JP2012150352A - Foam generation device, fixing device, and image forming apparatus - Google Patents

Abstract

A foam generating apparatus capable of suppressing the occurrence of problems caused by liquid components contained in a foam liquid generated in a foam generating unit spreading on a wall surface forming a foam transport path, and the same A fixing device and an image forming apparatus having a bubble generating device are provided.
In a fixing liquid foaming device 500, a foam transport path (foam generation slit, foam outlet pipe 505, foam) through which a foamy fixing liquid F passes between a foam generation unit 502 and a foamy fixing liquid discharge port 501 is provided. Wall surfaces forming the manifold 503 and the discharge slit 504 have liquid repellency with respect to the liquid fixing liquid 210.
[Selection] Figure 1

Description

  The present invention relates to a bubble generating apparatus applicable to a fixing device used in an image forming apparatus such as a copying machine, a facsimile machine, and a printer. Specifically, it is applied as a fixing liquid foaming means for a fixing device in which a fixing liquid that dissolves or swells resin fine particles such as toner and fixes on a recording medium is made into a foamy fixing liquid by a fixing liquid foaming means and applied to the resin fine particles. The present invention relates to a possible bubble generating device, and a fixing device and an image forming apparatus including the same.

  2. Description of the Related Art Image forming apparatuses such as printers, facsimile machines, and copying apparatuses are apparatuses that form images including characters and symbols on recording media such as paper, cloth, and OHP sheets based on image information. There are various types of image forming apparatuses. Electrophotographic image forming apparatuses are widely used in offices because they can form high-definition images on plain paper at high speed. In such an electrophotographic image forming apparatus, from the viewpoint of fixing speed, fixed image quality, and the like, the toner on the recording medium that is the fixing medium is heated and softened or melted, and the softened toner is added. A thermal fixing method in which toner is fixed on a recording medium by pressing is widely used.

  More than half of the power consumption in the electrophotographic image forming apparatus adopting such a heat fixing method is consumed for heat treatment in the heat fixing type fixing device. On the other hand, from the viewpoint of measures against environmental problems in recent years, an image forming apparatus with low power consumption (energy saving) is desired. For this reason, there is a demand for energy saving in the fixing device that consumes more than half of the power consumption in the conventional image forming apparatus. The conventional heat fixing type fixing device consumes a lot of electric power for the heat treatment, so the fixing method for heating the toner to fix the toner is extremely lower than before, or the toner is heated. A fixing method that does not require this is desired. In particular, a non-heat fixing method in which toner is fixed on a recording medium without heating the toner is ideal in terms of low power consumption.

  In such a non-heat fixing method, a toner image is formed by applying a fixing solution containing a softening agent that softens the toner by dissolving or swelling at least a part of the resin component of the toner to the toner image on the surface of the recording medium. There is known a wet fixing method for fixing a toner (for example, a fixing method used in a fixing device described in Patent Documents 1 to 6). In the wet fixing system, a fixing solution is applied to, sprayed, or dropped on an unfixed toner image to soften the toner that forms the toner image, and then the softened toner is dried on a recording medium to thereby form a toner image. Is fixed on the recording medium. As described above, the wet fixing type fixing device does not need to perform heat treatment to soften the toner, so that energy saving can be realized as compared with the thermal fixing method.

  The fixing device described in any of Patent Documents 1 to 4 uses a coating roller that is a contact-type fixing liquid application unit, and the fixing liquid is applied to a fixing medium such as a recording medium or an intermediate transfer body while the fixing liquid remains liquid. By applying the toner, the fixing liquid is applied to the unfixed toner image on the fixing liquid application target. In the configuration in which fixing is performed by applying such a liquid fixing solution to a toner image, it is extremely difficult to achieve both the application of a small amount of the fixing solution to the toner image on the fixing liquid application target and the prevention of toner offset to the application roller. There was a problem. Hereinafter, this problem will be described.

  In a configuration in which a fixing liquid is applied to an unfixed toner image on a fixing liquid application target using a coating roller, the thickness of the fixing liquid layer on the coating roller is undetermined in order to apply a small amount of the fixing liquid to the fixing liquid application target. When it is made thinner than the layer of the toner image, the following problem may occur. After the surface of the coating roller comes into contact with the fixing liquid application target, the surface of the coating roller peels off from the fixing liquid application target, and is generated by a liquid film of the fixing liquid that is not applied to the fixing liquid application target and remains on the coating roller surface. The toner particles in the toner layer on the fixing liquid application target are pulled by the surface tension. As a result, offset toner particles adhere to the surface of the coating roller, and the toner image on the fixing liquid application target after peeling off from the coating roller is greatly disturbed.

Conversely, if the thickness of the fixing liquid layer on the coating roller is made sufficiently thicker than that of the unfixed toner layer, the amount of liquid is large at the position where the coating roller is peeled off from the fixing liquid application target. The surface tension is less likely to act on the toner particles of the toner layer on the fixing liquid application target. This makes it difficult for toner to adhere to the application roller side, but a large amount of the fixing liquid is applied to the surface of the fixing liquid application target. For this reason, the toner particles flow due to the diffusion of the fixing liquid due to the excessive fixing liquid on the target to which the fixing liquid is applied, and the image quality deteriorates, or the drying time of the fixing liquid becomes long, causing a problem in fixing responsiveness. In addition, a remarkable residual liquid feeling (a wet feeling when touching paper) is generated on the recording medium. In addition, when the fixing solution contains water, when the amount of fixing solution applied to a recording medium containing cellulose such as paper is large, the recording medium such as paper curls remarkably, and an apparatus such as an image forming apparatus There is a risk that a paper jam will occur when the recording medium is transported inside.
As described above, in the configuration in which the fixing liquid is applied using the application roller, if the amount of the fixing liquid applied is too large, the image quality deteriorates due to the flow of toner particles, and the fixing responsiveness due to the longer drying time of the fixing liquid. And a problem that paper jam easily occurs depending on the recording medium. On the other hand, if a configuration in which a small amount of fixing solution is applied to prevent these problems, the toner particles are offset on the surface of the application roller as described above.
Therefore, in the configuration in which the fixing solution is applied by the application roller, a small amount of the fixing solution is applied to the toner layer on the object to which the fixing solution is applied in order to improve the fixing responsiveness, reduce the residual liquid feeling, and prevent curling. It is extremely difficult to achieve both offset prevention.

As fixing methods that can achieve both the application of a small amount of a fixing solution and the prevention of toner offset, Patent Documents 5 to 7 describe a foam-forming fixing solution in which bubbles are dispersed in a solution using a bubble generating device. A configuration is described in which a foamy fixing solution is applied to a toner image on a recording medium to which a fixing solution is applied. Thus, the density of the fixing solution (the value obtained by dividing the weight of the fixing solution by its volume, hereinafter referred to as the bulk density) can be lowered by making the fixing solution foam. For this reason, it is possible to increase the film thickness of the fixing solution on the surface of the coating roller with a smaller amount of fixing solution than before, and to reduce the influence of the surface tension of the liquid on the toner particles on the fixing solution application target. Further, since the amount of the fixing solution is small, it is possible to suppress the residual liquid feeling on the recording medium. Further, since the foam-like fixing solution is less likely to flow than a normal liquid fixing solution, it is possible to prevent image deterioration caused by the toner particles on the fixing solution application target being caused to flow by the fixing solution. Therefore, by performing fixing using a foamy fixing solution as in the fixing devices described in Patent Documents 5 to 7, it is possible to fix the toner image without disturbing with a smaller amount of fixing solution applied than before.
In the fixing devices described in Patent Documents 5 to 7, when the generated foamy fixing solution is applied on the surface of an application member such as an application roller, the area to be applied is in the width direction orthogonal to the surface movement direction of the application member. Give it to spread. By applying the foam-like fixing liquid to the application member that moves on the surface with spreading in the width direction, a layer of the foam-like fixing liquid can be formed on the surface of the application member.

  In addition, in order to obtain good fixability with a configuration in which a foam-like fixing solution is applied to a toner image as in the fixing devices described in Patent Documents 5 to 7, the bubble diameter of the foam-like fixing solution is small to some extent. It is required to be. Good fixability can be obtained by applying a foamy fixing solution containing minute bubbles to the toner image on the object to which the fixing solution is to be applied. The fixing devices described in Patent Document 6 and Patent Document 7 have a configuration capable of quickly generating a foam-like fixing solution containing minute bubbles of a desired size.

However, as in the fixing devices described in Patent Document 6 and Patent Document 7, even if a foam-like fixing solution containing minute bubbles is generated, the foam-like fixing solution applied on the surface of the coating member is not affected in the width direction. There may be unevenness in the distribution of the bubble diameter and the distribution of the bulk density. This is thought to be due to the following reasons.
That is, in the foam generation device, the foam-like fixing solution generated in the foam generation unit that mixes the fixing solution and air to form the foam-like fixing solution passes through the bubble conveyance path and faces the surface of the coating member. It is given to the surface of the applicator member from the foam outlet arranged in the. At this time, the foam-like fixing solution that contacts the wall surface that forms the bubble conveyance path spreads out due to the wettability of the liquid component (liquid fixing solution) that forms the bubbles with the wall surface of the bubble conveyance path, and the fixing solution on the wall surface. A film is formed. At this time, the amount of the fixer in the foam-like fixer is reduced by the amount wetted and spread on the wall surface of the bubble transport path, and the thickness of the wall of the fixer that partitions the bubbles between the bubbles is reduced. . Thereby, it becomes easy to produce a bubble breakage, the bubble which adjoins by connecting with a bubble breakage, and a bubble diameter becomes large. Further, the bulk density is lowered by reducing the amount of the fixing solution in the foamy fixing solution. As described above, the phenomenon that the bubble diameter of the foam-like fixing solution generated in the bubble generation unit increases or the bulk density decreases is that the longer the distance of the bubble conveyance path from the bubble generation unit to the bubble discharge port is, In particular, it is considered that the smaller the channel cross-sectional area of the bubble transport path, the more prominent. This is because the longer the distance of the bubble transport path, the greater the chance that the foam fixing solution contacts the wall surface of the foam transport path. This is because the ratio of the foamy fixing solution that contacts the wall surface increases.
In the configuration in which the foam fixing solution generated by the foam generating device is applied so as to spread in the width direction of the coating member, the bubble transport through which the discharged foam fixing solution has passed is determined by the position in the width direction at the foam outlet. The distance of the road and the cross-sectional area of the flow path are different. For this reason, it is considered that the bubble-shaped fixing solution applied on the surface of the coating member is uneven in the bubble diameter distribution and the bulk density distribution in the width direction.
Further, the uneven distribution of the bubble diameter leads to the unevenness of the fixability, and there is a possibility that the final image may be uneven.

  In the above-described problem, the problem of the foam generating apparatus using the liquid fixing solution as the foam fixing solution has been described. However, the liquid to be foamed from the normal liquid is not limited to the fixing solution, and the small diameter is not limited. The same problem can arise if it is a foam generating device that generates a foamy liquid.

  This invention is made | formed in view of the above problem, The objective originates in the liquid component contained in the foamy liquid produced | generated by the foam production | generation part wets and spreads on the wall surface which forms a foam conveyance path. It is an object of the present invention to provide a bubble generating device capable of suppressing the occurrence of defects, and a fixing device and an image forming apparatus having the bubble generating device.

In order to achieve the above object, the invention of claim 1 includes a foam generation unit that generates a foam liquid by mixing a liquid supplied from a liquid supply unit and a gas supplied from a gas supply unit; In a foam generating apparatus having a foam discharge port for discharging the foamed liquid generated in the foam generating unit to the outside of the apparatus, the foam transport through which the foamed liquid passes between the foam generating unit and the foam discharge port At least a part of the wall surface forming the path is liquid repellent with respect to the liquid.
Further, the invention of claim 2 is characterized in that, in the foam generating device of claim 1, liquid repellent processing is performed on a wall surface of the bubble transport path having liquid repellency with respect to the liquid. is there.
The invention according to claim 3 is the foam generating device according to claim 1 or 2, wherein a contact angle of the liquid with respect to the wall surface of the bubble transport path having liquid repellency with respect to the liquid is 60 [°] or more. It is characterized by being.
According to a fourth aspect of the present invention, there is provided the foam generating apparatus according to any one of the first to third aspects, wherein the liquid and gas mixing section in the foam generating section is formed by two opposing wall surfaces facing each other. A gas that is a thin-layered space formed by surrounding the gap with a side wall surface, and that connects a gas supply path through which the gas supplied from the gas supply means toward the bubble generation unit passes to the bubble generation unit The supply port is composed of a plurality of minute through holes.
Further, the invention according to claim 5 is the foam generating device according to claim 4, wherein the gas supply port is arranged such that the plurality of micro through holes are arranged in a direction perpendicular to the thickness direction of the gap between the two opposing wall surfaces. A liquid supply port that is formed on the wall surface and that connects the liquid supply path through which the liquid supplied from the liquid supply means toward the bubble generation unit passes is connected to the bubble generation unit between adjacent gas supply ports. It is characterized by being a plurality of minute through holes formed therebetween.
According to a sixth aspect of the present invention, there is provided a fixing liquid foam comprising a liquid fixing liquid containing a softening agent that softens resin fine particles by dissolving or swelling at least a part of a resin, in which bubbles are dispersed in the liquid. A fixing liquid supply means for supplying the liquid fixing liquid to the fixing liquid foaming means, a gas supply means for supplying the gas to the fixing liquid foaming means, and a fixing liquid carrying the resin fine particles. In the fixing device, the fixing liquid foaming means for fixing the resin fine particles softened by applying the foamy fixing solution to a recording medium, the fixing liquid applying means for applying the foamy fixing solution to the surface of the application target The foam generating apparatus according to any one of claims 1 to 5 is used as the shaping means.
According to a seventh aspect of the present invention, there is provided a toner image forming means for forming a toner image on a recording medium using a toner containing resin fine particles containing a resin and a colorant, and a toner carrying a toner image transferred to the recording medium. An image forming apparatus comprising: a fixing unit that applies a fixing liquid to the surface of an image carrier or a surface of a recording medium that carries a toner image as a surface to which the fixing liquid is applied, and fixes the toner image on the recording medium. The fixing device according to claim 6 is used as the fixing unit.

  According to the present invention, since at least a part of the wall surface forming the bubble transport path has liquid repellency with respect to the liquid, it is possible to suppress the liquid component of the foam liquid in contact with the wall surface from spreading. Therefore, there is an excellent effect that it is possible to suppress the occurrence of problems caused by the liquid component contained in the foamy liquid being wet and spreading on the wall surface forming the foam conveyance path.

FIG. 3 is an explanatory diagram schematically illustrating a fixing device according to an embodiment. 1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is a partially enlarged configuration diagram illustrating an enlarged part of an internal configuration of a printer unit in the copier. FIG. 3 is a partially enlarged view showing one of four image forming units in the copier. FIG. 4 is an enlarged explanatory view of a portion where the application roller of the fixing device according to the embodiment contacts the transfer paper. FIG. 3 is an enlarged schematic diagram of a foamy fixing solution. The enlarged front view of a bubble production | generation part. The enlarged top view of a bubble production | generation part. The expanded side view of a bubble production | generation part. The enlarged front view of the position vicinity of the position where the lower end part of a fixing liquid foaming apparatus and the upper end part of an application | coating roller oppose. The expansion perspective view of the space which forms a bubble manifold and a discharge slit. The enlarged side view of the position vicinity of the position where the lower end part of a fixing liquid foaming apparatus and the upper end part of an application | coating roller oppose. An enlarged explanatory view in the vicinity of the bubble generation slit, (a) is an explanatory view when the water repellent finish is applied to the wall surface, and (a) is an explanatory view when the water repellent finish is not applied to the wall surface. A partially enlarged explanatory view of the foam manifold and the discharge slit, (a) is an explanatory view when the water repellent finish is applied to the wall surface, (a) is an explanatory view when the water repellent finish is not applied to the wall surface. Schematic diagram of film thickness control of foamy fixing solution by film thickness regulating blade, (a) is an explanatory diagram when the gap width is narrowed, (b) is an explanatory diagram when the gap width is widened. FIG. 6 is an explanatory diagram of a fixing device according to a modification. Explanatory drawing of the fixing apparatus of the 2nd modification. Explanatory drawing of the fixing apparatus of the 3rd modification. An explanatory view when the film thickness of the fixing solution is thin in a fixing device using a liquid fixing solution, (a) is a schematic explanatory view of the fixing device, and (b) is an application roller that contacts the transfer paper and applies the fixing solution. Explanatory drawing of the application | coating position where a transfer paper contacts. FIG. 3 is an explanatory diagram when the film thickness of the fixing solution is sufficiently thick in the fixing device using the liquid fixing solution.

Hereinafter, an embodiment in which the present invention is applied to a copying machine (hereinafter referred to as a copying machine 100), which is an image forming apparatus that forms an image by electrophotography, will be described. In the present embodiment, the image forming apparatus having the fixing device including the bubble generating apparatus of the present invention is described as a copying machine. However, other image forming apparatuses such as a printer and a facsimile may be used.
First, a basic configuration of the copying machine 100 according to the embodiment will be described. FIG. 2 is a schematic configuration diagram illustrating the copying machine 100 according to the embodiment. The copying machine 100 includes a printer unit 1, a paper feeding device 40, and a document conveyance reading unit 50. The document conveyance reading unit 50 includes a scanner unit 150 that is a document reading device fixed on the printer unit 1, and an ADF 51 that is a document conveyance device supported by the scanner unit 150.

  The paper feeding device 40 separates and feeds two paper feeding cassettes 42 arranged in multiple stages in the paper bank 41, a feeding roller 43 that feeds the transfer paper P from the paper feeding cassette 42, and the fed transfer paper P. A separation roller 45 supplied to the path 44 is provided. Further, a plurality of transport rollers 46 for transporting the transfer paper P to the paper transport path 37 of the printer unit 1 are also provided. Then, the transfer paper P in the paper feed cassette 42 is fed into the paper transport path 37 in the printer unit 1.

  The scanner unit 150 fixed on the printer unit 1 has a fixed reading unit 151 and a moving reading unit 152 as reading means for reading an image of the document MS. A fixed reading unit 151 having a light source, a reflection mirror, an image reading sensor such as a CCD, etc. is disposed immediately below a first contact glass (not shown) fixed to the upper wall of the casing of the scanner unit 150 so as to contact the document MS. ing. When the document MS conveyed by the ADF 51 passes on the first contact glass, the image reading sensor 153 receives the light from the light source through the plurality of reflection mirrors while sequentially reflecting the light emitted from the light source on the document surface. . Thereby, the document MS is scanned without moving the optical system including the light source and the reflection mirror.

On the other hand, the moving reading unit 152 is disposed directly below a second contact glass (not shown) fixed to the upper wall of the casing of the scanner unit 150 so as to come into contact with the document MS, and is arranged on the right side of the fixed reading unit 151 in the drawing. Therefore, an optical system including a light source and a reflection mirror can be moved in the left-right direction in the figure. Then, in the process of moving the optical system from the left side to the right side in the figure, the light emitted from the light source is reflected by a document (not shown) placed on the second contact glass and then passed through a plurality of reflecting mirrors. The light is received by an image reading sensor 153 fixed to the scanner body. Thereby, the original MS is scanned while moving the optical system.
In this way, the scanner unit 150 scans the document MS and, based on the image information obtained by the image reading sensor 153, the optical writing device 2 drives the light source, as will be described later, to form four drum-shaped photoconductors. The laser beam L is irradiated toward 4 (K, Y, M, C).

  FIG. 3 is a partially enlarged configuration diagram illustrating a part of the internal configuration of the printer unit 1 in an enlarged manner. The printer unit 1 includes an optical writing device 2, four image forming units 3 (K, Y, M, and C) that form toner images of respective colors K, Y, M, and C, a transfer unit 90, and a paper transport unit 28. , A registration roller pair 33, a fixing device 60, and the like. The optical writing device 2 is disposed above the four image forming units 3 (K, Y, M, and C), and a light source such as a laser diode or LED (not shown) disposed in the optical writing device 2. Is driven to irradiate the four photosensitive drums 4 (K, Y, M, C) with the laser light L. By this irradiation, an electrostatic latent image is formed on the surface of the photoreceptor 4 (K, Y, M, C) which is a latent image carrier, and this latent image is developed into a toner image through a predetermined development process. Is done. Note that the subscripts K, Y, M, and C added after the reference numerals indicate specifications for black, yellow, magenta, and cyan. The toner corresponding to each color is made of a resin material colored in each color, and at least a part of these resin materials are dissolved or swollen by a fixing solution of the fixing device 60 described later, and the toner is softened.

  Each of the image forming units 3 (K, Y, M, and C) supports the photosensitive member 4 that is a latent image carrier and various devices disposed around the photosensitive member 4 as a single unit by a common support. It can be attached to and detached from the copying machine 100 main body. Taking the black image forming unit 3K as an example, this has a developing device 6K for developing the electrostatic latent image formed on the surface of the photosensitive member 4K into a black toner image in addition to the photosensitive member 4K. Further, it also includes a drum cleaning device 15K that cleans transfer residual toner adhering to the surface of the photoreceptor 4K after passing through a primary transfer nip for K, which will be described later. In the copying machine 100, a so-called tandem type in which four image forming units 3 (K, Y, M, and C) are arranged to face an intermediate transfer belt 91 described later so as to be arranged along the endless movement direction. It is configured.

FIG. 4 is an enlarged view of one of the four image forming units 3 (K, Y, M, C). The four image forming units 3 (K, Y, M, and C) have substantially the same configuration except that the colors of the toners to be used are different from each other. Therefore, in FIG. , M, and C are omitted. As shown in FIG. 4, the image forming unit 3 includes a charging roller 5 as a charging device, a developing device 6, a drum cleaning device 15, a static elimination lamp 22 as a static elimination device, and the like around the photoreceptor 4.
Further, a primary transfer roller 95 of the primary transfer device is disposed at a position facing the photoconductor 4 with the intermediate transfer belt 91 interposed therebetween.

  In the copying machine 100, a drum-shaped member in which a photosensitive layer is formed by coating a photosensitive organic photosensitive material on a base tube made of aluminum or the like is used as the photosensitive member 4. However, an endless belt may be used as the photoreceptor.

The developing device 6 carries a two-component developer containing a magnetic carrier (not shown) and a non-magnetic toner on a developing roller 12 that is a developer carrying member. Then, toner is supplied to the electrostatic latent image on the photosensitive member 4 in the developing region which is the opposite portion between the developing roller 12 and the photosensitive member 4 to visualize the electrostatic imagination. The developing device 6 includes a developing unit in which the developing roller 12 is disposed, and a developer containing unit that contains a two-component developer supplied to the surface of the developing roller 12. The developer accommodating portion is provided with a stirring member (not shown) that agitates the two-component developer to be accommodated.
The developing roller 12 includes a non-magnetic cylindrical developing sleeve that is rotatably arranged, and a magnet roller that is non-rotatably provided therein. The magnet roller has a plurality of magnetic poles that are sequentially arranged in the rotation direction of the developing sleeve. Each of these magnetic poles applies a magnetic force to the two-component developer on the developing sleeve at a predetermined position in the rotation direction. As a result, the two-component developer in the developer accommodating portion is attracted and carried on the surface of the developing sleeve, and a magnetic brush is formed along the magnetic force lines on the surface of the developing sleeve.
The magnetic brush is transported to the developing area after being regulated to an appropriate layer thickness when passing through a position facing a developer regulating member (not shown) as the developing sleeve rotates. Then, development is performed by transferring toner onto the electrostatic latent image by a potential difference between the developing bias applied to the developing sleeve and the electrostatic latent image on the photosensitive member 4. Further, the two-component developer constituting the magnetic brush that has passed through the developing area and then returned to the developing device 6 again with the rotation of the developing sleeve is developed under the influence of the repulsive magnetic field formed between the magnetic poles of the magnet roller. After detachment from the sleeve surface, it is returned to the developer container. A toner concentration sensor (not shown) is disposed in the developer accommodating portion, and the toner concentration of the two-component developer in the developer accommodating container is within a predetermined range based on the detection result by the toner concentration sensor. As described above, a toner replenishing device (not shown) is controlled so that an appropriate amount of toner is replenished to the two-component developer.

  As shown in FIG. 3, a transfer unit 90 is disposed below the four image forming units 3 (K, Y, M, C). The transfer unit 90 includes an intermediate transfer belt 91 as a toner image carrier stretched by a plurality of stretching rollers (92, 93, 94), and the first stretching roller 92 sandwiches the intermediate transfer belt 91. A belt cleaning device 32 is disposed at the facing position. The belt cleaning device 32 is arranged to remove toner remaining on the intermediate transfer belt 91 after passing through a secondary transfer nip described later.

In the transfer unit 90, the intermediate transfer belt 91 is moved endlessly in the clockwise direction in the figure (the direction of arrow A in FIG. 3) while contacting the photoreceptor 4 (K, Y, M, C). As a result, primary transfer nips for K, Y, M, and C where the photoreceptors 4 (K, Y, M, and C) and the intermediate transfer belt 91 abut are formed. In the vicinity of the primary transfer nips for K, Y, M, and C, the intermediate transfer belt 91 is moved to the photosensitive member 4 by a primary transfer roller 95 (K, Y, M, and C) disposed in the belt loop. It is pressed toward (K, Y, M, C). A primary transfer bias is applied to the four primary transfer rollers 95 (K, Y, M, C) by a power source (not shown). Thus, in the primary transfer nip for K, Y, M, and C, the primary image that electrostatically moves the toner image on the photoreceptor 4 (K, Y, M, and C) toward the intermediate transfer belt 91 that is a transfer body. A transfer electric field is formed. In the drawing, toner images are successively superimposed at the primary transfer nips on the surface of the intermediate transfer belt 91 that sequentially passes through the primary transfer nips for K, Y, M, and C with endless movement in the clockwise direction. Primary transcription. By this superimposing primary transfer, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the surface of the intermediate transfer belt 91.
The primary transfer device according to the present embodiment employs a configuration including a primary transfer roller 95 as a primary transfer member, but a conductive brush, a non-contact corona charger, or the like can also be employed as the primary transfer member.

  In FIG. 4, untransferred toner that has not been primarily transferred to the intermediate transfer belt 91 adheres to the surface of the photoreceptor 4 after passing through the primary transfer nip. This transfer residual toner is removed from the surface of the photoreceptor 4 by the drum cleaning device 15 of the image forming unit 3.

As the drum cleaning device 15, a device that scrapes off and removes transfer residual toner from the surface of the photoconductor 4 after passing through the primary transfer nip by a polyurethane rubber cleaning blade 16 in contact with the photoconductor 4 is used. . The cleaning blade 16 is bonded (hot melt) to a metal support member fixed to the casing of the image forming unit 3, and comes into contact with the photoconductor 4 in the counter direction. The counter direction is the direction of the blade such that the front end side of the cleaning blade 16 cantilevered by the support member is positioned upstream of the rear end side (free end side) in the rotation direction of the photosensitive member 4. .
Here, the toner recovered by the drum cleaning device 15 is recovered by the developing device 6 and reused by a recovery screw and a toner recycling device (not shown).

  The static eliminator included in the image forming unit 3 of the present embodiment has a configuration including a static eliminator lamp 22, and irradiates light to initialize the surface potential of the photoreceptor 4. The surface of the photoreceptor 4 that has been neutralized by the static elimination lamp 22 is uniformly charged by a charging roller 5 that generates a discharge with the photoreceptor 4 by applying a charging bias, and then the light from the optical writing device 2 is used. Write processing is performed.

  The charging device provided in the image forming unit 3 is a contact charging type charging device employing a charging roller 5. This charging device uniformly charges the surface of the photosensitive member 4 by bringing the charging roller 5 into contact with the surface of the photosensitive member 4 and applying a voltage to the charging roller 5. In addition, as a charging device for uniformly charging the photosensitive member 4, a charging device of a non-contact charging type using a scorotron charger or the like can be used instead of the charging roller type.

  As shown in FIG. 3, in the printer unit 1, an endless paper conveyance belt 29, which is a secondary transfer belt, is hung between a driving roller 30 and a secondary transfer roller 31 below the transfer unit 90 in the drawing. A paper transport unit 28 is provided as a secondary transfer unit that passes and moves endlessly. In the copying machine 100, the intermediate transfer belt 91 and the paper transport belt 29 are sandwiched between the secondary transfer roller 31 of the paper transport unit 28 and the lower stretching roller 94 of the transfer unit 90. As a result, a secondary transfer nip is formed in which the surface of the intermediate transfer belt 91 and the surface of the paper transport belt 29 abut. A secondary transfer bias is applied to the secondary transfer roller 31 by a power source (not shown). On the other hand, the lower stretching roller 94 of the transfer unit 90 is grounded, and a secondary transfer electric field is formed in the secondary transfer nip. The member that forms the secondary transfer nip in contact with the intermediate transfer belt 91 is not limited to a belt-like member such as the paper transport belt 29, and a roller-like transfer roller may be used.

A registration roller pair 33 is disposed on the right side of the secondary transfer nip in the figure. The transfer paper P fed from the paper feed cassette 42 into the paper transport path 37 in the printer unit 1 is sandwiched between the rollers of the registration roller pair 33 and stopped.
The registration roller pair 33 sends the transfer paper P sandwiched between the rollers to the secondary transfer nip at a timing at which the transfer paper P can be synchronized with the four-color toner image on the intermediate transfer belt 91. In the secondary transfer nip, the four-color toner image on the intermediate transfer belt 91 is secondarily transferred onto the transfer paper P under the influence of the secondary transfer electric field and the nip pressure, and becomes a full color image combined with the white color of the transfer paper P. The transfer paper P, which has passed through the secondary transfer nip and has the toner image transferred to the surface thereof, is separated from the intermediate transfer belt 91 and is held on the surface of the paper transport belt 29, and to the fixing device 60 along with its endless movement. It is conveyed.

  The transfer residual toner that has not been transferred to the transfer paper P at the secondary transfer nip adheres to the surface of the intermediate transfer belt 91 that has passed through the secondary transfer nip. This transfer residual toner is scraped off and removed by the belt cleaning device 32 arranged so that the cleaning member contacts the intermediate transfer belt 91.

  The transfer paper P conveyed to the fixing device 60 is sent out from the fixing device 60 after the full color image is fixed by applying a fixing liquid in the fixing device 60, as will be described in detail later. 10 is discharged.

  As shown in FIG. 2, in the copier 100, a switchback device 36 that is a transfer paper reversing device is disposed below the paper transport unit 28 and the fixing device 60. When performing image formation on both sides, the path of the transfer paper P that has passed through the fixing device 60 and has undergone image fixing processing on one side is switched to the switchback device 36 side by controlling the switching claw 34. Therefore, the transfer paper P is reversed and conveyed toward the secondary transfer transfer nip again. Then, the transfer sheet P on which the image is subjected to the secondary transfer process and the fixing process on the other side is discharged onto the discharge tray 10.

Next, the fixing device 60 will be described.
FIG. 1 is an explanatory view schematically showing a fixing device 60 of the present embodiment. Note that the resin fine particles in the present embodiment are toner particles.
The fixing device 60 includes a fixing liquid bottle 220 that contains a liquid fixing liquid 210 containing a softening agent that softens toner particles that are resin fine particles by dissolving or swelling at least a part of the toner made of a resin material. Further, the fixing device 60 includes a fixing liquid foaming device 500 that is a fixing liquid foaming means that uses the liquid fixing liquid 210 as a foamy fixing liquid F in which bubbles are dispersed in the liquid. Further, the fixing device 60 includes a fixing liquid supply pump 200 and an air pump 300. The fixer supply pump 200 is a fixer supply unit that supplies a liquid fixer to the fixer foaming device 500, and the air pump 300 is a gas supply unit that supplies air as a gas to the fixer foaming device 500. Further, the fixing device 60 includes an application roller 61 as a fixing liquid applying unit that applies a foamy fixing liquid F to the surface of the transfer paper P that is a target for applying a fixing liquid that carries an unfixed toner image T composed of toner particles. . Further, the fixing device 60 includes a pressure roller 62 at a position facing the application roller 61 with the transfer paper P interposed therebetween.

  The fixing liquid supply pump 200 sucks the liquid fixing liquid 210 in the fixing liquid bottle 220 and supplies the liquid fixing liquid 210 to the fixing liquid foaming device 500 by pumping the liquid fixing liquid 210 to the fixing liquid transport pipe 230. In addition, the air pump 300 sucks outside air through the air filter 310 and supplies the air to the fixing liquid foaming device 500 by pressure-feeding the air to the air conveyance pipe 330. The fixer foaming device 500 supplied with the liquid fixer 210 and air generates a foamy fixer F with a configuration described in detail later, and discharges the foamy fixer F from the foamy fixer outlet 501. As a result, the foam-like fixing liquid F is supplied to the surface of the application roller 61.

The foamy fixing solution F supplied onto the surface of the application roller 61 passes through a position facing the film thickness regulating blade 63 by the surface movement of the application roller 61 rotating in the direction of arrow B in FIG. Reaches the coating position C where the pressure roller 62 and the pressure roller 62 face each other. Then, the foamy fixing solution F on the surface of the application roller 61 is applied to the unfixed toner image T on the transfer paper P at the application position C. The softened toner particles are fixed to the transfer paper P by applying the foamy fixing solution F to the unfixed toner image T at the application position C.
As described above, in the fixing device 60, the transfer paper P carrying the unfixed toner image T is fixed in a bubble form on the surface of the application roller 61 at the application position C where the nip is formed by the application roller 61 and the pressure roller 62. Contact liquid F. Then, the foamy fixing solution F permeates the toner layer of the unfixed toner image T by the pressure applied by the pressure roller 62. The permeated fixing solution is softened by dissolving or swelling at least a part of the toner, and the softened toner is re-cured to fix the toner to the transfer paper P.

Here, an advantage of a fixing method in which a fixing solution in the form of foam instead of a normal liquid like the fixing device 60 of the present embodiment is applied to the unfixed toner image T and fixed on the transfer paper P will be described.
First, a fixing device using a conventional wet fixing method in which an ordinary liquid fixing solution is applied unlike the fixing device 60 of the present embodiment will be described.

  Patent Document 1 describes a wet-fixing type fixing device using an oil-in-water fixing solution in which an organic compound that can dissolve or swell toner and is insoluble or hardly soluble in water is dispersed and mixed in water. Yes. In this fixing device, unfixed toner is sprayed or dripped on the surface of the fixing object disposed at a predetermined position to dissolve or swell the toner, and then the fixing object is dried. is there.

  However, the fixing device of Patent Document 1 uses an oil-in-water type fixing solution in which an organic compound that is insoluble or hardly soluble in water is dispersed and mixed in water. For this reason, when a large amount of fixing liquid is applied to the unfixed toner, a recording medium (fixed object) such as transfer paper absorbs moisture of the fixing liquid, and wrinkles and curls are generated on the recording medium. This significantly impairs the stable and high-speed conveyance of the recording medium required for the image forming apparatus. Therefore, if water is removed from the fixing liquid applied to the recording medium by evaporating a large amount of water contained in the fixing liquid using a drying apparatus, the power consumption of the image forming apparatus using the thermal fixing method is reduced. You will need comparable power.

  In addition, several oil-based fixing solutions in which a material that dissolves or swells toner is dissolved in an oil-based solvent have been proposed as fixing solutions that do not repel water-repellent unfixed toner. For example, Patent Document 2 discloses, for example, an aliphatic dibasic acid ester as a component of a material that dissolves or swells a resin component constituting a toner, and a non-volatile dimethyl silicone as a diluent (solvent). A diluted (dissolved) fixer has been proposed. In Patent Document 3, as a fixing solution for an unfixed toner image, 8 to 120 parts by volume of silicone oil is mixed with 100 volumes of a solvent that dissolves toner and is compatible with silicone oil. A compatible fixing solution is proposed. By using such a fixing liquid, an unfixed toner image formed by an electrostatic method can be clearly and easily fixed on a recording medium without disturbing the image. Such an oil-based fixing solution contains an oil-based solvent having a high affinity with the water-repellent-treated unfixed toner, so that the toner is dissolved or swollen without repelling the water-repellent-treated unfixed toner, The toner can be fixed on the recording medium.

  In such a conventional wet fixing method, since the fixing liquid is applied to the toner image on the recording medium in a normal liquid state, a small amount of the fixing liquid is applied to the toner image on the recording medium and the toner offset to the fixing roller. There was a problem that it was extremely difficult to achieve both preventions. This problem will be described with reference to FIGS.

FIG. 19 is an explanatory diagram of a fixing device 600 that uses a liquid fixing liquid of a conventional wet fixing method. FIG. 19A is a schematic explanatory diagram of a fixing device 600 using a liquid fixing solution. FIG. 19B shows the proximity of the transfer paper P, which is a recording medium, in the fixing device 600 that uses the liquid fixing liquid, and the application roller 61, which is an application member that applies the liquid fixing liquid 210 in contact with the transfer paper P. FIG.
As shown in FIG. 19A, in a configuration in which the liquid fixing liquid 210 is applied to the unfixed toner image T on the transfer paper P using the application roller 61, a small amount of the liquid fixing liquid 210 is applied to the transfer paper P. Further, when the film thickness of the liquid fixing liquid 210 on the surface of the application roller 61 is smaller than the thickness of the toner layer of the unfixed toner image T, the result is as shown in FIG. The liquid fixer 210 on the surface of the application roller 61 is applied to the transfer paper P from the application roller 61 at the application position where the surface of the application roller 61 is in contact with the transfer paper P. As indicated by the arrow F1, there are some that remain on the surface of the application roller 61 even after passing through the application position. Then, at the position where the surface of the application roller 61 is separated from the transfer paper P, the unfixed toner is generated by the surface tension (acting in the direction of arrow F2 in FIG. 19) generated by the liquid film of the liquid fixing liquid 210 remaining on the surface of the application roller 61. The toner particles of the image T are pulled. As a result, the offset toner particles Tb adhere to the surface of the application roller 61, and the image of the fixed toner image Ta on the transfer paper P after peeling off from the application roller 61 is greatly disturbed.

  Conversely, when the film thickness of the liquid fixing liquid 210 on the surface of the application roller 61 is made sufficiently thicker than the layer thickness of the unfixed toner image T, the result is as shown in FIG. At the position where the surface of the application roller 61 is separated from the transfer paper P, the amount of the liquid fixing liquid 210 is large, so that the surface tension due to the liquid film on the surface of the application roller 61 hardly acts on the toner particles of the unfixed toner image T. This makes it difficult for the offset toner to adhere to the application roller 61 side. However, since a large amount of the liquid fixing liquid 210 is applied to the surface of the transfer paper P, toner particles on the transfer paper P are caused to flow by the excessive liquid fixing liquid 210 and image quality is deteriorated, or the liquid applied to the transfer paper P The drying time of the fixing liquid 210 becomes long and a problem occurs in the fixing response. In addition, a noticeable residual liquid feeling (a wet feeling when the paper is touched by hand) occurs on the transfer paper P. Further, when the liquid fixing liquid 210 contains water, when the amount of the liquid fixing liquid 210 applied to the transfer paper P containing cellulose such as paper as a recording medium is large, the transfer paper P such as paper is remarkably used. The paper curls, and there is a risk that a paper jam occurs when the recording medium is transported in an apparatus such as an image forming apparatus.

  As described above, in the configuration in which the liquid fixing liquid 210 is applied using the application roller 61, if the amount of the liquid fixing liquid 210 applied is too large, the image quality deteriorates due to the toner particles flowing, and the drying time of the liquid fixing liquid 210. There is a problem that fixing responsiveness is lowered due to the increase in length. Further, depending on the material of the recording medium, there is a problem that paper jam is likely to occur. On the other hand, if a small amount of liquid fixer 210 is applied to prevent these problems, offset toner particles Tb adhere to the surface of the application roller 61 as described with reference to FIG. End up. Therefore, it is possible to achieve both the application of a small amount of the fixing liquid to the toner layer on the transfer paper P and the prevention of the toner offset to the application roller 61 in order to improve the fixing response, reduce the residual liquid feeling, and prevent the curling. Extremely difficult.

  As a fixing method capable of achieving both the application of a small amount of a fixing solution and the prevention of toner offset, Patent Documents 5 to 7 disclose that the fixing solution is a foamed fixing solution in which bubbles are dispersed in the solution. A configuration is described in which a liquid is applied to a toner image on a recording medium by an application roller. Thus, since the density of the fixing liquid (the value obtained by dividing the weight of the fixing liquid by its volume, hereinafter referred to as “bulk density”) can be lowered by making the fixing liquid foamy, the amount of the fixing liquid is smaller than the conventional amount. With this fixer, the thickness of the fixer on the coating roller surface can be increased. Furthermore, the influence of the liquid surface tension on the toner particles on the recording medium can be reduced. Also, since the amount of the fixing solution is small, the residual liquid feeling on the recording medium can be suppressed, and the foam-like fixing solution is less likely to flow than the normal liquid fixing solution. It is also possible to prevent image deterioration due to the occurrence of image deterioration. Therefore, by performing fixing using a foamy fixing solution as in Patent Documents 5 to 7, it is possible to fix the toner image without disturbing with a smaller amount of fixing solution applied than in the past.

  In order to obtain good fixability with a configuration in which a foamy fixing solution is applied to a toner image as in the fixing device described in Patent Documents 5 to 7, the bubble diameter of the foaming fixing solution must be small to some extent. Is required. Good fixability can be obtained by applying a foamy fixing solution containing minute bubbles to the toner image on the object to which the fixing solution is to be applied. However, when producing a foam liquid containing fine bubbles from a normal liquid liquid, it is difficult to reduce the diameter of the bubbles, and a process of foaming a normal liquid fixer by foaming (hereinafter referred to as initial foaming). It takes a long time to generate minute bubbles from the beginning. Therefore, as in the fixing device described in Patent Document 5, in the configuration in which the foamy fixing solution generated by the initial foaming is supplied to the application roller as it is and used for fixing, bubbles containing fine bubbles suitable for fixing are used. There is a problem that it takes a long time to produce the fixing solution.

  With respect to such a problem, the fixing liquid foaming device provided in the fixing device described in Patent Document 6 includes a large diameter foam generating unit that generates a foam fixing liquid having a large foam diameter by initial foaming, and a large diameter foam generation. And a small-diameter bubble generating unit that generates a foam-like fixing solution having a fine bubble diameter by separating the foam-like fixing solution generated in the part. More specifically, the liquid foaming liquid is foamed by initial foaming by passing a normal liquid fixing liquid (hereinafter referred to as a liquid fixing liquid) and air through a microporous sheet in a large-diameter foam generating unit. A foam-like fixing solution having a larger bubble diameter than the bubble diameter is produced. Thereafter, the foam fixing solution obtained by the initial foaming is transported to the small-diameter foam generation unit, and in the small-diameter foam generation unit, a shearing force is applied to the foam fixing solution having a large foam diameter in an apparatus having a rotating body inside. To reduce the diameter of the foam. That is, in the fixing liquid foaming device disclosed in Patent Document 6, an initial foaming device (large-diameter foam generating unit) and a small-diameter device (small-diameter foam generating unit) are provided separately. In this way, after generating a foam fixing solution containing large bubbles, a shear force is applied to the foam fixing solution to separate large bubbles to obtain a foam fixing solution with a small bubble diameter. Compared with the method of generating foamy liquid containing fine bubbles, the foamed fixing liquid containing fine bubbles of a desired size can be generated quickly compared with the method of generating foam from the liquid liquid.

However, the fixing liquid foaming device included in the fixing device of Patent Document 6 has a problem that the device becomes large. This is due to the following reason.
The fixer foaming device of Patent Document 6 is provided with a device for initial foaming and a device for reducing the diameter separately, and a foamy fixer having a large foam diameter from the device for initial foaming to the device for reducing the diameter. Is transported through piping (tube). At this time, the foam-like liquid has a larger fluid resistance than a normal liquid, and a large pressure is required when the foam-like fixer is pumped by applying pressure with a pump. The longer the piping that forms the transport path for transporting the foam-like fixer, the greater the pressure required to pump the foam-like fixer. For this reason, a pump with a large output is required to transport the fixing solution in the fixing solution foaming device, and the larger the output, the larger the pump tends to increase in size. The device becomes large.
Further, in the fixing liquid foaming device provided in the fixing device of Patent Document 6, since the shearing force is applied to the foam fixing solution having a large bubble diameter by the rotating body to reduce the diameter, the mechanism and the rotating body including the rotating body are provided with the rotating body. A drive source for transmitting the drive is required, which leads to a large apparatus.
When the fixing liquid foaming device becomes large, it leads to an increase in the size of the fixing device and the image forming apparatus provided with the fixing liquid foaming device. Therefore, the foaming fixing device is desired to be able to generate a desired small-diameter bubble and to be small. It is.

  As described above, the configuration of the apparatus that performs the initial foaming is not limited to the apparatus that allows the fixing liquid and air to pass through the microporous sheet. For example, initial foaming can be performed even in a configuration in which air is sent into the fixing solution from an air discharge port inserted into the stored fixing solution and foamed by bubbling. Further, even when the liquid fixing solution and air are passed through a conveyance path provided with rotating stirring blades instead of the microporous sheet, initial foaming can be performed by entraining air in the liquid fixing solution by stirring. it can. These configurations have a foam diameter equal to or greater than that of the foam-like fixer obtained by initial foaming using a microporous sheet, and an apparatus that performs initial foaming in the same manner as the above-described fixer foaming device. In addition, a device for reducing the diameter is required, which causes a problem that the device becomes large.

In the patent document 7, the present applicant generally uses a device having a configuration similar to that of a micromixer (also referred to as a microreactor) used for mixing and reaction of two types of liquids. A fixing device used as a foam generating device is proposed.
In general, a micromixer includes two liquid supply paths that respectively supply two types of liquids and a mixing unit to which the two liquid supply paths are connected. In this configuration, liquid is mixed and reacted in the mixing section, and the result is obtained from the outlet. The inventors of Patent Document 7 connect an air pump that feeds air using one of the liquid supply paths of the micromixer as an air supply path, and a fixer supply pump that supplies a liquid fixer to the other liquid supply path. Then, it was found that when the air and the fixing solution were fed, a foamy fixing solution was obtained as a result.

Further, the foam fixing solution obtained by the foam generating device described in Patent Document 7 has a foam diameter larger than that of the foam fixing solution obtained by the device that performs the initial foaming by passing the microporous sheet described in Patent Document 6. Is a sufficiently small foam-type fixing solution, and the foam-type fixing solution obtained at this time has microbubbles to such an extent that good fixability can be obtained by applying the foam-type fixing solution to the toner image. It was confirmed to be a foamy fixer containing.
Furthermore, it was confirmed that the foam generating device described in Patent Document 7 can generate a foam-like fixing solution containing fine bubbles as quickly as the fixing solution foaming device included in the fixing device of Patent Document 6.
Further, the output of the pump used as the air pump or the fixing liquid supply pump used in the foam generation device described in Patent Document 7 is sufficiently smaller than the output of the pump included in the fixing liquid foaming device described in Patent Document 6. It was confirmed that there was.
Since a pump with a small output can be used, the size of the pump can be reduced. Furthermore, there is no need for a device that applies a shearing force to the foamy fixing solution by the rotating body to reduce the diameter, so a mechanism that includes a rotating body that applies the shearing force and a drive source that transmits the drive to the rotating body are also unnecessary. Become.
Thus, it is not necessary to provide a device for initial foaming and a device for reducing the diameter, respectively, and the pump can be made smaller than before, and a mechanism or a rotating body including a rotating body that applies a shearing force can be provided. Since a drive source for transmitting the drive is not necessary, the size can be reduced as compared with the bubble generating device provided in the conventional fixing device.
In the fixing device 60 of the present embodiment, the fixing liquid is bubbled using the fixing liquid foaming device 500 as the foam generating device having the same configuration as the micromixer (also referred to as a microreactor), as in the above-mentioned Patent Document 7. In this configuration, a foamy fixing solution F having a lower bulk density than the liquid fixing solution 210 is applied to the unfixed toner image T on the transfer paper P as a recording medium.

FIG. 5 is an enlarged explanatory view of a portion (application position C) where the application roller 61 contacts the transfer paper P in the fixing device 60 of the present embodiment.
As shown in FIG. 5, by using the fixing liquid foaming device 500 as a liquid fixing liquid 210 in which bubbles are dispersed in the liquid, the bulk density of the fixing liquid can be lowered, and a small amount of fixing liquid can be used. The film thickness of the fixing solution on the surface of the application roller 61 can be increased. Furthermore, since the influence of the surface tension of the fixing solution is suppressed, it has been found that the resin fine particles can be prevented from being offset to the coating roller 61 even if the amount of the fixing solution is small.

Further, as a result of extensive investigations by the present inventors, when the size of the resin fine particles is about 5 [μm] to 10 [μm], it is undecided that the foamed fixing solution F is resin fine particles without disturbing the fine particle layer. It was found that the bubble diameter range of the foam-like fixing liquid F is suitable for applying to the toner particles of the toner image T is about 5 [μm] to 50 [μm].
FIG. 6 is an enlarged schematic diagram of the foam-like fixing solution F. As shown in FIG. 6, the foam-like fixing solution F in which a large number of bubbles Fb are dispersed in the solution becomes foamed. The liquid film boundary (hereinafter referred to as a plateau boundary Fa) that divides each of the above.
The bulk density of the foam-like fixing liquid F supplied to the application roller 61 is preferably in the range of about 0.01 [g / cm ³ ] to 0.1 [g / cm ³ ].

Next, the fixer foaming device 500 which is a foam generating device will be described.
A fixing liquid foaming apparatus 500 shown in FIG. 1 includes a foam generation unit 502, a foam outlet pipe 505, a foam manifold 503, and a discharge slit 504. In the foam generation unit 502, the liquid fixer 210 and air supplied from the fixer transport pipe 230 and the air transport pipe 330 are mixed with each other, thereby generating a foam-like fixer F. The generated foam-like fixing solution F is passed to the foam manifold 503 through the foam outlet tube 505, and is spread by the foam manifold 503 in the width direction of the application roller 61 (direction perpendicular to the paper surface of FIG. 1). 504 is supplied to the surface of the application roller 61 from the foamy fixing solution outlet 501.

7 to 9 are enlarged explanatory views of a space through which fluid (fixing solution and air) in the vicinity of the bubble generating unit 502 of the fixing solution foaming device 500 passes. FIG. 7 is an enlarged front view of the foam generating unit 502 viewed from the same direction as FIG. 1, and FIG. 8 is an enlarged top view of a DD cross section in FIG. FIG. 9 is an enlarged side view as a cross-sectional view of the EE cross section in FIGS. 7 and 8. FIG. 7 is a cross-sectional view taken along the line GG in FIGS. 8 and 9.
7 to 9, the space through which the liquid fixing solution 210 passes is a hatched portion, the arrow Lc in the drawing indicates the flow of the liquid fixing solution 210, and the arrow Ac in the drawing indicates the flow of air. Furthermore, an arrow Fc in the figure indicates the flow of the foamy fixing solution F.

The liquid fixing liquid 210 supplied from the fixing liquid transport pipe 230 flows into the liquid manifold 240 of the foam generation unit 502, spreads in the width direction, and passes through the liquid flow paths 250 arranged in the width direction to generate bubbles. It flows into the slit 506. On the other hand, the air supplied from the air conveyance pipe 330 flows into the gas manifold 340 of the bubble generation unit 502, spreads in the width direction, passes through the gas flow paths 350 arranged in the width direction, and forms the bubble generation slit 506. Flow into.
As shown in FIGS. 8 and 9, the liquid channel 250 and the gas channel 350 communicate with the bubble generation slits 506 alternately in the width direction. As an example, the bubble generation unit 502 illustrated in FIG. 8 has a channel pitch P3 of 220 [μm] and a channel width K of 70 [μm]. In this example, 23 liquid channels 250 and 22 gas channels 350 are formed.
The slit width Ws of the bubble generation slit 506 is desirably 50 [μm] to 200 [μm], and is 100 [μm] in the present embodiment. The width direction slit length Wa is 3.0 [mm] to 5.0 [mm]. Furthermore, the diameter Wd of the bubble outlet tube 505 having a circular cross section is about 2.0 [mm].

In the bubble generation unit 502, a portion where the bubble generation slit 506 communicates with the liquid flow path 250 is a fixing liquid supply port (liquid supply port), and a portion where the bubble generation slit 506 communicates with the gas flow path 350 is an air supply port. (Gas supply port). A fixing liquid supply port that supplies the liquid fixing liquid 210 into the bubble generation slit 506 and an air supply port that supplies air at the upper end of the bubble generation slit 506 extend in the longitudinal direction of the cross section of the bubble generation slit 506. It becomes the state arrange | positioned alternately along.
By supplying the liquid fixer 210 with the bubble generating unit 502 having such a structure, the liquid fixer 210 and the air flow from the alternately arranged fixer supply ports and air supply ports, thereby generating bubbles. The liquid fixing solution 210 and air are mixed in the slit 506 to generate a foam-like fixing solution F, and the generated foam-like fixing solution F flows into the bubble outlet tube 505.

  10 to 12 are enlarged explanatory views of the space through which the fluid in the vicinity of the bubble manifold 503 and the discharge slit 504 on the downstream side of the bubble outlet tube 505 of the fixing liquid foaming device 500 passes. FIG. 10 is an enlarged front view of the vicinity of a position where the lower end portion of the fixing liquid foaming device 500 and the upper end portion of the application roller 61 face each other as viewed from the same direction as FIG. FIG. 11 is an enlarged perspective view of a space in which the bubble manifold 503 and the discharge slit 504 are formed. FIG. 12 is an enlarged side view of the vicinity of the position where the lower end portion of the fixing liquid foaming device 500 and the upper end portion of the application roller 61 face each other, as viewed from the side where the width direction of the application roller 61 is the left-right direction. In FIG. 12, the cross section of the application roller 61 is indicated by the hatched portion.

The foam-like fixer F that has flowed from the bubble generation slit 506 into the bubble outlet tube 505 passes through the bubble outlet tube 505 and flows into the bubble manifold 503. The foam manifold 503 communicates with the discharge slit 504 in the entire width direction, but the discharge slit 504 has a discharge width Wp of 500 [μm] or less and a flow path of the foam manifold 503 (depth is 1.5 [mm] to 2]. The fluid resistance to the foam-like fixing liquid F that passes is larger than (about 0.0 mm). For this reason, the foam-like fixing solution F that has flowed into the bubble manifold 503 from the bubble outlet tube 505 does not immediately flow into the discharge slit 504, and is filled in the bubble manifold 503 having a smaller fluid resistance than the discharge slit 504. . After the foam fixing solution F is filled in the foam manifold 503, the foam fixing solution F further flows into the foam manifold 503 from the foam outlet tube 505, so that the foam fixing solution F in the foam manifold 503 is pushed out. In this way, it flows into the discharge slit 504. Thereafter, the foam-like fixing liquid F that has passed through the ejection slit 504 is ejected from the foam-like fixing liquid discharge port 501, whereby the foam-like fixing liquid F can be supplied to the surface of the application roller 61.
Further, the foam-like fixing liquid F filled in the foam manifold 503 extending in the width direction is discharged from the foam-like fixing liquid discharge port 501 through the discharge slit 504, so that the coating roller 61 that moves on the surface is covered. Thus, the foamy fixing solution can be applied with a spread in the width direction.

  The fixing liquid foaming device 500 of the present embodiment has a width direction discharge slit length Wt of 20 [mm]. For this reason, as shown in FIG. 12, the fixing liquid foaming device 500 has a foam generation unit 502, a foam outlet pipe 505, and a foam manifold 503 so that a plurality of discharge slits 504 are continuously arranged in the width direction. And a plurality of ejection slits 504 are arranged along the width direction. In the fixing liquid foaming device 500 of the present embodiment, 15 are arranged.

Next, features of the fixing liquid foaming device 500 of this embodiment will be described.
In the fixing liquid foaming apparatus 500 according to the present embodiment, a liquid repellent process is performed on the wall surfaces that form the foam generation slit 506, the foam outlet pipe 505, the foam manifold 503, and the discharge slit 504.
In the fixing liquid foaming device 500, the foam-like fixing liquid F passes between the foam-generating unit 502 and the foam-like fixing liquid discharge port 501 by the foam generation slit 506, the foam outlet pipe 505, the foam manifold 503, and the discharge slit 504. The bubble conveyance path is configured. By subjecting the wall surface of the bubble conveyance path to liquid repellency, the wall surface of the bubble conveyance path has liquid repellency with respect to the fixing liquid. Here, the wall surface having liquid repellency with respect to the fixing solution means that the contact angle of the fixing solution with respect to the wall surface is 60 [°] or more. As described above, since the wall surface of the bubble conveyance path has liquid repellency with respect to the fixing liquid, it is possible to suppress the liquid component of the foam-like fixing liquid F in contact with the wall surface from spreading.
Hereinafter, the configuration of the present embodiment in which liquid repellent processing is performed on the bubble transport path and the configuration in which liquid transport repellent processing is not performed on the transport path will be described in comparison with FIGS. 13 and 14.

FIG. 13 is an enlarged explanatory view of the vicinity of the bubble generation slit 506 indicated by a region α in FIG. FIG. 13A is an explanatory diagram of the present embodiment, and is an explanatory diagram of a state in which the foam-like fixing liquid F is passed through the foam generation slit 506 whose wall surface has been subjected to liquid repellent processing. FIG. 13B is an explanatory diagram of a comparative example, and is an explanatory diagram of a state in which the foam-like fixing liquid F is passed through the foam generation slit 506 whose wall surface is not subjected to liquid repellent processing.
A broken line arrow Fc in FIG. 13 indicates the flow of the foamy fixing solution F, and an arrow Lc indicates the flow of the liquid component (fixing solution) flowing out from the plateau boundary Fa of the foamed fixing solution F.

  As shown in FIG. 13B, when the foam-like fixing liquid F is passed through the foam generation slit 506 whose wall surface has not been subjected to liquid repellent processing, the foam generation slit 506 from the plateau boundary Fa is indicated by an arrow Lc. The amount of the fixer that spreads on the wall surface of the toner increases. Since the amount of the fixing solution attached to the wall surface of the bubble generation slit 506 is large, the film thickness of the plateau boundary Fa becomes thin on the downstream side of the bubble generation slit 506, and bubbles are easily broken. When bubble breakage occurs, the adjacent bubbles Fb across the plateau boundary Fa communicate with each other, and the bubble diameter increases. As described above, when bubble breakage occurs in the bubble generation slit 506, the bubble diameter distribution is uneven between the portion where the bubble breakage occurs and the portion where the bubble breakage does not occur.

  On the other hand, as shown in FIG. 13 (a), when the foam-like fixing liquid F is passed through the foam generation slit 506 whose wall surface has been subjected to liquid repellency, as shown by the arrow Lc, the foam generation slit is formed from the plateau boundary Fa. The amount of the fixer that spreads on the wall surface 506 is reduced. Since the amount of the fixing solution attached to the wall surface of the bubble generation slit 506 is small, the film thickness at the plateau boundary Fa in the bubble generation slit 506 is unlikely to become thin, and bubbles are not easily broken. If the bubble breakage hardly occurs, it is difficult for the bubbles Fb adjacent to each other across the plateau boundary Fa to communicate with each other, and the bubble diameter can be prevented from increasing due to the bubble breakage. For this reason, in the fixing liquid foaming device 500 of the present embodiment, it is possible to suppress the occurrence of unevenness in the bubble diameter distribution caused by the occurrence of bubble breakage in the bubble generation slit 506.

FIG. 14 is an enlarged explanatory view of a part of the foam manifold 503 and the discharge slit 504 indicated by a region β in FIG. FIG. 14A is an explanatory view of the present embodiment, and is an explanatory view of a state in which the foam-like fixing liquid F is passed through the foam manifold 503 and the discharge slit 504 whose wall surfaces have been subjected to liquid repellent processing. FIG. 13B is an explanatory diagram of a comparative example, and is an explanatory diagram of a state in which the foam-like fixing liquid F is passed through the foam manifold 503 and the discharge slit 504 whose wall surfaces are not subjected to liquid repellency.
In FIG. 14, the broken-line arrows in the figure indicate the flow of the foam-like fixing solution F, and the solid-line arrows indicate the flow of the liquid component (fixing solution) that flows out from the plateau boundary Fa of the foam-like fixing solution F. Also, the thicker the solid arrow, the greater the amount of liquid flowing.

  As shown in FIG. 14B, when the foam-like fixing solution F is passed through the foam manifold 503 whose wall surface is not subjected to liquid repellency, the wall surface of the foam manifold 503 from the plateau boundary Fa as indicated by the solid line arrow. The amount of the fixer that spreads wet is increased. The fixer that has spread on the wall surface flows to the end in the width direction along the wall surface of the foam manifold 503. For this reason, the liquid amount of the fixing liquid increases toward the end in the width direction in the foam manifold 503 (left side in FIG. 14). The fixer that has flowed along the wall surface of the foam manifold 503 toward the end in the width direction flows into the discharge slit 504 together with the foamy fixer F that flows into the discharge slit 504. At this time, the fixing solution flowing along the wall surface is mixed with the foam-like fixing solution F in the bubble manifold 503 or the discharge slit 504. Thereby, as shown in FIG. 14 (b), the amount of the fixing solution contained in the foam-like fixing solution F is increased toward the outer side in the width direction, the bulk density is high, and the foam-like fixing solution F having a small bubble diameter is obtained. It is discharged from the foamy fixing solution discharge port 501. Further, the foam-like fixer F that has flowed into the discharge slit 504 from the center in the width direction of the foam manifold 503 (on the right side in FIG. 14) is applied to the wall surface of the bubble transport path until it reaches the discharge slit 504. Unlike the width direction end portion, the liquid amount remains small. Further, the discharge slit 504 has a longer path through which the foam-like fixing liquid F passes toward the center side, and the discharge slit 504 has a narrow flow path width and is easily affected by the wall surface. Inside, the amount of the fixing liquid that spreads from the plateau boundary Fa to the wall surface of the discharge slit 504 increases toward the center. For this reason, the amount of the fixing solution of the foamy fixing solution F is reduced, the bulky fixing solution F having a low bulk density and a large bubble diameter is discharged from the foaming fixing solution discharge port 501. Thus, the bulk density is higher at the width direction end side and becomes a foam-like fixing solution F having a smaller bubble diameter, and the bulk density is lower at the width direction center portion side and becomes a foam-like fixing solution F having a larger bubble diameter. In the foam-like fixer F discharged from the foam-like fixer outlet 501, the bubble diameter distribution and the bulk density distribution are uneven depending on the position in the width direction.

  Further, like the foam-like fixing solution F discharged at the center, the foam-like fixing solution F having a large bubble diameter and a thin film thickness at the plateau boundary Fa is easily broken. Here, if bubbles are broken in a closed space such as in the bubble conveyance path, the bubble diameter of the foam-like fixing solution F only increases. However, if bubbles are broken in the open space as in ejection, bubbles of the bubble-like fixing solution F are produced. Not only does the diameter increase, but the air escapes and part of it becomes the liquid fixer 210. Since the liquid fixing liquid 210 becomes a loss of the fixing liquid, it is necessary to generate a lot of foamy fixing liquid F correspondingly.

  On the other hand, as shown in FIG. 14A, when the foam-like fixing liquid F is passed through the foam manifold 503 whose wall surface has been subjected to liquid repellency, as indicated by the solid line arrow, the foam manifold 503 is separated from the plateau boundary Fa. The amount of the fixer that spreads on the wall surface is smaller than that in the configuration of FIG. The fixer that has spread on the wall surface flows along the wall surface of the foam manifold 503 toward the end in the width direction. However, since the amount of the fixer flowing along the wall surface is small, the fixer F together with the foamy fixer F flowing into the discharge slit 504 is used. The amount of the fixer flowing from the bubble manifold 503 into the discharge slit 504 is reduced. Since there is little movement of the fixing liquid that has flowed through the wall surface of the foam manifold 503, as shown in FIG. 14A, the amount of the fixing liquid contained in the foam-like fixing liquid F is suppressed from increasing toward the outer side in the width direction. It can suppress that a bulk density becomes high. In addition, the foam-like fixer F that has flowed into the discharge slit 504 from the vicinity of the center in the width direction of the foam manifold 503 remains on the wall surface of the bubble transport path until reaching the discharge slit 504. Since the liquid repellent finish is also applied to the wall surface of the bubble conveyance path up to, the decrease in the liquid amount is suppressed. Further, the discharge slit 504 has a longer path through which the foam-like fixing liquid F passes toward the center side. However, the wall surface of the discharge slit 504 is also liquid-repellent. It is possible to suppress wetting and spreading from the plateau boundary Fa to the wall surface of the discharge slit 504. For this reason, even in the central portion of the ejection slit 504, it is possible to suppress a decrease in the amount of the fixing solution of the foam-like fixing solution F, and it is possible to suppress a decrease in bulk density and an increase in the bubble diameter. . As described above, the foam fixing solution F having a high bulk density at the width direction end portion and a small foam diameter is suppressed, and the bulk density is low at the center in the width direction and has a large bubble diameter. Therefore, it is possible to prevent the bubble-like fixer F discharged from the bubble-like fixer discharge port 501 from being uneven in the bubble diameter distribution and the bulk density distribution depending on the position in the width direction. it can.

  Moreover, since it can suppress that the film thickness of the plateau boundary Fa of the foam-like fixing solution F discharged at the center part becomes thin, the foam-like fixing solution F becomes difficult to break when discharging, and bubbles are broken when discharged. It is possible to prevent a part of the fixing solution F from becoming the liquid fixing solution 210. As a result, it is possible to reduce the loss of the fixing liquid resulting from bubble breakage during ejection.

As described above, the fixing liquid foaming device 500 according to the present embodiment makes the foam-like fixing liquid F the liquid-repellent surface by making the wall surface (the wall surface of the foam conveyance path) that the foam-like fixing liquid F inside contacts with the liquid-repellent. The amount of liquid taken away by the wall surface during movement and the amount of liquid flowing along the wall surface can be reduced. As a result, it is possible to suppress an increase in bulk density due to the fixing solution flowing along the wall surface being mixed into the foam-like fixing solution F, and an increase in the diameter of the bubbles due to bubble breaking during conveyance. It is possible to reduce the occurrence of unevenness in the distribution of the bulk density and the distribution of the bubble diameter of the foam-like fixing liquid F supplied to the liquid.
Further, by suppressing bubble breakage of the foam-like fixer F discharged from the central portion in the width direction of the foam-like fixer outlet 501, it is possible to prevent gas escape from causing air to escape from the foam-like fixer F. As a result, the amount of the fixing solution that is lost can be reduced, and the generation efficiency of the foamy fixing solution F is improved.

The fixing liquid foaming device 500 of this embodiment is made of stainless steel, and performs a liquid repellent treatment by applying fluororesin processing to the wall surface forming the foam transport path.
Table 1 shows a comparison of the contact angle with respect to the fixing solution between the surface of the stainless steel subjected to the fluororesin processing and the surface of the stainless steel not subjected to the liquid repellent treatment.

As shown in Table 1, it is understood that the liquid repellency with a contact angle of 60 [°] or more is obtained by applying fluororesin processing to the surface of stainless steel.
In the experiment shown in Table 1, it is made of stainless steel, and the effect has been confirmed with parts made of stainless steel, but in the end, most parts other than the flow path of the foam generating part are made of resin. The resin used is a resin that is not affected by a softening agent such as PET (polyethylene terephthalate) or PEEK (polyetheretherketone), and these resins can be subjected to water repellent treatment having a water repellent effect like stainless steel. .

Here, the liquid repellency of the solid surface with respect to the liquid will be described.
It is effective for improving the liquid repellency of the substrate that the surface free energy of the solid forming the substrate is smaller than the surface energy of the liquid. Specifically, it is advantageous to coat the surface of the substrate with a fluororesin (PTFE, PFA, FEP, etc.) to form a surface layer. It is also known that the liquid repellency and lyophilicity are improved by providing a fine uneven structure on the surface. In other words, by providing a fine concavo-convex structure on the liquid repellent surface, the liquid repellency is further improved, and the lyophilic surface is improved in lyophilicity. As a technique for providing a fine concavo-convex structure, for example, techniques described in JP 2006-83244 A, JP 2005-113110 A, and the like are known.

  In addition, the wall surface of the bubble conveyance path has a liquid repellency, such as a stainless steel and a liquid repellent finish on the surface of a material with a low liquid repellency where the contact angle of the fixing liquid to the surface is less than 60 [°]. It is not restricted to the structure which gives. By using a material that forms a wall surface that exhibits liquid repellency as a material having high liquid repellency with respect to the fixer, the contact angle of the fixer with respect to the surface may be 60 [°] or more. Good.

Further, as shown in FIG. 1, in the fixing device 60 of the present embodiment, each member is arranged so that the foam-like fixing liquid discharge port 501 and the surface of the application roller 61 face each other. For this reason, the foam-like fixing solution F discharged from the foam-like fixing solution outlet 501 is immediately applied to the application roller 61.
Thus, since the foamy fixing solution F is generated immediately before being supplied to the application roller 61, the distance for feeding the foamy fixing solution F is shortened, and a large-capacity pump is required as compared with the conventional fixing solution foaming device. Disappear.
Further, since the once-generated foam fixing solution F deteriorates with time, the foam-like fixing solution F that has passed for a certain period of time after generation must be discharged out of the foam generation system. Therefore, if the distance for feeding the foam-like fixing solution F is long, the volume of the transport path from the position where the initial foaming is performed to the fixing solution supply position increases, and a large amount of the foam-like fixing solution F is discharged after a certain period of time. Will have to do.
In contrast, in the fixing liquid foaming device 500 of the present embodiment, a small amount of foam-like fixing remaining in the internal space of the foam transport path (foam generation slit 506, foam outlet pipe 505, foam manifold 503, and discharge slit 504). It is only necessary to discharge the liquid F, and waste of the liquid fixing liquid 210 can be suppressed. Furthermore, it is possible to suppress the load on the recovery mechanism for recovering the foamy fixing solution F from becoming very large.

  As described above, the fixing solution foaming device 500 of the present embodiment reduces the loss of the foamy fixing solution F by the space-saving fixing solution foaming device, and has a low density and a small particle size foaming fixing solution. F can be generated.

The liquid fixing solution 210 of the fixing device 60 is foamed and used as a foamy fixing solution F, and contains a softening agent, a foaming agent, a foaming agent, a diluent, and the like. If such a liquid fixer 210 is stored for a long time in a state where it can be used as a fixer, the fixer changes over time due to hydrolysis and the like, and the desired fixability and desired foamability are obtained. May not be possible.
When such a fixing solution is used, among the components constituting the fixing solution, components that may be deteriorated over time when mixed are contained in a plurality of different fixing solution constituent solutions, individually stored, and fixed. It is desirable to mix when used as a liquid.

Next, the application roller 61 which is a fixing liquid application unit provided in the fixing device 60 will be described.
As shown in FIG. 1, a fixing liquid foaming device 500 is disposed above the application roller 61, and the application roller 61 is a foam fixing device having a desired microbubble diameter generated by the fixing liquid foaming device 500. Fixing liquid applying means for applying the liquid F to a toner particle layer that forms an unfixed toner image on the transfer paper P.
The fixing device 60 includes a pressure roller 62 at a position facing the application roller 61, and the application roller on the upstream side in the surface movement direction of the application roller 61 with respect to the application position C where the application roller 61 and the pressure roller 62 face each other. A film thickness regulating blade 63 that is close to or in pressure contact with the surface of 61 is provided.
The film thickness regulating blade 63 of the fixing device 60 of the present embodiment is disposed close to the surface of the application roller 61, and the gap width with the application roller 61 can be controlled as will be described in detail later. In this way, by controlling the gap width between the film thickness regulating blade 63 and the application roller 61, the film thickness of the foam-like fixing liquid F on the surface of the application roller 61 can be controlled.

On the surface of the coating roller 61 at the coating position C facing the transfer paper P, there is a film of the foam-like fixing liquid F formed through the portion facing the film thickness regulating blade 63.
In the case where the fixing liquid is applied to the unfixed toner image T, the fixing liquid penetrates the unfixed toner image depending on the fixing environment such as the thickness of the toner layer on the recording medium such as the transfer paper P, the type of the recording medium, and the environmental temperature. Easy to do.
On the other hand, when the width of the fixing nip formed by the pressure roller 62 coming into pressure contact with the application roller 61 and the conveyance speed of the recording medium are constant, the time for the recording medium to pass through the transfer nip is constant. . The toner particles forming the toner image on the recording medium are softened while passing through the fixing nip, and are fixed on the recording medium by being pressurized, so that the toner particles are sufficiently softened while passing through the fixing nip. There is a need.

At this time, by increasing the film thickness of the fixing solution applied to the toner image on the recording medium, the time for the fixing solution to penetrate the toner particles can be shortened. Unnecessary consumption of fixer. Furthermore, even if the fixing solution is foamy and has a low bulk density, if it is applied excessively, the toner particles will be washed away by the excess fixing solution, causing image quality degradation, and fixing solution responsiveness due to a longer drying time of the fixing solution. May cause problems. For this reason, if the fixing conditions allow the fixing solution to easily penetrate into the toner particles, the film thickness of the foam-like fixing solution F on the surface of the application roller 61 is controlled to be thin so that the fixing solution is difficult to penetrate. For example, it is desirable to control so that the film thickness of the foamy fixing solution F on the surface of the application roller 61 is increased.
In the fixing device 60 of this embodiment, the gap width between the film thickness regulating blade 63 and the application roller 61 can be controlled, and the film thickness of the foam-like fixing liquid F on the surface of the application roller 61 can be controlled. The film thickness of the foam-like fixing solution F can be made suitable. Therefore, the film thickness regulating blade 63 forms a film of the foam-like fixing solution F having a film thickness that makes the amount of the fixing solution optimized with respect to the fixing solution penetration time of the layer thickness of the unfixed toner on the transfer paper P. .

  As in the fixing device 60 of the present embodiment, the foamy fixing solution F is applied to the toner layer on the transfer paper P by the application roller 61, thereby preventing the toner particles from being offset on the surface of the application roller 61. Even if the film thickness of the foam-like fixing solution F is applied to the transfer paper P in a state where it is thicker than the resin fine particle layer, the bulk density of the foam-like fixing solution F is extremely low. When the contained bubbles break, it is possible to give a small amount to the resin fine particle layer of the fixing solution containing the softening agent. The foam-like fixer F containing the desired microbubbles generated by the fixer-foaming device 500 is provided between the film-thickness regulating blade 63 and the coating roller 61 from the foam-like fixer outlet 501 or the film thickness. It is dropped on the surface of the application roller 61 on the upstream side in the surface movement direction of the application roller 61 from the position facing the regulation blade 63.

  The pressure roller 62 of the fixing device 60 includes an elastic layer, and an elastic porous body (hereinafter referred to as a sponge) is used as the elastic layer, so that the nip width can be easily changed by changing the applied pressure. Become. Elastic rubber is also suitable instead of sponge, but sponge can be deformed with a weaker force than elastic rubber, and by using sponge as an elastic layer of pressure roller 62, excessive pressure is applied to application roller 61. A long nip width can be secured without increasing the height.

The fixer contains a softening agent that softens or swells the resin component of the toner. For this reason, in the unlikely event that the fixing liquid adheres to the sponge portion of the pressure roller 62, a problem such as softening of the sponge material may occur. Therefore, the resin material of the sponge material is softened or swollen by the softening agent. It is desirable that there is no material.
In order to prevent problems such as softening of the sponge material, the pressure roller 62 may be configured such that the surface of the sponge roller is covered with a flexible film. Even if the sponge material is a material that deteriorates with a softening agent, the pressure roller 62 made of the sponge material can be prevented from being deteriorated by covering the sponge material with a flexible film that does not soften or swell with the softening agent. .
As the sponge material, for example, a porous body of resin such as polyethylene, polypropylene, and polyamide is suitable. Further, as the flexible film covering the sponge, polyethylene terephthalate, polyethylene, polypropylene, tetrafluoroethylene / verfluoroalkyl vinyl ether copolymer (PFA), and the like are suitable.

  In the configuration in which the application roller 61 and the pressure roller 62 of the fixing device 60 shown in FIG. 1 are constantly in contact, the foamy fixing solution F on the surface of the application roller 61 is added when the transfer paper P is not being conveyed. There is a risk of adhering to and fouling the pressure roller 62. In order to prevent such a problem, a paper leading edge detecting means (not shown) for detecting the leading edge of the transfer paper P transported toward the fixing device 60 is provided with a transporting direction of the transfer paper P with respect to the fixing device 60. Provided on the upstream side, foam fixing on the surface of the application roller 61 so that the fixing liquid is applied only from the front end of the transfer paper P to the rear in accordance with a paper front end detection signal generated by the paper front end detection means. It is desirable to form liquid F.

  Further, in the fixing device 60 shown in FIG. 1, the application roller 61 and the sponge pressure roller 62 are separated from each other by a drive mechanism (not shown) during standby, and only in response to the paper leading edge detection signal of the paper leading edge detection means. The application roller 61 and the pressure roller 62 may be brought into contact with each other. In the configuration in which the application roller 61 and the pressure roller 62 are brought into contact with and separated from each other, the trailing edge of the transfer paper P is also detected by the paper leading edge detection means, and the coating roller 61 and the pressure roller 62 are switched according to the paper trailing edge detection signal. It is desirable to perform control to separate them.

In the fixing device 60, by adjusting the gap width between the surface of the coating roller 61 and the surface of the coating roller 61 arranged so as to form a gap with the surface of the coating roller 61, the foamy fixing liquid on the surface of the coating roller 61 is adjusted. The film thickness of F is controlled.
FIG. 15 is a schematic view showing a state in which the film thickness of the foamy fixing solution F on the surface of the application roller 61 is controlled by controlling the position of the film thickness regulating blade 63.
FIG. 15A is an explanatory diagram when the gap width between the coating roller 61 and the film thickness regulating blade 63 is narrowed, and FIG. 15B is the gap width between the coating roller 61 and the film thickness regulating blade 63. It is explanatory drawing when widening.

In the fixing device 60, the end of the film thickness regulating blade 63 opposite to the side close to the application roller 61 is fixed to the blade rotation shaft 63a. The blade rotation shaft 63a is a member that rotates when driving is transmitted from a drive source (not shown), and the rotation of the film thickness regulating blade 63 that rotates together with the blade rotation shaft 63a by controlling the drive of the drive source. Control the position in the direction of movement. In this way, by controlling the position of the film thickness regulating blade 63 in the rotational direction, the gap width between the coating roller 61 and the end of the film thickness regulating blade 63 on the side close to the application roller 61 can be adjusted. it can.
When thinning the foam-like fixing liquid film Fd supplied on the surface of the coating roller 61 and having passed through the portion facing the film thickness regulating blade 63, the gap width is narrowed as shown in FIG. To do. On the other hand, when thickening the foam-like fixing liquid film Fd, the gap width is increased as shown in FIG.
In this way, by controlling the film thickness of the foam-like fixing liquid film Fd, the foam-like fixing liquid film Fd having a film thickness optimum for the thickness of the toner layer of the unfixed toner image on the transfer paper P is converted into the unfixed toner. Can be applied to the image.

As in the fixing device 60, the film thickness regulating blade 63 is controlled so that the film thickness of the foam-like fixing liquid F at the application position C becomes a film thickness suitable for the layer thickness of the toner layer of the unfixed toner image T. In the configuration, the gap width of the film thickness regulating blade 63 is controlled based on image information used in the optical writing device 2.
For example, when the toner image on the transfer paper P to which the foamy fixing liquid F is applied is a full-color image, the thickness of the toner layer of the unfixed toner image T is increased. Control to widen the gap width. On the other hand, in the case of a black single-color image, the thickness of the toner layer of the unfixed toner image T is reduced, so that the gap width of the film thickness regulating blade 63 is controlled to be narrowed.

As the fixing liquid supply pump 200 provided in the fixing device 60 of the present embodiment, a gear pump, a bellows pump, or the like is applicable, but a tube pump is preferable.
If there is a part that constitutes a vibration mechanism or a rotation mechanism in the path through which the fixing liquid passes, such as a gear pump, the liquid may foam in the pump, and the liquid may be compressible and the conveyance capacity may be reduced. There is. Further, if there is a part constituting the mechanism in the path of the fixing liquid, the part or the like may contaminate the fixing liquid or conversely deteriorate the part.

On the other hand, since the tube pump is a mechanism that pushes out the liquid in the tube while deforming the tube, the only member in contact with the fixing liquid is the tube. By using a liquid-resistant member as the tube, There is no contamination or deterioration of pump system parts. In addition, since the conveying force is applied to the liquid passing through the inside simply by deforming the tube, the fixing liquid does not foam, and it is possible to prevent the conveyance capacity from being lowered due to the foaming.
The fixing liquid supply pump 200 is not limited to the above-described various pumps, and may be any pump that has an output capable of applying a pressure necessary for conveying the fixing liquid. Further, in order to prevent internal pressure and flow rate pulsation due to compression, a pump with less pulsating flow equipped with a pressure sensor, a pulse damper and the like is suitable.

The fixing device 60 of the present embodiment uses a blade-like film thickness regulating blade 63 as a foam-like fixing liquid film thickness regulating member. The foam-like fixing liquid film thickness regulating member is not limited to a blade-like member, and the thickness of the foam-like fixing liquid F on the surface of the application roller 61 may be controlled by a wire bar.
Even in the configuration using the wire bar, similarly to the configuration using the film thickness regulating blade 63 described with reference to FIG. 15, the thickness of the foam-like fixing solution F on the surface of the coating roller 61 is controlled by the wire bar, and a desired The thickness is a foam-like fixing liquid film Fd.
The foamy fixing solution F of the fixing device 60 is generated by the above-described fixing solution foaming device 500 and is dropped from the foamed fixing solution discharge port 501 between the film control wire bar and the coating roller 61. By using the wire bar as the foam fixing solution film thickness regulating member, the uniformity of the foam fixing solution film Fd in the axial direction on the surface of the application roller 61 is improved as compared with the configuration using the blade.

[Modification]
Next, a modified example in which the configuration in which the foamy fixing solution F is applied to the transfer paper P is different from the fixing device 60 of the embodiment described with reference to FIG. 1 will be described.
FIG. 16 is a schematic explanatory diagram of a fixing device 60 according to a modification.
The fixing device 60 of the modified example uses a coating belt 65 as a fixing solution application member instead of the application roller 61 of the fixing device 60 of the above-described embodiment, and uses a fixing solution for foaming the unfixed toner image T on the transfer paper P. In this configuration, F is applied. Further, as shown in FIG. 16, the fixing device 60 according to the modification includes a pressure belt 66 instead of the pressure roller 62 of the fixing device 60 of the embodiment.

Also in the fixing device 60 of the modified example, the foamy fixing solution F having a desired bubble diameter is supplied onto the application belt 65 from the foamed fixing solution discharge port 501 of the fixing solution foaming device 500 similar to the above-described embodiment. Is done. The foamy fixing solution F supplied onto the coating belt 65 passes between the film thickness regulating blade 63 and the coating belt 65. At this time, by adjusting the gap width between the film thickness regulating blade 63 and the coating belt 65, the film thickness of the foam-like fixing liquid F on the coating belt 65 can be controlled to an optimum state.
As the coating belt 65, for example, a member such as a seamless nickel belt or a seamless PET film coated with a releasable fluororesin such as PFA can be used.
In the configuration in which a belt-shaped application member is used instead of the roller-shaped application member as in the application belt 65 shown in FIG. 16, the nip width can be easily increased.

The configuration in which the belt member is used as the member for forming the fixing nip for applying the foamy fixing solution F to the transfer paper P is not limited to the configuration shown in FIG.
As shown in the fixing device 60 shown in FIG. 17, the pressure side may be a roller-like pressure roller 62 instead of a belt shape, and a fixing nip may be formed by the application belt 65 and the pressure roller 62.
Further, as in the fixing device 60 shown in FIG. 18, the application side may be the application roller 61, the pressure side may be the pressure belt 66, and the application roller 61 and the pressure belt 66 may form a fixing nip. .

  As in the configuration described with reference to FIGS. 16, 17, and 18, it is possible to easily widen the fixing nip width by using at least one endless moving body on the application side or the pressure side as a belt configuration. Become. As a result, it is possible to avoid applying an excessive force that causes wrinkles on the paper between the members forming the fixing nip. Further, assuming that the time required for the fixing liquid to permeate through the fixing nip, that is, the time for the transfer paper P to pass through the nip is the same, it is possible to move a long distance in the same time. This makes it possible to increase the speed of fixing.

Next, the liquid formulation of the fixing solution will be described.
As described above, the foam-like fixing solution F has a structure in which bubbles are contained in the fixing solution containing the softening agent. The fixing solution preferably contains a foaming agent and a foam-increasing agent in order to stably contain bubbles when foamed and to form a foam that forms a bubble layer having a uniform bubble size as much as possible. Moreover, it is desirable to contain a thickener since the bubbles are more stably dispersed in the liquid when the viscosity is higher to some extent.

As the foaming agent, an anionic surfactant, particularly a fatty acid salt is desirable. Since the fatty acid salt has surface activity, the surface tension of the fixing solution containing water is lowered to facilitate foaming of the fixing solution, and since the fatty acid salt has a layered lamellar structure on the foam surface, the foam wall (plateau boundary Fa) is formed. It is stronger than other surfactants and has extremely high foam stability.
Further, in order to make the foaming property of the fatty acid salt effective, it is desirable that the fixing solution contains water, and the fatty acid is preferably a saturated fatty acid resistant to oxidation from the viewpoint of long-term stability in the air.
However, it is possible to help the solubility and dispersibility of the fatty acid salt in water by containing a slight amount of the unsaturated fatty acid salt in the fixing solution containing the saturated fatty acid salt. Accordingly, it is possible to have excellent foaming properties even in a low temperature environment of 5 [° C.] to 15 [° C.], and stable fixing is possible in a wide environmental temperature range. Further, by containing some unsaturated fatty acid salt in the fixing solution, it is possible to prevent separation of the fatty acid salt in the fixing solution during standing for a long time.

As the fatty acid used in the saturated fatty acid salt, saturated fatty acids having 12, 14, 16, and 18 carbon atoms are suitable, and specific examples include lauric acid, myristic acid, palmitic acid, and stearic acid.
A saturated fatty acid salt having 11 or less carbon atoms has a large odor and is not suitable for a fixing solution used in an image forming apparatus used in offices and homes. Further, a saturated fatty acid salt having 19 or more carbon atoms is not suitable because the solubility in water is lowered and the standing stability of the fixing solution is remarkably lowered.
Saturated fatty acid salts with saturated fatty acids suitable for use as described above are used alone or in combination as a foaming agent.

As the fatty acid salt used for the foaming agent, an unsaturated fatty acid salt may be used, and an unsaturated fatty acid having 18 carbon atoms and 1 to 3 double bonds is desirable. Specifically, oleic acid, linoleic acid, and linolenic acid are suitable. If the unsaturated fatty acid double bond is 4 or more, the reactivity is strong, so that the standing stability of the fixing solution is lowered.
An unsaturated fatty acid salt with an unsaturated saturated fatty acid suitable for these uses is used alone or in combination as a foaming agent. Further, the above-described saturated fatty acid salt and unsaturated fatty acid salt may be mixed and used as a foaming agent.

When the above-described saturated fatty acid salt or the above-mentioned unsaturated fatty acid salt is used as the foaming agent for the fixing solution used in the fixing device 60 of the present embodiment, it is desirable to use a sodium salt, potassium salt or amine salt.
Here, after the power is supplied to the fixing device, it is an important factor as a commercial value of the fixing device that the fixing device can be quickly fixed. In order to be able to fix in the fixing device, it is essential that the fixing solution is in the form of a suitable foam. However, the fatty acid salt described above is quickly foamed so that it can be fixed after the power is turned on. Can be made in a short time. In particular, by using an amine salt, it is possible to easily produce a foam-like fixing solution by foaming in a short time compared to other foaming agents when shear force is applied to the fixing solution. It is possible to create a fixable state in a short time after powering on the apparatus.

  The softening agent that softens the resin by dissolving or swelling it contains an aliphatic ester. This aliphatic ester is excellent in solubility or swelling property that dissolves or swells at least a part of the resin contained in the toner or the like.

The fixing of the toner to the recording medium is performed by a device that is frequently used in a sealed environment, and the softening agent remains in the toner even after the toner is fixed to the recording medium. For this reason, it is preferable that the fixing of the toner to the recording medium does not involve generation of a volatile organic compound (VOC) and an unpleasant odor.
That is, it is preferable that the softening agent contained in the fixing liquid does not contain a volatile organic compound (VOC) and a substance causing an unpleasant odor.
Aliphatic esters that can be used as a softening agent have a high boiling point and low volatility compared to generally used organic solvents (toluene, xylene, methyl ethyl ketone, ethyl acetate, etc.) and have no irritating odor. .

As a practical odor measurement scale that can measure odors in office environments, etc. with high accuracy, the odor index (10 × log {until no substance odor can be felt) by the three-point comparison odor bag method, which is a sensory measurement The dilution ratio of the substance}) can be used. The odor index of the aliphatic ester contained in the softening agent is preferably 10 or less. If the odor index is 10 or less, an unpleasant odor will not be felt in a normal office environment.
In addition, not only the softening agent but also other liquid agents contained in the fixing solution preferably have no unpleasant odor and irritating odor.

  In the fixing solution used in the fixing device 60 of the present embodiment, the aliphatic ester described above preferably includes a saturated aliphatic ester. This is because when the aliphatic ester contains a saturated aliphatic ester, the storage stability (resistance to oxidation, hydrolysis, etc.) of the softener can be improved. Also, many saturated aliphatic esters can dissolve or swell the resin contained in the toner within 1 second. Furthermore, the saturated aliphatic ester can reduce the stickiness of the toner provided on the recording medium. This is considered to be because the saturated aliphatic ester forms an oil film on the surface of the dissolved or swollen toner.

Therefore, as the fixing solution, it is desirable to use a solution in which the saturated aliphatic ester contains a compound represented by the general formula “R1COOR2”.
R1 in the general formula of this compound represents an alkyl group having 11 to 14 carbon atoms, and R2 represents a linear or branched alkyl group having 1 to 6 carbon atoms.
If the number of carbon atoms in R1 and R2 is less than the desired range, odor is generated, and if it is greater than the desired range, the resin softening ability is lowered.
For this reason, the use of the fixing solution containing a compound represented by the general formula “R1COOR2” as the saturated aliphatic ester can improve the solubility or swelling of the resin contained in the toner. In addition, the odor index of the compound represented by the general formula “R1COOR2” is 10 or less, and does not have an unpleasant odor or an irritating odor.

  Examples of the aliphatic monocarboxylic acid ester which is a compound represented by the above general formula “R1COOR2” include ethyl laurate, hexyl laurate, ethyl tridecylate, isopropyl tridecylate, ethyl myristate, isopropyl myristate, and the like. It is done. Many of these aliphatic monocarboxylic acid esters, which are compounds represented by the above general formula “R1COOR2”, are soluble in oily solvents but not in water. Therefore, for many of the aliphatic monocarboxylic acid esters that are compounds represented by the above general formula “R1COOR2”, when an aqueous solvent is used, glycols are contained in the fixing solution as a dissolution aid, and dissolved or microcrystalline. Emulsion form.

Further, as the fixing solution, it is desirable to use a solution in which the aliphatic ester contains an aliphatic dicarboxylic acid ester. When the aliphatic ester contains an aliphatic dicarboxylic acid ester, the resin contained in the toner can be dissolved or swollen in a shorter time.
For example, in high-speed printing of about 60 [ppm], it is desirable that the time required for applying the fixing liquid to the unfixed toner on the recording medium and fixing the toner on the recording medium is within 1 [second]. When the aliphatic ester contains an aliphatic dicarboxylic acid ester, a time required for fixing the toner on the recording medium by applying a fixing solution to the unfixed toner or the like on the recording medium is 0.1 [second. ] Within. Furthermore, since the resin contained in the toner can be dissolved or swollen by adding a smaller amount of the softening agent, the content of the softening agent contained in the fixing liquid can be reduced.

Therefore, as the fixing solution, it is desirable to use a fixing liquid containing the compound represented by the general formula “R3 (COOR4) ₂ ”. R3 in the general formula of this compound represents an alkylene group having 3 to 8 carbon atoms, and R4 represents a linear or branched alkyl group having 3 to 5 carbon atoms. If the number of carbon atoms in R3 and R4 is less than the desired range, odor is generated, and if it is greater than the desired range, the resin softening ability decreases.
As the fixing solution, the aliphatic dicarboxylic acid ester containing a compound represented by the general formula “R3 (COOR4) ₂ ” is used to improve the solubility or swellability of the resin contained in the toner. Can do. In addition, the odor index of the compound represented by the general formula of “R3 (COOR4) ₂ ” is 10 or less, and does not have an unpleasant odor or an irritating odor.

Examples of the aliphatic dicarboxylic acid ester which is a compound represented by the general formula “R3 (COOR4) ₂ ” include, for example, 2-ethylhexyl succinate, dibutyl adipate, diisobutyl adipate, diisopropyl adipate, diisodecyl adipate, sebacic acid Examples include diethyl and dibutyl sebacate. Many of these aliphatic dicarboxylic acid esters, which are compounds represented by the general formula of “R3 (COOR4) ₂ ”, are soluble in oily solvents but not in water. Therefore, when an aqueous solvent is used, glycols are contained in the fixing solution as a dissolution aid and are in the form of a solution or microemulsion.

  Furthermore, in the fixing solution used in the fixing device 60 of the present embodiment, the aliphatic ester preferably contains an aliphatic dicarboxylic acid dialkoxyalkyl. When the aliphatic ester contains an aliphatic dicarboxylate dialkoxyalkyl, the fixability of the toner to the recording medium can be improved.

As the fixing solution used in the fixing device 60 of the present embodiment, it is desirable to use a solution in which the aliphatic dicarboxylate dialkoxyalkyl contains a compound represented by the general formula “R5 (COOR6-O—R7) ₂ ”. . R5 in the general formula of this compound represents an alkylene group having 2 to 8 carbon atoms, R6 represents an alkylene group having 2 to 4 carbon atoms, and R7 represents 1 to 4 carbon atoms. The alkyl group is shown. If the number of carbon atoms in R5, R6, and R7 is less than the desired range, odor is generated, and if it is greater than the desired range, the resin softening ability decreases.

As the fixing solution, a solution in which the aliphatic dicarboxylate dialkoxyalkyl contains a compound represented by the general formula “R5 (COOR6-O-R7) ₂ ” is used. Swellability can be improved. Further, the odor index of the compound represented by the general formula of R5 (COOR6-O-R7) ₂ "is 10 or less, and it does not have an unpleasant odor or an irritating odor.

Examples of the aliphatic dicarboxylic acid dialkoxyalkyl which is a compound represented by the general formula R5 (COOR6-O-R7) ₂ "include, for example, diethoxyethyl succinate, dibutoxyethyl succinate, diethoxyethyl adipate, Examples include dibutoxyethyl adipate and diethoxyethyl sebacate. When these aliphatic dicarboxylic acid dialkoxyalkyls are used in an aqueous solvent, glycols are contained in the fixing solution as a solubilizing agent to be dissolved or in the form of a microemulsion.

  Moreover, although it is not a fatty acid ester, a citric acid ester, ethylene carbonate, and propylene carbonate can also be used as a softening or swelling agent.

  By the way, in the foam-like fixing solution, if the foam-like fixing solution breaks before reaching the application position, a problem similar to the configuration in which the liquid fixing solution is applied occurs. Therefore, there is a demand for a foam having excellent foam stability so that the generated foam-like fixing solution can reach the application position in the form of foam. For this reason, it is desirable to contain a fatty acid alkanolamide (1: 1) type in the fixing solution. Fatty acid alkanolamides include (1: 1) type and (1: 2) type, but it was found that (1: 1) type is suitable for foam stability in the present invention.

The fixing solution contains a softening agent, and this softening agent generally has a strong antifoaming action. For this reason, when the liquid fixing solution is used as the foamy fixing solution as in the fixing device 60 of the present embodiment, the higher the concentration of the softening agent in the fixing solution, the more the foaming property and foam stability of the fixing solution. There is a risk that foaming will be difficult and foaming will be difficult, or the foam-like fixing solution will be liable to break. If it is difficult to foam, it is impossible to obtain a foam fixing solution having a low bulk density. Even if a foam fixing solution having a desired bulk density is obtained, if the foam fixing solution easily breaks, it is This causes the same problem as the configuration in which the liquid fixer is applied.
In addition, as a foaming agent, an anionic surfactant can achieve excellent foaming properties and foam stability, and is excellent as a foaming agent. Among anionic surfactants, fatty acid salts are most excellent in foam stability and are most suitable as a foaming agent for fixing solutions.

In order to solve the problem of deterioration of foamability and foam stability when the softener concentration in the fixing solution is increased, the present inventors have made various prototypes based on the type and concentration of the anionic surfactant. It was. Further, a prototype was made by paying attention to a technique called “super fat” described in Non-Patent Document 1, that is, a free fatty acid contained in a solid detergent (soap).
Here, to outline the technology called super fat, it is a method of adding a small amount of free fatty acids that are difficult to oxidize to increase the excess fat and oil, leaving a small amount of fat and oil that is not saponified, for example, to enhance the moisturizing action, etc. It is said to be effective. In Non-Patent Document 1, it is known that when a very small amount of fatty acid is added to a soap water-based system, the foaming performance is improved and the foam quality becomes more creamy, which is called super fat soap. It is described. Similar to this super fat, an attempt was made to foam by adding a very small amount of fatty acid to a fixing solution having a softening agent, but both foamability and foam stability were poor.

On the other hand, the present inventors use a fatty acid salt having 12 to 18 carbon atoms as a foaming agent, and further contain a fatty acid having 12 to 18 carbon atoms in the fixing solution, thereby increasing the concentration of the softening agent. The present inventors have found that it is possible to provide a foamy fixing solution that does not deteriorate the foamability of the fixing solution.
In the fixing solution containing the softening agent, the number of carbon atoms of the fatty acid salt is excellent in foaming property as compared with the case where water is simply foamed. Specifically, laurate (12 carbon atoms), myristate (14 carbon atoms), palmitate (16 carbon atoms), and stearate (18 carbon atoms) are suitable. Further, pentadecylic acid (carbon number 15), margaric acid (carbon number 17), and the like are also suitable.

  Here, the action of the fatty acid and the softening agent will be described. The softening agent has an ester group in the chemical structure, and the fatty acid has a carbonyl group in the chemical structure. From this point, the ester group of the softener and the carbonyl group of the fatty acid show an electrical action in the fixing solution system, and this causes a binding action between molecules, and the fixing solution is characterized by foaming properties and Improves foam stability.

  Even in the range of 12 to 18 carbon atoms, the smaller the number of carbons, the better the foaming property, but the foam stability is poor, and the larger the number of carbons, the less foaming properties, but the foam stability is extremely excellent. ing. For this reason, a single fatty acid salt may be contained in the fixing solution, but it is more excellent to mix and contain a fatty acid salt having 12 to 18 carbon atoms. As a mixing ratio, it is desirable to contain the most myristic acid salt (14 carbon atoms) and to lower the ratio of lauric acid salt (12 carbon atoms) and stearic acid salt. More specific fatty acid salt ratios are 0: 6: 3: 1, 1: 5: 3: 1, 1: 4 by weight ratio of laurate: myristate: palmitate: stearate. : 4: 1 is suitable.

  By the way, by containing the fatty acid having the same carbon number as the fatty acid salt as the foaming agent in the fixing solution, the foaming property and foam stability can be maintained even when the concentration of the softening agent is increased. If the concentration of the softening agent is less than 10 [wt%], there is no problem in foaming properties even if no fatty acid is contained. However, when the concentration of the softening agent is 10 [wt%] or more, particularly when the concentration of the softening agent is 30 [wt%] or more, only the fatty acid salt is hardly foamed and the foamability is deteriorated. In the fixing solution in which the concentration of the softening agent is 30 [wt%], when the fatty acid having the same carbon number as the fatty acid salt is contained, the foaming property can be maintained.

  However, if the fatty acid content is too high, the ratio of the fatty acid salt, which is a foaming agent, decreases, and the foamability deteriorates again. Therefore, it is better to make the number of moles of fatty acid salt the same as or larger than the number of moles of fatty acid. Or when the ratio of a fatty acid and a fatty acid salt is in the range of 5: 5 to 1: 9, the foamability is excellent.

  In addition to the combination of fatty acid and fatty acid salt having the same carbon number, for example, the fatty acid salt is amine myristate, the fatty acid is stearic acid, the fatty acid salt is potassium palmitate, and the fatty acid is stearic acid. Different combinations in the range of 12 to 18 may be used. In short, by containing a fatty acid having 12 to 18 carbon atoms in the fixing solution, even if a high-concentration softening agent is contained, the foamability is not deteriorated, the foam stability is excellent, and the bulk density is extremely high. Allows low foaming.

  In addition, even if the fixing solution contains a fatty acid having 12 to 18 carbon atoms using other anionic surfactants such as alkyl ether sulfate (AES) as a foaming agent, the foaming property due to an increase in the concentration of the softener It turns out that it is effective in preventing it from getting worse. However, the best combination is a combination with a fatty acid salt.

  Furthermore, fatty acid sodium, fatty acid potassium, and fatty acid amine are suitable as the fatty acid salt. Furthermore, the most suitable fatty acid amine is specifically prepared by heating water, adding a fatty acid, and then adding triethanolamine, followed by heating and stirring for a certain period of time for a saponification reaction. be able to. At this time, by increasing the molar ratio of fatty acid to triethanolamine in the range of 1: 0.5 to 1: 0.9 and the fatty acid ratio, unreacted fatty acid remains after saponification, and the fixing solution Fatty acid and fatty acid amine can be mixed therein. The same is possible with sodium and potassium salts.

  By the way, when the concentration of the softening agent in the fixing solution increases, the softening agent becomes difficult to dissolve in water as a dilution solvent. Therefore, as a result of investigation, by adding polyhydric alcohols, specifically ethylene glycol, diethylene glycol, propylene glycol, 1,3 butylene glycol, glycerin, etc., in the fixing solution, the softener can be dissolved even at a high concentration. And it was found that the foaming property by the fatty acid salt was not deteriorated, but rather the foaming property was improved. The content of the polyhydric alcohol is suitably in the range of 1 [wt%] to 30 [wt%]. If the content is more than 30 [wt%], the foamability is rather deteriorated, which is not suitable.

The fine particles containing the resin to be fixed are not limited to toner, and any fine particles containing resin may be used. For example, resin-containing fine particles containing a conductive member may be used. Further, the recording medium is not limited to transfer paper, and may be any of metal, resin, ceramics and the like. However, it is desirable that the fixer application target is permeable to the fixer, and if the substrate to which the fixer is to be applied is not liquid permeable, the fixer application target having a liquid permeable layer on the substrate is preferable. The form of the recording medium when the fixing liquid application target is a recording medium is not limited to a sheet, and may be a three-dimensional object having a flat surface and a curved surface.
In addition, the present invention can also be applied to applications in which transparent resin fine particles are uniformly fixed on an object to which a fixing solution is applied such as paper and the paper surface is protected (so-called varnish coating).

Among the fine particles containing the resin, the toner used in the electrophotographic process has the highest fixing effect in combination with the fixing solution of the fixing device 60 of the present embodiment. The toner contains a colorant, a charge control agent, and a resin such as a binder resin and a release agent. The resin contained in the toner is not particularly limited, but examples of suitable binder resins include polystyrene resins, styrene-acrylic copolymer resins, and polyester resins. Examples of the mold release agent include wax components such as carbanau wax and polyethylene.
The toner may contain a known colorant, charge control agent, fluidity-imparting agent, external additive and the like in addition to the binder resin. Further, the toner is preferably subjected to a water repellency treatment by fixing hydrophobic fine particles such as hydrophobic silica having a methyl group and hydrophobic titanium oxide to the surface of the toner particles. Among the fixing liquid application targets, the recording medium is not particularly limited, and examples thereof include paper, cloth, and a plastic film such as an OHP sheet having a liquid permeable layer. The oiliness in the present invention means the property that the solubility in water at room temperature (20 [° C.]) is 0.1 [wt%] or less.

  Further, it is desirable that the foamed fixing solution has sufficient affinity for the water-repellent treated toner particles. Here, affinity means the degree of extended wetting of the liquid with respect to the surface of the solid when the liquid comes into contact with the solid. That is, it is preferable that the foamed fixing solution exhibits sufficient wettability with respect to the water-repellent treated toner. The surface of the toner subjected to water repellency treatment with hydrophobic fine particles such as hydrophobic silica and hydrophobic titanium oxide is covered with methyl groups present on the surface of hydrophobic silica or hydrophobic titanium oxide, and is approximately 20 [mN / M] surface energy. Actually, since the entire surface of the water-repellent treated toner is not completely covered with hydrophobic fine particles, the surface energy of the water-repellent treated toner is approximately 20 to 30 [mN / m]. It is guessed. Therefore, in order to have an affinity for the water-repellent toner (having sufficient wettability), the surface tension of the foamed fixing solution is preferably 20 to 30 [mN / m].

When using an aqueous solvent, it is preferable to add a surfactant to make the surface tension 20-30 [mN / m]. In the case of an aqueous solvent, it is desirable to contain a unit price or a polyhydric alcohol. These materials have the advantage of increasing the stability of bubbles in the foam-like fixing solution and making it difficult to break the bubbles. For example, monohydric alcohols such as cetanol, and polyhydric alcohols such as glycerin, propylene glycol, and 1,3 butylene glycol are desirable. Further, by containing these unit price or polyhydric alcohols, it is effective in preventing curling of a recording medium having water absorbency such as paper.
It is also desirable to form an O / W emulsion or a W / O emulsion containing an oil component in order to improve the permeability in the fixing solution and prevent curling of a recording medium such as paper. Desirable agents include sorbitan fatty acid esters such as sorbitan monooleate, sorbitan monosterate, and sorbitan sesquiolate, and sucrose esters such as sucrose laurate and sucrose stearate.

  As a method for dissolving the softener or dispersing the microemulsion in the fixing solution, for example, mechanical stirring means such as a homomixer or a homogenizer using a rotary blade, and vibration such as an ultrasonic homogenizer is applied. Means are mentioned. In any case, a strong shear stress is added to the softener in the fixing solution to dissolve or disperse the microemulsion.

Further, as the fixing device 60, after supplying the foamy fixing solution F to the toner at the application position C, the toner dissolved or swollen by a component (softening agent) that dissolves or swells at least a part of the resin contained in the toner is used. You may provide a pair of smoothing roller (hard roller) to pressurize.
By applying pressure to the dissolved or swollen toner using a pair of smoothing rollers (hard rollers), it is possible to smooth the surface of the toner layer and to give gloss to the surface of the toner layer after fixing. Become. Further, the toner fixability to the recording medium can be improved by pushing the dissolved or swollen toner into the recording medium.

  As described above, the fixing liquid foaming device 500 included in the fixing device 60 of the present embodiment is supplied from the liquid fixing liquid 210 supplied from the fixing liquid supply pump 200 that is a liquid supply means and the air pump 300 that is a gas supply means. A foam generation unit 502 that generates a foamy fixing solution F by mixing air, and a foamy fixing solution discharge port 501 that discharges the foamy fixing solution F generated by the foam generation unit 502 to the outside of the apparatus. It is a generation device. In such a fixing liquid foaming device 500, a foam transport path (foam generation slit 506, foam outlet pipe 505, foam) through which the foamy fixing liquid F passes between the foam generation unit 502 and the foamy fixing liquid discharge port 501. The wall surface forming the manifold 503 and the discharge slit 504) has a liquid repellency with respect to the liquid fixing solution 210. With such a configuration, it is possible to suppress the liquid component of the foam-like fixing liquid F in contact with the wall surface forming the foam conveyance path from spreading. Therefore, it is possible to suppress the occurrence of problems due to the liquid component contained in the foam-like fixing liquid F getting wet on the wall surface forming the foam transport path.

  Further, in the fixing liquid foaming device 500, liquid repellency processing is performed by fluororesin processing on the wall surface of the bubble conveyance path having liquid repellency with respect to the liquid fixing liquid 210. As described above, by performing the liquid repellent processing, the desired liquid repellency can be obtained even if the material itself forming the gas supply path has insufficient liquid repellency.

  In the fixer foaming device 500, the contact angle of the liquid fixer 210 with respect to the wall surface of the bubble transport path having liquid repellency with respect to the liquid fixer 210 is 60 [°] or more. Thereby, the liquid repellency which can suppress that the liquid component in the foam-like fixing liquid F is taken on the wall surface of a foam conveyance path can be obtained.

  Further, in the fixing liquid foaming device 500, the foam generation slit 506, which is a mixing part of the air and the liquid fixing liquid 210 in the foam generation unit 502, is formed by surrounding a gap between two opposing wall surfaces facing each other with a side wall surface. This is a thin layered space having a slit width Ws of 100 [μm]. In addition, the air supply port that connects the gas flow path 350 through which air supplied from the air pump 300 toward the bubble generation unit 502 passes to the bubble generation slit 506 includes a plurality of minute through holes. While supplying the liquid fixing solution 210 from the fixing solution supply port to the thin-layered space, the air is supplied from the air supply port composed of a plurality of minute through holes, so that the bubble-shaped fixing solution F having a simple structure and a small bubble diameter is provided. Can be generated.

  Further, in the fixing liquid foaming device 500, the air supply port has a plurality of minute penetrations in a direction (longitudinal direction) perpendicular to the thickness direction (slit width direction) of the gap between the two opposing wall surfaces forming the foam generation slit 506. It is the shape formed in the side wall surface so that a hole may be located in a line. Further, the fixing liquid supply port that connects the liquid flow path 250, which is the fixing liquid supply path through which the liquid fixing liquid 210 supplied from the fixing liquid supply pump 200 toward the bubble generation unit 502 passes, to the bubble generation slit 506 is long. These are a plurality of minute through holes formed between the air supply ports adjacent in the scale direction. In this manner, the fixing liquid supply port and the air supply port are alternately arranged at one end of the bubble generation slit 506 along the longitudinal direction of the cross section of the bubble generation slit 506, so that the foamy fixing solution F having a small bubble diameter is provided. Can be generated.

  The fixing device 60 of the present embodiment is a foam-like liquid in which bubbles are dispersed in a liquid fixing solution 210 containing a softening agent that softens the toner by dissolving or swelling at least a part of the resin of the toner composed of resin fine particles. A fixing liquid foaming device 500 which is a fixing liquid foaming means to be the fixing liquid F, a fixing liquid supply pump 200 which is a fixing liquid supply means for supplying the liquid fixing liquid 210 to the fixing liquid foaming apparatus 500, and a fixing liquid foaming type. An air pump 300 that is a gas supply unit that supplies air to the image forming apparatus 500, and a fixing solution applying unit that applies a foamy fixing solution F to the surface of the transfer paper P that is a fixing solution application target that carries the unfixed toner image T. Application roller 61. Then, the toner layer that forms the softened unfixed toner image T by applying the foamy fixing solution F is fixed to the transfer paper P. Since the fixing liquid foaming device 500 provided in the fixing device 60 is a foam generating device that generates a fine foam fixing solution F with a small and small bubble diameter and can be made smaller than before, the fixing device No. 60 can realize an appropriate amount of fixing liquid applied to the unfixed toner image T and reduce the size of the apparatus. Further, in the fixing solution foaming device 500 of the present embodiment, the moving distance of the foaming fixing solution F from the initial foaming position to the foaming fixing solution discharge port 501 is short. For this reason, the amount of the foamy fixing solution F discarded after being left for a long time can be reduced, and waste of the fixing solution can be suppressed. Further, the pressure required for transporting the foam fixing solution F, which has a higher fluid resistance than that of a normal liquid, is reduced, and the low-density, small bubble diameter foam fixing solution F is used as an unfixed toner image T. Can be granted. Furthermore, since the fixing liquid foaming device 500 of the present embodiment can suppress the liquid component of the foam fixing liquid F from being taken on the wall surface of the foam transport path, the liquid of the foam fixing liquid F on the wall surface of the foam transport path. It is possible to suppress the occurrence of irregularities in the bulk density and bubble diameter of the foam-like fixing liquid F resulting from the removal of the components. As a result, it is possible to suppress non-uniformity in fixability due to non-uniformity in the bulk density and bubble diameter of the foam-like fixing liquid F applied to the unfixed toner image T on the transfer paper P.

  In addition, the copying machine 100 according to this embodiment includes an image forming unit 3 that is a toner image forming unit that forms a toner image on a transfer paper P that is a recording medium using toner including resin fine particles containing a resin and a colorant. And a fixing unit that fixes the toner image on the transfer paper P, and the fixing unit includes a fixing liquid foaming device 500 that is a foam generating device including the characteristic part of the present invention as the fixing unit. A device 60 is used. Since the fixing device 60 uses a foamy fixing solution, it is possible to stably realize toner offset prevention to the application roller 61 that is a contact applying means at the time of applying contact to the toner layer, and to provide a small amount, and Enables fixing with extremely low power without heating. Further, by using the small fixing liquid foaming device 500, it is possible to reduce the size of the fixing device 60 and the copying machine 100 including the same. Furthermore, the distance of the tubular conveyance path through which the fixing solution in the form of foam passes can be shortened, and the output required for the pump can be suppressed. Furthermore, the amount of the foamy fixing solution F discarded after being left for a long time can be reduced, and waste of the fixing solution can be suppressed. In addition, since unevenness in fixability can be suppressed, final image unevenness can be suppressed and image quality can be improved.

DESCRIPTION OF SYMBOLS 1 Printer part 3 Image formation unit 28 Paper conveyance unit 40 Paper feeding apparatus 50 Document conveyance reading unit 60 Fixing apparatus 61 Coating roller 62 Pressure roller 90 Transfer unit 100 Copying machine 150 Scanner part 200 Fixing liquid supply pump 210 Liquid fixing liquid 220 Fixing Liquid bottle 230 Fixing liquid conveyance pipe 240 Liquid manifold 250 Liquid flow path 300 Air pump 310 Air filter 330 Air conveyance pipe 340 Gas manifold 350 Gas flow path 500 Fixing liquid foaming device 501 Foam fixing liquid discharge port 502 Foam generation part 503 Foam manifold 504 Discharge slit 505 Foam outlet tube 506 Foam generation slit F Foam fixing solution

Japanese Patent No. 3290513 JP 2004-109749 A JP 59-119364 A JP 2004-109747 A JP 2007-219105 A JP 2008-197188 A JP 2010-286816 A

Ishii Ikuo, “Engineering of Bubbles”, first edition, Techno System Co., Ltd., published on March 25, 2005, p. 489

Claims (7)

A foam generating unit that generates a foam liquid by mixing the liquid supplied from the liquid supply unit and the gas supplied from the gas supply unit;
In the foam generating apparatus having a foam discharge port for discharging the foamed liquid generated in the foam generating unit to the outside of the apparatus,
A foam generating apparatus characterized in that at least a part of a wall surface forming a foam transport path through which the foamy liquid passes between the foam generating unit and the foam discharge port has liquid repellency with respect to the liquid. . The foam generating apparatus of claim 1,
A foam generating apparatus, wherein a liquid repellent finish is formed on a wall surface of the foam transport path having liquid repellency with respect to the liquid. The foam generating apparatus according to claim 1 or 2,
The foam generating apparatus according to claim 1, wherein a contact angle of the liquid with respect to a wall surface of the foam transport path having liquid repellency with respect to the liquid is 60 [°] or more. In the foam generating apparatus according to any one of claims 1 to 3,
The liquid and gas mixing part in the bubble generating part is a thin layered space formed by surrounding a gap between two opposing wall surfaces facing each other with a side wall surface,
A gas supply port that connects a gas supply path through which the gas supplied from the gas supply means toward the bubble generation unit passes to the bubble generation unit includes a plurality of minute through holes. Generator. The foam generating apparatus of claim 4,
The gas supply port is formed in the side wall surface so that the plurality of micro through holes are arranged in a direction orthogonal to the thickness direction of the gap between the two opposing wall surfaces,
The liquid supply port connecting the liquid supply path through which the liquid supplied from the liquid supply means toward the bubble generation unit passes to the bubble generation unit is formed between the adjacent gas supply ports. A foam generating device comprising a plurality of minute through holes. A fixing liquid foaming means for forming a liquid fixing liquid containing a softening agent that softens resin fine particles by dissolving or swelling at least a part of the resin into a foamy fixing liquid in which bubbles are dispersed in the liquid;
Fixing solution supply means for supplying the liquid fixing solution to the fixing solution foaming means;
Gas supply means for supplying the gas to the fixer foaming means;
A fixing solution applying means for applying the foamy fixing solution to the surface of the fixing solution application target carrying the resin fine particles;
In a fixing device for fixing the resin fine particles softened by applying the foamy fixing solution to a recording medium,
A fixing device using the foam generating device according to claim 1 as the fixing liquid foaming means. A toner image forming means for forming a toner image on a recording medium using a toner containing resin fine particles containing a resin and a colorant;
Applying a fixing liquid with the surface of the toner image carrier carrying the toner image transferred to the recording medium or the surface of the recording medium carrying the toner image as the surface of the fixing liquid application target;
An image forming apparatus comprising fixing means for fixing the toner image on the recording medium,
An image forming apparatus using the fixing device according to claim 6 as the fixing unit.

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