JP2012063474A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device realizing fixation in low temperature so as to achieve energy saving as well as preventing occurrence of image blur and enabling secure fixation of toner image on a recording medium.SOLUTION: In an image formation device, before a toner image formed on an intermediate transfer belt 4 is transferred by a secondary transfer roller 7 onto a recording medium 9, a fixer liquid application unit 18 applies a fixer liquid on a surface of the recording medium 9 at a side on which the toner image is transferred, an excessive fixer liquid removal unit 30 removes excessively-applied part of the fixer liquid from the surface of the recording medium, the secondary roller 7 transfers the toner image onto the recording medium 9 on which the fixer liquid is applied, and a fixation unit 8 heats and pressurizes the toner image and the fixer liquid on the recording medium 9 so as to fix the toner image on the recording medium. The fixer liquid application unit 18 discharges the fixer liquid containing plasticizer having toner-softening/swelling function, and applies the fixer liquid on the recording medium 9.

Description

  The present invention relates to an image forming apparatus that forms or transfers a toner image on a recording medium and then fixes the image on the recording medium to obtain an image, that is, an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a digital multifunction machine.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a digital multifunction machine, a recording medium is formed by heating and melting a toner image formed or transferred on a recording medium such as transfer paper or recording paper by a fixing device Those using a heat fixing method for fixing on top are widely known.

In the thermal fixing method, a toner image on a recording medium is softened by heat and a pressure is applied so that the toner image is in close contact with the recording medium and fixed on the recording medium. At that time, in order to obtain a reliable fixing property, it is necessary that the toner in the portion in contact with the recording medium is sufficiently softened, and the surface of the recording medium is also heated to such an extent that the softened toner is not cured. There was a need.
However, although a large amount of electric power is required for sufficient heating, it is desired to lower the heating temperature of the fixing unit in order to save power in the entire image forming apparatus.

Therefore, Patent Document 1 discloses an image forming apparatus that employs a chemical fixing method in which a fixing solution that softens and / or swells toner is applied onto a toner image on a recording medium as a fixing method that does not use heat. ing.
Since this method does not use heat, significant power saving can be achieved as compared with the conventional heat fixing method. However, in this method, since the fixing solution is applied from above the toner image, a large amount of fixing solution is applied to reach the contact portion between the toner and the recording medium for reliable fixing. Image distortion may occur. In addition, there arises a problem that heating is necessary for drying.

In Patent Document 2, a fixing solution is applied to a toner image on an intermediate transfer member, the toner is changed into a sticky film, and the filmed toner is placed on a recording medium by its own stickiness. A method of transferring and fixing is shown.
This method also requires energy saving since it is not necessary to soften the toner by heat. However, even in this method, since the fixing liquid is applied to the toner on the intermediate transfer member, the toner image may be disturbed.

In addition, since the toner image is transferred to a recording medium by being formed into a film with a fixing solution and having adhesiveness, in order to form an image, the toner must be formed into a film in the use environment.
However, when the fixing solution is applied onto the intermediate transfer member, the fixing solution may scatter to the image forming portion that contacts the intermediate transfer member, and the function of the fixing solution may adversely affect the members in the machine. Conceivable.

  Further, in Patent Document 3, referred to as toner jet, direct toning, toner projection, etc., image formation of a system in which a toner image is directly recorded on a recording medium by causing the toner to fly and adhere to the recording medium. An apparatus is disclosed. And, by applying a coating liquid containing a softening agent that dissolves or swells the resin contained in the toner to the recording medium before the toner is adhered, the scattering of the toner at the time of image formation in the direct recording method is reduced, Further, it is described that the fixing is promoted.

  In this way, by applying a coating liquid containing a softening agent to the surface of recording paper as a recording medium in advance, the adhesion between the toner and the printing surface when the toner collides is increased, and toner scattering is suppressed. The repulsive force when the toner collides is reduced, and the scattering of the toner is improved.

In this case, since the fixing is promoted by the softener contained in the coating solution, the heating energy required for heat fixing can be greatly reduced, and the heating energy is not required by applying a sufficient coating solution. Is also described as possible.
However, in order to dissolve and swell the toner to give fixability, a considerable amount of the coating liquid needs to come into contact with the toner. However, since the flying toner directly adheres to the recording medium (recording paper), Only a very small amount of the coating solution on the surface contacts the toner.
Therefore, in order to dissolve and swell the toner and give fixing properties, it is essential to make more contact between the coating liquid and the toner.

  In such a conventional example, a fixing solution that dissolves and swells toner is used to reduce the fixing temperature or eliminate the need for heating for fixing. However, there is a concern that the fixing solution used in these adheres not only to the toner in the apparatus but also to the apparatus main body and dissolves and swells the resin used in the apparatus.

  Also, if the fixer is applied over the toner image, the image may be disturbed. If the fixer is applied before the toner image is carried on the recording medium, the fixer is effectively applied to the toner image. There is a problem that it may not work. Furthermore, when the fixing solution applied to the recording medium such as transfer paper is excessive, the amount of the fixing solution that wraps around the contact member in the post-process of image formation increases, which may increase the load on the system. .

  The present invention solves such a problem in the conventional image forming apparatus, realizes fixing at a low temperature to save energy, and does not cause image disturbance, and fixes a toner image onto a recording medium. An object of the present invention is to prevent the possibility that the fixing liquid adversely affects the resin in the image forming apparatus other than the toner and the load on the system increases.

The present invention provides an image forming apparatus that obtains an image by transferring a toner image onto a recording medium and then fixing the image on the recording medium. A fixing solution applying means for applying a fixing solution; an excess fixing solution removing means for removing a part of the fixing solution applied from the recording medium by the fixing solution applying means; and a recording medium coated with the fixing solution. Transfer means for transferring the toner image to the toner image, and fixing means for fixing the toner image to the recording medium by applying heat and pressure to the toner image on the recording medium and a fixing liquid,
The fixing solution applying means is a means for applying a fixing solution containing a plasticizer having a function of softening and swelling toner to a recording medium.

It is desirable that the plasticizer is a plasticizer that does not have a function of softening / swelling the toner sufficiently for fixing at room temperature, and has a function of softening / swelling the toner sufficiently for fixing when heated. More preferably, the plasticizer is solid at room temperature and has a melting point of 40 ° C. or higher.
Furthermore, it is desirable that the plasticizer is a compound containing an ethylene oxide group or a propylene oxide group.

  More preferably, the compound is any one of polyoxyethylene glycols, polyoxyethylene polyoxypropylene glycols, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene fatty acid diesters. .

The fixing solution preferably contains a surfactant for improving the permeability of the fixing solution into the toner layer. The surfactant is preferably a nonionic surfactant.
The solvent in the fixing solution is preferably ion exchange water.
The surplus fixing liquid removing unit may be disposed upstream of the transfer unit in the recording medium conveyance direction, and may include a removing member that contacts the surface of the recording medium on which the toner image is transferred.

  These image forming apparatuses include an image forming unit that forms a toner image on the surface of the photoconductor, and an intermediate transfer body onto which the toner image formed on the surface of the photoconductor is transferred by the image forming unit. The means may be means for transferring the toner image transferred onto the intermediate transfer member onto a recording medium.

The transfer unit may be a unit that directly transfers a toner image formed on the surface of the photoreceptor onto a recording medium.
Alternatively, a toner ejecting unit that directly forms a toner image on the intermediate transfer member may be provided, and the transfer unit may be a unit that transfers the toner image formed on the intermediate transfer member onto a recording medium.
The fixing unit may be a roller fixing unit including a fixing roller and a pressure roller.

  The image forming apparatus according to the present invention can achieve low-temperature fixing to save energy, and there is no risk of image disturbance, and the toner image can be reliably fixed on the recording medium. Images can be obtained. In addition, the possibility that the fixing liquid adversely affects the resin in the image forming apparatus other than the toner or the load on the system is greatly suppressed.

1 is a schematic diagram showing an overall configuration of a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of an image forming unit in FIG. 1. FIG. 2 is a schematic diagram illustrating a configuration example of a fixing liquid application unit in FIG. 1. FIG. 2 is a schematic diagram illustrating a configuration example of an excess fixing solution removing unit in FIG. 1. FIG. 4 is a diagram for explaining a difference in a state in which a fixing liquid soaks into toner when an image is formed on a recording medium in a non-contact manner and when the image is contact-transferred. FIG. 4 is a diagram for explaining that a plasticizer in a fixing solution softens a toner resin when the fixing solution soaked in toner receives heat. FIG. 5 is a conceptual diagram showing a relationship between a temperature and a storage elastic modulus when a liquid plasticizer is included in a fixing solution, when a solid plasticizer is included, and when a plasticizer is not included. It is a diagram showing the relationship between the temperature of the fixing roller and the smear ID in various types of fixing. It is a schematic diagram which shows the structure of the principal part of 2nd Example of the image forming apparatus by this invention. It is a schematic diagram which shows the structure of the principal part of 3rd Example of the image forming apparatus by this invention.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
[First embodiment]
FIG. 1 is a schematic diagram showing an example of an image forming apparatus embodying the present invention.
The image forming apparatus 100 includes four image forming units 1Y, 1C, 1M, and 1K for forming images of each color of yellow (Y), cyan (C), magenta (M), and black (K). Yes. Note that the color order of Y, C, M, and K is not limited to this order, but may be other order such as Y, M, C, and K.

  Each of these image forming units 1Y, 1C, 1M, and 1K includes photosensitive drums 2Y, 2C, 2M, and 2K as image carriers, and charging means, developing means, and cleaning means ( 2 will be described later with reference to FIG. Further, the arrangement of the image forming units 1Y, 1C, 1M, and 1K is predetermined so that the rotation axes of the photosensitive drums 2Y, 2C, 2M, and 2K are parallel to each other and in the moving direction of the recording medium (transfer sheet). It is set to be arranged at a pitch of.

  Below the image forming units 1Y, 1C, 1M, and 1K, a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like are provided, and on the surface of each photosensitive drum 2Y, 2C, 2M, and 2K based on the image data. An optical writing unit 3 that irradiates while scanning with a laser beam is provided, and an intermediate transfer body that rotates so as to superimpose and transfer toner images of the respective colors formed by the respective image forming units is provided above. A transfer belt 4 and primary transfer rollers 5Y, 5C, 5M, and 5K are disposed.

The primary transfer rollers 5Y, 5C, 5M, and 5K are opposed to the photosensitive drums 2Y, 2C, 2M, and 2K with the intermediate transfer belt 4 interposed therebetween.
A cleaning device 6 composed of a brush roller and a cleaning blade is disposed on the outer peripheral surface of the intermediate transfer belt 4 so as to come into contact therewith. The cleaning device 6 removes foreign matters such as transfer residual toner adhering to the intermediate transfer belt 4.

A secondary transfer roller 7 for transferring the toner image on the intermediate transfer belt 4 to a recording medium is disposed on the right end side of the intermediate transfer belt 4 in FIG.
In the first embodiment, each of the image forming units 1Y, 1C, 1M, and 1K is an image forming unit that forms a toner image on the surface of the photoconductor, and the toner image on which the intermediate transfer belt 4 is formed on the surface of the photoconductor. The intermediate transfer belt 4, the secondary transfer roller 7, and the driving roller 4 a of the intermediate transfer belt 4, which also serves as the secondary transfer counter roller, are transferred onto the recording medium coated with the fixing liquid. It constitutes transfer means for transferring the toner image.

Above the secondary transfer roller 7, a belt fixing type fixing unit 8 as a fixing unit is provided, and below the fixing unit 8 is a fixing solution applying unit 18 as a fixing solution applying unit.
The fixer application unit 18 contains a fixer containing a plasticizer having a function of softening and swelling the toner.

Between the secondary transfer roller 7 and the fixing liquid application unit 18, an excessive fixing liquid removal unit 30 which is an excessive fixing liquid removal means for removing the excessive fixing liquid is disposed. The excessively applied amount of the fixer applied on the surface is removed. The excess fixing liquid removing unit 30 includes a removing roller 31 and a pressure roller 32 which are removing members.
In the lower part of the image forming apparatus, there are provided two-stage paper feed cassettes 10a and 10b each storing a recording medium 9 which is a transfer sheet. Further, a manual feed tray 10c for manually feeding paper is provided on the side surface of the image forming apparatus.
In addition, toner replenishing containers 11Y, 11C, 11M, and 11K each containing toner of each color are provided, and a waste toner bottle and a power supply unit (not shown) are also provided.

The image forming units 1Y, 1C, 1M, and 1K all have the same configuration, and include a photosensitive unit 12 and a developing unit 13 that is a developing unit, as shown in FIG. A gap 14 in which the light L is incident is formed.
As shown in FIG. 2, the photosensitive unit 12 includes a photosensitive drum 2 (common to 2Y, 2C, 2M, and 2K), a charging roller 15 as a charging unit, a cleaning member 17 as a cleaning unit, and the like. The developing unit 13 is provided with a developing container 131 in which a developer is accommodated, a developing roller 132, a screw 133 for conveying and stirring the developer, a toner concentration sensor (not shown), and the like.

A developing container 131 of each of the image forming units 1Y, 1C, 1M, and 1K for each color accommodates a two-component developer composed of toner for developing each color of Y, C, M, and K and a magnetic carrier. The The developing roller 132 includes an outer rotatable sleeve and a magnet fixed on the inner side. Then, according to the output of the toner density sensor, toner is replenished from any of the toner replenishers 11Y, 11C, 11M, and 11K for each color.
Reference numeral 5 in FIG. 2 denotes a primary transfer roller that faces the photosensitive drum 2 with the intermediate transfer belt 4 interposed therebetween (common to 5Y, 5C, 5M, and 5K).

Next, the operation of this image forming apparatus will be described.
First, a predetermined voltage is applied to the charging roller 15 shown in FIG. 2 from a power source (not shown) to charge the surface of the opposing photosensitive drum 2. The surface of the photosensitive drum 2 charged to a predetermined potential is subsequently scanned with the laser light L based on the image data by the optical writing unit 3, and an electrostatic latent image is formed on the surface of the photosensitive drum 2. When the surface of the photosensitive drum 2 carrying the electrostatic latent image reaches the developing unit 13, toner is supplied to the electrostatic latent image on the photosensitive drum 2 by the developing roller 132 arranged to face the photosensitive drum 2. Thus, a toner image is formed.

Such an operation is similarly performed at a predetermined timing in all of the image forming units 1Y, 1C, 1M, and 1K shown in FIG. 1, and predetermined surfaces are respectively formed on the surfaces of the photosensitive drums 2Y, 2C, 2M, and 2K. A color toner image is formed.
The toner images on the photosensitive drums 2Y, 2C, 2M, and 2K are sequentially transferred onto the intermediate transfer belt 4 that rotates in the direction indicated by the arrow at the image forming operation timing of the image forming units 1Y, 1C, 1M, and 1K. Repeat and transfer. The toner image is transferred from a power supply (not shown) to primary transfer rollers 5Y, 5C, 5M, and 5K disposed opposite to the photosensitive drums 2Y, 2C, 2M, and 2K with the intermediate transfer belt 4 interposed therebetween. This is performed by applying a voltage having a polarity opposite to that of the toner on the drums 2Y, 2C, 2M, and 2K.

  The recording medium 9 is fed from one of the paper feed cassettes 10 a and 10 b or the manual feed tray 10 c shown in FIG. 1 by a paper feed roller (not shown), and then transported by a transport roller to reach the registration roller 16. At that point, it stops once. The recording medium 9 is conveyed from the registration roller 16 to the fixing liquid application unit 18 in accordance with the image forming operation timing described above. In FIG. 1, the alternate long and short dash lines Pa and Pb indicate the conveyance path of the recording medium 9, and Pb indicates the reverse conveyance path used for duplex printing.

  An example of the fixing liquid application unit 18 is shown in FIG. The fixing liquid application unit includes an application roller 19 and a counter roller 20. The recording medium 9 sent from the registration roller 16 is conveyed to the secondary transfer roller 7 through the nip between the application roller 19 and the counter roller 20. At the same time, the fixing roller 22 is supplied to the application roller 19 from a supply roller 21 immersed in the fixing solution 22 in the liquid chamber 23. As a result, the fixing liquid is applied to the recording medium when passing through the nip between the application roller 19 and the counter roller 20.

  The application roller 19 is disposed on the side to which the toner image is transferred during the secondary transfer, and the fixing liquid is applied in advance to the image surface side on which the toner image is transferred. According to the fixing liquid application unit 18, uniform application of the fixing liquid to the recording medium can be realized with a simple configuration.

  The excess fixing liquid removing unit 30 includes a removing roller 31 and a pressure roller 32 as shown in FIG. The removal roller 31 comes into contact with the surface of the recording medium on which the fixing solution is applied, and causes the excess fixing solution to adhere to the surface of the removal roller 31. In order to improve the contact between the surface of the removal roller 31 and the surface of the recording medium, a pressure roller 32 is arranged, and the removal roller 31 is opposed to the pressure roller 32 and is in pressure contact with the recording medium. ing. The function of the pressure roller 32 is to oppose the pressure and is not limited to the roller shape but may be a flat plate shape.

  The surface of the recording medium may have irregularities due to paper fibers or the like, and it is difficult to apply a necessary amount of the fixing liquid to the concave portions by one application from the application roller 19 of the fixing liquid application unit 18. When it is going to apply enough to a crevice, more fixer will adhere to a crevice. Therefore, as shown in this example, an excess fixing solution removing unit 30 is provided, and the application roller 19 is applied slightly excessively, and the removal roller 31 is used to remove the excess fixing solution. It can be easily applied.

  Further, the surface of the recording medium coated with the fixing liquid contacts the intermediate transfer belt 4 at the secondary transfer portion by the secondary transfer roller 7. At this time, excessive fixing solution may be transferred to the intermediate transfer belt 4 by contact and contaminate the inside of the apparatus. Therefore, before the recording medium comes into contact with the intermediate transfer belt 4 in the secondary transfer portion, the removing roller 31 is provided as a removing member that comes into contact with the surface of the recording medium, so that the fixing liquid is transferred to the removing roller 31 and the fixing liquid. 22 can reduce contamination in the apparatus.

  The secondary transfer roller 7 is disposed so as to contact the intermediate transfer belt 4 and to face the driving roller (also serving as a secondary transfer counter roller). The full-color toner image transferred while being superimposed on the intermediate transfer belt 4 is transferred to a recording medium at the nip portion between the secondary transfer roller 7 and the intermediate transfer belt 4. The transfer of the toner image is performed by applying a voltage having a polarity opposite to that of the toner on the intermediate transfer belt 4 from a power source (not shown) to the secondary transfer roller 7.

  When the toner image is contact-transferred to the recording medium, the fixing liquid 22 previously applied to the recording medium is soaked into the toner T from the recording medium 9 as shown in FIG. As a result, the toner T ′ that has been applied by the fixing liquid 22 (shown in black) is generated on the recording medium 9 side of the toner layer. Thereafter, the toner image is pressed and transferred while being in contact with the recording medium 9, whereby the capillary phenomenon becomes stronger than the non-contact image formation shown in FIG. 6A, and the fixing is performed as shown in FIG. Liquid penetration is encouraged.

  The fixing unit 8 includes a fixing roller 81 and a pressure roller 82. The recording medium onto which the toner image has been transferred receives heat and pressure at the nip between the fixing roller 81 and the pressure roller 82 to fix the image. At that time, in the nip, as shown in FIG. 6, the fixer 22 (shown in black) soaked in the toner T ′ receives heat, so that the plasticizer in the fixer 22 has a function of softening the toner resin. . The plasticizer penetrates into the toner layer near the interface with the recording medium 9 and permeates the toner resin and softens when triggered by the application of heat.

In other words, the toner image is fixed to the recording medium 9 at the nip between the fixing roller 81 and the pressure roller 82 by the plasticizer in the fixing liquid that exhibits not only heat but also a softening function. Since the plasticizer softens the toner in the vicinity of the interface with the recording medium 9 where heat is not easily transmitted, the control temperature of the fixing roller 81 is set to be lower than that of fixing only by heat fixing. Specific control temperature will be described later.
The recording medium 9 on which an image has been formed is carried out of the apparatus through one of the paths indicated by the alternate long and short dash line by a number of conveying rollers.

Here, the configuration and effects of characteristic portions in the image forming apparatus according to the present invention will be described.
The composition of the fixing solution 22 accommodated in the fixing solution application unit 18 shown in FIGS. 1 and 3 will be described. In the fixing liquid 22, a plasticizer and a surfactant are dissolved.
As the plasticizer, a plasticizer that does not have the function of softening / swelling the toner sufficiently for fixing at room temperature but has the function of softening / swelling the toner sufficiently for fixing when given heat is used. Is desirable. As the plasticizer, when a solid plasticizer having a melting point of 40 ° C. or higher is used as a plasticizer, as shown in a conceptual diagram of FIG. 7, when a fixing liquid containing a solid plasticizer is applied to the toner, The temperature at which the storage elastic modulus necessary for fixing the recording medium 9 to the recording medium 9 becomes small.
The normal temperature is 20 ° C. ± 15 ° C. (5-35 ° C.) in the Japanese Industrial Standard, and is a normal use environment temperature of the image forming apparatus.

Curve a in FIG. 7 shows a case where a fixer containing a liquid plasticizer having a softening ability at room temperature is applied to the toner, and curve b shows a fixer containing a solid plasticizer having almost no softening ability at room temperature. Curve c shows the case without a plasticizer.
In this embodiment, as a plasticizer to be included in the fixing solution, a solid plasticizer that has almost no softening ability at normal temperature and exhibits a softening function when given heat is used, thereby enhancing the effect of preventing in-machine contamination. . In particular, the resin member can be prevented from being adversely affected by the softening function of the solid plasticizer.

A solid plasticizer is a compound containing an ethylene oxide group — (CH ₂ CH ₂ O) — or a propylene oxide group — (CH (CH ₃ ) CH ₂ O) — in the molecular chain, and is generally a glycol ether or glycol fatty acid. Among what are called esters, the material is solid at room temperature and has a melting point of 40 ° C. or higher, desirably 50 ° C. or higher.
Specifically, polyoxyethylene glycols represented by the compound (1) are desirable.
_{HO- (CH 2 CH 2 O)} n-OH (1)

n is preferably 10 or more and 100 or less. When n is less than 10, it does not become solid at room temperature, and when n is greater than 100, the molecule becomes too large, and the plastic ability when heat is applied is low and the toner is difficult to soften. Specific examples of suitable materials include polyethylene glycol # 1000, polyethylene glycol # 1540, polyethylene glycol # 2000, polyethylene glycol # 4000, polyethylene glycol # 6000, polyethylene glycol # 8000, and the like.
Alternatively, polyoxyethylene polyoxypropylene glycols represented by the compound (2) are also desirable.
_{HO- (CH 2 CH 2 O)} n (CH (CH 3) CH 2 O) m-OH (2)

  n is preferably 10 or more and 200 or less. m is preferably 5 or more and 50 or less. When n is less than 10, it does not become a solid at room temperature, and when n is greater than 200, the molecule becomes too large, the plastic ability when heat is applied is low, and the toner is difficult to soften. When m is less than 5, it does not become solid at room temperature, and when m is greater than 50, the molecule becomes too large, and the plastic ability when heat is applied is low and the toner is difficult to soften. Specific examples of suitable materials include Emulgen 290 from Kao Corporation, Epan 450, Epan 750, Epan 785 from Daiichi Kogyo Seiyaku.

Alternatively, polyoxyethylene alkyl ethers represented by the compound (3) are also desirable.
_{R-O- (CH 2 CH 2} O) n-OH (3)
n is preferably 10 or more and 100 or less. When n is less than 10, it does not become solid at room temperature, and when n is greater than 100, the molecule becomes too large, and the plastic ability when heat is applied is low and the toner is difficult to soften.

  R is a linear alkyl group or a branched alkyl group, and the number of carbon atoms is preferably 10 or more and 22 or less. If it has less than 10 carbon atoms, it is soft as a solid, and there are safety problems such as skin irritation and eye irritation. When the number of carbon atoms is larger than 22, the plastic ability when heat is applied is low, and the toner is difficult to soften. Specific examples of suitable materials include Emulgen 350, Emulgen 420, and Emulgen 4085 from Kao Corporation, EMALEX 611, EMALEX 620, EMALEX 710, EMALEX 720 from Japan Emulsion Co., Ltd., and the like.

Furthermore, polyoxyethylene fatty acid esters and polyoxyethylene fatty acid diesters represented by compound (4) and compound (5) are also desirable.
_{R-COO- (CH 2 CH 2} O) n-OH (4)
_{R-COO- (CH 2 CH 2} O) n-COO-R '(5)

  n is preferably 10 or more and 100 or less. When n is less than 10, it does not become solid at room temperature, and when n is greater than 100, the molecule becomes too large, and the plastic ability when heat is applied is low and the toner is difficult to soften. R and R ′ are normal-type alkyl groups or branched-type alkyl groups, and preferably have 10 to 22 carbon atoms. If it has less than 10 carbon atoms, it is soft as a solid, and there are safety problems such as skin irritation and eye irritation. When the number of carbon atoms is larger than 22, the plastic ability when heat is applied is low, and the toner is difficult to soften. As specific materials, Emanon 3199V and Emanon 3299RV of Kao Corporation, EMALEX 820, EMALEX 830 of Japan Emulsion Co., Ltd., and the like are suitable.

  By including such a plasticizer in the fixing liquid, when heat is applied to the fixing unit, the toner softens and swells. However, the toner is softened and softened at the operating environment temperature (normal temperature) of the image forming apparatus. Since it does not have a function to swell and the plasticizer is solid, it is possible to suppress adverse effects when the plasticizer adheres in the image forming apparatus.

  The surfactant is used to improve the permeability of the fixing liquid into the toner layer. A nonionic surfactant is suitable as the surfactant. For example, polyoxyethylene alkyl ethers and acetylene surfactants are desirable. Specifically, polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene alkyl (12-14) ether (12E.O.), and polyoxyethylene alkyl (12-14) ether. As acetylene-based surfactants such as BT-12 of the company, acetylene glycol is excellent, and Olphine 1010 and Olphin 4051F manufactured by Nissin Chemical Industry Co., Ltd. are suitable.

  Water is suitable as a solvent (diluent) for these materials. Since city water contains many impurities such as calcium ions and magnesium ions, water from which these metal ions have been removed to some extent is desirable. However, the water does not need to be distilled water, and water obtained by removing impurity ions with an ion exchange membrane, so-called ion exchange water is suitable.

The image forming apparatus according to the present invention has improved smearing properties (toner smearing when rubbed) as compared with an image forming apparatus having a fixing configuration with only thermal fixing. Generally, the fixing lower limit temperature is set to a temperature that ensures a predetermined smear property.
FIG. 8 shows smear test results (friction test results) of an image forming apparatus (this example) in which a fixing solution is previously applied to a recording medium before image formation, and an image forming apparatus (conventional example) only for heat fixing. Indicates the smear ID. This fixing solution is a solution obtained by diluting polyethylene glycol # 2000 as a solid plasticizer and Olfin 4051F as a surfactant with ion-exchanged water to 25 wt% and 0.5 wt%, respectively.

This smear test was conducted using a smear tester (friction tester type I, JISL0823, friction element diameter: 15φ). A white cotton cloth (JIS L0803 cotton No. 3) of about 25 × 25 mm was attached to the friction element with a double-sided tape so that the fiber direction was horizontal with the moving direction of the friction element. Then, the evaluation image formed on the paper type: T6200 as a recording medium was rubbed in 5 reciprocations and continuously.
The evaluation images are a halftone image with an image area ratio of 55% and a 100% solid image. The white cotton cloth is peeled off, and the image density at any three locations on the friction mark where the image is adhered is measured using a spectrometer (X-Rite, 938 Spectrodensitometer), and the average value is smeared. ID. The lower the smear ID is, the less dirt is caused by the toner when the fixed image is rubbed. If it is 0.40 or less, it is acceptable for practical use.

  From FIG. 8, in the case of this embodiment, it is possible to ensure smearing at a setting temperature of the fixing roller of 121 ° C. for both the halftone image and the solid image. On the other hand, in the case of an image forming apparatus with only heat fixing, smearing cannot be secured unless the set temperature reaches 129 ° C. even for all solid images, and smear cannot be secured unless the set temperature reaches 139 ° C. for halftone images. Thus, in this embodiment, the fixing temperature is set to 121 ° C., which is 18 ° C. lower than that in the case of only thermal fixing.

  As described above, according to the present invention, since the control temperature of the fixing roller can be set low, power is saved and the image forming apparatus has a low environmental load. In this example, a fixing solution containing 25 wt% and 0.5 wt% of polyethylene glycol # 2000 as a solid plasticizer and 25 μ% of Olfine 4051F as a surfactant is used. However, the concentration of the plasticizer is adjusted. As a result, the temperature for ensuring smearing can be changed, so the fixing set temperature is not limited to this.

Here, details of the fixing liquid application unit 18 will be described below. As shown in FIG. 3, the fixing liquid application unit includes three rollers, that is, an application roller 19, an opposing roller 20, and a supply roller 21, and a liquid chamber 23 that stores the fixing liquid 22 and the fixing liquid.
Both the application roller 19 and the supply roller 21 have a diameter of 25 mm and employ a roller in which chloroprene is wound around a stainless steel core. The hardness of the roller is 35 degrees according to JIS-A. The coating roller 19 and the supply roller 21 are pressed by 20N on one side between the shafts at both ends in the longitudinal direction.

  A glass bead roller is adopted as the counter roller 20. A glass bead having a diameter of 100 μm is fixed to the surface thereof with an epoxy adhesive by a roller in which chloroprene is wound around a stainless steel core having a diameter of 25 mm. The opposing roller 20 is also pressurized by 20N on one side between the shafts at both ends in the longitudinal direction.

  The center of the coating roller 19 and the counter roller 20 is arranged at the same height. On the other hand, the supply roller 21 has its center at a position about 10 mm lower than the center of the application roller 19. The supply roller 21 is immersed in the fixing liquid 22 stored in the liquid chamber 23 by about 5 mm in a stationary state. Since the center of the supply roller 21 is offset in this way, when the recording medium enters the nip between the application roller 19 and the counter roller 2, the influence on the pressure between the application roller 19 and the supply roller 21 is affected. Can be reduced.

In these configurations, when the image forming operation is started, 170 mg of the fixing solution is applied to one A4 size plain paper recording medium (RICOPY PPC paper TYPE 6200 manufactured by Ricoh).
Next, the excess fixing solution removing unit 30 will be described in detail. As shown in FIG. 1, the surplus fixing solution removing unit 30 is arranged in the conveyance path of the recording medium 8 coated with the fixing solution by the fixing solution application unit 18. And as shown in FIG. 4, the removal roller 31, the pressurization roller 32, the braid | blade 33, and the container 34 are provided.

  The removal roller 31 has a configuration in which the surface of the silicone foam rubber is covered with a PFA tube and has a diameter of about 12 mm to 20 mm. The pressure roller 32 has the same diameter and is made of SUS. The removal roller 31 and the pressure roller 32 are configured to be pressurized. However, since the purpose is to bring the surface of the removal roller 31 into contact with the surface of the recording medium 8 as uniformly as possible, a large pressure is applied. Is not necessary.

  Similarly, in order to improve the contact property, the removing roller 31 is made of foamed rubber or the like to reduce the rubber hardness. Specifically, the surface hardness is about 30 to 65 degrees Asker C. In this embodiment, a pressure of 20 N on one side is applied to the removing roller 31 having a surface hardness of 50 degrees Asker C. However, the removal roller 31 can be made of a hard material such as a metal roller. In that case, it is necessary to make the pressure roller 32 of a soft material and ensure the contact between the removal roller 31 and the pressure roller 32.

  When the surface of the removing roller 31 comes into contact with the recording medium 8 coated with the fixing liquid, excess fixing liquid is attached to the surface. The surplus fixing solution removing unit 30 is provided with a blade 33 for removing the fixing solution adhering to the surface of the removing roller 31. In order to remove the fixing solution by the blade 33, it is desirable that the surface of the removing roller 31 is smooth, and a material having a low surface energy such as the PFA layer described above is desirable. When the removal roller 31 is made of metal, it is desirable to perform a process of smoothing the surface such as a mirror finish by surface processing.

The blade 33 is made of urethane rubber, silicone rubber or the like. In FIG. 4, the conveyance direction of the recording medium 8 is a direction from the bottom to the top, and the removal roller 31 and the pressure roller 32 rotate in the directions indicated by arrows A and B in FIG. The direction is opposite to the rotation direction of the removal roller 31, but may be a direction not opposite.
The fixing liquid removed from the surface of the removing roller 31 by the blade is dropped into the receiver 34 and then returned to the liquid chamber 23 of the fixing liquid application unit 18.

  It is also possible to remove the fixing liquid from the removal roller 31 by a method other than the blade. It can also be removed by a brush configured in a roll shape. In that case, unlike the case where the removal of the fixing liquid from the removal roller 31 is performed by a blade, the surface of the removal roller 31 does not need to be smooth. It is also possible to remove the fixing liquid from the surface of the removing roller by rubbing the web or the like. The pressure roller 32 is not necessarily a roller, and may be smoothly conveyed upward while the surface of the removal roller 31 is in good contact with the surface of the recording medium 9. Therefore, instead of the pressure roller 32, a fixing member having a smooth surface can be provided. In this case, there are advantages such as easy positioning and low cost compared to the case of using a movable roller.

  After applying about 170 mg of fixing solution per A4 size recording medium using the above-described fixing solution application unit 18 and passing through the excess fixing solution removal unit 30, the application amount of the fixing solution 22 is 40 to 50 mg. The degree was decreasing. In addition, when about 220 mg of fixer is applied to each A4 size recording medium using the fixer application unit 18 and then passed through the excess fixer removal unit 30, the weight is reduced by about 70 to 80 mg. It can be seen that excess fixer is removed.

  When the surplus fixing liquid coating unit 30 was passed, the fixability was good as in the case where it was not passed. Focusing on the uniformity of the fixing solution adhesion state, the fixing solution application unit 18 attaches 170 mg of fixing solution per A4 size recording medium, and then the excess fixing solution removal unit 30 removes excess fixing solution. As a result, a comparison is made between the case where 120 mg fixing solution is adhered per A4 size recording medium and the case where 120 mg fixing solution is applied only by the fixing solution application unit 18 by adjusting the amount of fixing solution applied. Then, when the coating was applied only with the fixing liquid coating unit, a defective fixing portion was found in the concave portion on the surface of the recording medium, whereas when the surplus fixing liquid removing unit 30 was used, the defective fixing was observed. I couldn't.

Accordingly, it has been found that the method of removing the excess fixing solution after applying the fixing solution in a slightly excessive manner is excellent in improving the uniformity of the fixing solution application.
According to the first embodiment, a high-resolution image can be formed by an electrophotographic method, and the fixing liquid can be infiltrated into the toner layer with a pressure during secondary transfer. In addition, since the intermediate transfer member is provided, it is possible to prevent the fixing liquid from flowing around the photosensitive member.

  Further, the excessive fixing liquid removing unit 30 serving as the fixing liquid removing means is disposed on the upstream side in the transport direction of the recording medium 9 from the secondary transfer portion by the secondary transfer roller 7, thereby holding the excessive fixing liquid. It is possible to prevent the transfer medium from entering the secondary transfer portion and to suppress the fixing liquid from adhering to the secondary transfer portion.

Further, the surplus fixing liquid removing unit 30 has a removing roller 31 as a removing member that comes into contact with the surface of the recording medium 9 on which the toner is transferred, so that the excessive fixing liquid can be efficiently removed.
Since the fixing unit 8 serving as the fixing unit is a roller fixing unit including a fixing roller 81 and a pressure roller 82, uniform heating can be realized with a simple configuration.

[Second Embodiment]
Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 9 is a configuration diagram schematically showing only a main part of the image forming apparatus, and shows an image forming unit, a fixing solution applying unit, an excess fixing solution removing unit, and a fixing unit. 9, parts corresponding to those in FIGS. 1 to 4 are denoted by the same reference numerals for convenience.

  In the first embodiment described above, the image forming unit is a quadruple tandem intermediate transfer system. However, the image forming unit of the second embodiment is a quadruple tandem direct transfer system. This image forming unit also includes four image forming units 1Y, 1C, 1M, and 1K for forming images of the respective colors. The configurations of these image forming units 1Y, 1C, 1M, and 1K are the same as those of the first embodiment described with reference to FIGS. 1 and 2, and each of the colors includes the photosensitive drums 2Y, 2C, 2M, and 2K. A charging unit, a developing unit, and a cleaning unit are provided around the photosensitive drums 2Y, 2C, 2M, and 2K.

Although not shown, the optical writing unit 3 is disposed below the image forming units 1Y, 1C, 1M, and 1K as in the first embodiment.
However, at the same position as the intermediate transfer belt 4 in the first embodiment, a transfer conveyance belt 40 that sucks and conveys a recording medium (in this case, recording paper) is provided instead, and the transfer conveyance belt 40 is sandwiched between them. Transfer rollers 50Y, 50C, 50M, and 50K are disposed at positions facing the photosensitive drums 2Y, 2C, 2M, and 2K, respectively.

  In this image forming unit, the recording medium 9 conveyed in the direction of arrow F1 at a predetermined timing from the left side of FIG. 9 is sucked by the transfer conveyance belt 40 and conveyed in the same direction, while each of the image forming units 1Y, 1C. The toner images of the respective colors formed by 1M and 1K are sequentially superimposed and transferred to form a full-color toner image directly on the recording medium 9. The recording medium 9 on which the full-color toner image is formed is further transported and discharged outside the apparatus after the image is fixed through a fixing device 8 having a fixing roller 81 and a pressure roller 82.

  In the second embodiment, a toner image is formed on a recording medium coated with a fixing liquid by image forming units 1Y, 1C, 1M, and 1K, a transfer conveyance belt 40, and transfer rollers 50Y, 50C, 50M, and 50K. The transfer means for directly transferring the image is configured.

Also in the second embodiment, along the recording medium conveyance path on the left side in FIG. 9 before the recording medium 9 enters the image forming section, the fixing liquid application unit 18 as fixing liquid application means and the removal of excess fixing liquid are performed. A removing roller 31 as a unit for removing the excess fixing liquid as means is disposed.
As in the first embodiment, the fixing liquid application unit 18 includes three rollers, that is, a supply roller 21, an application roller 19, and a counter roller 20, and a liquid chamber 23 that stores the fixing liquid 22.

  As shown in FIG. 9, the application roller 19 and the counter roller 20 are arranged perpendicular to each other. The supply roller 21 has its center at a position 10 mm downstream from the center of the application roller 19. The supply roller 21 is immersed 5 mm in the fixing liquid 22 stored in the liquid chamber 23. Since the centers of the application roller 19 and the supply roller 21 are offset in this way, when the recording medium 9 enters the nip between the application roller 19 and the opposing roller 20, the pressure applied to the supply roller 21 and the application roller 19 is increased. The influence of can be reduced. The configuration and material of the other rollers, the pressure applied between the rollers, and the like are the same as in the first embodiment.

  Near the downstream of the fixing liquid application unit 18 in the recording medium conveyance direction, a removal roller 31 constituting an excess fixing liquid removal unit is disposed so as to face the support roller 42 with the transfer conveyance belt 40 interposed therebetween. Yes. The removal roller 31 is provided with a member such as a blade (not shown) that removes the fixing liquid from the removal roller 31. The transfer / conveying belt 40 is stretched between a driving roller 41 and a support roller (driven roller) 42, and is rotated in the direction indicated by the arrow by the driving roller 41.

  As in the first embodiment, the recording medium 9 is fed and stopped once when it reaches a registration roller (not shown). Then, it is conveyed to the fixing liquid application unit 18 in accordance with the image forming operation timing. The recording medium 9 passes through the nip between the application roller 19 and the counter roller 20 and proceeds to a portion where the removal roller 31 faces the transfer conveyance belt 40, and is then sucked by the transfer conveyance belt 40 to each image forming unit 1Y, 1C, 1M. The toner images of the respective colors formed by the image forming units 1Y, 1C, 1M, and 1K are sequentially superimposed and directly transferred onto the lower surface of the recording medium 9 to form a composite color image.

  At that time, the fixing liquid 22 is supplied to the application roller 19 of the fixing liquid application unit 18 from the supply roller 21 immersed in the fixing liquid 22. As a result, when the recording medium 9 passes through the nip between the application roller 19 and the counter roller 20, the fixing liquid 22 is applied to the lower surface thereof, and then the excess fixing liquid is removed by the removal roller 31. The application roller 19 is disposed on the side to which the toner image is transferred during transfer to the recording medium 9, and the fixing liquid is the image surface side to which the toner image of the recording medium 9 is transferred (in FIG. 9). It is applied in advance to the lower surface side.

  Also according to the second embodiment, a high resolution image can be formed by an electrophotographic method, and the fixing solution can be soaked into the toner layer by the pressure at the time of transfer. In addition, since the intermediate transfer member is provided, space saving can be achieved.

[Third embodiment]
Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 10 is a configuration diagram schematically showing only a main part of the image forming apparatus, and shows an image forming unit, a fixing solution applying unit, an excess fixing solution removing unit, and a fixing unit. Also in FIG. 10, the same reference numerals are given to the portions corresponding to those in FIGS.
The main configuration of the image forming apparatus is the same as that of the first embodiment except for the fixing liquid application unit, the fixing device, and the recording medium conveying unit other than the image forming unit. Therefore, the image forming unit will be mainly described.

In the first embodiment described above, the image forming unit is an electrophotographic quadruple tandem intermediate transfer method. However, in the third embodiment, the image forming unit is a toner jet type quadruple tandem intermediate transfer method. .
In the image forming unit of this image forming apparatus, toner ejecting units 50Y, 50C, 50M, and 50K for each color are arranged side by side along the lower surface of the intermediate transfer belt 4 as image forming means.
Each of these toner ejecting units has the same structure except for the color of the toner to be used. Therefore, the structure of the toner ejecting unit 50Y will be briefly described as a representative.

The toner ejection unit 50Y includes a toner carrier 52 that carries toner T and rotates in a predetermined direction in a housing 51 that stores toner T (yellow toner), and a supply roller that supplies the toner T to the toner carrier. 53, a toner regulating blade 54 that contacts the surface of the toner carrier 52, and a toner control member 55 including a flexible printed circuit board in which a plurality of toner passage holes 55a through which charged toner passes are arranged. A back electrode 56 is disposed at a position facing the toner control member 55 with the intermediate transfer belt 4 interposed therebetween.
The configuration of the toner ejection unit 50Y and the like is the same as that of the image forming unit described in Patent Document 3 described above, for example.

  In the toner ejection unit 50Y and the like, the toner on the toner carrier 52 is frictionally charged by the toner regulating blade 54 and regulated to a predetermined thickness, and is transported to the flight start position facing the back electrode 56. A potential difference is applied between the toner carrier 52 and the back electrode 56 to form a transfer electric field that causes the charged toner to fly from the toner carrier 52 toward the back electrode 56. Further, the toner control member 55 applies a voltage according to an image signal to a control electrode provided around each toner passage hole 55 to electrostatically control the opening and closing of each toner passage hole 55. Accordingly, the charged toner is caused to fly (spray) toward the back electrode 56 through the toner passage hole 55 corresponding to the image signal, and is attached to the lower surface of the intermediate transfer belt 4 interposed therebetween to form a toner image.

Also in the third embodiment, yellow, cyan, magenta, and black are formed on the lower surface of the intermediate transfer belt 4 that rotates in the direction of the arrow by the toner ejecting units 24Y, 24C, 24M, and 24K of the image forming unit. The toner images are formed one after the other to form a full color toner image.
On the other hand, before the recording medium (transfer paper) 9 conveyed in the arrow F2 direction at a predetermined timing from the lower right side of FIG. 10 reaches the secondary transfer portion, the application roller 19 of the fixing liquid application unit 18 and Passes through the nip of the opposing roller 20. At that time, the fixing liquid 22 is applied to the left side of the recording medium 9 in FIG. 10, and then the excessive fixing liquid is removed by the removing roller 31 of the excess fixing liquid removing unit 30 ′.

  The surplus fixing solution removing unit 31 ′ of this embodiment is provided with a fixed pressure plate 35 having a smooth surface instead of the pressure roller 32 in the surplus fixing solution removing unit 30 of the first embodiment. The pressure plate 35 is easier to position and lower in cost than the pressure roller 32.

  In this way, the recording medium 9 having an appropriate amount of fixing solution applied to the surface on which the image is transferred is composed of a driving roller 4a (also serving as a transfer counter roller) 4a of the intermediate transfer belt 4 and a transfer roller 7 '. The full-color toner image formed on the intermediate transfer belt 4 is transferred to the recording medium 9 when passing through the transfer portions facing each other with the intermediate transfer belt 4 interposed therebetween. The transfer of the toner image is performed by applying a voltage having a polarity opposite to that of the toner on the intermediate transfer belt 4 from a power source (not shown) to the transfer roller 7 '.

The intermediate transfer belt 4 is stretched between a driving roller 4a and a support roller (driven roller) 4b, and is rotated in the direction of the arrow by the driving roller 4a.
The recording medium 9 onto which the full-color toner image has been transferred as described above is further transported and discharged outside the apparatus after the image is fixed through the fixing unit 8 having the fixing roller 81 and the pressure roller 82. The

In this third embodiment, each toner ejecting unit 50Y, 50C, 50M, 50K, intermediate transfer belt 4 and transfer roller 7 'constitute means for directly forming a toner image on the intermediate transfer member, and intermediate transfer The belt 4 and the driving roller 4a that also serves as a transfer counter roller and the transfer roller 7 'constitute transfer means for transferring the toner image onto the recording medium coated with the fixing liquid.
According to this embodiment, the present invention can be implemented with a simple configuration in which a toner image is directly formed on the intermediate transfer belt 4 as an intermediate transfer member, and a small and low-cost image forming apparatus can be provided. It becomes possible.

[Other Examples]
In each of the above-described embodiments, the fixing solution applying unit is configured to apply the fixing solution to the recording medium 9 by the applying roller 19 of the fixing solution applying unit 18. Instead, the fixing liquid is ejected (or ejected) from a number of nozzles or heads arranged in the width direction of the recording medium (a direction orthogonal to the transport direction), and the toner image on the recording medium is transferred to the surface. You may make it apply. By doing so, it is also possible to apply the fixing liquid only to the portion where the toner image on the surface of the recording medium is transferred.

As a result, the amount of the fixing solution used can be reduced, the fixing solution can be further prevented from adhering to and contaminating other parts of the apparatus, and the heating amount in the fixing unit 8 can be further reduced.
The present invention is not limited to those described in the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  The present invention relates to an image forming apparatus that forms or transfers a toner image on a recording medium and then fixes the image on the recording medium to obtain an image, that is, various image forming apparatuses such as a copying machine, a printer, a facsimile machine, and a digital multifunction machine. Applicable to.

1Y, 1C, 1M, 1K: Image forming units 2Y, 2C, 2M, 2K: Photosensitive drum (image carrier)
3: Optical writing unit 4: Intermediate transfer belt 4a: Driving roller 5Y, 5C, 5M, 5K: Primary transfer roller 6: Cleaning device 7: Secondary transfer roller 7 ': Transfer roller 8: Fixing unit 9: Recording medium ( 10a, 10b: paper feed cassette 10c: manual feed tray 11Y, 11C, 11M, 11K: toner supply container 12: photoconductor unit 13: developing unit 14: gap 15: charging roller 16: registration roller 17 : Cleaning member 18: Fixing liquid application unit 19: Application roller 20: Opposing roller 21: Supply roller 22: Fixing liquid 23: Liquid chamber 30, 30 ′: Excess fixing liquid removing unit 31: Removal roller 32: Pressure roller 33: Blade 34: Receptor 35: Pressure plate 40: Transfer conveyance belt 50Y, 50C, 50M, 50K: Toner jet Unit 81: fixing roller 82: the pressing roller 100: Image forming apparatus T: Toner

Japanese Patent No. 4224076 Japanese Patent No. 4354164 JP 2009-39977 A

It is desirable that the plasticizer is a plasticizer that does not have a function of softening / swelling the toner sufficiently for fixing at room temperature and has a function of softening / swelling the toner sufficiently for fixing when given heat. It is more preferable that the plasticizer is solid at room temperature and has a melting point of 40 ° C. or higher.
Furthermore, it is desirable that the plasticizer is a compound containing an ethylene oxide group or a propylene oxide group.

The fixing solution preferably contains a surfactant for improving the permeability of the fixing solution into the toner layer. The surfactant is preferably a nonionic surfactant.
The solvent in the fixing solution is preferably ion exchange water.
The surplus fixing liquid removing means is preferably disposed upstream of the transfer means in the recording medium conveyance direction, and has a removing member that contacts the surface of the recording medium on which the toner image is transferred .

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
[First embodiment]
FIG. 1 is a schematic diagram showing an example of an image forming apparatus embodying the present invention .
The image forming apparatus 100 includes four image forming units 1Y, 1C, 1M, and 1K for forming images of each color of yellow (Y), cyan (C), magenta (M), and black (K). Yes. Note that the color order of Y, C, M, and K is not limited to this order, but may be other order such as Y, M, C, and K.

A developing container 131 of each of the image forming units 1Y, 1C, 1M, and 1K for each color accommodates a two-component developer composed of toner for developing each color of Y, C, M, and K and a magnetic carrier. The The developing roller 132 includes an outer rotatable sleeve and a magnet fixed on the inner side. Then, according to the output of the toner density sensor, toner is supplied from any of the toner supply containers 11Y, 11C, 11M, and 11K for each color.
Reference numeral 5 in FIG. 2 denotes a primary transfer roller that faces the photosensitive drum 2 with the intermediate transfer belt 4 interposed therebetween (common to 5Y, 5C, 5M, and 5K).

The application roller 19 is arranged on the side to which the toner image is transferred during the secondary transfer, and the fixing liquid 22 is applied in advance to the image surface side to which the toner image is transferred. According to the fixer application unit 18, uniform application of the fixer 22 to the recording medium can be realized with a simple configuration.

The secondary transfer roller 7 is disposed so as to contact the intermediate transfer belt 4 and to face a driving roller (also serving as a secondary transfer counter roller) 4a . The full-color toner image transferred while being superimposed on the intermediate transfer belt 4 is transferred to a recording medium at the nip portion between the secondary transfer roller 7 and the intermediate transfer belt 4. The transfer of the toner image is performed by applying a voltage having a polarity opposite to that of the toner on the intermediate transfer belt 4 from a power source (not shown) to the secondary transfer roller 7.

The fixing unit 8 includes a fixing roller 81 and a pressure roller 82. The recording medium onto which the toner image has been transferred receives heat and pressure at the nip between the fixing roller 81 and the pressure roller 82 to fix the image. At that time, in the nip, as shown in FIG. 6, the fixer 22 (shown in black) soaked in the toner T ′ receives heat, so that the plasticizer in the fixer 22 has a function of softening the toner resin. . The plasticizer penetrates into the toner layer near the interface with the recording medium 9 and permeates the toner resin and softens when triggered by the application of heat.

This smear test was performed using a smear tester (friction tester type I, JIS L0823 , friction element diameter: 15φ). A white cotton cloth of about 25 x 25 mm (JIS)
L0803 Cotton No. 3) was affixed with a double-sided tape so that the fiber direction was horizontal with the moving direction of the friction element. Then, the evaluation image formed on the paper type: T6200 as a recording medium was rubbed in 5 reciprocations and continuously.
The evaluation images are a halftone image with an image area ratio of 55% and a 100% solid image. The white cotton cloth is peeled off, and the image density at any three locations on the friction mark where the image is adhered is measured using a spectrometer (X-Rite, 938 Spectrodensitometer), and the average value is smeared. ID. The lower the smear ID is, the less dirt is caused by the toner when the fixed image is rubbed. If it is 0.40 or less, it is acceptable for practical use.

Here, details of the fixing liquid application unit 18 will be described below. As shown in FIG. 3, the fixing liquid application unit 18 includes three rollers, an application roller 19, a counter roller 20, and a supply roller 21, and a liquid chamber 23 that stores the fixing liquid 22 and the fixing liquid.
Both the application roller 19 and the supply roller 21 have a diameter of 25 mm and employ a roller in which chloroprene is wound around a stainless steel core. The hardness of the roller is 35 degrees according to JIS-A. The coating roller 19 and the supply roller 21 are pressed by 20N on one side between the shafts at both ends in the longitudinal direction.

The center of the coating roller 19 and the counter roller 20 is arranged at the same height. On the other hand, the supply roller 21 has its center at a position about 10 mm lower than the center of the application roller 19. The supply roller 21 is immersed in the fixing liquid 22 stored in the liquid chamber 23 by about 5 mm in a stationary state. Since the center of the supply roller 21 is offset in this way, when the recording medium enters the nip between the application roller 19 and the counter roller 20, it affects the pressure applied between the application roller 19 and the supply roller 21. Can be reduced.

In these configurations, when the image forming operation is started, 170 mg of the fixing solution is applied to one A4 size plain paper recording medium (RICOPY PPC paper TYPE 6200 manufactured by Ricoh).
Next, the excess fixing solution removing unit 30 will be described in detail. As shown in FIG. 1, the surplus fixing liquid removing unit 30 is disposed in the conveyance path of the recording medium 9 coated with the fixing liquid 22 by the fixing liquid coating unit 18. As shown in FIG. 4, a removal roller 31, a pressure roller 32, a blade 33, and a receiver 34 are provided.

The removal roller 31 has a configuration in which the surface of the silicone foam rubber is covered with a PFA tube and has a diameter of about 12 mm to 20 mm. The pressure roller 32 has the same diameter and is made of SUS. Although the pressure is applied between the removal roller 31 and the pressure roller 32, the purpose is to make the surface of the removal roller 31 contact the surface of the recording medium 9 as uniformly as possible. Is not necessary.

When the surface of the removing roller 31 comes into contact with the recording medium 9 on which the fixing solution is applied, excess fixing solution is attached to the surface. The surplus fixing solution removing unit 30 is provided with a blade 33 for removing the fixing solution adhering to the surface of the removing roller 31. In order to remove the fixing solution by the blade 33, it is desirable that the surface of the removing roller 31 is smooth, and a material having a low surface energy such as the PFA layer described above is desirable. When the removal roller 31 is made of metal, it is desirable to perform a process of smoothing the surface such as a mirror finish by surface processing.

The blade 33 is made of urethane rubber, silicone rubber or the like. In FIG. 4, the conveyance direction of the recording medium 9 is a direction from the bottom to the top, and the removal roller 31 and the pressure roller 32 rotate in directions indicated by arrows A and B in FIG. Is a direction opposite to the rotation direction of the removal roller 31, but may be a direction not opposite.
The fixing liquid removed from the surface of the removing roller 31 by the blade is dropped into the receiver 34 and then returned to the liquid chamber 23 of the fixing liquid application unit 18.

It is also possible to remove the fixing liquid from the removal roller 31 by a method other than the blade. It can also be removed by a brush configured in a roll shape. In that case, unlike the case where the removal of the fixing liquid from the removal roller 31 is performed by a blade, the surface of the removal roller 31 does not need to be smooth. Further, it is possible to remove the fixing liquid from the surface of the removing roller 31 by rubbing the web or the like. The pressure roller 32 is not necessarily a roller, and may be smoothly conveyed upward while the surface of the removal roller 31 is in good contact with the surface of the recording medium 9. Therefore, instead of the pressure roller 32, a fixing member having a smooth surface can be provided. In this case, there are advantages such as easy positioning and low cost compared to the case of using a movable roller.

Even when the excess fixing liquid removing unit 30 was passed, the fixability was good as in the case where it was not passed. Focusing on the uniformity of the fixing solution adhesion state, the fixing solution application unit 18 attaches 170 mg of fixing solution per A4 size recording medium, and then the excess fixing solution removal unit 30 removes excess fixing solution. As a result, a comparison is made between the case where 120 mg fixing solution is adhered per A4 size recording medium and the case where 120 mg fixing solution is applied only by the fixing solution application unit 18 by adjusting the amount of fixing solution applied. Then, when the coating was applied only with the fixing liquid coating unit, a defective fixing portion was found in the concave portion on the surface of the recording medium, whereas when the surplus fixing liquid removing unit 30 was used, the defective fixing was observed. I couldn't.

Further, the excessive fixing liquid removing unit 30 serving as the fixing liquid removing means is disposed on the upstream side in the transport direction of the recording medium 9 from the secondary transfer portion by the secondary transfer roller 7, thereby holding the excessive fixing liquid. It is possible to prevent the transfer medium from entering the secondary transfer portion and to suppress the fixing liquid from adhering to the secondary transfer portion.

[Second Embodiment]
Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 9 is a configuration diagram schematically showing only a main part of the image forming apparatus, and shows an image forming unit, a fixing solution applying unit, a surplus fixing solution removing unit, and a fixing unit . 9, parts corresponding to those in FIGS. 1 to 4 are denoted by the same reference numerals for convenience.

Although not shown, the optical writing unit 3 is disposed below the image forming units 1Y, 1C, 1M, and 1K as in the first embodiment.
However, at the same position as the intermediate transfer belt 4 in the first embodiment, a transfer conveyance belt 40 that sucks and conveys a recording medium (in this case, recording paper) is provided instead, and the transfer conveyance belt 40 is sandwiched between them. Transfer rollers 5Y ′, 5C ′, 5M ′, and 5K ′ are arranged at positions facing the respective photosensitive drums 2Y, 2C, 2M, and 2K.

In this image forming unit, the recording medium 9 conveyed in the direction of arrow F1 at a predetermined timing from the left side of FIG. 9 is sucked by the transfer conveyance belt 40 and conveyed in the same direction, while each of the image forming units 1Y, 1C. The toner images of the respective colors formed by 1M and 1K are sequentially superimposed and transferred to form a full-color toner image directly on the recording medium 9. The recording medium 9 on which the full-color toner image is formed has the image fixed through a fixing unit 8 having a fixing roller 81 and a pressure roller 82, and is further conveyed and discharged outside the apparatus.

In the second embodiment, a recording medium coated with a fixing liquid by image forming units 1Y, 1C, 1M, and 1K, a transfer conveyance belt 40, and transfer rollers 5Y ′, 5C ′, 5M ′, and 5K ′. A transfer means for directly transferring the toner image is formed on the top.

Also according to the second embodiment, a high resolution image can be formed by an electrophotographic method, and the fixing solution can be soaked into the toner layer by the pressure at the time of transfer. Further, since no intermediate transfer member is provided, space can be saved.

[Third embodiment]
Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 10 is a configuration diagram schematically showing only a main part of the image forming apparatus, and shows an image forming unit, a fixing solution applying unit, an excess fixing solution removing unit, and a fixing unit . Also in FIG. 10, the same reference numerals are given to the portions corresponding to those in FIGS.
The main configuration of the image forming apparatus is the same as that of the first embodiment except for the fixing liquid application unit, the fixing device, and the recording medium conveying unit other than the image forming unit. Therefore, the image forming unit will be mainly described.

In the first embodiment described above, the image forming unit is an electrophotographic quadruple tandem intermediate transfer method. However, in the third embodiment, the image forming unit is a toner jet type quadruple tandem intermediate transfer method. .
In the image forming unit of this image forming apparatus, toner ejecting units 50Y, 50C, 50M, and 50K for each color are arranged side by side along the lower surface of the intermediate transfer belt 4 as image forming means . Each of these toner ejecting units has the same structure except for the color of the toner to be used. Therefore, the structure of the toner ejecting unit 50Y will be briefly described as a representative.

The toner ejecting unit 50Y carries a toner carrier 52 that carries the toner T and rotates in a predetermined direction in a housing 51 that stores toner T (yellow toner), and supplies the toner T to the toner carrier 52. A roller 53, a toner regulating blade 54 that contacts the surface of the toner carrier 52, a toner control member 55 including a flexible printed circuit board in which a plurality of toner passage holes 55a through which charged toner passes are arranged, and the like are provided. . A back electrode 56 is disposed at a position facing the toner control member 55 with the intermediate transfer belt 4 interposed therebetween.
The configuration of the toner ejection unit 50Y and the like is the same as that of the image forming unit described in Patent Document 3 described above, for example.

In the toner ejection unit 50Y and the like, the toner on the toner carrier 52 is frictionally charged by the toner regulating blade 54 and regulated to a predetermined thickness, and is transported to the flight start position facing the back electrode 56. A potential difference is applied between the toner carrier 52 and the back electrode 56 to form a transfer electric field that causes the charged toner to fly from the toner carrier 52 toward the back electrode 56. The toner control member 55, a voltage corresponding to the image signal to a control electrode provided around each toner passage hole 55a is applied to open and close controls each toner passage hole 55a electrostatically. Accordingly, the charged toner is caused to fly (spray) toward the back electrode 56 through the toner passage hole 55a corresponding to the image signal, and is attached to the lower surface of the intermediate transfer belt 4 interposed therebetween to form a toner image.

Also in the third embodiment, yellow, cyan, magenta, and black toners are formed on the lower surface of the intermediate transfer belt 4 that rotates in the direction of the arrow by the toner ejecting units 50Y, 50C, 50M, and 50K of the image forming unit. The images are sequentially overlapped to form a full color toner image.
On the other hand, before the recording medium (transfer paper) 9 conveyed in the arrow F2 direction at a predetermined timing from the lower right side of FIG. 10 reaches the secondary transfer portion, Passes through the nip of the opposing roller 20. At that time, the fixing liquid 22 is applied to the left side of the recording medium 9 in FIG. 10, and then the excessive fixing liquid is removed by the removing roller 31 of the excess fixing liquid removing unit 30 ′.

The surplus fixing solution removing unit 30 ′ of this embodiment is provided with a fixed pressure plate 35 having a smooth surface instead of the pressure roller 32 in the surplus fixing solution removing unit 30 of the first embodiment. The pressure plate 35 is easier to position and lower in cost than the pressure roller 32.

The intermediate transfer belt 4 is stretched between the driving roller 4a supporting rollers (driven rollers) 4b, the drive roller 4a thus is rotated in the arrowed direction.
The recording medium 9 onto which the full-color toner image has been transferred as described above is further transported and discharged outside the apparatus after the image is fixed through the fixing unit 8 having the fixing roller 81 and the pressure roller 82. The

Claims (13)

In an image forming apparatus that obtains an image by transferring a toner image onto a recording medium and then fixing the toner image on the recording medium.
Fixing solution applying means for applying a fixing solution onto the recording medium before the toner image is transferred, and excess fixing solution for removing a part of the fixing solution applied from the recording medium by the fixing solution applying means. Removing means; transfer means for transferring the toner image onto the recording medium coated with the fixing liquid; and applying the heat and pressure to the toner image and the fixing liquid on the recording medium to fix the toner image to the recording medium. Fixing means for causing
The image forming apparatus, wherein the fixing solution applying unit is a unit that applies a fixing solution containing a plasticizer having a function of softening and swelling toner to the recording medium.   The plasticizer is a plasticizer having a function of softening / swelling the toner sufficiently for fixing at normal temperature and a function of softening / swelling the toner sufficiently for fixing when given heat. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein the plasticizer is a plasticizer that is solid at normal temperature and has a melting point of 40 ° C. or higher.   The image forming apparatus according to claim 3, wherein the plasticizer is a compound containing an ethylene oxide group or a propylene oxide group.   The compound is any one of polyoxyethylene glycols, polyoxyethylene polyoxypropylene glycols, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene fatty acid diesters. The image forming apparatus according to claim 4.   The image forming apparatus according to claim 1, wherein the fixing solution includes a surfactant for improving the permeability of the fixing solution into a toner layer.   The image forming apparatus according to claim 6, wherein the surfactant is a nonionic surfactant.   The image forming apparatus according to claim 1, wherein the solvent in the fixing solution is ion-exchanged water.   The surplus fixing liquid removing means is disposed upstream of the transfer means in the recording medium conveyance direction, and has a removing member that contacts the surface of the recording medium on which the toner image is transferred. The image forming apparatus according to claim 1. The image forming apparatus according to any one of claims 1 to 9,
An image forming means for forming a toner image on the surface of the photoconductor, and an intermediate transfer body to which the toner image formed on the surface of the photoconductor by the image forming means is transferred,
An image forming apparatus, wherein the transfer means is means for transferring a toner image transferred onto the intermediate transfer body onto a recording medium.   The image forming apparatus according to claim 1, wherein the transfer unit is a unit that directly transfers a toner image formed on the surface of the photoreceptor onto a recording medium. The image forming apparatus according to any one of claims 1 to 9,
A toner ejecting means for directly forming a toner image on the intermediate transfer member;
An image forming apparatus, wherein the transfer means is means for transferring a toner image formed on the intermediate transfer member onto a recording medium.   The image forming apparatus according to claim 1, wherein the fixing unit is a roller fixing unit including a fixing roller and a pressure roller.