JP2009083317A - Image forming method and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent irregularities in an image due to movement of a color material and development of gloss in a non-image part on a recording medium and to improve high speed transferring performance in a transfer recording method. <P>SOLUTION: The image forming method includes steps of: forming a solid or a semi-solid solution state processing agent layer comprising a processing agent containing at least one kind of solid particles on an intermediate transfer body; dripping ink formed into droplets onto a surface of the processing layer formed on the intermediate transfer body according to image data; and image transferring to a recording medium from the intermediate transfer body with a surface temperature of the intermediate transfer body less than the melting point of the solid particles, wherein the surface roughness (Ra) of the processing agent layer formed on the intermediate transfer body is higher than the particle diameter of the color material contained in the ink. <P>COPYRIGHT: (C)2009,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 and an image forming apparatus for transferring an ink image (primary image) formed on an intermediate transfer member to a recording medium.

  Conventionally, an ink image (primary image) is formed on an intermediate transfer body by ejecting ink droplets from a plurality of nozzles formed on an inkjet recording head (inkjet head), and then formed on the intermediate transfer body. There is known an ink jet recording apparatus of a system (hereinafter referred to as “transfer recording system”) for transferring the ink image to a recording medium.

  In recent years, there has been an increasing demand for higher image quality and higher speed recording for transfer recording systems, and one of the technical problems is to improve transferability from an intermediate transfer body to a recording medium.

In Patent Document 1, a slippery coating layer made of wax or lubricant is formed on an intermediate transfer member surface layer (release layer) having a release performance, and the transfer roller temperature is set to be equal to or higher than the melting point of the wax or lubricant. In addition, a technique is disclosed in which the slippery coating layer is partially melted by contact with a transfer roller at the time of transfer, and the releasability of an image formed on the intermediate transfer member is further improved.
JP 2002-316408 A

  However, in the invention described in Patent Document 1, a large amount of wax or lubricant must be applied in order to form a slippery coating layer made of wax or lubricant on the surface of the intermediate transfer member, and the entire area of the medium to be transferred A smooth layer of melted wax or lubricant adheres to both the image area and the non-image area. As a result, the non-image portion on the transferred recording medium is more glossy than necessary, and there is a problem that the texture of the obtained image is impaired.

  In addition, in a slippery layer having a low surface roughness, the color material in the image formed on the slippery coating layer made of wax or lubricant moves due to spreading of the liquid or sink marks due to drying, and transfer. This causes image disturbance in the image obtained.

  Furthermore, since the slippery coating layer exists on the surface of the intermediate transfer member in the form of a solidified film that has been once melted and cooled and solidified, adhesion is superior to releasability during transfer, and on the contrary, the transfer rate is increased. There is also a risk of lowering. This tendency is particularly strong when transfer is performed at high speed.

  The present invention has been made in view of such circumstances, and in the transfer recording method, image disturbance due to color material movement and expression of glossiness in a non-image portion on a recording medium are prevented, and high-speed transferability is achieved. An object of the present invention is to provide an image forming method and an image forming apparatus with improved image quality.

  In order to achieve the above object, an image forming method according to the present invention includes a step of forming a solid or semi-solid solution treatment agent layer comprising a treatment agent containing at least one kind of solid particles on an intermediate transfer member; In accordance with image data, a step of forming ink droplets on the surface of the processing agent layer formed on the intermediate transfer body and ejecting the ink, and the surface temperature of the intermediate transfer body is set to be lower than the melting point of the solid particles. Transferring the image from the intermediate transfer member to the recording medium in a state where the surface roughness (Ra) of the treatment agent layer formed on the intermediate transfer member is a color contained in the ink It is characterized by being larger than the particle diameter of the material.

  According to the present invention, since the color material is fixed to the concave portion formed on the surface of the processing agent layer on the intermediate transfer body, it is possible to prevent image disturbance due to color material movement. In addition, since the solid particles are transferred in a state where the particle shape is maintained without melting, transferability at high speed is improved, and glossiness can be prevented in a non-image portion on the recording medium. it can.

In the present specification, the “solid or semi-solid treatment agent (treatment agent layer)” refers to a treatment agent (treatment agent layer) having a moisture content in the range of 0 to 70%. The “moisture content” is the ratio of the weight X ₂ [g / m ² ] per unit area of water contained in the treatment agent to the weight X ₁ [g / m ² ] per unit area of the treatment agent (that is, , X ₂ / X ₁ ).

  In addition, the “treatment agent” is used in a broad concept including not only solid or semi-solid solution but also other liquid, and in particular, a treatment agent in a liquid state with a moisture content of 70%. Is referred to as “treatment liquid”.

  According to a second aspect of the present invention, there is provided the image forming method according to the first aspect, wherein the step of forming the solid or semi-solid treatment agent layer includes the treatment agent on the intermediate transfer member. And a step of drying the treatment agent applied on the intermediate transfer member to form a solid or semi-solid treatment agent layer comprising the treatment agent on the intermediate transfer member; It is characterized by including.

  As means for applying the treatment agent onto the intermediate transfer member, application means such as an application roller, an ink jet head, or the like can be applied. When using a coating means, a thin layer (treatment agent layer) having a uniform thickness can be formed. Further, when an ink jet head is used, it is possible to selectively apply a processing agent according to a recorded image (image data), and it is possible to reduce the processing agent and drying energy.

  A third aspect of the present invention relates to an aspect of the image forming method according to the first or second aspect, wherein the processing agent includes a component that aggregates the color material of the ink.

  In the present invention, it is preferable to use a treatment agent containing a component that aggregates the color material of the ink (color material aggregation component). When ink droplets land on the surface of a solid or semi-solid treatment agent layer made of such a treatment agent, an agglomeration reaction starts instantly, preventing the color material particles from floating, and preventing the movement of the color material. is there. In addition, the cohesive force of the color material constituting the ink image can be improved, the offset (separation) at the time of transfer is prevented, and the transfer property is more effective.

  According to a fourth aspect of the present invention, there is provided an image forming method according to any one of the first to third aspects, wherein the ink includes polymer fine particles.

  In the present invention, it is preferable to use ink containing polymer fine particles. Image disturbance can be suppressed by improving the cohesive strength of the ink, and transferability can be improved.

  The invention according to claim 5 relates to an aspect of the image forming method according to claim 4, wherein the surface temperature of the intermediate transfer member is higher than the glass transition temperature of the polymer fine particles, and the solid particles It is characterized by being lower than the melting point.

  According to the aspect of claim 5, transferability can be improved by fusing polymer fine particles.

  A sixth aspect of the present invention relates to an aspect of the image forming method according to any one of the first to fifth aspects, wherein the processing agent includes first solid particles and the first solid particles. Second solid particles having a melting point lower than that of the solid particles, the surface temperature of the intermediate transfer member is lower than the melting point of the first solid particles, and is lower than the melting point of the second solid particles. It is characterized by being expensive.

  According to the aspect of claim 6, the fixability and strength of the solid or semi-solid treatment agent layer are improved by melting the second solid particles without melting the first solid particles. Therefore, it is possible to reliably prevent image disturbance due to color material movement. In addition, it is possible to prevent a decrease in transferability due to the separation of the treatment agent layer during transfer.

  The particle size of the second solid particles is preferably smaller than the particle size of the first solid particles, and small particles (second solid particles) around the large particles (first solid particles) due to an action such as capillary force during drying. Solid particles) can be easily concentrated, and the fixation and strength of the treatment agent layer can be increased by melting the second solid particles.

  In order to achieve the above object, an apparatus invention is provided. That is, the invention according to claim 7 is a processing agent layer forming means for forming a solid or semi-solid processing agent layer comprising a processing agent containing at least one kind of solid particles on the intermediate transfer member, and image data. In response, the ink droplet ejecting means for dropletizing ink onto the surface of the treatment agent layer formed on the intermediate transfer member, and the surface temperature of the intermediate transfer member to be less than the melting point of the solid particles And a transfer means for transferring an image from the intermediate transfer body to a recording medium in a state where the surface roughness (Ra) of the treatment agent layer formed on the intermediate transfer body is contained in the ink. It is characterized by being larger than the particle diameter of the coloring material.

  The invention according to an eighth aspect relates to an aspect of the image forming apparatus according to the seventh aspect, wherein the processing agent layer forming unit applies the processing agent onto the intermediate transfer member, and the intermediate transfer. It comprises a means for drying the treatment agent applied on the body to form a solid or semi-solid treatment agent layer comprising the treatment agent on the intermediate transfer member. .

  According to the present invention, since the color material is fixed to the concave portion formed on the surface of the processing agent layer on the intermediate transfer body, it is possible to prevent image disturbance due to color material movement. In addition, since the solid particles are transferred in a state where the particle shape is maintained without melting, transferability at high speed is improved, and glossiness can be prevented in a non-image portion on the recording medium. it can.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Inkjet recording device]
FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. The ink jet recording apparatus 10 shown in FIG. 1 has a processing agent applying unit 16 for applying a processing agent (processing liquid) on the intermediate transfer body 12 and a processing agent applied on the intermediate transfer body 12 to dry the intermediate transfer body 12. A drying unit 18 for forming a solid or semi-solid treatment agent layer on the body 12, and an inkjet head corresponding to each color ink of cyan (C), magenta (M), yellow (Y), and black (K) ( Hereinafter, it is simply referred to as “head”.) A printing unit (ink droplet ejection unit) 20 having 20C, 20M, 20Y, and 20K and an ink image (primary image) formed on the intermediate transfer body 12 are recorded on the recording medium 14. It is mainly comprised from the transfer part 22 to transfer.

  The ink and the treatment agent (treatment liquid) used in the present invention will be described in detail later. In the present invention, an aqueous pigment ink containing a pigment that is a colorant (colorant), polymer fine particles, or the like is used as a solvent-insoluble material. Preferably used.

  In the present invention, a treating agent containing at least one kind of solid particles (first solid particles) is used. As the solid particles, a crystalline polymer such as a wax material is desirable. For example, polyethylene wax, paraffin wax and the like are preferable. The solid particles contained in the treating agent preferably have a melting point in the range of 50 to 140 ° C.

  It is preferable to use a treatment agent containing not only the first solid particles but also the second solid particles having a lower melting point than the first solid particles. The particle size of the second solid particles is preferably smaller than the particle size of the first solid particles. Improves the fixability and strength of the solid or semi-solid treatment agent layer formed on the intermediate transfer body 12, reliably prevents image distortion, and prevents the transferability from being deteriorated due to the separation of the treatment agent layer during transfer. be able to.

  Further, it is preferable to use a treatment agent containing a component that aggregates the color material of the ink (color material aggregation component). When ink droplets land on the surface of a solid or semi-solid treatment agent layer made of such a treatment agent, an agglomeration reaction starts instantly, preventing the color material particles from floating, and preventing the movement of the color material. is there. In addition, the cohesive force of the color material constituting the ink image can be improved, the offset (separation) at the time of transfer is prevented, and the transfer property is more effective.

  An endless belt is applied to the intermediate transfer member 12 shown in FIG. 1, and the intermediate transfer member (endless belt) 12 is wound around a plurality of stretching rollers (seven stretching rollers 24A to 24G are shown in FIG. 1). The intermediate transfer body 12 has the structure that is applied, and the power of the motor (not shown in FIG. 1 and indicated by reference numeral 88 in FIG. 6) is transmitted to at least one of the stretching rollers 24A to 24G. 1, it is driven in the counterclockwise direction (the direction indicated by arrow A in FIG. 1; hereinafter referred to as “intermediate transfer member conveyance direction”).

  The intermediate transfer member (endless belt) 12 is formed of resin or metal in an image forming region (not shown) on which at least a primary image (ink image) is formed on a surface (image forming surface) 12A facing the printing unit 20. And non-penetrable so that ink droplets such as rubber cannot penetrate. Further, at least the image forming area of the intermediate transfer body 12 is configured to form a horizontal surface (flat surface) having a predetermined flatness.

  In FIG. 1, an endless belt is shown as one embodiment of the intermediate transfer body 12, but the intermediate transfer body applied to the present invention may be a drum shape or a flat plate shape.

  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. If 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 reduced), and transferability is deteriorated. 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 agent is more than the surface tension of the surface layer of the intermediate transfer body 12 in consideration of the wettability of the processing agent. Therefore, it is difficult to make the surface tension of the processing agent 10 mN / m or less, and the design freedom (selection range) of the intermediate transfer member 12 and the processing agent becomes narrow.

  A processing agent application unit 16 that applies a processing agent (processing liquid) to the intermediate transfer body 12 is disposed on the most upstream side in the intermediate transfer body conveyance direction (the direction indicated by arrow A in FIG. 1). The processing agent application unit 16 includes an application roller 16A and a container 16B that stores the processing agent. The application roller 16A is driven to rotate with respect to the intermediate transfer member 12, or independently, the application roller 16A can be driven to control rotation. Thus, the processing roller 16A rotates to apply the processing agent in the container 16B to the image forming surface 12A of the intermediate transfer body 12.

  The coating thickness of the treatment agent on the intermediate transfer body 12 is preferably set in the range of 0.5 to 20 μm. If the coating thickness is less than 0.5 μm, film non-uniformity is likely to occur due to liquid breakage, resulting in a quality problem. On the other hand, if the coating thickness is larger than 20 μm, the energy addition in the drying process increases, and the surface condition also deteriorates.

  In order to control the coating thickness of the treatment agent, a mode in which the contact time between the coating roller 16A and the intermediate transfer body 12 is controlled is preferable. When the contact time between the coating roller 16A and the intermediate transfer body 12 is relatively long, the coating thickness of the processing agent is relatively large, and when the contact time between the coating roller 16A and the intermediate transfer body 12 is relatively short, the processing agent. The coating thickness of becomes relatively small.

  The application roller 16A is preferably a porous material or a material having irregularities on the surface, and for example, a gravure roll can be used.

  In FIG. 1, an embodiment using the application roller 16 </ b> A is illustrated as one embodiment of the treatment agent application form, but the treatment agent application form is not limited to this example, and various applications such as application by a blade, droplet ejection by an inkjet head, and the like. It is possible to apply various methods. In particular, in the case of the inkjet method, the processing agent can be accurately patterned and applied according to the recorded image (image data), and the heating time of the drying unit 18 disposed in the subsequent stage can be shortened and the heating energy can be reduced. It becomes possible.

  A drying unit 18 for drying the processing agent (processing liquid) applied on the intermediate transfer body 12 is disposed downstream of the processing agent applying unit 16 in the conveyance direction of the intermediate transfer body. The drying unit 18 includes a heater (not shown in FIG. 1, indicated by reference numeral 89 in FIG. 6), and dries the processing agent applied on the intermediate transfer body 12 by heating with the heater to perform intermediate transfer. A solid or semi-solid treatment agent layer (hereinafter simply referred to as “treatment agent layer”) is formed on the body 12.

  The heating temperature of the heater disposed in the drying unit 18 is set according to various conditions such as the type of the processing agent, the applied amount (thickness) of the processing agent, and the environmental temperature. In particular, in the present embodiment, the heating temperature of the heater is set so that the surface temperature of the intermediate transfer body 12 is lower than the melting point of the solid particles contained in the processing agent. Thereby, the solid particles contained in the treatment agent applied on the intermediate transfer body 12 are present in the treatment agent layer in a state in which the particle shape is maintained without melting, so that the surface of the treatment agent layer becomes uneven. . If heating is performed so that the surface temperature of the intermediate transfer member 12 is equal to or higher than the melting point of the solid particles, the particle shape of the solid particles collapses, and the surface of the treatment agent layer becomes flat, and the color Image disturbance due to material movement cannot be prevented, and transferability is also deteriorated. Accordingly, the heater disposed in the drying unit 18 is set to a heating temperature at which the surface temperature of the intermediate transfer body 12 is less than the melting point of the solid particles so that the solid particles contained in the processing agent are not melted. It is preferable.

  In this embodiment, the surface roughness (Ra) of the treatment agent layer formed on the intermediate transfer body 12 is configured to be larger than the colorant particle diameter (pigment particle diameter) of the ink. Specifically, the type of the processing agent (solid particles), the application amount (thickness) of the processing agent, the drying conditions (heating conditions), and the like are determined so as to satisfy the above-described relationship. When ink droplets are ejected onto the surface of the treatment agent layer in the printing unit 20 at the subsequent stage, the colorant particles (pigment particles) are trapped in the recesses formed on the surface of the treatment agent layer and cannot move. Therefore, image disturbance due to color material movement can be effectively prevented.

  The addition amount of the solid particles contained in the processing agent (that is, the coverage of the solid particles with respect to the surface area of the intermediate transfer member 12) is set to an appropriate amount according to the releasability of the surface material of the intermediate transfer member 12. Is desirable. Specifically, when the surface material of the intermediate transfer body 12 has a high releasability, the amount of solid particles added is reduced, whereas when the releasability is low, the amount of solid particles added is increased. . As will be described later, since transfer is performed in the transfer unit 22 so that the particle shape of the solid particles is maintained, the releasability of the treatment agent layer with respect to the intermediate transfer body 12 is increased by the solid particles, and high-speed transferability is achieved. Can be improved.

  In the present embodiment, it is preferable to use a treatment agent that includes the first solid particles and includes the second solid particles having a melting point lower than that of the first solid particles. In the drying unit 18, by drying the treatment agent at a heating temperature lower than the melting point of the first solid particles and higher than the melting point of the second solid particles, only the second solid particles are melted and the first solid particles are melted. Solid particles can be fixed. As a result, the fixing property and strength of the treatment agent layer itself are improved, image disturbance can be reliably prevented, and transferability can be prevented from being deteriorated due to the separation of the treatment agent layer during transfer.

  The addition amount of the second solid particles is desirably 10% or more and less than 100% with respect to the first solid particle amount. If it is less than 10%, the effect is insufficient, and if it is 100% or more (equal amount or more), the transferability is counterproductive.

  The particle diameter of the second solid particles is preferably smaller than the particle diameter of the first solid particles, and small particles (first solid particles) around the large particles (first solid particles) due to an action such as capillary force during drying. The second solid particles) are easily concentrated, and the fixation and strength can be improved by melting the second solid particles.

  In this embodiment, after applying a treatment agent (treatment liquid) containing solid particles on the intermediate transfer body 12, the treatment agent on the intermediate transfer body 12 is dried by heating to form a solid or semi-solid treatment agent layer. However, there is also an embodiment in which a solid or semi-solid treatment agent layer is directly formed on the intermediate transfer member 12. For example, a solid or semi-solid treatment agent layer is formed on the intermediate transfer body 12 by using a known powder spraying method such as a fluid dipping method, electrostatic fogging method, thermal spraying method, electrostatic dry spraying method, or spraying method. Can be formed directly. It is also possible to spray powder using a container having an opening provided with an openable / closable lid and capable of storing powder (treatment agent) inside. At this time, the lid is opened only when the intermediate transfer body 12 passes, and the powder is sprayed on the intermediate transfer body 12, the lid is closed when not in use, and a control means for adjusting the powder so as not to be sprayed is provided. It is also possible to precisely control the dispersal of the body.

  The printing unit 20 is disposed on the downstream side of the drying unit 18 in the intermediate transfer body conveyance direction, and sequentially from the upstream side along the intermediate transfer body conveyance direction, cyan (C), magenta (M), yellow (Y), black ( Heads 20C, 20M, 20Y and 20K corresponding to the respective color inks K) are provided. In the printing unit 20, ink droplets of corresponding colors are ejected from the heads 20 </ b> C, 20 </ b> M, 20 </ b> Y, and 20 </ b> K onto the intermediate transfer body 12 according to the image data. Ink droplets ejected from the heads 20C, 20M, 20Y, and 20K are solid or semi-solid treatment agent layers formed on the intermediate transfer body 12 upstream of the printing unit 20 in the intermediate transfer body conveyance direction. Land on the top.

  As shown in FIG. 2, each of the heads 20C, 20M, 20Y, and 20K 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 ejection surface thereof. A full-line head in which a plurality of nozzles for ink ejection (not shown in FIG. 2, not shown in FIG. 3) is arranged. The heads 20C, 20M, 20Y, and 20K are fixedly installed so as to extend in a direction orthogonal to the intermediate transfer member conveyance direction.

  According to the configuration in which a full line head having a nozzle row covering the entire width of the image forming area of the intermediate transfer body 12 is provided for each ink color, the intermediate transfer body 12 in the transport direction (sub-scanning direction) of the intermediate transfer body 12. The primary image can be recorded in the image forming area of the intermediate transfer member 12 only by performing the operation of relatively moving the printing unit 20 once (that is, by one sub-scan). As a result, high-speed printing is possible as compared with the case where a serial (shuttle) type head that reciprocates in the direction orthogonal to the intermediate transfer member conveyance direction (main scanning direction; see FIG. 3) is applied, and print productivity is improved. Can be improved.

  In this example, the minimum droplet ejection amount (ejection volume) of the ink droplets ejected from the nozzles of the heads 20C, 20M, 20Y, and 20K is 2 pl, and the maximum recording density (maximum dot density) is the main scanning direction ( Both in the direction orthogonal to the intermediate transfer member conveyance direction) and the sub-scanning direction (intermediate transfer member conveyance direction) are 1200 dpi.

  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 colors are used as necessary. Ink 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.

  The ink storage / loading unit 26 includes an ink tank (not shown in FIG. 1 and indicated by reference numeral 60 in FIG. 5) that stores color inks corresponding to the heads 20C, 20M, 20Y, and 20K. Each tank communicates with a corresponding head through a required flow path. Further, the ink storage / loading unit 26 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  A solvent removal unit 28 is disposed downstream of the printing unit 20 in the conveyance direction of the intermediate transfer member. The solvent removal unit 28 includes a solvent absorption roller 28A made of a roller-like porous body (absorber), and the solvent absorption roller 28A is used as a liquid solvent (a solvent component such as ink) on the intermediate transfer body 12. The liquid solvent is removed from the intermediate transfer body 12 by bringing the liquid solvent into contact with the porous body by the capillary force of the porous body.

  The solvent absorbing roller 28A may be driven to rotate according to the movement (conveyance) of the intermediate transfer body 12, or may be rotated independently. Further, it is preferable that the intermediate transfer body 12 is configured to be separated from the image forming surface 12A.

  The surface energy of the surface of the solvent absorbing roller 28A (the surface in contact with the image forming surface 12A of the intermediate transfer body 12) is preferably smaller than the surface energy of the image forming surface 12A of the intermediate transfer body 12, and in this example, the solvent absorption A member having a surface energy of 30 mN / m or less is applied to the roller 28A.

  By removing the solvent using the solvent absorbing roller 28A that satisfies the above-described surface energy conditions, the liquid solvent on the intermediate transfer body 12 can be absorbed and removed while preventing the coloring material from adhering to the solvent absorbing roller 28A. It becomes possible.

  Instead of the solvent absorbing roller 28A, a method of removing excess solvent from the intermediate transfer body 12 with an air knife, heating the intermediate transfer body 12 (for example, heating with a flat plate heater), or blowing dry air. A method of evaporating and removing the solvent may be applied. The solvent removal method may be any of the methods exemplified above, but it is more preferable to use a method that does not rely on heating.

  In the method of heating the surface of the intermediate transfer member 12 or the method of applying heat to the ink image on the intermediate transfer member 12 to evaporate the solvent, the solvent is excessively removed by overheating of the ink image, and at the time of transfer. The preferable viscoelasticity of the ink image cannot be maintained, and the transfer property to the recording medium 14 may be deteriorated. Furthermore, there is a concern that the heat generated by overheating affects the ejection performance of each head 20C, 20M, 20Y, 20K.

  On the other hand, in the embodiment in which the solvent on the image forming surface 12A of the intermediate transfer body 12 is absorbed and removed by the solvent absorbing roller 28A, even when a large amount of solvent remains on the intermediate transfer body 12, it takes less time than other methods. Since a large amount of solvent can be removed, a large amount of solvent (dispersion medium) is not transferred to the recording medium 14 by the transfer unit 22 at the subsequent stage. Therefore, even when paper is used as the recording medium 14, problems characteristic to aqueous solvents such as curls and cockles do not occur.

  Further, by removing the excess solvent from the ink image using the solvent removal unit 28, the ink image can be concentrated and the internal cohesive force can be further increased. Thereby, a stronger internal cohesive force can be imparted to the ink image up to the transfer step by the transfer unit 22. Further, effective concentration of the ink image by removing the solvent can impart good fixability and gloss to the image even after the image is transferred to the recording medium 14.

  Note that it is not always necessary to remove all the solvent on the intermediate transfer body 12 by the solvent removing unit 28. If the ink image is excessively removed by excessively removing it, the adhesion of the ink image to the intermediate transfer body 12 becomes too strong, and an excessive pressure is required for transfer, which is not preferable. 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 the ink image is hydrophobic and the solvent component that hardly volatilizes (mainly an organic solvent such as glycerin) is hydrophilic, the ink image and the residual solvent component are separated after the solvent is removed, and consist of the residual solvent component. A thin liquid layer is formed between the ink image and the intermediate transfer member. Accordingly, the adhesive force of the ink image to the intermediate transfer body 12 is weakened, which is advantageous for improving transferability.

  The solvent removal control described above can be performed by changing the pressure applied to the intermediate transfer body 12 by the solvent absorbing roller 28A. When the solvent removal amount is relatively increased, the pressure on the intermediate transfer body 12 of the solvent absorption roller 28A is increased, and when the solvent removal amount is relatively reduced, the intermediate transfer body of the solvent absorption roller 28A. What is necessary is just to make the press to 12 small.

  In addition, a mode in which a plurality of solvent absorption rollers having different absorption characteristics are provided and the solvent absorption roller to be used is selectively switched according to the amount of solvent removal is also possible.

  A preheating unit 30 is disposed between the solvent removal unit 28 and the transfer unit 22. The preheating unit 30 includes a heater (not shown in FIG. 1 and indicated by reference numeral 89 in FIG. 6) provided on the back surface 12B side of the image forming surface 12A of the intermediate transfer body 12. Before the ink image (primary image) formed on the intermediate transfer body 12 is transferred to the recording medium 14, preheating is performed from the back surface 12B side of the intermediate transfer body 12 by a heater. In this example, a flat plate heater is preferably used. In this example, the configuration in which the heater is disposed outside the intermediate transfer member 12 is illustrated, but the intermediate transfer member 12 may include a heater.

  The heating temperature range of the heater disposed in the preheating unit 30 is 40 to 80 ° C., and is set lower than the heating temperature at the time of transfer. By preheating the image forming area of the intermediate transfer body 12, the heating temperature of the transfer unit 22 can be set lower than when no preheating is performed, and the transfer time of the transfer unit 22 is further reduced. be able to.

  The transfer unit 22 disposed downstream of the preheating unit 30 in the conveyance direction of the intermediate transfer member has a transfer heating roller having heaters (not shown in FIG. 1 and representative of a plurality of heaters shown in FIG. 6 by reference numeral 89). 22A and a heating counter roller 22B for a heating and pressurizing nip disposed opposite thereto, the intermediate transfer body 12 and the recording medium 14 are sandwiched between these rollers 22A and 22B, and a predetermined temperature is set. The ink image (primary image) formed on the intermediate transfer body 12 is transferred to the recording medium 14 by pressurizing at a predetermined pressure (nip pressure) while heating at.

  The heating temperature (transfer temperature) by the transfer part 22 is preferably 80 ° C. to 170 ° C., and more preferably 100 ° C. to 150 ° C. from the viewpoint of transferability. When the heating temperature by the transfer unit 22 exceeds 170 ° C., there is a problem such as deformation of the intermediate transfer body 12, and when it is less than 80 ° C., there is a problem that transferability deteriorates.

  The nip pressure by the transfer unit 22 is preferably 1.5 to 2.0 MPa. In this example, it is set to 2.0 MPa. As a means for adjusting the nip pressure at the time of transfer in the transfer unit 22, for example, a mechanism (drive means) for moving the transfer heating roller 22A in the vertical direction (shown by C) in FIG. That is, when the transfer heating roller 22A is moved away from the heating counter roller 22B, the nip pressure decreases, and when it is moved closer to the heating counter roller 22B, the nip pressure increases.

  In the present embodiment, the heating temperature of the preheating unit 30 and the transfer unit 22 is set so that the temperature of the image forming surface 12A of the intermediate transfer body 12 (the temperature of the region where the image is formed) is lower than the melting point of the solid particles. Preferably it is set. When heated above the melting point of the solid particles, the adhesiveness of the treatment agent layer to the intermediate transfer body 12 increases due to melting of the solid particles, and the transferability to the recording medium 14 decreases. In addition, since the solid particles are melted and transferred in a smooth state to the non-image portion of the recording medium 14, unnatural glare, shine, etc. occur, and the texture is impaired.

  Further, when ink containing polymer fine particles is used, the temperature of the image forming surface 12A of the intermediate transfer body 12 (the temperature of the region where the image is formed) exceeds the glass transition temperature Tg of the polymer fine particles. Further, it is preferable that the heating temperature of the preheating unit 30 and the transfer unit 20 is set. That is, the order of temperature is, from the highest, the melting point of the solid particles, the surface temperature of the intermediate transfer body 12 (the temperature of the image forming surface 12A), and the glass transition temperature Tg of the polymer fine particles.

  The configuration of the paper supply unit 32 that supplies the recording medium 14 to the transfer unit 22 is an aspect in which a magazine for rolled paper (continuous paper) is provided, or a cut paper instead of or in combination with a magazine for rolled paper. There is a mode in which paper is supplied by a cassette loaded with stacks. 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 and inkjet exclusive paper, non-permeable or low permeable media such as coated paper, and adhesive and release labels on the back surface. There are various media such as sticker paper, resin films such as OHP sheets, metal sheets, cloth, and wood.

  A mode in which the cooling unit 34 is disposed downstream of the transfer unit 22 in the conveyance direction of the intermediate transfer member is preferable. The cooling unit 34 cools the intermediate transfer member 12 and the recording medium 14 that are past each other through the transfer unit 22. The cooling unit 34 is preferably applied with a mode in which cool air is blown by a cooling fan or the like, and the cooling temperature or the like can be adjusted. The cooling unit 34 shown in this example has a configuration in which a moving time (cooling time) of the intermediate transfer body 12 for cooling to a desired temperature is secured. By peeling the intermediate transfer body 12 and the recording medium 14 after cooling, transfer failure due to temperature unevenness or the like can be prevented, and stable image transfer (peeling) becomes possible.

  A peeling unit 36 is disposed on the downstream side of the cooling unit 34 in the conveyance direction of the intermediate transfer member. The peeling unit 36 is configured to peel the recording medium 14 from the intermediate transfer body 12 with the rigidity (waist strength) of the recording medium 14 itself by the winding curvature of the peeling roller 24E of the intermediate transfer body 12. The peeling part 36 may be used in combination with a means for promoting peeling such as a peeling nail.

  A fixing unit 38 is disposed downstream of the peeling unit 36 in the recording medium conveyance direction (the direction indicated by arrow B in FIG. 1). The fixing unit 38 includes a heating roller pair 38A whose temperature can be adjusted in a range of 100 ° C. to 180 ° C., and heats and presses the recording medium 14 sandwiched between the heating roller pair 38A. The image transferred to the image is fixed.

  In the present embodiment, the heating temperature of the fixing unit 38 is preferably set so that the surface temperature of the recording medium 14 is equal to or higher than the melting point of the solid particles. In addition, when ink containing polymer fine particles is used, it is preferable that the heating temperature of the fixing unit 38 is set so that the temperature exceeds the glass transition temperature Tg of the polymer fine particles. That is, the order of temperature is, in order from the highest, the melting point of the solid particles, the surface temperature of the recording medium 14, and the glass transition temperature Tg of the polymer fine particles. In this example, the heating temperature of the fixing unit 38 is set to 150 ° C.

  The nip pressure of the fixing unit 38 is preferably 0.1 to 1.0 MPa, and is set to 0.8 MPa in this example. Note that if the transfer unit 22 can achieve both image transfer and fixing, the fixing unit 38 may be omitted.

  Since solid particles such as polyethylene wax and paraffin wax are present in the outermost layer of the image after transfer and fixing, they function as a protective layer and have an effect of improving the durability of the image such as abrasion resistance.

  A cleaning unit 40 is disposed downstream of the peeling unit 36 in the conveyance direction of the intermediate transfer member. The cleaning unit 40 is a means for cleaning the intermediate transfer body 12 after the image transfer to the recording medium 14 is performed, and a post-transfer residue (coloring material or the like) while contacting the image forming surface 12A of the intermediate transfer body 12. And a recovery unit (not shown) for recovering the removed post-transfer residue.

  The configuration of the cleaning means for removing the post-transfer residue from the intermediate transfer body 12 is not limited to the above example, but a method of niping a brush roll, a water absorption roll, etc., an air blow method of blowing clean air, an adhesive roll There are methods or combinations thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Next, the structure of the heads 20C, 20M, 20Y, and 20K arranged in the printing unit 20 will be described in detail. Since the structures of the heads 20C, 20M, 20Y, and 20K are common, the head is represented by the reference numeral 50 in the following.

  3A is a plan perspective view showing a structural example of the head 50, FIG. 3B is an enlarged view of a part thereof, and FIG. 3C is a plan view showing another structural example of the head 50. FIG. FIG. 4 is a cross-sectional view (a cross-sectional view taken along line 4-4 in FIGS. 3A and 3B) showing a three-dimensional configuration of the ink chamber unit.

  In order to increase the dot pitch formed on the intermediate transfer body 12, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 3A and 3B, the head 50 of this example includes a plurality of ink chamber units 53 including nozzles 51 that are ink droplet ejection holes and pressure chambers 52 corresponding to the nozzles 51. Are arranged in a staggered matrix (two-dimensionally), so that the projections are substantially arranged so as to be aligned along the longitudinal direction of the head (main scanning direction perpendicular to the conveyance direction of the intermediate transfer member). High nozzle density (projection nozzle pitch) is achieved.

  The form in which one or more nozzle rows are formed over a length corresponding to the entire width of the intermediate transfer body 12 in a direction substantially orthogonal to the conveyance direction of the intermediate transfer body 12 is not limited to this example. For example, instead of the configuration of FIG. 3A, as shown in FIG. 3C, short head blocks 50 ′ in which a plurality of nozzles 51 are two-dimensionally arranged are arranged in a staggered manner and joined together. A line head having a nozzle row having a length corresponding to the entire width of the intermediate transfer body 12 may be configured. Although not shown, a line head may be configured by arranging short heads in a line.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and the nozzle 51 and the supply port 54 are provided at both corners on the diagonal line. Each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common flow channel 55 communicates with an ink supply tank (not shown in FIG. 4; indicated by reference numeral 60 in FIG. 5) as an ink supply source, and the ink supplied from the ink supply tank passes through the common flow channel 55. Distribution is supplied to each pressure chamber 52.

  A piezoelectric element 58 having an individual electrode 57 is joined to a diaphragm 56 that constitutes the top surface of the pressure chamber 52 and also serves as a common electrode. By applying a driving voltage to the individual electrode 57, the piezoelectric element 58 is Deformation causes ink to be ejected from the nozzle 51. When ink is ejected, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

  In this example, the piezoelectric element 58 is applied as a means for generating ink ejection force ejected from the nozzles 51 provided in the head 50. However, a heater is provided in the pressure chamber 52, and the pressure of film boiling caused by heating of the heater is used. It is also possible to apply a thermal method that ejects ink.

  As shown in FIG. 3B, the ink chamber units 53 having such a structure are arranged in a fixed manner along a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. By arranging a large number of patterns in a lattice pattern, the high-density nozzle head of this example is realized.

  That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the sub-scanning direction can be applied.

  The scope of application of the present invention is not limited to the printing method using a line-type head, and a short head that does not reach the length in the width direction (main scanning direction) of the intermediate transfer body 12 is scanned in the width direction of the intermediate transfer body 12. Then, the printing in the width direction is performed, and when the printing in the width direction is completed once, the intermediate transfer body 12 is moved by a predetermined amount in the direction (sub-scanning direction) orthogonal to the width direction, and the middle of the next printing area A serial method in which printing in the width direction of the transfer body 12 is performed and printing is performed over the entire printing area of the intermediate transfer body 12 by repeating this operation may be applied.

  FIG. 5 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. As shown in FIG. 5, the ink supply tank 60 is a base tank that supplies ink to the head 50, and is included in the ink storage / loading unit 26 described with reference to FIG. The ink supply tank 60 includes a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

  As shown in FIG. 5, a filter 62 is provided between the ink supply tank 60 and the head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm).

  Although not shown in FIG. 5, a configuration in which a sub tank is provided in the vicinity of the head 50 or integrally with the head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the ink discharge surface of the head 50. Yes.

  The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the head 50 as necessary.

  The cap 64 is displaced up and down relatively with respect to the head 50 by an elevator mechanism (not shown). The cap 64 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the head 50, thereby covering the nozzle surface with the cap 64.

  During printing or standby, if the frequency of use of a specific nozzle 51 is reduced and ink is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the ink viscosity increases. In such a state, ink cannot be ejected from the nozzle 51 even if the piezoelectric element 58 operates.

  Before such a state is reached (within the range of viscosity that can be discharged by the operation of the piezoelectric element 58), the piezoelectric element 58 is operated, and a cap is formed to discharge the deteriorated ink (ink in the vicinity of the nozzle whose viscosity has increased). Preliminary ejection (purge, idle ejection, collar ejection, dummy ejection) is performed toward 64 (ink receiver).

  A mode in which preliminary ejection is performed by ejecting ink toward the intermediate transfer member 12 is also possible. For example, when a plurality of images are continuously formed, preliminary ejection can be performed between images. In particular, when a plurality of the same images are formed, the frequency of ink ejection at a specific nozzle is reduced, and the possibility of occurrence of ejection abnormality is increased, so that preliminary ejection can be performed between images for the specific nozzle. preferable.

  When preliminary discharge is performed on the intermediate transfer body 12, the solvent absorption roller 28A and the transfer heating roller 22A are moved so that the ink by the preliminary discharge does not adhere to the solvent absorption roller 28A and the transfer heating roller 22A. A predetermined clearance (for example, about 10 mm) may be provided between 28A and the transfer heating roller 22A and the intermediate transfer body 12.

  Further, when air bubbles are mixed in the ink in the head 50 (in the pressure chamber 52), the ink cannot be ejected from the nozzle even if the piezoelectric element 58 is operated. In such a case, the cap 64 is applied to the head 50, the ink in the pressure chamber 52 (ink mixed with bubbles) is removed by suction with the suction pump 67, and the suctioned and removed ink is sent to the recovery tank 68.

  In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time. Since the suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption increases. Therefore, it is preferable to perform preliminary ejection when the increase in ink viscosity is small.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink ejection surface of the head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matter adhere to the ink ejection surface, the ink ejection surface is wiped by sliding the cleaning blade 66 on the ink ejection surface, and the ink ejection surface is cleaned.

  FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, a memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, 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 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the memory 74.

  The memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The memory 74 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 72 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 72 controls each part such as the communication interface 70, the memory 74, the motor driver 76, the heater driver 78, etc., performs communication control with the host computer 86, read / write control of the memory 74, etc. A control signal for controlling the motor 88 and the heater 89 is generated.

  The memory 74 stores programs executed by the CPU of the system controller 72 and various data necessary for control. Note that the memory 74 may be a non-rewritable storage means or a rewritable storage means such as an EEPROM. The memory 74 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 76 is a driver that drives the motor 88 in accordance with instructions from the system controller 72. In FIG. 6, the motor (actuator) disposed in each part in the apparatus is represented by reference numeral 88. For example, the motor 88 shown in FIG. 6 includes a motor for driving the driving roller among the rollers 24A to 24G in FIG. 1, a motor for the moving mechanism of the solvent absorbing roller 28A, a motor for the moving mechanism of the transfer heating roller 22A, and the like. include.

  The heater driver 78 is a driver that drives the heater 89 in accordance with an instruction from the system controller 72. In FIG. 6, a plurality of heaters provided in the ink jet recording apparatus 10 are represented by reference numeral 89. For example, the heater 89 shown in FIG. 6 includes the heater of the drying unit 18 shown in FIG. 1, the heater of the preheating unit 30, the heater included in the heating roller pair 38A of the fixing unit 38, and the like.

  The transfer control unit 79 performs pressure control and temperature control of the transfer heating roller 22 </ b> A of the transfer unit 22. For each type of recording medium 14 and each type of ink, the optimum pressing value and the optimum temperature value of the transfer heating roller 22A are obtained in advance, stored in a predetermined memory (for example, the memory 74) and stored in a predetermined memory (for example, the memory 74). And the information on the ink used are acquired, the pressure and temperature of the transfer heating roller 22A are controlled with reference to the memory.

  The print control unit 80 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the memory 74 in accordance with the control of the system controller 72. The generated print data This is a control unit that supplies (dot data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the head 50 are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  The treatment agent application control unit 81 controls the amount of treatment agent (treatment liquid) applied by the application roller 16A shown in FIG. In this example, the intermediate transfer body 12 and the application roller 16A can be contacted and separated, and the application time of the processing agent is controlled by varying the time during which the application roller 16A is in contact with the intermediate transfer body 12.

  Further, a sensor for detecting the remaining amount of the processing agent in the container 16B is provided, and the processing agent application control unit 81 determines the remaining amount of the processing agent in the container 16B based on information obtained from the sensor, and the remaining amount is determined. When the amount falls below a predetermined amount, this is notified.

  The head driver 84 generates a drive signal to be applied to the piezoelectric element 58 of the head 50 based on the image data given from the print control unit 80, and drives the piezoelectric element 58 by applying the drive signal to the piezoelectric element 58. Including a driving circuit. The head driver 84 shown in FIG. 6 may include a feedback control system for keeping the driving condition of the head 50 constant.

  Data of an image to be printed is input from the outside via the communication interface 70 and stored in the memory 74. At this stage, RGB image data is stored in the memory 74.

  The image data stored in the memory 74 is sent to the print controller 80 via the system controller 72, and is converted into dot data for each ink color by the print controller 80. That is, the print control unit 80 performs processing for converting the input RGB image data into dot data of four colors of CMYK. The dot data generated by the print controller 80 is stored in the image buffer memory 82.

  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 during transfer. That is, the drive signal supplied to the head 50 is a drive signal corresponding to the mirror image, and the print control unit 80 needs to invert the input image.

  Various control programs are stored in the program storage unit 90, and the control programs are read and executed in accordance with instructions from the system controller 72. The program storage unit 90 may use a semiconductor memory such as a ROM or an EEPROM, or may use a magnetic disk or the like. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media. The program storage unit 90 may also be used as a recording means (not shown) for operating parameters.

  Next, the operation of the inkjet recording apparatus 10 described above will be described.

  In FIG. 1, the intermediate transfer member 12 is conveyed in the intermediate transfer member conveyance direction (the direction indicated by arrow A in FIG. 1), and first, the treatment agent (treatment liquid) is intermediated by the application roller 16A of the treatment agent application unit 16. It is applied onto the transfer body 12 (processing agent application step). Subsequently, the treatment agent on the intermediate transfer body 12 is dried by heating by the heater of the drying unit 18, and a solid or semi-solid treatment agent layer is formed on the intermediate transfer body 12 (treatment agent drying step). ).

  In the present embodiment, the heating temperature of the drying unit 18 is set so that the surface temperature of the intermediate transfer body 12 is lower than the melting point of the solid particles. Further, the processing agent (so that the surface roughness (Ra) of the solid or semi-solid processing agent layer formed on the intermediate transfer body 12 is larger than the colorant particle size (pigment particle size) of the ink. The type of solid particles), the amount of treatment agent applied (thickness), and the drying conditions (heating conditions) are determined.

  Next, ink droplets of each color are ejected by the heads 20C, 20M, 20Y, and 20K of the printing unit 20 onto the intermediate transfer body 12 on which the solid or semi-solid treatment agent layer is formed ( Ink droplet ejection process). When the ink droplets land on the surface of the treatment agent layer, the ink colorant particles (pigment particles) are fixed to the recesses formed on the surface of the treatment agent layer, so that image disturbance due to colorant movement is prevented.

  Next, the liquid solvent (such as the solvent component of the ink) on the intermediate transfer body 12 is absorbed and removed by the solvent absorbing roller 28A of the solvent removing unit 28 (solvent removing step).

  Next, the ink image on the intermediate transfer body 12 is preheated by the preheating unit 30 (preheating process), and the ink image formed on the intermediate transfer body 12 by the transfer unit 22 is transferred to the recording medium 14 ( Transfer process).

  In the present embodiment, it is preferable that the heating temperature of the preliminary heating unit 30 and the transfer unit 22 is set so that the surface temperature of the intermediate transfer body 12 is lower than the melting point of the solid particles. When ink containing polymer fine particles is used, the heating temperature of the preliminary heating unit 30 and the transfer unit 22 is set so that the surface temperature of the intermediate transfer body 12 is higher than the glass transition temperature Tg of the polymer resin. It is preferable.

  Next, the intermediate transfer body 12 and the recording medium 14 are cooled in the cooling section 34 (cooling process), and the recording medium 14 is peeled from the intermediate transfer body 12 by the peeling section 36 (peeling process). Thus, it is preferable that a cooling process is performed between a transfer process and a peeling process, and the peelability of the recording medium 14 can be improved.

  The recording medium 14 peeled off from the intermediate transfer body 12 is heated and pressurized by the heating roller pair 38A of the fixing unit 38, and the ink image transferred to the recording medium 14 is fixed (fixing step).

  In the present embodiment, the heating temperature of the fixing unit 38 is preferably set so that the surface temperature of the recording medium 14 is equal to or higher than the melting point of the solid particles. When ink containing polymer fine particles is used, it is preferable that the heating temperature of the fixing unit 38 is set so that the surface temperature of the recording medium 14 is higher than the glass transition temperature Tg of the polymer resin.

  On the other hand, the post-transfer residue on the intermediate transfer body 12 from which the recording medium 14 has been peeled is removed by the cleaning unit 40 (cleaning step). Thereafter, the above-described steps are sequentially repeated.

  According to this embodiment, since the color material is fixed to the concave portion formed on the surface of the processing agent layer on the intermediate transfer body 12, it is possible to prevent image disturbance due to color material movement. Further, since the solid particles are transferred in a state where the particle shape is maintained without being melted, the transfer property at high speed is improved and the glossiness in the non-image portion on the recording medium 14 is prevented. Can do.

  In the present embodiment, it is preferable to use a treatment agent containing a component (color material aggregation component) that aggregates the color material (pigment) of the ink. When ink droplets land on the surface of a solid or semi-solid treatment agent layer made of such a treatment agent, an agglomeration reaction starts instantly, and the floating of the color material particles (pigment particles) can be prevented. More effective in preventing. In addition, the cohesive force of the color material constituting the ink image can be improved, the offset (separation) at the time of transfer is prevented, and the transfer property is more effective.

[Description of ink]
The ink used in the present invention is a water-based pigment ink containing a pigment that is a coloring material (coloring agent) or polymer fine particles as a solvent-insoluble material.

The concentration of the solvent-insoluble material is preferably 1% by mass or more and 20% by mass or less in consideration of the viscosity of 20 mPa · s or less suitable for ejection. More preferably, the pigment concentration is 4% by mass or more in order to obtain the optical density of the image.
The surface tension of the ink is preferably 20 mN / m or more and 40 mN / m in consideration of ejection stability.

  The color material used in the ink can be a pigment or a mixture of a dye and a pigment. From the viewpoint of aggregability at the time of contact with the treatment liquid, a pigment in a dispersed state in the ink is preferable because it aggregates more effectively. Among the pigments, a pigment dispersed by a dispersant, a self-dispersing pigment, a pigment whose surface is coated with a resin (microcapsule pigment), and a polymer graft pigment are particularly preferable. From the viewpoint of pigment aggregation, a form modified with a carboxyl group having a low dissociation degree is more preferable.

  The resin of the microcapsule pigment is not limited, but is preferably a high molecular compound having a self-dispersibility or solubility in water and an anionic group (acidic). This resin usually has a number average molecular weight of preferably about 1,000 to 100,000, and particularly preferably about 3,000 to 50,000. Further, it is preferable that this resin is dissolved in an organic solvent to form a solution. When the number average molecular weight of the resin is within this range, the function as a coating film in the pigment or as a coating film in the ink composition can be sufficiently exhibited.

  The resin may be self-dispersible or soluble, or may have a function added by some means. For example, it may be a resin in which an anionic group such as a carboxyl group, a sulfonic acid group, or a phosphonic acid group is introduced by neutralization with an organic amine or an alkali metal. Further, it may be a resin into which one or two or more anionic groups of the same type or different types are introduced. In the present invention, a resin in which a carboxyl group is introduced by neutralization with a base is preferably used.

  Although it does not specifically limit as a pigment used for this invention, As a specific example, as a pigment for orange or yellow, C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185. Examples of red or magenta pigments include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  In the colored ink liquid according to the present invention, it is preferable to add polymer fine particles not containing a colorant as a component that reacts with the treatment liquid. The polymer fine particles can enhance the thickening action and aggregation action of the ink by reaction with the treatment liquid, and can improve the image quality. In particular, a highly safe ink can be obtained by incorporating anionic polymer fine particles into the ink.

  By using polymer fine particles that react with the treatment liquid and cause thickening and aggregating action in the ink, the quality of the image can be improved. At the same time, depending on the type of polymer fine particles, the polymer fine particles form a film on the recording medium. It also has the effect of improving the scratch resistance and water resistance of the image.

  The dispersion method in the polymer ink is not limited to emulsion, and it may be dissolved or exist in a colloidal dispersion state.

  The polymer fine particles may be obtained by dispersing the polymer fine particles using an emulsifier, or may be dispersed without using an emulsifier. As the emulsifier, a low molecular weight surfactant is usually used, but a high molecular weight surfactant can also be used as an emulsifier. It is also preferable to use capsule type polymer fine particles (core / shell type polymer fine particles having different compositions at the center and outer edge of the particle) whose outer shell is made of acrylic acid, methacrylic acid or the like.

  As a dispersion method, polymer fine particles not using a low molecular weight surfactant are called soap-free latex, including polymer fine particles using a high molecular weight surfactant and polymer fine particles not using an emulsifier. For example, a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group described above (a polymer in which a solubilizing group is graft-bonded, a monomer having a solubilizing group, and an insoluble portion) Polymer fine particles using a block polymer obtained from a monomer as an emulsifier are also included.

  In the present invention, it is particularly preferable to use this soap-free latex. The soap-free latex, compared with polymer fine particles polymerized using a conventional emulsifier, inhibits the reaction aggregation and film formation of the polymer fine particles, or the free emulsifier. However, it moves to the surface after forming the polymer fine particles, and there is no concern that the adhesiveness between the aggregate in which the pigment and the polymer fine particles are mixed and the recording medium is lowered.

  Examples of the resin component added to the ink as polymer fine particles include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, styrene resins, and the like.

  From the viewpoint of imparting high-speed cohesiveness to the polymer fine particles, those having a carboxylic acid group having a low dissociation degree are more preferable. Since the carboxylic acid group is easily affected by pH change, the dispersion state is easily changed and the cohesiveness is high.

  The change of the dispersion state with respect to the pH change of the polymer fine particles can be adjusted by the content ratio of the constituent component in the polymer fine particles having a carboxylic acid group such as an acrylate ester, and the like depending on the anionic surfactant used as the dispersant. Can also be adjusted.

  The resin component of the polymer fine particles is preferably a polymer having both a hydrophilic portion and a hydrophobic portion. By having the hydrophobic portion, the hydrophobic portion is oriented inside the polymer fine particle, the hydrophilic portion is efficiently oriented outside, and the effect of increasing the dispersion state with respect to the pH change of the liquid is greater, and aggregation is caused. It is done more efficiently.

  Examples of commercially available polymer fine particles include Jonkrill 537, 7640 (styrene-acrylic resin emulsion, manufactured by Johnson Polymer Co., Ltd.), Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, Nippon Paint Co., Ltd.). Manufactured), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin) Emulsion, manufactured by Nippon Zeon Co., Ltd., Jurimer ET-410, FC-30 (acrylic resin emulsion, manufactured by Nippon Pure Chemicals Co., Ltd.), Aron HD-5, A-104 (acrylic resin emulsion, manufactured by Toagosei Co., Ltd.) ), Cybino Le SK-200 (acrylic resin emulsion, manufactured by Saiden Chemical Industry Co., Ltd.), Zaikthene L (acrylic resin emulsion, manufactured by Sumitomo Seika Chemicals Co., Ltd.) and the like, not limited to this.

  The mass ratio of the amount of polymer fine particles added to the pigment is preferably 2: 1 to 1:10, more preferably 1: 1 to 1: 3. If the mass ratio of the polymer fine particles added to the pigment is less than 2: 1, the cohesive strength of the aggregate due to resin fusion will not be improved effectively. Moreover, even if the addition amount is more than 1:10, the viscosity of the ink becomes too high, and the discharge properties and the like deteriorate.

  The molecular weight of the polymer fine particles added to the ink is preferably 5,000 or more in view of the adhesive force when fused. If it is less than 5,000, the effect of improving the internal cohesive force of the ink aggregate when aggregated, fixing the image on the recording medium, and the effect of improving the image quality are insufficient.

  The volume average particle diameter of the polymer fine particles is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 500 nm, still more preferably in the range of 20 to 200 nm, and particularly preferably in the range of 50 to 200 nm. If the thickness is 10 nm or less, the effect of improving the image quality and the improvement of transferability cannot be expected even if they are aggregated. When the thickness is 1 μm or more, there is a concern that the ejection properties of the ink from the head and the storage stability may deteriorate. Moreover, there is no restriction | limiting in particular regarding the volume average particle diameter distribution of a polymer particle, What has a wide volume average particle diameter distribution or a thing with a monodispersed volume average particle diameter distribution may be sufficient.

  Further, two or more kinds of polymer fine particles may be mixed and used in the ink.

  As the pH adjuster added to the ink of the present invention, an organic base or an inorganic alkali base can be used as a neutralizing agent. The pH adjusting agent is preferably added so that the inkjet ink has a pH of 6 to 10 for the purpose of improving the storage stability of the inkjet ink.

  The ink of the present invention preferably contains a water-soluble organic solvent for the purpose of preventing clogging of the nozzles of the inkjet head due to drying. Such water-soluble organic solvents include wetting agents and penetrants.

  Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents and the like, as in the case of the treatment liquid. Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin. Examples of polyhydric alcohol derivatives include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and diglycerin. Examples include ethylene oxide adducts. Examples of nitrogen-containing solvents include pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, and triethanolamine. Examples of alcohols include alcohols such as ethanol, isopropyl alcohol, butyl alcohol, and benzyl alcohol. Thiodiethanol, thiodiglycerol, sulfolane, dimethyl sulfoxide and the like. In addition, propylene carbonate, ethylene carbonate, or the like can be used.

  The ink of the present invention can 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 (Air Products & 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.

  Further, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used. In addition, fluorine (fluorinated alkyl) and silicone surfactants as described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are also used. Can do. These surface tension modifiers can also be used as antifoaming agents, and fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can also be used.

  The surface tension can be lowered to increase the wettability on the solid or semi-solid treatment agent layer, and the spreading rate can be increased.

  The surface tension of the ink of the present invention is preferably from 10 to 50 mN / m. When direct recording is performed, the penetrability to the permeable recording medium, and when recording is performed by the intermediate transfer method, the intermediate transfer member is used. From the viewpoint of achieving both the wettability above, the formation of fine droplets and the discharge properties, it is more preferably 15 to 45 mN / m.

  The viscosity of the ink of the present invention is preferably 1.0 to 20.0 cP.

  In addition, a pH buffer, an antioxidant, a fungicide, a viscosity modifier, a conductive agent, an ultraviolet absorber, and the like can be added as necessary.

[Description of treatment agent (treatment liquid)]
The treatment liquid according to the present invention is preferably a treatment liquid that aggregates pigments and polymer fine particles contained in the ink by changing the pH of the ink, thereby generating an aggregate.

  Treatment liquid components include 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 It is preferably selected from 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.

  A preferable example of the treatment liquid according to the present invention is a treatment liquid to which a polyvalent metal salt or polyallylamine is added. These compounds may be used alone or in combination of two or more.

  The treatment liquid according to the present invention 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. .

  In the treatment liquid according to the present invention, the amount of the component that aggregates the pigment of the ink and the polymer fine particles is preferably 0.01% by mass or more and 20% by mass or less with respect to the total weight of the liquid. When the amount is 0.01% by mass or less, when the treatment liquid and the ink are in contact with each other, the concentration diffusion does not proceed sufficiently and the aggregation action due to the pH change may not occur sufficiently. On the other hand, when the content is 20% by mass or more, the dischargeability from the ink jet head may deteriorate.

  The treatment liquid according to the present invention preferably contains water and other additive-soluble organic solvents for the purpose of preventing clogging of the nozzles of the inkjet head 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 mass or less based on the total weight of the treatment liquid. When the amount is more than 60% by mass or more, the viscosity of the treatment liquid increases, and the dischargeability from the inkjet head may deteriorate.

  The treatment 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 mass to 20% by mass. 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 point 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.

  The coagulability may be further enhanced by adding polymer fine particles having a polarity opposite to that of the ink to the treatment liquid and aggregating with the pigment and polymer fine particles in the ink.

  In addition, a curing agent corresponding to the polymer fine particle component contained in the ink is contained in the treatment liquid, and after the two liquids contact, the resin emulsion in the ink component aggregates and crosslinks or polymerizes to increase the cohesiveness. Also good.

  The treatment liquid according to the present invention can 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 (Air Products & 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.

  Further, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used. In addition, fluorine (fluorinated alkyl) and silicone surfactants as described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are also used. Can do. These surface tension modifiers can also be used as antifoaming agents, and fluorine-based, silicone-based compounds, chelating agents represented by EDTA, and the like can also be used.

  This is effective in reducing the surface tension and increasing the wettability on the intermediate transfer member. Further, even when ink is ejected in advance, the wettability on the ink is enhanced, and the cohesive action is effectively promoted by increasing the contact area of the two liquids.

  The surface tension of the treatment liquid according to the present invention is preferably 10 to 50 mN / m. When direct recording is performed, the penetrability into the permeable recording medium, or when recording is performed by an intermediate transfer method, From the viewpoint of achieving both wettability on the intermediate transfer member, fine droplet formation and ejection properties, it is more preferably 15 to 45 mN / m.

  The viscosity of the treatment liquid according to the present invention is preferably 1.0 to 20.0 cP.

  In addition, pH buffering agents, antioxidants, fungicides, viscosity modifiers, conductive agents, ultraviolet rays, absorbents, and the like can be added as necessary.

  Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

  Hereinafter, evaluation experiments conducted to confirm the effects of the present invention will be described.

(Composition of ink and treatment agent)
The composition of the ink and treatment agent used in this evaluation experiment is shown in FIGS. The fluorine-based surfactant shown in FIG. 9 is represented by the following chemical formula.

  Inks 1a to 1c shown in FIG. 7 are inks that do not contain polymer fine particles, and have the same composition except that the particle diameter (pigment particle diameter) of the coloring material (pigment) is different. Specifically, the pigment particle sizes of the inks 1a, 1b, and 1c are 100 nm, 62 nm, and 151 nm, respectively.

  On the other hand, the inks 2a to 2e shown in FIG. 8 are inks containing polymer fine particles and have the same composition except that the pigment particle diameter and the glass transition temperature Tg of the polymer fine particles are different. Specifically, the pigment particle diameters of the inks 2a, 2b, 2c, 2d, and 2e are 100 nm, 62 nm, 151 nm, 100 nm, and 100 nm, respectively. The glass transition temperatures Tg of the polymer fine particles of the inks 2a, 2b, 2c, 2d, and 2e are 46 ° C., 46 ° C., 46 ° C., 66 ° C., and 85 ° C., respectively.

  Moreover, among the processing agents 1-8 shown in FIG. 9, the processing agents 1-5, 7 are processing agents containing one type of solid particles. Specifically, the solid particles of treatment agent 1 have a melting point of 110 ° C. and a particle size of 0.65 μm, the solid particles of treatment agent 2 have a melting point of 132 ° C. and a particle size of 1 μm, and the solid particles of treatment agent 3 have a melting point of 132. The solid particles of the treatment agent 4 have a melting point of 66 ° C. and a particle size of 0.3 μm, and the solid particles of the treatment agent 5 have a melting point of 70 ° C. and a particle size of 1 μm. The solid particles of the treatment agent 7 have a melting point of 132 ° C. and a particle size of 3 μm.

  On the other hand, the processing agents 6 and 8 are processing agents containing two types of solid particles. Specifically, each of the treatment agents 6 and 8 includes first and second solid particles, the first solid particles have a melting point of 132 ° C. and a particle size of 3 μm, and the second solid particles have a melting point of 50 ° C. and a particle size. 0.02 μm.

  Moreover, the processing agents 6 and 8 are the processing agents containing the component (phosphoric acid) which aggregates ink among the processing agents 1-8.

  The particle diameter of the solid particles and the ink coloring material (pigment particles) contained in the treatment agent can be measured using Microtrac UPA (manufactured by Nikkiso Co., Ltd.). Further, the melting point of solid particles, the softening point of polymer fine particles (glass transition temperature Tg), and the like can be determined using a DSC measuring apparatus.

(experimental method)
Evaluation experiments A to D were performed using a system equivalent to the ink jet recording apparatus 10 shown in FIG. 1 and appropriately changing the combination of the ink and the processing agent shown in FIGS.

  Specifically, after a treatment agent is applied to a polyimide intermediate transfer member with a film thickness of 10 μm, the treatment agent on the intermediate transfer member is dried by heating (hot air drying at 70 ° C.), and then on the intermediate transfer member. The solid or semi-solid treatment agent layer (water content 10%) is formed. Subsequently, in both the main scanning direction (direction perpendicular to the intermediate transfer body conveyance direction) and the sub-scanning direction (intermediate transfer body conveyance direction), a 2 pl ink droplet is continuously ejected at a recording density (droplet ejection density) of 1200 dpi. Thus, an ink image (primary image) composed of a solid image is formed on the intermediate transfer member. Thereafter, the ink image formed on the intermediate transfer member was transferred to a recording medium through a solvent removal step and a preheating step, and the ink image (solid image) on the recording medium was evaluated. In addition, the case where a predetermined character was drawn on the intermediate transfer member and transferred to the recording medium by the same method was also evaluated.

  Note that the conveyance speed of the intermediate transfer member was set to 640 mm / s. Further, as a recording medium, Tokuhishi Art Paper (manufactured by Mitsubishi Paper Industries Co., Ltd.) was used.

  The evaluation methods of the evaluation experiments A to D are the three viewpoints of “image disturbance due to color material movement”, “transferability”, and “non-image area gloss” for the ink image (solid image, character) transferred to the recording medium. A visual evaluation was performed.

  “Image disturbance due to movement of coloring material” is a level where there is no problem with visual observation and no problem with observation with an optical microscope. “◯”, “Δ” when the image disturbance is visually recognized, and “X” when the image disturbance is extremely unacceptable.

  “Transferability” is “◎” when the transfer rate from the intermediate transfer member to the recording medium is 100%, “◯” when it is 97% or more, “Δ” when it is 95% or more, and 95. When it was less than%, it was set as “x”.

  Regarding “non-image area glossiness”, the glossiness of the non-image area of the recording medium (art paper) is not different from the glossiness of art paper after transfer, and there is no change in texture at the visual recognition level. ◎ ”,“ ○ ”when there is no difference in glossiness of art paper and almost no change in texture at the visual recognition level,“ △ ”when an unnatural gloss is visually recognized in a part of the non-image part, A case where an unnatural gloss was visually recognized almost over the entire non-image area was defined as “x”.

(Evaluation Experiment A)
In the evaluation experiment A, the relationship between the pigment particle diameter and the surface roughness of the treatment agent layer was evaluated. The surface roughness of the treatment agent layer was measured with an ultra-deep color 3D shape measurement microscope VK-9500 (manufactured by Keyence Corporation). Further, the surface temperature of the intermediate transfer member (transfer member surface temperature) at the time of transfer was kept constant (70 ° C.). The result of the evaluation experiment A is shown in FIG.

  In FIG. 10, the comparative examples of the present invention (Experiments 1, 6, 7, and 12) are cases where the surface roughness Ra of the treatment agent layer is smaller than the pigment particle size, and image disturbance due to color material movement occurs. A favorable result could not be obtained for “image disorder” (evaluation “×” or “Δ”). This is presumably because the color material (pigment) is not fixed to the recess formed on the surface of the treatment agent layer by the solid particles.

  On the other hand, Examples (Experiments 2 to 5, 8 to 11) of the present invention are cases where the surface roughness (Ra) of the treatment agent layer is larger than the pigment particle diameter, and good results can be obtained for “image disorder”. (Evaluation “◯”) and image disturbance due to color material movement can be prevented. In addition, good results were obtained with respect to “transferability” and “non-image area gloss” (evaluation “◯” or “◎”).

  In particular, it was also confirmed that the transferability was improved when polymer fine particles were contained in the ink (Experiments 8 to 11) and when the polymer fine particles were not contained (Experiments 2 to 5).

(Evaluation Experiment B)
In the evaluation experiment B, the relationship between the melting point of the solid particles and the surface temperature of the intermediate transfer member was evaluated. The result of the evaluation experiment B is shown in FIG. In FIG. 11, the same experiment number (experiment No) is assigned to the same experiment as FIG. 10.

  In FIG. 11, the comparative examples of the present invention (Experiments 15, 18, 21, 22, 25, 26) are cases where the surface temperature of the intermediate transfer member is higher than the melting point of the solid particles, and the solid particles melt on the intermediate transfer member. As a result, good results cannot be obtained for “transferability” and “non-image area gloss” (evaluation “x” or “Δ”).

  On the other hand, Examples (Experiments 13, 3, 14, 16, 9, 17, 19, 20, 23, 24) of the present invention are cases where the surface temperature of the intermediate transfer member is lower than the melting point of the solid particles. ”Can be obtained (evaluation“ ◯ ”or“ ◎ ”), and the transferability at high speed can be improved. In addition, good results were obtained with respect to “image disorder” and “non-image area gloss” (evaluation “◯” or “）”).

(Evaluation Experiment C)
In the evaluation experiment C, the effect when the treatment agent contains two types of solid particles (first and second solid particles) or the component that aggregates the color material of the ink (color material aggregation component) is evaluated. It was. The result of the evaluation experiment C is shown in FIG. In FIG. 12, the same experiment number (experiment No) is assigned to the same experiment as FIG. 10.

  In FIG. 12, when the treatment agent contains two types of solid particles (first and second solid particles) (experiments 28, 29, 31, 32), one type of solid particles (first solid particles) As compared with the case where it is contained (Experiment 3, 27, 9, 30), it is possible to obtain a better result with respect to “image disturbance” (evaluation “）”), and to effectively prevent image disturbance due to color material movement. it can.

  Also, when the treatment agent contains a color material aggregation component (Experiments 27, 29, 30, 32), a better result can be obtained with respect to “transferability” than when the colorant aggregation component is not contained (evaluation). The transferability can be further improved by adding a color material aggregating component to the processing agent (◎).

  In particular, when the treatment agent contains two kinds of solid particles and a color material aggregation component (Experiments 29 and 32), all evaluations of “image disorder”, “transferability”, and “non-image area selection” are ◎. And very good results were obtained.

(Evaluation Experiment D)
In evaluation experiment D, the relationship between the glass transition temperature Tg of the polymer fine particles contained in the ink and the surface temperature of the intermediate transfer member (transfer member surface temperature) was evaluated. The result of the evaluation experiment D is shown in FIG. In FIG. 13, the same experiment number (experiment No.) is assigned to the same experiment as FIG.

  In FIG. 13, when the surface temperature of the intermediate transfer member is higher than the glass transition temperature Tg of the polymer particles (Experiment 9, 33, 35), when the surface temperature of the intermediate transfer member is lower than the glass transition temperature Tg of the polymer particles (Experiment 34). As a result, the transfer rate from the intermediate transfer member to the recording medium can be improved.

  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.

1 is a schematic configuration diagram of an inkjet recording apparatus according to an embodiment of the present invention. FIG. 1 is a plan view of a main part around a printing unit of the ink jet recording apparatus shown in FIG. Plane perspective view showing a configuration example of an ink head Sectional view along line 4-4 in FIG. Schematic diagram showing the configuration of the ink supply system of the ink jet recording apparatus shown in FIG. 1 is a principal block diagram showing the system configuration of the ink jet recording apparatus shown in FIG. The figure which showed the composition of ink 1a-1c The figure which showed the composition of ink 2a-2e The figure which showed the composition of the processing agents 1-8 The figure which showed the result of evaluation experiment A The figure which showed the result of evaluation experiment B The figure which showed the result of evaluation experiment C The figure which showed the result of evaluation experiment D

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Intermediate transfer body, 14 ... Recording medium, 16 ... Processing agent provision part, 18 ... Drying part, 20 ... Printing part, 22 ... Transfer part, 28 ... Solvent removal part, 30 ... Preheating part , 34 ... Cooling unit, 38 ... Fixing unit, 40 ... Cleaning unit, 50 ... Head, 51 ... Nozzle, 52 ... Pressure chamber, 58 ... Piezoelectric element, 72 ... System controller, 79 ... Transfer control unit, 80 ... Print control unit 81 ... Treatment agent application control unit

Claims (8)

Forming a solid or semi-solid treatment agent layer comprising a treatment agent containing at least one kind of solid particles on the intermediate transfer member;
In accordance with image data, forming a droplet of ink onto the surface of the treatment agent layer formed on the intermediate transfer member,
Performing image transfer from the intermediate transfer body to the recording medium in a state where the surface temperature of the intermediate transfer body is lower than the melting point of the solid particles,
The image forming method, wherein the surface roughness (Ra) of the processing agent layer formed on the intermediate transfer member is larger than a particle diameter of a color material contained in the ink. The step of forming the solid or semi-solid treatment agent layer,
Applying the treatment agent on the intermediate transfer member;
Drying the treatment agent applied on the intermediate transfer member to form a solid or semi-solid treatment agent layer comprising the treatment agent on the intermediate transfer member;
The image forming method according to claim 1, further comprising:   The image forming method according to claim 1, wherein the processing agent includes a component that aggregates the color material of the ink.   The image forming method according to claim 1, wherein the ink includes polymer fine particles.   The image forming method according to claim 4, wherein a surface temperature of the intermediate transfer member is higher than a glass transition temperature of the polymer fine particles and lower than a melting point of the solid particles. The treatment agent includes first solid particles and second solid particles having a melting point lower than that of the first solid particles,
6. The surface temperature of the intermediate transfer member is lower than the melting point of the first solid particles and higher than the melting point of the second solid particles. 6. The image forming method according to item. A treatment agent layer forming means for forming a solid or semi-solid treatment agent layer comprising a treatment agent containing at least one kind of solid particles on the intermediate transfer member;
In accordance with image data, ink droplet ejecting means for ejecting ink droplets on the surface of the treatment agent layer formed on the intermediate transfer member;
Transfer means for transferring an image from the intermediate transfer body to a recording medium in a state where the surface temperature of the intermediate transfer body is lower than the melting point of the solid particles,
The image forming apparatus, wherein the surface roughness (Ra) of the processing agent layer formed on the intermediate transfer member is larger than a particle diameter of a color material contained in the ink.   The processing agent layer forming unit is configured to dry the processing agent applied on the intermediate transfer member from the processing agent on the intermediate transfer member by drying the processing agent applied on the intermediate transfer member. 8. The image forming apparatus according to claim 7, further comprising means for forming a solid or semi-solid treatment agent layer.

Images