JP2009234219A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an image forming apparatus capable of enhancing an image quality without requiring any process for modifying surface quality and the like of a target medium body such as an intermediate transfer body or a recording medium and being excellent in ink cohesion and cleaning properties. <P>SOLUTION: The image forming method for the image forming apparatus includes a processing liquid feeding step for feeding a processing liquid to a target medium body and an ink feeding step for adding ink to the processing liquid fed to the target medium body. The processing liquid has a viscosity characteristic with the viscosity increasing with the lapse of the time after the preparation of the processing liquid and is also characterized in that the viscosity during feeding to the target medium body is higher than the viscosity during the preparation of the liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method and an image forming apparatus, and more particularly to an image forming method for forming an image using a processing liquid having a time dependency on viscosity characteristics with respect to temperature.

  Patent Document 1 discloses that an intermediate transfer body having a surface made of a fluorine compound or a silicone compound that is easily repelled even when a liquid such as ink is attached is subjected to surface modification by plasma treatment and addition of a surface active agent, thereby providing ink or the like. A technique for forming a good image without causing bleaching or beating by making it difficult to be repelled even if this liquid adheres is disclosed.

  In Patent Document 2, a surfactant having an HLB (hydrophilic-lipophilic balance) value of 2 to 15 is applied onto an intermediate transfer medium having an elastic layer made of a material such as a rubber material that easily peels off an ink image. , A technique for forming an image on a coated surface to which a surfactant has been applied, heat-viscosizing the ink image, and then transferring the image to a recording medium to achieve good image formation and efficient transfer is disclosed. ing.

  In Patent Document 3, the elastic layer of the transfer drum is formed of silicon rubber or the like having the maximum surface roughness Rmax = 1 to 25 μm, thereby improving the repellency phenomenon of ink applied to the transfer drum. A technique for ensuring the safety is disclosed.

  In Patent Document 4, a hydrophilic portion and a fine water-repellent portion are provided on an intermediate transfer member, ink droplets are applied to the hydrophilic portion, and the ink droplet moves on the intermediate transfer member due to the presence of the fine water-repellent portion. A technique is disclosed that enables high-definition image formation by forming and temporarily fixing an ink image while suppressing the above, and transferring the ink image to a recording medium.

Patent Document 5 discloses a technique for modifying the surface of an intermediate transfer member having a releasability composed of a surface of fluorine rubber or silicon rubber by plasma treatment such as corona treatment and application of an ink viscosity increasing component. Has been.
JP 2005-14255 A JP-A-7-89067 Japanese Patent Laid-Open No. 7-17030 JP 2004-50449 A JP 2005-14256 A

  However, in the invention disclosed in Patent Document 1, the process of modifying the surface of the intermediate transfer member, such as plasma treatment or addition of a surfactant, is complicated, and the apparatus tends to increase in size, increase in cost, and decrease in reliability. .

  The invention disclosed in Patent Document 2 applies a general surfactant to the surface of an intermediate transfer medium of a low surface energy base material having a surface of an elastic layer made of a material such as a rubber material that easily peels an ink image. However, since the surfactant is liable to cause repelling, it is difficult to control the spreading of the ink and it is difficult to form a high-definition image. In addition, heating alone is likely to cause a decrease in transferability due to insufficient aggregation.

  In the invention disclosed in Patent Document 3, wettability is improved if relatively large irregularities are imparted to an elastic body, but high-definition image formation is difficult because ink spreading control is difficult. Further, the transfer residue easily enters the recess, so that cleaning is difficult, and the surface roughness is likely to change due to surface wear due to operation.

  The invention disclosed in Patent Document 4 uses an excimer laser or a diamond die to form a fine water-repellent portion to modify the surface of the intermediate transfer member. However, since the construction method is complicated, it tends to be expensive and yield is high. It is difficult to secure. Further, the fine water-repellent part is easily worn by cleaning or transfer, and durability is also an issue.

  In the invention disclosed in Patent Document 5, the process of modifying the surface of the intermediate transfer member by plasma treatment or the addition of a surfactant is complicated, resulting in an increase in the size of the apparatus, an increase in cost, and a decrease in reliability. Cheap.

  As described above, an intermediate transfer method using an intermediate transfer body having a liquid-repellent elastic body such as fluorine rubber or silicon rubber on the surface has been conventionally used for the purpose of forming good images on various media using inkjet. Although it has been proposed, in order to transfer a high-definition image with high efficiency, the process tends to be complicated, such as surface modification of the intermediate transfer member, leading to an increase in size and cost of the apparatus.

  It is also possible to adjust the viscosity by adding a high-viscosity component such as glycerin to the coating solution for the purpose of improving the coating property of the coating solution with a roller to an intermediate transfer member having a liquid-repellent elastic body on the surface. Although it is possible, ink is ejected onto the coating liquid layer having a high viscosity, and the high-speed processing is difficult due to a delay in ink aggregation and liquid diffusion. Also, high-boiling solvents such as glycerin are difficult to evaporate and dry, so the load of removing the solvent increases, and the colorant fixability in the solid acid method that applies a treatment liquid containing an ink flocculant to the coated medium before ink droplet ejection The quality is liable to deteriorate, such as a decrease in the amount of solvent permeation and an increase in solvent permeation curl in a direct drawing method in which direct drawing is performed on a recording medium.

  The present invention has been made in view of such circumstances, and eliminates the need for a process such as surface modification of an intermediate transfer body to which a liquid such as a processing liquid is applied or a medium to be applied such as a recording medium, and improves image quality. An object of the present invention is to provide an image forming method and an image forming apparatus which can be improved and have good ink aggregating properties, cleaning properties and liquid preparation properties.

  In order to achieve the above object, the present invention includes a treatment liquid application step for applying a treatment liquid to an applied medium, and an ink application step for applying ink to the treatment liquid applied to the application medium. In the image forming method, the processing liquid has a viscosity characteristic that the viscosity after preparation increases with time, and the viscosity when applied to the application medium is higher than the viscosity during preparation, It is characterized by.

  According to the present invention, since the treatment liquid has a viscosity characteristic that the viscosity after preparation increases with time, the viscosity is low and the workability is good at the time of preparation. Can be applied stably to the medium to be applied by controlling to an appropriate viscosity, the workability at the time of liquid preparation is good, and the process such as surface modification of the medium to be applied is unnecessary, improving the quality of the image Can be planned.

  The processing liquid includes a liquid that does not have a function of aggregating ink droplets.

  As one aspect of the present invention, the treatment liquid has a viscosity characteristic that the ratio of the viscosity change amount to the temperature change amount at a predetermined temperature or less is smaller when the temperature is lowered than when the temperature is raised. And

  According to this aspect, since the treatment liquid has a viscosity characteristic that the ratio of the viscosity change amount to the temperature change amount at a predetermined temperature or less is smaller when the temperature is lowered than when the temperature is raised, the treatment liquid is once heated. In this case, the liquid is stable in a low viscosity state, the processing liquid can be controlled to an appropriate viscosity in the processing liquid application process and the ink application process during image formation, and heating of the processing liquid can be simplified.

  As one aspect of the present invention, the treatment liquid contains 1% by weight or more and 10% by weight or less of a surfactant, has a viscosity of less than 15 mPa · s at the time of liquid preparation, and is applied to the application medium. When the temperature is 15 ° C. or more and 40 ° C. or less, the viscosity is 15 mPa · s or more and 60 mPa · s or less, and when the temperature is 60 ° C. or more and 15 ° C. or more and 40 ° C. or less, the viscosity is 15 mPa · s. It is less than s.

  According to this aspect, since the viscosity of the treatment liquid is less than 15 mPa · s at the time of preparation of the treatment liquid, workability such as filtration is good.

  In addition, since the viscosity of the processing liquid is 15 mPa · s or more and 60 mPa · s or less when the temperature is set to 15 ° C. or more and 40 ° C. or less before being applied to the medium to be applied, The processing liquid can be controlled to an appropriate viscosity, and the quality of the image can be improved while eliminating the step of modifying the surface of the medium to be applied.

  In addition, since the viscosity when the temperature is set to 15 ° C. or more and 40 ° C. or less after the temperature is set to 60 ° C. or higher is less than 15 mPa · s, it is possible to control the treatment liquid to an appropriate viscosity in the ink application process during image formation. Image quality can be improved.

  As one aspect of the present invention, in the treatment liquid application step, the treatment liquid before being applied to the application medium is raised to a temperature in the range of 30 ° C. or more and 40 ° C. or less, and then the temperature is reduced to the temperature or less. It is characterized by being applied to an application medium.

  According to this aspect, when applying the treatment liquid to the medium to be applied, the temperature of the treatment liquid can be once increased and then lowered to stabilize it at an appropriate viscosity, and the treatment liquid can be more reliably applied to the medium to be applied. It can be stably applied. Further, the evaporation of moisture in the treatment liquid can be suppressed as compared with a state in which the treatment liquid is always heated to a heating temperature of 30 ° C. or more and 40 ° C. or less. In the case of raising the temperature inside the apparatus, it is effective to adjust the temperature of the treatment liquid after heating to the heating temperature to 20 ° C. or higher and 30 ° C. or lower.

  As an aspect of the present invention, the ink application step is characterized in that ink is applied to the treatment liquid that has been heated to 10 ° C. or higher and 50 ° C. or lower after the temperature is raised above 50 ° C.

  According to this aspect, in the ink application process, the ink is applied to the treatment liquid that has been raised from 10 ° C. to 50 ° C. after the temperature is raised above 50 ° C., so that the treatment liquid on the medium to be applied is reduced in viscosity. Ink aggregation is accelerated. In addition, even when a liquid that does not have a function of aggregating ink droplets is used as the treatment liquid, it is possible to ensure the ink droplet spreading rate. Further, since the temperature before ink application is low, it is possible to prevent drying of the ink application part (nozzle, etc.) of the ink application means and to stabilize the ejection operation.

  As one aspect of the present invention, the surfactant is a fluorine-based anionic surfactant represented by the following chemical formula 1.

  According to this aspect, the viscosity characteristic with respect to the temperature of the processing liquid can be time-dependent. For example, for the processing liquid, the ratio of the viscosity change amount to the temperature change amount is lower than when the temperature is increased. The viscosity can be made smaller and the viscosity after preparation can be given a viscosity characteristic that increases with time.

  As one embodiment of the present invention, the treatment liquid contains polymer particles or microcapsules having a particle size of 0.5 μm or more and 5 μm or less.

  According to this aspect, the treatment liquid can be stably applied to the medium to be applied, the fixing property of the ink coloring material is improved, and the transferability and fixing property of the image are improved.

  As one aspect of the present invention, the polymer particles are polyethylene.

  According to this aspect, polyethylene has appropriate adhesion, and for example, the cleaning property of the intermediate transfer member is improved.

  As one embodiment of the present invention, the microcapsules are characterized in that a higher alcohol or ester is included in a polyvinyl alcohol film agent.

  According to such an embodiment, the storage stability of the treatment liquid can be ensured, and the transferability and fixability are improved.

  As one aspect of the present invention, the treatment liquid application step is characterized in that the treatment liquid is applied to the application medium with a thickness of 1 μm or more and 15 μm or less.

  As an aspect of the present invention, the applied medium is an intermediate transfer member in an intermediate transfer type image forming apparatus.

  As an aspect of the present invention, the surface energy of the intermediate transfer member is 15 mN / m or more and 30 mN / m or less.

  As one embodiment of the present invention, the treatment liquid contains 5% by weight or more and 20% by weight or less of an ink flocculant.

  As one aspect of the present invention, the treatment liquid does not contain an ink flocculant, and has a flocculant application step of applying an ink flocculant to the ink applied in the ink application step. To do.

  As one aspect of the present invention, the imparted medium is a recording medium in a direct drawing type image forming apparatus.

  In order to achieve the above object, the present invention includes a treatment liquid application unit that applies a treatment liquid to an application medium, and an ink application unit that applies ink to the treatment liquid applied to the application medium. In the image forming apparatus, the processing liquid has a viscosity characteristic that the viscosity after preparation increases with time, and the viscosity when applied to the application medium is higher than the viscosity during preparation. A temperature adjusting means for adjusting the temperature of the processing liquid; and when the processing liquid is applied to the medium to be applied by the processing liquid applying means, the temperature of the processing liquid is adjusted by the temperature adjusting means. And a control means for controlling the viscosity of the liquid.

  According to the present invention, it is possible to improve the quality of an image while eliminating the step of modifying the surface of a medium to be applied such as an intermediate transfer body or a recording medium to which a liquid such as a processing liquid is applied. And cleaning properties are also improved.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, application to an inkjet recording apparatus will be described as an example.

[Overall Configuration of Inkjet Recording Apparatus According to First Embodiment]
First, an ink jet recording apparatus which is an embodiment of an image forming apparatus according to the present invention will be described. FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to the first embodiment. As shown in FIG. 1, the ink jet recording apparatus 10 of the present embodiment records an image (primary image) on an intermediate transfer body 12 that is a permeation medium, and then transfers the image onto a recording medium 14 such as plain paper. This is a recording apparatus to which a transfer method for forming an image (secondary image) is applied. As a main component, an aggregation treatment agent (hereinafter referred to simply as “treatment liquid” in this embodiment) is applied to the intermediate transfer body 12. A treatment liquid application unit 16 (which corresponds to a part to which the “liquid application apparatus” according to the present invention is applied) for applying and a treatment liquid applied on the intermediate transfer body 12 is dried and cooled. A heating unit 18 and a cooler 20, a printing unit 22 that applies inks of a plurality of colors to the intermediate transfer body 12, and a solvent removal unit that removes the liquid solvent (excess solvent) on the intermediate transfer body 12 after ink ejection. 24 and shape on the intermediate transfer body 12 A transfer unit 26 that transfers the ink image to the recording medium 14, a paper supply unit 28 that supplies the recording medium 14 to the transfer unit 26, and a cleaning unit that cleans the intermediate transfer body 12 after the transfer ( The first cleaning unit 30 and the second cleaning unit 32) are provided.

  The composition of the treatment liquid and ink used in this example will be described in detail later, but the treatment liquid is an acidic liquid having an action of aggregating the coloring material contained in the ink. The ink is a colored ink containing a coloring material (pigment) of each color of yellow (Y), magenta (M), cyan (C), and black (K).

  An endless belt is applied to the intermediate transfer member 12. This intermediate transfer member (endless belt) 12 is wound around a plurality of rollers (three stretching rollers 34A to 34C and transfer roller 36 are shown in FIG. 1, but the belt winding form is not limited to this example). When the power of a motor (not shown in FIG. 1 and shown as reference numeral 288 in FIG. 24) is transmitted to at least one of the stretching rollers 34A to 34C and the transfer roller 36, an intermediate transfer member 12 is driven in the counterclockwise direction (direction indicated by arrow A) in FIG. A tension roller indicated by reference numeral 34C is a tensioner member that performs meandering correction and tension application of the belt.

  The intermediate transfer body 12 has a non-penetrable ink droplet of resin, metal, rubber, etc. in an image forming area (not shown) on which at least a primary image is formed on a surface (image forming surface) 12A facing the printing unit 22. It has permeability. Further, at least the image forming area of the intermediate transfer body 12 is configured to form a smooth surface having a predetermined flatness.

  Preferred materials used for the surface layer including the image forming surface 12A of the intermediate transfer body 12 include, for example, a polyimide resin, a silicon resin, a polyurethane resin, a polyester resin, a polystyrene resin, a polyolefin resin, and a polybutadiene resin. And publicly known materials such as polyamide resins, polyvinyl chloride resins, polyethylene resins, and fluorine resins.

  Further, it is preferable that the surface tension of the surface layer of the intermediate transfer body 12 is 10 mN / m or more and 40 mN / m or less. When the surface tension of the surface layer of the intermediate transfer body 12 is 40 mN / m or more, the difference in surface tension from the recording medium 14 onto which the primary image is transferred is eliminated (or extremely small), and the transferability of the ink aggregate is deteriorated. To do. Further, when the surface tension of the surface layer of the intermediate transfer body 12 is 10 mN / m or less, the surface tension of the processing liquid is more than the surface tension of the surface layer of the intermediate transfer body 12 in consideration of the wettability of the processing liquid. Therefore, it is difficult to make the surface tension of the processing liquid 10 mN / m or less, and the design freedom (selection range) of the intermediate transfer body 12 and the processing liquid is narrowed.

As the intermediate transfer body 12 in the present embodiment, an elastic material having a surface energy of about 15 to 30 mN / m (= mJ / m ² ) is applied to a base material such as polyimide from the viewpoint of durability and transferability of plain paper to about 30 to 150 μm. A coating with a thickness of is desirable, and coatings such as urethane rubber, silicone rubber, fluororubber, and fluoroelastomer are suitable.

  The treatment liquid application unit 16 applies a treatment liquid (aggregation treatment agent) as an undercoat liquid to the intermediate transfer body 12 after the cleaning process by the first cleaning unit 30 described later, and is more intermediate than the printing unit 22. Arranged upstream in the transport direction. Although the detailed structure of the liquid application apparatus applied to the treatment liquid application unit 16 will be described later, the application of the treatment liquid to the intermediate transfer body 12 is selectively applied to the image forming unit by reverse coating of the gravure roller 38 or the spiral roller. Is desirable.

  That is, the processing liquid application unit 16 of this example includes a gravure roller (“corresponding to a roller member”) 38 as an application roller and a processing liquid container 40. By rotating the gravure roller 38 in the direction opposite to the conveying direction of the intermediate transfer body 12 while the gravure roller 38 to which the processing liquid is adhered is in contact with the intermediate transfer body 12, the processing liquid is transferred to the image forming surface of the intermediate transfer body 12. It is applied to 12A. Although details will be described later, in the maintenance cleaning of the intermediate transfer body 12, the gravure roller 38 is used as a wiping means.

  In addition, the treatment liquid has a polymer resin (fine particle) of 1 wt% to 5 wt% for the purpose of further stabilizing coating unevenness, improving the agglomerate fixability when ink is deposited, and improving the releasability during transfer. The aspect which contains is preferable. It is preferable to add a microcapsule containing higher alcohols or esters in addition to the polymer resin, because it is destroyed by heat and pressure during transfer and the releasability is further improved. Although details will be described later, in the maintenance cleaning of the intermediate transfer body 12, a cleaning surfactant or abrasive particles may be included in the cleaning liquid.

  A heating unit 18 is disposed on the downstream side of the treatment liquid application unit 16 and on the upstream side of the printing unit 22. As the heating unit 18 in this example, a heater whose temperature is controlled in a range of 50 ° C. or more and 100 ° C. or less is used. The treatment liquid applied onto the intermediate transfer body 12 by the treatment liquid application unit 16 is heated by passing through the heating unit 18, and the solvent component is evaporated and dried. As a result, an aggregation treatment agent layer (thin film layer from which the treatment liquid has been dried) having a thickness of 0.5 μm or more and 3 μm or less is formed on the surface of the intermediate transfer body 12.

  A cooler 20 is disposed on the downstream side of the heating unit 18 in the conveyance direction of the intermediate transfer body and on the upstream side of the printing unit 22. The cooler 20 is disposed on the back side of the intermediate transfer body 12. The cooler 20 can be controlled within a predetermined temperature range. In the present embodiment, for example, the cooler 20 is controlled to be 35 ° C. or higher and 45 ° C. or lower. By reducing the temperature of the intermediate transfer body 12 on which the aggregation treatment agent layer has been formed by heat drying of the heating unit 18 to 35 ° C. or higher and 45 ° C. or lower with the cooler 20, the radiant heat from the intermediate transfer body 12 is reduced, The drying of the ink in the nozzles of the head in the printing unit 22 is suppressed, and the ejection characteristics are stabilized.

  The print unit 22 arranged at the rear stage of the cooler 20 is an ink jet type liquid discharge head (hereinafter referred to as “head”) corresponding to each ink color of yellow (Y), magenta (M), cyan (C), and black (K). ] 22Y, 22M, 22C, 22K.

  Aggregation is performed by discharging pigment inks of each color (CMYK) from the heads 22Y, 22M, 22C, and 22K of the printing unit 22 to the aggregation treatment agent layer on the intermediate transfer body 12 that has passed through the cooler 20 in accordance with image signals. Dropping is performed on the treatment agent layer. In the case of this example, the ink discharge volume by each of the heads 22Y, 22M, 22C, and 22K is about 2 pl, and the recording density is the main scanning direction (width direction of the intermediate transfer body 12) and the sub-scanning direction (conveyance of the intermediate transfer body 12). Both directions are recorded at 1200 dpi. The ink may contain a polymer resin (fine particles) having film-forming properties. In such an embodiment, the abrasion resistance and storage stability are improved by the transfer process and the fixing process.

  When ink droplets are landed on the aggregating agent layer, the contact surface between the ink and the aggregating agent layer lands on a predetermined area due to the balance between the flying energy and the surface energy. The aggregation reaction starts immediately after the ink has landed on the aggregation treatment agent, but the aggregation reaction starts from the contact surface between the ink and the aggregation treatment agent layer. The agglomeration reaction occurs only in the vicinity of the contact surface, and the color material in the ink is agglomerated in a state where the adhesive force is obtained with a predetermined contact area at the time of ink landing, so that the color material movement is suppressed.

  Even if other ink droplets land adjacent to this ink droplet, the color material of the ink that has landed first is already agglomerated, so the color materials do not mix with the ink that landed later, Bleed is suppressed. After the color material is aggregated, the separated ink solvent spreads, and a liquid layer in which the aggregation treatment agent is dissolved is formed on the intermediate transfer body 12.

  As described above, the ink that has landed on the aggregation treatment agent layer forms an aggregate of pigment by an aggregation reaction and is separated from the solvent. The solvent (residual solvent) component separated from the pigment aggregate is removed from the intermediate transfer member 12 by the solvent removal roller 42 of the solvent removal unit 24 arranged at the subsequent stage of the printing unit 22.

  The solvent removal roller 42 used here is preferably one that traps liquid in a cell on the outer peripheral surface having the same shape as the gravure roller 38 for application, or one that traps liquid in a groove on the outer peripheral surface. The liquid captured by the solvent removal roller 42 is removed from the solvent removal roller 42 by air injection or liquid injection.

  In this manner, in the aspect in which the solvent on the image forming surface 12A of the intermediate transfer body 12 is removed by the solvent removal roller 42, the solvent on the intermediate transfer body 12 is suitably removed, and therefore the transfer unit 26 applies the recording medium 14 to the recording medium 14. A large amount of solvent (dispersion medium) is not transferred. Therefore, even when paper such as plain paper is used as the recording medium 14, problems characteristic to aqueous solvents such as curls and cockles can be prevented.

  Further, by removing excess solvent from the ink aggregate by the solvent removing unit 24, the ink aggregate can be concentrated and the internal aggregating force can be further increased. As a result, the fusion of the resin particles contained in the ink aggregate is effectively promoted, and a stronger internal cohesive force can be imparted to the ink aggregate up to the transfer step by the transfer unit 26. Further, the effective concentration of the ink aggregates by removing the solvent can impart good fixability and gloss to the image even after the image is transferred to the recording medium 14.

  It is not always necessary to remove all the solvent on the intermediate transfer body 12 by the solvent removing unit 24. If the ink aggregate is excessively removed by excessively removing the ink aggregate, the adhesion of the ink aggregate to the transfer body becomes too strong, and an excessive pressure is required for the transfer. Rather, in order to maintain viscoelasticity suitable for transferability, it is preferable to leave a small amount.

  The effects obtained by leaving a small amount of the solvent on the intermediate transfer member 12 include the following. That is, since ink aggregates are hydrophobic and solvent components that are difficult to volatilize (mainly organic solvents such as glycerin) are hydrophilic, ink aggregates and residual solvent components are separated after solvent removal, and residual solvent components A thin liquid layer is formed between the ink aggregate and the intermediate transfer member. Therefore, the adhesive force of the ink aggregate to the intermediate transfer body 12 becomes weak, which is advantageous for improving transferability.

  If a treatment liquid such as treatment liquid T-2 described later is used, the aggregation treatment agent layer is dried by heating in the heating unit 18 to reduce the viscosity, and then immediately after cooling with the cooler 20, the aggregation The treatment agent layer is maintained in a low viscosity state. Therefore, the ink aggregation reaction is promoted when the pigment ink of each color (YMCK) is ejected from the heads 22Y, 22M, 22C, and 22K of the printing unit 22 and ejected onto the aggregation treatment agent layer. Therefore, high-speed processing of solvent removal in the solvent removal unit 24 is possible.

  Note that the amount of ink ejected onto the intermediate transfer body 12 varies depending on the image content. Therefore, for an image with a large amount of white background (an image with a small amount of ink), mist ejection from the mist ejection nozzle 43 is performed to compensate for the amount of ink. Thus, the amount of water on the intermediate transfer body 12 is stabilized within a predetermined allowable range.

  A dirt detector 44 for detecting dirt on the intermediate transfer body 12 and a preheater 46 as a preheating means are arranged downstream of the solvent removing section 24 in the conveyance direction of the intermediate transfer body and in front of the transfer section 26. Yes. The preheater 46 of this example is disposed on the back surface 12B side of the intermediate transfer body 12, and is configured to heat the intermediate transfer body 12 on which the primary image is formed from the back surface 12B side.

  The heating temperature range of the preheater 46 is 90 ° C. or more and 130 ° C. or less, and is set to a heating temperature (90 ° C. in this example) or more at the time of transfer in the transfer portion 26. The image forming area of the intermediate transfer body 12 is preheated, and then the transferred image is transferred from the intermediate transfer body 12 onto the recording medium 14 by the transfer section 26, so that the transfer section 26 is compared with the case where no preheating is performed. The heating temperature can be set low, and the transfer time of the transfer section 26 can be shortened.

  The transfer unit 26 includes a transfer roller 36 having a heater (not shown in FIG. 1, representative of a plurality of heaters shown in FIG. 24 and indicated by reference numeral 289), and a heating and pressure nip disposed opposite thereto. And a pressure roller 48. The intermediate transfer body 12 and the recording medium 14 are sandwiched between the transfer roller 36 and the pressure roller 48, and are heated to a predetermined temperature while being pressurized at a predetermined pressure (nip pressure), whereby the intermediate transfer body 12 is heated. The primary image formed on the recording medium 14 is transferred to the recording medium 14.

  As a means for adjusting the nip pressure at the time of transfer in the transfer section 26, for example, a mechanism (drive means) for moving the transfer roller 36, the pressure roller 48, or both in the vertical direction of FIG.

  A preferable nip pressure at the time of transfer is 1.0 to 2.0 MPa, and a preferable heating temperature (roller temperature) is 80 to 120 ° C. In this example, both the transfer roller 36 and the pressure roller 48 are set to 90 ° C. If the heating temperature at the time of transfer roller transfer is too high, there is a problem such as deformation of the intermediate transfer body 12. On the other hand, if the heating temperature is too low, the transferability is deteriorated.

  In addition, it is preferable that the recording medium 14 is preliminarily (pre) heated to 70 to 100 ° C. by the paper feeding unit 28 before transfer, so that transferability is further improved. In the case of this example, a heater 50 is provided in the paper feeding unit 28 as a preheating means for the recording medium 14. The recording medium 14 preliminarily heated by the heater 50 is nipped and fed to the transfer unit 26 by a paper feed roller composed of a pair of adhesive rollers 52 and 53.

  If polymer particles or microcapsules are added to the treatment liquid applied to the intermediate transfer body 12 in the treatment liquid application section 16, the releasability is achieved by the action of the polymer particles and microcapsules remaining on the intermediate transfer body 12. And the effect of further improving the transferability in the transfer portion 26 is obtained. Further, since nuclei are imparted on the intermediate transfer body 12, the repellency of the processing liquid is further reduced even with the low surface energy intermediate transfer body 12, and the coating stability is further improved.

  As a configuration of the paper supply unit 28, a mode in which a magazine for rolled paper (continuous paper) is provided, or instead of or in combination with a magazine for rolled paper, paper is supplied by a cassette in which cut sheets are stacked and loaded. There is a mode to do. In the case of an apparatus configuration using roll paper, a cutter for cutting is provided, and the roll paper is cut into a desired size by the cutter. A plurality of magazines and cassettes having different paper widths and paper qualities may be provided.

  When a plurality of types of recording media can be used, an information recording body such as a barcode or a wireless tag that records the media type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Thus, it is preferable to automatically determine the type of recording medium (media type) to be used and perform ink ejection control so as to realize appropriate ink ejection according to the media type.

  Specific examples of the recording medium 14 applied to this example include permeable media such as plain paper (including high-quality paper and recycled paper), ink-jet exclusive paper, and non-permeable or low-permeable media such as coated paper. There are various media such as sealing paper with an adhesive and a release label on the back, resin films such as OHP sheets, metal sheets, cloth, and wood.

  The recording medium 14 sent to the transfer unit 26 is heated and pressed at a predetermined temperature and a predetermined nip pressure by the transfer roller 36 and the pressure roller 48, and the primary image on the intermediate transfer body 12 is transferred onto the recording medium 14. Is done. The recording medium 14 (printed material) that has passed through the transfer section 26 is separated from the intermediate transfer body 12 by the peeling claw 56 and is discharged out of the apparatus by a conveying means (not shown). Although not shown in FIG. 1, the paper output unit is provided with a sorter for collecting printed products according to print orders.

  The recording medium 14 (printed material) peeled off from the intermediate transfer body 12 may be subjected to a fixing process (not shown) before being discharged outside the apparatus. The fixing unit includes, for example, a heating roller pair whose temperature and pressure can be adjusted. By adding such a fixing step, the polymer fine particles contained in the ink are formed (a thin film in which the polymer fine particles are dissolved is formed on the outermost surface of the image), thereby further improving the abrasion resistance and storage property. improves. The heating temperature in the fixing step is preferably 80 ° C. or higher and 130 ° C. or lower, and the applied pressure is preferably 1.0 to 3.0 MPa, and is optimized according to the temperature characteristics (film formation temperature: MFT) of the added polymer resin. Of course, in the transfer process in the transfer unit 26, if both transferability and film formation can be achieved, a mode in which the fixing unit is omitted is possible.

  After the transfer process by the transfer unit 26, the intermediate transfer body 12 that has passed through the peeling unit by the peeling claw 56 reaches the first cleaning unit 30.

  The first cleaning unit 30 cleans the intermediate transfer body 12 using water such as distilled water or purified water, a solvent recovered by the solvent removal unit 24, or a cleaning liquid obtained by adding a sea surface active agent to these liquids. The cleaning liquid ejecting unit 60 that ejects the cleaning liquid, the rotating brush 62 that is brought into contact with the image forming surface 12A of the intermediate transfer body 12 and rotates reversely with respect to the conveyance direction of the intermediate transfer body, and the surface of the intermediate transfer body 12 are wiped by sliding. The blade 64 is configured. A heater 65 is disposed on the back surface side of the intermediate transfer body 12 in the first cleaning unit 30. The first cleaning unit 30 mainly functions as a means for cleaning the intermediate transfer body 12 after the image transfer to the recording medium 14 is completed.

  Further, when a surfactant is included in the processing liquid applied to the intermediate transfer body 12 in the processing liquid application unit 16, the cleaning liquid is reduced in viscosity by the action of the surfactant remaining on the intermediate transfer body 12. Since the surface tension is reduced, the cleaning is performed at high speed and reliably.

  The liquid cleaning process using the cleaning liquid performed in the first cleaning unit 30 is suitable for high-speed continuous processing, but a slight residue is likely to remain on the intermediate transfer body 12, and the edge portion of the intermediate transfer body 12 is stably cleaned. There is a limit. For this reason, the accumulation of residues due to long-term operation may cause problems such as transferability and texture deterioration, device contamination and malfunction.

  Alternatively, when hard dust such as sand dust adheres to the intermediate transfer member due to taking in outside air for cooling inside the machine, generating dust inside the machine, maintenance work, etc., a wiping member (rotating brush 62 or And the intermediate transfer body 12 may be damaged such as a scratch.

  From the viewpoint of coping with such a problem, the present embodiment includes a second cleaning unit 32 that uses an adhesive member (adhesive rollers 66 and 68 for removing dust). The second cleaning unit 32 includes adhesive rollers 66 and 68 capable of controlling movement of contact and separation with respect to the surface (12A) of the intermediate transfer body 12, and a cleaning web (or adhesive) that can be in contact with the adhesive rollers 66 and 68. Belt) 70. As shown in the figure, the second cleaning unit 32 is disposed at a position facing the stretching roller 34A.

  The adhesive rollers 66 and 68 are brought into contact with the intermediate transfer body 12 and rotated during non-image formation such as when the ink jet recording apparatus is started up, during standby, during batch processing, or before liquid cleaning during image formation. As a result, foreign matter on the intermediate transfer member 12 is attached to the adhesive rollers 66 and 68, foreign matter (dust) is removed from the intermediate transfer member, and the surface of the intermediate transfer member is cleaned.

  The foreign matter adhering to the surfaces of the adhesive rollers 66 and 68 is rotated by bringing the adhesive rollers 66 and 68 into contact with the cleaning web (or adhesive belt) 70 when the adhesive rollers 66 and 68 are separated from the intermediate transfer body 12. Thus, the foreign matter on the adhesive rollers 66 and 68 can be moved to the cleaning web (or adhesive belt) 70. As a result, the surfaces of the adhesive rollers 66 and 68 can be cleaned.

Next, the configuration of the main part of the inkjet recording apparatus 10 will be further described in detail.
(Composition of printing part)
As shown in FIG. 1, the printing unit 22 corresponds to each color in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side in the intermediate transfer member conveyance direction. The heads 22Y, 22M, 22C, and 22K are arranged side by side.

  The ink storage / loading unit 74 includes ink tanks that store ink liquids respectively supplied to the heads 22Y, 22M, 22C, and 22K. Each ink tank communicates with a corresponding head through a required flow path, and supplies a corresponding ink liquid to each head. The ink storage / loading unit 74 includes notifying means (display means, warning sound generating means) for notifying when the remaining amount of liquid in the tank is low, and has a mechanism for preventing erroneous loading between liquids. is doing.

  Ink is supplied from each ink tank of the ink storage / loading unit 74 to each head 22Y, 22M, 22C, 22K, and corresponds to the image forming surface 12A of the intermediate transfer body 12 from each head 22Y, 22M, 22C, 22K. Color ink to be ejected.

  FIG. 2 is a plan view of the printing unit 22. As shown in the figure, each of the heads 22Y, 22M, 22C, and 22K has a length corresponding to the maximum width of the image forming area in the intermediate transfer body 12, and the entire width of the image forming area is formed on the ink discharge surface thereof. This is a full-line type head having a nozzle row in which a plurality of nozzles for ink ejection (not shown in FIG. 1 and indicated by reference numeral 81 in FIG. 3) are arranged. Each of the heads 22Y, 22M, 22C, and 22K is fixedly installed so as to extend in a direction orthogonal to the intermediate transfer member conveyance direction.

  According to the configuration in which the full line type head having the nozzle row covering the entire width of the intermediate transfer body 12 is provided for each discharge liquid, the intermediate transfer body 12 and the printing are performed in the transport direction (sub-scanning direction) of the intermediate transfer body 12. An image (primary image) can be formed in the image forming area of the intermediate transfer body 12 by performing the operation of relatively moving the portion 22 once (that is, by one sub-scan). As a result, high-speed printing is possible compared to the case where a serial (shuttle) type head that reciprocates in the direction perpendicular to the intermediate transfer member conveyance direction (main scanning direction; see FIG. 2) is applied. Can be improved.

  In this example, the configuration of CMYK standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add an ink head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

[Head structure]
Next, the structure of each head will be described. Since the structures of the color-specific heads 22Y, 22M, 22C, and 22K are common, the heads are represented by reference numeral 80 in the following.

  3A is a plan perspective view showing an example of the structure of the head 80, and FIG. 3B is an enlarged view of a part thereof. In order to increase the dot pitch printed on the recording medium 14, it is necessary to increase the nozzle pitch in the head 80. As shown in FIGS. 3A and 3B, the head 80 of this example includes a plurality of ink chamber units (recording) including nozzles 81 serving as ink discharge ports, pressure chambers 82 corresponding to the nozzles 81, and the like. It has a structure in which droplet discharge elements 83 as element units are arranged in a zigzag matrix (two-dimensionally), so that in the longitudinal direction of the head (direction perpendicular to the conveyance direction of the intermediate transfer body 12). A high density of substantial nozzle intervals (projection nozzle pitch) projected so as to be aligned along the line is achieved.

  One or more nozzle rows are arranged over a length corresponding to the entire width of the image forming area of the intermediate transfer body 12 in a direction (arrow M in FIG. 3) substantially orthogonal to the conveyance direction of the intermediate transfer body 12 (arrow S in FIG. 3). The form which comprises is not limited to the example of illustration. For example, instead of the configuration of FIG. 3 (a), as shown in FIG. 4, a short head module 80 ′ in which a plurality of nozzles 81 are two-dimensionally arranged is arranged in a staggered manner and connected to each other. Therefore, a line head having a nozzle row having a length corresponding to the entire width of the image forming area of the intermediate transfer body 12 as a whole may be configured.

  The pressure chamber 82 provided corresponding to each nozzle 81 has a substantially square planar shape (see FIGS. 3A and 3B), and the nozzle 81 is provided at one of the diagonal corners. An outlet for supplying ink (supply port) 84 is provided on the other side. Note that the shape of the pressure chamber 82 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon, other polygons, a circle, and an ellipse.

  FIG. 5 is a cross-sectional view showing a three-dimensional configuration of one channel of droplet discharge elements (ink chamber unit corresponding to one nozzle 81) serving as a recording element unit in the head 80 (5- in FIG. 3A). 5 is a sectional view taken along line 5).

  As shown in FIG. 5, each pressure chamber 82 communicates with the common flow path 85 via the supply port 84. The common flow path 85 communicates with an ink tank (not shown in FIG. 5; equivalent to the reference numeral 74 in FIG. 1) as an ink supply source, and the ink supplied from the ink tank passes through the common flow path 85. It is supplied to the pressure chamber 82.

  An actuator 88 having an individual electrode 87 is joined to a pressure plate (vibrating plate also serving as a common electrode) 86 constituting a part of the pressure chamber 82 (the top surface in FIG. 5). By applying a driving voltage between the individual electrode 87 and the common electrode, the actuator 88 is deformed to change the volume of the pressure chamber 82, and ink is ejected from the nozzle 81 due to the pressure change accompanying this. The actuator 88 is preferably a piezoelectric element using a piezoelectric material such as lead zirconate titanate or barium titanate. After the ink is ejected, when the displacement of the actuator 88 returns, the pressure chamber 82 is refilled with new ink from the common channel 85 through the supply port 84.

  By controlling the driving of the actuator 88 corresponding to each nozzle 81 according to the dot data generated by the digital halftoning process from the input image, the ink droplets can be ejected from the nozzle 81. While conveying the intermediate transfer body 12 in the sub-scanning direction at a constant speed, the ink discharge timing of each nozzle 81 is controlled in accordance with the conveyance speed, whereby a desired image (here, transfer image) is transferred onto the intermediate transfer body 12. The previous primary image) can be recorded.

  As shown in FIG. 6, the ink chamber unit 83 having the structure described above is latticed in a fixed arrangement pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape.

  That is, the pitch P of the nozzles projected (orthographically projected) so as to be arranged in the main scanning direction by a structure in which a plurality of ink chamber units 83 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction. D × cos θ, and in the main scanning direction, each nozzle 81 can be handled equivalently as a linear array with a constant pitch P. With such a configuration, it is possible to realize a substantial increase in the density of nozzle rows projected so as to be aligned in the main scanning direction.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzle is divided into blocks, and each block is sequentially driven from one side to the other. The width direction of the intermediate transfer body 12 (the direction orthogonal to the conveyance direction of the intermediate transfer body 12) is performed. ) Is defined as main scanning, which prints one line (a line composed of a single line of dots or a line composed of a plurality of lines of dots).

  In particular, when driving the nozzles 81 arranged in a matrix as shown in FIG. 6, the main scanning as described in the above (3) is preferable. That is, nozzles 81-11, 81-12, 81-13, 81-14, 81-15, 81-16 are made into one block (other nozzles 81-21,..., 81-26 are made into one block, Nozzles 81-31,..., 81-36 as one block,..., And the nozzles 81-11, 81-12,. One line is printed in the width direction of the transfer body 12.

  On the other hand, by moving the full line head and the intermediate transfer body 12 relative to each other, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the main scanning described above is repeated. What is done is defined as sub-scanning.

  The direction indicated by one line (or the longitudinal direction of the belt-like region) recorded by the main scanning is referred to as a main scanning direction, and the direction in which the sub scanning is performed is referred to as a sub scanning direction. In other words, in the present embodiment, the conveyance direction of the intermediate transfer body 12 is the sub-scanning direction, and the direction orthogonal thereto is the main scanning direction. In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example.

  In this embodiment, a method of ejecting ink droplets by deformation of an actuator 88 typified by a piezo element (piezoelectric element) is adopted. However, the method of ejecting ink is not particularly limited in implementing the present invention. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

[Adjustment of coagulation treatment agent]
(Example of treatment liquid 1)
Treatment liquid T-1 was prepared as Example 1 of the treatment liquid with the composition shown in [Table 1]. The physical properties of the treatment liquid T-1 obtained by this adjustment were measured, and as a result, the pH was 3.6, the surface tension was 28.0 mN / m, and the viscosity was 3.1 mPa · s.

(Example of treatment liquid 2)
Furthermore, the treatment liquid T-2 to which a surfactant was added with the composition shown in [Table 2] was prepared. The physical properties of the treatment liquid (Example 2) obtained by this adjustment were measured. As a result, the pH was 3.5, the surface tension was 18.0 mN / m, and the viscosity was 10.1 mPa · s.

  The chemical formula of the fluorosurfactant 1 used in [Table 2] is shown in [Chemical Formula 1].

  Furthermore, when this treatment liquid T-2 was put in a polyethylene container and the viscosity after being allowed to stand at room temperature (20 ° C. or higher and 30 ° C. or lower) for 3 days was examined, the viscosity increased from 10.1 mPa · s to 39.2 mPa · s. In addition, it could be applied to silicone rubber, fluorine rubber, and fluorine-based elastomers (Shin-Etsu Chemical Co., Ltd .: SIFEL600 series, etc.) without causing repelling. As a follow-up test, the temperature-viscosity characteristics were examined. The viscosity decreased by heating, but it increased only to about 10 mPa · s even if it was immediately cooled, and it was measured again after 3 days. It was as high as before heating. It was found to return to viscosity.

  Although the mechanism of this phenomenon has not been fully elucidated, it is considered that the dispersion state after the preparation changes with time and the surfactant is entangled. Further, when the temperature is raised, the entanglement is released and the viscosity is lowered. Even if the temperature is lowered, the entanglement does not occur for a while, but it is presumed that the entanglement progresses with time and the viscosity increases.

  By utilizing this characteristic, it is excellent in material manufacturing suitability such as filterability, it is excellent in application property to the intermediate transfer body 12, and it is reduced in viscosity by heat during the process. In addition, it is possible to realize an intermediate transfer type ink jet recording apparatus excellent in the above-described case.

  In addition, about the composition of process liquid T-2, it is not limited to the specification shown in Table 2, For example, the specification which contains 10 weight% or less of 1 weight% or more of surfactant is also considered.

  In FIG. 7, the figure of the evaluation result about the viscosity characteristic with respect to the temperature of the process liquid T-1 and the process liquid T-2 is shown. In FIG. 7, the evaluation results (lot 1 and lot 2) for the treatment liquid T-2 are shown twice.

  As shown in FIG. 7, the treatment liquid T-1 does not have time dependency with respect to the viscosity characteristic with respect to temperature, and the viscosity characteristic is in a proportional relationship in which the temperature and the viscosity are constant regardless of the passage of time.

  On the other hand, the treatment liquid T-2 has time dependency with respect to the viscosity property with respect to the temperature, and the viscosity property with respect to the temperature changes with the passage of time.

  Specifically, as shown in FIG. 7, the treatment liquid T-2 has a low viscosity at the time of liquid preparation, but the viscosity increases with the passage of time. When the temperature of the processing liquid T-2 is increased after the viscosity has increased, the viscosity decreases, but the viscosity does not increase immediately even when the temperature of the processing liquid T-2 is decreased, and the ratio of the viscosity change amount to the temperature change amount Has a lower viscosity characteristic when the temperature is lowered than when the temperature is raised. And after lowering | hanging temperature, it has the viscosity characteristic which raises gradually with progress of time.

  More specifically, for example, when the treatment liquid T-2 is prepared at a temperature of 20 ° C. or higher and 40 ° C. or lower, the viscosity is less than 15 mPa · s and stable for about 12 hours. The viscosity rapidly increases after 12 hours have passed when the temperature is 20 ° C. or higher and 40 ° C. or lower (arrow (1) in FIG. 7). After the viscosity rises, when the temperature of the treatment liquid T-2 is set to 15 ° C. or more and 40 ° C. or less, the viscosity becomes 15 mPa · s or more and 60 mPa · s or less (arrow (2) in FIG. 7).

  Further, when the temperature of the treatment liquid T-2 is raised from 40 ° C., the viscosity is further lowered (arrow (3) in FIG. 7), and when it is raised to 60 ° C. or more, the viscosity is lowered to 2 to 3 mPa · s.

  However, after that, when the temperature of the treatment liquid T-2 is lowered, at a temperature higher than 40 ° C., the ratio of the viscosity change amount to the temperature change amount is almost the same as when the temperature is raised, and the viscosity increases. The ratio of the viscosity change amount with respect to the temperature change amount is smaller than when the temperature is raised, and the viscosity is less than 15 mPa · s even when the temperature is lowered to 15 ° C. or more and 40 ° C. or less. It rises only to 15 mPa · s to 25 mPa · s (arrow (4) in FIG. 7).

  After that, as described above, the viscosity rises again with time (arrow (1) in FIG. 7).

  As described above, the treatment liquid T-2 has time dependency with respect to the viscosity characteristics with respect to temperature.

  The mechanism of this phenomenon has not been fully elucidated, but is presumed as follows. First, the dispersion state after preparation changes with time, and the surfactant contained in the treatment liquid T-2 is entangled by micelles (aggregation of surfactant). As a result, the treatment liquid T-2 has thixotropy (viscosity time dependence). When the temperature is raised, the entanglement caused by the micelles is released, and the viscosity is lowered. Although no entanglement occurs, the entanglement of micelles progresses over time and the viscosity increases, and it is presumed that the treatment liquid T-2 has time dependency on the viscosity characteristics with respect to temperature.

  Therefore, the present invention is superior in manufacturing suitability such as filterability at the time of preparation of the treatment liquid by using a treatment liquid having a time dependency on the viscosity characteristic with respect to temperature like the treatment liquid T-2, and the intermediate transfer body 12. Excellent transferability of the processing liquid to the surface, and during image formation, once heated, the processing liquid will be reduced in viscosity even if cooled immediately. It is proposed that an ink jet recording apparatus can be realized.

  In Table 2, an example of preparation of 2-pyrrolidone-5-carboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), which is an ink aggregating agent, is 5% by weight to 20% by weight.

[Ink adjustment]
An adjustment example of the ink used in the present embodiment is shown below.

(Polymer dispersion) Preparation of cyan ink In a reaction vessel, 6 parts by mass of styrene, 11 parts by mass of stearyl methacrylate, 4 parts by mass of styrene macromer AS-6 (manufactured by Toa Gosei), 5 parts by mass of Plenmer PP-500 (manufactured by NOF Corporation) Then, 5 parts by mass of methacrylic acid, 0.05 part by mass of 2-mercaptoethanol, and 24 parts by mass of methyl ethyl ketone were prepared.

  On the other hand, 14 parts by mass of styrene, 24 parts by mass of stearyl methacrylate, 9 parts by mass of styrene macromer AS-6 (manufactured by Toa Gosei), 9 parts by mass of Plenmer PP-500 (manufactured by NOF Corporation), 10 parts by mass of methacrylic acid, 2 -A mixed solution was prepared by adding 0.13 parts by weight of mercaptoethanol, 56 parts by weight of methyl ethyl ketone, and 1.2 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile).

  While stirring the mixed solution in the reaction vessel under a nitrogen atmosphere, the temperature was raised to 75 ° C., and the mixed solution in the dropping funnel was gradually dropped over 1 hour. After 2 hours from the end of the dropwise addition, a solution prepared by dissolving 1.2 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) in 12 parts by weight of methyl ethyl ketone was added dropwise over 3 hours, and further at 75 ° C. for 2 hours. Aging was carried out at 80 ° C. for 2 hours to obtain a polymer dispersant solution.

  A part of the obtained polymer dispersant solution was isolated by removing the solvent, and the obtained solid content was diluted to 0.1% by mass with tetrahydrofuran to obtain a high-speed GPC (gel permeation chromatography) HLC- Three TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ2000 were connected in series with 8220GPC, and the weight average molecular weight was 25,000 in terms of polystyrene.

  5.0 g of the obtained polymer dispersant in terms of solid content, 10.0 g of cyan pigment Pigment Blue 15: 3 (manufactured by Dainichi Seika), 40.0 g of methyl ethyl ketone, 8.0 g of 1 mol / L sodium hydroxide, ion-exchanged water 82.0 g and 300 mm of 0.1 mm zirconia beads were added to the vessel and dispersed with a ready mill disperser (manufactured by Imex) at 1000 rpm for 6 hours. The obtained dispersion was concentrated under reduced pressure using an evaporator until methyl ethyl ketone was sufficiently distilled off, and concentrated until the pigment concentration was 10%. The resulting cyan dispersion had a pigment particle size of 77 nm.

  Ink was prepared using cyan dispersion so as to have the composition shown in [Table 3]. After the preparation, coarse particles were removed with a 5 μm filter to prepare cyan ink (C1-1). As a result of measuring physical properties of the obtained cyan ink C1-1, it was found that the pH was 9.0, the surface tension was 32.9 mN / m, and the viscosity was 3.9 mPa · s.

  In the same manner as described above, magenta, yellow, and black inks were also prepared.

  Glycerin and diethylene glycol may be changed to a high boiling point solvent such as DEGmEE.

[Additional polymer]
Particles (polymer particles, latex) such as polymer resin are appropriately added to the treatment liquid (aggregation treatment agent) and ink described above. It is desirable to add particles having a particle diameter of 1 to 5 μm and a melting point of 60 to 120 ° C. for fixing the coloring material and improving the transfer to the processing liquid, and the ink has a particle diameter of 1 μm or less and a glass point transfer point of 40 to 60 for fixing the image. It is preferable to add 1 to 5% of particles at ° C. Table 4 shows an example.

  When microcapsules are added to the processing solution, the particle size is 1 μm, in which higher alcohols or esters are encapsulated in a film agent such as polyvinyl alcohol from the viewpoints of storage stability, heat-pressure breakability, transfer cleaning properties, fixing properties, etc. A coacervation method is preferably used as described above, and the formation method by the coacervation method is disclosed in Japanese Patent Application Laid-Open No. 06-219924 (the capsule contents are not leaked in the surfactant during the production and storage, the capsules are not precipitated) The microcapsule-containing face wash that can be easily disintegrated by hand pressure during use and can exhibit a sufficient function. Note that a microcapsule liquid in which a film agent is formed of gelatin or the like may be applied separately from the treatment liquid.

  When the polymer particles and microcapsules are added to the treatment liquid in this way, the releasability is promoted by the action of the polymer particles and microcapsules remaining on the intermediate transfer body 12, and the transferability in the transfer portion 26 is further improved. An effect is obtained. Further, since nuclei are imparted on the intermediate transfer body 12, the repellency of the processing liquid is further reduced even with the low surface energy intermediate transfer body 12, and the coating stability is further improved.

[Configuration of treatment liquid application part]
(First example of liquid application device)
FIG. 8 is a configuration diagram illustrating a first example of a liquid coating apparatus applied to the treatment liquid coating unit 16. In the figure, the intermediate transfer body 12 is conveyed from left to right (in the direction of arrow A in the figure). The liquid coating apparatus 100 shown in FIG. 8 presses the gravure roller 38 against the intermediate transfer body 12 to be conveyed, and the gravure roller 38 is in a direction opposite to the conveyance direction of the intermediate transfer body 12 (counterclockwise in FIG. 8). Device for selectively applying a treatment liquid to a desired area of the intermediate transfer body 12 by rotating at a predetermined constant speed (here, the application area in the intermediate transfer body conveyance direction is controlled). Stuff).

  In the liquid coating apparatus 100 of this example, the processing liquid is pumped up by the liquid feed pump 104 from the processing liquid supply tank 102 that stores the processing liquid, and the processing liquid is introduced into the processing liquid container 40. A drain flow path 106 is provided at a predetermined height from the bottom surface of the processing liquid container 40, and the overflowed liquid returns to the processing liquid supply tank 102 via the drain flow path 106, so that the processing in the processing liquid container 40 is performed. The liquid level of the liquid 108 is kept constant. The processing liquid supply tank 102 is provided with a temperature controller 122 for heating the processing liquid.

  The gravure roller 38 is a coating roller in which a large number of precise cells (see FIGS. 9A and 9B) engraved in a pyramid shape or a lattice shape (pyramidal frustum shape) are formed on the surface thereof at a predetermined density. And has a length (width dimension) equal to or greater than the width dimension of the coated surface of the intermediate transfer body 12. The arrangement form of the cells on the roller surface is not particularly limited, but a form in which the cells are arranged along an oblique line that is not orthogonal to the rotation direction is preferable. The cell shape, depth, cell volume, density, and the like are appropriately selected according to the amount of liquid to be applied (the thickness of the liquid film after application). The gravure roller is also called an anilox roller or a precision roller.

  As shown in FIG. 8, a part of the gravure roller 38 (the lower part in FIG. 8) is immersed in the processing liquid 108 in the processing liquid container 40, so that the processing liquid enters the cell and the surface of the roller is processed. Liquid adheres.

  In the processing liquid container 40, a squeegee blade 110, which is a squeegee member, is erected as a means for scraping off the excess processing liquid from the outer peripheral surface of the gravure roller 38. The squeegee blade 110 is disposed so that the tip thereof is in contact with the gravure roller 38, and the tip is biased in a direction of pushing the peripheral surface of the gravure roller 38. The urging force may be due to elastic deformation of the squeegee blade 110 itself, or may be applied from the outside using a spring or other urging member (not shown).

  While rotating the gravure roller 38 immersed in the treatment liquid 108, the excess liquid of the treatment liquid is scraped off by the squeegee blade 110, so that only the treatment liquid held in the groove passes through the squeegee blade 110.

  In the present embodiment, from the viewpoint of controlling the application range of the processing liquid in the conveyance direction of the intermediate transfer body 12, in the liquid application device 100, on the downstream side of the squeegee blade 110 with respect to the rotation direction of the gravure roller 38. The shielding member 112 is disposed so as to restrict (limit) the opening range of the surface of the gravure roller 38 in the rotation direction, and the surface of the gravure roller 38 exposed between the shielding member 112 and the squeegee blade 110 (the opening range described above). On the other hand, as shown in the drawing, a replacement fluid ejecting unit 114 that ejects a liquid such as water or a gas such as air (hereinafter collectively referred to as “replacement fluid”) from obliquely above is provided.

  The replacement fluid ejection unit 114 has an ejection range in which the substitution fluid is sprayed over the entire width of the gravure roller 38. By ejecting the replacement fluid from the replacement fluid ejecting unit 114, the processing liquid is removed from the cell of the gravure roller 38. That is, when a liquid is used as the replacement fluid, the processing liquid in the cell is replaced with the replacement fluid liquid. On the other hand, when a gas such as air injection is used, the processing liquid is blown out from the cell (replaced by air).

  By controlling the removal range of the processing liquid from the gravure roller 38 by the ejection of the replacement fluid, the application range of the processing liquid to the intermediate transfer body 12 (area in the intermediate transfer body conveyance direction) can be controlled. By selectively ejecting the replacement fluid onto the area corresponding to the non-image forming portion on the intermediate transfer body 12, the processing liquid is not applied to the non-image forming portion on the intermediate transfer body 12, and the image The treatment liquid can be applied only to the formation part (see FIG. 19A).

  According to this aspect, application of the processing liquid to an unnecessary area can be suppressed, and adhesion of the aggregation processing liquid to the pressure roller 48 can be prevented even when an image is transferred and formed discontinuously on cut paper or the like. For this reason, operation | movement of an apparatus is stabilized and reliability, such as a stain | pollution | contamination and corrosion over time, also improves.

  As the material of the gravure roller 38, it is common to subject the steel material to a hard treatment such as hard chrome plating. preferable. Also, a material such as SUS304 or SUS316 is preferable from the viewpoint of ensuring the wettability of a liquid such as the treatment liquid (Example 2) shown in Table 2 above.

  A liquid having a viscosity of 20 mPa · s or more and 100 mPa · s or less containing a surfactant such as the treatment liquid (Example 2) shown in Table 2 above is effective for lubrication and coating between the gravure roller 38 and the squeegee blade 110. Is good. Further, in this embodiment, no repelling phenomenon occurs in the silicone rubber, fluororubber, or fluorine-based elastomer (Shin-Etsu Chemical Co., Ltd .: SIFEL600 series, etc.) that coats the intermediate transfer body 12, so that the intermediate transfer body 12 is surely liquid. Is preferable in that it can be applied.

  Applying the liquid coating apparatus 100 of this embodiment to the application of the processing liquid to the intermediate transfer body 12 that performs liquid cleaning as described later removes the processing liquid by the replacement fluid ejecting unit 114 due to residual components of the liquid cleaning. Even in this case, it is preferable in that the contact friction between the gravure roller 38 and the intermediate transfer body 12 can be reduced.

  Further, when a treatment liquid, a penetration inhibitor, or the like is applied to the intermediate transfer member 12, the contact friction between the gravure roller 38 and the intermediate transfer member 12 can be reduced by a lubricating effect, as in the case of the residual component of the liquid cleaning. Can do.

The outer surface (particularly the groove) of the gravure roller 38 is subjected to a liquid repellent treatment such as electroless PTFE (polytetrafluoroethylene) eutectoid plating or PFA (paraformaldehyde) coating to give a surface energy of 25 mN / m (= mJ / m). ² ) It is preferable that the releasability of the aggregating agent is improved if it is about 40 mN / m or less, and the surface tension of the aggregating agent is 18 mN / m (= mJ / m ² ) or more and 28 mN / m or less ( Table 1 and Table 2) are low, so it is possible to ensure applicability.

  The rotational drive means (not shown) of the gravure roller 38 is preferably a direct drive (direct shaft connection) by an inverter motor, but is not limited to such a configuration, and combinations of various motors and speed reducers (gears, etc.) A combination of various motors and winding transmission means such as a timing belt may be used.

  Further, the gravure roller 38 is supported by a movement mechanism (contact / separation mechanism) (not shown) so as to be movable in the vertical direction in FIG. 8, and the gravure roller 38 is pressed against the intermediate transfer body 12 ( Control can be performed to switch between the nip state shown in FIG. 8 and the state separated (retracted) from the intermediate transfer body 12.

  On the opposite side (upper side in FIG. 8) of the gravure roller 38 with the intermediate transfer body 12 interposed therebetween, press rollers 116 and 118 are arranged. The two pressing rollers 116 and 118 are arranged in parallel at a predetermined interval in the conveyance direction of the intermediate transfer body 12, and the gravure roller 38 is arranged with two pressing rollers 116 and 118 in the conveyance direction of the intermediate transfer body 12. It is located approximately in the middle of 118.

  At the time of application, as shown in the figure, the gravure roller 38 is pressed against the intermediate transfer member 12 and the intermediate transfer member 12 is pushed up between the pressing rollers 116 and 118. The intermediate transfer body 12 sandwiched between the pressing rollers 116 and 118 and the gravure roller 38 is curved along the upper peripheral surface of the gravure roller 38, thereby improving the adhesion with the gravure roller 38 and securing a contact area. By controlling the pressing amount of the gravure roller 38 against the intermediate transfer member 12, the winding angle of the intermediate transfer member 12 with respect to the gravure roller 38 can be adjusted.

  In this nip state, the intermediate transfer member 12 is conveyed at a constant speed, and the gravure roller 38 is rotated in the reverse direction with respect to the intermediate transfer member conveyance direction, so that it is homogeneous on the image forming surface 12A of the intermediate transfer member 12 as a member to be coated. Thin film coating by film thickness is possible. At this time, as the intermediate transfer body 12 is conveyed, the pressing rollers 116 and 118 rotate in a rotation direction following the conveyance direction.

  In the liquid coating apparatus 100 of this example, in particular, if the density of the cells of the gravure roller 38 is 100 to 250 lines / inch, the visibility of the coating pattern is low, and a thin film coating with a coating thickness of 1 μm or more and about 25 μm or less is possible. It is. Furthermore, if a cell density of 150 to 200 lines / inch and a viscosity of 15 mPa · s to 60 mPa · s is used, a homogeneous liquid film of 2 μm to 10 μm can be formed. No liquid flow occurs on the transfer body. Further, when air is ejected from the replacement fluid ejecting unit 114 as the replacement fluid to remove the processing liquid from the cells of the gravure roller 38, the liquid scattering is reduced. Furthermore, it is more preferable in that the color material fixing property at the time of ink ejection is also good.

  Here, as the treatment liquid to be used, the above-mentioned treatment liquid T-2 containing a fluorosurfactant and having time dependency with respect to viscosity characteristics with respect to temperature can be considered.

  Here, a visibility curve 600 is shown in FIG. The visibility curve 600 is a curve showing a boundary that is visually recognized as density unevenness when the horizontal axis is the spatial frequency and the vertical axis is the density difference (ΔD) of the spatial frequency period. The region above the visibility curve 600 is likely to be visually recognized as uneven density, and the region below the visibility curve 600 is difficult to be visually recognized as uneven density. According to the visibility curve 600, in particular, 30 to 50 lines / inch is highly visible as density unevenness, and becomes remarkable in the intermediate density region. If the number of grooves of the above-described gravure roller 38 is set to 100 to 200 / inch, the cell traces exceed the human visual frequency, and the visibility becomes low. Therefore, the image quality of the recording medium 14 can be kept good.

  The roller member for application is not limited to the gravure roller 38, and as shown in FIG. 9C, a spiral roller 39 (for example, “manufactured by OSG Corporation” having a spiral groove formed on the surface thereof is used. It is also possible to use a coating bar such as “D-Bar” (trade name) or a known wire bar. The groove shape, pitch a, groove depth b, and the like of the spiral roller 39 are appropriately selected according to the amount of liquid to be applied (the thickness of the liquid film after application). For example, in the case of the liquid coating apparatus 100 of this embodiment, a spiral roller having a pitch a = 0.08 to 0.2 mm and a groove depth b = 5 to 20 μm is suitable.

  Furthermore, in the liquid coating apparatus 100 of the present example, the squeegee blade 110 and the replacement fluid ejecting unit 120 are disposed so that the processing liquid removed by ejecting the replacement fluid flows down substantially along the squeegee blade 110 from the ejection position. Has been. That is, in FIG. 8, the tip of the squeegee blade 110 abuts substantially at the 3 o'clock position of the gravure roller 38, and the replacement fluid sprayed to the region between the squeegee blade 110 and the shielding member 112 from the gravure roller 38. The removed liquid (including the replacement fluid when the replacement fluid is a liquid) flows down in the direction of gravity along the slope 110A of the squeegee blade 110. Thereby, the liquid pool at the tip of the squeegee blade 110 is prevented, and the removal liquid is prevented from being scattered while improving the controllability of the removal.

  Further, the squeegee blade 110 of this example is also used as a partition member (partition wall member) that partitions the inside of the processing liquid container 40. In FIG. 8, the left side of the squeegee blade 110 is a region for storing the processing liquid 108 (a portion functioning as a coating liquid dish), and the right side is a recovery region for recovering the removal liquid removed by the replacement fluid. A treatment liquid discharge port 124 is formed at the bottom of the region of the treatment liquid container 40 where the treatment liquid 108 is stored. The processing liquid discharge port 124 is connected to a processing liquid recovery tank 128 via a processing liquid discharge valve 126.

  If the processing liquid discharge valve 126 is opened, the processing liquid 108 can be extracted from the processing liquid container 40, and the processing liquid is discharged into the processing liquid container 40 by closing the processing liquid discharge valve 126 and driving the liquid feed pump 104. 108 can be saved.

  On the other hand, a removal liquid discharge port 130 is formed at the bottom of the collection region of the removal liquid partitioned by the squeegee blade 110, and the removal liquid discharge port 130 is connected to the removal liquid collection tank 134 via the removal liquid discharge valve 132. It is connected to the.

  Thus, by forming a partition with the squeegee blade 110 itself, the aggregating treatment liquid and the removal liquid can be separated, and the removal liquid can be independently recovered. If air is used as the replacement fluid, it can be removed with a simple structure, and the surfactant or high boiling point slightly remaining on the intermediate transfer body 12 that has passed through the first cleaning unit 30 (see FIG. 1). Since the solvent serves as a lubricant, damage to the intermediate transfer body 12 can be prevented even when the coating liquid on the roller surface is removed using air. Furthermore, the liquid recovered as the removal liquid can be reused as the coating liquid for coating.

  On the other hand, if a liquid or liquid mist is used as a replacement fluid, the lubrication effect is improved. In particular, if water such as purified water is used, the aggregating treatment agent is effectively diluted and washed to 15 mN / m (= mJ / m2) or more. In the intermediate transfer body 12 having a low surface energy of about 30 mN / m or less, the adhesion amount of the aggregating agent is small, and drying in the aggregating agent heating part is possible, so that more stable removal is possible.

  As an example of an injection member applied to the replacement fluid injection unit 114, in the case of air injection, a line in which nozzles 140 having a diameter of about 0.5 to 1 mm are arranged in the width direction at a pitch of 1 to 3 mm on the injection surface as shown in FIG. A spray 142 can be used. A plurality of such line sprays 142 are arranged as shown in FIG. 12 to achieve a required injection width, and a substantially uniform impact force (impact) 500 over the entire area of the spray surface within a pressure range of 0.1 to 0.5 MPa. ˜1500 mN can be provided.

  In the case of liquid injection, for example, a one-fluid flat spray nozzle having an orifice diameter of about 0.2 to 0.6 mm and an injection angle of 60 to 100 ° can be used. As shown in FIG. 13, since the fluid is ejected at the spray angle α, the flat spray nozzle defines the substantial spray width Wsp of the spray range 148 according to the distance L between the discharge surface of the nozzle body 144 and the spray surface 146. Is done. The flat spray nozzle is not limited to a single mode, and a plurality of flat spray nozzles may be arranged in the width direction of the gravure roller 38. In this case, removal control in the width direction can be performed in addition to the transport direction.

  According to the inkjet recording apparatus 10 including the liquid coating apparatus 100 of this example, when the apparatus is on standby or stopped, the gravure roller 38 is rotated by putting a cleaning liquid in the processing liquid container 40 instead of the processing liquid 108, The processing liquid on the roller outer peripheral surface is surely removed, and it is possible to prevent sticking of the residual processing liquid and deterioration of the roller outer peripheral surface due to the acidic residual processing liquid, thereby enabling stable operation of the apparatus.

  In addition, it is preferable to provide the film thickness detecting means 136 such as a moisture meter or a film thickness meter in the gravure roller 38 or the intermediate transfer body 12 because the coating thickness in the coating state can be kept stable.

  Further, it is preferable to set the viscosity of the treatment liquid (coating liquid) to about 20 mPa · s or more and 100 mPa · s or less because the separation property of the intermediate transfer body 12 is improved in addition to the above-described coating properties.

  Further, since a tension roller 34C, which is a tensioner member of the intermediate transfer body 12, is provided in the vicinity of the gravure roller 38 (see FIG. 1), the intermediate transfer body 12 is absorbed by absorbing the speed fluctuation of the intermediate transfer body 12 during drawing. A stable treatment liquid can be applied, and image distortion can be prevented.

  Further, by making the surface of the intermediate transfer body 12 an elastic body having a hardness of 20 to 80 °, the contact of the gravure roller 38 is stabilized and the application is made uniform. Furthermore, by using any one of fluoro rubber, urethane rubber, silicone rubber, fluoro elastomer, and silicon elastomer as the surface material of the intermediate transfer body 12, the surface tension (surface energy) can be set to 10 to 40 mN / m, and Since liquidity can be secured, it is excellent in cleaning properties.

(Second example of liquid application device)
Next, a second example of the liquid application device applied to the treatment liquid application unit 16 will be described. The one-fluid flat spray nozzle exemplified above can control the spray angle (spray angle) by adjusting the spray pressure. In addition, by using a pressurized two-fluid flat spray nozzle (two-fluid air atomizing nozzle) that sprays in a state of being atomized by mixing air and liquid, the jet can be controlled by controlling the combination of air pressure and liquid flow rate. The corner can be controlled.

  Therefore, by applying the treatment liquid to the gravure roller 38 using such an ejection angle variable ejection nozzle, only the application liquid application area in the intermediate transfer body conveyance direction can be obtained without arranging a plurality of removal nozzles in the width direction. It is also possible to change the applied width in the width direction orthogonal to this.

  The second example of the liquid application apparatus shown in FIG. 14 is an apparatus that can control the application range in the width direction and the conveyance direction of the intermediate transfer body 12. 14, members that are the same as or similar to those in the configuration described in FIG. 8 are given the same reference numerals, and descriptions thereof are omitted.

  The liquid application apparatus 150 according to the second example illustrated in FIG. 14 includes a liquid ejecting unit 152 as a means for applying the treatment liquid to the gravure roller 38. As the ejecting member of the liquid ejecting unit 152, a one-fluid flat spray nozzle capable of controlling the ejecting angle or a pressurized two-fluid flat spray nozzle is applied. Specifically, for example, a one-fluid flat spray in which an orifice angle of about 0.2 to 0.4 mm and an injection angle of 60 to 100 ° are realized, and a pressurized two-fluid flat spray having the same size as this can be used.

  As shown in FIG. 14, the liquid ejecting unit 152 ejects the processing liquid from below the gravure roller 38 toward the tip of the squeegee blade 110. At that time, the jetting pressure is controlled so that the jetting angle is a given width that matches the width of the image forming area. That is, the liquid ejecting unit 152 controls the width of supplying the processing liquid on the outer peripheral surface of the gravure roller 38 as supply width control means for controlling the width of supplying the processing liquid.

  As shown in FIG. 15, the liquid spray pattern by the flat spray has a liquid amount distribution in the width direction. Also, the injection amount (flow rate) changes depending on the injection pressure. However, in the case of this example, since the excess processing liquid is removed by the squeegee blade 110 so that a paper width range wider than the width of the effective image area can be applied, the application amount of the processing liquid to the gravure roller 38 is consequently reduced. It can be kept stable, and uniform application with controlled application width is possible.

  If a spiral roller having a spiral groove is used instead of the gravure roller 38, the overflow of the processing liquid in the width direction can be reduced due to the unevenness of the groove. For this reason, the width controllability is further improved, and the contact friction can be reduced even for the non-coated portion in the width direction due to the residual component of the liquid cleaning and the lubrication effect of the coated paper.

  The configuration for selectively removing the processing liquid with respect to the circumferential direction of the gravure roller 38 by fluid ejection from the replacement fluid ejecting unit 114 is as described in the first example.

  Further, the squeegee blade 110 in FIG. 14 is also used as a partition wall of the processing liquid container 40, and the left side of the squeegee blade 110 is an area for storing the processing liquid 108 (a part functioning as a coating liquid dish), and the right side is a replacement fluid. It is the same as that of the first example in that it becomes a recovery area for recovering the removal liquid removed by the above.

  According to the liquid coating apparatus of the second example having the above-described configuration, the treatment liquid application width in the width direction is controlled by the liquid ejecting unit 152, and the intermediate transfer member conveyance direction (circumference in the gravure roller 38 is controlled by the replacement fluid ejecting unit 114. Direction) treatment liquid application range is controlled.

  Further, when the treatment liquid T-2 having a viscosity of 15 mPa · s or more and 60 mPa · s or less is used as the treatment liquid, liquid dispersion occurs when the treatment liquid is applied to the gravure roller 38 by the liquid ejecting unit 152. Is reduced.

  FIG. 16 is an explanatory diagram schematically illustrating the relationship between the liquid ejecting unit 152 and the replacement fluid ejecting unit 114. As shown in the drawing, the nozzles of the liquid ejecting unit 152 can switch at least two types of ejection widths (ejection ranges in the width direction). Although FIG. 16 shows an example in which two types of injection widths are realized by the strength of the injection pressure, an aspect in which three or more types of injection widths are realized corresponding to the paper size type of the recording medium 14 is also possible. . Information on the recording medium 14 may be automatically acquired by a sensor or the like, or may be acquired by being input by an operator.

  The nozzle of the replacement fluid ejecting unit 114 has an ejection width larger than the maximum ejection width (in the illustrated case, the ejection width when the ejection pressure is high) by the liquid ejecting unit 152. For the replacement fluid injection unit 114, the injection width is not required, so that the injection pressure is constant, and only the replacement fluid injection (on) / non-injection (off) is controlled. In this embodiment, the ejection width of the replacement fluid ejecting unit 114 is fixed from the viewpoint of simplifying the device configuration, but the ejection width of the replacement fluid ejecting unit 114 is switched according to the switching of the ejection width of the liquid ejecting unit 152. A configuration may be adopted.

  FIG. 17 is a configuration example of a liquid supply system when gas (air) is used as a replacement fluid. The nozzle body 160 of the replacement fluid ejecting unit 114 is connected to the compressor 170 via an electromagnetic valve 162, a manual valve 164, and a precision regulator 168. Compressed air from the compressor 170 is maintained at a predetermined pressure by the precision regulator 168, and air injection (on) / non-injection (off) from the nozzle body 160 is controlled by on / off control of the electromagnetic valve 162. Thereby, the air injection pressure from the nozzle body 160 becomes constant, and a predetermined injection width is realized.

  The nozzle body 180 of the liquid ejecting unit 152 is connected to the liquid layer 186 in the pressure vessel 185 via an electromagnetic valve 182 and a manual valve 184. A liquid for injection (in this case, a processing liquid) is stored in the sealed pressure vessel 185, and the gas layer 187 of the pressure vessel 185 is a variable precision regulator 188 capable of controlling pressure change. To the compressor 170. Further, a temperature controller 183 is provided in the pressure vessel 185.

  By controlling the variable precision regulator 188 to change the pressure in the pressure vessel 185, the pressure of the liquid delivered from the pressure vessel 185 is adjusted. The liquid heated to a predetermined temperature by the temperature controller 183 is sent out from the pressure vessel 185 and sent to the nozzle body 180 through the electromagnetic valve 182. The injection (on) / non-injection (off) of the liquid from the nozzle body 180 is controlled by the on / off control of the electromagnetic valve 182, and the injection pressure, that is, the injection from the nozzle body 180 is controlled by the pressure control of the variable precision regulator 188. The width is changed. When a two-fluid air atomizing nozzle is used as the nozzle body 180 of the liquid ejecting unit 152, compressed air is supplied to the air supply unit 189 of the nozzle body 180 via a regulator (not shown). It becomes composition.

  Although the details of the supply system in the case of using a liquid as the replacement fluid are not shown, a liquid supply system similar to the processing liquid instead of the air supply system to the nozzle body 160 shown in FIG. 17 (however, pressure control is not required). Applies.

  FIG. 18 is another configuration example of the liquid supply system of the liquid ejecting unit 152. The nozzle body 180 of the liquid ejecting unit 152 is connected to the storage container 193 via an electromagnetic valve 181, a manual valve 190, and a liquid feed pump 191. The storage container 193 stores a jetting liquid (in this example, a processing liquid), and the storage container 193 discharges a processing liquid for reusing the processing liquid sprayed from the nozzle body 180. The outlet 124 and the filter 195 are connected.

  Under such a configuration, the liquid heated to a predetermined temperature by the temperature controller 197 is sent from the storage container 193 by controlling the liquid feed pump 191, and is sent to the nozzle body 180 via the electromagnetic valve 181. Sent. The on / off control of the solenoid valve 181 controls the injection (on) / non-injection (off) of the liquid from the nozzle body 180.

  A control example of application of the treatment liquid to the intermediate transfer body 12 according to the configuration of the first example and the second example will be described with reference to FIG. FIG. 19A shows the application range (application area) controlled in the transport direction of the intermediate transfer body 12 by applying the first example. FIG. 19B is a diagram in which the application range is controlled in the width direction and the conveyance direction of the intermediate transfer body 12 by applying the second example.

  The intermediate transfer body 12 has a larger width than the area of the effective image area 192 where the primary image to be transferred is formed, and a wider area than the effective image area 192 (coating corresponding to the recording medium size indicated by reference numeral 194). The processing liquid is applied to the area).

  FIG. 19C shows the timing of the ejection control of the replacement fluid in the first example and the second example (corresponding to the timing of the on / off control of the electromagnetic valve 162 shown in FIG. 17). FIG. 19D shows the application control of the coating liquid (processing liquid) to the gravure roller 38 in the first example and the second example.

  As shown in FIG. 19D, the gravure roller 38 itself is continuously applied with a coating liquid (treatment liquid), and the coating range in the transport direction is controlled by the control of the replacement fluid shown in FIG. (See FIGS. 19A and 19B).

  In the configuration of the liquid coating apparatus 150 according to the second example, the ejection pressure of the liquid ejection unit 152 is controlled to change the coating range in the width direction in response to the change in the paper size of the recording medium 14.

  According to the liquid coating apparatuses 100 and 150 according to the present embodiment, the following operational effects can be obtained.

  (1) The replacement fluid is sprayed onto a partial area (area corresponding to the non-image forming portion) of the gravure roller 38 to which the coating liquid (processing liquid in this example) has been applied, and the coating liquid adhering to the area is discharged. Since it is configured to be removed (replaced), it is possible to selectively remove the coating liquid (“treatment liquid”) attached to the non-image forming area.

  In addition, since the ejection of the replacement fluid is performed on the portion corresponding to the non-image forming area of the intermediate transfer body 12 with an ejection width wider than the application width of the processing liquid, reliable removal is possible.

  (2) The configuration and arrangement of the squeegee blade 110 and the arrangement of the replacement fluid ejecting section are devised so that the excess coating liquid and the ejected fluid removed by the ejection of the replacement fluid flow down along the squeegee blade 110. The accumulation of the coating liquid at the tip of the squeegee blade 110 in contact with the gravure roller 38 is unlikely to occur, thickening is prevented, and good control of liquid breakage in the rotational direction can be realized.

  (3) Since the partition wall of the processing liquid container 40 is formed by the squeegee blade 110 itself, and an independent discharge port (liquid recovery port indicated by reference numerals 124 and 130) is provided for each space partitioned by the partition wall, the squeegee The coating liquid scraped off by the blade 110 can be separated from the liquid removed by the replacement fluid (if the replacement fluid is a liquid, the liquid mixture of the removed coating liquid and the replacement liquid). Can be recovered independently.

(4) The surface tension of the liquid ejected as the replacement fluid is 60 to 80 mN / m (water not containing a surfactant such as distilled water), and the surface energy of the intermediate transfer member is 15 to 30 mN / m (= mJ / m ² ). Since the surface tension of the replacement fluid is larger than the surface energy of the intermediate transfer member, the adhesion of the replacement fluid to the intermediate transfer member can be reduced, and the coating liquid components can be effectively diluted and removed. Is possible. Further, the intermediate transfer member having a low surface energy has a small amount of attached liquid and can be removed by heating.

  (5) As described in the second example, the application liquid is applied to the gravure roller 38 by spraying the liquid using a flat spray (flat type line spray), and thus the opening slit formed by the squeegee blade 110 and the shielding member 112. In addition to control, the application width can be controlled by jet pressure control.

  In particular, in a mode in which liquid spraying by flat spray is performed on the intermediate transfer body 12 after the liquid cleaning process by the first cleaning unit 30, since the thin film remaining in the liquid cleaning process becomes a lubricating layer, the coating liquid for the gravure roller 38 is used. Even at the non-attached portion, it is possible to prevent the intermediate transfer body 12 from being worn.

  (6) During non-image formation such as when the apparatus is on standby or when it is stopped, the coating liquid is not applied to the gravure roller (from the processing liquid container 40 in the first example, from the liquid ejecting unit 152 in the second example). Spraying), and by continuously applying a replacement fluid (gas or liquid) for a predetermined time, the surface of the gravure roller is cleaned, and the adhesion of the coating liquid and the attack by the coating liquid component (acid in this example) are also reduced. it can. In particular, cleaning is more effective if a liquid with few impurities such as distilled water is used as the replacement fluid.

[Configuration of solvent removal unit]
FIG. 20 is an enlarged view of the solvent removal unit 24. In the figure, the intermediate transfer body 12 is conveyed from right to left. The solvent removing unit 24 shown in FIG. 20 brings the solvent removal roller 42 (roller member) into contact with the intermediate transfer body 12 to be conveyed, so that the intermediate transfer body 12 is conveyed in the conveyance direction (clockwise direction in FIG. 20). It is means for rotationally driving at a predetermined constant speed.

  The solvent removal roller 42 traps a liquid in a groove (cell) on the surface by a capillary force or the like by a groove structure similar to the gravure roller 38 of the treatment liquid application unit 16. More specifically, the solvent removal roller 42 has a predetermined density of precise cells (see FIGS. 9A and 9B) engraved on its surface with irregularities such as pyramid type and lattice type (pyramidal frustum type). A large number of gravure rollers are formed and have a length (width dimension) equal to or greater than the width dimension of the coated surface of the intermediate transfer body 12. The arrangement form of the cells on the roller surface is not particularly limited, but a form in which the cells are arranged along an oblique line that is not orthogonal to the rotation direction is preferable. The shape, depth, cell volume, density, etc. of the cell are appropriately selected according to the amount of liquid to be removed.

  Here, as shown by the visibility curve 600 in FIG. 10, the region above the visibility curve 600 is likely to be visually recognized as uneven density, and the region below the visibility curve 600 is not easily recognized as uneven density. According to the visibility curve 600, in particular, when the number of cell lines is 30 to 50 lines / inch, the visibility is high as the density unevenness, and becomes remarkable in the intermediate density region. If the number of cells of the solvent removal roller 42 described above is 100 to 200 lines / inch, the cell traces exceed the human visual frequency and the visibility becomes low. Therefore, the image quality of the recording medium 14 can be kept good.

  In particular, if the cell shape is a lattice type, the amount of solvent recovered can be increased and the amount of solvent removed can be increased. In addition, as the solvent removal roller 42, a spiral roller having a groove shape such as an independent groove, a left-right spiral, a multiple spiral (not shown) in addition to a spiral shape may be used. When a spiral roller is used, it has a simple shape and a large amount of solvent can be recovered.

The surface tension of the solvent is as low as 20 to 30 mN / m depending on the aggregation treatment agent or the surfactant contained in the ink, and the wettability is good. For this reason, the surface of the solvent removal roller 42 (particularly the recesses) is subjected to a liquid repellent treatment such as electroless PTFE (polytetrafluoroethylene) eutectoid plating or PFA (paraformaldehyde) coating, and the surface energy is 25 to 40 mN / m (= mJ). / M ² ), the solvent can be efficiently trapped by the retention effect of the cell and the capillary phenomenon.

  When the solvent removal roller 42 is brought into contact with the conveyed intermediate transfer body 12, the solvent (residual solvent) component separated from the aggregate of pigment enters the cell and is collected. As a result, the solvent (residual solvent) separated from the pigment aggregates present on the intermediate transfer body 12 is removed.

  Further, a first squeegee blade 200 as a means for scraping off the solvent from the surface of the solvent removal roller 42 is erected on the downstream side in the rotation direction of the solvent removal roller 42 from the contact position with the intermediate transfer body 12. The first squeegee blade 200 is disposed such that the tip thereof is in contact with the solvent removal roller 42, and the tip is biased in a direction of pushing the peripheral surface of the solvent removal roller 42. The urging force may be due to elastic deformation of the first squeegee blade 200 itself, or may be applied from the outside using a spring or other urging member (not shown).

  Further, the surface of the solvent removal roller 42 is located downstream from the contact position with the intermediate transfer body 12 in the rotation direction of the solvent removal roller 42 and upstream of the first squeegee blade 200 with respect to the rotation direction of the solvent removal roller 42. The shielding member 202 is arranged so as to restrict (limit) the opening range of the opening in the rotation direction. Then, a gas for injecting a gas such as air from above as shown in FIG. 20 to the outer peripheral surface of the solvent removal roller 42 exposed between the shielding member 202 and the first squeegee blade 200 (the above opening range). An injection nozzle 45 is provided.

  The gas injection nozzle 45 has an injection range in which gas is blown over the entire width of the solvent removal roller 42. By injecting gas from the gas injection nozzle 45, the solvent is blown off from the cells formed on the outer peripheral surface of the solvent removal roller 42 and removed.

  Further, a second squeegee blade 204 as a means for scraping off the solvent from the surface of the solvent removal roller 42 is erected on the downstream side of the first squeegee blade 200 with respect to the rotation direction of the solvent removal roller 42. Then, with respect to the surface of the solvent removal roller 42 exposed between the second squeegee blade 204 and the first squeegee blade 200, a mist composed of gas (air, etc.) and liquid from the upper right as shown in FIG. A mist injection nozzle 43 for injecting a fluid (hereinafter referred to as mist) is provided. The mist injection nozzle 43 can change the amount of liquid applied to the surface of the solvent removal roller 42 by changing the liquid ratio of the mist-like fluid to be injected. Therefore, the gas ratio of the mist-like fluid can be set to 0, and only the gas can be injected.

  The mist injection nozzle 43 has an injection range in which mist or gas is sprayed over the entire width of the solvent removal roller 42. By spraying the mist from the mist spray nozzle 43 onto the solvent removal roller 42, the aggregation treatment agent layer on the intermediate transfer body 12 in contact with the solvent removal roller 42 in the portion where the mist is sprayed is dissolved and diluted. Solvent recovery by the solvent removal roller 42 is promoted for an image with a small number (a lot of white background).

  Further, if a high boiling point solvent contained in the treatment liquid or ink is added to the mist, it is effective for preventing drying in the transfer step in the transfer portion 26 and the cleaning step in the first cleaning portion 30. Further, if polymer fine particles contained in the ink are contained in the mist, the polymer can be applied to the entire paper, so that the texture of the paper to be transferred is made uniform and stabilized. An example of the liquid contained in the mist is shown in [Table 5].

  Further, as described above, only the gas can be ejected from the mist ejection nozzle 43. In this case, the solvent is blown off from the cell of the solvent removal roller 42 and removed.

  The rotational drive means (not shown) of the solvent removal roller 42 is preferably a direct drive (direct shaft connection) by an inverter motor, but is not limited to this configuration, and combinations of various motors and speed reducers (gears, etc.) A combination of various motors and winding transmission means such as a timing belt may be used.

  Further, the solvent removal roller 42 is supported by a movement mechanism (contact / separation mechanism) (not shown) so as to be movable in the vertical direction in FIG. 20, and the solvent removal roller 42 is pressed against the intermediate transfer body 12. Control can be performed to switch between a state (nip state shown in FIG. 20) and a state separated (retracted) from the intermediate transfer body 12.

  A tension roller 34B is disposed on the opposite side of the intermediate transfer body 12 from the solvent removal roller 42.

  If the cell density of the solvent removal roller 42 is set to 100 to 200 lines / inch, the visibility of the cell pattern of the solvent removal roller 42 on the transfer medium is low and the liquid layer thickness can be made uniform as described above.

  Further, the first squeegee blade 200 and the gas injection nozzle 45 are arranged so that the solvent removed by the gas injection flows down from the injection position along the first squeegee blade 200 to the discharge port 206 in the substantially lower right direction. ing. That is, in FIG. 20, the tip of the first squeegee blade 200 abuts substantially at the 2 o'clock position of the solvent removal roller 42, and the gas injected into the region between the first squeegee blade 200 and the shielding member 202 is used. The solvent removed from the solvent removal roller 42 flows down the discharge port 206 in the substantially lower right direction along the slope 200A of the first squeegee blade 200. This prevents liquid accumulation at the tip of the first squeegee blade 200 and prevents the solvent from scattering while improving the controllability of removal.

  In addition, the second squeegee blade 204 is disposed so that the excess liquid ejected from the mist ejection nozzle 43 flows down from the ejection position along the second squeegee blade 204 to the discharge port 208 in the substantially lower right direction. That is, in FIG. 20, the tip of the second squeegee blade 204 abuts substantially at the 4 o'clock position of the solvent removal roller 42, and the surplus liquid ejected from the mist spray nozzle 43 passes through the slope 204 A of the second squeegee blade 204. It flows down to the discharge port 208 in the substantially lower right direction. Thereby, liquid pooling at the tip of the second squeegee blade 204 is prevented, and scattering of the solvent is prevented while improving removal controllability.

  As an example of an injection member applied to the gas injection nozzle 45, a line spray 142 in which nozzles 140 having a diameter of about 0.5 to 1 mm are arranged in the width direction at a pitch of 1 to 3 mm on the injection surface as shown in FIG. be able to. By arranging a plurality of such line sprays 142 as shown in FIG. 12 above, the required spray width is realized, and the pressure force is in the range of 0.1 to 0.5 MPa, and the impact force (impact is generally uniform over the entire area of the spray surface. ) 500-1500 mN.

  As an example of the injection member applied to the mist injection nozzle 43, an air pressure of 0.2 to 0.6 MPa, a liquid pressure of 0 to 0.3 MPa, an air flow rate of 40 to 80 l / min, a liquid flow rate of 0 to 10 l / h, an injection angle. A two-fluid flat spray nozzle that can achieve 90 ° to 130 ° can be used. As shown in FIG. 13, since the fluid is ejected at the spray angle α in the flat spray nozzle, the actual spray range 148 depends on the distance L between the discharge surface of the nozzle body 220 (see FIG. 21) and the spray surface 146. Specific injection width Wsp is defined. The flat spray nozzle is not limited to a single mode, and a plurality of flat spray nozzles may be arranged in the width direction of the solvent removal roller 42. In this case, removal control in the width direction can be performed in addition to the transport direction.

  FIG. 21 is an explanatory diagram showing a configuration example of a gas / liquid supply system of the solvent removing unit 24. The nozzle body 210 of the gas injection nozzle 45 is connected to the compressor 218 via an electromagnetic valve 212, a temperature controller 213, a manual valve 214, and a variable precision regulator 216 capable of controlling pressure change. The pressure of the compressed gas (compressed air or the like) from the compressor 218 is adjusted by the variable precision regulator 216. Then, gas injection (ON) / non-injection (OFF) from the nozzle body 210 is controlled by ON / OFF control of the electromagnetic valve 212. As described above, an arbitrary injection width is realized while adjusting the gas injection pressure from the nozzle body 210.

  The compressed gas is heated to a predetermined temperature by the temperature controller 213. Therefore, the compressed gas is heated by the temperature controller 213, and the temperature of the gas ejected from the nozzle body 210 is the boiling point of the solvent after the treatment liquid and the ink react, specifically, water as the main component. By heating in the range below the boiling point and below the melting temperature of the polymer fine particles contained in the aggregation treatment agent or ink, the dissolution of the aggregation treatment agent layer and the releasability of the solvent removal roller 42 are improved. The effect of solvent removal is further increased.

  Specifically, when the polymer fine particles contained in the aggregating agent or ink are non-crystalline polymer fine particles, the heating temperature is adjusted within the range of the glass transition point or lower (for example, 50 ° C. or lower for acrylics). Is preferred. When the polymer fine particles contained in the aggregating agent or ink are crystalline polymer fine particles, the heating temperature is controlled within the melting point or lower (for example, 110 ° C. or lower for ethylene and 70 ° C. or lower for WAX). It is preferable to do this.

  The nozzle body 220 of the mist injection nozzle 43 is connected to the liquid layer 230 in the pressure vessel 228 via the electromagnetic valve 222, the temperature controller 224, and the manual valve 226. A liquid for injection is stored in the sealed pressure vessel 228, and the gas layer 232 of the pressure vessel 228 is connected to the compressor 218 via a variable precision regulator 234 capable of controlling change in pressure. Yes.

  By controlling the variable precision regulator 234 to change the pressure in the pressure vessel 228, the pressure of the liquid delivered from the pressure vessel 228 is adjusted. The liquid sent out from the pressure vessel 228 is heated to a predetermined temperature by the temperature controller 224 and sent to the nozzle body 220 through the electromagnetic valve 222. Further, the compressed gas is supplied to the gas supply unit 236 of the nozzle body 220 from the gas supply path to the nozzle body 210 of the gas injection nozzle 45 via the precision regulator 238.

  Mist can be ejected from the nozzle body 220 by the liquid delivered from the pressure vessel 228 and the compressed gas supplied via the precision regulator 238. If the supply of the liquid sent from the pressure vessel 228 is stopped by the on / off control of the electromagnetic valve 222, only the compressed gas supplied through the precision regulator 238 is obtained, and only the gas is injected from the nozzle body 220. Can do.

  In this manner, the mist or gas injection (ON) / non-injection (OFF) from the nozzle body 220 is controlled by the ON / OFF control of the electromagnetic valve 222.

  In addition, the liquid sent out from the pressure vessel 228 is heated by the temperature controller 224, and the temperature of the mist ejected from the nozzle body 220 becomes the boiling point of the solvent after the treatment liquid and the ink react, specifically, By heating in the range below the boiling point of water as the main component and below the melting temperature of the polymer fine particles contained in the aggregation treatment agent or ink, dissolution of the aggregation treatment agent layer or release of the solvent removal roller 42 is performed. Improves the effect of solvent removal.

  Specifically, when the polymer fine particles contained in the aggregating agent or ink are non-crystalline polymer fine particles, the heating temperature is adjusted within the range of the glass transition point or lower (for example, 50 ° C. or lower for acrylics). Is preferred. When the polymer fine particles contained in the aggregating agent or ink are crystalline polymer fine particles, the heating temperature is controlled within the melting point or lower (for example, 110 ° C. or lower for ethylene and 70 ° C. or lower for WAX). It is preferable to do this.

  In the mist injection nozzle 43, the compressed gas (compressed air or the like) from the compressor 218 is maintained at a predetermined pressure by the precision regulator 238 in the nozzle body 220. On the other hand, the injection width (injection pressure) from the nozzle body 220 is changed by controlling the variable precision regulator 234 to adjust the pressure of the liquid delivered from the pressure vessel 228.

  As a specific example, in the nozzle body 220, the pressure of the compressed gas from the compressor 218 is maintained at 0.4 MPa, and the pressure of the liquid delivered from the pressure vessel 228 is adjusted between 0 and 0.3 MPa. At this time, if the distance L (see FIG. 13) between the discharge surface of the nozzle body 220 and the spray surface 146 is 15 cm, the gas flow rate from the nozzle body 220 is 60 l / min, the injection width Wsp (see FIG. 13) is 60 cm, The liquid flow rate can be controlled to 0 to 10 l / h.

  Furthermore, if the ejection amount of the gas ejection nozzle 45 and the ejection amount of the mist ejection nozzle 43 are controlled according to the amount of liquid on the intermediate transfer body 12 (amount of solvent after the aggregation treatment agent and ink have reacted), The residual amount of solvent can be kept stable for both solid images and white images, and transferability and intermediate transfer member cleaning properties are improved.

  As a specific example, the thickness of the liquid (solvent) layer on the intermediate transfer body 12 is about 1 μm (solvent of the aggregation treatment agent) in the case of a white background image, and about 9 to 13 μm (2-3 of the aggregation treatment agent in the case of a solid image). Solvent after the reaction with the color ink. Therefore, by controlling the solvent removal roller 42, the thickness of the liquid layer on the intermediate transfer body 12 can be stabilized to about 3 to 7 μm. If the thickness of the liquid layer on the intermediate transfer body 12 is further reduced, a plurality of solvent removal rollers 42 may be provided.

  Here, FIG. 22 is a diagram illustrating an example of control regarding injection from the gas injection nozzle 45 and the mist injection nozzle 43. As an image formed on the intermediate transfer body 12, a solid image or the like is an image having a density of 80% or more and 100% or less, a halftone image is an image having a density of 20% or more and less than 80%, and a white background image is 0%. The image is less than 20%. The control in FIG. 22 is performed by determining the amount of liquid (solvent) on the intermediate transfer body 12 based on image data to be printed by a system controller (reference numeral 272 in FIG. 24).

  As shown in FIG. 22, when an image (including a solid image) having a higher density than the halftone image is formed on the intermediate transfer body 12 (an image density (solvent of 80% to 100%) in FIG. 22). In the case of (quantity), control is performed so that the gas injection amount from the gas injection nozzle 45 is large and only the gas is injected from the mist injection nozzle 43. In this way, when an image with a high density (including a solid image) is formed, the amount of liquid on the intermediate transfer body 12 is large, so a large amount of gas is produced in two stages by the gas injection nozzle 45 and the mist injection nozzle 43. It is jetting.

  When a halftone image is formed (in the case of an image density (solvent amount) of “20% to less than 80%” in FIG. 22), the gas injection amount from the gas injection nozzle 45 is set to a medium amount or a small amount. In addition, the mist injection nozzle 43 is appropriately controlled to select either gas-only injection or mist injection. More specifically, in the case of an image density (solvent amount) of “60% to less than 80%” in FIG. 22, the gas injection amount from the gas injection nozzle 45 is set to a medium amount, and the mist injection nozzle. 43 is controlled so that only gas is injected. In the case of an image density (solvent amount) of “40% or more and less than 60%” in FIG. 22, the gas injection amount from the gas injection nozzle 45 is made small, and only the gas is injected from the mist injection nozzle 43. Control to do. In the case of an image density (solvent amount) of “20% to less than 40%” in FIG. 22, the amount of gas injection from the gas injection nozzle 45 is set to a small amount, and mist injection is performed from the mist injection nozzle 43. To control.

  Further, when an image (including a white background image) having a lower density than the halftone image is formed on the intermediate transfer body 12 (in the case of an image density (solvent amount) of “0% to less than 20%” in FIG. 22). In this case, the amount of gas injected from the gas injection nozzle 45 is controlled to be small and the mist injection from the mist injection nozzle 43 is controlled. In this way, when an image with a low density (including a white background image) is formed, the amount of liquid on the intermediate transfer body 12 is small, so a small amount of gas is ejected from the gas ejection nozzle 45 to reduce the solvent removal amount. The liquid is supplied from the mist injection nozzle 43 by performing mist injection.

  As described above, by controlling the gas injection amount from the gas injection nozzle 45, the gas injection amount from the mist injection nozzle 43, or the mist injection amount in accordance with the liquid amount on the intermediate transfer body 12, Regardless of the amount of liquid on the intermediate transfer member 12, stable solvent removal can be performed.

  The solvent removal roller 42 may be driven by energizing the intermediate transfer body 12, but if connected to a counter roller or the like with a gear having an adjusted reduction ratio, the followability to the intermediate transfer body 12 is improved. preferable.

  Further, the solvent removal roller 42 (particularly, the outer peripheral surface) is heated by a roller heating unit (reference numeral 354 in FIG. 26) such as a heater, and the boiling point of the solvent after the treatment liquid and ink react, specifically, the main component. If the heating temperature is controlled within a range below the boiling point of certain water and below the melting temperature of the polymer fine particles contained in the coagulation treatment agent or ink, dissolution of the coagulation treatment agent layer and releasability of the solvent removal roller 42 can be improved. Thus, the effect of solvent removal is further increased.

  Specifically, when the polymer fine particles contained in the aggregating agent or ink are non-crystalline polymer fine particles, the heating temperature is adjusted within the range of the glass transition point or lower (for example, 50 ° C. or lower for acrylics). Is preferred. When the polymer fine particles contained in the aggregating agent or ink are crystalline polymer fine particles, the heating temperature is controlled within the melting point or lower (for example, 110 ° C. or lower for ethylene and 70 ° C. or lower for WAX). It is preferable to do this.

  As shown in FIG. 23, the stretching roller 34B may be moved in the rotational direction of the solvent removal roller 42. Thereby, the winding amount (contact length) of the intermediate transfer body 12 around the solvent removal roller 42 can be increased by the winding angle θ, and the effect of removing the solvent can be obtained more reliably.

[Explanation of control system]
FIG. 24 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 270, a system controller 272, a memory 274, a motor driver 276, a heater driver 278, a cooler control unit 279, a print control unit 280, an image buffer memory 282, a head driver 284, and the like.

  The communication interface 270 is an interface unit that receives image data sent from the host computer 286. As the communication interface 270, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. The image data sent from the host computer 286 is taken into the inkjet recording apparatus 10 via the communication interface 270 and temporarily stored in the memory 274.

  The memory 274 is a storage unit that temporarily stores an image input via the communication interface 270, and data is read and written through the system controller 272. The memory 274 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 272 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 272 controls the communication interface 270, the memory 274, the motor driver 276, the heater driver 278, the cooler control unit 279, and the like to control communication with the host computer 286, read / write control of the memory 274, etc. And a control signal for controlling the motor 288 and the heater 289 of the transport system is generated.

  The ROM 275 stores programs executed by the CPU of the system controller 272 and various data necessary for control. The ROM 275 may be a non-rewritable storage unit or a rewritable storage unit such as an EEPROM. The memory 274 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 276 is a driver that drives the motor 288 in accordance with an instruction from the system controller 272. In FIG. 24, the motors arranged in the respective units in the apparatus are represented by reference numeral 288. For example, the motor 288 shown in FIG. 24 includes a motor for driving the drive roller in the stretching rollers 34A to 34C in FIG. 1, a motor for the movement mechanism of the solvent removal roller 42, a transfer roller 36, and a pressure roller. 48 motors of moving mechanisms and the like are included.

  The heater driver 278 shown in FIG. 24 is a driver that drives the heater 289 in accordance with an instruction from the system controller 272. In FIG. 24, a plurality of heaters provided in the inkjet recording apparatus 10 are represented by reference numeral 289. For example, the heater 289 shown in FIG. 24 includes the heater of the heating unit 18 shown in FIG. 1, the preheater 46, the heater 65 of the first cleaning unit 30, and the temperature control of the treatment liquid application unit 16 shown in FIG. The temperature controller 183, the temperature controller 197, and the like in the liquid supply system of the liquid ejecting unit 152 of FIGS. 17 and 18 are included.

  24 is a control unit that performs temperature control of the cooler 20 (see FIG. 1) in accordance with an instruction from the system controller 272.

  The print control unit 280 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the memory 274 under the control of the system controller 272, and the generated print It is a control unit that supplies data (dot data) to the head driver 284. Necessary signal processing is performed in the print controller 280, and the ejection amount and ejection timing of the ink droplets of the head 80 are controlled via the head driver 284 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 280 includes an image buffer memory 282, and image data, parameters, and other data are temporarily stored in the image buffer memory 282 when image data is processed in the print control unit 280. In FIG. 24, the image buffer memory 282 is shown in a mode associated with the print control unit 280, but it can also be used as the memory 274. Also possible is an aspect in which the print control unit 280 and the system controller 272 are integrated to form a single processor.

  An overview of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 270 and stored in the memory 274. At this stage, for example, RGB image data is stored in the memory 274.

  In the ink jet recording apparatus 10, a pseudo continuous tone image is formed by changing the droplet ejection density and dot size of fine dots with ink (coloring material) to the human eye. It is necessary to convert to a dot pattern that reproduces the gradation (shading of the image) as faithfully as possible. Therefore, the original image (RGB) data stored in the memory 274 is sent to the print control unit 280 via the system controller 272, and the print control unit 280 performs halftoning processing using a threshold matrix, an error diffusion method, or the like. Is converted into dot data for each ink color.

  That is, the print control unit 280 performs processing for converting the input RGB image data into dot data of four colors K, C, M, and Y. Thus, the dot data generated by the print control unit 280 is stored in the image buffer memory 282. Note that the primary image formed on the intermediate transfer body 12 must be a mirror image of the secondary image finally formed on the recording medium 14 in consideration of inversion at the time of transfer. That is, the drive signals supplied to the heads 22Y, 22M, 22C, and 22K are drive signals corresponding to the mirror image, and the print control unit 280 needs to invert the input image.

  The head driver 284 outputs a drive signal for driving the actuator 88 corresponding to each nozzle 81 of the head 80 based on the print data (that is, dot data stored in the image buffer memory 282) given from the print control unit 280. Output. The head driver 284 may include a feedback control system for keeping the head driving conditions constant.

  When the drive signal output from the head driver 284 is applied to the head 80, ink is ejected from the corresponding nozzle 81. An image (primary image) is formed on the intermediate transfer member 12 by controlling the ink discharge from the head 80 while conveying the intermediate transfer member 12 at a predetermined speed.

  Further, the system controller 272 controls the transfer control unit 292 and the treatment liquid application control unit 294, and controls the operations of the solvent removal unit 24, the first cleaning unit 30, and the second cleaning unit 32 described with reference to FIG. To do.

  The transfer control unit 292 shown in FIG. 24 performs temperature control and nip pressure control of the transfer roller 36 and the pressure roller 48 (see FIG. 1) of the transfer unit 26. Optimum values (control target values) of nip pressure and transfer temperature are obtained in advance for each type of recording medium 14 and ink type, and are stored in a predetermined memory (for example, ROM 275) as a data table. When the system controller 272 acquires information on the recording medium 14 to be used and information on the ink to be used by input by an operator, automatic reading from a predetermined sensor, or the like, the transfer roller 36 and the pressure roller 48 are referred to the data table. Temperature and nip pressure are controlled.

  The processing liquid application control unit 294 illustrated in FIG. 24 controls the operation of the processing liquid application unit 16 in accordance with an instruction from the system controller 272. When the liquid coating apparatus 100 described with reference to FIG. 8 is applied to the treatment liquid coating unit 16, as shown in FIG. 24, the contact / separation mechanism driving unit for the drain valve 302, the liquid feed pump 104, and the gravure roller 38 The processing liquid application control unit 294 controls the 304, the gravure roller rotation driving unit 306, the replacement fluid ejection valve 308, and the like.

  The drainage valve 302 includes the processing liquid discharge valve 126 and the removal liquid discharge valve 132 described with reference to FIG. Further, the replacement fluid injection valve 308 in FIG. 24 corresponds to an electromagnetic valve that performs injection (on) / non-injection (off) of the replacement fluid injection unit 114 described in FIG.

  The system controller 272 determines the image forming area and the non-image forming area on the intermediate transfer body 12 based on the image data to be printed, and does not apply the processing liquid to the portion corresponding to the non-image forming area. Further, the contact / separation mechanism driving unit 304 is controlled. As a result, the processing liquid is selectively applied to the portion corresponding to the image forming area of the intermediate transfer body 12. In the case of this example, the combination of the system controller 272 and the treatment liquid application control unit 294 functions as “replacement fluid ejection control means”.

  Further, in order to remove residues collected in the cells of the gravure roller 38 during maintenance cleaning of the intermediate transfer body 12 during non-image formation such as when the ink jet recording apparatus is started up, during standby, or during batch processing, The processing liquid application controller 294 controls the replacement fluid ejection valve 308 to be turned on so that the replacement fluid is ejected onto the outer peripheral surface of the gravure roller 38.

  Further, at the time of maintenance cleaning of the intermediate transfer body 12, the system controller 272 instructs the first cleaning unit control unit 320 to control the blade 64 to be separated from the intermediate transfer body 12.

  At the same time, the system controller 272 pushes the intermediate transfer body 12 while the gravure roller 38 is in contact with the intermediate transfer body 12 by the contact / separation mechanism driving section 304 with respect to the processing liquid application control section 294. May be instructed to be larger than that during image formation. Alternatively, the system controller 272 may control the stretching roller 34C (see FIG. 1) so that the tension of the intermediate transfer body 12 is increased in a state where the gravure roller 38 is in contact with the intermediate transfer body 12.

  When the liquid application apparatus 150 described with reference to FIG. 14 is applied to the treatment liquid application unit 16, instead of the configuration of the drain valve 302 and the liquid feed pump 104 in FIG. 24, as shown in FIG. The precision regulator 310 and the liquid injection valve 312 are controlled. The variable precision regulator 310 shown here is a means for changing the injection pressure from the liquid injection unit 152 in FIG. 14, and corresponds to that indicated by reference numeral 188 in the example of FIG.

  Further, the liquid ejection valve 312 shown in FIG. 25 is a means for switching between ejection (on) / non-ejection (off) from the liquid ejection section 152 in FIG. 14, and is denoted by reference numeral 182 in the example of FIG. Applicable to solenoid valves.

  Note that the gravure roller 38 and the like can be cleaned if the processing liquid application controller 294 controls the liquid ejecting unit 152 to eject a cleaning liquid having a component different from the processing liquid during non-image formation.

  FIG. 26 is a block diagram illustrating a configuration of the solvent removal control unit 340. The solvent removal control unit 340 shown in FIG. 26 controls the operation of the solvent removal unit 24 in accordance with an instruction from the system controller 272. As shown in FIG. 26, the variable precision regulator 342, the temperature controller 343, the mist injection valve 344, the contact / separation mechanism drive unit 346 of the solvent removal roller 42, the solvent removal roller rotation drive unit 348, the gas injection valve 350, the temperature control The device 351, the variable precision regulator 352, and the like are controlled by the solvent removal control unit 340.

  The mist injection valve 344 in FIG. 26 corresponds to the electromagnetic valve 222 or the like that performs injection (on) / non-injection (off) of the nozzle body 220 described in FIG.

  The system controller 272 controls on / off of the mist injection valve 344 in order to adjust the amount of liquid ejected to the solvent removal roller 42 based on image data to be printed. As a result, the amount of liquid on the intermediate transfer body 12 is adjusted.

  The variable precision regulator 342 is a means for varying the injection pressure from the mist injection nozzle 43 in FIGS. 20 and 23, and corresponds to the reference numeral 234 in the example of FIG.

  The gas injection valve 350 is means for switching injection (on) / non-injection (off) from the gas injection nozzle 45 in FIGS. 20 and 23, and is denoted by reference numeral 212 in the example of FIG. The indicated solenoid valve is applicable.

  Further, the variable precision regulator 352 is a means for varying the injection pressure from the gas injection nozzle 45 in FIGS. 20 and 23, and corresponds to the reference numeral 216 in the example of FIG.

  The temperature controller 343 is means for heating the liquid constituting the mist ejected from the mist ejection valve 344, and corresponds to the one indicated by the reference numeral 224 in the example of FIG.

  Further, the temperature controller 351 is a means for heating the gas injected from the gas injection valve 350, and corresponds to what is indicated by reference numeral 213 in the example of FIG.

  The roller heating unit 354 is a means for heating the solvent removal roller 42 (particularly its outer peripheral surface).

  Further, during maintenance cleaning of the intermediate transfer body 12 during non-image formation, the solvent removal control unit 340 controls the contact / separation mechanism driving unit 346 in accordance with an instruction from the system controller 272, and the solvent removal roller 42. May be brought into contact with the intermediate transfer body 12. Thereby, the solvent removal roller 42 can also be cleaned.

(Image forming method)
An image forming method of the inkjet recording apparatus 10 according to the first embodiment having the above configuration will be described. FIG. 27 is a flowchart showing an operation sequence of image formation by the inkjet recording apparatus 10.

  As shown in FIG. 27, the treatment liquid application unit 16 applies a treatment liquid (aggregation treatment agent) as an undercoat liquid to the intermediate transfer body 12 (treatment liquid application step, step S1). Specifically, in the present embodiment, the processing liquid T-2 is used as the processing liquid. The treatment liquid T-2 has a low viscosity of less than 15 mPa · s at the time of preparation, but is then left to stand for 12 hours or more, preferably 1 day or more after the preparation at a temperature of 20 ° C. to 30 ° C. (Prepared and stored) to thicken.

  Then, the thickened processing liquid is stored in the processing liquid supply tank 102 of the processing liquid application unit 16. Thereafter, the temperature of the treatment liquid is set to 15 to 40 ° C. by the temperature controller 122, and the viscosity is set to 15 mPa · s or more and 60 mPa · s or less (dotted line region A in FIG. 7). Then, the processing liquid T-2 having a viscosity of 15 mPa · s or more and 60 mPa · s or less is supplied to the processing liquid container 40 by driving the liquid feeding pump 104, and 1 μm is applied to the intermediate transfer body 12 using the gravure roller 38. The film is applied with a film thickness of 15 μm or less. As a result, the treatment liquid can be uniformly applied to the intermediate transfer body 12.

  More preferably, the treatment liquid T-2 is applied to the intermediate transfer body 12 with a film thickness of 2 μm or more and 10 μm or less.

  Further, since the treatment liquid T-2 has a low viscosity at the time of liquid preparation, work suitability such as filtration is improved.

  The treatment liquid T-2 having a viscosity of 15 mPa · s or more and increased to 60 mPa · s can form a homogeneous thin film without causing liquid flow even on the low-surface energy intermediate transfer body 12. Further, when the processing liquid T-2 is sprayed and applied to the gravure roller 38 (see FIG. 14), or when the processing liquid T-2 is removed by spraying the air by the replacement fluid spraying unit 114, liquid scattering can also be reduced. The treatment liquid T-2 is a polymer resin having a particle size of 0.5 μm or more and 5 μm or less for the purpose of further stabilizing coating unevenness, improving agglomerate fixing property during ink droplet ejection, and releasing property during transfer. It is desirable to contain (fine particles) in an amount of 1 wt% to 5 wt%. In addition to the polymer resin, it is preferable to add microcapsules encapsulating higher alcohols or esters into a polyvinyl alcohol film agent because it is destroyed by heat or pressure during transfer and the releasability is further improved.

  The treated liquid T-2 that has been prepared and stored may be temporarily heated by the temperature controller 122 in the range of 30 ° C. or more and 40 ° C. or less, and then the temperature may be lowered and applied to the intermediate transfer body 12. The viscosity of the treatment liquid T-2 once heated in the range of 30 ° C. to 40 ° C. is stabilized within the range of 15 mPa · s to 30 mPa · s even when the temperature is lowered. Application to the transfer body 12 is more homogeneously stabilized. In addition, it is possible to suppress moisture evaporation of the treatment liquid T-2 as compared with the case where the coating is performed while always heating. In addition, when raising the temperature inside the apparatus, it is more effective to adjust the temperature of the heated treatment liquid T-2 to be 20 ° C. or higher and 30 ° C. or lower.

  Next, the applied processing liquid is heated by the heating unit 18 and then cooled by the cooler 20 (heating and cooling step, step S2). Specifically, the temperature of the processing liquid T-2 is temporarily increased by the heating unit 18 (heater of 50 ° C. or more and 100 ° C. or less) to temporarily reduce the viscosity, and the viscosity is temporarily reduced to 0.5 μm or more and 3 μm or less. An aggregating agent layer having a thickness of 5 is formed. Then, the temperature of the aggregation treatment agent layer is cooled to 10 ° C. or higher and 50 ° C. or lower (dotted line region B in FIG. 7), more preferably 35 ° C. or higher and 45 ° C. or lower by the cooler 20.

  Next, each color (YMCK) pigment ink is ejected from each head 22Y, 22M, 22C, 22K of the printing unit 22 in accordance with an image signal to perform droplet ejection on the aggregation treatment agent layer (ink droplet ejection process, Step S3). Specifically, a primary image is formed on the intermediate transfer body 12 with an ink ejection volume of about 2 pl and a recording density of 1200 dpi in both the main scanning and sub-scanning directions. The ink can contain a polymer resin (fine particles) having film-forming properties, and the abrasion resistance and storage stability are improved by the transfer process and the fixing process.

  Here, in step S2, the temperature of the treatment liquid T-2 is temporarily increased by the heating unit 18 (heater of 50 ° C. or more and 100 ° C. or less) to temporarily reduce the viscosity, and the cooler 20 causes aggregation. The temperature of the treatment agent layer is 10 ° C. or more and 50 ° C. or less (dotted line region B in FIG. 7), more preferably 35 ° C. or more and 45 ° C. or less. 2 has a viscosity of less than 15 mPa · s. Therefore, the ink aggregation reaction is promoted, and the speed of ink aggregation is increased.

  Further, since the temperature of the aggregation treatment agent layer is cooled to 10 ° C. or more and 50 ° C. or less, more preferably 35 ° C. or more and 45 ° C. or less, drying of the nozzles 81 of the heads 22Y, 22M, 22C, and 22K is prevented. In addition, the discharge characteristics can be stabilized.

  Next, the solvent (residual solvent) component separated from the pigment aggregate is removed from the intermediate transfer body 12 by the solvent removal roller 42 of the solvent removal unit 24 (solvent removal step, step S4). Here, the aggregation treatment agent layer formed by the treatment liquid T-2 is reduced in viscosity even after being dried by the heating unit 18 and then cooled by the cooler 20, so that the ink aggregation reaction is performed as described above. Is accelerated, and high-speed processing for removing the solvent component becomes possible.

  Next, the primary image formed on the intermediate transfer body 12 is transferred to the recording medium 14 (transfer process, step S5). Specifically, the intermediate transfer member 12 is preheated to 90 ° C. or more and 130 ° C. or less by the preheater 46, and then the formed image is transferred from the intermediate transfer member 12 to the recording medium 14 by the transfer unit 26. A preferable nip pressure during transfer is 1.5 to 2.0 MPa, and a roller temperature of the transfer roller 36 is 80 ° C. or higher and 120 ° C. or lower.

  Note that it is preferable that the recording medium 14 is preheated to 70 ° C. or more and 100 ° C. or less in the paper feeding unit 28 because transferability is further improved. Further, if polymer particles or microcapsules are added to the treatment liquid T-2, release is promoted and transferability is improved.

  Next, the recording medium 14 is separated from the intermediate transfer member 12 by the peeling claw 56 and discharged outside the apparatus (discharge step, step 6).

  Next, the intermediate transfer body 12 is cleaned by the first cleaning unit 30 (first cleaning unit step, step S7). Specifically, the first cleaning unit 30 performs cleaning by applying a cleaning liquid to the intermediate transfer body 12 heated to 60 ° C. or more and 110 ° C. or less by the heater 65.

  In this embodiment, the processing liquid T-2 is used as the processing liquid, and the cleaning liquid is reduced in viscosity (less than 5 mPa · s) by the action of the surfactant contained in the aggregation processing agent remaining on the intermediate transfer body 12. Since the surface tension is lowered, cleaning is performed at high speed and reliably. Further, when the treatment liquid T-2 contains polyethylene as polymer particles, it has appropriate adhesion to the intermediate transfer body 12, so that the cleaning performance of the intermediate transfer body 12 is improved.

  The recording medium 14 peeled off by the peeling claw 56 is further improved in abrasion resistance and storability by passing through a fixing step (not shown). In this case, the heating temperature is preferably 100 ° C. or more and 130 ° C. or less, and the applied pressure is preferably 2.5 to 3.0 MPa, and is optimized according to the temperature characteristics (film formation temperature: MFT) of the added polymer resin.

  Table 6 shows the experimental results for verifying the effect of the treatment liquid T-2 in each step of the image forming method as described above. In Table 6, the case where the treatment liquid T-2 is not applied to the intermediate transfer body 12 and the case where the treatment liquid T-2 is applied to the intermediate transfer body 12 are verified, and the treatment liquid T-2 is further applied to the intermediate transfer body 12. When giving, the experimental result verified for every content of the content of the process liquid T-2 is shown.

  During non-image formation, the processing liquid T-2 is temporarily heated to 60 ° C. or higher by the temperature controller 122 and then the temperature is lowered, and the processing liquid T− is applied to the intermediate transfer body 12 by the processing liquid coating unit 16. 2 is applied, the treatment liquid T-2 once heated to a high temperature is reduced in viscosity to less than 15 mPa · s even when the temperature is lowered. Therefore, the maintenance of the gravure roller 38 and the blade 64 after the work is completed (low viscosity liquid). Cleaning) can be performed effectively. Moreover, since heating is temporary, moisture evaporation during maintenance can also be reduced. In addition, since it is not necessary to always put a high-temperature heater, power consumption can be suppressed and energy saving can be achieved. Further, it is more effective if the processing liquid T-2 is removed from the cell of the gravure roller 38 by the replacement fluid ejecting unit 114. In addition, since the processing liquid T-2 having a reduced viscosity can be circulated, maintenance of the supply and recovery system (low-viscous liquid cleaning) is also possible.

  In the first embodiment described above, an example in which an aggregating treatment agent (treatment liquid) is applied and then dried to form an aggregating agent layer and ink is ejected on the ink is shown. An embodiment in which an aggregating agent is applied after the dropping is also possible. Hereinafter, this aspect will be described as a second embodiment.

[Second Embodiment]
FIG. 28 is a configuration diagram of an ink jet recording apparatus 700 according to the second embodiment. In FIG. 28, elements that are the same as or similar to the example described in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  In the ink jet recording apparatus 700 shown in FIG. 28, the undercoat liquid applied by the treatment liquid application unit 16 is different from the example of FIG. 1 described above, and the heating unit 18 and the cooler 20 in FIG. Instead, a configuration in which a liquid discharge head (hereinafter referred to as “aggregated liquid head”) 702 for applying an aggregating treatment liquid (image forming liquid) 702 is provided at the subsequent stage of the printing unit 22.

  That is, the ink jet recording apparatus 700 shown in this example forms a first processing liquid layer with an undercoat liquid (hereinafter also referred to as “first processing liquid”) on the intermediate transfer body 12, and ink is contained in the first processing liquid layer. After the droplets are ejected, an aggregating treatment liquid (hereinafter also referred to as “second treatment liquid”) having a function of aggregating the ink droplets corresponding to the ink droplets in the first treatment liquid layer is ejected. A three-component image forming method is applied in which the colorant (pigment) in the ink is aggregated by dropping to form an ink aggregate.

  The first treatment liquid applied by the treatment liquid application unit 16 of the ink jet recording apparatus 700 is a liquid that does not have a function of aggregating ink droplets even when it comes into contact with the ink droplets. It has the time dependency of the viscosity like the treatment liquid T-2 as shown in FIG. 7 by adding the agent, and has a characteristic (hysteresis) that changes in the viscosity characteristic with respect to the temperature with the passage of time. Liquid. And it is possible to use such a 1st process liquid by thickening to 15 mPa * s or more and 60 mPa * s or less by liquid storage. Table 7 shows an example of adjusting the first treatment liquid.

  The aggregation processing liquid (second processing liquid) discharged from the aggregation liquid head 702 aggregates the pigment (coloring material) and polymer fine particles contained in the ink by changing the pH of the ink, thereby generating an ink aggregate. A treatment liquid having a function of causing the above is preferable.

  The aggregation treatment liquid storage / loading unit 704 shown in FIG. 28 includes a tank that stores the second treatment liquid supplied to the aggregation liquid head 702. The tank communicates with the aggregate liquid head 702 through a required flow path.

  As the coagulating liquid head 702 of this example, one having the same configuration as the head arranged in the printing unit 22 is applied. The aggregating liquid head 702 only needs to be capable of applying the aggregating treatment liquid to the intermediate transfer body 12 in a non-contact manner, and the droplet ejection density (resolution) is higher than that of the ink heads 22Y, 22M, 22C, and 22K. A head having a structure in which a drop is applied may be applied, or a method other than the inkjet method such as a spray method may be applied.

  As components of the second treatment liquid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, orthophosphoric acid Pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof preferable. Moreover, you may use the processing liquid shown in Table 1 and Table 2.

  Further, as a preferred example of the second treatment liquid, a treatment liquid to which a polyvalent metal salt or polyallylamine is added can be mentioned. These compounds may be used alone or in combination of two or more.

  The second treatment liquid preferably has a pH of 1 to 6, more preferably 2 to 5, and particularly preferably 3 to 5 from the viewpoint of pH aggregation performance with the ink.

  The addition amount of the component for aggregating the pigment and polymer fine particles of the ink in the second treatment liquid is preferably 0.01% by weight or more and 20% by weight or less with respect to the total weight of the liquid. When the amount is 0.01% by weight or less, the concentration diffusion does not proceed sufficiently when the second processing liquid and the ink are in contact with each other, and the aggregation action due to the pH change may not occur sufficiently. Further, if it is 20% by weight or more, there is a concern that the discharge performance from the ink jet head deteriorates (for example, occurrence of discharge abnormality).

  The second treatment liquid preferably contains water and other additive-soluble organic solvents for the purpose of preventing clogging of the nozzles of the discharge head (702) due to drying. Such water and other additive-soluble organic solvents include wetting agents and penetrants. These solvents can be used alone or in combination with water and other additives.

  The content of water and other additive-soluble organic solvents is preferably 60% by weight or less based on the total weight of the second treatment liquid. When the amount is more than 60% by weight or more, the viscosity of the treatment liquid increases, and the dischargeability from the inkjet head may deteriorate.

  The second processing liquid may further contain a resin component in order to improve fixability and abrasion resistance. The resin component may be any resin component that does not impair the ejection properties from the head when the treatment liquid is ejected by the ink jet method and has storage stability, and water-soluble resins and resin emulsions can be used freely.

  Examples of the resin component include acrylic, urethane, polyester, vinyl, and styrene. In order to sufficiently develop the function of improving the fixing property, it is necessary to add a relatively high polymer to a high concentration of 1% by weight to 20% by weight. However, if it is attempted to dissolve the above material in a liquid and add it, the viscosity becomes high, and the discharge property is lowered. In order to add an appropriate material at a high concentration and suppress an increase in viscosity, a means of adding as a latex is effective. Latex materials include alkyl acrylate copolymers, carboxy-modified SBR (styrene-butadiene latex), SIR (styrene-isoprene) latex, MBR (methyl methacrylate-butadiene latex), NBR (acrylonitrile-butadiene latex), and the like. Conceivable.

  The glass transition temperature Tg of the latex is a value that has a strong influence upon fixing in the process, and is preferably 50 ° C. or higher and 120 ° C. or lower in order to achieve both stability at room temperature storage and transferability after heating. Further, the minimum film-forming temperature MFT is a value that has a strong influence upon fixing in the process, and is 100 ° C. or lower, more preferably 50 ° C. or lower in order to obtain sufficient fixing at a low temperature.

  A mode in which the second treatment liquid contains polymer fine particles having a polarity opposite to that of the ink and is further aggregated with the pigment and the polymer fine particles in the ink is also preferable. Further, the second processing liquid contains a curing agent corresponding to the polymer fine particle component contained in the ink, and after the ink and the second processing liquid contact, the resin emulsion in the ink component aggregates and crosslinks or polymerizes. Thus, the cohesiveness may be increased.

  The second treatment liquid may contain a surfactant. Examples of surfactants include fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate ester salts, naphthalene sulfonate formalin condensates, Anionic surfactants such as oxyethylene alkyl sulfate esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines Nonionic surfactants such as glycerin fatty acid ester and oxyethyleneoxypropylene block copolymer are preferred.

  Further, SURFYNOLS (AirProducts & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred. Furthermore, those listed as surfactants on pages (37) to (38) of JP-A-59-157636, Research Disclosure No. Those listed as surfactants in 308119 (1989) can be used as the surfactant in the second treatment liquid.

  Further, fluorine (fluorinated alkyl type) and silicon type surfactants as described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are used. Is also possible. These surface tension adjusting agents can also be used as antifoaming agents, and fluorine-based, silicon-based compounds, chelating agents represented by EDTA, and the like can also be used.

  When the above-mentioned surfactant is contained in the second processing liquid, it is effective to lower the surface tension of the second processing liquid and increase the wettability on the intermediate transfer member. The surface tension of the second treatment liquid is preferably 10 to 50 mN / m. In application by the ink jet method, the surface tension of the second treatment liquid is 15 from the viewpoint of droplet formation and discharge performance. More preferably, it is -45mN / m.

  The viscosity of the second treatment liquid is preferably 1.0 to 20.0 cP from the viewpoint of application by an inkjet method. In addition, you may add a pH buffer agent, antioxidant, an antifungal agent, a viscosity modifier, a electrically conductive agent, an ultraviolet-ray, an absorber, etc. to a 2nd process liquid.

  FIG. 29 is a block diagram of the ink jet recording apparatus 700 shown in FIG. In FIG. 29, elements that are the same as or similar to those in the example shown in FIG. 24 are given the same reference numerals, and descriptions thereof are omitted.

  The ink jet recording apparatus 700 shown in FIG. 29 includes an aggregating liquid head 702 as a means for applying an aggregating treatment liquid (second treatment liquid) and a head driver 708 for driving the aggregating liquid head 702. The head driver 708 generates a drive signal to be applied to the actuator 88 (see FIG. 5) of the aggregate liquid head 702 based on the image data given from the print control unit 280, and applies the drive signal to the actuator 88. A drive circuit for driving the actuator 58 is included. As described above, a mode in which the aggregation liquid is ejected in accordance with the image data and the aggregation processing liquid is selectively ejected to the position where the ink is ejected by the printing unit 22 is a preferable aspect. A mode of applying uniformly using a spray nozzle is also possible.

  In place of the treatment liquid application unit 16 shown in FIG. 29, the configuration described in FIG. 25 can be employed.

  In each of the above-described embodiments, an endless belt is used as the intermediate transfer member. However, an embodiment using a drum-shaped intermediate transfer member is also possible. In this case, it is desirable from the viewpoint of workability and thermal controllability to use a fluorine elastomer or the like on the surface of a thin aluminum tube reinforced with ribs.

(Image forming method)
An image forming method of the ink jet recording apparatus 700 of the second embodiment having the above configuration will be described. FIG. 30 is a flowchart showing an operation sequence of image formation by the ink jet recording apparatus 700.

  As shown in FIG. 30, the image forming method of the ink jet recording apparatus 700 according to the second embodiment is compared with the image forming method of the ink jet recording apparatus 10 according to the first embodiment. It differs in that it has a first treatment liquid application step (step S11) instead of S1) and a second treatment liquid application step (step S14) after the ink droplet ejection step (step S13).

  In the first treatment liquid application step (step S11), the first treatment liquid is applied to the intermediate transfer body 12 by the treatment liquid application unit 16 with a thickness of 3 μm or more and 10 μm or less. As a 1st process liquid, the process liquid which has time dependence in the viscosity characteristic with respect to temperature as shown in FIG. 7 is used, The said process liquid is thickened by preparation storage, 15 mPa * s or more and 60 mPa * s or less It is applied to the intermediate transfer body 12 in the state of the viscosity.

  In the second treatment liquid application step (step S14), the second treatment liquid is ejected in correspondence with the ink droplets in the first treatment liquid layer.

  As described above, according to the image forming methods of the first and second embodiments of the present invention, the following operational effects can be obtained.

  (1) By using a treatment liquid containing a surfactant that increases in viscosity over time and controlling the treatment liquid to an appropriate viscosity, the intermediate transfer body 12 (in a direct drawing type inkjet recording apparatus, Even if the recording medium has liquid repellency, it is not necessary to perform surface modification such as plasma treatment on the intermediate transfer body 12 before application of the processing liquid, and the processing liquid is applied to the intermediate transfer body 12. Can be applied uniformly. Further, when applying to the intermediate transfer body 12, a uniform application can be achieved by setting the treatment liquid to an appropriate viscosity, and liquid scattering is also reduced. In addition, when the treatment liquid is prepared, the workability such as filtration is improved by keeping the treatment liquid low in viscosity.

  (2) Although the viscosity of the treatment liquid is lowered by heating, the viscosity at the time of subsequent cooling is lower than that before heating. Therefore, if the intermediate transfer body 12 is heated and then cooled before ink ejection, the ink is ejected. The treatment liquid is reduced in viscosity, and ink aggregation is accelerated. Further, as in the second embodiment, in the post-aggregation method in which the aggregation processing liquid (image forming liquid) is applied to the subsequent stage of the printing unit 22, it is possible to secure the ink droplet spreading rate. Furthermore, since the temperature of the intermediate transfer body 12 before ink ejection is low, it is possible to ensure nozzle drying prevention and ejection operation stability.

  (3) Since the treatment liquid has a characteristic of becoming extremely low viscosity at high temperature, if the intermediate transfer body 12 is heated to high temperature after ink ejection, the intermediate transfer type ink jet recording apparatuses 10 and 700 of the first and second embodiments are used. While the releasability at the time of transfer and the cleanability of the intermediate transfer body 12 are improved, the direct drawing type ink jet recording apparatus can promote the penetration of the high boiling point solvent into the recording medium by drying and heating the ink.

  (4) Since the treatment liquid contains polyethylene (PE) having a particle diameter of 0.5 μm or more and 5 μm or less as polymer particles, the coating property, the color material fixing property, and the transfer property are further improved by the repellency preventing effect. Moreover, the particle | grains below micrometer have a favorable dispersibility, and image visibility becomes low. Furthermore, since polyethylene has low adhesion, it is possible to ensure cleaning properties.

  (5) Since the treatment liquid contains microcapsules of particles having a heat-sensitive or pressure-sensitive particle diameter of 0.5 μm or more and 5 μm or less, in the intermediate transfer type ink jet recording apparatuses 10 and 700 of the first and second embodiments. In the direct drawing type ink jet recording apparatus, voids are formed while releasing a releasing agent at the time of transfer, so that a high-boiling point ink penetrates the recording medium and image stability is improved. . Particles of μm or less have good dispersibility and can be broken by heat or pressure during transfer or fixing.

  (6) An image is formed by a process of coating, heating / cooling, drawing, heating, transfer / fixing, and the processing liquids (1) to (5) are used. High-speed and high-quality image formation can be performed by the intermediate transfer type inkjet recording devices 10 and 700 and the direct drawing type inkjet recording device. In the intermediate transfer type inkjet recording apparatuses 10 and 700 of the first and second embodiments, the cleaning property of the intermediate transfer body 12 is also improved due to the effect of the heated aggregation treatment agent residual component.

  The image forming method and the image forming apparatus of the present invention have been described in detail above. However, the present invention is not limited to the above examples, and various improvements and modifications are made without departing from the gist of the present invention. Of course it is also good.

  For example, the present invention can be applied to a direct drawing type ink jet recording apparatus as an image forming apparatus.

1 is an overall configuration diagram of an ink jet recording apparatus according to a first embodiment. Plan view of the main part around the printing unit Plane perspective view showing the internal structure of the head Plan view showing another configuration example of the head Sectional drawing which follows the 5-5 line in FIG. Plan view showing an example of nozzle arrangement of the head Evaluation result diagram of viscosity characteristics with respect to temperature of treatment liquid T-1 and treatment liquid T-2 The block diagram which shows the 1st example of the liquid application apparatus applied to a process liquid application part The figure which shows the example of the cell shape formed in the surface of a gravure roller, and the groove shape formed in the surface of a spiral roller A diagram showing visibility from the relationship between the number of cell lines and the density difference ΔD. Line spray configuration diagram showing an example of an injection member applied to a gas injection nozzle Diagram showing an example of line spray usage Illustration of flat spray nozzle The block diagram which shows the 2nd example of the liquid application apparatus applied to a process liquid application part Graph showing liquid volume distribution of liquid spray pattern by flat spray Explanatory drawing schematically showing the relationship between the liquid ejecting unit and the replacement fluid ejecting unit Configuration example of liquid supply system when gas (air) is used as replacement fluid Other configuration examples of the liquid supply system of the treatment liquid ejection unit Explanatory drawing which shows the example of control of the application range of the process liquid with respect to an intermediate transfer body Enlarged view of the solvent removal section Explanatory drawing which shows the structural example of the liquid supply system of a solvent removal part The figure which shows the example of control regarding injection of a gas injection nozzle and a mist injection nozzle The figure which shows the example arrange | positioned by moving the tension roller to the rotation direction of a solvent removal roller 1 is a block diagram showing a system configuration of an ink jet recording apparatus according to a first embodiment. Main part block diagram which shows the system configuration at the time of applying the liquid coating device demonstrated in FIG. Block diagram showing the configuration of the solvent removal control unit The flowchart figure which shows the operation | movement sequence of the image formation by an inkjet recording device. Overall configuration diagram of an ink jet recording apparatus according to a second embodiment FIG. 2 is a block diagram showing a system configuration of an ink jet recording apparatus according to a second embodiment. The flowchart figure which shows the operation | movement sequence of the image formation by an inkjet recording device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,700 ... Inkjet recording device, 12 ... Intermediate transfer body, 14 ... Recording medium, 16 ... Treatment liquid application part, 18 ... Heating part, 20 ... Cooler, 22 ... Printing part, 22Y, 22M, 22C, 22K ... Head , 26 ... transfer section, 30 ... first cleaning section, 32 ... second cleaning section, 36 ... transfer roller, 38 ... gravure roller, 42 ... solvent removal roller, 43 ... mist injection nozzle, 44 ... dirt detection section, 45 ... Gas injection nozzle 48 ... Pressure roller 60 ... Cleaning liquid injection part 62 ... Rotating brush 64 ... Blade 66 ... Adhesion roller 68 ... Adhesion roller 70 ... Cleaning web (or adhesion belt) 81 ... Nozzle 82 ... Pressure chamber, 88 ... Actuator, 100, 150 ... Liquid applicator, 110 ... Squeegee blade, 152 ... Liquid ejector, 272 ... System controller Over La, 294 ... treatment liquid application control unit, 702 ... aggregating liquid head

Claims (17)

In an image forming method comprising: a treatment liquid application step for applying a treatment liquid to an application medium; and an ink application step for applying ink to the treatment liquid applied to the application medium.
The treatment liquid has a viscosity characteristic that the viscosity after preparation increases with time, and the viscosity when applied to the application medium is higher than the viscosity during preparation;
An image forming method. The image forming method according to claim 1.
The treatment liquid has a viscosity characteristic that is lower when the temperature is lowered than when the ratio of the viscosity change amount to the temperature change amount is lower than a predetermined temperature when the temperature is raised,
An image forming method. The image forming method according to claim 1 or 2,
The treatment liquid contains 1% by weight or more and 10% by weight or less of a surfactant, has a viscosity of less than 15 mPa · s at the time of liquid preparation, and has a temperature of 15 ° C. or more and 40 ° C. before being applied to the application medium. The viscosity when the temperature is not higher than 15 ° C. is not less than 15 mPa · s and not more than 60 mPa · s, and when the temperature is not lower than 15 ° C. and not higher than 40 ° C., the viscosity is less than 15 mPa · s.
An image forming method. The image forming method according to any one of claims 1 to 3,
In the treatment liquid application step, the treatment liquid before being applied to the application medium is raised to a temperature within a range of 30 ° C. or more and 40 ° C. or less, and then applied to the application medium at the temperature or lower.
An image forming method. The image forming method according to any one of claims 1 to 4,
In the ink application step, the ink is applied to the treatment liquid having a temperature of 10 ° C. or more and 50 ° C. or less after the temperature is made higher than 50 ° C .;
An image forming method. The image forming method according to any one of claims 1 to 5,
The surfactant is a fluorine-based anionic surfactant represented by the following chemical formula 1,
An image forming method.

The image forming method according to any one of claims 1 to 6,
The treatment liquid contains polymer particles or microcapsules having a particle size of 0.5 μm or more and 5 μm or less,
An image forming method. The image forming method according to claim 7.
The polymer particles are polyethylene;
An image forming method. The image forming method according to claim 7.
The microcapsule is one in which a higher alcohol or ester is encapsulated in a polyvinyl alcohol film agent,
An image forming method. The image forming method according to any one of claims 1 to 9,
In the treatment liquid application step, applying the treatment liquid to the application medium with a thickness of 1 μm or more and 15 μm or less,
An image forming method. The image forming method according to any one of claims 1 to 10,
The medium to be applied is an intermediate transfer member in an intermediate transfer type image forming apparatus;
An image forming method. The image forming method according to claim 11.
The surface energy of the intermediate transfer member is 15 mN / m or more and 30 mN / m or less,
An image forming method. The image forming method according to claim 11 or 12,
The treatment liquid contains 5 wt% or more and 20 wt% or less of an ink flocculant;
An image forming method. The image forming method according to claim 11 or 12,
The treatment liquid does not contain an ink flocculant,
Having an aggregating agent applying step of applying an ink aggregating agent to the ink applied in the ink applying step;
An image forming method. The image forming method according to any one of claims 1 to 10,
The medium to be imparted is a recording medium in a direct drawing type image forming apparatus;
An image forming method. The image forming method according to claim 15.
The treatment liquid contains 5 wt% or more and 20 wt% or less of an ink flocculant;
An image forming method. In an image forming apparatus comprising: a treatment liquid application unit that applies a treatment liquid to an application medium; and an ink application unit that applies ink to the treatment liquid applied to the application medium.
The treatment liquid has a viscosity characteristic that the viscosity after preparation increases with time, the viscosity when applied to the application medium is higher than the viscosity during preparation,
Temperature adjusting means for adjusting the temperature of the treatment liquid;
Control means for controlling the viscosity of the processing liquid by adjusting the temperature of the processing liquid by the temperature adjusting means when applying the processing liquid to the medium to be applied by the processing liquid applying means;
An image forming apparatus comprising:

Images