JP2020052140A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that reduces the amount of emission of UFPs to the outside of the apparatus.SOLUTION: An image forming apparatus comprises: an image holding body; charging means; electrostatic charge image forming means; developing means that stores a developer containing a toner including toner particles containing a mold release agent having a melting temperature of 60°C or more and 100°C or less, and develops an electrostatic charge image formed on the image holding body with the developer to form a toner image; transfer means; fixing means that fixes the toner image on a surface of a recording medium, the fixing means having a first fixing unit that inserts the recording medium into a first contact area for heating and a second fixing unit that inserts the recording medium after the insertion into the first contact area into a second contact area for heating; and an air supply pipe that connects an air supply inlet provided around the upstream of the first contact area with an air supply outlet provided downstream of the second contact area and around a conveyance path of the recording medium, and exhausts air entering from the air supply inlet toward the recording medium from the air supply outlet.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus.

  In the formation of an image by electrophotography, for example, after charging the surface of an image carrier, an electrostatic image is formed on the surface of the image carrier in accordance with image information, and then the electrostatic image is developed using toner. The toner image is formed by developing with a developer, and the toner image is transferred and fixed on the surface of the recording medium.

  For example, Japanese Patent Application Laid-Open No. H11-163873 discloses "a fixing unit for fixing toner on a sheet, a curved section in which a sheet conveying path provided downstream of the fixing section in the sheet conveying direction is curved and extends in the conveying direction, A duct whose opening is opened and arranged radially outside of the curved portion of the paper transport path and extends in a paper width direction crossing the paper transport direction, and a duct of the duct for generating an airflow inside the duct. An image forming apparatus comprising two fans provided adjacent to an air inlet and arranged side by side in the sheet width direction and having the air intake side directed toward the fixing unit.

  Japanese Patent Application Laid-Open No. H11-163873 discloses a nip section between a first rotating body that contacts and heats an unfixed toner image formed on a sheet using a toner containing a release agent, and the first rotating body. A second rotator that sandwiches and conveys the sheet, a cover member that covers the outer surface of the first rotator at intervals, a fan, and air generated by the fan. And a duct leading toward an end, wherein the cover member extends from near the sheet entrance of the nip to the duct.

  Japanese Patent Application Laid-Open No. H11-163,199 discloses that a fixing member having a heating unit, a pressing member that forms a nip portion where a sheet holding a toner image in contact with the fixing member is sandwiched, and a pressing member near a paper outlet of the nip portion. A blower duct having a discharge port opened toward the air, a blower means for discharging air to the vicinity of the paper outlet via the blower duct, and a paper discharged from the nip disposed above the paper conveyance path. And a guide unit having a guide member for guiding the sheet, wherein the fixing unit fixes the toner image on the sheet by conveying the sheet holding the toner image in the nip portion while heating and pressing the sheet, and fixing the toner image on the sheet. A fixing device having an urging means for urging the paper toward the guide member in the vicinity of the fixing device is disclosed.

JP 2017-134103 A JP-A-2006-075781 JP 2011-209504 A

In recent years, there has been a demand for a toner having excellent low-temperature fixability due to a demand for energy saving, and has toner particles containing a release agent having a low melting temperature (for example, a release agent having a melting temperature of 100 ° C. or lower). Toner is used.
Further, from the viewpoint of enhancing the gloss (glossiness) of the image, the recording medium on which the toner image has been transferred has a first rotating body pair in which the outer peripheral surfaces thereof contact each other to form a first contact area. A first fixing unit that is inserted into the first contact area and heats, and a second rotating body pair that forms a second contact area by contacting the outer peripheral surfaces of the first fixing unit and that is inserted into the first contact area; A fixing unit including a second fixing unit that heats the recording medium by inserting the recording medium into the second contact area is used.
However, when a toner containing a release agent having a low melting temperature is used and a toner image is formed by performing fixing by the above-described fixing unit, the vaporized release agent is upstream of the first contact area in the first fixing unit. It has been found that particles having a particle diameter of 100 nm or less (so-called UFP; Ultra-Fine Particles) tend to be easily generated. Then, the generated particles (UFP) may be discharged to the outside of the image forming apparatus.

  An object of the present invention is to form a toner image formed by a developer containing a toner having toner particles containing a release agent having a melting temperature of 60 ° C. or more and 100 ° C. or less, and transferred to the surface of the recording medium. As a fixing means for fixing to the surface, the fixing device has a first rotating body pair in which outer peripheral surfaces thereof contact each other to form a first contact area, and a recording medium on which a toner image is transferred is inserted through the first contact area. A first fixing unit to be heated, and a second pair of rotating bodies that form a second contact area by contacting their outer peripheral surfaces with each other, and the recording medium inserted into the first contact area is moved to the second contact area. An image forming apparatus provided with a fixing unit having a second fixing unit for heating by passing through the first contact area on the recording medium conveying direction upstream of the first contact area and the surface of the recording medium having the toner image. Peripheral air supply inlet and second contact On the downstream side of the area in the recording medium transport direction and on the surface side having the toner image of the recording medium, the air supply outlets provided around the recording medium transport path are connected, and the gas entering from the air supply inlet is transmitted from the air supply outlet to the air supply outlet. An object of the present invention is to provide an image forming apparatus in which the amount of particles (UFP) having a particle diameter of 100 nm or less outside the apparatus is suppressed as compared with a case where an air supply pipe for exhausting air toward a recording medium is not provided.

  The above problem is solved by the following means.

<1>
An image carrier,
Charging means for charging the surface of the image holding member,
Electrostatic image forming means for forming an electrostatic image on the surface of the charged image carrier,
A developer containing a toner having toner particles containing a release agent having a melting temperature of 60 ° C. or more and 100 ° C. or less is contained, and the developer is used to develop an electrostatic charge image formed on the surface of the image holding member. Developing means for forming an image;
Transfer means for transferring the toner image to the surface of a recording medium,
Fixing means for fixing the toner image to the surface of the recording medium, comprising a first pair of rotating bodies that form a first contact area by contacting their outer peripheral surfaces with each other, wherein the toner image is transferred A first fixing unit that heats the recording medium by passing the recording medium through the first contact area; and a second pair of rotating bodies that form a second contact area by contacting their outer peripheral surfaces with each other. A fixing unit having a second fixing unit that heats the recording medium that has been inserted through the area by inserting the recording medium into the second contact area;
On the upstream side of the first contact area in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply inlet provided around the first contact area, and the air supply inlet of the second contact area. On the downstream side in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply outlet provided around the conveyance path of the recording medium is connected, and the gas supplied from the air supply inlet is supplied to the air supply port. An air pipe that exhausts air from the air outlet toward the recording medium;
An image forming apparatus comprising:
<2>
The image forming apparatus according to <1>, wherein a melting temperature of the release agent in the toner particles is from 60 ° C to 90 ° C.
<3>
The image forming apparatus according to <1> or <2>, wherein the release agent in the toner particles is paraffin wax.
<4>
The image forming apparatus according to any one of <1> to <3>, wherein the toner particles include a crystalline resin.
<5>
The image forming apparatus according to <4>, wherein the content of the crystalline resin is 3% by mass or more and 20% by mass or less based on the mass of the toner particles.
<6>
The image forming apparatus according to <5>, wherein the content of the crystalline resin is 5% by mass or more and 15% by mass or less based on the mass of the toner particles.
<7>
The image forming apparatus according to any one of <1> to <6>, wherein the toluene insoluble content of the toner particles is 25% by mass or more and 40% by mass or less.
<8>
The image forming apparatus according to any one of <1> to <7>, wherein the shape factor SF1 of the toner particles is 140 or more.

<9>
The air supply outlet is provided at a position where air can be exhausted from the recording medium after being inserted into the second contact area and before the heated toner image is completely solidified. The image forming apparatus according to any one of <1> to <8>.
<10>
In the transport path of the recording medium between the first fixing unit and the second fixing unit, the recording medium further includes a covering member that covers at least a part of the recording medium on the side having the toner image. 9> The image forming apparatus according to any one of the above.
<11>
The image forming apparatus according to any one of <1> to <10>, further including a rectifying plate that forms an airflow flowing from an end of the first contact area on the upstream side in the recording medium conveyance direction to the air supply inlet. apparatus.
<12>
The image forming apparatus according to any one of <1> to <11>, further including a unit configured to heat the inside of the air supply pipe.
<13>
The amount of heat given to the toner image on the recording medium by the heating in the first rotating body pair is smaller than the amount of heat given to the toner image on the recording medium by the heating in the second rotating body pair < The image forming apparatus according to any one of <1> to <12>.
<14>
The image forming apparatus according to <13>, wherein a set fixing temperature of the first rotating body pair is 100 ° C. or more and 200 ° C. or less.
<15>
The image forming apparatus according to <14>, wherein a set fixing temperature of the first rotating body pair is 120 ° C or more and 200 ° C or less.
<16>
The difference [T1-T2] between the fixing set temperature [T1] in the first rotating body pair and the melting temperature [T2] of the release agent in the toner particles is 40 ° C. or more and 120 ° C. or less, <14. > Or the image forming apparatus according to <15>.
<17>
Rotation of a belt rotator that contacts the surface of the recording medium having the toner image and heats the toner image, and a roll rotator that contacts the opposite surface of the recording medium. A roll body, wherein the second rotating body pair contacts the surface of the recording medium having the toner image and heats the toner image, and a roll contacts the opposite surface of the recording medium. The image forming apparatus according to any one of <1> to <16>, which is a pair of a rotating body and a rotating body.

According to the invention according to <1> or <17>, the toner is formed from a developer including toner having toner particles including a release agent having a melting temperature of 60 ° C or more and 100 ° C or less, and is transferred to the surface of a recording medium. A fixing unit for fixing the formed toner image to the surface of the recording medium, the recording medium having a first rotating body pair in which the outer peripheral surfaces thereof contact each other to form a first contact area; Has a first fixing unit for heating by passing through the first contact area, and a second pair of rotating bodies that form a second contact area by contacting their outer peripheral surfaces with each other, and is inserted into the first contact area. An image forming apparatus including a fixing unit having a second fixing unit that heats a recording medium after passing through the second contact area and includes a toner image on the recording medium upstream of the first contact area in the recording medium conveyance direction. On the surface side, around the first contact area At the air supply inlet, and at the downstream side of the second contact area in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply outlet provided around the conveyance path of the recording medium is connected, and the air supply inlet is connected to the air supply inlet. Provided is an image forming apparatus in which the amount of particles (UFP) having a particle diameter of 100 nm or less discharged outside the apparatus is suppressed as compared with a case where an air supply pipe for exhausting gas entering from an air supply outlet toward a recording medium is not provided. You.
According to the invention according to <2>, the fixing unit that fixes the toner image formed by the developer including the toner having the toner particles including the release agent and transferred onto the surface of the recording medium to the surface of the recording medium A first fixing unit that has a first pair of rotating bodies whose outer peripheral surfaces are in contact with each other to form a first contact area, and that inserts and heats the recording medium onto which the toner image has been transferred into the first contact area. And a second rotating body pair in which the outer peripheral surfaces of the rotating bodies contact each other to form a second contact area, and the recording medium inserted through the first contact area is inserted into the second contact area and heated. In an image forming apparatus provided with a fixing unit having a second fixing unit, a feeder provided around the first contact area on the upstream side in the recording medium transport direction of the first contact area and on the surface of the recording medium having the toner image. Air inlet, and below the recording medium transport direction of the second contact area On the side of the recording medium on the side having the toner image, the air supply outlets provided around the conveyance path of the recording medium are connected, and gas entering from the air supply inlet is exhausted from the air supply outlet toward the recording medium. An image forming apparatus in which the discharge amount of particles (UFP) having a particle diameter of 100 nm or less to the outside of the apparatus is suppressed even when the melting temperature of the release agent is 60 ° C. or more and 90 ° C. or less as compared with the case where the air supply pipe is not provided. Is provided.
According to the invention according to <3>, the toner image formed by the developer including the toner having the toner particles including the release agent having the melting temperature of not less than 60 ° C. and not more than 100 ° C. and transferred to the surface of the recording medium is formed. A fixing unit for fixing the recording medium onto which the toner image has been transferred; A first fixing unit that is inserted into the first heating unit and heats the recording medium; and a second pair of rotators that form a second contact area by contacting their outer peripheral surfaces. In the image forming apparatus including a fixing unit having a second fixing unit that is inserted into the second contact region and heats the second contact region, the first contact region is located on the upstream side in the recording medium conveyance direction and on the surface side of the recording medium having the toner image. (1) an air inlet provided around the contact area; On the downstream side of the second contact area in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply outlet provided around the conveyance path of the recording medium is connected, and gas supplied from the air supply inlet is supplied. Even if the release agent is paraffin wax, the amount of particles (UFP) having a particle size of 100 nm or less discharged to the outside of the apparatus is suppressed as compared with the case where the air supply pipe for exhausting air from the air outlet toward the recording medium is not provided. An image forming apparatus is provided.
According to the invention according to <4>, <5>, or <6>, the recording medium is formed of a developer including a toner having toner particles including a release agent having a melting temperature of 60 ° C or more and 100 ° C or less. As a fixing unit for fixing the toner image transferred to the surface of the recording medium to the surface of the recording medium, the first rotating body pair in which the outer peripheral surfaces thereof contact each other to form a first contact area, and the toner image is transferred A first fixing unit that inserts the heated recording medium into the first contact area and heats the recording medium; and a second pair of rotators that form a second contact area by contacting their outer peripheral surfaces. An image forming apparatus having a fixing unit having a second fixing unit for heating the recording medium inserted through the second contact area by inserting the recording medium into the second contact area, the recording medium being upstream of the first contact area in the recording medium conveyance direction and having a second position. On the side having the toner image, set around the first contact area. The air supply inlet provided in the vicinity of the recording medium conveyance path is connected to the air supply inlet on the downstream side of the second contact area in the recording medium conveyance direction and on the side of the recording medium having the toner image. Compared to the case where there is no air supply pipe for exhausting gas entering from the inlet toward the recording medium from the air supply outlet, even if the toner particles include a crystalline resin, particles (UPF) having a particle size of 100 nm or less are used. Provided is an image forming apparatus in which the amount of discharge to the outside of the apparatus is suppressed.
According to the invention according to <7>, compared to the case where the toluene-insoluble content of the toner particles is less than 25% by mass, the amount of particles (UFP) having a particle size of 100 nm or less discharged to the outside of the apparatus is suppressed. Is provided.
According to the invention according to <8>, the toner image formed by the developer including the toner having the toner particles including the release agent having the melting temperature of not less than 60 ° C. and not more than 100 ° C. and transferred to the surface of the recording medium can be formed. A fixing unit for fixing the recording medium onto which the toner image has been transferred; A first fixing unit that is inserted into the first heating unit and heats the recording medium; and a second pair of rotators that form a second contact area by contacting their outer peripheral surfaces. In the image forming apparatus including a fixing unit having a second fixing unit that is inserted into the second contact region and heats the second contact region, the first contact region is located on the upstream side in the recording medium conveyance direction and on the surface side of the recording medium having the toner image. (1) an air inlet provided around the contact area; On the downstream side of the second contact area in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply outlet provided around the conveyance path of the recording medium is connected, and gas supplied from the air supply inlet is supplied. Even when the air supply pipe for exhausting air from the air outlet to the recording medium is not provided, even if the shape factor SF1 of the toner particles is 140 or more, the discharge amount of the particles (UFP) having a particle diameter of 100 nm or less to the outside of the apparatus is reduced. An suppressed image forming apparatus is provided.

According to the invention according to <9>, the air supply outlet in the air supply pipe is inserted into the second contact region and the recording medium in a state after the heated toner image is completely solidified. Thus, an image forming apparatus is provided in which the amount of particles (UFP) having a particle size of 100 nm or less discharged to the outside of the apparatus is suppressed as compared with the case where the apparatus is provided at a position where air can be exhausted.
According to the invention according to <10>, the conveyance path of the recording medium from the first fixing unit to the second fixing unit does not include any covering member on the side of the recording medium having the toner image on the recording medium. Provided is an image forming apparatus in which the amount of particles (UFP) having a particle diameter of 100 nm or less outside the apparatus is suppressed.
According to the invention according to <11>, the particle diameter is 100 nm as compared with a case where there is no rectifying plate that forms an airflow that flows from the upstream end of the first contact area in the recording medium conveyance direction to the air supply inlet of the air supply pipe. An image forming apparatus is provided in which the amount of the following particles (UFP) discharged to the outside of the apparatus is suppressed.
According to the invention according to <12>, there is provided an image forming apparatus in which a discharge amount of particles (UFP) having a particle diameter of 100 nm or less to the outside of the apparatus is suppressed as compared with a case where there is no means for heating the inside of the air supply pipe. Provided.
According to the invention according to <13>, the amount of heat given to the toner image on the recording medium by heating at the first rotating body pair is changed to the amount of heat given to the toner image on the recording medium by heating at the second rotating body pair. An image forming apparatus is provided in which the amount of particles (UFP) having a particle size of 100 nm or less that is discharged to the outside of the apparatus is suppressed as compared with a case where the size is larger than the above.
According to the invention according to <14> or <15>, the amount of particles (UFP) having a particle diameter of 100 nm or less discharged out of the apparatus as compared with the case where the fixing set temperature in the first rotating body pair is higher than 200 ° C. An image forming apparatus is provided in which is suppressed.
According to the invention according to <16>, when the difference [T1-T2] between the fixing set temperature [T1] in the first rotating body pair and the melting temperature [T2] of the release agent in the toner particles is more than 120 ° C. An image forming apparatus is provided in which the amount of particles (UFP) having a particle diameter of 100 nm or less discharged outside the apparatus is suppressed.

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment. FIG. 2 is a schematic configuration diagram illustrating an example of a fixing device and an air supply pipe included in the image forming apparatus according to the embodiment. FIG. 2 is a schematic configuration diagram illustrating another example of a fixing device and an air supply pipe provided in the image forming apparatus according to the embodiment. FIG. 2 is a schematic configuration diagram illustrating another example of a fixing device and an air supply pipe provided in the image forming apparatus according to the embodiment. FIG. 2 is a schematic configuration diagram illustrating another example of a fixing device and an air supply pipe provided in the image forming apparatus according to the embodiment. FIG. 2 is a schematic configuration diagram illustrating another example of a fixing device and an air supply pipe provided in the image forming apparatus according to the embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges a surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image carrier, Developing means for containing a developer, developing the electrostatic image formed on the surface of the image carrier with the developer to form a toner image, and transferring means for transferring the toner image to the surface of a recording medium; Fixing means for fixing the toner image on the surface of the recording medium.
The developer contained in the developing means includes toner having toner particles containing a release agent having a melting temperature of 60 ° C. or more and 100 ° C. or less.
Further, the fixing unit has a first rotating body pair in which the outer peripheral surfaces thereof contact each other to form a first contact area (hereinafter, also simply referred to as “first nip”), and the fixing unit has the toner image transferred thereon. A first fixing unit that heats the recording medium by inserting the recording medium into the first contact area (first nip), and a second contact area (hereinafter, also simply referred to as “second nip”) in which the outer peripheral surfaces of the first fixing unit contact each other. A second fixing unit that has a second rotating body pair to be formed, and that heats the recording medium after being inserted into the first contact area (first nip) by inserting the recording medium into the second contact area (second nip); Having a part.
In the present embodiment, the first contact area (first nip) is further upstream of the first contact area (first nip) in the recording medium transport direction and on the side of the recording medium having the toner image. And an air supply inlet provided in the periphery of the recording medium, and a downstream side of the second contact area (second nip) in the recording medium transport direction and a surface side of the recording medium having the toner image. An air supply pipe is provided that connects an air supply outlet provided in the periphery and exhausts gas entering from the air supply inlet toward the recording medium from the air supply outlet.

In the following description, a toner for developing an electrostatic image having toner particles containing a release agent having a melting temperature of 60 ° C. or more and 100 ° C. or less may be referred to as “specific toner”.
In the following description, "upstream" refers to the upstream side in the recording medium transport direction, and "downstream" refers to the downstream side in the recording medium transport direction.

2. Description of the Related Art In recent years, image forming apparatuses have adopted a technique of fixing toner at a low temperature in order to reduce power consumption when fixing a toner image in response to a demand for energy saving. For example, in order to improve the low-temperature fixability, the developer contained in the developing unit of the image forming apparatus contains a release agent having a low melting temperature (for example, a release agent having a melting temperature of 100 ° C. or lower). Toner containing toner particles may be used.
Further, from the viewpoint of enhancing the gloss (glossiness) of an image to be formed, a method of performing fixing by applying pressure and heating in two stages in a fixing unit is adopted. For example, a first fixing unit that has a first rotating body pair in which the outer peripheral surfaces thereof contact each other to form a first nip, inserts a recording medium onto which a toner image has been transferred through the first nip, and heats the recording medium. A second fixing unit that has a second rotating body pair that forms a second nip by contacting the outer peripheral surfaces thereof and that inserts and heats the recording medium that has been inserted through the first nip into the second nip; A fixing unit (hereinafter, also simply referred to as “two-stage fixing unit in the present embodiment”) is used.

However, when an image is formed using a toner containing a release agent having a low melting temperature, the release agent has a low melting temperature when the toner image is heated and fixed to a recording medium by a fixing unit. It has been found that there is a tendency to be easily vaporized due to. In particular, it has been found that when fixing is performed by the two-stage fixing unit in the above-described embodiment, the amount of the release agent vaporized tends to be large on the upstream side of the first nip in the first fixing unit.
First, the reason why the release agent is easily vaporized in the first nip in the first fixing unit and the second nip in the second fixing unit will be compared. Since the recording medium having the toner image after the release agent has been vaporized in the first nip is inserted into the second nip, the vaporization is more likely during the heating in the first nip than in the second nip. It is considered that the amount of the releasing agent to be used tends to increase. Further, when the recording medium contains moisture (for example, when the recording medium is paper), the release agent is liable to be vaporized with the vaporization of the water. Therefore, it is considered that the first nip where heating is performed first is more likely to vaporize moisture from the recording medium, and that the amount of the release agent vaporized is more likely to increase.
Next, the ease of vaporization of the release agent on the upstream side and the downstream side in the first nip will be compared. In the first rotating body pair in the first fixing unit, heat is applied to the toner image on the recording medium from at least one of the rotating bodies. Since the surface temperature of the rotating body decreases from the point of contact with the recording medium (or the toner image held thereon), the surface temperature of the rotating body in the first nip is higher as it is closer to the upstream side. That is, the surface temperature of the rotating body in the first nip is highest at the upstream end. Therefore, in the first nip, when the toner image is inserted into the upstream end, the highest temperature is applied to the toner image, and the release agent of the release agent that is vaporized on the upstream side of the first nip is lower than on the downstream side. It is considered that the amount is likely to increase. In addition, as described above, when the recording medium contains water, the release agent is easily vaporized with the vaporization of the water, and the upstream side of the first nip where the heating is performed is performed first. It is conceivable that the vaporization of water from the recording medium is more likely to occur on the downstream side than on the downstream side, so that the amount of the release agent vaporized tends to increase.

The release agent vaporized as described above is re-coagulated in the air to form particles having a particle diameter of 100 nm or less (so-called “UFP (ultra fine particles)”) derived from the vaporized release agent. Then, the generated particles may be discharged to the outside of the image forming apparatus.
Therefore, it is required to reduce the discharge amount of particles (UFP) having a particle diameter of 100 nm or less out of the apparatus.

  On the other hand, the image forming apparatus according to the present embodiment has an air supply inlet upstream of the first nip and around the first nip on the toner image surface side of the recording medium, and downstream of the second nip and the recording medium. And an air supply pipe having an air supply outlet around the recording medium conveyance path on the side of the toner image. Therefore, particles (UFP) having a particle diameter of 100 nm or less derived from the vaporized release agent and generated on the upstream side of the first nip of the first fixing unit enter the air supply pipe from the air supply inlet together with the surrounding air. . Thereafter, the particles (UFP) are transported together with the air to the air supply outlet, and are exhausted from the air supply outlet toward the recording medium. The particles (UFP) that have arrived on the recording medium adhere to the surface of the toner image or an area where the toner image does not exist on the surface of the recording medium, and are conveyed to the outside of the apparatus together with the recording medium while being fixed on the recording medium. That is, the particles (UFP) generated from the release agent in the toner image are returned to and adhered to the recording medium through the air supply pipe, so that the particles (UFP) float in the air and are directly discharged out of the apparatus. It is considered that this is suppressed.

  In the present embodiment, as described above, the amount of particles (UFP) having a particle size of 100 nm or less outside the device is reduced.

  Here, "around the first contact area" where the air supply inlet is provided means a vapor generated from a toner image, a recording medium or the like in the first contact area and floated upstream, and the vaporized substance. Indicates a range from the air supply inlet to a distance at which particles generated by solidification again can be taken in. By providing the air supply inlet in this range, the release agent in the toner image is vaporized and re-solidified in the first contact area (first nip), and floats upstream of the first contact area. UFP is taken in from the air inlet.

  Further, “around the conveyance path of the recording medium” where the air supply outlet is provided means that the UFP contained in the air exhausted from the air supply outlet toward the recording medium is the surface of the toner image on the recording medium and the recording medium. It indicates a range up to a distance at which the toner can adhere to an area having no toner image on the surface. By providing the air supply outlet in this range, the UFP exhausted toward the recording medium adheres to the recording medium and is transported to the outside of the apparatus together with the recording medium in a state where the UFP is fixed to the recording medium. And is discharged to the outside of the apparatus as it is.

  Hereinafter, the configuration of the image forming apparatus according to the present embodiment will be described in detail.

Here, the image forming apparatus according to the present embodiment is an apparatus of a direct transfer system for directly transferring the toner image formed on the surface of the image carrier to a recording medium; Intermediate transfer type device for primary transfer to the surface of the transfer member and secondary transfer of the toner image transferred to the surface of the intermediate transfer member to the surface of the recording medium; after transfer of the toner image and before charging, the surface of the image carrier A well-known image forming apparatus such as an apparatus provided with a static eliminator for irradiating static elimination light to the surface is applied.
In the case of an intermediate transfer type device, the transfer device includes, for example, an intermediate transfer body on which a toner image is transferred on the surface, and a primary transfer for primarily transferring the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body. A configuration including a member and a secondary transfer member that secondary-transfers the toner image transferred on the surface of the intermediate transfer member onto the surface of the recording medium is applied.

  Note that, in the image forming apparatus according to the present embodiment, for example, a portion including at least the image holding member may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus.

  Here, the configuration of the image forming apparatus according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram illustrating a configuration of an example of an image forming apparatus according to the present embodiment.
As shown in FIG. 1, the image forming apparatus 10 according to the present embodiment is, for example, an intermediate transfer type image forming apparatus generally called a tandem type. Image forming units 1Y, 1M, 1C, and 1K, and a primary transfer unit 118 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 115. A secondary transfer unit 120 for collectively transferring (secondarily transferring) the superimposed toner image transferred on the intermediate transfer belt 115 to a sheet K (an example of a recording medium), and fixing the secondary transferred image on the sheet K And a fixing device 50 (an example of a fixing unit). Further, the image forming apparatus 10 has a control unit 140 that exchanges information with each device (each unit) and controls the operation of each device (each unit).
Note that a unit having the intermediate transfer belt 115, the primary transfer unit 118, and the secondary transfer unit 120 corresponds to an example of a transfer unit.

  Each of the image forming units 1Y, 1M, 1C, and 1K of the image forming apparatus 10 includes a photosensitive member 111 (an example of an image holding member) that rotates in the direction of an arrow A as an example of an image holding member that holds a toner image formed on the surface. ).

  Around the photoconductor 111, a charger 112 for charging the photoconductor 111 is provided as an example of a charging unit, and a laser exposure unit that writes an electrostatic charge image on the photoconductor 111 is provided as an example of an electrostatic image forming unit. 113 (an exposure beam is indicated by reference numeral Bm in the figure).

Around the photoconductor 111, as an example of a developing unit, there is provided a developing unit 114 that accommodates each color component toner and visualizes an electrostatic charge image on the photoconductor 111 with toner. A primary transfer roll 116 for transferring the respective color component toner images formed on the intermediate transfer belt 115 at the primary transfer unit 118 is provided.
Note that a specific toner is used as at least one of the above-described color component toners. In this embodiment, all the color component toners are preferably specific toners in terms of ensuring low-temperature fixability.

  Further, a photoconductor cleaner 117 for removing residual toner on the photoconductor 111 is provided around the photoconductor 111, and includes a charger 112, a laser exposure device 113, a developing device 114, a primary transfer roll 116, and a photoconductor cleaner. Electrophotographic devices 117 are sequentially arranged along the rotation direction of the photoconductor 111. These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 115. Have been.

  The intermediate transfer belt 115 is circulated (rotated) at various speeds in a direction B shown in FIG. The various rolls include a drive roll 131 driven by a motor (not shown) to rotate the intermediate transfer belt 115 and a support roll 132 that supports the intermediate transfer belt 115 extending substantially linearly along the direction in which the photoconductors 111 are arranged. , A tension applying roll 133 that functions as a correction roll that applies tension to the intermediate transfer belt 115 and suppresses the meandering of the intermediate transfer belt 115, a back roll 125 provided in the secondary transfer unit 120, and remains on the intermediate transfer belt 115. It has a cleaning back roll 134 provided in a cleaning unit for scraping toner.

The primary transfer unit 118 includes a primary transfer roll 116 as an opposing member that is disposed to face the photoconductor 111 with the intermediate transfer belt 115 interposed therebetween. The primary transfer roll 116 is composed of a core and a sponge layer as an elastic layer fixed around the core. The core is a cylindrical rod made of metal such as iron or SUS. The sponge layer is formed of a rubber blend of NBR, SBR and EPDM containing a conductive agent such as carbon black, and is a sponge-shaped cylindrical roll having a volume resistivity of ^107.5 Ωcm or more and ^108.5 Ωcm or less.

  The primary transfer roll 116 is pressed against the photoconductor 111 with the intermediate transfer belt 115 interposed therebetween, and the primary transfer roll 116 has a voltage (primary polarity) opposite to the polarity (negative polarity; the same applies hereinafter) of the toner. (Transfer bias) is applied. As a result, the toner images on the respective photoconductors 111 are sequentially electrostatically attracted to the intermediate transfer belt 115, and a superimposed toner image is formed on the intermediate transfer belt 115.

  The secondary transfer unit 120 includes a back roll 125 and a secondary transfer roll 122 disposed on the toner image holding surface side of the intermediate transfer belt 115.

The back roll 125 is made of a blend rubber tube of EPDM and NBR in which carbon is dispersed on the surface, and the inside is made of EPDM rubber. Then, the surface resistivity is formed to be 10 ⁷ Ω / □ or more and 10 ¹⁰ Ω / □ or less, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd .; the same applies hereinafter). You. The back roll 125 is disposed on the back side of the intermediate transfer belt 115 and forms a counter electrode of the secondary transfer roll 122. A metal power supply roll 126 to which a secondary transfer bias is stably applied is in contact with the back roll 125. ing.

On the other hand, the secondary transfer roll 122 includes a core and a sponge layer as an elastic layer fixed around the core. The core is a cylindrical rod made of metal such as iron or SUS. The sponge layer is formed of a rubber blend of NBR, SBR and EPDM containing a conductive agent such as carbon black, and is a sponge-shaped cylindrical roll having a volume resistivity of ^107.5 Ωcm or more and ^108.5 Ωcm or less.

  The secondary transfer roll 122 is pressed against the rear roll 125 with the intermediate transfer belt 115 interposed therebetween, and the secondary transfer roll 122 is further grounded to form a secondary transfer bias between the secondary transfer roll 122 and the rear roll 125. The toner image is secondarily transferred onto a sheet (an example of a recording medium) K conveyed to the transfer unit 120.

  On the downstream side of the secondary transfer section 120 of the intermediate transfer belt 115, an intermediate transfer belt for removing residual toner and paper dust on the intermediate transfer belt 115 after the secondary transfer and cleaning the surface of the intermediate transfer belt 115 A cleaner 135 is provided so as to be able to freely contact and separate.

  The intermediate transfer belt 115, the primary transfer unit 118 (primary transfer roll 116), and the secondary transfer unit 120 (secondary transfer roll 122) correspond to an example of a transfer unit.

  On the other hand, on the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 142 that generates a reference signal serving as a reference for setting an image forming timing in each of the image forming units 1Y, 1M, 1C, and 1K. It is arranged. An image density sensor 143 for adjusting image quality is provided downstream of the black image forming unit 1K. The reference sensor 142 recognizes a mark provided on the back side of the intermediate transfer belt 115 and generates a reference signal. In response to an instruction from the control unit 140 based on the recognition of the reference signal, each of the image forming units 1Y, 1Y, 1M, 1C, and 1K are configured to start image formation.

  Further, in the image forming apparatus according to the present embodiment, as a transport unit that transports the paper K, the paper storage unit 150 that stores the paper K, and the paper K accumulated in the paper storage unit 150 is taken out at a predetermined timing. Roll 151 for transporting the paper K fed by the paper feed roll 151, a transport guide 153 for feeding the paper K transported by the transport roll 152 to the secondary transfer unit 120, and secondary transfer The fixing device 50 includes a transport belt 155 that transports the paper K that is transported after the secondary transfer by the roll 122 to the fixing device 50 (an example of a fixing unit), and a fixing entrance guide 156 that guides the paper K to the fixing device 50.

  The control unit 140 is configured as a computer that controls the entire apparatus and performs various calculations. Specifically, for example, the control unit 140 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) storing various programs, and a RAM (Random Access Memory) used as a work area when executing the programs. ), A nonvolatile memory for storing various information, and an input / output interface (I / O) (all not shown). Each of the CPU, ROM, RAM, nonvolatile memory, and I / O is connected via a bus.

  The image forming apparatus 10 includes an operation display unit, an image processing unit, an image memory, a storage unit, a communication unit, and the like in addition to the control unit 140 (all are not shown). The operation display unit, the image processing unit, the image memory, the storage unit, and the communication unit are connected to the I / O of the control unit 140. The control unit 140 exchanges information with the operation display unit, the image processing unit, the image memory, the storage unit, and the communication unit to control each unit. The fixing set temperature is also controlled by the control unit 140.

Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described.
In the image forming apparatus according to the present embodiment, image data output from an image reading device (not shown), a personal computer (PC) not shown, or the like is subjected to image processing by an image processing device (not shown), and then the image forming unit 1Y , 1M, 1C, and 1K perform an image forming operation.

  The image processing apparatus performs image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, various image editing such as frame erasing, color editing, and moving editing on the input reflectance data. Is done. The image data subjected to the image processing is converted into four color material gradation data of Y, M, C, and K, and output to the laser exposure device 113.

  The laser exposure device 113 irradiates, for example, an exposure beam Bm emitted from a semiconductor laser to each of the photoconductors 111 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. . In each of the photoconductors 111 of the image forming units 1Y, 1M, 1C, and 1K, after the surface is charged by the charger 112, the surface is scanned and exposed by the laser exposure device 113 to form an electrostatic image. The formed electrostatic image is developed by each of the image forming units 1Y, 1M, 1C, and 1K as a toner image of each color of Y, M, C, and K.

  The toner images formed on the photoconductors 111 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 115 at a primary transfer unit 118 where the respective photoconductors 111 and the intermediate transfer belt 115 are in contact. You. More specifically, in the primary transfer section 118, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (minus polarity) of the toner is applied to the base material of the intermediate transfer belt 115 by the primary transfer roll 116, and the toner image is formed. Are sequentially superimposed on the surface of the intermediate transfer belt 115 to perform primary transfer.

  After the toner image is sequentially primary-transferred onto the surface of the intermediate transfer belt 115, the intermediate transfer belt 115 moves and the toner image is transported to the secondary transfer unit 120. When the toner image is transported to the secondary transfer unit 120, the transport unit rotates the paper feed roll 151 in synchronization with the timing at which the toner image is transported to the secondary transfer unit 120, and moves the paper roll 151 from the paper storage unit 150 to the target. Paper K of a size is supplied. The paper K supplied by the paper feed roll 151 is transported by the transport roll 152 and reaches the secondary transfer unit 120 via the transport guide 153. Before reaching the secondary transfer unit 120, the sheet K is temporarily stopped, and the alignment roller (not shown) is rotated in accordance with the movement timing of the intermediate transfer belt 115 holding the toner image, so that the sheet K is rotated. And the position of the toner image are aligned.

  In the secondary transfer unit 120, the secondary transfer roll 122 is pressed against the back roll 125 via the intermediate transfer belt 115. At this time, the sheet K conveyed in a timely manner is sandwiched between the intermediate transfer belt 115 and the secondary transfer roll 122. At this time, when a voltage (secondary transfer bias) having the same polarity as the charging polarity (minus polarity) of the toner is applied from the power supply roll 126, a transfer electric field is formed between the secondary transfer roll 122 and the back roll 125. Is done. Then, the unfixed toner image held on the intermediate transfer belt 115 is collectively electrostatically transferred onto the sheet K in the secondary transfer unit 120 pressed by the secondary transfer roll 122 and the back roll 125. You.

  Thereafter, the sheet K on which the toner image has been electrostatically transferred is conveyed as it is separated from the intermediate transfer belt 115 by the secondary transfer roll 122, and is provided on the downstream side of the secondary transfer roll 122 in the sheet conveying direction. It is transported to the belt 155. The transport belt 155 transports the sheet K to the fixing device 50 in accordance with the optimal transport speed of the fixing device 50. The unfixed toner image on the sheet K conveyed to the fixing device 50 undergoes a fixing process by heat and pressure by the fixing device 50 and is fixed on the sheet K. Then, the sheet K on which the fixed image is formed is conveyed to a sheet discharge storage unit (not shown) provided in a discharge unit of the image forming apparatus.

  On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 115 is conveyed to the cleaning unit with the rotation of the intermediate transfer belt 115, and is cleaned by the cleaning back roll 134 and the intermediate transfer belt cleaner 135. The toner is removed from the intermediate transfer belt 115.

[Fixing means]
The fixing unit according to the exemplary embodiment includes a first pair of rotating members whose outer peripheral surfaces are in contact with each other to form a first contact region (a first nip), and the first contact member contacts the recording medium onto which the toner image has been transferred. A first fixing unit that is inserted into the region (first nip) and heats, and a second rotating body pair that forms a second contact region (second nip) by contacting the outer peripheral surfaces of the first fixing unit and the first fixing unit; A second fixing unit that heats the recording medium inserted through the contact area (first nip) through the second contact area (second nip);

  As described above, by adopting the method of performing fixing by applying pressure and heating in two stages, having the first fixing unit and the second fixing unit, the total amount of heat applied to the unfixed toner image , The fixing set temperature in each fixing unit can be reduced. Therefore, energy saving by low-temperature fixing can be achieved while securing the fixing strength of the image.

  Further, in the case of a system in which fixing is performed by applying pressure and heating in two stages, both fixing units can play different roles. For example, the first fixing unit can play a role of improving the fixability of the toner image, and the second fixing unit can play a role of improving the smoothness of the surface of the toner image, thereby securing the fixing strength of the image. In addition, an image with high gloss (gloss) can be obtained.

In the present embodiment, it is necessary that the amount of heat given to the toner image on the recording medium by the heating by the first rotating body pair is smaller than the amount of heat given to the toner image on the recording medium by the heating by the second rotating body pair. preferable.
As a result, the fixing set temperature at the first rotating body pair is reduced, that is, the temperature of the heat applied to the toner image in the first contact area (first nip) is reduced, so that the release agent contained in the toner image is reduced. And the like, and the amount of vaporizing moisture in the recording medium can be suppressed. As a result, the amount of UFP generated on the upstream side of the first nip can be easily suppressed.
Further, the heat quantity at the first rotating body pair is made smaller than the heat quantity at the second rotating body pair, so that the first fixing unit plays a role of improving the fixability of the toner image, and the second fixing unit makes the toner fixation. It can play a role in enhancing the smoothness of the surface of the image. This makes it easy to obtain an image with high gloss (gloss) while securing the fixing strength of the image.
The “heat amount” is represented by a product of a temperature of heat applied to the toner image and a time during which heat is applied to the toner image. Therefore, control is performed by the fixing set temperature in the first or second rotating body pair, the width of the first contact area (first nip) or the second contact area (second nip) in the recording medium transport direction, and the transport speed of the recording medium. Is done.

The fixing set temperature in the first rotating body pair is preferably from 100 ° C to 200 ° C, more preferably from 120 ° C to 200 ° C, and even more preferably from 140 ° C to 180 ° C.
When the fixing temperature of the first rotating body pair is equal to or higher than 100 ° C., it is easy to secure the image fixing property. On the other hand, when the fixing set temperature of the first rotating body pair is 200 ° C. or less, it is easy to achieve energy saving by low-temperature fixing, and it is easy to suppress the amount of UFP generated upstream of the first nip.

On the other hand, the set fixing temperature of the second rotating body pair is preferably 140 ° C. or more and 220 ° C. or less, more preferably 160 ° C. or more and 220 ° C. or less, and more preferably 170 ° C. or more and 210 ° C. or less. preferable.
When the fixing set temperature of the second rotating body pair is 140 ° C. or higher, an image with high gloss (glossiness) can be easily obtained. On the other hand, when the fixing set temperature of the second rotating body pair is 220 ° C. or less, it is easy to achieve energy saving by low-temperature fixing.

  The difference between the fixing set temperatures of the first rotating body pair and the second rotating body pair (the temperature of the second rotating body pair-the temperature of the first rotating body pair) is determined by the gloss (gloss) while securing the fixing strength of the image. The temperature is preferably from 10 ° C. to 80 ° C., more preferably from 20 ° C. to 60 ° C., and even more preferably from 20 ° C. to 40 ° C.

Here, the fixing set temperature in the first rotating body pair and the second rotating body pair will be described.
Heating of each of the first pair of rotators and the second pair of rotators is normally performed by the rotator that contacts the toner image. For example, the rotating body that comes into contact with the surface of the recording medium having the toner image is a heating / pressing rotating body having a heating mechanism on at least one of the inside and the outside, and the surface side of the recording medium that does not have the toner image. In this case, the rotating body that contacts the surface is a pressure rotating body that pressurizes without heating. However, both the rotating body that contacts the surface having the toner image and the rotating body that contacts the surface having the toner image may have a role of heating.
Further, the fixing set temperature in the first rotating body pair and the second rotating body pair means that the temperature of the first rotating body pair or the second rotating body pair is in contact with the toner image on the surface of each rotating body that is in contact with the toner image. The target value of the temperature at the point where In other words, it indicates the target value of the surface temperature of the rotating body at the moment when it comes into contact with the toner image and heat has not yet moved to the toner image.

In the present embodiment, the first rotating member pair contacts the surface of the recording medium having the toner image and heats the toner image, and the opposite rotating surface of the recording medium (that is, the surface having no toner image). ), The second rotating member pair being in contact with the surface of the recording medium having the toner image and heating the toner image. It is preferable to use a rotating body pair of a body and a roll rotating body that comes into contact with the opposite surface of the recording medium (that is, a two-roll rotating body pair).
In the above-described belt-roll rotating body pair, the width of the contact area (nip) in the recording medium transport direction can be increased, that is, the time for applying heat to the toner image can be increased. Therefore, when the first rotating body pair is in this mode, the fixing set temperature can be reduced while securing the applied heat amount, and it is easy to achieve energy saving by low-temperature fixing while securing the fixing strength of the image. And it becomes easy to suppress the amount of UFP generated on the upstream side of the first nip.
Further, in the above-described two-roll rotating body pair, a high pressure can be applied to the toner image. Therefore, when the second rotating body pair is in this mode, an image having high gloss (glossiness) can be easily obtained.

However, the fixing unit in the present embodiment is not limited to this mode. The first rotator pair and the second rotator pair may take, for example, a belt rotator that contacts the surface of the recording medium having the toner image and heats the toner image, and a surface on the opposite side of the recording medium. A pair of a rotating body with a roll rotating body (that is, a belt-roll rotating body pair) that comes into contact with the surface of the recording medium; a roll rotating body that contacts the surface of the recording medium having the toner image and heats the toner image; Rotating body pair with a belt rotating body that comes into contact with the recording medium (that is, a roll-belt rotating body pair); a roll rotating body that contacts the surface of the recording medium having the toner image and heats the toner image; Rotating body pair with a roll rotating body that comes into contact with the recording medium (that is, a two-roll rotating body pair); a belt rotating body that contacts the surface of the recording medium having the toner image and heats the toner image; The rotating body pair (the pin 2 belt rotating body pair), and the like.
Further, as the above-mentioned belt rotating body, an IH (induction heating) heating type belt rotating body using a belt rotating body having a metal layer may be used.
In the present embodiment, these pairs of rotating bodies can be freely used as the first rotating body pair and the second rotating body pair.

Here, the fixing unit in the present embodiment will be described with reference to the drawings.
The fixing device 50 illustrated in FIGS. 1 and 2 is an example of a fixing unit.

FIG. 2 is a schematic configuration diagram showing the fixing device 50 and the duct 100 in the image forming apparatus 10 in an enlarged manner.
The fixing device 50 includes, as a first fixing unit, a pressure roll 61 that contacts and presses a surface of the sheet K (an example of a recording medium) that does not have a toner image while rotating, and a sheet K that rotates while driving. And a heating belt 62 for applying pressure and heat in contact with the surface having the toner image. The pressure roll 61 and the heating belt 62 are an example of a first rotating body pair, and a region where the pressure roll 61 and the heating belt 62 are in contact forms a first nip (first contact region) N6. I have.
On the downstream side of the pressure roll 61 and the heating belt 62, as a second fixing unit, a roller that contacts and presses the surface of the sheet K (an example of a recording medium) having no toner image while rotating is driven. A pressure roll 34 and a heating roll 32 that presses and heats the paper K while contacting with the surface of the paper K having the toner image while being driven to rotate. The pressure roll 34 and the heating roll 32 are an example of a second rotating body pair, and a region where the pressure roll 34 and the heating roll 32 are in contact forms a second nip (second contact region) N6. I have.

(First fixing unit)
Heating belt As the heating belt 62, for example, a belt using a resin material or a metal material may be used. The heating belt 62 may be a belt having a single layer configuration or a belt having a multilayer configuration in which a plurality of layers are stacked.

As a belt having a single-layer structure, a belt using a resin material is exemplified. Examples of the resin material include a resin generally called an engineering plastic.
Examples of engineering plastics include fluororesin, polyimide (PI, thermosetting polyimide, thermoplastic polyimide), fluorinated polyimide, polyamideimide (PAI), polybenzimidazole (PBI), polyetheretherketone (PEEK), and polysulfone. (PSU), polyether sulfone (PES), polyphenylene sulfide (PPS), polyetherimide (PEI), wholly aromatic polyester (liquid crystal polymer) and the like. Among them, polyimide, fluorinated polyimide, polyamide imide, polyether imide and the like are preferable in terms of mechanical strength, heat resistance, abrasion resistance and the like.

  In addition, as a belt having a single-layer structure, a belt using a metal material is exemplified. Examples of the metal material include various metals such as SUS, nickel, copper, and aluminum.

  Further, as a belt having a laminated configuration, for example, a belt in which a base material, an elastic layer, and a surface layer are laminated in this order is exemplified.

  Examples of the base material include those using a resin material or a metal material. Examples of these materials include the resin materials and the metal materials listed in the above-described single-layer belt. Note that a base material may be formed by stacking a resin material layer and a metal material layer.

The elastic layer is a layer provided from the viewpoint of imparting elasticity to pressure applied to the heating belt 62 from the outer peripheral side.
Examples of the material of the elastic layer include a fluorine resin, a silicone resin, a silicone rubber, a fluorine rubber, a fluorosilicone rubber, and the like. From the viewpoint of heat resistance, thermal conductivity, insulation, and the like, for example, silicone rubber is preferable.

For example, heat resistance and mold release properties are required for the surface layer. From this viewpoint, it is preferable to use a heat-resistant release material as a material constituting the surface layer, and specific examples thereof include fluororubber, fluororesin, silicone resin, and polyimide resin.
Among these, a fluorine resin is preferable as the heat-resistant release material.
Specific examples of such a fluororesin include tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and polyethylene. -Tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychloroethylene trifluoride (PCTFE), vinyl fluoride (PVF) and the like.

  Note that an adhesive layer may be provided between at least one of the substrate and the elastic layer and between the elastic layer and the surface layer.

・ Pressing pad The pressing roller 61 is pressed on the inner side of the heating belt 62 via the heating belt 62 to form a first nip N6 through which the sheet K passes between the heating belt 62 and the pressing roller 61. The pad 64 is provided. Further, a belt traveling guide 63 and a belt traveling auxiliary guide 66 are provided inside the heating belt 62, and the heating belt 62 is arranged along the outer peripheral surfaces of the belt traveling guide 63, the belt traveling auxiliary guide 66, and the pressing pad 64. It is configured to move around. The belt running guide 63 and the pressing pad 64 are attached to the holder 65 inside the heating belt 62. A heating element 69 is provided between the belt running guide 63 and the heating belt 62 as a heating source for the heating belt 62.

  The pressing pad 64 is supported by a holder 65 made of metal, for example, inside the heating belt 62. The pressing pad 64 is arranged so as to face the pressure roll 61 via the heating belt 62, and presses the heating belt 62 from the inner peripheral surface of the heating belt 62 to the pressure roll 61, and the heating belt 62 and the pressure roll 61, a first nip N6 through which the sheet K passes is formed.

  The heating belt 62 and the pressure roll 61 only need to be relatively pressed, and therefore, the heating belt 62 may be pressed toward the pressure roll 61 by the pressing pad 64. The pressure roll 61 may be pressed toward the heating belt 62 side.

  The material of the pressing pad 64 is, for example, a resin such as silicone rubber, fluorine rubber, polyimide resin, polyamide resin, phenol resin, PES resin (polyethersulfone), PPS resin (polyphenylene sulfide), or a metal such as iron or aluminum. And the like. The resin may further contain conductive particles such as carbon black, graphite, and metal powder.

Belt running guide and belt running assist guide The belt running guide 63 and the belt running assist guide 66 are provided in an arc shape inside the heating belt 62 so as to conform to the shape of the heating belt 62 so that the heating belt 62 can move around. To support.
The material of the belt traveling guide 63 and the belt traveling auxiliary guide 66 is, for example, a heat-resistant resin such as polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), liquid crystal polymer (LCP), and further, durability. And a filler obtained by adding a filler for lowering the friction coefficient to the heat-resistant resin.

Heating Element As a heating source for applying heat to the heating belt 62, a heating element 69 is provided between the belt travel guide 63 and the heating belt 62.
The heating element 69 has, for example, an arc shape along the shape of the heating belt 62. As the heating element, for example, a resistance heating element that generates Joule heat by supplying power is sandwiched between a pair of support plates, and heat generated from the resistance heating element is applied to the heating belt 62 via the support plate. An example of the transmitted mode is given. The material of the support plate is preferably a metal such as aluminum or stainless steel from the viewpoint of heat conductivity. In addition, the heating source of the fixing device 50 is not limited to the heating element, and for example, a known heating source such as a halogen lamp may be used.

Pressure Roll The pressure roll 61 is disposed, for example, around a solid metal core (cylindrical core) 61A, an elastic layer 61B disposed around the core 61A, and a periphery of the elastic layer 61B. It is a cylindrical roll provided with a surface layer 61C. The pressure roll 61 is not limited in its shape, structure, size and the like, and a known pressure roll is used depending on the purpose.

  Both ends of the core 61A are rotatably supported by, for example, bearing members (not shown), and are predetermined with respect to the heating belt 62 by urging members such as coil springs disposed at both ends of the core 61A. It is pressed by pressure.

  Examples of the material of the core 61A of the pressure roll 61 include metals or alloys having high thermal conductivity such as iron, aluminum (for example, A-5052), SUS, copper, etc., ceramics, and fiber reinforced metal (FRM). Can be

  Examples of the material of the elastic layer 61B of the pressure roll 61 include rubber, elastomer, foamed resin and the like having a hardness (JIS-A: hardness measured by a JIS-KA type testing machine) of 15 ° or more and 60 ° or less. More specifically, examples thereof include silicone rubber, fluorine rubber, and liquid silicone rubber filled with hollow glass beads.

  The material of the surface layer 61C of the pressure roll 61 is, for example, resin. Examples of the resin forming the surface layer 61C include tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), polytetrafluoroethylene (PTFE), and tetrafluoroethylene Fluororesins such as hexafluoropropylene copolymer (FEP), silicone resins, silicone rubbers, fluororubbers, fluorinated polyimides and the like are included.

  Note that an adhesive layer may be provided between at least one of the core 61A and the elastic layer 61B and between the elastic layer 61B and the surface layer 61C.

  In the above-described configuration, the pressure roll 61 is rotated by, for example, a drive motor (not shown), and the heating belt 62 rotates in a direction opposite to the rotation direction of the pressure roll 61 following this rotation. That is, for example, while the pressure roll 61 rotates clockwise in FIG. 2, the heating belt 62 rotates counterclockwise.

(Second fixing unit)
Heating Roll The heating roll 32 has a cylindrical core material 32A, an elastic layer 32B covering the core material 32A, and a surface layer 32C covering the elastic layer 32B. Note that an adhesive layer may be provided between at least one of the core material 32A and the elastic layer 32B and between the elastic layer 32B and the surface layer 32C.
A heating source 32D that heats the heating roll 32 from the inner peripheral side is disposed inside the heating roll 32.

Examples of the material of the core material 32A include metals such as stainless steel (SUS), iron and copper, alloys, fiber reinforced metal (FRM), and ceramics.
As a material of the elastic layer 32B, for example, silicone rubber, fluorine rubber, or the like can be used.
The material of the surface layer 32C includes, for example, fluororubber, silicone rubber, fluororesin, etc., but fluororesin is preferred from the viewpoint of releasability.

The heating source 32D includes, for example, a single or a plurality of halogen lamps. The heating source is not limited to the halogen lamp, and another heating member that generates heat may be used.
The heat generated from the heating source 32D is transmitted through the core material 32A, the elastic layer 32B, and the surface layer 32C, so that the surface temperature of the heating roll 32 is increased.

Pressure Roll The pressure roll 34 has a cylindrical core material 34A, an elastic layer 34B covering the core material 34A, and a surface layer 34C covering the elastic layer 34B. An adhesive layer may be provided between at least one of the core material 34A and the elastic layer 34B and between at least one of the elastic layer 34B and the surface layer 34C.
Both ends of the core 34A are supported by a support member such that the pressure roll 34 rotates, and the urging member urges the pressure roll 34 toward the heating roll 32 via the support member. Thus, the pressing roll 34 presses the conveyed paper K toward the heating roll 32.

  Preferred examples of the material of the core material 34A, the elastic layer 34B, the surface layer 34C, and the adhesive layer are the same as the material of the core material 32A, the elastic layer 32B, the surface layer 32C, and the adhesive layer in the heating roll, respectively. The same is true.

  In the above configuration, for example, the pressure roll 34 is rotated by a drive motor (not shown), and the heating roll 32 is rotated by the rotation. That is, for example, while the pressing roll 34 rotates clockwise in FIG. 2, the heating roll 32 rotates counterclockwise.

  Next, the operation of the fixing device 50 will be described.

  In the fixing device 50, first, a sheet K having a toner image is inserted through the first nip N6 in the pressure roll 61 and the heating belt 62, which are examples of the first fixing unit. Specifically, the pressure roll 61 is rotated by a drive motor (not shown), and the heating belt 62 rotates in a direction opposite to the rotation direction of the pressure roll 61 following this rotation. Then, the sheet K on which the unfixed toner image is formed is guided by the fixing entrance guide 156 (see FIG. 1), and is conveyed to the first nip N6 formed by the heating belt 62 and the pressure roll 61. Is done. When the sheet K passes through the first nip N6, pressure and heat acting on the first nip N6 are applied to the toner image on the sheet K, and then the sheet K is discharged from the first nip N6.

Next, the sheet K discharged from the first nip N6 formed by the pressure roll 61 and the heating belt 62 passes through the second nip N3 in the pressure roll 34 and the heating roll 32, which are examples of the second fixing unit. Is done. More specifically, the pressure roll 34 is rotated by a drive motor (not shown), and the heating roll 32 rotates in a direction opposite to the rotation direction of the pressure roll 34 following this rotation. Then, the sheet K discharged from the first nip N6 is transported to the second nip N3 formed by the heating roll 32 and the pressure roll. When the sheet K passes through the second nip N3, pressure and heat acting on the second nip N3 are applied to the toner image on the sheet K, and then the sheet K is discharged from the second nip N3.
Thus, the toner image is fixed on the surface of the sheet K by the pressure roll 61 and the heating belt 62 and the pressure roll 34 and the heating roll 32.

[Air pipe]
The image forming apparatus according to the present embodiment is provided around the first nip on the upstream side of the first contact area (first nip) in the fixing unit in the recording medium conveyance direction and on the surface of the recording medium having the toner image. An air supply inlet and an air supply outlet provided around the conveyance path of the recording medium are connected on the downstream side of the second contact area (second nip) in the recording medium conveyance direction and on the side of the recording medium having the toner image. And an air supply pipe for exhausting gas entering from the air supply inlet toward the recording medium from the air supply outlet.

  Thus, by providing the air supply pipe connecting the air supply inlet and the air supply outlet, a particle diameter of 100 nm or less derived from a vaporized release agent generated upstream of the first nip of the first fixing unit. The particles (UFP) are conveyed to the air supply outlet and exhausted from the air supply outlet toward the recording medium. Then, the particles (UFP) are conveyed to the outside of the apparatus together with the recording medium in a state where the particles (UFP) adhere to and are fixed on the recording medium, so that the particles (UFP) are prevented from drifting in the air and directly discharged out of the apparatus. Is done. That is, the amount of particles (UFP) having a particle size of 100 nm or less discharged outside the apparatus is reduced.

Here, the air supply pipe in the present embodiment will be described with reference to the drawings.
The duct 100 shown in FIG. 2 is an example of an air supply pipe.

  The duct 100 is on the upstream side of the first nip (first contact area) N6 formed by the pressure roll 61 and the heating belt 62 corresponding to the first rotating body pair, and on the surface side of the sheet K having the toner image. Has an air supply inlet 102 provided around the first nip N6. Further, on the downstream side of the second nip (second contact area) N3 formed by the pressure roll 34 and the heating roll 32 corresponding to the second rotating body pair, and on the side of the sheet K having the toner image, An air supply outlet 104 is provided around the paper K transport path. The air supply inlet 102 and the air supply outlet 104 are connected by a duct 100 that passes through the opposite side of the heating belt 62 and the heating roll 32 from the paper K transport path (that is, the upper side of the heating belt 62 and the heating roll 32 in FIG. 2). ing.

  The air around the first nip N6 on the upstream side of the first nip N6 and on the side of the sheet K having the toner image enters the duct 100 from the air supply inlet 102 as indicated by an arrow U1. Then, this air is supplied to the air supply outlet 104 through the duct 100 as shown by an arrow U2, and further exhausted from the air supply outlet 104 toward the sheet K as shown by an arrow U3.

The duct 100 shown in FIG. 2 has fans 106 and 108 inside. By providing the fans 106 and 108, an airflow is forcibly generated in the duct 100, so that air is generated at the air supply inlet 102 and the exhaust force at the air supply outlet 104 is increased. This makes it easier to take in the air around the first nip N6 and the UFP on the upstream side of the first nip N6 and on the side of the sheet K having the toner image from the air supply inlet 102. Further, the air can be exhausted from the air supply outlet 104 toward the paper K with stronger wind force, and the UFP can be easily attached to the paper K.
The number of fans provided in the duct 100 is not particularly limited. For example, a plurality of fans may be arranged side by side in the width direction of the duct 100. Although the fans 106 and 108 are provided at two locations in the air supply direction in FIG. 2, the number of installations in the air supply direction may be one or three or more.

  In the present embodiment, a device for forcibly generating an airflow such as a fan may not be provided inside the duct 100. In this case, on the upstream side of the first nip N6, the air around the upstream side of the first nip N6 is changed according to the flow of the airflow generated by the conveyance of the sheet K, the rotation of the heating belt 62 and the pressure roll 61, and the like. A configuration that naturally enters the air supply inlet 102 can be adopted. Note that this configuration can be achieved by adjusting the shape and arrangement position of the air supply inlet 102 and the like.

The shape of the duct 100 in a cross section perpendicular to the air supply direction has a long side in the width direction (the same direction as the axial direction of the pressure roll 61, the heating belt 62, the pressure roll 34, and the heating roll 32). It is a rectangular corner shape. The shape of the duct 100 in a cross section perpendicular to the air supply direction is the same as the entire duct 100 except for the air supply inlet 102.
However, the cross-sectional shape of the duct 100 is not limited to this, and may be, for example, a round shape or an elliptical shape.

The length in the width direction of the inside of the duct 100 (that is, the air flow path portion) is set to be longer than the width direction length of the sheet K (the width direction length of the maximum width sheet that can be inserted into the image forming apparatus). I have. Specifically, it is preferable that the paper K has a width that is 10 mm or more and 30 mm or less at both ends with respect to the width direction length. It is preferable that the length in the width direction of the inside of the duct 100 is equal over the entire duct 100 from the viewpoint of making the air supply amount nearly uniform over the entire duct 100.
The area of the cross section perpendicular to the air supply direction inside the duct 100 (that is, the air flow path portion) is freely set according to the amount of air to be supplied. It is preferable that the area of the cross section perpendicular to the air supply direction inside the duct 100 is equal over the entire duct 100 from the viewpoint of making the air supply amount nearly uniform over the entire duct 100.

As shown in FIG. 2, the path of the duct 100 is directed from the air supply inlet 102 to a direction away from the paper K transport path (that is, the upper side in FIG. 2), and then is bent at a right angle in the paper transport direction, and the heating belt 62 and The heating roll 32 passes through the opposite side of the paper K transport path (that is, the upper side of the heating belt 62 and the heating roll 32 in FIG. 2), and is further bent at a right angle in the transport path direction of the paper K. It is connected to the air supply outlet 104 provided.
However, the path of the duct 100 is not limited to this, and may have a curved path, for example, instead of a path that is bent at a right angle as shown in FIG.

  The material of the duct 100 is not particularly limited, and a conventionally known material having heat resistance is used. Examples thereof include metal materials and the like, and specific examples include a steel sheet, a plated steel sheet (for example, a galvanized steel sheet, an alloy-plated steel sheet), a stainless steel sheet, and a vinyl chloride-coated steel sheet.

-Air supply inlet The shape of the air supply inlet 102 is inclined with respect to the sheet K transport path when viewed from the axial direction of the heating belt 62 and the pressure roll 61, so that the air supply inlet 102 is in the first nip N6. Has a shape oriented in the direction of. That is, the end 102A of the air supply inlet 102 on the side closer to the heating belt 62 is farther from the conveyance path of the paper K, and the end 102B of the air supply inlet 102 farther from the heating belt 62 is closer to the conveyance path of the paper K. Is located in the position. Since the end 102A and the end 102B are linearly connected, the air supply inlet 102 is arranged so as to face the first nip N6.
Since the air supply inlet 102 has a shape oriented in the direction of the first nip N6, the release agent-derived UFP generated on the upstream side of the first nip N6 is easily taken in from the air supply inlet 102.

  The vicinity of the first nip N6 where the air supply inlet 102 is provided is defined as a vapor generated from the toner image, the paper K and the like in the first nip N6 and floating on the upstream side, and the vaporized substance. It indicates a range from the air supply inlet 102 to a distance at which particles or the like generated by solidification again can be taken in.

Here, the distance from each part of the air supply inlet 102 will be described. From the viewpoint that the release agent-derived UFP generated on the upstream side of the first nip N6 is easily taken in from the air supply inlet 102, the distance from each part of the air supply inlet 102 is preferably in the following range.
The end 102A of the air supply inlet 102 on the side close to the heating belt 62 is preferably installed at a distance of 10 mm or more and 40 mm or less (more preferably 10 mm or more and 30 mm or less) from the upstream end of the first nip N6.
The end portion 102A is preferably set at a distance of 10 mm or more and 50 mm or less (more preferably, 10 mm or more and 30 mm or less) from the surface of the heating belt 62.
The end portion 102A is preferably installed at a distance of 10 mm or more and 40 mm or less (more preferably, 10 mm or more and 30 mm or less) from the paper K transport path.

The end 102B of the air supply inlet 102 on the side remote from the heating belt 62 is preferably installed at a distance of 20 mm or more and 60 mm or less (more preferably 20 mm or more and 50 mm or less) from the upstream end of the first nip N6.
The end portion 102B is preferably set at a distance of 20 mm or more and 60 mm or less (more preferably, 20 mm or more and 50 mm or less) from the paper K transport path.

Rectifier Plate A rectifier plate 110 that forms an airflow flowing from the upstream end of the first nip N6 to the air supply inlet 102 is provided at the air supply inlet 102 of the duct 100.
By providing the current plate 110, UFP generated from the release agent generated on the upstream side of the first nip N6 is easily taken in from the air supply inlet 102.

In FIG. 2, one end of the current plate 110 is in contact with an end portion 102 </ b> B of the air supply inlet 102 on a side far from the heating belt 62, and the current plate 110 extends in the first nip N <b> 6 direction in parallel with the sheet K conveyance path. It is arranged as follows. One end of the rectifying plate 110 on the side not in contact with the end 102B of the air supply inlet 102 is disposed closer to the first nip N6 than the end 102A of the air supply inlet 102 in the sheet K transport direction. . The width direction length of the current plate 110 is set to the same length as the width direction of the air supply inlet 102.
However, the position at which the current plate 110 is arranged and the shape of the current plate 110 are not limited to this, and may be any mode that forms an airflow that flows from the upstream end of the first nip N6 to the air supply inlet 102.

A hole 110A is provided in the current plate 110 so that air between the current plate 110 and the sheet K can flow into the air supply inlet 102 side. By providing holes 110 </ b> A in the current plate 110, it is possible to prevent the wind pressure between the current plate 110 and the sheet K from increasing due to the air current generated by the conveyance of the sheet K, and to disturb the unfixed toner image on the sheet K. Is easily suppressed.
The shape of the hole 110A provided in the current plate 110 is not particularly limited, and the shape of the current plate 110 in a plane facing the paper K transport direction is a circular shape, a streak shape extending in the paper K transport direction, and a paper K transport direction. It may be a streak shape or the like extending in a direction perpendicular to the direction. The number of the holes 110A is not particularly limited, and is freely set from the viewpoint of suppressing disturbance of the unfixed toner image.

The air outlet 104 has a shape parallel to the paper K transport path when viewed from the axial direction of the heating roll 32 and the pressure roll 34. It is arranged so as to face the paper K passing therethrough.
Since the air supply outlet 104 has a shape facing the sheet K, the UFP sent by the duct 100 can be easily attached to the sheet K.

  It should be noted that the vicinity of the transport path of the sheet K where the air supply outlet 104 is provided is defined as UFP contained in the air exhausted from the air supply outlet 104 toward the sheet K. It refers to the range up to a distance that can be attached to a region having no toner image on the K surface.

Here, the distance from each part of the air supply outlet 104 will be described.
The air supply outlet 104 is preferably installed at a distance of 10 mm or more and 40 mm or less (more preferably 10 mm or more and 30 mm or less) from the paper K transport path from the viewpoint of making the UFP easily adhere to the paper K.

It is preferable that the air supply outlet 104 is provided at a position where the sheet K can be exhausted after the sheet K is inserted into the second nip N3 and before the heated toner image is completely solidified. By exhausting the toner image before solidification, that is, the toner image which is still in a molten state, from the air supply outlet 104, the UFP can be easily attached to the toner image on the sheet K.
From this viewpoint, the distance in the paper K transport direction between the end 104A of the air supply outlet 104 on the side close to the heating roll 32 and the downstream end of the second nip N3 (that is, the distance between the downstream end of the second nip N3 and the paper The distance from the position corresponding to the end 104A on the K transport path is preferably 10 mm or more and 40 mm or less (more preferably, 10 mm or more and 30 mm or less).

  The end 104A of the air supply outlet 104 on the side close to the heating roll 32 is preferably installed at a distance of 10 mm or more and 40 mm or less (more preferably 10 mm or more and 30 mm or less) from the surface of the heating roll 32.

  Here, the operation of the duct 100 will be described.

  In the duct 100, fans 106 and 108 are rotated by a drive motor (not shown) to generate an air flow in the duct 100. Then, when the sheet K on which the unfixed toner image is formed on the surface passes through the first nip N6, the vaporized matter generated from the toner image, the recording medium, and the like, and floated upstream, The particles and the like generated by the solidification of the nitride again are taken in from the air supply inlet 102 together with the air around the upstream side of the first nip N6 as shown by an arrow U1. Then, the air taken in from the air supply inlet 102 is sent to the air supply outlet 104 and discharged by the airflow generated in the duct 100 by the fans 106 and 108 as shown by an arrow U2. The air discharged from the air supply outlet 104 reaches the paper K transport path as indicated by an arrow U3. Therefore, the UFP contained in the air discharged from the air supply outlet 104 adheres to a toner image on the sheet K, an area having no toner image on the surface of the sheet K, and the like. After that, the paper K to which the UFP has adhered is conveyed on the conveyance path and discharged out of the apparatus.

  The flow velocity (air supply speed) of the air moving in the duct 100 is not particularly limited, but is preferably set in accordance with the transport speed of the paper K. More specifically, the time required for the air entering through the air supply inlet 102 to be discharged from the air supply outlet 104 and reach the paper K conveyance path, and the time required for the paper K inserted through the upstream end of the first nip N6. It is preferable that the time until the air reaches the position where the air discharged from the air supply outlet 104 reaches is set to be synchronized. By setting as described above, the UFP generated from the toner image on the sheet K at the upstream end of the first nip N6 is replaced with the same sheet K (that is, the toner containing the release agent which is the source of the UFP). It is deposited on a sheet of paper K) having an image.

[Modified example of air pipe]
The shape, arrangement position, and the like of the air supply pipe are not limited to the aspect of the duct 100 shown in FIG.

For example, it is preferable to have means for heating the inside of the air supply pipe.
By heating the air inside the air supply pipe, the UFP passing through the air supply pipe is cooled and solidified, and is prevented from adhering to the inside of the air supply pipe. As a result, the coagulated UFP adhered to the inside of the air supply pipe becomes a larger lump, and is prevented from obstructing air supply.

Here, an embodiment provided with a means for heating the inside of the air supply pipe will be described with reference to the drawings.
FIG. 3 is a schematic configuration diagram showing a mode in which the duct 200 is arranged at a position close to the heating element 69 serving as a heating source of the heating belt 62 and the heating source 32D of the heating roll 32.
The heating belt 62, the pressure roll 61, the heating roll 32, and the pressure roll 34 illustrated in FIG. 3, the air supply inlet 202, the air supply outlet 204, the fans 206, 208, and the rectifying plate in the duct 200 Modes such as 210 are the same as those in FIG. 1 and detailed description is omitted here.

As shown in FIG. 3, the path of the duct 200 is directed from the air supply inlet 202 to a direction away from the transport path of the sheet K (that is, the upper side in FIG. 3), and then is bent at a right angle in the sheet transport direction, and The heating roll 32 passes through the opposite side of the paper K transport path (that is, the upper side of the heating belt 62 and the heating roll 32 in FIG. 3), and is further bent at a right angle in the transport path direction of the paper K. It is connected to an air supply outlet 204 provided. However, the duct 200 is arranged at a position near the heating belt 62 and a position near the heating roll 32 on the side opposite to the paper K transport path of the heating belt 62 and the heating roll 32 (that is, the upper side in FIG. 3). Have been.
Therefore, the duct 200 is heated by the heat from the heating element 69 inside the heating belt 62 and the heat from the heating source 32D inside the heating roll 32. This suppresses the UFP from solidifying and adhering to the inside of the duct 200, and further suppresses the adhering UFP coagulated material from forming a larger lump and hindering air supply.

The distance of the portion of the duct 200 closest to the heating belt 62 on the side opposite to the paper K transport path of the heating belt 62 (that is, the upper side in FIG. 3) is 10 mm or more and 50 mm or less (more preferably 10 mm or more and 30 mm or less). Preferably, there is.
The distance between the duct 200 and the side closest to the heating roll 32 on the side opposite to the paper K transport path of the heating roll 32 (that is, the upper side in FIG. 3) is 10 mm or more and 50 mm or less (more preferably 10 mm or more and 30 mm or less). Preferably, there is.

  Another embodiment provided with a means for heating the inside of the air supply pipe will be further described with reference to the drawings.

FIG. 4 is a schematic configuration diagram illustrating a mode in which a configuration is provided in which the warm air around the heating roll 32 is taken into the duct 300.
In addition, the form of the heating belt 62, the pressure roll 61, the heating roll 32, and the pressure roll 34 shown in FIG. 4, the air supply inlet 302, the air supply outlet 304, the fans 306, 308, and the rectifying plate in the duct 300 Embodiments such as 310 are the same as those in FIG. 1, and detailed description is omitted here.

As shown in FIG. 3, the path of the duct 300 is directed from the air inlet 302 to a direction away from the transport path of the sheet K (that is, the upper side in FIG. 3), and then is bent at a right angle in the sheet transport direction and the heating belt 62 and The heating roll 32 passes through the opposite side of the paper K transport path (that is, the upper side of the heating belt 62 and the heating roll 32 in FIG. 3), and is further bent at a right angle in the transport path direction of the paper K. It is connected to an air supply outlet 304 provided. However, a tube 318 having an air intake 314 is provided on the opposite side of the heating roll 32 from the paper K transport path (ie, above the heating roll 32 in FIG. 3). Then, the pipe 318 is connected to a position on the side of the duct 300 opposite to the sheet K transport path of the heating roll 32 (that is, above the heating roll 32 in FIG. 3). The tube 318 has a fan 316 inside, and air around the heating roll 32 is taken in from the air intake 314 and sent to the duct 300 through the inside of the tube 318.
Therefore, the air around the heating roll 32 warmed by the heat from the heating source 32D inside the heating roll 32 is taken into the duct 300 from the air intake port 314, and the inside of the duct 300 is heated. This suppresses the UFP from solidifying and adhering to the inside of the duct 300, and further suppresses the adhering UFP coagulated material from becoming a larger lump and hindering air supply.

The length in the width direction inside the pipe 318 (that is, the air flow path portion) is set to the same width direction length as the duct 300. However, it is set freely according to the amount of air taken in from around the heating roll 32.
The area of the cross section perpendicular to the air supply direction inside the pipe 318 (that is, the air flow path portion) is freely set according to the amount of air taken in from around the heating roll 32.

  The shortest distance of the air intake port 314 from the surface of the heating roll 32 is preferably 10 mm or more and 50 mm or less (more preferably 10 mm or more and 30 mm or less) from the viewpoint of facilitating heating of the inside of the duct 300.

[Coating member]
In the present embodiment, the configuration between the first fixing unit and the second fixing unit is not limited to the configuration shown in FIGS.
For example, it is preferable to provide a covering member that covers at least a part of the recording medium conveying surface between the first fixing unit and the second fixing unit.

Here, the UFP generated due to the vaporization of the release agent in the toner image is not generated only on the upstream side of the first nip in the first fixing unit. For example, although the generation amount is considered to be smaller than the upstream side of the first nip, the UFP may also occur downstream of the first nip.
On the other hand, by providing a covering member that covers at least a part of the surface of the recording medium having the toner image on the conveyance path of the recording medium between the first fixing unit and the second fixing unit, UFP is not generated. Suppressed or generated UFP is further suppressed from floating in the apparatus. As a result, the amount of UFP discharged outside the apparatus is reduced.

  Here, an embodiment provided with a covering member that covers at least a part of the recording medium conveying path between the first fixing unit and the second fixing unit on the side of the recording medium having the toner image will be described with reference to the drawings. explain.

FIG. 5 is a schematic configuration diagram showing an aspect including transport belts 42 and 44 for transporting the paper K while nipping and transporting the paper K from the first nip N6 to the second nip N3.
In addition, the form of the heating belt 62, the pressure roll 61, the heating roll 32, and the pressure roll 34 shown in FIG. 5, the duct 100, the air supply inlet 102, the air supply outlet 104, the fans 106, 108, and the rectifying plate Embodiments such as 110 are the same as those in FIG. 1, and detailed description is omitted here.

  The fixing device illustrated in FIG. 5 includes transport belts 42 and 44 that sandwich the sheet K inserted through the first nip N6 from both sides and transport the sheet K to the second nip N3. The transport belt 42 is in direct contact with the side of the sheet K having the toner image, and covers the side of the sheet K having the toner image. On the other hand, the transport belt 44 is in direct contact with the surface of the sheet K having no toner image. The transport belt 42 is stretched over the rolls 46A and 46B. At least one of the rolls 46A and 46B is a drive roll for rotating and driving the transport belt 42. The transport belt 44 is stretched over the rolls 48A and 48B. At least one of the rolls 48A and 48B is a drive roll for rotating the transport belt 44.

  As described above, in the transport path of the paper K between the first nip N6 and the second nip N3, the transport belt 42 that covers the surface of the paper K having the toner image so as to be in direct contact with the paper K is provided. Floating of the vapor of the mold agent out of the toner image is suppressed. Therefore, it is considered that the vaporized product of the release agent is prevented from floating in the air, cooled and solidified, that is, the generation of UFP is suppressed.

The length in the paper K transport direction of the region where the transport belt 42 is in direct contact with the paper K is from the downstream end of the first nip N6 to the upstream end of the second nip N3 from the viewpoint of suppressing the generation of UFP. The length is preferably 90% or more, more preferably 95% or more, with respect to the length.
Note that the upper limit of the length of the area where the transport belt 42 is in direct contact with the sheet K is the positional relationship between the heating belt 62 and the heating roll 32 and the transport belt 42, The transport belts 42 and 44 are determined within a settable range according to the positional relationship with the belt 44 and the like.

  The length in the width direction of the transport belts 42 and 44 is set longer than the length in the width direction of the paper K.

  As a configuration of the transport belts 42 and 44, for example, a belt having a configuration used for the above-described heating belt 62 is preferably used.

  FIG. 4 is a diagram showing another embodiment in which a covering member that covers at least a part of the recording medium conveying surface between the first fixing unit and the second fixing unit on the side of the recording medium having the toner image is provided. It will be described using FIG.

FIG. 6 is a schematic configuration diagram showing an aspect including a cover plate 52 that covers the surface of the sheet K having the toner image away from the sheet K between the first nip N6 and the second nip N3.
In addition, the form of the heating belt 62, the pressure roll 61, the heating roll 32, and the pressure roll 34 shown in FIG. 6, the duct 100, the air supply inlet 102, the air supply outlet 104, the fans 106, 108, and the rectifying plate Embodiments such as 110 are the same as those in FIG. 1, and detailed description is omitted here.

The fixing device illustrated in FIG. 6 includes a cover plate 52 that covers the surface of the sheet K having the toner image, which has been inserted through the first nip N6, away from the sheet K.
As described above, in the transport path of the sheet K between the first nip N6 and the second nip N3, the cover plate 52 that covers the surface of the sheet K having the toner image away from the first nip N6 is provided. Even when the UFP is generated from the toner image on the paper K after the insertion, the UFP is prevented from floating in the apparatus by the cover plate 52. It is considered that most of the UFP whose floating is suppressed by the covering plate 52 adheres again to a region where the toner image or the paper K has no toner image. As a result, the amount of UFP discharged outside the apparatus is reduced.

The length of the area where the sheet K is covered by the cover plate 52 in the sheet K transport direction is from the downstream end of the first nip N6 to the upstream side of the second nip N3 from the viewpoint of suppressing the discharge amount of the UFP to the outside of the apparatus. It is preferably at least 80%, more preferably at least 90%, of the length up to the terminal.
The upper limit of the length of the area where the sheet K is covered by the cover plate 52 is within a range in which the cover plate 52 can be installed according to the positional relationship between the heating belt 62 and the heating roll 32 and the cover plate 52, and the like. It is determined.

  The length in the width direction of the cover plate 52 is set to be longer than the length in the width direction of the paper K.

  The material of the cover plate 52 is not particularly limited. Note that a material having heat resistance is preferably used, and for example, a metal plate, a resin plate, or the like is preferably used.

  As described above, the embodiments of the fixing device and the air supply pipe according to the present embodiment have been described with reference to FIGS. 2 to 6. However, the present invention is not limited to these embodiments. It goes without saying that the configuration and the like can be freely changed.

(Developer)
Next, in the image forming apparatus according to the present embodiment, the toner of the developer contained in the developing unit will be described in detail.

  Hereinafter, details of the toner according to the exemplary embodiment will be described.

  The toner according to the exemplary embodiment includes toner particles and, as necessary, an external additive.

(Toner particles)
The toner particles include, for example, a binder resin, a release agent, and, if necessary, a colorant and other additives.

-Release agent-
The melting temperature of the release agent is from 60 ° C to 100 ° C, preferably from 60 ° C to 90 ° C, more preferably from 60 ° C to 75 ° C.
When the melting temperature of the release agent is 100 ° C. or lower, the low-temperature fixing property of the toner is improved, and thus the fixing temperature in the image forming apparatus can be reduced. However, if the melting temperature of the release agent is 100 ° C. or lower, the release agent is likely to be vaporized during fixing of the toner, and the vaporized release agent is likely to coagulate again in the air, thereby generating UFP. However, even in such a case, according to the present embodiment, the amount of UFP discharged to the outside of the image forming apparatus is reduced.
On the other hand, when the melting temperature of the release agent is 60 ° C. or higher, the release agent is prevented from adhering to the fixing member due to excessive melting of the release agent during fixing of the toner. Further, it is possible to suppress the occurrence of excessive UFP.
The melting temperature of the release agent is controlled by a known method such as selection of the type of the release agent.

  The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) according to the “melting peak temperature” described in JIS K 7121-1987 “Method for measuring the transition temperature of plastics”. .

The release agent is not particularly limited. For example, mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax; polyethylene wax, polypropylene wax, and polybutene wax Hydrocarbon waxes such as silicone waxes; fatty acid amide waxes such as oleic acid amide wax, erucic acid amide wax, ricinoleic acid amide wax, stearic acid amide wax; carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil Vegetable wax such as beeswax; animal wax such as beeswax; ester wax such as fatty acid ester, montanic acid ester and carboxylic acid ester; and modified products thereof. That.
Among these, paraffin wax, ceresin, carnauba wax, fatty acid ester, and montanic acid ester are preferable, and paraffin wax is more preferable, from the viewpoint of the low-temperature fixability of the toner.

  The release agent may be used alone or in combination of two or more. When two or more types are used in combination, it is preferable that the melting temperature of at least one type of the release agent is in the above-mentioned range, and further, the melting temperature of all the included release agents is in the above-mentioned range.

  The content of the release agent is, for example, preferably from 1% by mass to 20% by mass, more preferably from 5% by mass to 15% by mass, based on the whole toner particles.

The melting temperature of the release agent and the set fixing temperature The melting temperature [T2] of the release agent is different from the set fixing temperature [T1] of the first rotating body pair of the image forming apparatus by the difference [T1-T2]. ] Is preferably from 40 ° C to 120 ° C, more preferably from 50 ° C to 110 ° C, even more preferably from 60 ° C to 100 ° C.
When the set fixing temperature [T1] is higher than the melting temperature [T2] of the release agent and the difference [T1−T2] is 120 ° C. or less, the fixing temperature in the image forming apparatus can be reduced. On the other hand, when the difference [T1−T2] is equal to or higher than 40 ° C., the adhesion of the toner to the fixing member during the fixing of the toner can be suppressed.
However, if the difference [T1−T2] exceeds 120 ° C., the release agent is liable to vaporize when the toner is fixed, and the vaporized release agent is likely to solidify again in the air, thereby generating UFP. However, even in that case, according to the present embodiment, the amount of UFP discharged to the outside of the apparatus is reduced.

-Binder resin-
Examples of the binder resin include styrenes (eg, styrene, parachlorostyrene, α-methylstyrene, etc.) and (meth) acrylates (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid) n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc., ethylenically unsaturated nitriles (for example, acrylonitrile, Methacrylonitrile, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene Emissions, a homopolymer of a monomer such as butadiene) and the like, or a vinyl-based resin composed of these monomers with two or more combinations copolymer.
As the binder resin, for example, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, a non-vinyl resin such as a modified rosin, a mixture of these and the vinyl resin, or a mixture thereof. A graft polymer obtained by polymerizing a vinyl monomer in the coexistence is also included.
One of these binder resins may be used alone, or two or more thereof may be used in combination.

  From the viewpoint of improving the low-temperature fixability of the toner, it is preferable that a crystalline resin is included as the binder resin.

As the binder resin, a polyester resin is preferable. As the binder resin, a crystalline polyester is preferable.
Examples of the polyester resin include a known amorphous polyester resin. As the polyester resin, a crystalline polyester resin may be used together with the amorphous polyester resin.

Note that the “crystallinity” of the resin refers to having a distinct endothermic peak, not a stepwise endothermic change in differential scanning calorimetry (DSC), and specifically, a temperature increase rate of 10 (° C.) / Min) means that the half width of the endothermic peak is within 10 ° C.
On the other hand, “amorphous” of the resin indicates that the half-value width exceeds 10 ° C., that the resin exhibits a stepwise change in endothermic amount, or that no clear endothermic peak is observed.

-Amorphous polyester resin Examples of the amorphous polyester resin include a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product or a synthesized product may be used.

Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.) Alicyclic dicarboxylic acid (eg, cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acid (eg, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), anhydrides thereof, or lower (eg, having 1 or more carbon atoms) 5 or less) alkyl esters. Among these, as the polyvalent carboxylic acid, for example, an aromatic dicarboxylic acid is preferable.
The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid and a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, having 1 to 5 carbon atoms) alkyl esters thereof.
Polycarboxylic acids may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include aliphatic diols (eg, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.) and alicyclic diols (eg, cyclohexanediol, cyclohexanedimethanol, Hydrogenated bisphenol A, etc.) and aromatic diols (eg, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, etc.). Among these, as the polyhydric alcohol, for example, an aromatic diol and an alicyclic diol are preferable, and an aromatic diol is more preferable.
As the polyhydric alcohol, a tri- or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
Polyhydric alcohols may be used alone or in combination of two or more.

The glass transition temperature (Tg) of the amorphous polyester resin is preferably from 50 ° C to 80 ° C, more preferably from 50 ° C to 65 ° C.
In addition, the glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, described in JIS K 7121-1987 “Method for measuring glass transition temperature” in “Method of measuring glass transition temperature”. Of "extrapolated glass transition onset temperature".

The weight average molecular weight (Mw) of the amorphous polyester resin is preferably from 5,000 to 1,000,000, more preferably from 7000 to 500,000.
The number average molecular weight (Mn) of the amorphous polyester resin is preferably from 2,000 to 100,000.
The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably from 1.5 to 100, more preferably from 2 to 60.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed using a Tosoh column and TSKgel Super HM-M (15 cm) using a Tosoh GPC / HLC-8120GPC as a measuring device, using a THF solvent. The weight average molecular weight and the number average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

The amorphous polyester resin can be obtained by a well-known manufacturing method. Specifically, for example, it can be obtained by a method in which the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure in the reaction system is reduced as necessary, and the reaction is carried out while removing water and alcohol generated during condensation.
When the raw material monomers are not dissolved or compatible at the reaction temperature, a high boiling point solvent may be added as a solubilizing agent to dissolve the monomers. In this case, the polycondensation reaction is performed while distilling off the dissolution aid. If a monomer having poor compatibility exists in the copolymerization reaction, the monomer having poor compatibility and the monomer or acid or alcohol to be polycondensed are condensed in advance, and then polymerized together with the main component. It is good to condense.

-Crystalline polyester resin The crystalline polyester resin includes, for example, a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the crystalline polyester resin, a commercially available product may be used, or a synthesized product may be used.
Here, in order to easily form a crystalline structure, the crystalline polyester resin is preferably a polycondensate using a polymerizable monomer having a straight-chain aliphatic group rather than a polymerizable monomer having an aromatic group.

Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid) Acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acid (for example, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid) Dibasic acids such as acids), anhydrides thereof, and lower (e.g., 1 to 5 carbon atoms) alkyl esters thereof.
The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid and a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (eg, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.) Anhydrides and lower (e.g., 1 to 5 carbon atoms) alkyl esters thereof are exemplified.
As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.
Polycarboxylic acids may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include an aliphatic diol (for example, a linear aliphatic diol having a carbon number of 7 to 20 in a main chain portion). Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Octadecanediol, 1,14-eicosandecanediol and the like can be mentioned. Among them, as the aliphatic diol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable.
As the polyhydric alcohol, a tri- or higher-valent alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.
Polyhydric alcohols may be used alone or in combination of two or more.

  Here, the polyhydric alcohol may have an aliphatic diol content of at least 80 mol%, preferably at least 90 mol%.

The melting temperature of the crystalline polyester resin is preferably from 50 ° C to 100 ° C, more preferably from 55 ° C to 90 ° C, and still more preferably from 60 ° C to 85 ° C.
The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) according to the “melting peak temperature” described in JIS K7121-1987 “Method of measuring the melting temperature of plastics”.

  The weight average molecular weight (Mw) of the crystalline polyester resin is preferably from 6,000 to 35,000.

  The crystalline polyester resin is obtained by a well-known manufacturing method, for example, similarly to the amorphous polyester resin.

  The content of the binder resin is, for example, preferably from 40% by mass to 95% by mass, more preferably from 50% by mass to 90% by mass, and more preferably from 60% by mass to 85% by mass, based on the whole toner particles. More preferred.

  In addition, the content of the crystalline resin is preferably 3% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 15% by mass or less based on the whole toner particles, from the viewpoint of enhancing the low-temperature fixability of the toner. .

-Coloring agent-
Examples of the coloring agent include carbon black, chrome yellow, Hansa yellow, benzidine yellow, slen yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmine 6B, Dupont Oil Red, Pyrazolone Red, Lisor Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, or acridine, xanthene, Various dyes such as benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole And the like.
One type of colorant may be used alone, or two or more types may be used in combination.

  The colorant may be a surface-treated colorant as necessary, or may be used in combination with a dispersant. In addition, a plurality of colorants may be used in combination.

  The content of the colorant is, for example, preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the whole toner particles.

-Other additives-
Examples of the other additives include well-known additives such as a magnetic substance, a charge control agent, and an inorganic powder. These additives are contained in the toner particles as internal additives.

-Characteristics of toner particles-
The toner particles may be toner particles having a single-layer structure, or toner particles having a so-called core-shell structure composed of a core material (core particles) and a coating layer (shell layer) covering the core material. You may.
Here, the toner particles having a core-shell structure include, for example, a core material including a binder resin and other additives such as a colorant and a release agent as needed, and a binder resin. And a coating layer configured.

  The volume average particle diameter (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, more preferably 4 μm or more and 8 μm or less.

Various average particle diameters and various particle size distribution indexes of the toner particles were measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolytic solution was measured using ISOTON-II (manufactured by Beckman Coulter). You.
In the measurement, 0.5 mg or more and 50 mg or less of a measurement sample are added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant. This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolyte in which the sample is suspended is subjected to dispersion treatment for 1 minute by an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm to 60 μm is measured using a Coulter Multisizer II using an aperture having an aperture diameter of 100 μm. Measure. The number of particles to be sampled is 50,000.
A volume distribution and a number are plotted from the smaller diameter side for the particle size range (channel) divided based on the measured particle size distribution, and the particle size at which the accumulation becomes 16% is determined as the volume particle size D16v and the number particle size. D16p, the particle diameter at which the accumulation is 50% is defined as a volume average particle diameter D50v, the accumulation number average particle diameter D50p, and the particle diameter at which the accumulation is 84% are defined as volume particle diameter D84v and number particle diameter D84p.
Using these, the volume particle size distribution index (GSDv) is calculated as (D84v / D16v) ^1/2 , and the number particle size distribution index (GSDp) is calculated as (D84p / D16p) ^1/2 .

The shape factor SF1 of the toner particles is preferably from 140 to 155, more preferably from 143 to 153, even more preferably from 145 to 151.
Here, when the toner particles are produced by a pulverizing method such as a kneading and pulverizing method, the shape is irregular, and for example, the shape factor SF1 is 140 or more. In the case of toner particles having a shape factor SF1 of 140 or more, the release agent is likely to be exposed on the surface due to the manufacturing method. The release agent exposed on the surface is easily vaporized by heat when fixing the toner, and as a result, UFP is easily generated. However, even in such a case, according to the present embodiment, the amount of UFP discharged to the outside of the image forming apparatus is reduced.

The shape factor SF1 is obtained by the following equation.
Formula: SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML indicates the absolute maximum length of the toner, and A indicates the projected area of the toner.
Specifically, the shape factor SF1 is quantified by mainly analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and is calculated as follows. That is, the optical microscope image of the particles scattered on the slide glass surface is taken into a Luzex image analyzer by a video camera, the maximum length and the projected area of 100 particles are obtained, calculated by the above equation, and the average value thereof is obtained. can get.

The toluene-insoluble content of the toner particles is preferably from 25% by mass to 40% by mass, more preferably from 28% by mass to 38% by mass, and still more preferably from 30% by mass to 35% by mass.
When the toluene insoluble content of the toner particles is in the above range, the release agent is confined in the toner particles, and the exposure of the release agent to the surface is suppressed. As a result, generation of UFP due to the release agent is suppressed.

  Here, the toluene-insoluble portion of the toner particles is a component of the toner particles that are insoluble in toluene. That is, the toluene-insoluble component is an insoluble component containing a binder resin component (particularly, a high molecular weight component of the binder resin) insoluble in toluene as a main component (for example, 50% by mass or more of the whole). This toluene-insoluble content can be said to be an index of the content of the crosslinked resin contained in the toner.

The toluene-insoluble content is a value measured by the following method.
1 g of the weighed toner particles (or toner) is put into the weighed glass fiber cylindrical filter paper, and is attached to an extraction tube of a heated Soxhlet extraction device. Then, toluene is injected into the flask and heated to 110 ° C. using a mantle heater. In addition, the periphery of the extraction tube is heated to 125 ° C. using a heating heater attached to the extraction tube. Extraction is performed at a reflux rate such that the extraction cycle is performed once within a range of 4 minutes to 5 minutes. After extraction for 10 hours, the cylindrical filter paper and the toner residue are taken out, dried, and weighed.
Then, the formula: toner particle (or toner) residue amount (mass%) = [(cylinder filter paper amount + toner residue amount) (g) -cylinder filter paper amount (g)] ÷ toner particle (or toner) mass (g) × Based on 100, the residual amount (% by mass) of the toner particles (or toner) is calculated, and the residual amount (% by mass) of the toner particles (or toner) is defined as a toluene-insoluble content (% by mass).
The toner particle (or toner) residue is composed of an inorganic substance such as a colorant and an external additive, and a high molecular weight component of a binder resin. Further, when the toner particles contain a release agent, extraction by heating is performed, so that the release agent is a toluene-soluble component.

  The toluene-insoluble content of the toner particles may be, for example, a method of forming a crosslinked structure or a branched structure by adding a crosslinking agent to a polymer component having a reactive functional group at the terminal, and 2) at the terminal of the binder resin. It is adjusted by a method of forming a crosslinked structure or a branched structure with a polyvalent metal ion in a polymer component having an ionic functional group, 3) a method of elongating a resin chain length by treatment with an isocyanate or the like, or a method of forming a branch.

(External additives)
Examples of the external additive include inorganic particles. As the inorganic particles, SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO. SiO ₂ , K ₂ O. (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like.

The surface of the inorganic particles as an external additive is preferably subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include a silane coupling agent, a silicone oil, a titanate coupling agent, and an aluminum coupling agent. These may be used alone or in combination of two or more.
The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less based on 100 parts by mass of the inorganic particles.

  Examples of the external additive include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), a cleaning activator (for example, a metal salt of a higher fatty acid represented by zinc stearate, a fluoropolymer, Particles).

  The external additive amount of the external additive is, for example, preferably from 0.01% by mass to 5% by mass, more preferably from 0.01% by mass to 2.0% by mass, based on the toner particles.

(Method of manufacturing toner)
Next, a method for manufacturing a toner according to the exemplary embodiment will be described.
The toner according to the exemplary embodiment is obtained by externally adding an external additive to the toner particles after manufacturing the toner particles.

The toner particles may be manufactured by any of a dry manufacturing method (for example, a kneading and pulverizing method) and a wet manufacturing method (for example, an aggregation and coalescence method, a suspension polymerization method, and a dissolution suspension method). The production method of the toner particles is not particularly limited, and a known production method is employed.
Among these, it is preferable to obtain the toner particles by the aggregation and coalescence method.

-Aggregation coalescence method Specifically, for example, when the toner particles are manufactured by the aggregation coalescence method,
A step of preparing a resin particle dispersion in which resin particles serving as a binder resin are dispersed (resin particle dispersion preparation step); and a step of mixing a resin particle dispersion in the resin particle dispersion (if necessary, (In the dispersion), aggregating the resin particles (other particles as necessary) to form aggregated particles (aggregated particle forming step), and heating the aggregated particle dispersion in which the aggregated particles are dispersed. And a step of fusing and coalescing the aggregated particles to form toner particles (fusing / coalescing step), thereby producing toner particles.

Hereinafter, details of each step will be described.
In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described, but the colorant and the release agent are used as needed. Of course, other additives other than the colorant and the release agent may be used.

-Resin particle dispersion preparation process-
First, together with a resin particle dispersion in which resin particles serving as a binder resin are dispersed, for example, a colorant particle dispersion in which colorant particles are dispersed, and a release agent particle dispersion in which release agent particles are dispersed are prepared. I do.

  Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

Examples of the dispersion medium used for the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion-exchanged water, and alcohols. These may be used alone or in combination of two or more.

Examples of the surfactant include anionic surfactants such as sulfate ester type, sulfonate type, phosphate ester type and soap type; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And non-ionic surfactants such as alkylphenol ethylene oxide adducts and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
One type of surfactant may be used alone, or two or more types may be used in combination.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion include general dispersion methods such as a rotary shearing homogenizer, a ball mill having a medium, a sand mill, and a dyno mill. Depending on the type of the resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method.
The phase inversion emulsification method is a method in which a resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to an organic continuous phase (O phase) for neutralization. (W phase), a method of converting the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase, and dispersing the resin in an aqueous medium in a particulate form. It is.

The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, further preferably 0.1 μm or more and 0.6 μm or less. preferable.
The volume average particle size of the resin particles is determined by using a particle size distribution obtained by measurement using a laser diffraction type particle size distribution measuring device (for example, LA-700, manufactured by HORIBA, Ltd.). The volume-average particle size D50v is measured by subtracting the cumulative distribution from the small particle size side with respect to the volume and determining the particle size at which 50% of the total particles are accumulated. In addition, the volume average particle diameter of the particles in other dispersion liquids is measured similarly.

  The content of the resin particles contained in the resin particle dispersion is, for example, preferably from 5% by mass to 50% by mass, and more preferably from 10% by mass to 40% by mass.

  In the same manner as the resin particle dispersion, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared. In other words, regarding the volume average particle diameter of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the content of the particles, the colorant particles dispersed in the colorant particle dispersion, and the release agent particle dispersion The same applies to the releasing agent particles to be dispersed.

-Aggregated particle formation process-
Next, the colorant particle dispersion and the release agent particle dispersion are mixed together with the resin particle dispersion.
Then, in the mixed dispersion, the resin particles, the colorant particles, and the release agent particles having a diameter close to the diameter of the intended toner particles by hetero-aggregating the resin particles, the colorant particles, and the release agent particles, To form aggregated particles.

Specifically, for example, after adding a flocculant to the mixed dispersion, adjusting the pH of the mixed dispersion to acidic (for example, pH of 2 or more and 5 or less), and adding a dispersion stabilizer as necessary, Heating to a temperature of the glass transition temperature of the resin particles (specifically, for example, the glass transition temperature of the resin particles −30 ° C. or more and the glass transition temperature of −10 ° C. or less) to aggregate the particles dispersed in the mixed dispersion. Form aggregated particles.
In the aggregated particle forming step, for example, the above-mentioned aggregating agent is added at room temperature (for example, 25 ° C.) while stirring the mixed dispersion with a rotary shearing homogenizer, and the pH of the mixed dispersion is made acidic (for example, when the pH is 2 or more and 5 or less). ), And the above-mentioned heating may be performed after adding a dispersion stabilizer as needed.

Examples of the coagulant include a surfactant having a polarity opposite to that of the surfactant used as a dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher valent metal complex. In particular, when a metal complex is used as the aggregating agent, the amount of the surfactant used is reduced, and the charging characteristics are improved.
If necessary, an additive that forms a complex or a similar bond with the metal ion of the flocculant may be used. As this additive, a chelating agent is suitably used.

Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic salts such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. And metal salt polymers.
As the chelating agent, a water-soluble chelating agent may be used. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid and gluconic acid, iminodiic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).
The addition amount of the chelating agent is, for example, preferably from 0.01 to 5.0 parts by mass, more preferably from 0.1 to less than 3.0 parts by mass, per 100 parts by mass of the resin particles.

-Fusion and coalescence process-
Next, the aggregated particle dispersion in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (e.g., equal to or higher than 10 to 30 ° C. higher than the glass transition temperature of the resin particles). To form toner particles.

Through the above steps, toner particles are obtained.
In addition, after obtaining the aggregated particle dispersion in which the aggregated particles are dispersed, the aggregated particle dispersion and the resin particle dispersion in which the resin particles are dispersed are further mixed, and the resin particles are further mixed on the surface of the aggregated particles. Aggregating so as to adhere to form second aggregated particles, and heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and unite the second aggregated particles. And forming a toner particle having a core / shell structure.

Here, after completion of the fusion / coalescing step, the toner particles formed in the solution are subjected to a known washing step, solid-liquid separation step, and drying step to obtain dried toner particles.
In the washing step, it is preferable to sufficiently perform replacement washing with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but is preferably performed by suction filtration, pressure filtration, or the like from the viewpoint of productivity. The drying step is not particularly limited, but freeze-drying, flash drying, fluidized drying, vibration-type fluidized drying, and the like are preferably performed from the viewpoint of productivity.

  The toner according to the exemplary embodiment is manufactured by, for example, adding an external additive to the obtained toner particles in a dry state and mixing. The mixing may be performed by, for example, a V blender, a Henschel mixer, a Loedige mixer, or the like. Further, if necessary, coarse particles of the toner may be removed using a vibration sieving machine, a wind sieving machine, or the like.

-Kneading and crushing method The toner particles in the present embodiment may be produced by a crushing method such as a kneading and crushing method. When manufactured by a pulverization method, the shape is irregular, and for example, the shape factor SF1 is in the above-described range. Then, since the release agent is easily exposed on the surface due to the manufacturing method, UFP is easily generated. However, even in that case, according to the present embodiment, the amount of UFP discharged to the outside of the apparatus is reduced.

The kneading and pulverizing method is a method for producing toner particles by melt-kneading a binder resin and a release agent containing at least a specific paraffin-based wax having a melting temperature in the above-described range, followed by pulverization and classification. . In the kneading and pulverizing method, for example, a kneading step of melt-kneading components including a binder resin and a release agent, a cooling step of cooling the melt-kneaded material, a pulverizing step of pulverizing the kneaded material after cooling, and a pulverized material And a classification step of classifying the toner particles to produce toner particles.
Hereinafter, the details of each step of the kneading and pulverizing method will be described.

-Kneading process-
The kneading step is a step of melt-kneading constituent components (resin particle forming material) containing a binder resin and a release agent to obtain a kneaded product.
Examples of the kneading machine used in the kneading step include a three-roll type, a single screw type, a twin screw type, and a Banbury mixer type.
Further, the melting temperature may be determined according to the types and the mixing ratios of the binder resin and the release agent to be kneaded.

-Cooling process-
The cooling step is a step of cooling the kneaded material formed in the kneading step.
In the cooling step, in order to maintain a dispersed state immediately after the completion of the kneading step, it is preferable to cool the kneaded material at the end of the kneading step to 40 ° C. or lower at an average temperature lowering rate of 4 ° C./sec or more.
In addition, the average cooling rate refers to the average value of the rate at which the temperature of the kneaded material is lowered from the temperature of the kneaded material to 40 ° C. at the end of the kneading step.

  As a cooling method in the cooling step, for example, a method using a rolling roll circulating cold water or brine, a sandwiching-type cooling belt, or the like can be used. When the cooling is performed by the above method, the cooling rate is determined by the speed of the rolling roll, the flow rate of the brine, the supply amount of the kneaded material, the slab thickness at the time of rolling the kneaded material, and the like. The slab thickness is preferably 1 mm or more and 3 mm or less.

-Pulverizing process-
Particles are formed by pulverizing the kneaded material cooled in the cooling step in the pulverizing step.
In the pulverizing step, for example, a mechanical pulverizer, a jet pulverizer, or the like is used.

-Classification process-
The pulverized product (particles) obtained in the pulverizing step may be subjected to classification in a classification step, if necessary.
In the classification process, a conventionally used centrifugal classifier, inertial classifier, or the like is used, and fine powder (particles smaller than the target range) and coarse powder (particles in the target range) are used. Larger particles) are removed.

  The toner according to the exemplary embodiment is manufactured by, for example, adding an external additive to the obtained toner particles in a dry state and mixing. The mixing may be performed by, for example, a V blender, a Henschel mixer, a Lodige mixer, or the like. Further, if necessary, coarse particles of the toner may be removed using a vibration sieving machine, a wind sieving machine, or the like.

(Developer)
The developer according to the embodiment includes at least the toner according to the embodiment.
The developer in the present embodiment may be a one-component developer containing only the toner in the present embodiment, or a two-component developer in which the toner and a carrier are mixed.

The carrier is not particularly limited, and includes known carriers. Examples of the carrier include a coated carrier in which a core resin made of a magnetic powder is coated with a coating resin; a magnetic powder-dispersed carrier in which a magnetic powder is dispersed and blended in a matrix resin; a porous magnetic powder impregnated with a resin; And a resin-impregnated carrier.
Note that the magnetic powder-dispersed carrier and the resin-impregnated carrier may be a carrier in which constituent particles of the carrier are used as a core material and the core material is coated with a coating resin.

  Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

Examples of the coating resin and the matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, and styrene-acrylate. Examples thereof include a copolymer, a straight silicone resin containing an organosiloxane bond or a modified product thereof, a fluororesin, a polyester, a polycarbonate, a phenol resin, and an epoxy resin.
Note that the coating resin and the matrix resin may contain other additives such as conductive particles.
Examples of the conductive particles include particles such as metals such as gold, silver and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

Here, in order to coat the surface of the core material with the coating resin, a method of coating the coating resin with a coating layer forming solution in which various additives are dissolved in an appropriate solvent, if necessary, and the like can be mentioned. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, suitability for application, and the like.
Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming the coating layer, a spray method in which the solution for forming the coating layer is sprayed on the surface of the core material, and a method in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed, and a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater to remove a solvent.

  The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner: carrier = 1: 100 to 30: 100, and more preferably 3: 100 to 20: 100.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following, “parts” are based on mass unless otherwise specified.

<Preparation of crystalline resin (A)>
First, 100 parts of dimethyl sebacate, 67.8 parts of hexanediol, and 0.10 part of dibutyltin oxide are placed in a three-necked flask, and water generated during the reaction is removed outside the system under a nitrogen atmosphere. After the reaction at 185 ° C. for 5 hours, the temperature was increased to 220 ° C. while gradually reducing the pressure, and the reaction was continued for 6 hours, followed by cooling. Thus, a crystalline resin (A) having a weight average molecular weight of 33,700 was prepared.

<Preparation of amorphous resin>
(Preparation of amorphous resin (1))
In a three-necked flask, 61 parts of dimethyl terephthalate, 75 parts of dimethyl fumarate, 34 parts of dodecenylsuccinic anhydride, 16 parts of trimellitic acid, 137 parts of an adduct of bisphenol A ethylene oxide, and 137 parts of bisphenol A propylene oxide were added. 191 parts of the product and 0.3 parts of dibutyltin oxide were added, and the mixture was reacted at 180 ° C. for 3 hours while removing water generated by the reaction under a nitrogen atmosphere, and then gradually reduced in pressure. The temperature was raised to 280 ° C., and after reacting for 2 hours, the mixture was cooled. Thus, an amorphous resin (1) having a weight average molecular weight of 19000 was prepared.

(Preparation of amorphous resin (2))
Except that 60 parts of dimethyl terephthalate, 74 parts of dimethyl fumarate, 30 parts of dodecenylsuccinic anhydride, and 22 parts of trimellitic acid were used, the same procedure as in the preparation of the amorphous resin (1) was applied to the amorphous resin (2). Was prepared. The weight average molecular weight of the amorphous resin (2) was 19,500.

(Preparation of amorphous resin (3))
Except that 60 parts of dimethyl terephthalate, 70 parts of dimethyl fumarate, 29 parts of dodecenylsuccinic anhydride and 29 parts of trimellitic acid were used, the same procedure as in the preparation of the amorphous resin (1) was applied to the amorphous resin (3). Was prepared. The weight average molecular weight of the amorphous resin (3) was 18,200.

(Preparation of amorphous resin (4))
Except that 55 parts of dimethyl terephthalate, 64 parts of dimethyl fumarate, 27 parts of dodecenyl succinic anhydride, and 46 parts of trimellitic acid were used, the same procedure as in the preparation of the amorphous resin (1) was carried out. Was prepared. The weight average molecular weight of the amorphous resin (3) was 17,200.

<Preparation of toner>
(Production of toner particles (1))
79 parts of the amorphous resin (1), 7 parts of a colorant (CI Pigment Blue 15: 1), and 5 parts of a release agent (paraffin wax, a melting temperature of 73 ° C., manufactured by Nippon Seiro Co., Ltd.) , And 8 parts of the crystalline resin (A) (melting temperature: 71 ° C.) were charged into a Henschel mixer (manufactured by Nippon Coke Industry Co., Ltd.) and stirred and mixed at a peripheral speed of 15 m / sec for 5 minutes. Was melt-kneaded with an extruder-type continuous kneader.
Here, the setting conditions of the extruder were as follows: the supply side temperature was 160 ° C., the discharge side temperature was 130 ° C., the supply side temperature of the cooling roll was 40 ° C., and the discharge side temperature was 25 ° C. In addition, the temperature of the cooling belt was set to 10 ° C.
After cooling the obtained melt-kneaded material, it was roughly pulverized using a hammer mill, and then finely pulverized to 6.5 μm using a jet pulverizer (manufactured by Nippon Pneumatic Industrial Co., Ltd.), and further, an elbow jet classifier. (Model: EJ-LABO, manufactured by Nippon Steel Mining Co., Ltd.) to obtain toner particles (1) having a volume average particle diameter of 6.9 μm.
The shape factor SF1 of the toner particle (1) was 145, and the toluene-insoluble content was 25% by mass.

(Production of toner particles (2))
A toner particle (2) having a volume average particle diameter of 6.8 μm was obtained in the same manner as in the preparation of the toner (1) except that the amorphous resin (2) was used instead of the amorphous resin (1). .
The shape factor SF1 of the toner particles (2) was 147, and the toluene-insoluble content was 29% by mass.

(Production of Toner Particles (3))
Toner particles (3) having a volume average particle diameter of 7.0 μm were obtained in the same manner as in the preparation of toner (1) except that amorphous resin (3) was used instead of amorphous resin (1).
The shape factor SF1 of the toner particles (3) was 149, and the toluene-insoluble content was 35% by mass.

(Production of Toner Particles (4))
Toner particles (4) having a volume average particle diameter of 7.3 μm were obtained in the same manner as in the preparation of toner (1) except that amorphous resin (4) was used instead of amorphous resin (1).
The shape factor SF1 of the toner particles (4) was 151, and the toluene-insoluble content was 40% by mass.

(Production of Toner Particles (5))
Toner particles (5) having a volume average particle diameter of 6.8 μm were obtained in the same manner as in the preparation of toner (1), except that ceresin wax (melting temperature: 92 ° C.) was used as a release agent.
The shape factor SF1 of the toner particles (5) was 148, and the toluene-insoluble content was 33% by mass.

(Preparation of Toner Particle (C1))
Except that paraffin wax (manufactured by Baker Petrolite: polywax 725, melting temperature 105 ° C.) was used as the release agent, toner particles (C1 ) Got.
The shape factor SF1 of the toner particles (C1) was 146, and the toluene-insoluble content was 45% by mass.

(Production of toner and developer)
Using a Henschel mixer (manufactured by Mitsui Miike Seisakusho), 100 parts of each toner particle and 1.2 parts of commercially available fumed silica RX50 (manufactured by Nippon Aerosil) as an external additive were used at a peripheral speed of 30 m / s for 5 minutes. Under the conditions, toners (1) to (5) and (C1) were obtained.
Subsequently, 8 parts of each of the obtained toners and 100 parts of the carrier were mixed to prepare developers (1) to (5) and (C1), respectively.
The carrier was 100 parts of ferrite particles (volume average particle size: 50 μm), 14 parts of toluene, and a styrene-methyl methacrylate copolymer (component ratio: styrene / methyl methacrylate = 90/10, weight average molecular weight Mw = 80000). 2) was prepared by first dispersing the above components except for the ferrite particles by stirring with a stirrer for 10 minutes to prepare a coating liquid. Then, the coating liquid and the ferrite particles were vacuum-degassed kneader (manufactured by Inoue Seisakusho). ), Stirred at 60 ° C. for 30 minutes, degassed by depressurizing while further heating, dried, and then sieved at 105 μm.

<Examples A1 to A5>
Using an image forming apparatus (manufactured by Fuji Xerox Co., Ltd., product name "AeosportV C3375"), the fixing device and the air supply pipe having the configuration shown in FIG. Further, the filter provided at the exhaust port of the image forming apparatus was removed. Then, the developer shown in Table 1 was stored in the developing device of the image forming apparatus.

・ Fixing device A
Specifically, a fixing device including a heating belt 62 and a pressure roll 61 shown in FIG. 2 as a first fixing unit and a heating roll 32 and a pressure roll 34 shown in FIG. 2 as a second fixing unit was used.
The fixing temperature of the heating belt 62 in the first fixing unit was set to 140 ° C., and the length (so-called nip width) of the first nip N6 formed by the heating belt 62 and the pressure roll 61 in the paper K transport direction was set to 8 mm. .
The fixing set temperature of the heating roll 32 in the second fixing unit was set to 180 ° C., and the length (so-called nip width) of the second nip N3 formed by the heating roll 32 and the pressure roll 34 in the paper K transport direction was set to 10 mm. .
Accordingly, the amount of heat given to the toner image by the heating belt 62 and the pressure roll 61 of the first fixing unit is set smaller than the amount of heat given to the toner image by the heating roll 32 and the pressure roll 34 of the second fixing unit. ing.
The difference [T1-T2] between the set fixing temperature [T1] of the heating belt 62 in the first fixing unit and the melting temperature [T2] of the release agent contained in the toner particles in the developer is shown in Table 1. Shown in

・ Air pipe A
Specifically, an air supply pipe provided with the duct 100 shown in FIG. 2 and further provided with the current plate 110 shown in FIG. 2 was installed.
The shape of the duct 100 is a rectangular shape having a long side in the width direction (the same direction as the axial direction of the heating belt 62) in a cross section perpendicular to the air supply direction, except for the air supply inlet 102. Therefore, the entire duct 100 has the same shape.
The width of the duct 100 is longer by 10 mm at both ends than the length of the paper K in the width direction.
The duct 100 is provided with fans 106 and 108 at the position shown in FIG. 2, and a plurality of fans are arranged from one end to multiple ends in the width direction of the duct 100, thereby moving from the air inlet 102 to the air outlet 104. An airflow is formed.

When viewed from the axial direction of the heating belt 62, the shape of the air supply inlet 102 is inclined with respect to the sheet K transport path, and has a shape in which the air supply inlet 102 faces the first nip N6.
The position where the end portion 102A of the air supply inlet 102 on the side close to the heating belt 62 is installed is 30 mm from the upstream end of the first nip N6, 20 mm from the surface of the heating belt 62, and paper K. The distance from the transport path is 20 mm.
The position where the end 102B of the air supply inlet 102 farther from the heating belt 62 is installed is a distance of 40 mm from the upstream end of the first nip N6 and a distance of 30 mm from the paper K transport path.

A current plate 110 is provided at the air supply inlet 102. One end of the current plate 110 is in contact with the end portion 102B of the air supply inlet 102 on the side farther from the heating belt 62, and is arranged so as to extend in the direction of the first nip N6 in parallel with the paper K transport path. One end (on the side close to the first nip N6) of the rectifying plate 110 that is not in contact with the end 102B of the air supply inlet 102 is arranged at a distance of 5 mm from the upstream end of the first nip N6. .
The width of the current plate 110 is set to be the same as the width of the duct 100. The thickness of the current plate 110 is 5 mm.
The current plate 110 has a hole 110A. The holes 110A are circular holes having a diameter of 5 mm, and are formed at intervals of 5 mm in the paper K transport direction and in a direction orthogonal to the transport direction.

The shape of the air supply outlet 104 is parallel to the paper K transport path when viewed from the axial direction of the heating roll 32, and the air supply outlet 104 faces the paper K passing through the transport path. It is arranged as follows.
The position where the air supply outlet 104 is installed is 20 mm from the paper K transport path.
The distance in the paper K transport direction between the end 104A of the air supply outlet 104 on the side close to the heating roll 32 and the downstream end of the second nip N3 (that is, the distance between the downstream end of the second nip N3 and the paper K transport path) The distance from the position corresponding to the end 104A) is 10 mm. In other words, the air supply outlet 104 is provided at a position where exhaust is performed from the air supply outlet 104 before the toner image is completely solidified on the sheet K after the second nip N3 has been inserted.
The position where the end 104A of the air supply outlet 104 on the side close to the heating roll 32 is installed is 20 mm from the surface of the heating roll 32.

The transport speed of the paper K is 121 mm / sec.
The flow velocity (air supply speed) of the air moving in the duct 100 is determined by the time required for the air entering from the air supply inlet 102 to be discharged from the air supply outlet 104 and reach the paper K transport path, and the first nip N6. The time until the sheet K inserted into the upstream end reaches the position where the air discharged from the air supply outlet 104 reaches is set to be synchronized.

The distance of the portion of the duct 100 closest to the heating belt 62 on the opposite side of the heating belt 62 from the paper K transport path (that is, the upper side in FIG. 2) is 20 mm.
The distance of the portion of the duct 100 closest to the heating roll 32 on the side opposite to the paper K transport path of the heating roll 32 (that is, the upper side in FIG. 2) is 20 mm.

<Examples B1 to B5>
Instead of the air supply pipe A installed in Examples A1 to A5, an air supply pipe having a configuration shown in FIG. 3, specifically, an apparatus including the following air supply pipe B is used. An image forming apparatus having the same configuration as in Examples A1 to A5 was prepared except that the fixing set temperature of the heating roll in the second fixing unit was set to the value shown in Table 1.

・ Air pipe B
A duct having the same configuration as the air supply pipe A was installed, except that the distance of the duct 200 to the heating belt 62 and the distance to the heating roll 32 were changed.
The distance of the portion of the duct 200 closest to the heating belt 62 on the side opposite to the paper K transport path of the heating belt 62 (that is, the upper side in FIG. 3) is 10 mm.
The distance of the portion of the duct 200 closest to the heating roll 32 on the side opposite to the paper K transport path of the heating roll 32 (that is, the upper side in FIG. 3) is 10 mm.

<Examples C1 to C5>
In the air supply pipe A installed in each of Examples A1 to A5, an air supply pipe (air supply pipe C) having a configuration in which the current plate 110 is not installed, and a fixing set temperature of a heating belt in a first fixing unit and a heating roll in a second fixing unit are used. An image forming apparatus having the same configuration as in Examples A1 to A5 was prepared, except that the fixing set temperature was set to the value shown in Table 1.

<Examples D1 to D5>
Instead of the fixing device A installed in Examples A1 to A5, a fixing device having a configuration shown in FIG. 5, specifically, a device including a fixing device B described below, and a fixing set temperature of a heating belt in a first fixing unit and An image forming apparatus having the same configuration as in Examples A1 to A5 was prepared except that the fixing set temperature of the heating roll in the second fixing unit was set to the value shown in Table 1.

・ Fixing device B
The fixing device A has the same configuration as that of the fixing device A except that the conveyance belts 42 and 44 shown in FIG.
The transport belts 42 and 44 sandwich the paper K inserted through the first nip N6 from both sides and transport the paper K to the second nip N3. The transport belt 42 directly contacts the surface of the paper K having the toner image. The transport belt 44 is in direct contact with the surface of the sheet K having no toner image.
The transport belt 42 is stretched over rolls 46A and 46B and stretched and driven to rotate, and the transport belt 44 is stretched stretched over rolls 48A and 48B and driven to rotate.

The length in the paper K transport direction of the area where the transport belt 42 is in direct contact with the paper K is 90% of the length from the downstream end of the first nip N6 to the upstream end of the second nip N3. It is.
The width of each of the transport belts 42 and 44 is 10 mm longer at each end than the length of the paper K in the width direction.

<Examples E1 to E5>
Instead of the fixing device A installed in Examples A1 to A5, a device including the following fixing device C in which the first rotating body pair in the first fixing unit is a two-roll rotating body pair, and a heating roll in the first fixing unit An image forming apparatus having the same configuration as in Examples A1 to A5 was prepared except that the fixing set temperature of the heating roll in the second fixing unit and the fixing set temperature of the second fixing unit were set to the values shown in Table 1.

・ Fixing device C
In the fixing device 50 shown in FIG. 2, except that the heating belt 62 and the pressure roll 61 corresponding to the first rotating body pair are changed to a two-roll rotating body pair having the same configuration as the heating roll 32 and the pressure roll 34. And the fixing device A.
The nip width of the first nip formed by the first rotating body pair and the nip width of the second nip formed by the second rotating body pair were both 20 mm.

<Comparative Example 1>
In the image forming apparatus according to the embodiment A1, the image forming apparatus does not include the air supply pipe A (that is, does not include the duct 100, the fans 106 and 108, and the rectifying plate 110), and the heating belt in the first fixing unit. An image forming apparatus having the same configuration as in Example A1 was prepared except that the fixing set temperature of the heating roll in the second fixing unit and the fixing set temperature of the second fixing unit were set to the values shown in Table 1.

<Reference Example 1>
In the embodiment A1, the developer contained in the developing device of the image forming apparatus is changed to the developer (C1), and the fixing temperature of the heating belt in the first fixing unit and the fixing of the heating roll in the second fixing unit are changed. An image forming apparatus having the same configuration as in Example A1 was prepared, except that the set temperature was set to the value shown in Table 1.

<Evaluation>
(Evaluation of low-temperature fixability)
A 4 cm × 5 cm unfixed image patch with a toner loading of 4.0 g / m ² was formed on J paper (A4) and printed under the condition that the process speed was fixed at 140 mm / sec. The fixing temperature in the fixing unit is changed every 5 ° C. within a range of 80 ° C. to 180 ° C., and the fixing temperature in the second fixing unit is fixed at the above-mentioned temperature, and fixing is performed, and no offset occurs. The lowest fixing temperature (minimum fixing temperature) was measured and evaluated according to the following criteria.
The evaluation criteria are as follows.
A (◎): Minimum fixing temperature is less than 120 ° C. B (○): Minimum fixing temperature is from 120 ° C. to less than 130 ° C. (△): Minimum fixing temperature is from 130 ° C. to less than 140 ° C. D (×): Minimum fixing temperature Is 140 ° C or higher

(Evaluation of image glossiness (gloss))
A 4 cm × 5 cm unfixed image patch with a toner loading of 4.0 g / m ² was formed on J paper (A4) and printed under the condition that the process speed was fixed at 140 mm / sec. The fixing temperature in the fixing unit and the second fixing unit was fixed at the above-mentioned temperature (° C.) and the image was fixed, and 20 images were output.
The finally output image was measured for glossiness (gloss, unit:%) using an evaluation device (BYK Gardner, micro-TRI-gross, 60 ° gloss) and evaluated according to the following criteria.
The evaluation criteria are as follows.
A (◎): Gloss is 30 or more B (（): Gloss is 20 or more and less than 30 C (△): Gloss is 5 or more and less than 20 D (×): Gloss is less than 5

(Evaluation of UFP)
Under an environment of a temperature of 22 ° C. and a humidity of 55% RH, an image having an image density of 100% was continuously formed on 1000 sheets of A3 size paper. During the image formation, the particle emission rate (PER _{10 PW} ) of UFP discharged from the image forming apparatus was measured at Fuji Xerox International Verification Center based on RAL UZ-171.
Based on the value of the measured particle emission rate [unit (number of particles / 10 minutes)], evaluation was made in three stages of G1 to G3. It should be noted that the comparative example 1 was provided with a device having no air supply pipe (duct) as a reference (G3) for relative evaluation. G1 has the smallest value, indicating that UFP is small.

From the above results, it was found that in each example, compared to the comparative example, the amount of UPF emission derived from the release agent contained in the toner was suppressed.
In the reference example, since the melting temperature of the release agent contained in the toner exceeded 100 ° C., the amount of UPF derived from the release agent contained in the toner was small.
Further, in the reference example, since the minimum fixing temperature was higher than that of the examples and comparative examples, the low-temperature fixability was low.

1Y, 1M, 1C, 1K Image forming unit 10 Image forming apparatus 32 Heating roll 32A Core material 32B Elastic layer 32C Surface layer 32D Heat source 34 Pressing roll 34A Core material 34B Elastic layer 34C Surface layer 42, 44 Transport belts 46A, 46B , 48A, 48B Roll 50 Fixing device 52 Covering plate 61 Pressure roll 61A Core 61B Elastic layer 61C Surface layer 62 Heating belt 63 Belt running guide 64 Press pad 65 Holder 66 Belt running assisting guide 69 Heating elements 100, 200, 300 Duct 102 , 202, 302 Inlet 102A, 102B End 104, 204, 304 Inlet 104A End 106, 108, 206, 306, 316 Fan 110, 210, 310 Rectifier 110A, 210A, 310A Hole 111 Photoconductor 112 Charger 113 Laser dew Unit 114 Developing unit 115 Intermediate transfer belt 116 Primary transfer roll 117 Photoconductor cleaner 118 Primary transfer unit 120 Secondary transfer unit 122 Secondary transfer roll 125 Back roll 126 Power supply roll 131 Driving roll 132 Support roll 133 Tension applying roll 134 Cleaning back roll 135 Intermediate transfer belt cleaner 140 Control unit 142 Reference sensor 143 Image density sensor 150 Paper storage unit 151 Paper supply roll 152 Transport roll 153 Transport guide 155 Transport belt 156 Fixing entrance guide 314 Air intake port 318 Tube K Paper N3 Second nip N6 1 nip

Claims (17)

An image carrier,
Charging means for charging the surface of the image holding member,
Electrostatic image forming means for forming an electrostatic image on the surface of the charged image carrier,
A developer containing a toner having toner particles containing a release agent having a melting temperature of 60 ° C. or more and 100 ° C. or less is contained, and the developer is used to develop an electrostatic charge image formed on the surface of the image holding member. Developing means for forming an image;
Transfer means for transferring the toner image to the surface of a recording medium,
Fixing means for fixing the toner image to the surface of the recording medium, comprising a first pair of rotating bodies that form a first contact area by contacting their outer peripheral surfaces with each other, wherein the toner image is transferred A first fixing unit that heats the recording medium by passing the recording medium through the first contact area; and a second pair of rotating bodies that form a second contact area by contacting their outer peripheral surfaces with each other. A fixing unit having a second fixing unit that heats the recording medium that has been inserted through the area by inserting the recording medium into the second contact area;
On the upstream side of the first contact area in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply inlet provided around the first contact area, and the air supply inlet of the second contact area. On the downstream side in the recording medium conveyance direction and on the side of the recording medium having the toner image, an air supply outlet provided around the conveyance path of the recording medium is connected, and the gas supplied from the air supply inlet is supplied to the air supply port. An air pipe that exhausts air from the air outlet toward the recording medium;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein a melting temperature of the release agent in the toner particles is 60 ° C. or more and 90 ° C. or less.   The image forming apparatus according to claim 1, wherein the release agent in the toner particles is paraffin wax.   The image forming apparatus according to claim 1, wherein the toner particles include a crystalline resin.   The image forming apparatus according to claim 4, wherein the content of the crystalline resin is 3% by mass or more and 20% by mass or less based on the mass of the toner particles.   The image forming apparatus according to claim 5, wherein the content of the crystalline resin is 5% by mass or more and 15% by mass or less based on the mass of the toner particles.   The image forming apparatus according to claim 1, wherein a toluene-insoluble content of the toner particles is 25% by mass or more and 40% by mass or less.   The image forming apparatus according to claim 1, wherein the shape factor SF1 of the toner particles is 140 or more.   The air supply outlet is provided at a position where air can be exhausted from the recording medium after being inserted into the second contact area and before the heated toner image is completely solidified. The image forming apparatus according to claim 1.   2. The apparatus according to claim 1, further comprising: a covering member that covers at least a part of a surface of the recording medium having the toner image on a conveyance path of the recording medium between the first fixing unit and the second fixing unit. Item 10. The image forming apparatus according to any one of items 9.   The image forming apparatus according to claim 1, further comprising a rectifying plate that forms an airflow flowing from an end of the first contact area on the upstream side in the recording medium conveyance direction to the air supply inlet. apparatus.   The image forming apparatus according to claim 1, further comprising a unit configured to heat an inside of the air supply pipe.   The amount of heat given to the toner image on the recording medium by heating at the first rotating body pair is smaller than the amount of heat given to the toner image on the recording medium by heating at the second rotating body pair. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 13, wherein a set fixing temperature in the first rotating body pair is 100 ° C. or more and 200 ° C. or less.   The image forming apparatus according to claim 14, wherein a set fixing temperature of the first rotating body pair is 120 ° C. or more and 200 ° C. or less.   The difference [T1-T2] between the set fixing temperature [T1] in the first rotating body pair and the melting temperature [T2] of the release agent in the toner particles is 40 ° C. or more and 120 ° C. or less. An image forming apparatus according to claim 14 or claim 15.   Rotation of a belt rotator that contacts the surface of the recording medium having the toner image to heat the toner image, and a roll rotator that contacts the opposite surface of the recording medium. A pair of rotating bodies, wherein the second rotating body pair contacts the surface of the recording medium having the toner image and heats the toner image; and a roll contacts the opposite surface of the recording medium. The image forming apparatus according to claim 1, wherein the image forming apparatus is a pair of a rotating body and a rotating body.