JP2007055084A - Imaging device/method and ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which can realize an effective two-liquid mixture (reaction) even in case a highly permeable recording medium is used, and a method using this device and an ink set. <P>SOLUTION: The imaging device (10) comprises a treating liquid supplying means (11) which supplies a treating liquid containing a polymerization initiator, an electroviscous effect-generating particle and a solvent to a recording medium (20), an electric field imparting means (28) which imparts an electric field to the treating liquid deposited on the recording medium (20), and ink discharging means (12M, 12C, 12Y and 12K) which discharge an ink containing a coloring material and an irradiation-curable polymerizable compound (16) to the surface of the recording medium (20) having the deposited treating liquid, and a radiation-irradiating means (16) which irradiates with radiations in order to cure the ink on the recording medium (20). In addition, the solvent and the particle which can generate the electroviscous effect, of the treating liquid are colorless and transparent and constituted of materials with mutually approximate index of refraction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and method, and an ink set, and more particularly to an image forming technique suitable for an ink jet recording apparatus that forms a high-quality image on a recording medium using an ink containing a color material and a treatment liquid.

  Patent Document 1 discloses an ink jet recording method in which a reaction liquid contains a photopolymerization initiator and an ink composition contains an acrylate monomer. Patent Document 2 includes a unit that discharges recording ink toward a recording member (recording medium), and a processing liquid unit that discharges processing liquid toward the recording ink discharged by the unit. In the inkjet recording apparatus, the recording ink and the treatment liquid are mixed and cured to form at least a part of the image.

In Patent Document 3, the ink composition contains a polymerizable compound and a coloring material, the content of the polymerizable compound in the ink composition is 30 to 98% by mass, and the reaction liquid contains the polymerizable compound and the polymerization initiator. An ink jet recording method characterized by containing it is disclosed.
JP-A-10-287035 JP 2000-135781 A JP 2003-12971 A

  Patent Documents 1 to 3 disclose a technique for separating an ultraviolet curable ink (so-called UV ink) into a two-component structure. However, when the recording medium has high permeability and the first solution penetrates quickly, There is a problem that the effect of the treatment liquid function due to the penetration of the treatment liquid is lost (or reduced). For such problems, Patent Documents 1 to 3 do not present a method for effectively mixing two liquids.

  The present invention has been made in view of such circumstances, and an image capable of forming a high-quality image by realizing effective mixing (reaction) of two liquids even when a highly permeable recording medium is used. An object is to provide a forming apparatus and method, and an ink set.

  In order to achieve the above object, an image forming apparatus according to the invention of claim 1 includes a processing liquid applying means for applying a processing liquid containing a polymerization initiator, particles exhibiting an electrorheological effect, and a solvent to a recording medium. An electric field applying means for applying an electric field to the treatment liquid attached on the recording medium; and an ink containing a coloring material and a radiation curable polymerizable compound is ejected onto the recording medium to which the treatment liquid is attached. An ink ejecting means for irradiating and radiation irradiating means for irradiating radiation for curing the ink on the recording medium, and the solvent in the treatment liquid and the particles exhibiting the electrorheological effect are both colorless. It is characterized by being made of transparent materials having refractive indexes close to each other.

  According to the present invention, before the ink is deposited on the recording medium, the treatment liquid (pretreatment liquid) is deposited on the recording medium, and an electric field is applied to the processing liquid on the recording medium. The treatment liquid becomes highly viscous due to the electroviscous effect, and the penetration into the recording medium is suppressed (the penetration speed into the recording medium is reduced). Thus, by ejecting the ink with the treatment liquid sufficiently remaining on the recording medium, reliable mixing of the two liquids can be realized, and the mixed liquid is cured and fixed by radiation irradiation. High quality image formation can be realized. That is, due to the increase in the viscosity of the treatment liquid due to the electrorheological effect, the penetration of the treatment liquid into the recording medium (particularly a highly permeable medium) can be suppressed, and the loss of the effect of the treatment liquid function due to the penetration of the treatment liquid on the recording medium can be prevented can do. Moreover, diffusion of the coloring material in the processing liquid can be suppressed by increasing the viscosity of the processing liquid due to the electrorheological effect.

  Furthermore, in the present invention, as the solvent of the treatment liquid and the electroviscous effect (ER effect) manifesting particles, both the colorless and transparent materials having refractive indices close to each other are selected, thereby preventing the treatment liquid from becoming clouded. The liquid can be made colorless and transparent. Thereby, the color of the ink can be faithfully reproduced, and the deterioration of the image quality can be prevented.

  Further, after the ink is adhered, the curing reaction is advanced by irradiation of radiation, so that curing and fixing can be performed in a short time, and high-speed printing can be realized. Examples of radiation include visible light, ultraviolet rays, electromagnetic waves such as X-rays, and electron beams.

  In the application of an electric field for expressing the electrorheological effect of the treatment liquid, it is more preferable to perform a control for applying a necessary minimum electric field capable of suppressing the penetration of the treatment liquid. Accordingly, it is possible to prevent an increase in the viscosity of the processing liquid in the head when an ink jet type liquid discharge head is applied as the processing liquid application unit.

  As an example of the electric field applying means for expressing the electrorheological effect, it has a structure in which an electrode pair composed of a first electrode and a second electrode is disposed, and is relative to the first electrode and the second electrode. When a potential difference is given (that is, when a voltage is applied), there is a mode in which a predetermined electric field strength is generated in the peripheral portion of the electrode pair. In such an embodiment, the electrode pair consisting of the first electrode and the second electrode includes both positive and negative electrodes, one electrode having a positive potential and the other electrode having a negative potential. Also included are electrode pairs that are positive or negative.

  The electric field applying means can also be used as electrostatic adsorption means for stably holding the recording medium by electrostatic force. In other words, an electric field can be applied to the processing liquid on the recording medium by using an electric field of an electrostatic adsorption unit (for example, a belt or a roller) that holds the recording medium.

  As other aspects of the electric field applying means, (a) an aspect in which the processing liquid is sandwiched by plate electrodes having a high potential difference, (b) charging and recording of the recording medium and the processing liquid by a conductive rubber roller, a conductive brush, corona discharge, etc. A combination of electrodes disposed in the vicinity of the medium, (c) a combination of charging of the recording medium and the processing liquid by electron beam irradiation or ion irradiation to the recording medium or the processing liquid on the recording medium and an electrode disposed in the vicinity of the recording medium, (d ) There are various modes such as a combination of charging of a droplet (treatment liquid droplet) itself by passage of an electric field of a flying droplet and an electrode disposed in the vicinity of a recording medium.

  2. The image forming apparatus according to claim 1, wherein the liquid permeability and the behavior of the landing droplet on the recording medium differ depending on conditions such as the material, thickness and dielectric constant of the recording medium. It is preferable that the recording medium type specifying unit to be specified and an electric field control unit for controlling the electric field by the electric field applying unit according to the type of the recording medium specified by the recording medium type specifying unit.

  The type of recording medium is grasped using the recording medium type specifying means, and an electric field such as applied (ON) / non-applied (OFF) of the electric field, or the electric field strength at the time of application, or a combination thereof is determined according to the medium type. By appropriately controlling, printing under optimum conditions corresponding to the recording medium can be performed.

  For example, when a medium with high permeability (penetration medium) is used, an electric field is applied to suppress the penetration of the treatment liquid, while a medium with low permeability (non-penetration medium or low penetration medium) is used. Does not apply an electric field.

  It is more preferable that the means for controlling the electric field strength at the time of application is a configuration in which the electric field strength is automatically adjusted from the information obtained by the recording medium type specifying means. A configuration in which the electric field intensity is switched or changed is also possible.

  The recording medium type specifying means includes, for example, means for measuring the reflectance of the recording medium, means for reading the type of recording medium used from the ID of the supply magazine, and the like. The recording medium type specifying means is not limited to a form in which information is automatically acquired by a sensor, an information reading means, or the like, but a user inputs information such as the paper type of the recording medium by a predetermined input device (user interface) or the like. A configuration is also possible in which the input is performed by operating.

  The processing liquid application means in the image forming apparatus of the present invention includes, for example, a means for discharging the processing liquid as droplets using an ink jet type liquid discharge head (by ejection from an ink jet nozzle), a roller, a brush, a blade shape, etc. There are modes such as means for applying the processing liquid using a member, a porous member, etc., means for spraying and adhering the processing liquid in a spray form, or an appropriate combination thereof.

  As the ink discharge means, an ink jet type liquid discharge head that discharges ink liquid based on image information for drawing (print data) is preferably used.

A second aspect of the present invention is an aspect of the image forming apparatus according to the first aspect, wherein the processing liquid contains a color material diffusion preventing agent for preventing the color material from diffusing.
By mixing the treatment liquid and the ink in this manner, it is possible to reliably prevent the color material from diffusing on the recording medium and to prevent bleeding.

  The invention according to claim 3 is an aspect of the image forming apparatus according to claim 1 or 2, and an average particle diameter of the particles exhibiting the electrorheological effect in the processing liquid is 0.3 μm to 10 μm. The treatment liquid applying means is a coating means for applying the treatment liquid while being in contact with the recording medium.

  When the average particle diameter of the ER effect-expressing particles dispersed in the treatment liquid is 0.3 μm to 10 μm, from the viewpoint of the liquid physical properties of the treatment liquid, it is preferable to use a roller or the like rather than ejecting droplets by an ink jet method. An embodiment in which application is performed using an application member is easy. Moreover, since there is no restriction | limiting by the viewpoint of the discharge appropriateness by an inkjet system, and the particle | grain of the comparatively big particle diameter suitable for expression of an electrorheological effect can be utilized, sufficient electrorheological effect can be expressed.

  Further, by using a radiation effect type polymerizable compound as a solvent for the treatment liquid, there is an advantage that the treatment liquid applied to the non-image area can also be cured.

  The invention according to a fourth aspect is an aspect of the image forming apparatus according to the first or second aspect, wherein an average particle diameter of the particles exhibiting the electrorheological effect in the processing liquid is 100 nm to 1 μm, and The treatment liquid applying means is a discharge means for discharging the treatment liquid as droplets by an ink jet method.

  When the average particle diameter of the ER effect-expressing particles dispersed in the treatment liquid is 100 nm to 1 μm, the liquid physical properties of the treatment liquid can be suitable for ejecting droplets by the inkjet method. It is possible to select a mode in which the treatment liquid is adhered by the discharge means. According to this aspect, since the processing liquid can be selectively applied only to a necessary portion on the recording medium, it is possible to reduce wasteful consumption of the processing liquid as compared with the application unit.

  A fifth aspect of the present invention is an aspect of the image forming apparatus according to any one of the first to fourth aspects, wherein the processing liquid tank that stores the processing liquid to be supplied to the processing liquid applying unit; And a stirring means for stirring the processing liquid in the processing liquid tank.

  Agitation means is provided in the treatment liquid tank as a means for storing the treatment liquid, and the treatment liquid in the treatment liquid tank is agitated by the agitation means, thereby suppressing aggregation and sedimentation of dispersed particles in the treatment liquid. And the storage stability of the treatment liquid can be improved.

  An ink jet recording apparatus as one aspect of an image forming apparatus of the present invention is a liquid droplet ejection device including a nozzle for ejecting ink droplets for forming dots and pressure generating means (such as a piezoelectric element and a heating element) for generating ejection pressure. A liquid discharge head (corresponding to a “recording head”) having a droplet discharge element array in which a plurality of elements are arranged, and droplets from the recording head based on droplet placement data (dot data) generated from image data An ejection control means for controlling ejection, and an image is formed on a recording medium by droplets ejected from the nozzle.

  As a configuration example of the recording head (ink discharge means), a full line type head in which a plurality of nozzles are arranged over a length corresponding to the entire width of the recording medium can be used. In this case, a plurality of relatively short recording head modules having nozzle rows that do not have a length corresponding to the entire width of the recording medium are combined, and the nozzles having a length corresponding to the entire width of the recording medium as a whole are connected. There is an aspect that constitutes a column.

  A full-line type head is usually arranged along a direction perpendicular to the relative feeding direction (relative conveyance direction) of the recording medium, but has a certain angle with respect to the direction perpendicular to the conveyance direction. There may be a mode in which the recording head is arranged along the oblique direction.

  The “recording medium” is a medium to which liquid ejected from a liquid ejection head (recording head) adheres, and receives an image recording by the action of the recording head. That is, the “recording medium” can be called a printing medium, an image forming medium, a recording medium, an image receiving medium, an ejected medium, and the like, a continuous sheet, a cut sheet, a seal sheet, a resin sheet such as an OHP sheet, Various media are included regardless of the material and shape, such as a printed board on which a film, cloth, wiring pattern, or the like is formed, an intermediate transfer medium, and the like.

  “Conveyance means” means a mode in which the recording medium is transported to a stopped (fixed) recording head, a mode in which the recording head is moved relative to the stopped recording medium, or a movement of both the recording head and the recording medium Any of the embodiments are included.

  When a color image is formed by an inkjet head, a recording head may be arranged for each color of a plurality of colors (recording liquids), or a configuration in which a plurality of colors of ink can be discharged from one recording head may be adopted. .

  The present invention is not limited to the full-line head described above, but can also be applied to shuttle scan type recording heads (recording heads that perform droplet ejection while reciprocating in a direction substantially perpendicular to the recording medium conveyance direction). It is.

  The invention according to claim 6 provides a method invention for achieving the object. That is, the image forming method according to claim 6 includes a polymerization initiator, particles exhibiting an electrorheological effect, and a solvent, and the solvent and the particles are both colorless and transparent, and have a refractive index approximate to each other. A treatment liquid application step for applying a treatment liquid to the recording medium, an electric field application step for applying an electric field to the treatment liquid attached on the recording medium, and a color on the recording medium to which the treatment liquid is attached. An ink discharge step of discharging an ink containing a material and a radiation curable polymerizable compound; and a radiation irradiation step of irradiating with radiation for curing the ink on the recording medium. .

  The invention according to claim 7 provides an ink set that achieves the object. That is, the ink set according to claim 7 includes a polymerization initiator, particles exhibiting an electrorheological effect, and a solvent, and the solvent and the particles are both colorless and transparent, and are composed of materials having refractive indexes close to each other. And an ink containing a coloring material and a radiation curable polymerizable compound.

  According to the present invention, it is possible to leave the treatment liquid on the medium due to the electrorheological effect even for a highly permeable medium, and the two liquids can be reliably mixed regardless of the type of recording medium. Become. Thereby, high-quality image formation can be realized. In addition, in the composition of the treatment liquid, the solvent and the dispersed fine particles (particles exhibiting the electroviscous effect) are both colorless and transparent, and a material having a refractive index close to each other is selected. The treatment liquid can be made transparent. Thereby, the color of the ink can be faithfully reproduced.

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

[First Embodiment: Overall Configuration of Inkjet Recording Apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus showing a first embodiment of an image forming apparatus according to the present invention. As shown in the figure, the inkjet recording apparatus 10 includes a treatment liquid application mechanism 11 (corresponding to “treatment liquid application means”) for applying a first treatment liquid (pretreatment liquid), magenta ( M), cyan (C), yellow (Y), black (K) corresponding to a plurality of ink ejection heads (corresponding to “ink ejection means”) provided corresponding to each color ink (second liquid) Hereinafter referred to as “ink heads”) 12M, 12C, 12Y, 12K, a processing liquid tank 13 for storing the processing liquid supplied to the processing liquid coating mechanism 11, and the ink heads 12M, 12C, 12Y, An ink storage / loading unit 14 that stores color ink to be supplied to 12K, an ultraviolet light source (corresponding to “radiation irradiation unit”, hereinafter referred to as “UV light source”) 16 as a fixing promoting unit, and a recording medium 20 Supply media supply 22, a decurling unit 24 for removing the curl of the recording medium 20, a media type detecting unit 25 (corresponding to “recording medium type specifying means”) for detecting the type of the recording medium 20, and each head 12 M, 12 C, 12 Y. , 12K ejection surface (nozzle surface) and the light emitting surface of the UV light source 16, and a conveyance unit 26 that conveys the recording medium while maintaining the flatness of the recording medium 20, and an attachment to the conveyance unit 26 And an electrode unit 28 (corresponding to “electric field applying means”) for applying an electric field to the liquid on the recording medium 20.

  The treatment liquid application mechanism 11 is immersed in the application roller 31 that contacts the recording medium 20, the treatment liquid supply roller 32 that circumscribes the application roller 31 and supplies the treatment liquid to the application roller 31, and the treatment liquid supply roller 32. And a container (immersion container) 33 for holding the treatment liquid to be made.

  The processing liquid tank 13 supplies the processing liquid to the immersion container 33 through a required pipe line 35T. The processing liquid tank 13 includes notifying means (display means, warning sound generating means) for notifying when the remaining amount of processing liquid is low, and has a mechanism for preventing erroneous loading between liquid types. Yes. Further, in order to prevent aggregation and settling of the dispersed fine particles contained in the processing liquid, a stirring blade 36 as a stirring means is provided in the processing liquid tank 13. Details of the composition of the treatment liquid will be described later.

  The ink storage / loading unit 14 includes ink tanks 14M, 14C, 14Y, and 14K that store inks of colors corresponding to the ink heads 12M, 12C, 12Y, and 12K. The heads 12M, 12C, 12Y, and 12K communicate with each other through 35C, 35Y, and 35K. Further, the ink storage / loading unit 14 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.

  In the present embodiment, an electrorheological fluid having an electrorheological effect is used as the first treatment liquid. The electrorheological fluid is a liquid whose apparent viscosity instantaneously increases when an electric field is applied (voltage application), and the viscosity reversibly changes when the electric field is turned on / off. There are two types of such electrorheological fluids, a dispersion type and a homogeneous system.

  In the dispersion type, dielectric fine particles are dispersed in a liquid in an electrically insulating solvent. When no electric field is applied, the fine particles remain dispersed and the viscosity is low. When the is added, the polarized particles form a chain structure (bridge) connected in the direction of the electric field, and this bridge acts to increase the viscosity of the fluid, so that the behavior of the fluid increases in viscosity. . Dispersed electrorheological fluids include a hydrous system and a non-hydrous system.

  The homogeneous system is an anisotropy in which molecules and domains are aligned in the electric field direction, such as liquid crystal. Since uniform electrorheological fluids have little change in viscosity at present, it is considered that distributed electrorheological fluids are suitable for inkjet printer applications.

  In this embodiment, the treatment liquid has an electrorheological effect. For example, as a method for producing such a treatment liquid, solid fine particles (starch, acrylic acid polymer, Dispersion of electro-viscous effect by dispersing the cellulose (silica, silica, dextrin, carbon, gypsum, gelatin, alumina, mica, zeolite, kaolinite, etc.) and insulating the surface of the microparticles (microencapsulated particles, etc.) The method of using as an agent, the method of mixing a homogeneous electrorheological fluid, etc. can be considered.

  Here, as the first treatment liquid, “polymerization initiator, colorant diffusion inhibitor, oil as a high-boiling organic solvent, and particles exhibiting an electrorheological effect (hereinafter referred to as“ ER effect-expressing particles ”). A transparent treatment liquid (containing no color material) having a liquid composition containing “

  Here, although a high boiling point organic solvent (oil) is used as a solvent, a radiation curable monomer or oligomer may be used as a solvent instead.

  The solvent and the ER effect-expressing particles are both colorless and transparent and have similar refractive indexes. According to experimental findings, in order to ensure the transparency of the treatment liquid, the difference in refractive index between the solvent and the ER effect-expressing particles is preferably within 0.1, more preferably within 0.05.

  Examples of combinations include, for example, diethyl phthalate (refractive index = 1.505) as a processing liquid oil, or HDDA (hexanediol diaurate; refractive index = 1.456) as a monomer liquid, and ER. There are combinations using silica (refractive index = 1.46) or mica (refractive index = 1.56) as the effect-expressing particles.

  In addition, as a second ink, a liquid ink containing “ultraviolet curable polymerizable compound (monomer, oligomer, etc.) and a pigment as a coloring material” is used for the number of colors (in this example, C, M , Y, K). The details of the ink set used in this embodiment will be described later.

  When the ink and the processing liquid are mixed, the coloring material diffusion inhibitor in the processing liquid suppresses the diffusion of the coloring material between the landed dots, and the polymerization reaction of the liquid is caused by mixing the two liquids and irradiating the mixed liquid with ultraviolet rays. Progresses and hardens.

  It is possible to adjust the curing speed and physical properties (surface tension, viscosity, etc.) of each liquid by adjusting the composition and component concentration of the ink and the processing liquid, and the desired ink fixing properties (curing speed, Fixing speed, etc.) can be realized.

  In FIG. 1, a roll paper (continuous paper) magazine 23 is shown as an example of the media supply unit 22, but a plurality of magazines having different paper widths, paper qualities, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  The recording medium 20 delivered from the media supply unit 22 retains curl due to having been loaded in the magazine 23. In order to remove the curl, heat is applied to the recording medium 20 by the heating drum 37 in the direction opposite to the curl direction of the magazine 23 in the decurling unit 24. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration using roll paper, as shown in FIG. 1, a cutter 38 is provided, and the roll paper is cut into a desired size by the cutter 38. The cutter 38 includes a fixed blade 38A having a length equal to or greater than the conveyance path width of the recording medium 20 and a round blade 38B that moves along the fixed blade 38A. The fixed blade 38A is provided on the back side of the print. The round blade 38B is arranged on the print surface side with the conveyance path interposed therebetween. Note that the cutter 38 is not necessary when cut paper is used.

  After the decurling process, the cut recording medium 20 is sent to the transport unit 26. A media type detection unit 25 is installed at an appropriate location in the conveyance path of the recording medium 20 in the preceding stage (upstream side of the recording medium conveyance path) of the processing liquid coating mechanism 11. The media type detection unit 25 is a means for acquiring information on the media type, and is a means for detecting the paper type, wettability, size, etc. of the recording medium 20 (for example, a sensor for detecting the optical reflectance of the paper, a paper width, etc. A detection sensor, a sensor for detecting the thickness of the paper, or an appropriate combination thereof). The media type detection unit 25 automatically determines the type of the recording medium 20 and performs control so as to realize appropriate treatment liquid application, electric field control, and ink ejection according to the media type.

  Note that the means for acquiring information about the media type is not limited to the above configuration. For example, an information recording body such as a bar code or a wireless tag in which media type information is recorded is attached to the magazine 23 of the media supply unit 22, and information on the information recording body is read by a predetermined reader (information reading means). A configuration for automatically determining the type of media to be used is also possible. Further, instead of or in combination with these automatic detection means, it is also possible to specify recording medium information such as paper type, wettability, and size by input from a predetermined user interface.

  The transport unit 26 has a structure in which an endless slightly conductive belt 43 is wound between rollers 41 and 42, at least a portion facing the coating roller 31 of the treatment liquid coating mechanism 11, and the heads 12 </ b> M, 12 </ b> C, The part which opposes the 12Y and 12K nozzle surfaces is configured to form a horizontal surface (flat surface).

  The slightly conductive belt 43 has a width that is greater than the width of the recording medium 20, and the electrode unit 28 is disposed on the back side of the portion that holds the recording medium 20. Although details will be described later, when a high DC voltage is applied to the electrode unit 28 by a DC high voltage generator (not shown in FIG. 1, described as reference numeral 78 in FIG. 7), the recording medium 20 is slightly conductive by electrostatic force. It is sucked and held on the belt 43 and an electric field is applied to the landing treatment liquid and the landing ink on the recording medium 20.

  When the power of the motor (not shown in FIG. 1, described as reference numeral 138 in FIG. 9) is transmitted to at least one of the rollers 41 and 42 around which the slightly conductive belt 43 is wound, the slightly conductive belt 43 is 1 is driven counterclockwise, and the recording medium 20 is conveyed from right to left in FIG.

  The application roller 31 is made of, for example, a member such as rubber, and has a structure in which the processing liquid is poured onto the recording medium 20 along the peripheral surface of the application roller 31 while rotating the application roller 31 in a predetermined direction. ing.

  The application roller 31 may have a length corresponding to the entire width of the recording medium 20 by a single (single) long roller member, or a direction (mainly perpendicular to the conveyance direction of the recording medium 20). It may be divided into a plurality of roller modules along the scanning direction, and these may be arranged to achieve a required length. A configuration in which a plurality of rows of application rollers are arranged along the conveyance direction of the recording medium 20 is also possible.

  Although not shown in FIG. 1, a vertical mechanism for moving the application roller 31 up and down with respect to the recording medium 20 is provided. By controlling the vertical mechanism according to a command from the system control system and adjusting the height position of the application roller 31 (relative position in the direction perpendicular to the recording surface of the recording medium 20), the contact pressure to the recording medium 20 In addition, the clearance with the recording medium 20 can be varied. In the case of a configuration having a plurality of roller modules, it is preferable to provide a mechanism for controlling the vertical position of each roller module.

  Each of the ink heads 12M, 12C, 12Y, and 12K has a length corresponding to the maximum paper width of the recording medium 20 targeted by the inkjet recording apparatus 10, and at least the maximum size of the recording medium 20 is formed on the nozzle surface. The head is a full-line type in which a plurality of nozzles (discharge ports) are arranged over a length exceeding one side (full width of the drawable range).

  The ink heads 12M, 12C, 12Y, and 12K are arranged in the order of magenta (M), cyan (C), yellow (Y), and black (K) from the upstream side along the feeding direction of the recording medium 20, respectively. The ink heads 12M, 12C, 12Y, and 12K are fixedly installed so as to extend along a direction substantially orthogonal to the conveyance direction of the recording medium 20.

  A color image can be formed on the recording medium 20 by ejecting different colors of ink from the respective ink heads 12M, 12C, 12Y, and 12K while the recording medium 20 is being conveyed at a constant speed by the conveying unit 26.

  As described above, according to the configuration in which the full-line heads 12M, 12C, 12Y, and 12K having nozzle rows that cover the entire width of the paper are provided for each color, the recording medium 20 is moved to the head 12M in the paper feeding direction (sub-scanning direction). , 12C, 12Y, and 12K, the image can be recorded on the entire surface of the recording medium 20 by performing the operation of moving relative to the recording medium 20 only once (that is, by one sub-scanning). Such a single-pass inkjet recording apparatus 10 can perform high-speed printing as compared with a shuttle scan system that performs drawing while reciprocating the recording head in the main scanning direction, and can improve print productivity.

  In this example, the configuration of MCYK 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, special color ink, etc. are used as necessary. May be added. For example, it is possible to add a head for ejecting light-colored ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

  The UV light source 16 arranged at the rear stage of the final color ink head 12K has a length corresponding to the maximum paper width of the recording medium 20 in the same manner as the heads 12M, 12C, 12Y, and 12K. It is installed so as to extend in a direction substantially orthogonal to the conveying direction. For example, an ultraviolet lamp is used as the UV light source 16 and irradiates ultraviolet rays for promoting the curing of the landing ink on the recording medium 20. Instead of the ultraviolet lamp, a configuration in which ultraviolet LED elements or ultraviolet LD elements are arranged in a line shape may be used. According to such a configuration, since it is possible to selectively control light emission for each light emitting element, the number of light emitting elements to be turned on and the amount of emitted light can be easily adjusted, and a desired irradiation range and light intensity (intensity) distribution can be obtained for an ultraviolet irradiation area. realizable.

  Note that the UV light source 16 is not necessarily required until the ink ejected onto the recording medium 20 is completely cured (fixed) and cured. However, when passing through the UV light source 16, it is preferable that the curing / fixing has progressed to such an extent that image degradation does not occur due to subsequent handling (in the downstream process). Handling here refers to [1] rubbing between the roller, transport guide, etc. and the image surface in the downstream transport process of the radiation irradiating means, [2] rubbing between prints in the print stacking unit, and [3] finished print. It means rubbing by various objects when actually handled.

  Thus, the recording medium 20 (generated printed matter) that has passed through the UV light source 16 is discharged from the paper discharge section via a toothed driven roller and a nip roller (not shown). Although not shown in FIG. 1, the paper discharge unit is provided with a sorter for collecting images according to orders.

  The electrode unit 28 attached to the transport unit 26 is disposed in an area range including at least a treatment liquid adhesion start position by the application roller 31 and an ultraviolet irradiation position by the UV light source 16, and generates an electric field in the area. be able to.

[Head structure]
Next, the structure of the ink heads 12M, 12C, 12Y, and 12K will be described. Since the structure of each head provided for each ink color is common, the head for ink will be represented by reference numeral 50 in the following.

  FIG. 2A is a plan perspective view showing an example of the structure of the ink head 50, and FIG. 2B is an enlarged view of a part thereof. In order to increase the dot pitch printed on the recording medium 20, it is necessary to increase the nozzle pitch in the ink head 50. As shown in FIGS. 2 (a) and 2 (b), the ink head 50 of this example is an ink chamber unit comprising a nozzle 51 as an ink droplet ejection port, a pressure chamber 52 corresponding to each nozzle 51, and the like. It has a structure in which (droplet discharge elements) 53 are arranged in a zigzag matrix (two-dimensionally), and is thereby projected so as to be arranged along the head longitudinal direction (direction perpendicular to the paper feed direction). High density of substantial nozzle interval (projection nozzle pitch) is achieved.

  A configuration in which nozzle rows having a length corresponding to the full width Wm of the recording medium 20 are configured in a direction (arrow M direction; main scanning direction) substantially orthogonal to the feeding direction (arrow S direction; sub-scanning direction) of the recording medium 20. Is not limited to this example. For example, instead of the configuration of FIG. 2 (a), as shown in FIG. 3, a short head unit 50 'in which a plurality of nozzles 51 are two-dimensionally arranged is arranged in a staggered manner and connected to form a recording medium. You may comprise the line head which has a nozzle row of the length corresponding to the full width of 20.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape (see FIGS. 2 (a) and 2 (b)), and is connected to the nozzle 51 at both corners on a diagonal line. An outlet and an inlet (supply port) 54 for supply ink are provided. The shape of the pressure chamber 52 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon and other polygons, a circle, and an ellipse.

  FIG. 4 is a cross-sectional view (a cross-sectional view taken along line 4-4 in FIG. 2A) showing a three-dimensional configuration of a droplet discharge element for one channel (an ink chamber unit corresponding to one nozzle 51). is there. As shown in FIG. 4, each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common channel 55 communicates with an ink tank (not shown in FIG. 4, not shown in FIG. 6 and indicated by reference numeral 60) serving as an ink supply source, and the ink supplied from the ink tank 60 passes through the common channel 55 in FIG. Then, it is distributed and supplied to each pressure chamber 52.

  An actuator 58 having an individual electrode 57 is joined to a pressure plate (vibrating plate that also serves as a common electrode) 56 constituting a part of the pressure chamber 52 (the top surface in FIG. 4). By applying a drive voltage between the individual electrode 57 and the common electrode, the actuator 58 is deformed and the volume of the pressure chamber 52 is changed, and ink is ejected from the nozzle 51 due to the pressure change accompanying this. The actuator 58 is preferably a piezoelectric element using a piezoelectric material such as lead zirconate titanate or barium titanate. After the ink is ejected, when the displacement of the actuator 58 returns to its original state, new ink is refilled into the pressure chamber 52 from the common channel 55 through the supply port 54.

  As shown in FIG. 5, the ink chamber unit 53 having such a structure is latticed in a fixed arrangement pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape.

That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain 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, a high-density nozzle array can be realized.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and the nozzles are sequentially driven from one side to the other for each block, etc., and one line (1 in the width direction of the paper (direction perpendicular to the paper conveyance direction)) Driving a nozzle that prints a line of dots in a row or a line consisting of dots in a plurality of rows is defined as main scanning.

  In particular, when driving the nozzles 51 arranged in a matrix as shown in FIG. 5, the main scanning as described in (3) above is preferable. That is, nozzles 51-11, 51-12, 51-13, 51-14, 51-15, 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, Nozzles 51-31,..., 51-36 as one block,..., And the recording media 20 by sequentially driving the nozzles 51-11, 51-12,. One line is printed in the width direction of 20.

  On the other hand, by relatively moving the above-mentioned full line head and the paper, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the above-described main scanning is repeatedly performed. This is defined as sub-scanning.

  The direction indicated by one line (or the longitudinal direction of the belt-like region) recorded by the main scanning is referred to as a main scanning direction, and the direction in which the sub scanning is performed is referred to as a sub scanning direction. That is, in the present embodiment, the transport direction of the recording medium 20 is the sub-scanning direction, and the direction orthogonal to the recording medium 20 is the main scanning direction.

  In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example. In the present embodiment, a method of ejecting ink droplets by deformation of an actuator 58 typified by a piezo element (piezoelectric element) is adopted. However, in the practice of the present invention, the method of ejecting ink is not particularly limited. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

[Configuration of ink supply system]
FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. The ink tank 60 is a base tank that supplies ink to the ink head 50 and is installed in the ink storage / loading unit 14 described with reference to FIG. That is, the ink tank 60 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. In the form of the ink tank 60, there are a system that replenishes ink from a replenishing 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. 6, a filter 62 is provided between the ink tank 60 and the ink head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter. Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the ink head 50 or integrally with the ink 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 nozzle surface 50A. . The maintenance unit (recovery means) including the cap 64 and the cleaning blade 66 can be moved relative to the ink head 50 by a moving mechanism (not shown), and can be moved from a predetermined retraction position to a position below the ink head 50 as required. Moved to the maintenance position.

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

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

  During printing or standby, when a specific nozzle is used less frequently and the ink viscosity near the nozzle increases or the ink is deteriorated, a cap 64 (also used as an ink receiver) is used to discharge the deteriorated ink. Preliminary discharge is performed toward the front.

  If the ink head 50 is not ejected for a certain period of time, the viscosity of the ink in the vicinity of the nozzle becomes high, and the ink cannot be ejected from the nozzle 51 even when the ejection driving actuator 58 is operated. Therefore, before this state is reached (within the range of viscosity at which ink can be discharged by the operation of the actuator 58), the actuator 58 is operated toward the ink receiver to discharge the ink in the vicinity of the nozzle whose viscosity has increased. "Preliminary discharge" is performed. In addition, after the dirt on the surface of the nozzle plate is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, the foreign matter is prevented from entering the nozzle 51 by the wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  On the other hand, if bubbles are mixed into the nozzle 51 or the pressure chamber 52 or if the viscosity of the ink in the nozzle 51 rises above a certain level, ink cannot be ejected by the preliminary ejection. In such a case, the cap 64 serving as a suction means is brought into contact with the nozzle surface 50A of the ink head 50, and the ink in the pressure chamber 52 (ink mixed with bubbles or thickened ink) is sucked by the suction pump 67. Ink removed by the suction operation is sent to the collection tank 68. The ink collected in the collection tank 68 may be reused, or may be discarded if it cannot be reused.

  Since the above suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible. The above suction operation is also performed when the ink is initially loaded into the ink head 50, or at the start of use after a long stop.

[Structure of electrode unit]
FIG. 7 is a plan view showing an example of an electrode arrangement structure of the electrode unit 28 described in FIG. As shown in FIG. 7, the electrode unit 28 includes a rod-like positive electrode 72 and a negative electrode 74 that are substantially parallel to a direction orthogonal to the conveyance direction (arrow S direction) of the recording medium 20. It consists of a structure in which a large number are alternately arranged at intervals of a distance wp. In FIG. 7, for convenience of drawing, the number of electrodes is reduced and schematically shown. However, actually, a large number of electrodes are densely arranged.

  The rod-like positive electrode 72 and negative electrode 74 are each formed with a dimension WL longer than the width dimension Wm of the recording medium 20 in order to give a uniform electric field to the landing treatment liquid on the recording medium 20.

  The electrode unit 28 has positive and negative electrode pattern pairs 72-1, 74-1 and is connected to a DC high voltage generator 78 via switches SW11, SW12. The positive electrode pattern 72-1 has a comb-like shape in which one ends (upper ends in FIG. 7) of the plurality of rod-like positive electrodes 72-1a are connected to a common base electrode portion 72-1b. Similarly, the negative electrode pattern 74-1 has a comb-like shape in which one ends (lower ends in FIG. 7) of the plurality of rod-like negative electrodes 74-1a are connected to a common base electrode portion 74-1b. The positive electrode pattern 72-1 and the negative electrode pattern 74-1 are arranged so that the rod-shaped electrode portions opened in a comb shape face each other. The positive base electrode part 72-1b is connected to the positive electrode of the DC high voltage generator 78 via the switch SW11. The negative proximal electrode portion 74-1b is connected to the negative electrode of the DC high voltage generator 78 via the switch SW12. By controlling the switches SW11 and SW12, voltage application (ON) / non-application (OFF) can be controlled.

  A cross-sectional view taken along line 8-8 in FIG. 7 is shown in FIG. As shown in FIG. 8, the electrode unit 28 is disposed under the slightly conductive belt 43 that supports the recording medium 20. The electrode unit 28 has a layer structure in which an electrode layer 82 is disposed on an insulating support layer 80. In the electrode layer 82, the positive and negative electrodes 72 and 74 described in FIG. 7 are formed in the same plane. The space between the electrodes 72 and 74 in the electrode layer 82 is filled with an insulating material 84 and is electrically insulated.

  The slightly conductive belt 43 covers the upper layer of the electrode unit 28 and is in contact with the back surface of the recording medium 20. The electrical resistivity of the fine conductive belt 43 is preferably about 10 8 to 10 12 Ωcm. Further, the thickness of the slightly conductive belt 43 is preferably about 0.01 mm to 10 mm.

  Since the slightly conductive belt 43 covers the surface of the electrode layer 82 on the recording medium 20 side, it serves to protect the positive and negative electrodes 72 and 74 and prevents harm to the human body such as electric shock. Further, the slightly conductive belt 43 prevents the belt from being kept charged when the printing operation is not performed, such as when the power is turned off.

When a predetermined voltage is applied between the electrodes 72 and 74 from the DC high voltage generator 78 shown in FIG. 7, an electric field is generated between the adjacent electrodes 72 and 74 as shown in FIG. Electric field lines 86 of the electric field generated at this time are indicated by a two-dot chain line in FIG. As shown in the drawing, the electric field lines 86 formed between the electrodes 72 and 74 adjacent to each other have a substantially arc shape, and an electric field is also generated above the print surface of the recording medium 20. As a result, an electric field is applied to the processing liquid 88 on the recording medium 20. At this time, a minute current flows in the processing liquid 88 on the recording medium 20 via the fine conductive belt 43 and the recording medium 20. In this way, an electroviscous effect appears in the processing liquid 88 on the recording medium 20, and the viscosity of the processing liquid 88 increases. While the electric field is continuously applied, the thickened state by the electrorheological effect is maintained. Thereby, the processing liquid 88 is maintained in a liquid state, and permeation into the recording medium 20 and permeation bleeding are suppressed.

  In the present embodiment, the strength of the electric field applied on the recording medium 20 depends on the interelectrode distance Wp between the positive electrode 72 and the negative electrode 74 arranged adjacent to each other and the applied voltage between the electrodes. If the applied voltage is constant, the electric field strength on the recording medium 20 increases as the interelectrode distance Wp decreases. Therefore, from the viewpoint of keeping the applied voltage low, the interelectrode distance Wp is preferably small and more preferably about 0.1 to 20 mm.

  Further, as the thickness (electrode width) Ws of each of the electrodes 72 and 74 is thinner, the intensity distribution of the electric field formed on the recording medium 20 becomes substantially uniform (substantially uniform). Therefore, the electrode width Ws is preferably thin, and more preferably about 0.01 mm to 10 mm.

  According to experiments, when the intensity of the electric field applied to the recording medium 20 is in the range of 0.1 kV / mm to 10 kV / mm, the electrorheological effect on the processing liquid on the recording medium 20 is large. Therefore, it is preferable to set the interelectrode distance Wp, the electrode width Ws, and the applied voltage so that the intensity of the electric field applied to the recording medium 20 is in the range of 0.1 kV / mm to 10 kV / mm.

[Description of ink set]
Next, an ink set (processing liquid and ink) applied to the inkjet recording apparatus 10 according to the present embodiment will be described in detail.

  The inkjet recording apparatus 10 shown in this example includes a polymerization initiator, a color material diffusion inhibitor, a high-boiling organic solvent, a treatment liquid containing ER effect-expressing particles, a polymerizable compound, and each color ink containing a color material. An ink set composed of the following is used.

  The polymerizable compound refers to a compound having a function of causing a polymerization reaction and curing by an initiating species such as a radical generated from a polymerization initiator described later.

  It is preferably an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is preferably selected from polyfunctional compounds having at least one terminal ethylenically unsaturated bond, more preferably two or more. Such compound groups are widely known in the industrial field, and these can be used without any particular limitation. These include, for example, those having chemical forms such as monomers, prepolymers, that is, dimers, trimers and oligomers, or mixtures thereof and copolymers thereof.

  The polymerizable compound preferably has a polymerizable group such as an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, or an internal double bond group (such as maleic acid) in the molecule, and among them, an acryloyl group or a methacryloyl group. A compound having a group is preferable because it can cause a curing reaction with low energy.

  Only one type of polymerizable compound may be used in one liquid, or two or more types may be used in combination.

  The content of the polymerizable compound contained in the second liquid (here, each color ink of the second liquid) containing the color material (colorant) is preferably in the range of 50 to 99% by mass in the second liquid. The range of 70-99 mass% is more preferable, and the range of 80-99 mass% is still more preferable.

  The polymerization initiator refers to a compound that generates an initiation species such as a radical by the energy of light, heat, or both, and initiates and accelerates the polymerization of the polymerizable compound, and is a known thermal polymerization initiator or bond dissociation energy. A compound having a small bond, a photopolymerization initiator and the like can be selected and used.

  Examples of such radical generator include organic halogenated compounds, carbonyl compounds, organic peroxide compounds, azo polymerization initiators, azide compounds, metallocene compounds, hexaarylbiimidazole compounds, organic boric acid compounds, disulfonic acid compounds, oniums. Examples thereof include salt compounds.

  In the ink set of the present embodiment, a polymerization initiator that cures the polymerizable compound is contained in the first treatment liquid (pretreatment liquid) among a plurality of types of liquids to be used.

  The content of the polymerization initiator is preferably 0.5 to 20% by mass, and 1 to 15% by mass with respect to the total polymerizable compound used in the ink set from the viewpoints of stability over time, curability, and curing rate. More preferred is 3 to 10% by mass.

  A polymerization initiator can be used 1 type or in combination of 2 or more types. Moreover, as long as a required effect is not impaired, it can also be used together with a known sensitizer for the purpose of improving sensitivity.

  The color material (colorant) used in the present embodiment is not particularly limited, and can be appropriately selected from known oil-soluble dyes and pigments as long as the hue and color density suitable for the intended use of the ink can be achieved. Can be used.

  There is no restriction | limiting in particular in the oil-soluble dye which can be used for this invention, Arbitrary things can be used. The content of the dye when using an oil-soluble dye as a colorant (colorant) is preferably in the range of 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, in terms of solid content. 0.2-6 mass% is especially preferable.

  An embodiment in which a pigment is used as the coloring material (coloring agent) is also preferable from the viewpoint that aggregation easily occurs when a plurality of types of liquids are mixed.

  As the pigment used in the present embodiment, either an organic pigment or an inorganic pigment can be used, and as the black pigment, a carbon black pigment or the like is preferably exemplified. In general, pigments of three primary colors of black and cyan, magenta, and yellow are used, but pigments having other hues such as red, green, blue, brown, white, gold, silver, etc. The metallic luster pigment, colorless or light-colored extender pigment, and the like can also be used depending on the purpose.

  In addition, particles having silica, alumina, resin, or the like as a core material and having a dye or pigment fixed on the surface, an insoluble raked product of a dye, a colored emulsion, a colored latex, or the like can also be used as a pigment.

  Furthermore, resin-coated pigments can also be used. This is called a microcapsule pigment, and is also available as a commercial product from Dainippon Ink and Chemicals, Toyo Ink, etc.

  The volume average particle diameter of the pigment particles contained in the liquid in the present embodiment is preferably in the range of 30 to 250 nm, more preferably in the range of 50 to 200 nm, from the viewpoint of the balance between optical density and storage stability. is there. Here, the volume average particle diameter of the pigment particles can be measured by a measuring device such as LB-500 (manufactured by HORIBA).

  In the case of using a pigment as the colorant, the content is from 0.1% by mass in terms of solid content in the second liquid (here, each color ink of the second liquid) from the viewpoint of optical density and jetting stability. The range is preferably 20% by mass, and more preferably 1% by mass to 10% by mass.

  The colorant may be used alone or in combination of two or more. Further, different colorants may be used for each liquid, or the same may be used.

  In the present embodiment, the color material diffusion inhibitor is a second liquid (that is, a second liquid having a colorant ejected onto the first liquid (that is, the first processing liquid) applied to the recording medium (that is, the first liquid). The substance contained in the first liquid for the purpose of preventing the diffusion and bleeding of the second liquid ink).

  The colorant diffusion inhibitor contains at least one selected from the group consisting of a polymer having an amino group, a polymer having an onium group, a polymer having a nitrogen-containing heterocycle, and a metal compound.

  The said polymer etc. may use single type and may use it in combination of multiple types. “Multiple species” refers to, for example, different genus species that belong to polymers having an amino group but have different structures, or a relationship between a polymer having an amino group and a polymer having an onium group. Including some cases. Further, an amino group, an onium group, a nitrogen-containing heterocycle, and a metal compound may be combined in one molecule.

  In the present embodiment, the high boiling point organic solvent (oil) is an organic solvent having a viscosity at 25 ° C. of 100 mPa · s or less or a viscosity at 60 ° C. of 30 mPa · s or less and a boiling point higher than 100 ° C. Indicates.

  The “viscosity” here refers to the viscosity obtained using a RE80 viscometer manufactured by Toki Sangyo Co., Ltd. The RE80 type viscometer is a conical rotor / plate type viscometer corresponding to the E type. Measurement is performed at a rotation speed of 10 rpm using the first rotor. However, for those having a viscosity higher than 60 mPa · s, measurement is performed by changing the number of revolutions to 5 rpm, 2.5 rpm, 1 rpm, 0.5 rpm, or the like as necessary.

  As the usage-amount of the said high boiling point organic solvent, 5-2000 mass% is preferable in conversion of coating amount with respect to the coloring agent to be used, and 10-1000 mass% is more preferable.

  In the ink set of this embodiment, a storage stabilizer can be added for the purpose of suppressing undesired polymerization during storage of a plurality of types of liquids. The storage stabilizer is preferably used in the same liquid as the polymerizable compound, and it is preferable to use a storage stabilizer that is soluble in the liquid or other coexisting components.

  Examples of storage stabilizers include quaternary ammonium salts, hydroxyamines, cyclic amides, nitriles, substituted ureas, heterocyclic compounds, organic acids, hydroquinones, hydroquinone monoethers, organic phosphines, copper compounds, and the like. .

  The addition amount of the storage stabilizer is preferably adjusted as appropriate based on the activity of the polymerization initiator used, the polymerizability of the polymerizable compound, and the type of the storage stabilizer. However, the storage stability and the curability of the ink during liquid mixing are preferred. From the standpoint of balance, the amount is preferably 0.005 to 1% by mass in terms of solid content in the liquid, more preferably 0.01 to 0.5% by mass, and still more preferably 0.01 to 0.2% by mass. .

[Explanation of control system]
FIG. 9 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 100, a system controller 102, an image memory 104, a ROM 106, a media type detection unit 25, a motor driver 116, a heater driver 118, an electric field control unit 120, a light source control unit 122, a print control unit 130, an image. A buffer memory 132, a processing liquid control unit 133, a head driver 134, and the like are provided.

  The communication interface 100 is an interface unit (image input unit) that functions as an image input unit that receives image data sent from the host computer 136. As the communication interface 100, 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.

  Image data sent from the host computer 136 is taken into the inkjet recording apparatus 10 via the communication interface 100 and temporarily stored in the image memory 104. The image memory 104 is a storage unit that temporarily stores an image input via the communication interface 100, and data is read and written through the system controller 102. The image memory 104 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 102 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 102 is a control unit that controls the communication interface 100, the image memory 104, the motor driver 116, the heater driver 118, the electric field control unit 120, the light source control unit 122, the print control unit 130, and the like. In addition to performing communication control with 136, reading / writing control of the image memory 104, and the like, a control signal for controlling the motor 138, the heater 139, and the like of the transport system is generated.

  The ROM 106 stores programs executed by the CPU of the system controller 102 and various data necessary for control. The ROM 106 may be a non-rewritable storage unit or a rewritable storage unit such as an EEPROM. The image memory 104 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.

  As described with reference to FIG. 1, the media type detection unit 25 is a unit that acquires information about the media type, and includes a unit that detects the paper type, wettability, size, and the like of the recording medium 20. Alternatively, instead of or in combination with automatic detection means using a sensor or the like, it is possible to specify information such as paper type and size by inputting from a predetermined user interface.

  Information obtained from the media type detection unit 25 is sent to the system controller 102 of FIG. The system controller 102 calculates the electric field ON / OFF, the electric field application control target value, the UV light irradiation control target value, and the like based on the information obtained from the media type detection unit 25 and the image data for printing. The electric field control unit 120 and the light source control unit 122 are controlled according to the calculation result.

  The motor driver 116 is a driver (drive circuit) that drives the motor 138 in accordance with an instruction from the system controller 102. The heater driver 118 is a driver that drives the heater 139 of the heating drum 37 (see FIG. 1) and other components in accordance with instructions from the system controller 102.

  The electric field control unit 120 in FIG. 9 controls the voltage generated by the DC high voltage generator 78 in accordance with an instruction from the system controller 102 and outputs a control signal for switching ON / OFF of the switches SW11 and SW12 described in FIG. The application / non-application of an electric field by the electrode unit 28 (see FIGS. 1 and 7 to 8) and the electric field strength at the time of application are controlled. That is, in this example, the combination of the electric field control unit 120 and the system controller 102 in FIG. 9 corresponds to the electric field control means.

  The light source control unit 122 in FIG. 9 includes a light source control circuit that controls lighting (ON) / extinguishing (OFF) of the UV light source 16, a lighting position, a light emission amount at the time of lighting, and the like. The light source control unit 122 controls light emission of the UV light source 16 in accordance with a command from the system controller 102.

  The print controller 130 generates various signals for generating an ink ejection control signal and a processing liquid application control signal from image data (multi-valued input image data) in the image memory 104 according to the control of the system controller 102. It functions as signal processing means for performing processing such as processing and correction. In addition, the print control unit 130 functions as an ink discharge control unit that controls the discharge drive of the ink head 50 by supplying the generated ink discharge data to the ink head driver 134 and cooperates with the processing liquid control unit 133. Thus, data for processing liquid application is generated and functions as processing liquid application control means for controlling application driving by the application roller 31.

  The head driver 134 drives the ejection driving actuator 58 of each head 50 based on the ink ejection data given from the print control unit 130. The head driver 134 may include a feedback control system for keeping the head driving conditions constant.

  Necessary signal processing is performed in the print control unit 130, and application of the treatment liquid is controlled via the treatment liquid control unit 133 based on the image data, and from the ink heads 50 of the respective colors via the head driver 134. The ink discharge amount and the discharge timing are controlled. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 130 includes an image buffer memory 132, and image data, parameters, and other data are temporarily stored in the image buffer memory 132 when image data is processed in the print control unit 130. In FIG. 9, the image buffer memory 132 is shown in a mode accompanying the print control unit 130, but it can also be used as the image memory 104. Also possible is an aspect in which the print controller 130 and the system controller 102 are integrated and configured with one processor.

  An overview of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 100 and stored in the image memory 104. At this stage, for example, RGB multi-value input image data is stored in the image memory 104.

  In the ink jet recording apparatus 10, a pseudo continuous tone image is formed by changing the droplet ejection density and dot size of fine dots with ink (coloring material) to the human eye. It is necessary to convert to a dot pattern that reproduces the gradation (shading of the image) as faithfully as possible. Therefore, the original image (RGB) data stored in the image memory 104 is sent to the print control unit 130 via the system controller 102, and ink color is obtained by halftoning processing using a dither method, an error diffusion method, or the like. Converted into dot data (droplet placement data).

  That is, the print control unit 130 performs processing for converting the input RGB image data into dot data of four colors of C, M, Y, and K. Thus, the dot data generated by the print control unit 130 is stored in the image buffer memory 132. The dot data for each color is converted into CMYK droplet ejection data for ejecting ink from the nozzles of the ink head 50, and the ink ejection data to be printed is determined.

  The ink head driver 134 outputs a drive signal for driving the actuator 58 corresponding to each nozzle 51 of the ink head 50 based on the ink ejection data given from the print control unit 130.

  Similarly, the processing liquid control unit 133 drives the application roller 31 based on the processing liquid application data generated from the image data (processing liquid amount data generated in correlation with the ink discharge amount). Drive signal for output.

  As the application roller 31 rotates while being in contact with the recording medium 20, the treatment liquid is applied onto the recording medium 20. In addition, when the drive signal output from the ink head driver 134 is applied to the ink head 50, ink is ejected from the corresponding nozzle 51. An image is formed on the recording medium 20 by controlling the application of the treatment liquid from the application roller 31 and the ink ejection from the ink head 50 in synchronization with the conveyance speed of the recording medium 20.

  As described above, based on the processing liquid application data and the ink discharge data generated through the required signal processing in the print control unit 130, the processing liquid application amount and application timing by the application roller 31 and the ink head 50 are used. Control of the discharge amount and discharge timing of the droplet is performed. Thereby, a desired dot size and dot arrangement are realized.

  According to the inkjet recording apparatus 10 configured as described above, as shown in FIG. 10, the processing liquid 88 is applied onto the recording medium 20 by the application roller 31, and the conductive liquid 88 on the recording medium 20 is electrically conductive. An electric field is applied through the conductive belt 43. By the action of such an electric field, an electroviscous effect is developed in the processing liquid 88 to increase the viscosity of the liquid, the permeation into the recording medium 20 is suppressed, and the processing liquid is held on the recording medium 20 in a liquid state. In this state, the bleeding and spreading of the processing liquid is suppressed, and the movement of the liquid on the recording medium 20 is suppressed.

  By ejecting the ink containing the color material from the ink heads 12M, 12C, 50 onto the processing liquid 88 on the recording medium 20, the ink liquid can be applied where the processing liquid exists sufficiently. Thereby, mixing of different liquids can be caused reliably. Furthermore, due to the presence of the processing liquid 88, the ink droplets coalesce before fixing on the recording medium immediately after the ink has landed on the recording medium, so that the liquid moves and is displaced from the original landing position. In addition to avoiding the phenomenon of “landing interference”, in which the shape of the droplet deforms and the shape of the droplet collapses, resulting in deterioration of image quality, the diffusion of the coloring material in the processing liquid can be suppressed by increasing the viscosity of the processing liquid 88. .

  In this way, the ink can be cured and fixed by irradiating light from the UV light source 16 (see FIG. 1) in a state where the treatment liquid and the ink are reliably mixed. Further, the ease of penetration of the treatment liquid (retention property of the treatment liquid droplets on the recording medium) varies depending on the type of the recording medium (media type). Therefore, in the ink jet recording apparatus 10 of this example, the ON / OFF of the electric field and the strength of the applied voltage (electric field strength) when the electric field is ON are controlled according to the type of the recording medium 20.

  According to the above-described embodiment of the present invention, the penetration of the treatment liquid into the recording medium 20 is suppressed by the electrorheological effect of the treatment liquid, and the ink is adhered in a state where the treatment liquid is sufficiently left on the recording medium. It is possible to mix the two liquids reliably. Thereby, high-quality image formation can be realized.

  Further, according to the present embodiment, by selecting a material in which both the solvent of the processing liquid and the ER effect-expressing particles are colorless and transparent and have a refractive index close to each other, the processing liquid can be prevented from becoming clouded. Can be made colorless and transparent. Thereby, the color of the ink can be faithfully reproduced.

  Furthermore, this embodiment also has the following advantages. That is, if the ultraviolet curable ink contains particles that express an electrorheological effect (ER effect-expressing particles), and the colorant is a pigment, the pigment must be dispersed with respect to the main material. Mixing a large amount of ER effect-expressing particles (dispersed fine particles) in order to strongly develop the electrorheological effect may inhibit pigment dispersion. In addition, when a large amount of ER effect-expressing particles is mixed, there is a problem that the viscosity increases and ink cannot be ejected.

  According to the embodiment of the present invention, by mixing the ER effect dispersed fine particles in the first liquid (processing liquid) having no color material, even when the color material of the ultraviolet effect ink is a pigment, the pigment dispersion is not hindered. The system can be realized. Further, even when a high-viscosity treatment liquid is required in order to develop a high electrorheological effect, it is possible to apply the treatment liquid by means such as coating (means other than ejection by an ink jet method).

  When the average particle size of the ER effect-expressing particles to be dispersed in the treatment liquid is relatively large, for example, in the case of 0.3 μm to 10 μm, the application means is applied as the treatment liquid application means, and the ER to be dispersed in the treatment liquid In the case where the average particle diameter of the effect-expressing particles is relatively small, for example, in the case of 100 nm to 1 μm, an ink jet type liquid discharge means is applied.

  In the overlapping range (average particle size is 0.3 μm to 1 μm), either the application unit or the liquid discharge unit may be applied.

  In place of the structure using the application roller 31 made of a member such as rubber exemplified in FIG. 1, the application roller made of a porous member is used, and the application roller impregnated with the treatment liquid is recorded in contact with the recording medium 20. A processing liquid application mechanism (means) having a structure in which the processing liquid is applied to a predetermined area (all or a part of the recording medium) by moving the medium in the paper feeding direction may be applied. .

  As described above, the means for applying the processing liquid using a member such as an application roller can handle a high-viscosity liquid that is difficult to be discharged by an ink jet type discharge head, and can reduce a large amount of liquid. There is an advantage that it can be adhered in time.

  There is no restriction | limiting in particular as an apparatus used for the said application | coating, A well-known coating apparatus can be suitably selected according to the objective. Examples include air doctor coaters, blade coaters, lot coaters, knife coaters, squeeze coaters, impregnation coaters, reverse roll coaters, transfer roll coaters, gravure coaters, kiss roll coaters, cast coaters, spray coaters, curtain coaters, extrusion coaters, etc. It is done.

In the practice of the present invention, ultraviolet light, visible light, or the like can be used as an exposure light source that imparts energy for advancing polymerization of the polymerizable compound. In addition, energy can be imparted by using radiation other than light, for example, α rays, γ rays, X rays, electron beams, etc. Of these, ultraviolet rays and visible rays are used from the viewpoint of cost and safety. Preferably, ultraviolet rays are used. The amount of energy required for the curing reaction varies depending on the type and content of the polymerization initiator, but is generally about 1 to 500 mJ / cm ² .

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 11 is a configuration diagram of a main part of an ink jet recording apparatus according to the second embodiment of the present invention. In the figure, the same or similar elements as those shown in FIGS. 1 and 10 are denoted by the same reference numerals, and the description thereof is omitted.

  An ink jet recording apparatus 10 ′ shown in FIG. 11 replaces the treatment liquid application mechanism 11 described in FIGS. 1 and 10 as means for applying the first treatment liquid, as shown in FIG. A discharge head (hereinafter referred to as “treatment liquid head”) 11T is provided.

  When the treatment liquid is deposited on the recording medium 20 by ejecting droplets from the treatment liquid head 11T, an electric field is applied to the treatment liquid that has landed on the recording medium 20, and thus an electrorheological effect appears in the treatment liquid. The viscosity of the landing treatment liquid increases. While the electric field is continuously applied, the thickened state by the electrorheological effect is maintained. As a result, the landing treatment liquid is maintained in a substantially hemispherical liquid state on the recording medium 20, and penetration into the recording medium 20, landing interference, penetration penetration, liquid movement, and the like are suppressed.

  In the high viscosity state of the processing liquid, ink is ejected from the ink heads 12M, 12C, 12Y, and 12K onto the processing liquid.

  The treatment liquid head 11T has a length corresponding to the maximum paper width of the recording medium 20 targeted by the ink jet recording apparatus 10 as in the case of the ink heads. This is a full-line head in which a plurality of nozzles (ejection ports) are arranged over a length (full width of the drawable range) exceeding at least one side of the medium 20.

  Although not shown, the structure of the treatment liquid head 11T is substantially the same as that of the ink head 50 described with reference to FIGS. However, since the treatment liquid has only to be deposited substantially uniformly (substantially uniformly) on the area where ink is ejected on the recording medium 20, formation of high-density dots is not required as compared with ink. Therefore, the treatment liquid head 11T can be configured to have a smaller number of nozzles (lower nozzle density) than the ink head 50. Further, a configuration in which the nozzle diameter of the treatment liquid head 11T is larger than the nozzle diameter of the ink head 50 is also possible.

  The processing liquid tank 13 communicates with the processing liquid head 11T via a pipe line 35T, and supplies the processing liquid to the processing liquid head 11T. Although not shown, the processing liquid supply system and the cleaning means (recovery means) for the processing liquid head 11T are substantially the same as the ink supply system and the cleaning means described with reference to FIG.

  FIG. 12 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10 ′ according to the second embodiment shown in FIG. 11. 12, elements that are the same as or similar to those described in FIG. 9 are given the same reference numerals, and descriptions thereof are omitted.

  The print control unit 130 in FIG. 12 generates an ink ejection control signal and a processing liquid ejection control signal from the image data (multi-valued input image data) in the image memory 104 in accordance with the control of the system controller 102. It functions as signal processing means for performing various processing and correction processing for the purpose. In addition, the print control unit 130 functions as an ink discharge control unit that controls the discharge drive of the ink head 50 by supplying the generated ink discharge data to the ink head driver 134 and cooperates with the processing liquid control unit 133. In this way, data for processing liquid discharge is generated and functions as processing liquid application control means for controlling the discharge driving of the processing liquid head 11T.

  The processing liquid control unit 133 uses the processing liquid ejection data (processing liquid dot data generated in correlation with the ink ejection amount) generated from the image data, and each nozzle of the processing liquid head 11T. A drive signal for driving the actuator corresponding to is output. That is, the processing liquid control unit 133 includes means as a head driver for processing liquid.

  When the drive signal output from the processing liquid control unit 133 is applied to the processing liquid head 11T, the processing liquid is discharged from the corresponding nozzle. In addition, when the drive signal output from the ink head driver 134 is applied to the ink head 50, ink is ejected from the corresponding nozzle 51. An image is formed on the recording medium 20 by controlling the processing liquid ejection from the processing liquid head 11T and the ink ejection from the ink head 50 in synchronization with the conveyance speed of the recording medium 20.

  As described above, the ejection amount and ejection timing of the droplets from the processing liquid head 11T and the ink head 50 based on the processing liquid ejection data and the ink ejection data generated through the required signal processing in the print control unit 130. Is controlled. Thereby, a desired dot size and dot arrangement are realized.

  Incidentally, an electrorheological fluid (for example, a dispersion system) to which an electric field is applied from the outside such as the electrode unit 28 has a property that it does not flow unless a stress τ applied from the outside exceeds a certain value τy (yield stress). The value of the yield stress τy is determined by the performance of the electrorheological fluid and the strength of the electric field applied to the electrorheological fluid. That is, by appropriately setting the value of the yield stress τy, the flow of the processing liquid after landing on the recording medium 20 and the penetration into the recording medium can be suppressed, and an effect of improving the printing quality can be obtained.

For example, regarding bleeding and spreading of the processing liquid,
(Capillary force between treatment liquid and media) <(yield stress τy of treatment liquid) ... [Condition 1]
Yield stress τy is set to satisfy the above relationship.

In addition, regarding the interference between the droplets on the media and the movement of the liquid,
(Cohesion force between droplets of treatment liquid) <(yield stress τy of treatment liquid) ... [Condition 2]
Yield stress τy is set to satisfy the relationship.

  Further, by setting the yield stress τy so as to satisfy both of the above [Condition 1] and [Condition 2] and applying the corresponding electric field strength, the treatment liquid is spread and spread, and the droplets are recorded. Interference and liquid movement on the medium 20 can be avoided at the same time.

  According to the ink jet recording apparatus 10 configured as described above, when an electric field is applied to the processing liquid that has landed on the recording medium 20 (electric field ON), an electrorheological effect is developed and the viscosity of the liquid is increased. Infiltration into the liquid is suppressed, and the droplet shape is maintained. In this state, bleeding and spreading of the processing liquid are suppressed, and interference between adjacent droplets on the recording medium 20 and liquid movement are suppressed.

  In this state, by ejecting ink containing a color material from the ink head 50, the ink liquid can be applied to a place where the processing liquid is sufficiently present. Thereby, mixing of different liquids can be caused reliably.

  The ink can be cured and fixed by irradiating light from the UV light source 16 (see FIG. 1) in a state where the treatment liquid and the ink are reliably mixed. Further, the ease of penetration of the treatment liquid (retention property of the treatment liquid droplets on the recording medium) varies depending on the type of the recording medium (media type). Therefore, in the ink jet recording apparatus 10 of this example, the ON / OFF of the electric field and the strength of the applied voltage (electric field strength) when the electric field is ON are controlled according to the type of the recording medium 20.

  As shown in FIG. 11, in the case of a configuration in which the processing liquid is attached using an ink jet type liquid discharge head (processing liquid head 11T), a required range on the recording medium (for example, ink) is used based on the image data. Since the treatment liquid can be selectively attached (limited to the drawing portion), there is an advantage that the wasteful consumption of the treatment liquid can be reduced as compared with the application means using a roller or the like.

[Modification 1]
In each of the above embodiments, the example of mixing two liquids of the pretreatment liquid and the ink has been described. However, the present invention can also be applied to a case where three or more kinds of liquids are mixed.

  It is also possible to prepare two or more types of pretreatment liquids and select one or two or more suitable treatment liquids according to the type of recording medium.

[Modification 2]
Instead of the transport unit 26 described with reference to FIGS. 1 and 7 to 8, a configuration using an endless belt in which an electrode pair for generating an electric field is embedded is also possible. In this case, for example, the cross-sectional structure of the belt can be the same as that shown in FIG. Further, for the transport unit 26, instead of the belt transport mechanism, a structure (table transport mechanism) for transporting a table for holding media can be used.

[Modification 3]
The ink jet recording apparatus 10 ′ described with reference to FIG. 11 has a configuration in which the treatment liquid head 11T is disposed only on the upstream side (right side in FIG. 11) of the ink head 12C in the recording medium conveyance direction. In addition, a configuration in which the processing liquid head is disposed on the upstream side of each of the ink heads 12M, 12C, 12Y, and 12K is also possible. With this configuration, it is possible to apply an appropriate amount of processing liquid for each ink color.

[Modification 4]
In the above description, an example in which an ultraviolet curable ink is used has been described. However, the present invention is not limited to a photocurable ink typified by an ultraviolet curable ink but is cured by an electron beam, an X-ray, or the like. Other radiation curable inks can be used, and a fixing accelerating processing unit using a radiation source suitable for activating the curing agent (activating the polymerization) according to the ink used ( Radiation irradiating means) is provided.

  In each of the above embodiments, an ink jet recording apparatus using a page-wide full-line head having a nozzle array with a length corresponding to the entire width of the medium (recording medium) has been described. However, the present invention is also applicable to an inkjet recording apparatus that uses a shuttle head that records an image while reciprocating a short recording head.

1 is an overall configuration diagram of an ink jet recording apparatus according to a first embodiment of the present invention. Plane perspective view showing a structural example of an ink head Plane perspective view showing another configuration example of a full-line head Sectional drawing which shows the three-dimensional structure of the droplet discharge element (ink chamber unit corresponding to 1 nozzle) for 1 channel FIG. 2 is an enlarged view showing the nozzle arrangement of the ink head shown in FIG. Schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus of this example Plane schematic diagram showing an example of the electrode arrangement structure of the electrode unit Sectional drawing which follows the 8-8 line in FIG. 1 is a principal block diagram showing a system configuration of an ink jet recording apparatus according to a first embodiment. 1 is a configuration diagram of a main part of an ink jet recording apparatus according to a first embodiment. FIG. 3 is a main part configuration diagram of an ink jet recording apparatus according to a second embodiment of the present invention. A principal block diagram showing a system configuration of an ink jet recording apparatus according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10 '... Inkjet recording device, 11 ... Processing liquid application mechanism, 11T ... Processing liquid head, 12M, 12C, 12Y, 12K ... Ink head, 13 ... Processing liquid tank, 16 ... UV light source, 20 ... Recording medium DESCRIPTION OF SYMBOLS 22 ... Media supply part 25 ... Media type detection part 26 ... Conveyance part 28 ... Electrode unit 31 ... Application roller 43 ... Slightly conductive belt 50 ... Ink head 51 ... Nozzle 52 ... Pressure chamber 58 ... Actuator, 78 ... DC high voltage generator, 102 ... System controller, 120 ... Electric field controller, 122 ... Light source controller, 133 ... Treatment liquid controller

Claims (7)

A treatment liquid application means for applying a treatment liquid containing a polymerization initiator, particles expressing an electrorheological effect, and a solvent to a recording medium;
An electric field applying means for applying an electric field to the treatment liquid adhered on the recording medium;
An ink ejection means for ejecting ink containing a coloring material and a radiation curable polymerizable compound on the recording medium to which the treatment liquid is attached;
Radiation irradiating means for irradiating radiation for curing the ink on the recording medium;
With
The image forming apparatus, wherein the solvent and the particles exhibiting the electrorheological effect in the treatment liquid are both colorless and transparent and are made of materials having refractive indexes that are close to each other.   The image forming apparatus according to claim 1, wherein the processing liquid contains a color material diffusion preventing agent that prevents the color material from diffusing. The average particle diameter of the particles expressing the electrorheological effect in the treatment liquid is 0.3 μm to 10 μm,
The image forming apparatus according to claim 1, wherein the processing liquid application unit is a coating unit that applies the processing liquid while being in contact with the recording medium. The average particle diameter of the particles expressing the electrorheological effect in the treatment liquid is 100 nm to 1 μm,
The image forming apparatus according to claim 1, wherein the processing liquid applying unit is a discharge unit that discharges the processing liquid as droplets by an ink jet method. A treatment liquid tank for storing a treatment liquid to be supplied to the treatment liquid application unit;
The image forming apparatus according to claim 1, further comprising: a stirring unit that stirs the processing liquid in the processing liquid tank. A process for applying to a recording medium a treatment liquid comprising a polymerization initiator, particles exhibiting an electrorheological effect, and a solvent, both of which are colorless and transparent, and which are made of materials having refractive indexes close to each other. A liquid application step;
An electric field applying step for applying an electric field to the treatment liquid adhered on the recording medium;
An ink ejection step for ejecting ink containing a coloring material and a radiation curable polymerizable compound on the recording medium to which the treatment liquid is attached;
A radiation irradiation step of irradiating with radiation for curing the ink on the recording medium;
An image forming method comprising: A treatment liquid comprising a polymerization initiator, particles exhibiting an electrorheological effect, and a solvent, wherein both the solvent and the particles are colorless and transparent, and are composed of materials having refractive indexes close to each other;
An ink containing a coloring material and a radiation-curable polymerizable compound;
An ink set comprising:

Images