JP2016071057A - Fixation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixation device capable of securing fixation strength of toner on a transfer material and suppressing the offset and the like of toner.SOLUTION: A fixation device fixes on a transfer material a toner image developed with a liquid developer containing a toner and a carrier. The fixation device comprises a pressure imparting member that presses the transfer material having the toner image transferred thereon, and a non-contact heating device that is provided downstream of the pressure imparting member in the conveyance direction of the transfer material and heats the transfer material without contact therewith.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fixing device that fixes a toner image on a transfer material.

  In recent years, as an on-demand printing apparatus that requires high image quality and high resolution, such as commercial printing, a wet electrophotographic system that has a small toner particle diameter and can be printed at high speed has come to be used.

  In the wet electrophotographic system, a liquid developer in which toner is dispersed in a carrier liquid is used. Since the carrier liquid is used in this way, it is known that the carrier liquid in the toner or on the paper surface has a significant influence on the fixing of the toner onto the paper in the fixing step.

  Even when the contact fixing member is passed in a state where the carrier liquid is present in the toner, since the carrier liquid is contained, the heat capacity is large and the toner is not sufficiently softened. Furthermore, the carrier liquid acts to inhibit the bonding between the toners or the adhesion between the toner and the transfer material. For this reason, toner that cannot be sufficiently combined with other toners or toner that cannot be bonded to paper is transferred to the contact fixing member, and toner offset tends to occur.

  As a countermeasure, there is a technique in which a contact fixing member is acted after passing through a non-contact heating device. The role of the non-contact heating device is to apply heat energy to the toner layer containing the carrier liquid to soften and deform the toner and to discharge the carrier liquid from the toner layer. In this process, the carrier is not completely discharged and the toners are not bonded to each other, but the toners are easily bonded when passing through the contact fixing member at the next stage, and the toner is transferred to the contact fixing member. (Offset) is suppressed to some extent.

JP 2003-167456 A JP 2003-98864 A JP-A-4-311986

  However, the carrier liquid discharged from the toner layer temporarily stays on the upper surface of the toner layer or the transfer material surface, and the carrier liquid on the upper surface of the toner layer eventually moves to the transfer material surface over time. In this case, the carrier liquid on the surface of the transfer material inhibits the adhesion between the toner and the transfer material. For this reason, even if toner transfer (offset) is suppressed to some extent in the contact fixing member at the next stage, the problem of insufficient fixing strength has not been sufficiently solved.

  In general, it is difficult to remove the carrier liquid penetrating the transfer material surface in a short time. For example, a technique for adsorbing and removing the carrier liquid by contacting an adsorbing roller or the like is known, but even if the carrier liquid in the toner can be removed to some extent, the carrier liquid penetrates the surface of the transfer material. Cannot be removed in such a short time as to bring the roller into contact.

  In addition, an adsorbing roller needs to be adsorbed, and a porous material having high affinity for the carrier liquid is often used. For this reason, there has been a conflicting problem that when the toner layer is brought into contact with the toner layer, the toner moves to the adsorbing member together with the carrier liquid to disturb the image. SUMMARY OF THE INVENTION In view of the above-described circumstances, an object of the present invention is to provide a fixing device that can secure toner fixing strength on a transfer material and suppress toner offset and the like.

  The fixing device according to the present invention is a fixing device for fixing a toner image developed with a liquid developer containing toner and a carrier liquid onto a transfer material, and applying pressure to pressurize the transfer material onto which the toner image has been transferred. A member and a non-contact heating device that is provided downstream of the pressure applying member in the transport direction of the transfer material and heats the transfer material in a non-contact manner.

  According to this configuration, it is possible to secure the fixing strength of the toner to the transfer material and suppress the toner offset and the like. Hereinafter, unless otherwise specified, the upstream side and the downstream side in the conveyance direction of the transfer material are simply referred to as “upstream side” and “downstream side”.

  More specifically, the roller fixing device that heats and presses the transfer material may be provided on the downstream side of the non-contact heating device. More specifically, the above-described configuration may be a configuration in which an adjustment mechanism for adjusting the temperature of the pressure applying member to be lower than a predetermined temperature determined according to the type of the toner may be provided. The predetermined temperature may be a temperature defined by a softening point of the toner as measured by DSC.

  More specifically, as a configuration described above, a pre-heating device that heats the transfer material in a non-contact manner is provided on the upstream side of the pressure applying member, and the adjusting mechanism cools the pressure applying member. It is good also as a structure which performs the said adjustment.

  More specifically, the surface of the pressure applying member may be made of an oil-repellent material having a contact angle of the carrier liquid of 40 ° or more. More specifically, the pressure applying member may be configured to pressurize the transfer material at 200 to 3000 kPa.

  According to the fixing device of the present invention, it is possible to secure the fixing strength of the toner to the transfer material and suppress the toner offset and the like.

1 is a block diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. 1 is a configuration diagram of an image forming transfer device according to the present embodiment. FIG. FIG. 2 is a configuration diagram of a fixing device according to Configuration 1 according to the present embodiment. FIG. 6 is a configuration diagram of a fixing device according to Configuration 2 according to the present embodiment. It is explanatory drawing about the adjustment mechanism which concerns on this embodiment. It is explanatory drawing about the adjustment mechanism which concerns on this embodiment. It is explanatory drawing about the adjustment mechanism which concerns on this embodiment. It is a graph regarding the measurement result of the shoulder value of endothermic shift. FIG. 10 is a configuration diagram of a fixing device according to Configuration 3.

  Embodiments of the present invention will be described below with reference to the drawings. However, the content of the present invention is not limited to the embodiment.

  FIG. 1 is a block diagram illustrating a schematic configuration of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 includes a paper feeding device 3, an image transfer device 4, and a fixing device 5. The image forming apparatus 1 is a wet electrophotographic image forming apparatus (for example, a printer). As a basic operation, the image forming apparatus 1 receives input of image data from the outside (for example, a PC), and prints the image on a transfer material (for example, printing paper). To discharge to the outside.

  The paper feeding device 3 includes a tray or the like for storing a transfer material, and supplies a new transfer material to the image forming transfer device 4 in accordance with the transfer timing of the toner image. The image forming transfer device 4 performs processing (image forming processing) for creating a toner image based on input image data and processing (transfer processing) for transferring the toner image to a transfer material. The transfer material on which the toner image is transferred by the image forming transfer device 4 is conveyed to the fixing device 5.

  The fixing device 5 plays a role of fixing the toner image transferred to the transfer material to the transfer material. Printing is achieved by fixing the toner image, and the fixed transfer material is discharged from the image forming apparatus 1. Hereinafter, detailed configurations of the image forming transfer device 4 and the fixing device 5 will be described in order.

[Image transfer device]
First, the image forming transfer device 4 will be described. FIG. 2 is a configuration diagram of the image transfer device 4. As shown in the figure, the image transfer device 4 includes a photosensitive drum 41, a charging device 42, an exposure device 43, a liquid developing device 44, an intermediate transfer roller (intermediate transfer member) 45, a secondary transfer roller 47, and a photosensitive drum. A cleaning device 48a for the intermediate transfer roller and a cleaning device 48b for the intermediate transfer roller.

  In FIG. 2, only one liquid developing device 44 is disposed, but a plurality of liquid developing devices 44 may be disposed for color image formation. The color development method, the presence or absence of intermediate transfer, and the like can be arbitrarily set, and an arbitrary arrangement configuration corresponding thereto can be applied.

  First, the process around the photoreceptor will be described. The photosensitive drum 41 has a cylindrical shape with a photosensitive layer (not shown) formed on the surface thereof, and rotates in the direction of arrow A shown in FIG. A cleaning device 48 a, a charging device 42, an exposure device 43, a liquid developing device 44, and an intermediate transfer roller 45 are sequentially arranged on the outer periphery of the photosensitive drum 41 along the rotation direction of the photosensitive drum 41.

  The charging device 42 charges the surface of the photosensitive drum 41 to a predetermined potential. The exposure device 43 irradiates the surface of the photosensitive drum 41 with light, and lowers the charge level in the irradiated area to form an electrostatic latent image. The liquid developing device 44 develops the latent image formed on the photosensitive drum 41. That is, the liquid developer is transported to the developing area of the photosensitive drum 41, and the toner contained in the liquid developer is supplied to the electrostatic latent image on the surface of the photosensitive drum 41 to form a toner image.

  Next, the development process will be described. In this process, a developing bias voltage having the same polarity as the toner is applied to the developing roller of the liquid developing device 44 from a power source (not shown). Similarly, a difference in electric field is formed in balance with the potential of the latent image on the photosensitive drum 41 having the same polarity as that of the toner, and the toner in the liquid developer is electrostatically adsorbed on the photosensitive drum 41 according to the latent image, and the photosensitive member. The latent image on the drum 41 is developed.

  Next, the primary transfer process will be described. The intermediate transfer roller 45 is disposed so as to face the photosensitive drum 41, and rotates in the direction of arrow B shown in FIG. 2 while being in contact with the photosensitive drum 41. Primary transfer from the photosensitive drum 41 to the intermediate transfer roller 45 is performed at the nip portion between the intermediate transfer roller 45 and the photosensitive drum 41.

  In the primary transfer process, a transfer bias voltage having a polarity opposite to that of toner is applied to the intermediate transfer roller 45 from a power source (not shown). As a result, an electric field is formed between the intermediate transfer roller 45 and the photosensitive drum 41 at the primary transfer position, and the toner image on the photosensitive drum 41 is electrostatically adsorbed to the intermediate transfer roller 45, Is transcribed. When the toner image is transferred to the intermediate transfer roller 45, the cleaning device 48a removes the residual toner on the photosensitive drum 41, and the next image formation is performed.

  Next, the secondary transfer process will be described. The intermediate transfer roller 45 and the secondary transfer roller 47 are disposed so as to face each other with the transfer material X interposed therebetween, and rotate in contact with each other via the transfer material X. Secondary transfer from the intermediate transfer roller 45 to the transfer material X is performed at the nip portion between the intermediate transfer roller 45 and the secondary transfer roller 47.

  The transfer material X is conveyed to the secondary transfer position (in the direction of arrow C shown in FIG. 2) in synchronization with the secondary transfer timing. In the secondary transfer process, a transfer bias voltage having a polarity opposite to that of the toner is applied to the secondary transfer roller 47 from a power source (not shown). As a result, an electric field is formed between the intermediate transfer roller 45 and the secondary transfer roller 47, and the intermediate transfer roller 45 is transferred onto the transfer material X that has passed between the intermediate transfer roller 45 and the secondary transfer roller 47. The toner image is electrostatically attracted and transferred onto the transfer material X.

  Next, a liquid developer used for development will be described. In a liquid developer, colored toner particles are dispersed at a high concentration in a carrier liquid that is a solvent. In addition, additives such as a dispersant and a charge control agent may be appropriately selected and added to the liquid developer.

  As the carrier liquid, an insulating, non-volatile solvent at room temperature is used. Examples of the non-volatile solvent include silicon oil, mineral oil, and paraffin oil. The toner particles are mainly composed of a resin and a pigment or dye for coloring. This resin has a function of uniformly dispersing pigments and dyes in the resin and a function as a binder when being fixed to the transfer material X.

  In addition, as this resin, thermoplastic resins, such as a polystyrene resin, a styrene-acrylic resin, an acrylic resin, a polyester resin, an epoxy resin, a polyamide resin, a polyimide resin, a polyurethane resin, can be used, for example. A plurality of these resins may be mixed and used.

  Also, commercially available pigments and dyes used for coloring the toner can be used. For example, carbon black, bengara, titanium oxide, silica, phthalocyanine blue, phthalocyanine green, sky blue, benzidine yellow, lake red D, etc. can be used as the pigment. Solvent red 27, acid blue 9, or the like can be used as the dye.

  As a method for adjusting the liquid developer, it can be adjusted based on a commonly used technique. For example, the resin and the pigment are melt-kneaded using a pressure kneader, a roll mill, or the like at a predetermined blending ratio and uniformly dispersed, and the obtained dispersion is finely pulverized by, for example, a jet mill. Further, by classifying the obtained fine powder with, for example, an air classifier, a colored toner having a predetermined particle diameter can be obtained.

  Subsequently, the obtained toner is mixed with an insulating liquid as a carrier liquid at a predetermined blending ratio. This mixture can be uniformly dispersed by a dispersing means such as a ball mill to obtain a liquid developer. The volume average particle diameter of the toner is suitably in the range of 0.1 μm to 5 μm. When the average particle diameter of the toner is less than 0.1 μm, the developability is greatly lowered. On the other hand, when the average particle diameter exceeds 5 μm, the quality of the image is deteriorated.

  The ratio of the toner particle mass to the liquid developer mass is suitably about 10 to 50%. If it is less than 10%, the toner particles are liable to settle, and there is a problem with the stability over time during long-term storage. In addition, it is necessary to supply a large amount of liquid developer in order to obtain the required image density, the carrier liquid adhering to the paper increases, it must be dried during fixing, and steam is generated, causing environmental problems. . If it exceeds 50%, the viscosity of the liquid developer becomes too high, making it difficult to manufacture and handle.

  The viscosity of the liquid developer is preferably from 0.1 mPa · s to 10,000 mPa · s at 25 ° C. When the pressure is 10,000 mPa · s or more, it is difficult to handle the liquid developer such as stirring and feeding, and the burden on the apparatus for obtaining a uniform liquid developer is large.

[Fixing device]
Next, the fixing device 5 will be described. In the following description, the fixing device 5 will be described with reference to Configuration Mode 1 and Configuration Mode 2 (both examples of the configuration according to the present embodiment). The fixing device 5 according to the configuration form 1 is referred to as a “fixing device 5a”, and the fixing device 5 according to the configuration form 2 is referred to as a “fixing device 5b”.

  FIG. 3 is a configuration diagram of the fixing device 5a according to Configuration 1. As shown in the figure, the fixing device 5 a includes a roller fixing device 50, a non-contact heater 60, and a pressure applying member 80. These are arranged in order of the non-heating pressure applying member 80, the non-contact heater 60, and the roller fixing device 50 from the upstream side.

  The fixing device 5a includes a roller fixing unit 50 and a non-contact heater 60, which are heating and pressing units, as a plurality of heating units for fixing. A pressure applying member 80 is provided on the upstream side of the non-contact heater 60. The transfer material X carrying the unfixed toner image passes through the pressure applying member 80, receives heat radiation from the non-contact heater 60, and then passes through the roller fixing device 50 (contact heating means). .

  Next, the non-contact heater 60 which is a non-contact heating means will be described. In the non-contact heater 60, a heater 62 is installed in a heat insulating cover 61. The surface temperature of the heater 62 is controlled to a desired temperature by control means (not shown). In the non-contact heater 60, the transfer material X is transported by a recording paper transport unit (not shown) arranged on the non-image surface side.

  The heater 62 may be a long wavelength one such as a ceramic heater. The surface temperature of the ceramic heater is about 300 to 700 ° C. As a material of the heat insulating cover 61 for keeping the inside of the non-contact heater 60 at a high temperature, a high heat insulating and high heat resistant material such as ceramic fiber may be used.

  Next, the pressure applying member 80 will be described. The pressure applying member 80 is composed of two upper and lower rollers (81, 82). The pressure roller 81 that pressurizes the image is a metal roller, and the surface is composed of a PFA tube (thickness 10 to 50 μm). The material may be a fluorine-based material that is generally used as a release layer for a fixing roller or the like.

  The backup roller 82 is a metal roller, and an elastic layer is provided on the surface. As the material of this elastic layer, NRB, silicon rubber or the like may be used, and the thickness thereof is about 0.5 to 5.0 mm. Both rollers (81, 82) are rotatably supported, and the support portion of the pressure roller 81 has a structure in which pressure is applied by a spring in order to apply pressure when the transfer material X is sandwiched and conveyed. It has become. Arbitrary pressure can be applied by exchanging the spring.

  Next, the roller fixing device 50 that is a heating and pressing unit will be described. The roller fixing device 50 includes a fixing roller 51a and a pressure roller 51b. As shown in FIG. 3, the fixing roller 51a and the pressure roller 51b are arranged so that the rotation shafts are parallel to each other, and both ends in the axial direction are rotatably supported by bearing members (not shown).

  The pressure roller 51b is urged in the direction of the fixing roller 51a with a predetermined pressure contact force by a pressure mechanism (not shown) using a spring or the like, and a pressure nip portion is formed on the lower surface portion of the fixing roller 51a. . The pressure roller 51b is rotationally driven at a predetermined peripheral speed by a drive mechanism (not shown) so that the transfer material X is conveyed downstream (in the clockwise direction in FIG. 3). The fixing roller 51a rotates following the rotation of the pressure roller 51b due to the pressure frictional force with the pressure roller 51b at the pressure nip portion. Instead of this, the fixing roller 51a may be driven to rotate, and the pressure roller 51b may be driven to rotate.

  The fixing roller 51a and the pressure roller 51b have heater lamps 52a and 52b, respectively, and the surface temperature is controlled to a desired temperature by a control unit (not shown). The fixing roller 51a and the pressure roller 51b have a silicon rubber layer as an elastic layer for securing a nip width on the outer periphery of a metal core having a good thermal conductivity such as aluminum, and improve the surface releasability. For this purpose (for example, a PTFE or PFA fluorine resin release layer having a thickness of 10 to 50 μm).

  FIG. 4 is a configuration diagram of the fixing device 5b according to Configuration Mode 2. As shown in the figure, the fixing device 5b includes a roller fixing device 50, a non-contact heater 60, a pressure applying member 80, and a preheater 90 (preheating device). These are arranged in order of the pre-heater 90, the pressure applying member 80, the non-contact heater 60, and the roller fixing device 50 from the upstream side.

  The fixing device 5b includes a roller fixing unit 50, a non-contact heater 60, and a pre-heater 90, which are heating and pressing units, as a plurality of heating units for fixing. A pressure application member 80 is provided on the upstream side of the non-contact heater 60, and a preheater 90 is provided on the upstream side of the pressure application member 80. The transfer material X carrying the unfixed toner image sequentially passes through the pre-heater 90 and the pressure applying member 80, receives heat radiation from the non-contact heater 60, and then passes through the roller fixing device 50 (contact heating means). It is like that.

  Similar to the non-contact heater 60, the pre-heater 90 heats the transfer material X in a non-contact manner. The transfer material X can be heated in a stage before the pressure is applied by the pressure applying member 80 by the preheater 90. Since the roller fixing device 50, the non-contact heater 60, and the pressure applying member 80 are the same as those in the configuration mode 1, the description thereof is omitted here.

  Further, in any of the configuration modes 1 and 2, an adjustment mechanism for adjusting the temperature of the pressure applying member 80 is provided. As this adjustment mechanism, the thing of the form shown in each of FIGS. 5-7 is mentioned, for example.

  The adjustment mechanism shown in FIG. 5 is a mechanism that is provided with an exhaust fan and an intake fan and cools the pressure roller 81 and the backup roller 82. More specifically, the pressure roller 81 and the backup roller 82 are surrounded by a shield 83, and an exhaust fan and an intake fan are attached to the shield 83. The shield 83 is attached to block heat from other heating devices. Further, it is desirable that the intake fan be installed so as to perform intake from the outside of the image forming apparatus 1.

  The adjustment mechanism shown in FIG. 6 is a mechanism that is provided with a blower and an air pipe, and mainly cools the pressure roller 81. According to the adjusting mechanism, the air of the blower is guided to the vicinity of the pressure roller 81 by the air pipe, and the air is blown toward the pressure roller 81 from the air outlet of the air pipe. The adjustment mechanism may be configured to blow air also to the backup roller 82.

  The adjustment mechanism shown in FIG. 7 is a mode in which a cooling liquid circulation device (chiller) is provided and a pressure roller 81a capable of passing a cooling liquid (water, etc.) is employed. The cooling liquid inlet and outlet of the pressure roller 81a are connected to a cooling liquid circulation device, whereby the cooling liquid can be circulated through the pressure roller 81a to cool the pressure roller 81a. Note that the adjustment mechanism may be configured to circulate the coolant also in the backup roller 82.

  In addition, the inventors conducted experimental evaluation on various examples and comparative examples described later. First, the procedure and conditions for the experiment evaluation will be described.

[About toner softening point]
First, a method for measuring the softening point of the toner will be described. The liquid developer is applied on a support such as a tile so as to have a thickness of 2 to 3 μm, and is allowed to stand at room temperature and normal pressure for 24 hours to obtain a dry solid of the liquid developer on the support. Next, 20 mg of this solid was weighed and used as a measurement sample.

  Subsequently, this measurement sample and 20 mg of alumina as a reference were set in a differential scanning calorimeter (trade name: “DSC-6200”, manufactured by Seiko Instruments Inc.), and under a nitrogen gas atmosphere (30-50 ml / min) The mixture was heated from room temperature to 200 ° C. under a temperature rising rate of 10 ° C./min. Thereafter, after cooling to 0 ° C. at 30 ° C./min, the shoulder value of the endothermic shift was measured by raising the temperature again at a temperature rising rate of 10 ° C./min.

  An example of the measurement result of the shoulder value of the endothermic shift is shown in FIG. The vertical axis indicates the heat flow, and the horizontal axis indicates the temperature. The shoulder value of this endothermic shift is in the range of 30 to 100 ° C. when the temperature is increased for the second time. The temperature was defined as the softening point (the temperature defined by the softening point of the toner as measured by DSC, the temperature indicated by “a” in the figure).

  For toner A and toner B used in Examples and Comparative Examples described later, the softening point measurement results were obtained that the softening point of toner A was 65 ° C. and the softening point of toner B was 75 ° C. In the present embodiment, the temperature of the pressure applying member 80 is adjusted to a temperature lower than the softening point by the adjusting mechanism (see FIGS. 5 to 7) described above.

[Pressure measurement method]
Next, a method for measuring the pressure of the pressure applying member 80 will be described. A commercially available pressure distribution measuring device (PINCH manufactured by Nitta Corporation) was used for the pressure measurement. The sensor is a sheet type sensor (PINCH A3-40) having a thickness of 180 to 200 μm and a horizontal width direction of about 320 mm, and generally matches the thickness of the paper. This was held between rollers, and the peak value of pressure was measured. It should be noted that when the nip length of the pressure applying member 80 is 1 mm or less, it cannot be measured due to sensor resolution limitations.

[Contact angle measurement method]
Next, a method for measuring the contact angle of the carrier liquid on the surface of the pressure applying member 80 (contact portion with the transfer material X) will be described. DM700 made by Kyowa Interface Science was used for the measurement of the contact angle, and “Teflon (registered trademark) 18G” was used for the liquid discharge needle. Using this, the following surface layer materials used in the examples described later were measured. In addition, the solvent used for the measurement is Ip2028 (Idemitsu Kosan).
・ Surface material 1 (PFA): 40.5 °
-Surface layer material 2 (PTFE): 34.0 °
・ Surface material 3 (fluorine-based paint): 23.5 °

[Conditions of Examples and Comparative Examples]
Next, the conditions of each Example (Examples 1 to 10) and each Comparative Example (Comparative Examples 1 to 12) for which the experimental evaluation was performed will be described in order.

<Example 1>
In Example 1, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner A described above was used as the toner. Regarding the roller diameter of the pressure applying member 80, both the pressure roller 81 and the backup roller 82 have a diameter of 100 mm. As the surface layer material of the pressure roller 81, the surface layer material 1 which is PFA was used. The rubber thickness of the backup roller 82 was 3 mm. The rubber material was NBR, and the hardness was 60 ° (JISK6253).

The peak pressure of the pressure applying member 80 was set to 200 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. The transfer material X used is of three types: transfer material 1 (gold rhombus 209g), transfer material 2 (gold rhombus 127.9g), and transfer material 3 (SA gold wisteria 209.3). As the liquid developer, polyester toner particles and liquid paraffin IP2028 (produced by Idemitsu Kosan Co., Ltd.) as a carrier liquid were used. A solid patch of 15 mm × 100 mm was prepared as an image, and the adhesion amount was set to ² g / m ² in terms of liquid developer solid content.

  For the output of the non-contact heater 60, a non-contact thermometer was used at the outlet, and the driving power was adjusted so that the temperature of the solid patch portion was about 70 ° C. For the setting of the roller fixing device 50, similarly, a non-contact thermometer is installed at the outlet of the fixing device, and the driving power capable of producing four levels of temperatures of the solid patch portion of 100 ° C., 110 ° C., 120 ° C., and 130 ° C. It was investigated and the evaluation was conducted at these four levels in the experimental evaluation.

  Here, the evaluation method will be described. First, with respect to the fixing strength, a tape peeling test was performed on a solid patch image at an outlet paper temperature of 100 ° C. of the roller fixing device 50. The tape used was Scotch mending tape (model number 810-1-18D). The level at which the toner image was peeled off after the tape was applied immediately after fixing was sensory evaluated. “R3 (Rank 3)” when the tape is not peeled off at all, “R2 (Rank 2)” when even a little toner is attached to the tape, and “R1 (Rank 1)” where the substrate of the transfer material X can be seen. ". R3 is the best evaluation, and it can be said that the evaluation becomes worse as R2 and R1 are obtained.

  In addition, regarding the transfer to the pressure applying member 80, the toner that would have adhered by attaching the transparent tape to the pressure applying member 80 after the experiment was collected, and the toner on the transparent tape was examined using an optical microscope. . If adhesion was recognized, the evaluation was “x”, and if it was not observed, the evaluation was “◯”. As the transparent tape, “Amenity B-Coat T” (Kihara Corporation, model number 894100) was used.

  Regarding the offset evaluation, the offset was examined at each temperature level of roller fixing. The investigation method was a method in which a white paper was passed immediately after each experiment, the toner transferred to the fixing roller was re-transferred to the white paper, and this was visually confirmed. If retransfer to blank paper was observed, the evaluation was “x”, and if not, the evaluation was “◯”.

<Example 2>
In Example 2, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. Other conditions are the same as in the first embodiment.

<Example 3>
In Example 3, the fixing device 5a having the configuration 1 (see FIG. 3) is applied, and the toner A is used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 60 ° C. Other conditions are the same as in the first embodiment.

<Example 4>
In Example 4, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 3000 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. Other conditions are the same as in the first embodiment.

<Example 5>
In Example 5, the fixing device 5b having the configuration 2 (see FIG. 4) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 200 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. Regarding the setting of the pre-heater 90, a non-contact thermometer is installed at the outlet of the pre-heater 90, and the temperature of the solid patch portion is checked while the transfer material X is actually passed through. Thus, the power applied to the preheater 90 was adjusted. Other conditions are the same as in the first embodiment.

<Example 6>
In Example 6, the fixing device 5b having the configuration 2 (see FIG. 4) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. The other conditions are the same as in Example 5.

<Example 7>
In Example 7, the fixing device 5b having the configuration 2 (see FIG. 4) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 3000 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. The other conditions are the same as in Example 5.

<Example 8>
In Example 8, the fixing device 5b having the configuration 2 (see FIG. 4) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 60 ° C. The other conditions are the same as in Example 5.

<Example 9>
In Example 9, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner B was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 60 ° C. The other conditions are the same as in Example 5.

<Example 10>
In Example 10, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner B was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 70 ° C. The other conditions are the same as in Example 5.

<Comparative Example 1>
In Comparative Example 1, the fixing device 5a of Configuration Mode 1 (see FIG. 3) from which the pressure applying member 80 was removed was applied, and the toner A was used as the toner. Other conditions are the same as in the first embodiment.

<Comparative Example 2>
In Comparative Example 2, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 65 ° C. Other conditions are the same as in the first embodiment.

<Comparative Example 3>
In Comparative Example 3, the fixing device 5a of Configuration Mode 1 (see FIG. 3) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 70 ° C. Other conditions are the same as in the first embodiment.

<Comparative example 4>
In Comparative Example 4, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 100 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. Other conditions are the same as in the first embodiment.

<Comparative Example 5>
In Comparative Example 2, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 150 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. Other conditions are the same as in the first embodiment.

<Comparative Example 6>
In Comparative Example 6, a configuration obtained by removing the pressure applying member 80 from the fixing device 5b of Configuration Mode 2 (see FIG. 4) was applied and compared with Examples 5 to 7. As the toner, toner A was used. The other conditions are the same as in Example 5.

<Comparative Example 7>
In Comparative Example 7, the fixing device 5b having the configuration 2 (see FIG. 4) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 150 kPa, and the temperature of the pressure applying member 80 was set to about 60 ° C. The other conditions are the same as in Example 5.

<Comparative Example 8>
In Comparative Example 8, the fixing device 5b of Configuration Mode 2 (see FIG. 4) was applied, and the toner A was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 65 ° C. The other conditions are the same as in Example 5.

<Comparative Example 9>
In Comparative Example 9, the fixing device 5a of Configuration 1 (see FIG. 3) was applied, and the toner B was used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 75 ° C. The other conditions are the same as in Example 5.

<Comparative Example 10>
In Comparative Example 10, the fixing device 5c (configuration in which the pressure applying member 80 is disposed on the downstream side of the non-contact heater 60) having the configuration 3 shown in FIG. 9 is applied, and the toner A is used as the toner. Further, the pressure of the pressure applying member 80 was set to 1000 kPa, and the temperature of the pressure applying member 80 was set to about 30 ° C. Other conditions are the same as in the first embodiment.

<Comparative Example 11>
In Comparative Example 11, the fixing device 5a of Configuration Mode 1 (see FIG. 3) was applied, and the surface layer material 2 described above was used as the surface layer of the pressure applying member 80. Other conditions are the same as in the second embodiment.

<Comparative Example 12>
In Comparative Example 12, the fixing device 5a of Configuration Mode 1 (see FIG. 3) was applied, and the surface layer material 3 described above was used as the surface layer of the pressure applying member 80. Other conditions are the same as in the second embodiment.

[About evaluation results]
Table 1 summarizes the setting conditions and evaluation results of all examples and comparative examples. In addition, about the evaluation result of offset, the result about the transfer material 1 is shown. Each item found from the evaluation results shown in Table 1 will be described below.

<Effect of pressure applying member>
When the comparative example 1 (when the pressure applying member 80 is removed in the configuration form 1) and the examples 1, 2, and 4 are compared, it is recognized that the presence of the pressure applying member 80 has a great effect on the fixing strength. On the other hand, from the results of Comparative Examples 4 and 5, even when the pressure applying member 80 is present, the effect is not sufficiently exhibited when the pressure does not reach 200 kPa. Moreover, the same thing can be said also in the configuration form 2, and when the comparative example 6 and Examples 5, 6, and 7 are compared, the effect of the pressure application member 80 is recognized. Further, from the result of Comparative Example 7, even when the pressure applying member 80 is present, the effect is small when the pressure does not reach 200 kPa.

<Position of pressure applying member>
Comparing Comparative Example 10 (when the pressure applying member 80 is disposed on the downstream side of the non-contact heater 60) and Example 2, the non-contact heater 60 (non-contact heating member) is disposed on the downstream side of the pressure applying member 80. It can be said that better effects can be obtained in terms of offset and the like.

<Temperature setting of pressure applying member>
In the toner A having a softening point near 65 ° C., the toner transfer is suppressed by setting the temperature of the pressure applying member 80 to less than 65 ° C. from the results of Examples 2 and 3 and Comparative Examples 2 and 3. I understand that. Further, there is almost no difference depending on the configuration form, and the same can be said in the configuration form 2 from the results of Examples 6 and 8 and Comparative Example 8. It can be seen from the results of Examples 9 and 10 and Comparative Example 9 that toner B having a softening point near 75 ° C. still needs to set the temperature of the pressure applying member 80 below the softening point.

<Surface layer material of pressure applying member>
From the results of Example 2 and Comparative Examples 11 and 12 in which the surface layer material of the pressure roller 81 is different, toner transfer is observed in the surface layer materials 2 and 3, but in the case of the surface layer material 1, there is no toner transfer. From this, it can be said that the surface portion (contact portion with the transfer material X) of the pressure applying member is desirably made of an oil repellent material having a contact angle of the carrier liquid of at least 40 ° or more.

[Others]
The fixing device 5 according to the present embodiment can be set so as to satisfy any one of the conditions in Examples 1 to 10 described above or a condition based thereon. The fixing device 5 is a fixing device that is employed in a wet electrophotographic method using a liquid developer containing toner and a carrier liquid and fixes a toner image on the transfer material X. The fixing device 5 includes a pressure applying member 80 that pressurizes the transfer material X to which the toner image is transferred, and a non-contact heater 60 that is provided on the downstream side of the pressure applying member 80 and heats the transfer material X in a non-contact manner. I have. Therefore, the fixing device 5 can secure the fixing strength of the toner to the transfer material X and suppress the toner offset and the like.

  In the fixing device 5, a roller fixing device 50 that heats and presses the transfer material X is provided on the downstream side of the non-contact heater 60. Further, in the fixing device 5, an adjustment for adjusting the temperature of the pressure applying member 80 to be lower than a temperature defined by the softening point of the toner as measured by DSC (a predetermined temperature determined according to the type of toner). A mechanism is provided. The surface of the pressure applying member 80 is made of an oil-repellent material having a carrier liquid contact angle of 40 ° or more, and the pressure applying member 80 pressurizes the transfer material X at 200 to 3000 kPa. In the fixing device 5b of Configuration Mode 2, a preheater 90 for heating the transfer material X in a non-contact manner is provided on the upstream side of the pressure applying member 80. Further, the adjusting mechanism adjusts the pressure applying member 80 to be lower than the softening point of the toner by cooling the pressure applying member 80.

  In addition, the fixing device according to the present embodiment has an excellent effect as compared with Patent Documents 1 to 3 described above. This point will be described in more detail for each patent document.

  Patent Document 1 (Japanese Patent Laid-Open No. 2003-167456) discloses a method in which an image is transferred to a transfer material, heated by a first-stage contact heating member on the downstream side, and then a carrier liquid on a toner layer. Is brought into contact with the blotter roller to adsorb and remove the carrier liquid. As a result, the carrier liquid in the toner layer is removed to some extent, so that the fixing strength can be increased by the second-stage contact fixing member as the subsequent stage.

  However, even if the transferred toner layer is suddenly passed through the contact heating member, the carrier liquid still exists in the toner layer, and the toner is not sufficiently bonded. Therefore, the toner easily shifts (offset) to the contact heating member, and the image is disturbed. In addition, the blotter roller has the effect of adsorbing and collecting the carrier liquid on the toner layer, but does not promote the coupling between the toners. Will pass. As a result, it is difficult to say that sufficient fixing strength can be obtained.

  On the other hand, according to the present embodiment, the pressure applying member acts after the transfer. The member is different from the above-described blotter roller in that it does not adsorb and collect the carrier liquid. The carrier liquid in the toner layer is forcibly permeated in the thickness direction of the transfer material by the action of pressure. As a result, not only the carrier liquid in the toner layer but also the carrier liquid concentration at the interface between the toner layer and the transfer material (transfer material surface) is effective.

  One of the features of the fixing device of the present embodiment is that a great amount of pressure is applied in order to exert the same effect. One of the features is that the surface layer is made of an oil-repellent material in order to suppress toner transfer to the pressure applying member, which is also a side effect. In the present embodiment, unlike the case of Patent Document 1, it is difficult for the carrier liquid to adhere and toner transfer hardly occurs. Furthermore, it is one of the features of this embodiment that the temperature of the pressure applying member is set to be equal to or lower than the softening point of the toner. This also contributes to suppressing toner transfer.

  The factor of the effect on the fixing strength of the present embodiment is that a non-contact heating unit is provided on the downstream side of the pressure applying member in addition to the above-described device for applying the pressure. To explain this effect, the carrier liquid in the toner layer is dispersed in the thickness direction of the transfer material by the pressure applying member, and there is almost no carrier liquid in the toner layer. In addition, the carrier liquid concentration on the surface of the transfer material is also reduced. It is dispersed in the thickness direction of the transfer material, resulting in a low concentration. In this state, when the non-contact heating means is passed, the bonding between the toners progresses drastically, and further, an adhesive force is developed between the toner and the transfer material. Compared to the state of the toner layer before entering the final stage contact fixing member in Patent Document 1, it is clear that the present embodiment can increase the fixing strength.

  Also, in the device disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2003-98864), after an image is transferred to a transfer material, it is first heated by a non-contact heating means on the downstream side. Thereafter, the carrier liquid on the toner layer is brought into contact with the blotter roller to remove the carrier liquid by adsorption. Since the carrier liquid in the toner layer is removed to some extent, the fixing strength can be increased by the subsequent contact fixing member. This technique is an improvement of the technique of Patent Document 1 and improves image disturbance at the first-stage contact heating member that is likely to occur when a transfer material that does not easily penetrate the carrier liquid is used. Instead of contact heating means. The object of the invention and the action of the blotter roller are the same as in Patent Document 1.

  In the technique of Patent Document 1, toner transfer is likely to occur in the first-stage contact heating member, but in the technique of Patent Document 2, transfer does not occur due to non-contact heating. However, although this point is improved, other than that, Patent Document 2 still has the same problem as Patent Document 1. That is, even if the carrier liquid after transfer is suddenly passed through the non-contact heating means, the toners are not sufficiently coupled. Since the blotter roller does not have a function of coupling the toner, the blotter roller enters the second stage contact fixing member in a state where the toner is not sufficiently coupled. Also, the carrier liquid concentration on the surface of the transfer material is lower in this embodiment, and this embodiment is more advantageous in terms of fixing strength, including the viewpoint of the adhesive force between the toner and the transfer material.

  In addition, what is disclosed in Patent Document 3 (Japanese Patent Application Laid-Open No. 4-311986) transfers an image to a transfer material and contacts a blotter roller on the downstream side to remove the carrier liquid by adsorption. Since the carrier liquid in the toner layer is removed to some extent, image disturbance on the subsequent contact fixing member is prevented. However, in the technique of Patent Document 3, a blotter roller is applied to the toner layer containing the carrier liquid after the transfer to collect the carrier liquid on the toner layer, but it does not have a function of bonding between the toners. Thus, the toner enters the contact fixing member in a state where the toner is not coupled. As described above, in this embodiment, the toner enters the contact fixing member in a state where the toners are sufficiently coupled, which is advantageous in terms of fixing strength. Also, the carrier liquid concentration on the surface of the transfer material is lower in this embodiment, which can be said to be advantageous from the viewpoint of the adhesive force between the toner and the transfer material.

  As described above, in this embodiment, the action of the pressure applying member is different from that of the prior art, and the carrier liquid is not adsorbed and removed, but the carrier liquid present in the toner and on the surface of the transfer material is removed by the pressure. Disperse in the direction. In this embodiment, the pressure of the pressure applying member is set to a state suitable for this purpose, the oil repellent member is used on the surface so that the toner does not transfer to the pressure applying member, and the pressure applying member. It is important to keep the surface temperature of the toner below the toner softening point. Further, the present embodiment is characterized in that a non-contact heating unit is provided on the downstream side of the pressure applying member to develop a bond between the toners and an adhesive force between the toner and the transfer material. A sufficient fixing strength is ensured by arranging a contact fixing member on the downstream side.

  As mentioned above, although the specific example was given and demonstrated about embodiment of this invention, this invention is not limited to the content. The present invention can be implemented in various specific forms without departing from the spirit of the present invention.

  The present invention is applicable to a fixing device for a printer, for example.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Paper feeding apparatus 4 Image forming transfer apparatus 41 Photoconductor drum 42 Charging apparatus 43 Exposure apparatus 44 Liquid developing apparatus 45 Intermediate transfer roller 47 Secondary transfer roller 48a Cleaning device 48b for photosensitive drum 48b For intermediate transfer roller Cleaning device 5 Fixing device 5a Fixing device of configuration form 1 5a Fixing device of configuration form 2 50 Roller fixing device (roller fixing device)
51a Fixing roller 51b Pressure roller 52a Heater lamp 52b Heater lamp 60 Non-contact heater (non-contact heating device)
61 Heat insulation cover 62 Heater 80 Pressure applying member 81 Pressure roller 82 Backup roller 90 Preheater X Transfer material

Claims (7)

A fixing device for fixing a toner image developed with a liquid developer containing toner and a carrier liquid to a transfer material,
A pressure applying member that pressurizes the transfer material onto which the toner image has been transferred;
A fixing device, comprising: a non-contact heating device that is provided downstream of the pressure applying member in the transport direction of the transfer material and heats the transfer material in a non-contact manner.   The fixing device according to claim 1, wherein a roller fixing device that heats and pressurizes the transfer material is provided on the downstream side in the transport direction of the transfer material with respect to the non-contact heating device.   The fixing device according to claim 1, further comprising an adjustment mechanism that adjusts a temperature of the pressure applying member to be lower than a predetermined temperature determined according to the type of the toner.   The fixing device according to claim 3, wherein the predetermined temperature is a temperature defined by a softening point of the toner as measured by DSC. A pre-heating device that heats the transfer material in a non-contact manner is provided on the upstream side of the pressure applying member in the conveyance direction of the transfer material,
The fixing device according to claim 3, wherein the adjustment mechanism performs the adjustment by cooling the pressure applying member.   The fixing device according to claim 1, wherein a surface of the pressure applying member is made of an oil repellent material having a contact angle of the carrier liquid of 40 ° or more.   The fixing device according to claim 1, wherein the pressure applying member pressurizes the transfer material at 200 to 3000 kPa.