JP2008203361A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To devise a fixing device so that satisfactory fixing free from fixing failure or feeling of tuck is applied to images different in thicknesses of toner layers on a recording medium as in a color photographic image when a foamed fixing liquid is applied to unfixed toner on the recording medium by the use of a rotatable contact application means. <P>SOLUTION: The fixing device is configured such that a fine resin particle layer 3 containing a coloring material, formed on a recording medium 2, is fixed to the recording medium 2 by a fixing liquid containing a softening agent that softens the fine resin particles by dissolving or swelling at least part of the resin. The fixing device includes: a fixing liquid foaming means 11 for foaming the fixing liquid; a contact application means 20 for applying the foamed fixing liquid to the fine resin particle layer 3 on the recording medium 2; a foamed fixing liquid supply means 12 for supplying the foamed fixing liquid to the contact application means; and a thickness control means for controlling the thickness of the foamed fixing liquid layer on the contact application means. According to the thicknesses of the fine resin particle layer 3 on the recording medium, the thickness of the foamed fixing liquid layer on the contact application means is controlled. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device, a fixing liquid, and an image forming apparatus, and more specifically, a fixing device that fixes resin fine particles (toner) containing a color material onto a recording medium, a fixing liquid used in the fixing device, and the fixing device. The present invention relates to an image forming apparatus to be used.

Image forming apparatuses such as printers, facsimiles, and copiers are apparatuses that form images including characters and symbols on recording media such as paper, cloth, and OHP sheets based on image information. In particular, 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, a heat fixing method is widely used in which toner on a recording medium is heated and melted, and the molten toner is pressurized to fix the toner on the recording medium. Yes. This thermal fixing method is preferably used because it can provide a high fixing speed and high fixed image quality.
However, about half or more of the power consumption in such an electrophotographic image forming apparatus is consumed in heating the toner in the heat fixing method. On the other hand, from the viewpoint of measures against environmental problems in recent years, a fixing device with low power consumption (energy saving) is desired. That is, there is a demand for a fixing method in which the temperature for heating the toner for fixing the toner is extremely lowered than before, or the toner does not need to be heated. In particular, a non-heat fixing method in which the toner is fixed on the recording medium without heating the toner at all is ideal in terms of low power consumption.

As such a non-heat fixing method, for example, an oil-in-water type fixing agent in which an organic compound that can dissolve or swell toner and insoluble or hardly soluble in water is dispersed and mixed in water is used as an unfixed toner. Japanese Patent No. 3,290,513 discloses a wet fixing method for toner in which toner is dissolved or swollen by spraying or dripping from the surface of the fixing object disposed at a predetermined position to dry the fixing object. ("Toner Wet Fixing Method", Patent Document 1).
However, in the wet fixing method of Patent Document 1, since an oil-in-water type fixing agent in which an organic compound insoluble or hardly soluble in water is dispersed and mixed in water is used, a large amount of fixing agent is not fixed. When applied to toner, a recording medium (fixed material) such as transfer paper absorbs moisture of the fixing agent, 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 agent applied to the recording medium by evaporating a large amount of water contained in the fixing agent using a drying device, 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. As one of them, Japanese Patent Application Laid-Open No. 2004-109749 (“Image Forming Apparatus”, Patent Document 2) discloses an aliphatic dibasic acid ester containing a material that dissolves or swells a resin component constituting a toner. A fixing solution diluted (dissolved) with nonvolatile dimethyl silicone has been proposed as a diluent (solvent). Japanese Patent Laid-Open No. 59-119364 (“Fixing Solution and Fixing Method for Unfixed Toner Image”, Patent Document 3) clearly and undisturbed an unfixed image formed by an electrostatic method. As a fixing solution that can be used in a fixing method that can be easily fixed on an image receiving sheet, 8 to 120 parts by volume of silicone oil is mixed with 100 parts by volume of a solvent that dissolves toner and is compatible with silicone oil. A solution for fixing an unfixed toner image in a compatible state has been proposed. 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-processed unfixed toner, The toner can be fixed on the recording medium.

In Japanese Patent Laid-Open No. 2006-323196 (“Fixing Liquid Application Device and Image Forming Apparatus”, Patent Document 4), in the configuration in which the fixing liquid is contacted and applied to the dry toner on the recording medium or the intermediate transfer member, It has been proposed to detect the size and change the fixing liquid application area according to the detection result. When the fixing liquid is applied to the fixing liquid contact applying means other than the width of the recording medium, for example, the plain paper, the fixing device may be contaminated with the fixing liquid. Depending on the size of the recording medium, the normal paper may be used. However, it is an important problem to provide a mechanism for changing the coating area so as to apply the fixer only.
However, in this prior art, as a specific fixing liquid application region changing means, a plurality of application rollers having different lengths in the longitudinal direction are used, or a longitudinal direction in which the fixing liquid is supplied to the application roller can be separated and contacted In this configuration, a plurality of supply rollers having different lengths are used. In these techniques, a plurality of rollers corresponding to the size of the recording medium are required, and it is not easy to reduce the size of the fixing unit. In addition, even in the recording medium, waste of the fixing liquid due to application to the blank portion cannot be prevented.

Japanese Laid-Open Patent Publication No. 2006-163083 (“Image Forming Apparatus”, Patent Document 5) proposes that the non-image portion reduces the amount of fixing liquid per unit area less than the image portion. . The purpose is to prevent the curling and wrinkling of the recording medium such as paper and to reduce the amount of the fixing liquid used by suppressing the amount of the fixing liquid applied to the blank portion which is a non-image portion of the recording medium such as paper. That is.
However, when the thickness of the toner layer on the recording medium is thicker than that of a monochromatic image due to the image, as in the case of a color image, in the configuration in which the amount of fixing liquid applied to the non-image area is simply reduced, the entire toner layer is wetted with the fixing liquid. Therefore, it is not always possible to secure the amount of toner applied, and there is a risk of fixing failure. Conversely, if the amount of fixer applied to the image area is adjusted so as to be optimal for the thickness of the thickest toner layer, it will be excessive for the amount of toner in areas where the toner layer is thin, such as single-color images and halftone images. May cause the toner layer to become tacky, and may cause blocking between papers after printing (sticking problems between papers when printing paper is stacked) and image blurring. .

Japanese Patent No. 3,290,513 JP 2004-109749 A JP 59-119364 A JP 2006-323196 A JP 2006-163083 A

  In the present invention, when a foam-like fixing liquid is applied to an unfixed toner on a recording medium using a rotatable contact applying means, an image having a different toner layer thickness on a recording medium such as a color photographic image is applied. It is an object of the present invention to provide a high-performance fixing device and an image forming apparatus by devising a fixing device so that fixing can be performed without occurrence of defective fixing and tackiness. .

(1) A means for solving the above problem (corresponding to claim 1) is to dissolve or swell at least a part of a resin in a resin fine particle layer containing a color material formed on a recording medium. Assuming a fixing device for fixing to a recording medium with a fixing solution containing a softening agent that softens resin fine particles,
Foam-like fixer generating means for forming the fixer into foam, contact-providing means for applying the foam-like fixer to the resin fine particle layer on the recording medium, and supplying the foam-like fixer to the contact-applying means A foam-type fixing liquid supply means; and a thickness control means for controlling the thickness of the foam-type fixing liquid layer on the contact applying means, and the contact applying means according to the thickness of the resin fine particle layer on the recording medium. It is to control the thickness of the upper foam-like fixing liquid layer.
With this configuration, the amount of the foam-like fixer applied can be controlled in accordance with the thickness of the resin fine particle layer containing the color material formed on the recording medium. It is possible to apply a fixing solution suitable for the resin fine particle layer, to suppress the occurrence of fixing failure and tackiness, and to perform good fixing.

(2) In the fixing device, the thickness control means is divided into a plurality of parts in the longitudinal direction of the contact applying means, and the thickness control means is divided according to the thickness of the resin fine particle layer on the recording medium. Every time, the thickness of the foam-like fixing liquid layer on the contact applying means can be controlled. (Corresponding to claim 2)
According to such a configuration, it becomes possible to finely control the application amount of the foam-like fixing liquid in a direction perpendicular to the conveyance direction of the recording medium, and the fixing reliability is improved.

(3) In the fixing device, the thickness of the foam-like fixing liquid layer on the contact applying means by the thickness control means is controlled from the foam-like fixing liquid supply means according to the thickness of the resin fine particle layer on the recording medium. This can be done by controlling the supply amount. (Corresponding to claim 3)
According to such a configuration, it is possible to control the application amount of the foam-like fixing liquid without providing a mechanically complicated mechanism, and the size of the fixing device can be easily reduced.

(4) In the fixing device, a plurality of foam-like fixing liquid supply means are arranged in a direction perpendicular to the conveyance direction of the recording medium, and the thickness of the foam-like fixing liquid layer on the contact applying means is controlled. Depending on the thickness of the resin fine particle layer on the recording medium, each foam-like fixing liquid supply means can be turned on / off individually. (Corresponding to claim 4)
According to such a configuration, each foam-like fixing liquid supply means can be separately controlled by being turned on / off individually, so that it is easy to downsize and highly reliable fixing. Can be done.

(5) Further, in the above-described fixing device, it is preferable that the contact imparting unit is divided into blocks by a partition plate in the longitudinal direction, and the supply amount of the foam-like fixing liquid is controlled for each block. (Corresponding to claim 5)
According to such a configuration, by providing the partition plate, the foam-like fixing liquid does not leak to other blocks in the longitudinal direction of the contact applying means, and the thickness control reliability of the foam-like fixing liquid layer on the contact applying means is reliable. Is further improved.

(6) In the fixing device, the thickness control unit is divided into a plurality of parts in the longitudinal direction of the contact applying unit and is arranged according to the width of the recording medium or the image width of the resin fine particle layer on the recording medium. Thus, the thickness of the foam-like fixing liquid layer on the contact applying means can be changed by individually controlling. (Corresponding to claim 6)
According to such a configuration, since the plurality of controls can be performed individually and simultaneously by the thickness control means arranged in a plurality of parts, it is possible to accurately control the film thickness of the foam-like fixing liquid. Become.

(7) Further, in the fixing device, the foam-like fixing liquid layer on the contact applying unit is adjusted in accordance with the thickness of the maximum resin fine particle layer for each of the blocks divided in the longitudinal direction of the contact applying unit. The thickness can be controlled. (Corresponding to claim 7)
According to such a configuration, the resin fine particle layer on the recording medium can be reliably fixed for each of the control blocks divided into a plurality.

(8) The fixing solution used in the fixing device according to the present invention contains water, a fatty acid salt, and a softening agent. (Corresponding to claim 8)
According to such a configuration, it is possible to generate a very stable foam-like fixing solution, and it is possible to easily control the thickness of the foam-like fixing solution layer.

(9) In the fixing solution, the fatty acid salt is preferably a sodium salt, a potassium salt, or an amine salt. (Corresponding to claim 9)
According to such a configuration, the excellent foaming property necessary for forming the fixing solution into foam is obtained, and the fixing solution is most suitable for the thickness control means of the foam-like fixing solution layer in the fixing device of the present invention.

(10) In the fixing solution, the softening agent includes a compound represented by the general formula R1COOR2, R1 is an alkyl group having 11 to 14 carbon atoms, and R2 has 1 to 6 carbon atoms. The following alkyl groups are preferable. (Corresponding to claim 10)
With such a configuration, the solubility or swelling property with respect to the resin contained in the toner can be improved.

(11) In the fixing solution, the softening agent includes a compound represented by the general formula R3 (COOR4) 2, R3 is an alkylene group having 3 to 8 carbon atoms, and R4 is a carbon number. Is preferably an alkyl group of 3 or more and 5 or less. (Corresponding to claim 11)
With such a configuration, the solubility or swelling property with respect to the resin contained in the toner can be improved.

(12) In the fixing solution, the softening agent includes a compound represented by the general formula R5 (COOR6-O-R7) 2, wherein R5 is an alkylene group having 2 to 8 carbon atoms, and R6 Is an alkylene group having 2 to 4 carbon atoms, and R 7 is preferably an alkyl group having 1 to 4 carbon atoms. (Corresponding to claim 12)
With such a configuration, the solubility or swelling property with respect to the resin contained in the toner can be improved.

  (13) An image forming apparatus according to the present invention comprises an image forming means for forming an unfixed toner image on a recording medium by an electrostatic recording process using a toner in which resin fine particles contain a color material, and the above fixing device. The toner image is fixed on the recording medium.

The fixing device of the present invention includes a foam-like fixing liquid generating means, a foam-shaped fixing liquid thickness control means, and a contact imparting means. The foam-like fixing liquid generating means generates a foam-like fixing liquid, and has the thickness. The control unit controls the film thickness of the generated foam-like fixing solution on the contact applying unit, and the contact applying unit applies the foam-shaped fixing solution whose thickness is controlled to the resin fine particle layer (toner) on the recording medium. Layer).
As a result, the present invention can achieve a small amount of coating without disturbing the resin fine particles on the recording medium by preventing the offset to the coating member in the contact coating, so that the recording medium such as paper curls. Fixing that is difficult and has excellent fixing response is possible. Furthermore, it is possible to control the application amount of the foam-like fixer according to the thickness of the resin fine particle layer containing the coloring material on the recording medium, and it is possible to perform good fixing without occurrence of fixing failure or tackiness. Is possible.

First, the principle of the present invention will be described with reference to FIGS.
In the present invention, the foam-like (foam-like) liquid containing a large amount of bubbles has a very low bulk density, and the surface tension of the liquid surface, which is a property as a fluid by containing a large amount of bubbles, This invention focuses on the fact that the influence of fluidity is extremely small.

FIG. 1A shows a fixing solution contact applying means of a fixing device using a typical application roller 7. FIG. 1B is a conceptual diagram showing the force acting on the toner particles 3a of the toner layer 3 on the contact surface between the application roller 7 shown in FIG. 1A and the recording medium 2 such as paper. . As shown in FIG. 1B, when the fixing liquid 5 is in a liquid form, a strong surface tension acts on the liquid surface of the fixing liquid 5 on the application roller 7 along the surface of the application roller. (The direction in which the surface tension works is indicated as A). Further, an internal flow B is generated in the moving direction of the application roller 7 inside the fixing liquid layer on the application roller 7.
For this reason, when the thickness of the fixing liquid layer on the coating roller 7 is a thin layer equal to or less than that of the toner layer 3, the surface tension is set so as to pull the unfixed toner particles 3 a onto the surface of the coating roller 7. In addition, the internal flow B also works to carry the toner particles 3a along the surface of the application roller, so that the unfixed toner particles 3a adhere to the application roller 7 and the toner offset 4 is generated. As the fixing liquid layer on the application roller 7 becomes more than twice as thick as the toner layer 3, the influence of the surface tension of the liquid and the internal flow B hardly reaches the toner layer 3. When the layer is thick, the toner offset 4 is reduced. On the contrary, it means that it is necessary to thicken the fixing liquid layer to some extent on the surface of the application roller 7 for uniform application in which the resin fine particles are not offset.

On the other hand, the smaller the amount of the fixing solution on the toner layer 3 on the recording medium 2 after the fixing solution 5 is applied, the better the fixing responsiveness, the remaining liquid feeling and the curling prevention. This means that it is desirable that the weight of the fixing solution is small. When applying, in order to satisfy the condition that the thickness of the fixing solution layer is large and the volume is large and the weight of the fixing solution 5 on the recording medium 2 is small after the application, the density of the fixing solution 5 should be low. Good. Thereby, even if the volume is large at the time of application, the substantial application weight can be reduced.
As shown in FIG. 2, if the fixing solution 5f is formed in a foam form and sufficiently incorporates air, the fixing solution 5f having a low bulk density (the value obtained by dividing the weight of the fixing solution by its volume) is used. Even if the thickness of the fixing liquid layer on the coating roller 7 is large and the volume is large, the bulk density is low, so that the substantial mass of the fixing liquid adhering to the recording medium 2 such as paper can be reduced, and the toner offset. 4 can be applied to the recording medium 2 in a small amount without the occurrence of 4, and the object of the present invention can be achieved.

FIG. 3 is a schematic view showing a layer configuration example of the foam-like fixing solution 5f at the time of application in the present invention. The fixing solution 5f shown in the figure has a foam-like configuration containing a softening agent, water, a fatty acid salt as a foaming agent, and bubbles 5b in the liquid. Thus, the bulk density of the fixing solution 5f can be extremely reduced by containing a large amount of the bubbles 5b. Reference numeral 5p represents a plateau boundary (liquid).
With this configuration, as shown in FIG. 4 (a), even when the fixer 5f is applied in a large volume, the bulk density is low and the application weight is small, so that bubbles are broken after that. Once foamed, the substantial coating amount can be extremely reduced as shown in FIG. In the present invention, the “foam shape” means a state in which a large amount of bubbles are dispersed in the liquid and the liquid is compressible.

Cell content in the foamed fixer 5f may vary depending on the thickness of the bulk density and the coating layer, generally, as the bulk ^{density, 0.01g / cm 3 ~0.1g / cm} 3 range of about desirable . Further, the foam-like fixing solution composed of a cellular layer means a foam-shaped fixing solution composed of a single layer or a plurality of cellular layers, and does not necessarily have a clear layer surface.
Furthermore, the foam-like fixing solution 5f only needs to be in the form of foam when applied to the resin fine particle layer on the recording medium, and does not need to be in the form of a foam in the storage container. In the storage container, it is a liquid that does not contain bubbles, and it is desirable to provide a means for forming a foam in the liquid supply path from when the liquid is supplied from the container to when it is applied to the resin fine particle layer. This is because it is a liquid in the storage container, and the configuration in the form of a foam after the liquid is taken out from the container has a great advantage that the container can be downsized.

[Fixing device]
Next, the fixing device of the present invention will be described with reference to FIG. FIG. 5 is a schematic view of the fixing device, and shows a state in which the foam-like fixing liquid is applied by the application roller of the contact applying means.
As shown in FIG. 5, the fixing device includes a foam-like fixing solution generating means 11 for foaming a fixing solution by stirring or the like, and a tube for supplying the formed fixing solution. A film that controls the film thickness of the foam-like fixing liquid layer by forming a minute gap between the supply means 12, the stirring roller 15 for making the foam-like fixing liquid uniform on the application roller 17, and the application roller 17. A thickness control blade 16 and a contact applying means 20 including an application roller 17 and a pressure roller 18 are provided.

The fixing solution formed into foam in the foam-like fixing solution generating means 11 is sent to the supply port 13 of the supply means 12 and supplied onto the application roller 17, and is made uniform by the stirring roller 15 on the application roller 17. The foam-like fixing liquid on the application roller 17 has a constant film thickness by passing through a minute gap between the application roller 17 and the film thickness control blade 16. The foam-like fixing liquid having a uniform and constant film thickness is applied to the unfixed resin fine particle layer (toner layer) 3 on the recording medium 2 by the coating roller 17, and the resin fine particles (toner) are applied to the recording medium 2. To settle.
A foam-like fixing liquid layer is formed on the application roller 17, and resin fine particles (toner particles) that form an image on the recording medium 2 are not offset on the application roller 17. Even if the foam-like fixing solution is thickly applied to the resin fine particle layer or the recording medium, the bulk density of the foam-like fixing solution is extremely low. By foaming, a small amount of the liquid containing the softening agent can be applied to the resin fine particle layer.
Note that an application belt may be used instead of the application roller 17.

[Fixing of color image]
When the image to be formed is color, as shown in FIG. 6, the thickness of the unfixed toner layer on the recording medium 2 such as paper is two-color overlapping toner layer 22, multi-color compared to the single-color toner layer 21. The thickness of the superposed toner layer 23 increases in thickness, and the thickness of the shadow-based multicolor toner layer is approximately twice the thickness of the monochromatic toner layer 21. Therefore, when the film thickness of the foam-like fixing solution on the coating roller 17 is adjusted to an amount necessary to wet all the toner particles of the single-color toner layer 21 with the fixing solution, in the portion of the multi-color overlapping toner layer 23, Only about half of the toner particles in the toner layer can be wetted, and the portion of the multi-color superposed toner layer 23 is poorly fixed.
Conversely, when the fixing liquid is applied by adjusting the film thickness of the foam-like fixing liquid on the application roller 17 to such an extent that all the toner particles of the multicolor overlapping toner layer 23 are wetted, the toner particles of the single-color toner layer 21 are There is a problem that the toner layer is excessively wetted, the resin in the toner is too soft, and the toner layer is tacky.

As a result of intensive studies to solve this problem, the present inventors have a great effect by controlling the film thickness of the foam-like fixing liquid on the application roller 17 according to the thickness of the toner layer. I understood. FIG. 7 shows a specific example of the thickness control of the foam-like fixing liquid on the application roller 17. FIG. 7A shows an example of a toner image on the recording medium 2. As shown in FIG. 7B, the recording medium includes areas 21a to 21c of a single color toner layer as shown in a sentence, areas 23a and 23b of a full color photograph made up of a multicolor overlapping toner layer, and an area 23c such as a multicolor graph. With respect to the direction perpendicular to the conveyance direction 2, the area 24 for the single color portion reduces the application amount of the fixing liquid, and the area 25 for the color image portion increases the application amount of the fixing liquid. By doing so, the toner of the multi-colored part is fixed satisfactorily, and the tactile sensation does not occur in the single-colored part.
Note that when the liquid fixer is dropped on the surface of the coating roller 17, it tends to spread in the surface from the dripping portion. However, the foam-like fixer has different surface tension and fluidity unlike a normal liquid. When the foam-like fixing liquid is partially adhered on the surface of the application roller 17, the adhesion width is maintained and it is very difficult to spread in the plane. As in the present invention, the fixing to the application roller 17 is performed for each divided block. It has a great feature that changing the film thickness of the liquid is much easier than in the case of a liquid fixing liquid.

Further, as shown in FIG. 8A, by controlling the film thickness of the foam-like fixer on the application roller 17 in a direction perpendicular to the conveyance direction of the recording medium 2 and for each fine block, Since the amount of fixing liquid applied can be finely controlled for each of the single color toner area 26, the toner-free area 27, the first multicolor overlaid toner area 28, or the second multicolor overlaid toner area 29 on the recording medium 2. The consumption of the fixing solution can be reduced, and the optimum application amount of the fixing solution can be controlled in accordance with the thickness of the toner layer.
Further, as shown in FIG. 8B, the ON / OFF control of the fixing liquid supply port 13 and the gap control of the film thickness control blade 16 are also applied to the regions 31 to 35 in the direction parallel to the conveyance direction of the recording medium 2. By performing the above, the thickness of the foam-like fixing liquid on the application roller 17 can be controlled more finely according to the thickness of the toner layer.
Note that it is difficult to control the direction parallel to the conveyance direction of the recording medium 2 as the conveyance speed increases, but the surface tension and fluidity of the foam-like fixing liquid are suppressed as compared with the liquid fixing liquid. Therefore, the control response of the fixing liquid is excellent, and it is possible to follow the control sufficiently even if the conveyance speed is high.

Next, a configuration for controlling the application amount of the foam-like fixing liquid according to the thickness of the resin fine particle layer (toner layer) containing the coloring material on the recording medium with respect to the conveyance direction of the recording medium will be specifically described. To do.
[Example 1]
In the fixing device according to the first embodiment of the present invention (corresponding to claims 1 and 2), as shown in FIG. 9, the supply port 13 from the foam-like fixing liquid generating means 11 to the application roller 17 has a longitudinal direction. A film-thickness control blade that controls the film pressure of the foam-like fixer is configured as a split-type control blade 16a. A gap is provided between each blade of the split type control blade 16a and the application roller 17, and each blade is connected to an actuator (not shown). The gaps between the application roller 17 and the individual blades of the split type control blade 16a can be changed by moving individually.
When changing the application amount of the foam-like fixing liquid in a direction perpendicular to or parallel to the conveyance direction of the recording medium (see FIGS. 7B and 8), in an area where the application amount is to be increased, The gap between the split type control blade 16a and the application roller 17 is widened to increase the film thickness of the foam-like fixing liquid layer on the application roller 17, and the gap is narrowed in the region where the application amount is desired to be reduced. By reducing the thickness of the upper foam-like fixing liquid layer, it is possible to apply the toner in accordance with the thickness of the toner layer on the recording medium.

As an actuator for individually driving the individual blades of the split control blade 16a, a micromotor using a ball screw, a piezoelectric element, a solenoid, or the like can be used. The variable amount of the gap between the split type control blade 16a and the application roller 17 needs to be determined by the bulk density of the foam-like fixing liquid, but generally the bulk density is 0.03 g / cm ^{3 to} 0.1 g / cm ³ . In the range, 30 μm to 80 μm is desirable, and the gap is controlled with 30 μm in the halftone image area, 50 μm in the monochromatic image area, and 80 μm in the multicolor image area as a guide.
The finer the division width of the divided control blade 16a, the finer the application amount of the fixing liquid can be controlled. However, there is a risk that the manufacturing cost of the fixing device may be increased, and the image to spread zones such as small and medium-sized offices. When the fixing device of the present invention is incorporated in the forming apparatus, the number of divisions is preferably 4 to 6 with respect to the A4 plate length in order to reduce costs. The gap control between the split type control blade 16a and the application roller 17 is set according to an image signal input to the image forming apparatus.

[Example 2]
As shown in FIG. 10, the fixing device according to the second embodiment of the present invention (corresponding to claims 3 and 4) is integrated with the film thickness control blade 16, and the foam-like fixing liquid is applied to the application roller 17. The supply means 12 includes an individual supply port 13a composed of a plurality of supply ports. The individual supply port 13a is configured to be able to individually turn on / off the supply of foam-like fixing liquid by a valve (not shown). In a direction perpendicular to or parallel to the conveyance direction of the recording medium (see FIGS. 7B and 8), the foam from the individual supply port 13a is formed according to the thickness of the toner layer on the recording medium. ON / OFF control of the supply of the state fixer.
Since the fixing solution used in the present invention is formed into a foam, it exhibits a behavior different from that of a normal fluid. That is, since the foam in the foam is strongly bonded, the fluidity is extremely suppressed, and even if the foam-like fixing liquid is dropped on the application roller 17, it is difficult to diffuse in the longitudinal direction of the application roller 17, and the film thickness control blade Even if 16 is integrated, a foam-like fixing liquid layer is formed on the application roller 17 only in the vicinity of the dropped region. This is a behavior that cannot occur with a normal liquid fixing solution.

When the fixing device according to the second embodiment is incorporated in an image forming apparatus and only one sheet is printed using the image forming apparatus, the foam-like fixing liquid remains on the application roller 17 when the sheet is not used for a long time. The residual fixing solution gradually breaks up bubbles and loses the optimum form state, and there is a possibility that fixing failure may occur when printing is performed again with the image forming apparatus.
Therefore, when the supply amount of the foam-like fixing liquid is controlled, it is desirable to supply the amount of the foam-like fixing liquid necessary for printing one sheet by the image forming apparatus every time one sheet is printed on the application roller 17. By doing so, residual fixing liquid on the application roller 17 is suppressed at the end of printing. An electromagnetic valve or the like can be applied as a valve for turning ON / OFF the foam-like fixing liquid supplied from the individual supply port 13a.

Example 3
As shown in FIG. 11, the fixing device according to the third embodiment of the present invention (corresponding to claim 5) is provided on the outer peripheral surface of the application roller 17 in the fixing device according to the second embodiment (see FIG. 10). In this configuration, a partition plate 19 is provided.
In the fixing device of the second embodiment, the foam-like fixing liquid layer is formed only on the application roller 17 in the vicinity of the individual supply port 13a. However, a large number of sheets are printed by the image forming apparatus incorporating the fixing device. When continuously performed, the foam-like fixing liquid layer formed at one supply port may gradually spread in the longitudinal direction of the application roller 17. In order to prevent this, a partition plate 19 is provided on the outer peripheral surface of the application roller 17 along the pitch of each supply port of the individual supply port 13a. Since the foam-like fixing liquid has extremely low fluidity, the partition plate 19 does not necessarily need to be in close contact with the application roller 17 and may have a gap.

Example 4
As shown in FIG. 12, the fixing device according to the fourth embodiment of the present invention (corresponding to claim 6) is integrated with the film thickness control in the fixing device according to the second embodiment (see FIG. 10). The blade 16 is a split type control blade 16a as in the fixing device of the first embodiment (see FIG. 9).
By doing so, it is possible to combine ON / OFF control of the individual supply port 13a and gap control of the split type control blade 16a, so that a finer film of the foam-like fixing liquid layer on the coating roller 17 can be obtained. Thickness control is possible. Furthermore, even if the conveyance speed of the recording medium is increased, since the application amount control of the foam-like fixing liquid is performed twice, the responsiveness is improved and the increase in speed can be followed.

Example 5
As shown in FIG. 13, the fixing device according to the fifth embodiment of the present invention has a configuration in which a partition plate 19 is further provided in the fixing device according to the fourth embodiment (see FIG. 12). By providing the partition plate 19, diffusion of the foam-like fixing solution in the longitudinal direction on the coating roller 17 is suppressed, and the film thickness of the foam-like fixing solution layer can be more precisely controlled.

Example 6
As shown in FIGS. 14 and 15, the fixing device according to the sixth embodiment of the present invention uses a means for injecting a fixing liquid sealed in a high-pressure sealed container as a means for forming a fixing liquid.
In Examples 1 to 5 described above, the fixing solution foaming means is a means such as agitation. However, as shown in FIGS. 14 and 15, the fixing device of Example 6 uses the fixing solution together with the liquefied gas. A means (nozzle or the like) 37 that is sealed in a high-pressure sealed container 36 and formed into a foam by injection is used. This is done by using a plurality of high-pressure sealed containers 36, 36... According to the thickness of the toner layer on the recording medium with respect to the conveyance direction of the recording medium. , 38... Can be individually controlled to control the applied amount.
In the first to fifth embodiments, the surface of the film thickness control blade 16 is disposed with a gap on the coating roller 17. However, as shown in FIG. 14, the film thickness control blade 16 is disposed on the surface of the coating roller 17. You may arrange in counter form. Also in this case, a gap is provided between the tip of the film thickness control blade 16 and the surface of the application roller 17.

  In all of the above embodiments, the application roller 17 is provided as the contact imparting means. However, as shown in FIG. 15, a belt-shaped member application belt 39 may be provided instead of the application roller. As the coating belt 39, for example, a member such as a seamless nickel belt or a seamless PET (polyethylene terephthalate) film coated with a releasable fluororesin such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) Can be used.

[Prescription of fixer]
Next, the prescription of the fixing solution will be described. As described above, the foam-like fixing liquid has a structure in which bubbles are contained in a liquid containing a softening agent. The liquid containing the softening agent stably contains bubbles, but it is desirable to have a foaming agent and a foam-increasing agent in order to form a foam layer comprising bubbles of uniform size as much as possible. In addition, when the viscosity is high to some extent, it is desirable to contain a thickener since the bubbles are stably dispersed in the liquid.
As the foaming agent, a fatty acid salt is desirable. Since the fatty acid salt has surface activity, it lowers the surface tension of the fixing solution containing water, makes the fixing solution easy to foam, and the fatty acid salt has a layered lamellar structure on the foam surface, so that the foam wall (plateau boundary) is 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. As the fatty acid, a saturated fatty acid resistant to oxidation is desirable from the viewpoint of long-term stability in the air. However, the inclusion of a slight amount of unsaturated fatty acid salt in the fixing solution containing saturated fatty acid salt helps to dissolve and disperse the fatty acid salt in water, and excellent foaming at a low temperature of 5 ° C to 15 ° C. Therefore, fixing can be stabilized in a wide environmental temperature range. Further, even when the fixing solution is left for a long period of time, separation of the fatty acid salt in the fixing solution can be prevented.

As the fatty acid used in the saturated fatty acid salt, saturated fatty acids having 12, 14, 16, and 18 carbon atoms, specifically lauric acid, myristic acid, palmitic acid, and stearic acid are suitable. Since a saturated fatty acid salt having 11 or less carbon atoms has a strong odor, an image forming apparatus using the fixing solution is not suitable for use in an office or home. In addition, saturated fatty acid salts having 19 or more carbon atoms are less soluble in water and significantly lower the stability of the fixing solution. Saturated fatty acid salts with these saturated fatty acids are used alone or in combination as a foaming agent.
In order to prevent the offset, it is desirable that the thickness of the foam-like fixing liquid layer at the application portion is larger than the thickness of the resin fine particle layer. Further, in order to make the bubbles easily adhere to the resin fine particles, it is desirable that the bubbles be larger than the resin fine particles. When the resin fine particles are toner particles, the toner particles in the dry electrophotographic method have a size of about 4 to 10 μm, and the unfixed toner layer on the paper medium is about 10 to 30 μm, and therefore contains a softening agent. The size of the bubbles contained in the liquid is preferably about 5 to 30 μm.

  In addition, in a configuration in which the fixing solution is stored in a high-pressure sealed container, a configuration in which a gas that becomes a gas under atmospheric pressure or an atmospheric component gas is dissolved or dispersed in a liquid containing a softening agent is desirable. As the gas that becomes a gas under atmospheric pressure, aliphatic hydrocarbons such as propane, butane, pentane, hexane, and dimethyl ether are suitable. Nitrogen gas, argon gas, etc. are suitable as the atmospheric component gas. In this configuration, since the high-pressure gas is used, the means for supplying the fixing solution in the form of foam to the coating member can be simplified or not required. Further, since the means for mechanically applying a shearing force to the fixing solution and the means for supplying the fixing solution in the form of a foam to the coating member can be simplified, the fixing device can be easily downsized.

The softening agent that is softened by dissolving or swelling the resin 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 softening agent has an acute oral toxicity LD50 of more than 3 g / kg, more preferably 5 g / kg, from the viewpoint of safety to the human body. As aliphatic esters are frequently used as cosmetic raw materials, they are highly safe for the human body.
Further, the toner is fixed to the recording medium in a device that is frequently used in a sealed environment, and the softener remains in the toner even after the toner is fixed to the recording medium. Is preferably free from the generation of volatile organic compounds (VOC) and unpleasant odors. That is, the softener preferably does not contain volatile organic compounds (VOC) and substances that cause unpleasant odors. Aliphatic esters have a high boiling point and low volatility and have no irritating odor as compared to generally used organic solvents (toluene, xylene, methyl ethyl ketone, ethyl acetate, etc.).

  In addition, as a practical odor measurement scale that can measure odors in office environments with high accuracy, the odor index (10 × log) by the three-point comparison odor bag method that is sensory measurement The dilution factor of the substance until it disappears)) can be used as an indicator of odor. The odor index of the aliphatic ester contained in the softener is preferably 10 or less. In this case, an unpleasant odor is not felt in a normal office environment. Furthermore, it is preferable that not only the softening agent but also other liquid agents contained in the fixing solution have no unpleasant odor and irritating odor.

In the fixing solution of the present invention, preferably, the aliphatic ester includes a saturated aliphatic ester. When the above aliphatic ester contains a saturated aliphatic ester, the storage stability (resistance to oxidation, hydrolysis, etc.) of the softener can be improved. Further, saturated aliphatic esters are highly safe for the human body, and 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 formed 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, in the fixing solution of the present invention, preferably, the general formula of the saturated aliphatic ester is
R1COOR2
Wherein R1 is an alkyl group having 11 to 14 carbon atoms, and R2 is a linear or branched alkyl group having 1 to 6 carbon atoms.
The saturated aliphatic ester includes a compound represented by the general formula R1COOR2, wherein R1 is an alkyl group having 11 to 14 carbon atoms, and R2 is a linear type having 1 to 6 carbon atoms or When it is a branched alkyl group, the solubility or swelling property with respect to the resin contained in the toner can be improved. Moreover, said compound has an odor index of 10 or less, and has no unpleasant odor or irritating odor.

  Examples of the aliphatic monocarboxylic acid ester that is the above compound include ethyl laurate, hexyl laurate, ethyl tridecylate, isopropyl tridecylate, ethyl myristate, isopropyl myristate, and the like. Many of these aliphatic monocarboxylic acid esters, which are the above compounds, are soluble in oily solvents, but not in water. Therefore, for many of the aliphatic monocarboxylic acid esters which are the above-mentioned compounds, in an aqueous solvent, glycols are contained in the fixing solution as a solubilizing agent and are in the form of a solution or a microemulsion.

In the fixing solution of the present invention, preferably, the aliphatic ester includes an aliphatic dicarboxylic acid ester. When the aliphatic ester includes 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 until the fixing liquid is applied to the unfixed toner on the recording medium and the toner is fixed on the recording medium is within 1 second. When the aliphatic ester includes an aliphatic dicarboxylic acid ester, the 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. It is possible to be 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, in the fixing solution of the present invention, preferably, the general formula of the aliphatic dicarboxylic acid ester is
R3 (COOR4) 2
R3 is an alkylene group having 3 to 8 carbon atoms, and R4 is a linear or branched alkyl group having 3 to 5 carbon atoms.
The aliphatic dicarboxylic acid ester includes a compound represented by the general formula R3 (COOR4) 2, wherein R3 is an alkylene group having 3 to 8 carbon atoms, and R4 has 3 to 5 carbon atoms. In the case of the linear or branched alkyl group, the solubility or swelling property with respect to the resin contained in the toner can be improved. Moreover, said compound has an odor index of 10 or less, and has no unpleasant odor or irritating odor.

  Examples of the aliphatic dicarboxylic acid ester that is the above compound include diethylhexyl succinate, dibutyl adipate, diisobutyl adipate, diisopropyl adipate, diisodecyl adipate, diethyl sebacate, and dibutyl sebacate. Many of these aliphatic dicarboxylic acid esters, which are the above compounds, are soluble in oily solvents, but not in water. Therefore, in an aqueous solvent, 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 of the present invention, preferably, the aliphatic ester includes an aliphatic dicarboxylate dialkoxyalkyl. When the above aliphatic ester contains an aliphatic dicarboxylic acid dialkoxyalkyl, the fixing property of the toner to the recording medium can be improved.
In the fixing solution of the present invention, preferably, the general formula of the above aliphatic dicarboxylic acid dialkoxyalkyl is:
R5 (COOR6-O-R7) 2
R5 is an alkylene group having 2 to 8 carbon atoms, R6 is an alkylene group having 2 to 4 carbon atoms, and R7 is 1 to 4 carbon atoms. It is an alkyl group.
The aliphatic dicarboxylic acid dialkoxyalkyl includes a compound represented by the general formula R5 (COOR6-O-R7) 2, wherein R5 is an alkylene group having 2 to 8 carbon atoms, and R6 is carbon. When R7 is an alkylene group having 2 or more and 4 or less and R7 is an alkyl group having 1 or more and 4 or less carbon atoms, it is possible to improve the solubility or swelling property with respect to the resin contained in the toner. Moreover, said compound has an odor index of 10 or less, and has no unpleasant odor or irritating odor.

Examples of the aliphatic dicarboxylate dialkoxyalkyl which is the above compound include diethoxyethyl succinate, dibutoxyethyl succinate, diethoxyethyl adipate, dibutoxyethyl adipate, diethoxyethyl sebacate and the like. . In these aliphatic dicarboxylic acid dialkoxyalkyl aqueous solvents, glycols are contained in the fixing solution as a dissolution aid and are dissolved or in the form of a microemulsion.
The fine particles containing the resin to be fixed are not limited to toner, and any fine particles containing a colorant and a resin may be used.

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 present invention. The toner includes a color material, 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. Examples of suitable binder resins include polystyrene resins, styrene-acrylic copolymer resins, polyester resins, and the like, and examples of the release agent include carbanau wax and polyethylene. And wax components. 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. 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 oily property in the present invention means a property that the solubility in water at room temperature (20 ° C.) is 0.1% by weight or less.

  The fixing solution in the form of foam preferably 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 fixing solution in the form of foam 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 surfaces of hydrophobic silica and hydrophobic titanium oxide, and is approximately 20 mN / m. Has a surface energy of a degree. In reality, the entire surface of the water-repellent treated toner is not completely covered with hydrophobic fine particles, so the surface energy of the water-repellent treated toner is estimated to be approximately 20 to 30 mN / m. Is done. Therefore, in order to have an affinity for the water-repellent toner (having sufficient wettability), it is preferable that the surface tension of the foamed fixing liquid is 20 to 30 mN / m.

  In the case of using an aqueous solvent, it is preferable that the surface tension is 20 to 30 mN / m by adding a surfactant. 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 the 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 prices or polyhydric alcohols, it is effective in preventing curling of recording media such as paper.

In addition, in order to improve the permeability in the fixing solution and prevent curling of a recording medium such as paper, a configuration in which an O / W emulsion or a W / O emulsion is formed containing an oil component is also desirable. In that case, as specific dispersants, sorbitan fatty acid esters such as sorbitan monooleate, sorbitan monosterate and sorbitan sesquioleate, and sucrose esters such as sucrose laurate and sucrose stearate are desirable. .
In addition, as a method for dissolving the softening agent or fixing the microemulsion during fixing, for example, a mechanical stirring means such as a homomixer or a homogenizer using a rotary blade, and vibration such as an ultrasonic homogenizer are 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.

  In addition, the toner fixing device adds the dissolved or swollen toner with a component (softener) that dissolves or swells at least a part of the resin contained in the toner after supplying the fixing solution of the present invention to the toner. In order to press, you may have a pair of smoothing roller (hard roller). By applying pressure to the dissolved or swollen toner by the pair of smoothing rollers, the surface of the dissolved or swollen toner layer can be smoothed to give gloss to the toner. Furthermore, by fixing the dissolved or swollen toner into the recording medium, the fixability of the toner to the recording medium can be improved.

  In an image forming apparatus according to another embodiment of the present invention, if an image of a toner containing a resin is formed on a recording medium using the above-described image forming method according to the present invention, the image forming apparatus according to this another invention can be obtained. Also in the image forming apparatus according to the embodiment, as described above, it is possible to provide an image forming method and an image forming apparatus capable of fixing toner onto a recording medium more efficiently.

[Specific method of film thickness control]
Next, a specific method for controlling the film thickness of the foam-like fixing liquid on the application roller will be described with reference to FIG. FIG. 16 shows a specific operation flow.
Based on the scanner image data of the image forming apparatus and the input image data from the PC (steps S1 and S2), using an image processor in the image forming apparatus, yellow (Y), magenta (M), cyan (C), The information is decomposed into black (BK) color information and developed into binary data (step S3). Based on the binary data, the necessary toner layer thickness on the recording medium for each color is calculated (step S3). Based on the calculated data, the thickness of the toner layer in each divided block is calculated (step S4), and the toner thickness and the amount of fixing liquid applied necessary for fixing are calculated based on the conversion table (step S5).

  When controlling the foam-like fixer from the supply port based on the calculation data from the conversion table, the supply amount control value is calculated from the supply amount (applied amount) and the fixer film thickness conversion table on the application roller. (Step S6). In addition, when controlling the film thickness of the foam-like fixing liquid on the coating roller with the film thickness control blade, the film thickness is determined based on the gap between the film thickness control blade and the coating roller and the fixing liquid film thickness conversion table on the coating roller. A gap control value between the control blade and the application roller is calculated (step S7). Based on these calculated values, a signal is sent to the supply port ON / OFF drive circuit or the blade drive control circuit to turn on / off the supply port and drive the film thickness control blade (steps S8 and S9). By such an operation flow, the thickness of the foam-like fixing liquid on the coating roller is controlled according to the thickness of the toner layer on the recording medium.

[Image forming apparatus]
Next, an image forming apparatus to which the fixing device of the present invention is applied will be described with reference to FIG. FIG. 17A is a schematic diagram of the entire color electrophotographic tandem image forming apparatus, and FIG. 17B is a schematic diagram of one image forming unit of the image forming apparatus.
The image forming apparatus is, for example, a copying machine, a printer, or the like, and has an intermediate transfer belt 41 as a toner image carrier as shown in FIG. The intermediate transfer belt 41 is stretched around three support rollers 42 to 44 and rotates in the direction of arrow C in the drawing. On the intermediate transfer belt 41, black (BK), yellow (Y), magenta (M), and cyan (C) image forming units 45 to 48 are arranged. Above these image forming units, an exposure device (not shown) is arranged. For example, when the image forming apparatus is a copying machine, each exposure L1 to L4 for reading image information of an original with a scanner and writing an electrostatic latent image on each photosensitive drum according to the image information is performed. Irradiated by an exposure apparatus. A secondary transfer device 49 is provided at a position facing the support roller 44 of the intermediate transfer belt 41 with the intermediate transfer belt 41 interposed therebetween. The secondary transfer device 49 is composed of a secondary transfer belt 52 stretched between two support rollers 50 and 51. As the secondary transfer device 49, a transfer roller may be used in addition to the transfer belt. Further, a belt cleaning device 53 is disposed at a position facing the support roller 42 of the intermediate transfer belt 41 with the intermediate transfer belt 41 interposed therebetween. The belt cleaning device 53 is arranged to remove the toner remaining on the intermediate transfer belt 41.

The recording paper 54 as a recording medium is guided to the secondary transfer unit by a pair of paper feed rollers 55, and the secondary transfer belt 52 is pressed against the intermediate transfer belt 41 when the toner image is transferred to the recording paper 54. Thus, the toner image is transferred. The recording paper 54 to which the toner image has been transferred is conveyed by the secondary transfer belt 52, and the unfixed toner image transferred to the recording paper 54 is formed in a form based on image information from an exposure device (not shown). Fixing is performed by the toner fixing device of the present invention that controls the film thickness of the fixing solution.
That is, the unfixed toner image transferred to the recording paper 54 is a book that controls the film thickness of the foam-like fixing liquid layer based on image information (for example, color image or black solid image information) from the exposure device. A foam-like fixing solution is applied from the fixing device of the invention. This foam-like fixing liquid contains a part (softener) that dissolves or swells at least a part of the resin contained in the toner, and records the unfixed toner image transferred onto the recording paper 54. Fix on paper.

[Image forming unit]
Next, an image forming unit of the image forming apparatus will be described with reference to FIG.
In the image forming units 45 to 48, a charging device 57, an exposure device (not shown), a developing device 58, a cleaning device 59, and a charge eliminating device 60 are disposed around the photosensitive drum 56. A primary transfer device 61 is provided at a position facing the photosensitive drum 56 with the intermediate transfer belt 41 interposed therebetween.
The charging device 57 is a contact charging type charging device employing a charging roller. The charging device 57 uniformly charges the surface of the photosensitive drum 56 by bringing a charging roller into contact with the photosensitive drum 56 and applying a voltage to the photosensitive drum 56. As the charging device 57, a non-contact charging type charging device using a non-contact scorotron or the like may be employed.
The exposure apparatus (not shown) irradiates exposure L for writing an electrostatic latent image on the photosensitive drum in accordance with image information.

Further, the developing device 58 causes the toner in the developer to adhere to the electrostatic latent image on the photosensitive drum 56 to visualize the electrostatic latent image. Here, the toners corresponding to the respective colors are made of resin materials colored in the respective colors, and these resin materials are dissolved or swollen by the fixing solution in the present invention. The developing device 58 includes a stirring unit and a developing unit (not shown), and the developer that has not been used for development is returned to the stirring unit and reused. The toner concentration in the agitation unit is detected by a toner concentration sensor, and is controlled so that the toner concentration is constant.
Further, the primary transfer device 61 transfers the toner visualized on the photosensitive drum 56 to the intermediate transfer belt 41. Here, a transfer roller is employed as the primary transfer device 61, and the transfer roller is pressed against the photosensitive drum 56 with the intermediate transfer belt 41 interposed therebetween. As the primary transfer device 61, a conductive brush, a non-contact corona charger, or the like can be employed.

The cleaning device 59 removes unnecessary toner on the photosensitive drum 56. As the cleaning device 59, a blade having a tip pressed against the photosensitive drum 56 can be used. Here, the toner collected by the cleaning device 59 is collected and reused in the developing device 58 by a collecting screw and a toner recycling device (not shown).
Further, the static eliminator 60 is constituted by a lamp, and irradiates light to initialize the surface potential of the photosensitive drum 56.
In the present invention, “less tackiness” means that the tensile force of the fixing surface of the colorant-containing resin fine particle layer at a weight of 10 g is measured using a commercially available tack meter, and the tensile force is about 0.01 N or less. Means that.
Further, in the present invention, “good fixability” means that the fixing surface of the colorant-containing resin fine particle layer is rubbed with a white cloth at a constant load for a certain number of times, and the stain on the waste surface has an optical density of 0.3 or less. Means.

〔Concrete example〕
Next, specific examples of the fixing solution and fixing in the present invention will be described.
[Prescription of fixer]
<Liquid containing softener>
Diluent: ion exchange water 65wt%
Softening agent: Diethoxyethyl succinate (Croda Croda DES) 10wt%
Thickener: Propylene glycol 10wt%
Foam enhancer: palm fatty acid diethanolamide (comicado DEA) 2wt%
Foaming agent: potassium palmitate 5 wt%
Potassium myristate 3wt%
Potassium stearate 2wt%
Dispersant: POE (20) lauryl sorbitan 2 wt%
(Kao Leodoll TW-S120V)
Polyethylene glycol monostearate 1wt%
(Kao Emanon 3199)
The dispersant was used to promote the solubility of the softener in the diluent solvent.
First, at the above component ratio, a softening agent was removed at a liquid temperature of 90 ° C. and mixed and stirred to prepare a solution. Next, a softening agent was mixed to prepare a fixing solution (stock solution before forming) in which the softening agent was dissolved.

[Fixing solution forming method]
A large bubble generating means and a means for generating fine bubbles based on the bubbles were combined.
<Large bubble generation means>
It was set as the structure which a liquid passes a microporous sheet, entraining air.
Liquid fixer storage container: Bottle made of PET resin Liquid supply pump: Tube pump (Tube inner diameter 2 mm, Tube material: Silicone rubber)
Supply flow path: Silicone rubber tube with an inner diameter of 2 mm Microporous sheet for making large bubbles: # 400 stainless steel mesh sheet (opening approx. 40 μm)
<Means for generating fine bubbles from large bubbles>
A large bubble is conveyed in the double cylinder which the inner cylinder rotates, and the inner cylinder of the double cylinder is fixed to the rotation shaft and is rotated by a rotation drive motor. The material of this double cylinder was PET resin, the inner diameter of the outer cylinder was 10 mm, the length was 120 mm, the cylindrical outer shape of the inner circle was 8 mm, and the length was 100 mm.
The number of rotations was variable in the range of 1000 to 2000 rpm.

[Coating equipment]
Based on the configuration of the fixing device of Example 5 shown in FIG.
The foam-like fixing solution generating means 11 to the individual supply port 13a were supplied by a single tube pump using a polypropylene tube, and an electromagnetic valve was provided at the individual supply port 13a. The application roller 17 was an aluminum roller having a diameter of 30 mm and a length of 240 mm coated with a fluorine resin.
The divided control blade 16a is made of glass having a thickness of 1 mm, a length of 20 mm, and a height of 20 mm, and is bonded to an aluminum support connected to an actuator by a micromotor, with a gap of 0.1 mm in the longitudinal direction of the coating roller 17. Eleven were arranged. The gap between the coating roller 17 and the glass divided control blade 16a can be individually controlled in the range of 30 μm to 100 μm.
Further, partition plates 19 made of PET film having a thickness of 0.1 mm were arranged for each supply port at intervals of 20 mm.

[Result]
IpsioColor CX8800 (manufactured by Ricoh) is used as the printer, and the color image of the unfixed toner is PPC using the test chart image data that is 30 mm on both sides with respect to the longitudinal direction of the paper, the left half monochrome document, and the right half full color photographic image. Formed on paper (Ricoh T-6200 A4 size). The paper on which the unfixed toner image is formed is conveyed to the fixing device, and the supply port is opened and closed and divided according to the thickness of the toner layer of the margin portion, monochrome document portion, and full color portion based on the image data in advance. Fixing was performed with the control blade gap controlled. For comparison, fixing without control according to the present invention was also performed. The results are shown in Table 1.


As shown in Table 1, good fixing can be achieved by changing the thickness of the foam-like fixing liquid layer on the coating roller in accordance with the thickness of the toner layer based on the image data along the paper conveyance direction. It has become possible.

FIG. 4 is an explanatory diagram relating to the principle of the present invention, (a) is a schematic diagram of a fixing solution contact imparting means when a liquid fixing solution is used in a typical application roller fixing device, and (b) is a schematic diagram of (b). It is a conceptual diagram showing the force acting on the toner layer at the contact surface between the coating roller and the recording medium in (a). These are explanatory drawings similar to FIG. 1 (b), and are conceptual diagrams when a foam-like fixing liquid is used. These are the schematic diagrams which show the example of a layer structure when apply | coating foam-form fixing solution. FIG. 4 is a schematic explanatory diagram when a foam-like fixing solution is applied onto an unfixed toner layer of a recording medium. FIG. 4A shows a case where the foam is broken, and FIG. Show the case. FIG. 3 is a schematic view of a fixing device that applies a foam-like fixing liquid onto a recording medium with a coating roller. FIG. 5 is a schematic diagram for explaining fixing of color images having different thicknesses of unfixed toner layers. FIG. 4 is an explanatory diagram regarding thickness control of a foam-like fixing liquid layer on a coating roller, (a) is a specific example of a toner image on a recording medium, and (b) is a direction perpendicular to the conveyance direction of the recording medium. The case where the application amount of the foam-like fixing liquid is controlled will be described. Is an explanatory diagram regarding the film thickness control block of the foam-like fixing liquid on the application roller, and (a) is a case where the film thickness control is performed in a fine block with respect to the direction perpendicular to the conveyance direction of the recording medium. (b) is a case where film thickness control is performed in a direction parallel to the conveyance direction of the recording medium. FIG. 3 is a schematic perspective view for explaining a main part of the fixing device according to the first embodiment of the present invention. These are the typical perspective views explaining the principal part of the fixing device by Example 2 of this invention. These are the typical perspective views explaining the principal part of the fixing device by Example 3 of this invention. These are the typical perspective views explaining the principal part of the fixing device by Example 4 of this invention. These are the typical perspective views explaining the principal part of the fixing device by Example 5 of this invention. These are the typical explanatory drawings of the fixing device by Example 6 of this invention, and show what used the application roller as a contact provision means. These are the typical explanatory drawings of the fixing device by Example 6 of this invention, and show what used the application belt as a contact provision means. These are the operation | movement flowcharts which control the film thickness of the foam-form fixing liquid layer on an application | coating roller. FIG. 1 is a schematic diagram of an image forming apparatus, (a) is a schematic diagram of an entire color tandem image forming apparatus, and (b) is a schematic diagram of one image forming unit in the image forming apparatus.

Explanation of symbols

2 ... Recording medium (paper, cloth, etc.) 3 ... Toner layer (resin fine particle layer)
DESCRIPTION OF SYMBOLS 5 ... Fixing liquid 5f ... Foam-shaped fixing liquid 7 ... Application | coating roller 11 ... Foam-shaped fixing liquid generation means 12 ... Supply means 13 ... Fixing liquid supply port 13a ... Individual supply port 15 ... Stirring roller 16 ... Film thickness control blade 16a ... Division Shape control blade 17 ... coating roller 18 ... pressure roller 19 ... partition plate 20 ... contact imparting means 36 ... high pressure sealed container 37 ... foaming means (nozzle etc.)
38 ... Actuator 45-48 ... Image forming unit 49 ... Secondary transfer device 61 ... Primary transfer device

Claims (13)

The resin fine particle layer containing the color material formed on the recording medium is fixed on the recording medium with a fixing solution containing a softening agent that softens the resin fine particles by dissolving or swelling at least part of the resin. A fixing device,
A foam-like fixing solution generating means for forming the fixing solution into a foam;
Contact applying means for applying the foam-like fixing liquid to the resin fine particle layer on the recording medium;
A foam-like fixing liquid supply means for supplying the foam-like fixing liquid to the contact applying means;
A thickness control means for controlling the thickness of the foam-like fixing liquid layer on the contact applying means,
A fixing device that controls the thickness of the foam-like fixing liquid layer on the contact applying means according to the thickness of the resin fine particle layer on the recording medium.   The thickness control means is divided into a plurality of parts in the longitudinal direction of the contact applying means, and is arranged on the contact applying means for each divided thickness control means according to the thickness of the resin fine particle layer on the recording medium. The fixing device according to claim 1, wherein the thickness of the foam-like fixing liquid layer is controlled.   The thickness of the foam-like fixing liquid layer on the contact applying means by the thickness control means is controlled by controlling the supply amount from the foam-like fixing liquid supply means according to the thickness of the resin fine particle layer on the recording medium. The fixing device according to claim 2.   A plurality of the foam-like fixing liquid supply means are arranged in a direction perpendicular to the conveying direction of the recording medium, and the thickness of the foam-like fixing liquid layer on the contact applying means is controlled by resin fine particles on the recording medium. The fixing device according to claim 3, wherein the fixing is performed by individually turning on and off each of the foam-like fixing liquid supply means according to the thickness of the layer.   The said contact provision means is divided | segmented for every block by the partition plate in a longitudinal direction, and the supply amount of foam-form fixing liquid is controlled for every block, The claim 2 characterized by the above-mentioned. Fixing device.   The thickness control means is divided into a plurality of parts in the longitudinal direction of the contact applying means, and is individually controlled according to the width of the recording medium or the image width of the resin fine particle layer on the recording medium. 6. The fixing device according to claim 2, wherein the thickness of the foam-like fixing liquid layer on the contact applying means is changed.   The thickness of the foam-like fixing liquid layer on the contact applying means is controlled in accordance with the maximum thickness of the resin fine particle layer for each of the blocks divided into a plurality in the longitudinal direction of the contact applying means. The fixing device according to claim 2.   The fixing solution for use in the fixing device according to claim 1, comprising water, a fatty acid salt, and a softening agent.   The fixing solution according to claim 8, wherein the fatty acid salt is a sodium salt, a potassium salt, or an amine salt. The softener includes a compound represented by the general formula R1COOR2,
R1 is an alkyl group having 11 to 14 carbon atoms,
The fixing solution according to claim 8 or 9, wherein R2 is an alkyl group having 1 to 6 carbon atoms. The softener includes a compound represented by the general formula R3 (COOR4) 2,
R3 is an alkylene group having 3 to 8 carbon atoms,
10. The fixing solution according to claim 8, wherein R4 is an alkyl group having 3 to 5 carbon atoms. The softening agent includes a compound represented by the general formula R5 (COOR6-O-R7) 2,
R5 is an alkylene group having 2 to 8 carbon atoms,
R6 is an alkylene group having 2 to 4 carbon atoms,
The fixing solution according to claim 8 or 9, wherein R7 is an alkyl group having 1 to 4 carbon atoms.   8. An image forming means for forming an unfixed toner image on a recording medium by an electrostatic recording process using a toner in which resin fine particles contain a coloring material, and the fixing device according to any one of claims 1 to 7. An image forming apparatus for fixing a toner image on a recording medium.