggregation tends to vary depending on the aggregated particles, and as a result, the particle size of the aggregated particles becomes uneven.

In the following, as described with reference to FIG. 2, a mechanism for storing and discharging residual toner is provided, and toner having characteristics suitable for avoiding a deterioration in image quality is used. That specific image formation is performed is verified by specific experimental data.
[Experiment 1]
In this experiment, the optimum loss elastic modulus of toner for good image formation will be verified. In this experiment, a color double-sided image having a patch portion with a density of 100% was output at 10,000 sheets at a high temperature and high humidity of 28 ° C. and 85% of humidity, and further at a low temperature and low humidity of 10 ° C. and 15% of humidity. A continuous output test is performed to output 10,000 sheets. Further, after the continuous output test, a toner band having a surface density of 15 [g / m ² ] and a length of 300 mm is formed on the photosensitive member, and the photosensitive member is cleaned without primary transfer. An image output test after cleaning, in which a color double-sided image is output, is also performed.

The continuous output test and the image output test after cleaning are performed by the following image forming apparatus.
(Example 1)
Loss elasticity at 40 ° C. is obtained by changing 240 ° C. at the time of temperature rise to 220 ° C. in the process of “adjustment of crystalline resin” in the toner production method described above, and setting the weight average molecular weight of the crystalline resin to 11700. An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner whose rate is adjusted to 2 × 10 ⁸ [Pa] is employed.

In this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
(Example 2)
Loss elasticity at 40 ° C. is obtained by changing 240 ° C. at the time of temperature rise to 230 ° C. in the process of “adjustment of crystalline resin” in the toner production method described above, and setting the weight average molecular weight of the crystalline resin to 15000. An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner whose rate is adjusted to 3.3 × 10 ⁸ [Pa] is employed.

Also in this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
(Example 3)
In the process of “adjustment of crystalline resin” in the above-described toner production method, the temperature increase time is changed from 2 hours to 3 hours, and the weight average molecular weight of the crystalline resin is set to 18100, so that the temperature at 40 ° C. An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner having a loss elastic modulus adjusted to 4.8 × 10 ⁸ [Pa] is employed.

Also in this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
Example 4
In the process of “adjustment of the crystalline resin” in the toner production method described above, the temperature rise time is changed from 2 hours to 4 hours, and the weight average molecular weight of the crystalline resin is set to 20600, so that the temperature at 40 ° C. An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner having a loss elastic modulus adjusted to 6.3 × 10 ⁸ [Pa] is employed.

Also in this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
(Example 5)
In the process of “adjustment of the crystalline resin” in the above-described toner production method, the temperature increase time is changed from 2 hours to 5 hours, and the weight average molecular weight of the crystalline resin is set to 21700, so that the temperature at 40 ° C. An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner having a loss elastic modulus adjusted to 7.0 × 10 ⁸ [Pa] is employed.

Also in this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
(Example 6)
In the process of “adjusting the crystalline resin” in the toner production method described above, the temperature average temperature 240 ° C. is changed to 210 ° C., the time is changed from 2 hours to 2.5 hours, and the weight average molecular weight of the crystalline resin is 11600. The image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that the toner having a loss elastic modulus at 40 ° C. adjusted to 2 × 10 ⁸ [Pa] is used.

In this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 50 ° C. This is different from the image forming apparatus of the first embodiment.
(Example 7)
In the process of “adjusting the crystalline resin” in the toner production method described above, the temperature average temperature is changed from 240 ° C. to 200 ° C. and the time from 2 hours to 3 hours, so that the weight average molecular weight of the crystalline resin is 11700. Accordingly, the image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that the toner whose loss elastic modulus at 40 ° C. is adjusted to 2 × 10 ⁸ [Pa] is employed.

In this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 55 ° C. This is different from the image forming apparatus of the first embodiment.
(Example 8)
Loss elasticity at 40 ° C. is obtained by changing 240 ° C. at the time of temperature rise to 210 ° C. in the process of “adjustment of crystalline resin” in the toner production method described above, and setting the weight average molecular weight of the crystalline resin to 10500. An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner whose rate is adjusted to 1.6 × 10 ⁸ [Pa] is employed.

In this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
Example 9
In the process of “adjusting the crystalline resin” in the toner production method described above, the temperature is raised from 240 ° C. to 250 ° C., and the time is changed from 2 hours to 5 hours, so that the weight average molecular weight of the crystalline resin is 22,500. Thus, an image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that a toner having a loss elastic modulus at 40 ° C. adjusted to 7.5 × 10 ⁸ [Pa] is employed.

In this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
(Example 10)
In the process of “adjusting the crystalline resin” in the toner production method described above, the temperature average temperature is changed from 240 ° C. to 190 ° C. and the time from 2 hours to 4 hours, so that the weight average molecular weight of the crystalline resin is 11800. Thus, a toner whose loss modulus at 40 ° C. is adjusted to 2 × 10 ⁸ [Pa] is employed, and in the process of “manufacturing toner mother particles” in the above toner production method, 1 except that the lower GSD value was increased to 1.26 by increasing the rate of temperature increase per minute when heating to 40 ° C. at 0.5 ° C./min. 1 is an image forming apparatus having the same configuration as in FIG.

In this image forming apparatus, the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.
(Comparative Example 1)
An image forming apparatus having the same configuration as that of the image forming apparatus 1 shown in FIG. 1 except that the mechanism for moving the toner blocking member according to temperature is not provided.

The image forming apparatus of Comparative Example 1 is provided with a mechanism for storing toner, and the residual toner in the toner reservoir is discharged regardless of the temperature from a hole provided in the lower portion of the toner reservoir. In the image forming apparatus of Comparative Example 1, as in Example 1, the weight average molecular weight of the crystalline resin is 11700 and the loss elastic modulus is 2 in the process of “adjustment of crystalline resin” in the toner production method described above. The toner of Example 1 adjusted to × 10 ⁸ [Pa] is employed, and the threshold temperature for discharging the accumulated residual toner is set to 45 ° C.

  For each of the above Examples 1 to 10 and Comparative Example 1, the degree of wear of the photoconductor after the continuous output test, the degree of toner filming on the photoconductor after the continuous output, and the cleaning blade after the continuous output Check the extent of damage. For the image output test after cleaning, the cleaning performance is evaluated from the result of image quality.

The degree of wear of the photoreceptor is evaluated as follows. The maximum length of the scratches on the photoconductor after the continuous output test is examined, and the length is divided by the number of rotations of the photoconductor in the continuous output test to determine the length of the scratch per 1000 revolutions (1 [kcycle]). Find out how much. Depending on the length of scratches per 1000 revolutions (hereinafter referred to as the wear rate), the degree of wear of the photoconductor after the continuous output test is divided into the following categories for evaluation.
○: Wear rate is 2 [nm / kcycle] or more and less than 10 [nm / kcycle] Δ: Wear rate is 10 [nm / kcycle] or more and less than 50 [nm / kcycle] ×: Wear rate is less than 2 [nm / kcycle] Or the wear rate is 50 [nm /
cycle] In general, in the cleaning of the photoconductor, the surface of the photoconductor is scraped off, so that toner filming and the like that are difficult to be removed only by rubbing the surface of the photoconductor with the cleaning blade are also removed. For this reason, if the photoconductor is not very worn, toner filming may not be sufficiently removed. In the above evaluation method, if the wear rate is less than 2 [nm / kcycle], the surface property of the photoconductor is inappropriate. It is classified into the category of “×”.

Further, the degree of toner filming on the photoconductor after continuous output is evaluated according to the following categories.
○: No toner filming on the photoconductor and good image quality Δ: Toner filming is slightly seen on the photoconductor but has little effect on image quality ×: Toner filming is seen on the photoconductor The image quality is deteriorated. Further, the cleaning property after removing the toner band on the photosensitive member is evaluated as follows.
○: Image quality defects such as white lines and color lines do not exist in the output image. Δ: Image quality defects such as white lines and color lines do not exist in the output image, but color lines appear on the charger surface. Image quality defects such as white stripes and color stripes are observed in the image.The degree of damage to the cleaning blade after continuous output is divided into the following categories depending on the degree of chipping at the edge where the cleaning blade contacts the photoconductor: Separately evaluate.
○: There is no chip with a length of 15 μm or more. Δ: There is a chip with a length of 15 μm or more but less than 30 μm, but there is no chip with a length of 30 μm or more. X: There is a chip with a length of 30 μm or more. 1 shows the results of Examples 1 to 10 and Comparative Example 1.

  A comparison between Example 3 having a mechanism for moving the toner blocking member in accordance with temperature and Comparative Example 1 having no such moving mechanism shows that in Comparative Example 1, photoconductor wear and While the result of “x” was obtained in both items of blade damage, the result of “◯” was obtained in any item in Example 3. From this, it can be understood that the friction between the photosensitive member and the cleaning blade can be reduced at a high temperature by moving the toner blocking member to replace the residual toner in the toner pool at a high temperature. . As for the items of toner filming and cleaning properties, the result of “X” was obtained in both items in Comparative Example 1, whereas the result of “◯” was obtained in all items in Example 3. Is obtained. Thus, it can be seen that the cleaning performance is maintained even at high temperatures by providing a mechanism for moving the toner blocking member.

When the loss elastic modulus of the toner at 40 ° C. is compared among Examples 1 to 5, 5, and 9, the loss elastic modulus of the toner at 40 ° C. is 1. In Example 8, which is the smallest value of 6 × 10 ⁸ [Pa], the result of “x” was obtained for the toner filming and cleaning properties, whereas the toner loss at 40 ° C. In Examples 1 to 5 in which the elastic modulus is in the range of 2 × 10 ⁸ [Pa] to 7 × 10 ⁸ [Pa], a result of “◯” is obtained in any item. Further, in Example 9 in which the loss elastic modulus of the toner at 40 ° C. is the largest value of 9 × 10 ⁸ [Pa], the result of “x” in both items of photoconductor wear and blade damage. On the other hand, in Examples 1 to 5 where the loss elastic modulus of the toner at 40 ° C. is in the range of 2 × 10 ⁸ [Pa] to 7 × 10 ⁸ [Pa], The result of “○” is also obtained.

  In general, if the loss elastic modulus of the toner is too small, the melting of the toner in the portion where the temperature on the paper is high proceeds more than in the other portions, resulting in deterioration of image quality such as uneven glossiness on the formed image. It is easy to happen. On the other hand, if the loss elastic modulus is too small, the toner is liable to be crushed and difficult to be removed, and the cleaning property is lowered and toner filming is likely to occur.

  On the other hand, if the loss elastic modulus of the toner is too large, the toner is not easily crushed, so that the function as a lubricant between the photoconductor and the cleaning blade is low, and the photoconductor is worn and the cleaning blade is damaged.

The results in Table 1 reflect this, and as in Examples 1 to 5, the loss elastic modulus at 40 ° C. is in the range of 2 × 10 ⁸ [Pa] or more and 7 × 10 ⁸ [Pa] or less. It can be seen that by using the toner belonging to the above, high cleaning performance is exhibited and the burden on the photosensitive member and the cleaning blade is reduced.

  Further, when comparing the first, sixth, and seventh embodiments having different threshold temperatures, in the seventh embodiment in which the threshold temperature is 55 ° C., photoconductor wear, toner filming, and cleaning are performed. In each of the items of the property and the damage of the blade, the evaluation was “△”, whereas in the example 6 with the threshold temperature of 50 ° C., the cleaning property and the blade Regarding the item of damage, the evaluation is improved to “◯”, and in Example 1 in which the threshold temperature is 45 ° C., all items of photoconductor wear, toner filming, cleanability, and blade damage are “ The result is “O”.

Generally, the fluidity of the residual toner deteriorates as the function as a lubricant and the cleaning property decrease, when the temperature of the residual toner becomes too close to the glass transition point of the toner. The toner having a loss elastic modulus of 2 × 10 ⁸ [Pa] employed in Example 1, Example 6, and Example 7 has a glass transition temperature of 60 ° C., and the above Examples 1 and Example are used. From the results of Examples 6 and 7, in order to obtain an evaluation that at least “◯” is at least two acceptable levels as in Example 6, a temperature that is 10 ° C. or more lower than the glass transition temperature of the toner is set as a threshold value. It can be seen that it is desirable to set the temperature.

  Further, when Example 1 and Example 10 having different GSD values on the lower side are compared, in Example 10 with the lower GSD value of 1.26, “Δ” in toner filming and cleaning properties. On the other hand, in Example 1 where the lower GSD value is 1.24, a result of “◯” is obtained for all items. With toner having a high proportion of toner particles having a small particle diameter, residual toner tends to slip through the cleaning blade. For this reason, the cleaning property is deteriorated, and further toner filming occurs. The above result reflects this. If the lower GSD value is lower than or equal to 1.25, which is intermediate between the lower GSD value of the first embodiment and the lower GSD value of the tenth embodiment. Therefore, it is considered that good cleaning properties are realized.

To summarize the above considerations, it can be concluded that by providing the moving mechanism for the toner blocking member, the cleaning performance is maintained even at high temperatures and the friction between the photosensitive member and the cleaning blade is also reduced. The threshold temperature for moving the toner blocking member is set to a temperature that is 10 ° C. or more lower than the glass transition temperature of the toner, and the loss elastic modulus of the toner at 40 ° C. is 2 × 10 ⁸ [Pa] or more and 7 × 10 ^8. [Pa] By using a toner belonging to the following range and having a lower GSD value of 1.25 or more, higher cleaning performance is exhibited, and it is effective to avoid photoconductor wear and cleaning blade damage. I understand that.

  The image forming apparatus described above is a rotary type full color image forming apparatus. However, the image forming apparatus of the present invention may be applied to a tandem type full color image forming apparatus or a monochrome image forming apparatus.

  Further, as a material for the cleaning blade used in the present invention, urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, and butadiene rubber may be employed in addition to the above polyurethane.

1 is a diagram illustrating a schematic configuration of a full-color image forming apparatus corresponding to an embodiment of an image forming apparatus of the present invention. FIG. 2 is a view of a part of the cleaning device shown in FIG. 1 when viewed from one end side of a rotating shaft of a photoreceptor. FIG. 3 is a diagram illustrating the movable blocking member illustrated in FIG. 2 in a plane along an axis. FIG. 3 is a view of a part of a cleaning device that employs a method in which residual toner accumulated by discharging a movable blocking member downward is viewed from one end side of a rotating shaft of a photoreceptor.

Explanation of symbols

1 Image forming apparatus,
1400a ... motor,
1400b ... gear,
10: Photoconductor,
2 ... Intermediate transfer belt,
20: Charger,
32 ... exposure unit,
33, 33 '... cleaning device,
331: housing,
332 ... Cleaning blade,
333 ... bottom seal,
334 ... an infrared sensor,
3341 ... Fixed block member,
3342, 3342 '... fixed type blocking member,
3342a, 3342a '... axis,
3342b '... cam,
4 ... CPU,
40a ... primary transfer roll,
40b ... secondary transfer roll,
41a ... Primary transfer bias voltage application unit,
41b ... Secondary transfer bias voltage application unit,
50: Development rotary,
51, 52, 53, 54 ... developer,
60a, 60b, 60c, 60d ... support rolls,
6 ... Tray,
61: Paper feed roll,
62 ... Fixer,
81 ... roll brush,
811 ... hair,
82: Toner charging voltage application unit

Claims (2)

A plate-like member that removes the toner from the surface by contacting the end of the surface of the object to be cleaned that the toner adheres to the surface;
A toner storage unit in which the toner removed by the plate-like member moves and is temporarily stored;
The toner that is removed from the surface of the object to be cleaned and is opposed to the object to be cleaned across the contact part where the plate-like member is in contact with the object to be cleaned is the contact part. A stagnant member that temporarily stagnates,
A temperature detector for detecting the temperature of the toner stagnating at the contact point;
A cleaning device, comprising: an opening portion that at least temporarily releases toner stagnating at the contact portion when a detection result by the temperature detection portion is in a predetermined high temperature state. Rotating image carrier;
An image forming unit for forming a toner image on the image carrier;
A transfer fixing unit that transfers the image from the image carrier and fixes it on a recording medium; and a plate-like member that contacts the surface of the image carrier and removes the toner from the surface;
A toner storage unit in which the toner removed by the plate-like member moves and is temporarily stored;
The toner that has been removed from the surface of the image holding body and opposed to the image holding body across the contact portion where the plate-shaped member has contacted the image holding body, is moved to the toner storage portion. A stagnant member that temporarily stagnates,
A temperature detector for detecting the temperature of the toner stagnating at the contact point;
And a cleaning device having an opening that at least temporarily opens the toner stagnating at the contact portion when the detection result by the temperature detector is in a predetermined high temperature state. Forming equipment.

Images