JP2006251498A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a good image with high glossiness by reducing unevenness in the glossiness of the image by forming a toner image using toner packed with wax to increase a releasing property. <P>SOLUTION: The image forming apparatus uses toner which contains resin binder, color material and the wax to improve the releasing property. A recording sheet with the toner image transferred by this toner is fixed by being heated and pressed by a fixing apparatus 15. The recording sheet after fixing the toner image is transported by a transporting roller 17 and sent to a wax coating apparatus 16. The wax coating apparatus includes a coating roll, a facing pressurizing contact roll and a supplying roll supplying the melted wax to the coating roll. The toner image on the recording sheet has the melted wax coated uniformly on it from the coating roll by being held between the coating roll and the pressure contact roll even when the unevenness in glossiness is produced due to contact with a transporting roll. After that, the unevenness in glossiness is solved by having the wax almost uniformly cooled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that forms a toner image by selectively attaching toner to a latent image due to a difference in electrostatic potential, transfers the toner image to a recording sheet, and then heats and pressurizes to form a fixed image. It is.

  An image forming apparatus using powdered toner can form a high-definition image and can output an image close to a photograph. In such a high-definition image, the demand for gloss is also high, and a high-gloss image is often required. For this reason, a so-called coated paper having a glossy coating layer formed on the surface is used as a recording sheet. After the toner image is transferred to the recording sheet, the toner image is sufficiently heated by a fixing device to obtain a highly glossy toner image. Has been made to form.

  However, when a high-gloss image is formed in this way, a portion where the gloss is uneven, that is, uneven gloss tends to occur, and the quality of the image may be deteriorated. A typical example of uneven luster is a so-called roll mark. As shown in FIG. 4, the toner image on the recording sheet P heated and pressed by the fixing device 101 is sandwiched between a pair of rolls 102 for conveying the recording sheet in a state where it is not sufficiently cooled. This occurs when the peripheral surface of the roll comes into contact with the toner image. Many of the roll marks 103 thus generated reduce gloss.

Techniques for reducing such roll marks are disclosed in, for example, Patent Document 1 and Patent Document 2.
The apparatus described in Patent Document 1 blows cooling air to the recording sheet that has passed through the fixing device, and lowers the temperature of the toner image until the recording sheet comes into contact with a conveyance roll provided on the downstream side of the fixing device. It is what.

Further, in the image forming apparatus described in Patent Document 2, leveling means is provided in the area where the toner is in a soft state on the downstream side of the fixing device so that the toner image is pressed against and smoothed. Yes. As a result, even if a roll mark is formed in contact with the roll for conveying the recording sheet, the surface of the toner image is smoothed by the leveling means and the roll mark is erased. In addition, a smoothing means is provided upstream from the transport roll to smooth the surface of the toner image and to prevent the occurrence of roll marks by bringing the toner image into contact with the transport roll while being cooled below the glass transition temperature of the toner. Has also been proposed.
Japanese Patent Laid-Open No. 2003-21978 Japanese Patent Laid-Open No. 2003-195663

  In recent years, in order to realize a high gloss color image similar to a photograph or printing, it has been proposed to use a toner having a good melting property encapsulating wax. This wax is used to improve the releasability from the heating member pressed against the toner image during fixing. Conventionally, oil was applied to the surface of a heating roll or the like in order to maintain releasability, but when heated to a high temperature to obtain a high gloss image, a large amount of oil was applied to maintain good releasability. I need. For this reason, streaks due to uneven application of oil occur, or the oil remains on the surface of the toner image and gets stuck in contact with the fixed image. Further, there arises a problem that the surface of the image cannot be added with a pencil or the like. Using a toner containing wax can solve these problems, and further, an image using such toner is transferred onto a coated paper and fixed in a state where it is sufficiently heated at a low fixing speed. By performing the above, a high gloss image can be obtained. Even in a state where the toner is in high temperature due to contact with the heating roll or the heating belt in the fixing device, the releasability from the heating roll or the like is secured by the wax.

  However, when a toner containing wax is used to improve the releasability as described above, noticeable gloss unevenness that does not occur when a conventional toner is used may occur. That is, as shown in FIG. 4, when the recording sheet heated and pressed by the fixing device and fixed with the toner image comes into contact with the recording sheet conveyance roll before being sufficiently cooled, the contacted portion becomes highly glossy. This causes uneven luster. This unevenness of gloss is different from a roll mark in which the gloss is lowered in an image using a normal toner as described in Patent Document 1, and is different from the roll mark in which the gloss is lowered. Easy and noticeable uneven brightness.

  It has been found that this uneven gloss does not occur if the conveying roll or the like is not brought into contact until the toner image and the recording sheet are sufficiently cooled. However, in order to obtain a high-gloss image, it is as thick as coated paper. When a recording sheet is used, the cooling rate is slow, and it may be difficult to sufficiently cool the sheet until it contacts the transport roll. Further, it has not been clear to what extent the toner image and the recording sheet can be cooled to prevent uneven gloss where the portion in contact with the roll or the like becomes extremely glossy. For example, Patent Document 2 describes that the toner is cooled to the glass transition temperature of the toner and then brought into contact with a roll or the like. However, when toner containing wax is used, cooling is performed based on the glass transition temperature of the toner. However, the correlation with the occurrence of uneven gloss is not good.

  Further, even when the surface of the toner image is mechanically smoothed using a leveling member as described in Patent Document 2, when toner containing wax is used, gloss unevenness is stably eliminated. I can't. In particular, it is often impossible to eliminate the uneven luster in which the portion in contact with the roll has a significantly high gloss. Then, the leveling member is heated by the repeated contact of the leveling member with the toner image, and thereby the function of eliminating the uneven glossiness may change significantly.

  Further, when the toner containing wax is used, gloss unevenness in which the contact portion with the roll becomes extremely high gloss occurs even if the unevenness state on the surface of the toner image hardly changes. It is not a fundamental solution to make it mechanically smooth.

  The present invention has been made in order to solve the above-described problems, and the object thereof is to reduce uneven gloss of a toner image using a toner containing a wax for improving releasability, It is to obtain a good image with high gloss.

  In order to solve the above-mentioned problems, the invention according to claim 1 includes an image forming unit that forms a toner image by selectively attaching powdery toner to a latent image due to a difference in electrostatic potential, and the toner. Transfer means for transferring an image directly to a recording sheet or via an intermediate transfer member, and fixing for fixing the toner image transferred on the recording sheet by applying pressure and heating to the recording sheet The toner includes a resin binder, a color material, and a wax that improves releasability, and the recording sheet that has passed through the fixing device is discharged from a sheet discharge port. Provided is an image forming apparatus having a wax application device for uniformly applying heated and melted wax to the image surface of the recording sheet before being sent out.

  It became clear in the process of completing the present invention that the wax contained in the toner was rapidly cooled from the melted state and the wax crystallized and became highly glossy when the temperature dropped below the melting point. The present invention has been made based on this fact, and a melted wax is applied on a fixed toner image, and a new wax layer is formed so as to cover the toner image. When the wax layer is cooled without contact with other members such as a transport roll, a uniform gloss layer is formed on the surface. Therefore, even if gloss unevenness occurs due to contact with the transport roll or the like after fixing, it is covered with the newly formed wax layer, and the uneven gloss due to the rapid cooling of the wax is eliminated. In addition, the wax is easier to melt than the binder resin of the toner, and can be applied so as to cover the surface with a simple device, and the uneven gloss can be effectively eliminated without increasing the size of the device. .

  The invention according to claim 2 is the image forming apparatus according to claim 1, wherein the wax coating device has a uniform cross section in the width direction of the recording sheet and contacts with the entire width of the recording sheet while rotating. And an application roll for applying the melted wax on the image surface, and a pressure contact roll that is pressed against the application roll and sandwiches the recording sheet with the application roll.

  In this image forming apparatus, a coating roll carrying wax melted on its surface is pressed against the entire surface of a recording sheet carrying a fixed toner image. Therefore, a thin layer of molten wax is uniformly formed on the recording sheet. Such a thin wax layer comes into contact with the toner image whose temperature after fixing is lowered and is uniformly cooled, and does not cause uneven gloss after the wax is applied.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect of the present invention, the image forming apparatus further includes a supply device that is in contact with the coating roll and continuously supplies the melted wax onto the peripheral surface of the coating roll. To do.

  By supplying continuously melted wax on the peripheral surface of the application roll, the application roll can apply a uniform thin wax layer on a recording sheet longer than the peripheral length. In addition, it is possible to stably form a uniform wax layer on each of the recording sheets that are successively conveyed.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the supply device includes a supply roll provided with a wax-impregnated layer impregnated with molten wax in the vicinity of the peripheral surface, and the impregnated wax. Heating means for maintaining the melted state, the supply roll is arranged in parallel with the coating roll, and is in contact with the peripheral surface of the coating roll.

In this image forming apparatus, the wax-impregnated layer of the supply roll is impregnated with molten wax, and as the coating roll rotates, the molten wax is stably supplied to the peripheral surface from the supply roll. The Therefore, a thin wax layer is uniformly formed on the recording sheet with which the coating roll is brought into contact.
In addition, since the supply roll has a heating means, the wax contained in the wax-impregnated layer is maintained in a molten state, and can be supplied thinly to the peripheral surface of the coating roll, and the thin wax layer can be stably formed on the recording sheet. Can be formed.

  The invention according to claim 5 is the image forming apparatus according to claim 4, wherein the wax-impregnated layer is formed of a material having a solubility parameter (SP value) substantially equal to the solubility parameter of the wax. And

  When the SP value of the material forming the wax-impregnated layer is set to be approximately the same as the SP value of the wax, the wax-impregnated layer is impregnated with the wax and swollen. Therefore, the wax-impregnated layer holds a large amount of wax in a molten state, and it is possible to stably supply the molten wax to the surface of the coating roll that comes into contact.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the second aspect, the coating roll has an elastic layer that is flexibly deformed at least near the surface.

  When the coating roll has an elastic layer, the coating roll can be evenly in close contact with the recording sheet in the axial direction when pressed against the recording sheet, and a uniform wax layer can be formed without uneven coating of wax. it can.

  As described above, in the image forming apparatus according to the present invention, after the toner image is heated and pressed by the fixing device, the molten wax is brought into contact with the transport roll or the like to cause uneven gloss such as a roll mark. Is uniformly applied on the toner image. This wax layer is uniformly cooled to give the surface a uniform gloss. Therefore, uneven gloss on the surface of the recording sheet on which the toner image is fixed is eliminated, and it is possible to form a good image with high gloss and no uneven gloss.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus includes four image forming units 10 a, 10 b, 10 c, and 10 d that form yellow, magenta, cyan, and black toner images, and has an endless belt shape so as to face these image forming units 10. The intermediate transfer member 11 is supported, and the peripheral surface is driven to rotate. On the downstream side of the position where the image forming unit 10 faces the intermediate transfer body 11, a transfer roll 12 is disposed so as to face the intermediate transfer body 11, and a conveyance path from the sheet tray 13 to the secondary transfer portion. The recording sheet is fed through 14. A fixing device 15 that heats and pressurizes the toner image to press the toner image onto the recording sheet is provided on the downstream side of the secondary transfer portion in the recording sheet conveyance path. Then, immediately before the recording sheet is sent out from the sheet discharge port 19 to a discharge tray 18 provided outside the apparatus, as shown in FIG. 2, a wax application device 16 for applying molten wax to the surface of the recording sheet is provided. The recording sheet sent out from the fixing device 15 is fed into the wax coating device 16 by the transport roll 17.

  Each of the image forming units 10a, 10b, 10c, and 10d has a photosensitive drum 1 (image carrier) on which an electrostatic latent image is formed, and around each photosensitive drum 1, A charging device 2 that charges the surface of the photosensitive drum substantially uniformly, a developing device 3 that forms a toner image by transferring toner to a latent image formed on the photosensitive drum, and a toner on the photosensitive drum 1 A transfer device 4 that primarily transfers an image onto the intermediate transfer member 11 and a cleaning device 5 that collects toner remaining on the photosensitive drum 1 after transfer are provided. An exposure device 6 for writing an electrostatic latent image by irradiating each uniformly charged photosensitive drum 1 with image light based on an image signal is provided.

  The photoconductive drum 1 is obtained by forming an organic photoconductive layer on the peripheral surface of a cylindrical member made of metal, and the metal portion is electrically grounded.

  The charging device 2 includes a roll-shaped member obtained by coating a stainless steel cylindrical cored bar with a medium-resistance rubber. The charging device 2 applies a voltage obtained by superimposing an AC voltage on a DC voltage to apply the surface of the photosensitive drum 1. It is charged to a desired voltage. The DC component Vh of the voltage applied to the charging device 2 is −600 [V], and the superimposed AC peak-to-peak value Vbpp is 1400 [V].

  The exposure device 6 generates a flashing laser beam based on an image signal, and scans this in the main scanning direction (axial direction) of each photosensitive drum 1 by a polygon mirror. As a result, electrostatic latent images corresponding to the images of the respective colors are formed on the surfaces of the respective photosensitive drums 1.

The developing device 3 uses a two-component developer containing toner and a magnetic carrier as a developer, and is magnetically attracted and conveyed to the developing roll 3a. Then, a layer having an appropriate thickness is formed on the developing roll 3 a by a regulating blade and supplied to a position facing the photosensitive drum 1. A developing bias voltage Vd = −500 [V] is applied to the developing roll 3 a in order to transfer the toner to the electrostatic latent image on the photosensitive drum 1.
The toner is charged negatively mainly by friction with a magnetic carrier, and contains a coloring material, a binder resin, and paraffin wax. The melting point of the binder resin is about 250 ° C., the glass transition temperature is about 100 ° C., and the melting point of the paraffin wax is about 90 ° C.

  The intermediate transfer body 11 disposed so as to face the image forming units 10a, 10b, 10c, and 10d is made of a resin film having a thickness of about 10 to 300 μm, and a polyimide film or the like is used. In addition, when the toner image is electrostatically transferred from the photosensitive drum 1 to the intermediate transfer member 11, a powder of a conductive material such as carbon black is mixed in the resin film so as not to disturb the image. The volume resistivity is adjusted to about 10 10 Ωcm.

  A driving roll 21 and a counter roll 22 are arranged inside the intermediate transfer body 11, and the intermediate transfer body 11 is stretched around these and moves around in the direction of arrow A shown in the drawing. Yes.

  The transfer roll 12 is provided at a position facing the opposing roll 22 and is pressed against the opposing roll 22 via the intermediate transfer body 11. The transfer roll 12 is a roll formed by forming an outer peripheral portion of a metal core material with a conductive rubber material, and a bias voltage for transfer is applied between the opposite roll 22. .

  The fixing device 15 includes a heating roll 15a having a built-in heating source and a pressure roll 15b pressed against the heating roll 15a, and these are arranged in parallel to form a nip portion that is pressed against each other. ing. The recording sheet on which the toner image has been transferred is fed into the nip portion, and is heated and pressed between the heated roll 15a and the pressure roll 15b that are rotationally driven, and the softened toner is pressed onto the recording sheet. It is supposed to be.

  The heating roll 15a is formed by forming an elastic body layer such as a heat-resistant rubber on the peripheral surface of a metal core, and forming a release layer on the surface thereof. A halogen heater is incorporated as a heating source. ing. The pressure roll 15b is obtained by coating a metal cored bar with a surface release layer.

  The conveyance roll 17 provided between the fixing device 15 and the wax coating device 16 is composed of a pair of roll members provided so as to face both sides of the recording sheet conveyance path. These roll members are arranged in parallel and the circumferential surfaces are pressed against each other, and one of them is driven to rotate so as to sandwich and transport the recording sheet. As shown in FIG. 2, the roll member includes a plurality of rolls having a small width in the axial direction, and a portion that contacts the roll and a portion that does not contact the roll are generated on the recording sheet.

  As shown in FIG. 3, the wax application device 16 includes an application roll 31 that is in contact with the surface of the recording sheet on which the toner image is fixed, a pressure contact roll 32 that is arranged in parallel with the application roll 31, and the above-described A supply roll 33 that supplies molten wax in contact with the coating roll 31, a storage tank 34 that accommodates the wax in a molten state, and an infiltrating member 35 that replenishes the molten wax from the storage tank to the supply roll. is doing.

  The coating roll 31 is obtained by laminating an elastic layer 31b and a surface layer 31c on the surface of a metal core 31a, and has a uniform cross section in a range in contact with the recording sheet. The hardness (JIS A6301) of the elastic layer 31b is adjusted to about 50 degrees or less. With this elastic layer, the surface of the coating roll is in close contact with the toner image on the recording sheet, and the molten wax can be uniformly applied.

  The pressure contact roll 32 is formed by forming a surface layer 32b on a metal roll 32a, and is in pressure contact with the peripheral surface of the application roll 31, and has a uniform cross section over the entire width of the recording sheet P in the same manner as the application roll 31. It has become. When the pressure contact roll 32 is driven to rotate, the recording sheet P is conveyed while being sandwiched between the application roll 31. As a result, the coating roll 31 is driven to rotate, and the melted wax is applied to the recording sheet P from the surface of the coating roll 31.

  The pressure roller 32 is supported so as to be retractable from a position where it is in pressure contact with the coating roll 31, and is separated from the coating roller 31 by being selected by the operator or in conjunction with the type of the selected recording sheet. Is set to When the pressure contact roll 32 moves backward from the position where it is in pressure contact with the application roll 31, the conveyed recording sheet is conveyed without coming into contact with the application roll 31 and sent out to the paper discharge tray 18.

The supply roll 33 includes a metal cored bar 33a, a wax-impregnated layer 33b formed so as to cover the metal cored bar 33a, and a heater 33c built in the cored bar. The heater 33c heats the wax contained in the wax-impregnated layer 33b and maintains it at a melting temperature or higher. The wax-impregnated layer 33b is made of an EPDM foam material, and the bubbles are not independent but continuous with each other so that the melted wax is easily impregnated. The solubility parameter (SP value) of this EPDM is about 8.0, which is almost the same as the value of the solubility parameter of wax. Therefore, the melted wax penetrates and swells.
The wax-impregnated layer 33b may be made of a material other than EPDM, but it is desirable to select a material in which the difference between the wax and the solubility parameter value is within about 2.0.

  The storage tank 34 is a container for storing wax that has been melted into a liquid state, and a heater 34 a that maintains the wax in a molten state in the storage tank 34 is provided at the bottom.

  The infiltrating member 35 is made of a fiber such as felt or non-woven fabric. One end of the infiltrating member 35 is immersed in the melted wax in the storage tank, and the other end is in contact with the supply roll 33. Yes. The infiltrating member 35 is infiltrated with wax melted from the storage tank 34 by a capillary phenomenon, and replenishes the supply roll 33 with wax from a contact portion with the supply roll 33.

Next, the operation of the image forming apparatus will be described.
Yellow, magenta, cyan, and black toner images are formed by the four image forming units 10a, 10b, 10c, and 10d provided to face the intermediate transfer member 11, respectively. The toner image is formed by the following process.
The surface of the photosensitive drum 1 is charged almost uniformly by the charging device 2, and laser light that is turned on / off according to an image signal is emitted from the exposure device 6. As a result, the charge at the position irradiated with light is attenuated, and a latent image is formed on the photosensitive drum 1 due to the difference in electrostatic potential. The electrostatic latent image on each photosensitive drum 1 is developed by toner transfer at a position facing the developing device 3, and a toner image is formed on the photosensitive drum 1.

  The formed color toner images are transferred onto the intermediate transfer body 11 in a superimposed manner by the transfer device 4. As a result, a color image in which a plurality of color toner images are superimposed on the intermediate transfer body 11 is formed. The toner images of a plurality of colors formed on the intermediate transfer body 11 are transferred onto the recording sheet conveyed from the sheet tray 13 at a position where the intermediate transfer body 11 faces the transfer roll 12 and sent to the fixing device 15. . The heating roll 15a of the fixing device is heated to a temperature sufficient to soften the toner, the recording sheet is sandwiched between the heating roll 15a and the pressure roll 15b, and the toner image is softened to record the recording sheet. Crimped on top.

  The recording sheet P that has passed through the fixing device 15 is nipped and conveyed by a conveyance roll 17 provided on the downstream side. At this time, in the toner image, the wax contained in the toner is rapidly cooled by the contact with the transport roll 17, and the contact portion with the roll becomes remarkably high gloss and uneven gloss is generated as shown in FIG. .

  Thereafter, the recording sheet is fed into the wax coating device 16 by the transport roll 17. In the wax coating device 16, the recording sheet carrying the toner image is fed between the coating roll 31 and the pressure roll 32 that are pressed against each other, and is conveyed by the rotation thereof. The application roll 31 is supplied with wax that is almost uniformly melted on the surface from the supply roll 33 that is in contact with the application roll 31, and this wax is applied almost uniformly and thinly on the surface of the recording sheet on which the toner image is formed. The The wax supplied to the application roll 31 is obtained by replenishing the supply roll 33 with the wax heated and melted in the storage tank 34 via the infiltrating member 35. The supply roll 33 is impregnated with the melted wax. The surface is in a swollen state. Accordingly, when the supply roll 33 comes into contact with the peripheral surface of the application roll 31 and both rotate, the peripheral surface of the application roller 31 is supplied with wax almost uniformly from the supply roll 33.

  In this way, a uniform thin wax layer is formed on the surface where the melted wax on the application roll 31 is pressed onto the recording sheet to form a toner image. Then, the recording sheet P is discharged from a sheet discharge port 19 to a discharge tray 18 provided outside the housing 20 of the apparatus. As a result, the surface of the toner image having uneven gloss is further covered with the wax layer, and the wax layer is uniformly cooled to have a uniform gloss. Accordingly, the surface of the recording sheet P on which the toner image is formed is free from uneven gloss, and a uniform high gloss image is obtained.

  When the image forming apparatus does not require coated paper, such as when coated paper is not required, or when an image that does not cause uneven glossiness is formed, the pressure application of the wax coating device 16 is performed. It can be controlled so that the roll 32 moves backward from the coating roll 31 and is separated. When the press roll 32 is thus retracted, the recording sheet carrying the toner image does not come into contact with the coating roll 31 and no wax is applied. Accordingly, the paper is fed to the paper discharge tray 18 in a fixed state. By controlling in this way, it is possible to improve the efficiency of image formation and increase the efficiency of power use.

  Further, when the melted wax is applied onto the recording sheet by bringing the pressure contact roll 32 into contact with the application roll 31, every time a recording sheet to which an image is transferred is conveyed, a sheet on which the image is not transferred is transferred to the sheet. It may be conveyed from the tray and stacked on the discharge tray 18 for discharge. When controlling in this way, it is assumed that the apparatus is provided with a plurality of sheet trays, and for sheets on which images are not transferred, a sheet that does not affect gloss even when contacted with heated wax is selected, and a sheet on which images are transferred Should be used by pulling out from another sheet tray. By controlling in this way, a sheet on which an image is not formed can be sandwiched between recording sheets coated with wax to protect the image surface.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic perspective view illustrating a partial arrangement state of a fixing device, a transport roll, and a wax coating device used in the image forming apparatus illustrated in FIG. 1. It is a schematic sectional drawing of the wax application | coating apparatus used with the image forming apparatus shown in FIG. FIG. 6 is a schematic perspective view for explaining problems in a conventional image forming apparatus, and shows a fixing device, a transport roll provided on the downstream side, and a roll mark generated on a recording sheet.

Explanation of symbols

1: Photosensitive drum, 2: Charging device, 3: Developing device, 4: Transfer device, 5: Cleaning device, 6: Exposure device, 10: Image forming unit, 11: Intermediate transfer member, 12: Transfer roll, 13: Sheet tray, 14: recording sheet conveyance path, 15: fixing device, 15a: heating roll, 15b: pressure roll, 16: wax coating device, 17: conveyance roll, 18: paper discharge tray, 19: sheet discharge port, 20: Image forming apparatus housing,
21: Drive roll, 22: Opposing roll,
31: coating roll, 31a: core metal, 31b: elastic layer, 31c: surface layer, 32: pressure contact roll, 32a: roll, 32b: surface layer, 33: supply roll, 33a: core metal, 33b: wax impregnated layer, 33c: heater, 34: storage tank, 34a: heater, 35: infiltrating member,

Claims (6)

Image forming means for selectively attaching powdery toner to a latent image due to a difference in electrostatic potential to form a toner image;
Transfer means for transferring the toner image directly to the recording sheet or to the recording sheet via an intermediate transfer member;
An image forming apparatus comprising: a fixing device that pressurizes and heats the toner image transferred onto the recording sheet and fixes the toner image on the recording sheet;
The toner includes a resin binder, a coloring material, and a wax that improves releasability,
An image forming apparatus comprising: a wax applying device that uniformly applies heated and melted wax to an image surface of the recording sheet before the recording sheet that has passed through the fixing device is sent out from a sheet discharge port. . The wax application device includes:
An application roll that has a uniform cross section in the width direction of the recording sheet and applies wax melted in contact with the entire width of the recording sheet while rotating;
The image forming apparatus according to claim 1, further comprising a pressure contact roll that is pressed against the application roll and sandwiches the recording sheet between the application roll.   The image forming apparatus according to claim 2, further comprising a supply device that is in contact with the coating roll and continuously supplies the melted wax onto the peripheral surface of the coating roll.   The supply device includes a supply roll provided with a wax-impregnated layer in the vicinity of a peripheral surface impregnated with molten wax, and heating means for maintaining the impregnated wax in a molten state, the supply roll being The image forming apparatus according to claim 3, wherein the image forming apparatus is arranged in parallel with the coating roll and is in contact with a peripheral surface of the coating roll.   The image forming apparatus according to claim 4, wherein the wax-impregnated layer is formed of a material having a solubility parameter (SP value) substantially the same as the solubility parameter of wax. The image forming apparatus according to claim 2, wherein the coating roll has an elastic layer that is flexibly deformed at least near the surface.

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