JP2011168021A - Inkjet recording apparatus and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform a curing-fixation by suppressing unevenness in curing and fixed wrinkles even when a water-based ultraviolet curing type ink is used, and at the same time, to increase the thermal efficiency by reusing hot air, which has been generated at the time of the curing-fixation, for drying. <P>SOLUTION: A recording medium onto the recording surface of which the water-based ultraviolet curing type ink has been discharged is dried by jetting hot air while carrying the recording medium by suction-restraining by a drying unit. A fixing unit is constituted by arranging an ultraviolet irradiation means in a transfer cylinder-carrying means which carries the recording medium under a state that the distal end of the recording medium is held and the recording surface side is bent into a recess shape. The upper sections of the fixing unit and the drying unit are covered by a cover member. Then, air which has been heated by the heat generated by the ultraviolet irradiation means is fed by a fan into a space between the cover member and the drying unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly, to a recording medium conveyed through a large number of drums, printing is performed with aqueous ultraviolet curable ink from an ink jet head, and the recording medium after printing is used. The present invention relates to an ink jet recording apparatus and an ink jet recording method for drying and fixing.

  Conventionally, in an inkjet recording method using water-based ultraviolet curable ink, ink moisture soaks into a recording medium such as paper, and the recording medium absorbs the ink moisture, whereby the recording medium expands and deforms, and wrinkles called cockle are generated, Even after drying, wrinkles and curls remain, causing deterioration in image quality. In addition, if moisture is present in the ink during ultraviolet irradiation, there is a problem that ink curing does not proceed efficiently and high-speed fixing cannot be realized.

  On the other hand, for example, after applying thermal energy to the recording medium held on the outer peripheral surface of the drum by electrostatic adsorption or suction by a holding mechanism, at least a part of the recording medium is released, and the recording medium is pressed by the pressure roller. An ink jet recording apparatus is known in which a recording medium is held again by a holding mechanism, an ultraviolet curable ink is ejected from a recording head, an ultraviolet ray is irradiated to the recording head, and the image is cured and fixed to record an image. (For example, refer to Patent Document 1).

  For example, in an image forming method using water-based ultraviolet curable ink, in order to realize high-speed fixing on a recording medium, hot air is blown on the image by means of hot air blowing to the image to evaporate water and volatile components. Thereafter, an image is cured and fixed by irradiating the ultraviolet ray with the maximum intensity by an ultraviolet ray irradiating means (see, for example, Patent Document 2).

JP 2007-144773 A JP 2007-245653 A

  However, if the ink is dried and then cured with ultraviolet rays while the recording medium is sucked and held on the conveying means, it is caused by uneven curing due to drying due to the suction holes and ink curing shrinkage at the time of fixing between the restraining portion and the non-restraining portion. There is a problem that fixing flaws occur.

  The present invention has been made in view of such circumstances, and even when aqueous ultraviolet curable ink is used, curing unevenness and fixing wrinkles are suppressed and curing and fixing are performed efficiently, and hot air generated during curing and fixing is reduced. An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method that can improve thermal efficiency by being reused for drying.

  In order to achieve the above object, the invention according to claim 1 is characterized in that the aqueous ultraviolet curable type comprises a liquid ejection head that ejects aqueous ultraviolet curable ink onto a recording surface of a recording medium and a holding means formed on an outer peripheral surface. The recording medium is held by holding the front end of the recording medium on which the ink is ejected on the recording surface, and adsorbing the back surface side of the recording surface to the outer peripheral surface through a suction hole formed in the outer peripheral surface. A restraint drying unit having a suction restraint cylinder that restrains and conveys, and a hot air drying unit that is disposed to face an outer peripheral surface of the suction restraint cylinder and that blows hot air on the recording medium, and is disposed on the downstream side of the restraint drying unit. A transfer cylinder conveying means for conveying the recording medium in a state where the leading end of the recording medium is held and the recording surface side is curved in a concave shape, and disposed inside the transfer cylinder conveying means, Providing an ink jet recording apparatus characterized by comprising: a fixing unit having an ultraviolet irradiation means for irradiating ultraviolet rays to the recording surface of the recording medium conveyed by the transfer cylinder conveying means.

  Thereby, even when aqueous ultraviolet curable ink is used, curing unevenness and fixing flaws can be suppressed and curing and fixing can be performed efficiently.

  According to a second aspect of the present invention, a plurality of the ultraviolet irradiation means are arranged along the curved shape of the recording medium conveyed by the transfer cylinder conveying means.

  As a result, it is possible to reduce the irradiation intensity of each ultraviolet irradiation means and to obtain curing conditions in the ultraviolet irradiation time, to reduce the heat generation amount of the ultraviolet irradiation means, and to reduce the cost. .

  According to a third aspect of the present invention, there is provided a cover member that covers the upper portion of the fixing unit and the drying unit, and air heated by heat generated by the ultraviolet irradiation means in a space between the cover member and the drying unit. A first fan for blowing air is provided.

  Accordingly, it is possible to improve the thermal efficiency by reusing the hot air generated at the time of curing and fixing for drying.

  According to a fourth aspect of the present invention, the cover member includes a heat insulating member.

  Thereby, the heat generated in the fixing unit can be sent to the drying unit and reused without escaping.

  According to a fifth aspect of the present invention, the transfer drum transporting unit includes a guide member for transporting the recording medium in a state where the recording surface side is curved in a concave shape.

  As a result, the transfer drum transport means can reliably transport the recording medium in a state where the recording surface is curved in a concave shape.

  According to a sixth aspect of the present invention, the guide member includes a heat insulating member.

  As a result, the heat generated in the fixing unit can be utilized without escaping.

  Further, according to a seventh aspect of the present invention, the ultraviolet irradiation means directs the air heated by the heat generated by the ultraviolet irradiation means toward the recording medium conveyed by the transfer cylinder conveying means or the drying. A second fan that blows air toward the unit side is provided.

  Thereby, the heat generated in the fixing unit can be used efficiently.

  An exhaust fan for exhausting air in a space formed between the cover member and the drying unit is installed on the most upstream side of the cover member in the recording medium conveyance direction. It is characterized by that.

  As a result, it is possible to improve the drying efficiency by exhausting the air in the cover that is used for drying and contains moisture.

  According to a ninth aspect of the present invention, the inner surface of the cover member is covered with a member that absorbs moisture.

  Thereby, drying efficiency can be improved.

  Similarly, in order to achieve the above object, the invention according to claim 10 is formed on the outer peripheral surface of the suction restraining cylinder and the ink discharging step of discharging the aqueous ultraviolet curable ink onto the recording surface of the recording medium. The holding means holds the tip of the recording medium on which the water-based ultraviolet curable ink is discharged onto the recording surface, and the back side of the recording surface is made to the outer peripheral surface through a suction hole formed in the outer peripheral surface. A constrained drying process in which hot air is applied to the recording surface of the recording medium while drying and conveying the recording medium, and the recording medium dried in the constrained drying process is held by the transfer cylinder conveying means. A fixing step in which the recording surface of the recording medium is fixed by irradiating the recording surface with ultraviolet rays by means of ultraviolet irradiation means disposed inside the transfer drum conveying means while conveying the recording surface in a concavely curved state. When Further comprising a providing an ink jet recording method comprising.

  Thereby, even when aqueous ultraviolet curable ink is used, curing unevenness and fixing flaws can be suppressed and curing and fixing can be performed efficiently.

  Further, as shown in claim 11, the upper part of the transfer cylinder transporting means and the suction restraining cylinder is covered with a cover member, and the ultraviolet irradiation means generates in a space formed between the cover member and the suction restraining cylinder. It is characterized by blowing air heated by the generated heat.

  Accordingly, it is possible to improve the thermal efficiency by reusing the hot air generated at the time of curing and fixing for drying.

  As described above, according to the present invention, even when an aqueous ultraviolet curable ink is used, curing unevenness and fixing flaws can be suppressed and curing fixing can be performed efficiently. In addition, when the fixing unit and drying unit are covered with a cover and the heat generated by the fixing unit is sent to the drying unit by a fan, heat efficiency is improved by reusing the hot air generated during curing and fixing for drying. Can be achieved.

1 is a schematic configuration diagram illustrating an embodiment of an inkjet recording apparatus according to the present invention. It is a principal block diagram showing the system configuration of the ink jet recording apparatus. It is a block diagram which shows the principal part of the inkjet recording device of this embodiment. It is a block diagram which expands and shows the mode of the fixing | fixed part and drying part in other embodiment, (a) shows the mechanism for aiming at the thermal efficiency improvement of a fixing part and a drying part, (b) is an ultraviolet light source. The structure is shown. FIG. 6 is an enlarged configuration diagram illustrating a state of a fixing unit and a drying unit according to another embodiment, wherein (a) illustrates a mechanism for improving thermal efficiency of the fixing unit and the drying unit, and (b) illustrates an ultraviolet light source. The structure of is shown.

  Hereinafter, an ink jet recording apparatus and an ink jet recording method according to the present invention will be described in detail with reference to the accompanying drawings.

  Usually, in an ink jet recording apparatus using water-based ultraviolet curable ink, the recording medium on which the ink has been discharged is dried while being sucked and transported to the drying drum of the drying unit, and then the fixing drum of the fixing unit via the transfer cylinder transporting means. When the recording medium carried on the outer peripheral surface of the fixing drum is irradiated with ultraviolet rays and cured and fixed, the present invention eliminates the fixing drum and provides an ultraviolet light source inside the transfer cylinder conveying means. It is arranged so that the transfer drum transport means is a fixing unit, and is cured and fixed by the transfer drum transport means. Furthermore, the heat of the ultraviolet light source arranged in the transfer drum transport means is sent to the drying unit, and this heat is reused for drying the recording medium, thereby improving the thermal efficiency.

  FIG. 1 is a schematic configuration diagram showing an embodiment of an ink jet recording apparatus according to the present invention.

  In the inkjet recording apparatus 100, water-based ultraviolet curable inks of a plurality of colors are applied from the inkjet heads 172M, 172K, 172C, and 172Y to the recording surface of the recording medium 124 held by the impression cylinder (drawing drum 170) of the drawing unit 116. It is an impression cylinder direct drawing type ink jet recording apparatus that forms a desired color image by dropping, and a treatment liquid (including an aggregating agent for aggregating components in the ink composition) on the recording medium 124 before ink ejection. And an on-demand type image forming apparatus to which a two-liquid reaction (aggregation) method for forming an image on a recording medium 124 by reacting a treatment liquid and an ink liquid is applied.

  That is, as shown in FIG. 1, the inkjet recording apparatus 100 mainly includes a paper feeding unit 112, a treatment liquid application unit 114, a drawing unit 116, a drying unit 118 (drying unit), a fixing unit 120 (fixing unit), and a discharge unit. A paper portion 122 is provided.

  The paper feeding unit 112 is a mechanism that supplies the recording medium 124 to the processing liquid application unit 114, and the recording medium 124 that is a sheet is stacked on the paper feeding unit 112. The paper feed unit 112 is provided with a paper feed tray 150, and the recording medium 124 is fed from the paper feed tray 150 to the processing liquid application unit 114 one by one. In order to prevent the recording medium 124 from being lifted, the paper feed tray 150 may be provided with a suction hole on the outer surface, and a suction unit that performs suction from the suction hole may be connected.

  In the inkjet recording apparatus 100 of the present embodiment, a plurality of types of recording media 124 having different paper types and sizes (paper sizes) can be used as the recording medium 124. A mode is also possible in which a plurality of paper trays (not shown) are provided in the paper feed unit 112 to distinguish and collect various recording media and the paper to be fed to the paper feed tray 150 is automatically switched from among the plurality of paper trays. In addition, a mode is also possible in which the operator selects or replaces the paper tray as necessary. In this example, a sheet (cut paper) is used as the recording medium 124, but a configuration in which continuous paper (roll paper) is cut to a required size and fed is also possible.

  The processing liquid application unit 114 is a mechanism that applies the processing liquid to the recording surface of the recording medium 124. The treatment liquid includes an aggregating agent that agglomerates the components in the ink composition applied by the drawing unit 116, and causes an aggregation reaction with the ink when the treatment liquid comes into contact with the ink. Separation is promoted, and it is possible to form a high-quality image without causing blurring after ink landing, landing interference (unification), or color mixing. In addition, as a process liquid, it can also comprise using another component other than a coagulant | flocculant as needed. By using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image with excellent density and resolution can be obtained even with high speed recording (for example, reproducibility of fine lines and fine portions).

  As shown in FIG. 1, the treatment liquid application unit 114 includes a paper feed drum 152, a treatment liquid drum 154, and a treatment liquid application device 156. The treatment liquid drum 154 is a drum that holds and rotates the recording medium 124. The processing liquid drum 154 includes a claw-shaped holding means (gripper) 155 on the outer peripheral surface thereof, and the recording medium 124 is sandwiched between the claw of the holding means 155 and the peripheral surface of the processing liquid drum 154. The tip can be held. The treatment liquid drum 154 may be provided with a suction hole on the outer peripheral surface thereof and connected to a suction unit that performs suction from the suction hole. As a result, the recording medium 124 can be held in close contact with the peripheral surface of the treatment liquid drum 154.

  A processing liquid coating device 156 is provided outside the processing liquid drum 154 so as to face the peripheral surface thereof. In the recording medium 124, the processing liquid is applied to the recording surface by the processing liquid application device 156.

  The recording medium 124 to which the processing liquid is applied by the processing liquid applying unit 114 is transferred from the processing liquid drum 154 to the drawing drum 170 of the drawing unit 116 via the intermediate transfer unit 126 (first transfer cylinder transfer unit).

  The drawing unit 116 includes a drawing drum 170 and inkjet heads 172M, 172K, 172C, and 172Y. Although not shown in FIG. 1, a sheet suppression roller for removing the wrinkles of the recording medium 124 is disposed on the front side of the ink jet heads 172M, 172K, 172C, and 172Y with respect to the drawing drum 170. Also good.

  Similar to the treatment liquid drum 154, the drawing drum 170 includes a claw-shaped holding means (gripper) 171 on its outer peripheral surface, and holds and fixes the leading end of the recording medium. The drawing drum 170 has a plurality of suction holes on the outer peripheral surface, and the recording medium 124 is attracted to the outer peripheral surface of the drawing drum 170 by negative pressure. As a result, contact with the head due to paper floating is avoided, and paper jam is prevented. In addition, image unevenness due to fluctuations in the clearance with the head is prevented.

  The recording medium 124 thus fixed to the drawing drum 170 is conveyed with the recording surface facing outward, and water-based ultraviolet curable ink is ejected from the inkjet heads 172M, 172K, 172C, 172Y onto this recording surface. Is done.

  The inkjet heads 172M, 172K, 172C, and 172Y are full-line inkjet recording heads (inkjet heads) each having a length corresponding to the maximum width of the image forming area on the recording medium 124. Is formed with a nozzle row in which a plurality of nozzles for ink ejection are arranged over the entire width of the image forming area. Each inkjet head 172M, 172K, 172C, 172Y is installed so as to extend in a direction orthogonal to the conveyance direction of the recording medium 124 (the rotation direction of the drawing drum 170).

  The droplets of the corresponding color ink are ejected from the inkjet heads 172M, 172K, 172C, and 172Y toward the recording surface of the recording medium 124 held in close contact with the drawing drum 170, whereby the processing liquid application unit 114 The ink comes into contact with the treatment liquid previously applied to the recording surface, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. As a result, the color material flow on the recording medium 124 is prevented, and an image is formed on the recording surface of the recording medium 124.

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

  The drawing unit 116 configured as described above can perform drawing on the recording medium 124 in a single pass. Thereby, high-speed recording and high-speed output are possible, and productivity can be improved.

  The recording medium 124 on which an image is formed by the drawing unit 116 is transferred from the drawing drum 170 to the drying drum 176 of the drying unit 118 via the intermediate conveyance unit 128 (second transfer cylinder conveyance unit).

  The drying unit 118 is a mechanism that dries moisture contained in the solvent separated by the color material aggregating action, and includes a drying drum 176 and a solvent drying device 178 as shown in FIG.

  Similar to the processing liquid drum 154, the drying drum 176 includes a claw-shaped holding unit (gripper) 177 on the outer peripheral surface thereof, holds the tip of the recording medium 124 by the holding unit 177, and sucks holes on the outer peripheral surface of the drum. The recording medium 124 can be adsorbed to the drying drum 176 by a negative pressure. Further, a blowing unit 180 and a solvent drying device 178 are provided so as to face the outer peripheral surface of the drying drum 176.

  The blowing unit 180 is for assisting the adsorption of the recording medium 124 to the drying drum 176, and blows air obliquely toward the end of the recording medium 124 in the width direction, and the front end thereof is held by the holding unit 177. The recording medium 124 holding the toner is smoothed and reliably adsorbed from the front end side toward the rear end side without generating wrinkles.

  The solvent drying device 178 is arranged at a position facing the outer peripheral surface of the drying drum 176, and includes hot air drying means 182 in which a plurality of combinations of IR heaters and fans are arranged. Various drying conditions can be realized by appropriately adjusting the temperature and air volume of the hot air blown toward the recording medium 124 from each hot air jet nozzle (not shown) of the hot air drying means 182. The recording medium 124 is conveyed while being restrained by suction on the outer peripheral surface of the drying drum 176 so that the recording surface faces outward, and the recording surface is dried by the IR heater, the hot air jet nozzle, and the like.

  Further, the drying drum 176 has suction holes on the outer peripheral surface thereof, and has suction means for performing suction from the suction holes. As a result, the recording medium 124 can be held in close contact with the peripheral surface of the drying drum 176. Further, by performing negative pressure suction, the recording medium 124 can be restrained by the drying drum 176, so that the recording medium 124 can be prevented from being clogged.

  The recording medium 124 that has been dried by the drying unit 118 is transferred from the drying drum 176 to the intermediate conveyance unit 130 (third transfer cylinder conveyance unit). The third transfer cylinder conveying unit 130 includes an ultraviolet light source 190 inside, and constitutes a fixing unit 120 that irradiates ultraviolet rays while conveying the recording medium 124 to cure and fix the ink. Further, in order to send the heat of the ultraviolet light source 190 to the drying unit 118 and reuse it, a cover and a fan are provided to cover the third transfer drum transport unit 130 and the drying unit 118, which will be described in detail later. To do.

  A paper discharge unit 122 is provided following the fixing unit 120 configured by the third transfer drum transport unit 130 in which the ultraviolet light source 190 is disposed. A paper discharge unit 192 is installed in the paper discharge unit 122. Between the third transfer cylinder conveying means 130 as the fixing unit 120 and the paper discharge unit 192, transfer cylinders 194 and 195 and a conveyance chain 196 are provided. The transport chain 196 is wound around stretching rollers 197 and 198. The recording medium 124 that has passed through the third transfer cylinder transfer means 130 is sent to the transfer chain 196 via the transfer cylinder 194 and transferred from the transfer chain 196 to the paper discharge unit 192.

  Although not shown in FIG. 1, the ink jet recording apparatus 100 of the present example has an ink storage / loading unit that supplies ink to each of the ink jet heads 172M, 172K, 172C, and 172Y, and a treatment liquid application, in addition to the above configuration. A head maintenance unit for supplying a processing liquid to the unit 114 and cleaning the ink jet heads 172M, 172K, 172C, 172Y (wiping, purging, nozzle suction, etc. of the nozzle surface) A position detection sensor for detecting the position of the recording medium 124, a temperature sensor for detecting the temperature of each part of the apparatus, and the like are provided.

  FIG. 2 is a principal block diagram showing the system configuration of the inkjet recording apparatus 100.

  The inkjet recording apparatus 100 includes a communication interface 80, a system controller (system controller) 82, an image memory 84, a motor driver 86, a heater driver 88, a print controller 90, a maintenance controller 92, a head driver 94, and the like.

  The communication interface 80 is an interface unit that receives image data sent from the host computer 96. As the communication interface 80, 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 for speeding up communication may be mounted. The image data sent from the host computer 96 is taken into the ink jet recording apparatus 100 via the communication interface 80 and temporarily stored in the image memory 84.

  The image memory 84 is a storage unit that temporarily stores an image input via the communication interface 80, and data is read and written through the system control unit 82. The image memory 84 is not limited to a memory composed of semiconductor elements, and a magnetic medium such as a hard disk may be used.

  The system control unit 82 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 100 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. To do. That is, the system control unit 82 controls the communication interface 80, the image memory 84, the motor driver 86, the heater driver 88, and the like, and generates control signals for controlling the heater 99 and the host computer 96.

  The image memory 84 stores programs executed by the CPU of the system control unit 82 and various data necessary for control. Note that the image memory 84 may be a non-rewritable storage means or a rewritable storage means such as an EEPROM. The image memory 84 may be used as a temporary storage area for image data, and may be used as a program development area and a calculation work area for the CPU.

  The system control unit 82 is connected to an EEPROM 85 that stores various control programs and an image processing unit 87 that performs various image processes on image data. In response to a command from the system control unit 82, a control program is read from the EEPROM 85 and executed. Note that the EEPROM 85 may also be used as a storage unit for operating parameters and the like.

  The motor driver 86 is a driver that drives the motor 98 in accordance with an instruction from the system control unit 82. In FIG. 2, the motor (actuator) disposed in each part of the inkjet recording apparatus 100 is represented by reference numeral 98. For example, the motor 98 in FIG. 2 includes motors that drive the intermediate transport units 126, 128, and 130, the paper feed drum 152, the processing liquid drum 154, the drawing drum 170, and the drying drum 176 in FIG.

  The heater driver 88 is a driver that drives the heater 99 in accordance with an instruction from the system control unit 82. In FIG. 2, a plurality of heaters provided in the ink jet recording apparatus 100 are represented by reference numeral 99. For example, the heater 99 shown in FIG. 2 includes the heater of the treatment liquid application unit 114 and the IR heater of the drying unit 118 shown in FIG.

  In addition, a maintenance control unit 92 is connected to the system control unit 82. The maintenance control unit 92 controls a maintenance drive unit 93 that drives a maintenance unit (not shown) including a cap and a cleaning blade in accordance with an instruction from the system control unit 82.

  The print control unit 90 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the image memory 84 under the control of the system control unit 82. The controller is a controller that controls the treatment liquid application driver 95 to apply the treatment liquid from the treatment liquid application device 156 to the recording medium 124 and supplies the generated print data (dot data) to the head driver 94. . Necessary signal processing is performed in the print controller 90, and the ejection droplet amount (droplet ejection amount) and ejection timing of the inkjet heads 172M, 172K, 172C, 172Y are controlled via the head driver 94 based on the image data. Is done. Thereby, a desired dot size and dot arrangement are realized.

  Further, a UV irradiation means driver 97 for controlling the ultraviolet light source 190 is connected to the system control unit 82.

  FIG. 3 shows an enlarged view of the processing liquid application unit 114, the drawing unit 116, the drying unit 118, and the fixing unit 120 (third transfer cylinder conveying unit 130), which are the main parts of the ink jet recording apparatus 100 of the present embodiment. The ink jet recording apparatus according to the invention will be described in more detail.

  As shown in FIG. 3, the processing liquid drum 154, the intermediate transport unit 126 (first transfer drum transport unit), the drawing drum 170, the intermediate transport unit 128 (second transfer drum transport unit), the drying drum 176, and the intermediate transport unit 130 (third transfer cylinder transport means) are arranged side by side, and the recording medium 124 is transported by these, and while being transported, treatment liquid application, drawing, drying, and fixing (curing) are sequentially performed. Yes.

  Each intermediate conveyance section (the first transfer drum transfer means 126, the second transfer drum transfer means 128, and the third transfer drum transfer means 130) includes guide members 127, 129, and 131 with ribs, respectively, and sandwiches the rotation shaft. A holding claw (not shown) at the tip of the arm extending in the direction facing 180 degrees grips the tip of the recording medium 124 and rotates around the rotation axis, and the rear end of the recording medium 124 is free. The recording medium 124 is conveyed along the guide members (127, 129, 131) so that the back side of the recording surface is convex.

  The intermediate transport units 126, 128, and 130 may be configured to use a chain gripper to grip the recording medium 124 and transport it with the back side convex.

  The ink jet recording apparatus 100 according to the present embodiment records an image on a recording surface of a recording medium 124. The recording medium 124 is not particularly limited, but is a so-called high-quality paper used for general offset printing. Ordinary printing paper mainly composed of cellulose, such as coated paper or art paper, can be used. General printing paper mainly composed of cellulose is relatively slow in ink absorption and drying in image recording by a general ink jet method using water-based ink, and color material movement is likely to occur after droplet ejection, and image quality is likely to deteriorate. However, the inkjet recording apparatus 100 of the present embodiment can perform high-quality image recording excellent in color density and hue by suppressing color material movement.

  Of the recording media, so-called coated paper used for general offset printing is preferred. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. The coated paper is liable to cause quality problems such as glossiness and scratch resistance of the image in normal aqueous inkjet image formation. However, in the inkjet recording apparatus 100 of the present embodiment, gloss unevenness is suppressed and glossiness is reduced. An image having good abrasion resistance can be obtained. In particular, a coated paper having a base paper and a coat layer containing an inorganic pigment is preferably used, and a coated paper having a base paper and a coat layer containing kaolin and / or calcium bicarbonate is more preferably used. Specifically, art paper, coated paper, lightweight coated paper, or finely coated paper is more preferable.

  As described above, the processing liquid application unit 114 applies the processing liquid to the recording surface of the recording medium 124.

  The film thickness of the processing liquid applied to the recording surface by the processing liquid coating apparatus 156 is sufficiently smaller than the droplet diameter of the ink ejected from the inkjet heads 172M, 172K, 172C, 172Y of the drawing unit 116. Is desirable. For example, when the ink droplet ejection amount is 2 pl (picoliter), the average diameter of the droplets is 15.6 μm. At this time, when the film thickness of the processing liquid is large, the ink dots float in the processing liquid without contacting the surface of the recording medium 124. Therefore, in order to obtain a landing dot diameter of 30 μm or more when the ink droplet ejection amount is 2 pl, it is desirable that the film thickness of the treatment liquid is 3 μm or less.

Although not shown in the figure, the processing liquid coating device 156 is mainly composed of a processing liquid container, a metering roller, and a coating roller. A processing liquid is stored in the processing liquid container, and a part of the measuring roller is immersed in the processing liquid. As the metering roller, a metal roller and an anilox roller in which a large number of cells are regularly formed with a certain number of lines on a roller peripheral surface having a ceramic coating on the surface of the metal roller are preferably used. As the material of the metal roller, iron, SUS, or the like is used. When iron is used as the material, the surface may be plated with chromium or the like in order to improve surface hydrophilicity, wear resistance, and rust resistance. As the cell structure of the anilox roller, for example, those having 150 to 400 lines, a cell depth of 20 to 75 μm, and a cell capacity of 30 cm ³ / m ^{2 to} 60 cm ³ / m ² can be suitably used. . The diameter of the measuring roller is, for example, 20 mm or more and 100 mm or less.

  The metering roller is rotatably supported and connected to a motor (not shown), and is driven to rotate at a constant speed. Therefore, the processing liquid in the processing liquid container can be attached to the surface of the measuring roller, and this processing liquid can be transferred to the surface of the coating roller. The rotation direction of the metering roller may be the same as that of the application roller, and the peripheral speed of the outer periphery of the roller may be the same as that of the application roller, or a speed difference may be provided. When providing a speed difference, the peripheral speed of the metering roller is preferably 80% or more and 140% or less with respect to the peripheral speed of the application roller. By adjusting the peripheral speed between the application roller and the metering roller, the transfer rate from the metering roller to the application roller can be adjusted, and the coating film thickness on the recording medium 124 can be adjusted.

  A metering doctor blade is provided on the surface of the metering roller so as to come into contact therewith. The doctor blade is arranged on the upstream side in the rotation direction of the measuring roller with respect to the contact position between the measuring roller and the applying roller, and can measure the application liquid by scraping off the application liquid on the surface of the measuring roller. Thereby, the coating liquid measured by the doctor blade can be supplied to the coating roller.

  As the coating roller, a rubber roller having a rubber layer such as EPDM or silicon on the surface is preferably used. The application roller is rotatably supported and connected to a motor (not shown) and is driven to rotate at a constant speed. The rotation direction of the application roller is the same as that of the processing liquid drum 154, and the peripheral speed of the roller outer periphery is also rotated at the same speed as that of the processing liquid drum 154. As a result, the processing liquid transferred from the metering roller to the application roller is applied to the recording medium 124 held on the processing liquid drum 154.

  As described above, since the processing liquid coating apparatus 156 applies the processing liquid with the roller, the processing liquid can be uniformly applied to the recording medium 124 with a small coating amount. Further, the processing liquid coating apparatus 156 contacts and separates the rollers of the processing liquid coating unit for each recording medium so as not to contaminate the processing liquid coating conveyance cylinder (processing liquid drum 154). It is preferable. The treatment liquid drum 154 conveys the recording medium 124 with a holding claw that holds the tip of the recording medium 124. As a result, the recording medium 124 can be conveyed at high speed, and the occurrence of paper conveyance jams can be reduced.

Note that the processing liquid applied to the recording medium 124 may be dried by providing an IR heater and a hot air jet nozzle on the outer periphery of the processing liquid drum 154 so as to face the peripheral surface. When an IR heater or a warm air ejection nozzle is provided, the IR heater is controlled to a high temperature (for example, 180 ° C.), and the warm air ejection nozzle generates a high temperature (for example, 70 ° C.) of warm air at a constant air volume (for example, 9 m). ³ / min) and sprayed toward the recording medium 124. By the heating by the IR heater and the hot air jet nozzle, moisture in the solvent of the processing liquid is evaporated, and a thin film layer of the processing liquid is formed on the recording surface of the recording medium 124. By thinning the treatment liquid in this way, the dots of ink that are ejected by the drawing unit 116 come into contact with the recording surface of the recording medium 124 to obtain the required dot diameter, and the thinned treatment liquid component Reacts with the colorant to cause aggregation of the color material, and an effect of fixing to the recording surface of the recording medium 124 is easily obtained. The processing liquid drum 154 may be controlled to a predetermined temperature (for example, 50 ° C.).

  Further, the treatment liquid contains an aggregating agent that aggregates the components in the ink composition applied by the drawing unit 116.

  The aggregating agent may be a compound capable of changing the pH of the ink composition, a polyvalent metal salt, or polyallylamines. In the present embodiment, from the viewpoint of the cohesiveness of the ink composition, a compound that can change the pH of the ink composition is preferable, and a compound that can lower the pH of the ink composition is more preferable. Preferred examples of the compound capable of lowering the pH of the ink composition include highly water-soluble acidic substances (phosphoric acid, oxalic acid, malonic acid, citric acid, derivatives of these compounds, and salts thereof).

  As described above, as the flocculant, an acidic substance having high water solubility is preferable, and an organic acid is preferable and an organic acid having a valence of 2 or more is more preferable from the viewpoint of improving the aggregation property and fixing the entire ink. Furthermore, an acidic substance having a valence of 2 to 3 is particularly preferable. As the divalent or higher organic acid, an organic acid having a first pKa of 3.5 or less is preferable, and an organic acid of 3.0 or less is more preferable. Specifically, phosphoric acid, oxalic acid, malonic acid, Preferred examples include citric acid.

  In the flocculant, the acidic substance may be used alone or in combination of two or more. Thereby, cohesion can be improved and the whole ink can be fixed. The content of the flocculant for aggregating the ink composition in the treatment liquid is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and still more preferably 5 to 40% by mass. is there. Further, it is preferable that the pH (25 ° C.) of the ink composition is 8.0 or more and the pH (25 ° C.) of the treatment liquid is in the range of 0.5 to 4. As a result, it is possible to increase the image density, resolution, and speed of inkjet recording.

  Further, the processing liquid can contain other additives. These additives include anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, antiseptics, anti-fungal agents, pH adjusters, surface tension adjusters, antifoaming agents, Well-known additives, such as a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, and a chelating agent, are mentioned.

  As described above, in this embodiment, the configuration in which the application method using the roller is applied is exemplified, but the application of the treatment liquid is not limited to the application method, and is performed by applying a known method such as an inkjet method or an immersion method. be able to. The coating method can be performed by a known coating method using a bar coater, an extrusion die coater, an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or the like.

  The treatment liquid application step may be provided either before or after the ink application step using the ink composition. In the present embodiment, an aspect in which the ink application process is provided after the treatment liquid is applied in the treatment liquid application process is preferable. Specifically, before applying the ink composition, a treatment liquid for aggregating the pigment and / or self-dispersing polymer particles in the ink composition is applied on the recording medium 124 in advance. A mode in which an image is formed by applying an ink composition so as to come into contact with the treatment liquid applied on the medium 124 is preferable. Thereby, inkjet recording can be speeded up, and an image with high density and resolution can be obtained even at high speed recording.

The amount of the treatment liquid applied is not particularly limited as long as the ink composition can be aggregated. However, the amount of the aggregation agent applied is preferably an amount that makes the amount of the aggregation agent 0.1 g / m ² or more. Especially, the quantity from which the provision amount of a flocculant will be 0.2-0.7 g / m < ² > is preferable. When the applied amount of the flocculant is 0.1 g / m ² or more, good high-speed flocculence can be maintained according to various usage forms of the ink composition. Further, it is preferable that the amount of the flocculant applied is 0.7 g / m ² or less because the surface properties of the applied recording medium are not adversely affected (such as a change in gloss).

  The processing liquid application unit 114 records the processing liquid while measuring the processing liquid by the processing liquid coating device 156 while holding and transporting the leading end portion of the recording medium 124 by the holding means 155 provided on the outer peripheral surface of the processing liquid drum 154. A treatment liquid is applied to the medium 124.

  The recording medium 124 to which the processing liquid is applied by the processing liquid application unit 114 is conveyed to the next drawing unit 116 by the intermediate conveyance unit (first transfer cylinder conveyance unit) 126. The recording medium 124 is held such that its leading end is held by a holding claw (not shown) of the first transfer drum conveying means 126, and is conveyed so that the recording surface faces inward and the back surface is convex along the guide member 127. Is done.

  Further, the first transfer drum transport means 126 has hot air drying means (not shown) inside (near the rotation axis), and blows hot air on the recording surface (front surface) side of the recording medium 124 facing inward during transport. The treatment liquid applied to the surface is dried. Thereby, when ink is ejected onto the recording medium 124 in the drawing unit 116, movement of the landing ink on the recording medium 124 at the time of ink adhesion is prevented.

  The drawing drum 170 of the drawing unit 116 holds the leading end portion of the recording medium 124 conveyed by the first transfer drum conveying unit 126 by the holding unit 171 provided on the outer peripheral surface of the drawing drum 170 and the outer periphery of the drawing drum 170. The recording medium 124 is sucked and fixed to the outer peripheral surface of the drawing drum 170 by a suction hole provided on the surface and conveyed. Then, water-based ultraviolet curable ink is applied from the inkjet heads 172M, 172K, 172C, and 172Y toward the surface (recording surface) of the recording medium 124 fixed to the outer peripheral surface of the drawing drum 170, to which the processing liquid is applied. Dropped.

  Here, the ink (aqueous ultraviolet curable ink) used in the present invention will be described.

  The aqueous ultraviolet curable ink includes a pigment, polymer particles, and a water-soluble polymerizable compound that is polymerized by active energy rays. Thereby, it can be hardened by irradiating with ultraviolet rays, and has excellent abrasion resistance and high film strength.

  The ink composition in the present invention contains a pigment, and can be constituted using a dispersant, a surfactant, and other components as necessary. The ink composition contains at least one pigment as a color material component. There is no restriction | limiting in particular as a pigment, According to the objective, it can select suitably, For example, any of an organic pigment and an inorganic pigment may be sufficient. The pigment is preferably a pigment that is almost insoluble or hardly soluble in water from the viewpoint of ink colorability. The pigment is preferably a water-dispersible pigment in which at least a part of its surface is coated with a polymer dispersant.

  The ink composition of the present invention can contain at least one dispersant. The dispersant for the pigment may be either a polymer dispersant or a low molecular surfactant type dispersant. The polymer dispersant may be either a water-soluble dispersant or a water-insoluble dispersant.

  The weight average molecular weight of the polymer dispersant is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, still more preferably 5,000 to 40,000, particularly preferably. 10,000 to 40,000.

  The acid value of the polymer dispersant is preferably 100 KOHmg / g or less from the viewpoint of good aggregation when the treatment liquid comes into contact. Furthermore, the acid value is more preferably 25 to 100 KOH mg / g, further preferably 25 to 80 KOH mg / g, and particularly preferably 30 to 65 KOH mg / g. When the acid value of the polymer dispersant is 25 or more, the stability of self-dispersibility is improved.

  The polymer dispersant preferably contains a polymer having a carboxyl group from the viewpoint of self-dispersibility and aggregation rate when the treatment liquid comes into contact, and the polymer dispersant has a carboxyl group and an acid value of 25 to 80 KOHmg / g. More preferably.

  In the present embodiment, from the viewpoint of light resistance and quality of the image, it is preferable to include a pigment and a dispersant, more preferably to include an organic pigment and a polymer dispersant, and further to include an organic pigment and a carboxyl group. It is particularly preferred to contain a polymer dispersant. Moreover, it is preferable that a pigment is coat | covered with the polymer dispersing agent which has a carboxyl group from a cohesive viewpoint, and is water-insoluble. Furthermore, from the viewpoint of cohesiveness, it is preferable that the acid value of the self-dispersing polymer particles described below is smaller than the acid value of the polymer dispersant.

  The average particle size of the pigment is preferably 10 to 200 nm, more preferably 10 to 150 nm, and even more preferably 10 to 100 nm. When the average particle diameter is 200 nm or less, the color reproducibility is good, and the droplet ejection characteristics when droplets are ejected by the ink jet method are good, and when it is 100 nm or less, the light resistance is good. Further, the particle size distribution of the color material is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Two or more color materials having a monodisperse particle size distribution may be mixed and used.

  The average particle size and particle size distribution of the pigment are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device UPA-EX150 (manufactured by Nikkiso Co., Ltd.). Is.

  You may use a pigment individually by 1 type or in combination of 2 or more types. The content of the pigment in the ink composition is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, and more preferably 5 to 20% by mass with respect to the ink composition from the viewpoint of image density. Is more preferable, and 5 to 15% by mass is particularly preferable.

(Polymer particles)
The ink composition in the invention can contain at least one kind of polymer particles. The polymer particles have a function of fixing the ink composition by increasing the viscosity of the ink by aggregation and dispersion instability when contacted with a treatment liquid described later or a dried region thereof. It is possible to further improve the fixing property of an object to a recording medium and the scratch resistance of an image.

  In order to react with the aggregating agent, polymer particles having an anionic surface charge are used, and generally known latex is used as long as sufficient reactivity and ejection stability are obtained. It is preferable to use polymer particles.

(Self-dispersing polymer particles)
The ink composition in the invention preferably contains at least one kind of self-dispersing polymer particles as polymer particles. This self-dispersing polymer has a function of fixing the ink composition by destabilizing and agglomerating and aggregating the ink to increase the viscosity of the ink when it comes into contact with a treatment liquid described later or a dried region thereof. Fixability of the composition to a recording medium and image scratch resistance can be further improved. Self-dispersing polymers are also preferred resin particles from the viewpoints of ejection stability and liquid stability (particularly dispersion stability) of the system containing the pigment.

  Self-dispersing polymer particles are water-insoluble polymers that can be dispersed in an aqueous medium by the functional groups (especially acidic groups or salts thereof) of the polymer itself in the absence of other surfactants. Means water-insoluble polymer particles which do not contain free emulsifiers.

  The acid value of the self-dispersing polymer in the present invention is preferably 50 KOHmg / g or less from the viewpoint of good cohesiveness when the treatment liquid comes into contact. Furthermore, the acid value is more preferably 25 to 50 KOH mg / g, and further preferably 30 to 50 KOH mg / g. When the acid value of the self-dispersing polymer is 25 or more, the stability of the self-dispersing property is improved.

  The self-dispersing polymer particles in the present invention preferably contain a polymer having a carboxyl group from the viewpoint of self-dispersibility and agglomeration speed when the treatment liquid comes into contact, and have a carboxyl group and an acid value of 25 to 25. More preferably, it contains a polymer of 50 KOH mg / g, more preferably a polymer having a carboxyl group and an acid value of 30 to 50 KOH mg / g.

  The molecular weight of the water-insoluble polymer constituting the self-dispersing polymer particles is preferably 3,000 to 200,000, more preferably 5,000 to 150,000 in terms of weight average molecular weight, and 10,000 to 10,000. More preferably, it is 100,000. By setting the weight average molecular weight to 3,000 or more, the amount of water-soluble components can be effectively suppressed. Moreover, self-dispersion stability can be improved by making a weight average molecular weight into 200,000 or less.

  The weight average molecular weight is measured by gel permeation chromatography (GPC). For GPC, HLC-8220GPC (manufactured by Tosoh Corporation) is used, and as columns, TSKgeL SuperHZM-H, TSKgeL SuperHZ4000, TSKgeL SuperHZ2000 (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm) are used as eluents. Use THF (tetrahydrofuran). As conditions, the sample concentration was 0.35 / min. The flow rate is 0.35 ml / min. The sample injection volume is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used. In addition, calibration curves are manufactured by Tosoh Corporation, “Standard sample TSK standard, polysrene”, “F-40”, “F-20”, “F-4”, “F-1”, “A-5000”. , “A-2500”, “A-1000”, “n-propylbenzene”.

  The average particle size of the self-dispersing polymer particles is preferably in the range of 10 nm to 400 nm, more preferably in the range of 10 to 200 nm, and still more preferably in the range of 10 to 100 nm. When the volume average particle size is 10 nm or more, the production suitability is improved, and when it is 1 μm or less, the storage stability is improved.

  The average particle size and particle size distribution of the self-dispersing polymer particles are measured by the dynamic light scattering method using Nanotrac particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.). Is required.

  The self-dispersing polymer particles can be used singly or in combination of two or more. The content of the self-dispersing polymer particles in the ink composition is preferably 1 to 30% by mass with respect to the ink composition from the viewpoint of aggregation rate and image glossiness, and 5 to 15 More preferably, it is mass%.

  In addition, the content ratio of the pigment and the self-dispersing polymer particles in the ink composition (for example, water-insoluble pigment particles / self-dispersing polymer particles) is 1 / 0.0 from the viewpoint of image scratch resistance. 5 to 1/10 is preferable, and 1/1 to 1/4 is more preferable.

(Polymerizable compound)
The ink composition in the present invention can contain at least one water-soluble polymerizable compound that is polymerized by active energy rays.

  As the polymerizable compound, a nonionic or cationic polymerizable compound is preferable in that the reaction between the flocculant, the pigment, and the polymer particles is not hindered. The term “water-soluble” means that it can be dissolved in water at a certain concentration or higher, and it can be dissolved in water-based ink (preferably uniformly). Further, the solubility may be increased by adding a water-soluble organic solvent, and it may be dissolved (desirably uniformly) in the ink. Specifically, the solubility in water is preferably 10% by mass or more, and more preferably 15% by mass or more.

  As the polymerizable compound, a nonionic or cationic polymerizable compound is preferable in that the reaction between the flocculant, the pigment, and the polymer particles is not hindered, and the solubility in water is 10% by mass or more (more preferably 15% by mass or more). The polymerizable compound is preferable.

  As the polymerizable compound in the present invention, a polyfunctional monomer is preferable from the viewpoint of enhancing scratch resistance, and a bifunctional to hexafunctional monomer is preferable, and from the viewpoint of compatibility between solubility and scratch resistance, bifunctional to tetrafunctional. Are preferred.

  A polymeric compound can be contained individually by 1 type or in combination of 2 or more types.

  The content of the polymerizable compound in the ink composition is preferably 30 to 300% by mass, more preferably 50 to 200% by mass, based on the total solid content of the pigment and the self-dispersing polymer particles. When the content of the polymerizable compound is 30% by mass or more, the image strength is further improved and the image has excellent scratch resistance, and when it is 300% by mass or less, it is advantageous in terms of pile height.

  At least one of the ink composition and the treatment liquid further includes an initiator that initiates polymerization of the polymerizable compound by active energy rays.

(Initiator)
The ink composition in the present invention may contain at least one initiator that initiates polymerization of the polymerizable compound by active energy rays with or without being contained in the treatment liquid. A photoinitiator can be used individually by 1 type or in mixture of 2 or more types or using together with a sensitizer.

  The initiator can contain a compound capable of initiating a polymerization reaction by active energy rays as appropriate. For example, the initiator starts generation of active species (radicals, acids, bases, etc.) by radiation or light, or electron beams. An agent (for example, a photopolymerization initiator) can be used.

  When the initiator is contained, the content of the initiator in the ink composition is preferably 1 to 40% by mass and more preferably 5 to 30% by mass with respect to the polymerizable compound. When the content of the initiator is 1% by mass or more, the scratch resistance of the image is further improved, which is advantageous for high-speed recording, and when it is 40% by mass or more, it is advantageous in terms of ejection stability.

(Water-soluble organic solvent)
The ink composition in the invention can contain at least one water-soluble organic solvent. The water-soluble organic solvent can obtain the effect of preventing drying, wetting or promoting penetration. In order to prevent drying, the ink adheres to and drys at the ink discharge port of the ejection nozzle and is used as an anti-drying agent to prevent clogging. For drying prevention and wetting, the vapor pressure is lower than that of water. A water-soluble organic solvent is preferred. Further, for penetration promotion, it can be used as a penetration enhancer that enhances ink permeability to paper.

  The drying inhibitor is preferably a water-soluble organic solvent having a vapor pressure lower than that of water.

  Anti-drying agents may be used alone or in combination of two or more. The content of the drying inhibitor is preferably in the range of 10 to 50% by mass in the ink composition.

  The penetration accelerator is suitable for the purpose of allowing the ink composition to penetrate better into the recording medium (printing paper or the like). A penetration enhancer may be used individually by 1 type, or may be used together 2 or more types. The content of the penetration enhancer is preferably in the range of 5 to 30% by mass in the ink composition. Moreover, it is preferable to use the penetration enhancer within a range that does not cause image bleeding and paper loss (print-through).

(water)
The ink composition contains water, but the amount of water is not particularly limited. Among these, the preferable content of water is 10 to 99% by mass, more preferably 30 to 80% by mass, and still more preferably 50 to 70% by mass.

(Other additives)
The ink composition in the present invention can be constituted using other additives in addition to the above components. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.

  Returning to FIG. 3 again, the drawing unit 116 ejects droplets of the corresponding color ink from the inkjet heads 172M, 172K, 172C, and 172Y toward the recording surface of the recording medium 124 held in close contact with the drawing drum 170. As a result, the ink comes into contact with the treatment liquid applied to the recording surface in advance by the treatment liquid application unit 114, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. As a result, the color material flow on the recording medium 124 is prevented, and an image is formed on the recording surface of the recording medium 124.

  The amount of ink droplets ejected from each of the inkjet heads 172M, 172K, 172C, and 172Y is preferably 1 to 10 pl (picoliter) and more preferably 1.5 to 6 pl from the viewpoint of obtaining a high-definition image. preferable. In addition, from the viewpoint of improving the unevenness of the image and the connection between the continuous gradations, it is also effective to discharge different droplet amounts in combination, and the present invention is suitably applied even in such a case.

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

  The drawing unit 116 configured as described above can perform drawing on the recording medium 124 in a single pass.

  The recording medium 124 on which an image is formed by the drawing unit 116 is transferred from the drawing drum 170 to the drying drum 176 of the drying unit 118 via the intermediate conveyance unit (second transfer cylinder conveyance unit) 128. The second transfer drum transport unit 128 holds the leading end of the recording medium 124 received from the drawing drum 170 by a holding claw (not shown), the recording surface of the recording medium 124 faces inward, and the back side is a guide member. 129 is conveyed so as to have a convex shape.

  The second transfer drum transport means 128 has a hot air drying means (drying means) (not shown) inside, and blows hot air on the recording surface side of the recording medium 124 facing the inside during the conveyance to the surface. The ejected ink is dried. As a result, since ink can be dried immediately after ink ejection, it becomes easy to reduce the clogging of the recording medium 124 due to ink permeation, and the occurrence of suction flaws at the time of suction restraint in the drying drum 176 in the drying unit 118 is suppressed. It becomes easy to do.

  The drying unit 118 (drying unit) is a mechanism for drying moisture contained in the solvent separated by the color material aggregation action, and faces the drying drum 176 and the outer peripheral surface of the drying drum 176 as shown in FIG. It is composed of hot air drying means 182 in which a plurality of combinations of IR heaters and fans are arranged at positions. Further, a blowing unit 180 (adsorption assisting unit) is provided on the upstream side (in the rotation direction of the drying drum 176) of the plurality of hot air drying units 182 so as to face the outer periphery of the drying drum 176.

  Similar to the processing liquid drum 154, the drying drum 176 includes a claw-shaped holding unit (gripper) 177 on the outer peripheral surface thereof, and the holding unit 177 can hold the leading end of the recording medium 124. Further, the drying drum 176 has a plurality of suction holes on the outer peripheral surface thereof, and the recording medium 124 is attracted to the outer peripheral surface of the drying drum 176 by negative pressure and restrained so as to be in close contact with the recording medium. The recording medium 124 is dried by applying hot air from the hot air jet nozzle of the hot air drying means 182 to the recording medium 124 constrained by the drying drum 176 in this way.

  This prevents the occurrence of cockle. Further, by causing the recording medium 124 to be in close contact with the outer peripheral surface of the drying drum 176, it is possible to prevent the occurrence of jam and paper burning due to the recording medium 124 coming into contact with the hot air drying means 182.

The hot air ejection nozzle of the hot air drying means 182 is configured to blow hot air controlled at a predetermined temperature (for example, 50 ° C. to 70 ° C.) toward the recording medium 124 at a constant air volume (12 m ³ / min). Each IR heater is controlled to a predetermined temperature (for example, 180 ° C.). By these hot air jet nozzles and IR heaters, moisture contained in the recording surface of the recording medium 124 held on the drying drum 176 is evaporated, and drying processing is performed. At that time, since the drying drum 176 of the drying unit 118 is structurally separated from the drawing drum 170 of the drawing unit 116, in the inkjet heads 172M, 172K, 172C, 172Y, the head meniscus portion is dried by thermal drying. Ink ejection failure can be reduced. Further, there is a degree of freedom in setting the temperature of the drying unit 118, and an optimal drying temperature can be set.

  In addition, it is preferable to discharge | evaporate the evaporated water | moisture content outside with the air by the discharge means which abbreviate | omitted illustration. Further, the collected air may be cooled by a cooler (radiator) or the like and collected as a liquid.

  Further, it is preferable that the outer peripheral surface of the drying drum 176 is controlled to a predetermined temperature. Drying is accelerated by heating from the back surface of the recording medium 124, and image destruction during fixing can be prevented. The range of the surface temperature of the drying drum 176 is preferably 50 ° C. or higher, more preferably 60 ° C. or higher. The upper limit is not particularly limited, but is preferably 75 ° C. or lower from the viewpoint of safety of maintenance work such as cleaning ink adhering to the surface of the drying drum 176 (preventing burns due to high temperature).

  The drying drum 176 is preferably heated to a predetermined temperature before the recording medium 124 is conveyed. By drying the drying drum 176, drying can be promoted, so that image destruction can be prevented and cuckling can be prevented. The heating temperature is preferably in the same temperature range as the surface temperature of the drying drum 176.

  Heating is preferably performed at a predetermined temperature in the sucked state in order to prevent a temperature drop when sucked. In addition, when heating is performed without suction, it is preferable to perform heating so that the temperature is higher than a predetermined temperature in consideration of a decrease in temperature at the time of suction. In addition, the recording medium 124 is held so that the recording surface faces outward (that is, in a state where the recording surface of the recording medium 124 is curved so as to be a convex side), and is dried while being rotated and conveyed. The occurrence of wrinkles and floats 124 can be prevented, and uneven drying due to these can be reliably prevented.

  The air blowing means 180 provided on the upstream side of the hot air drying means 182 is for assisting the adsorption of the recording medium 124 to the drying drum 176. The blowing unit 180 blows in an oblique direction toward the rear end side of the recording medium 124 so as to be applied obliquely toward the end portion side in the width direction of the recording medium 124, and further controls to increase the wind force at the rear end. . As a result, the sheet is prevented from floating at the rear end of the recording medium 124, and the recording medium 124 is picked up by suction to enable uniform drying and uniform suction. In this way, by using the suction assisting means that is not in contact with the recording medium 124 as the air blowing means 180, when the suction assist is performed using the contact means, the ink that has not yet dried on the recording medium 124 is contacted with the contact means. It is possible to prevent image defects from being transferred to the image.

  The suction force of the drying drum 176 can be expressed by (opening area) × (pressure per unit area). The suction force can be increased by increasing the area occupied by the suction holes in the recording medium suction holding region, that is, the aperture ratio.

  In addition, the opening ratio of the suction holes provided on the outer peripheral surface of the drying drum 176 is preferably 1% or more and 75% or less with respect to the contact area between the outer peripheral surface of the drying drum 176 and the recording medium 124. This is because if the aperture ratio is less than 1%, the expansion deformation of the recording medium 124 due to water absorption after recording cannot be sufficiently suppressed, and the drying drum 176 itself is also warmed. Drying is also promoted by contact, but if the aperture ratio exceeds 75%, the contact area between the back surface of the recording medium 124 and the outer peripheral surface of the drying drum 176 decreases, so that the recording medium 124 is held by suction. However, sufficient drying performance cannot be obtained, and the cockle is also deteriorated.

  Therefore, by setting the opening ratio of the suction holes on the outer peripheral surface of the drying drum 176 to 1% or more and 75% or less, it is possible to prevent the suppression of cockle and improve the drying performance.

  The aperture ratio is set by the diameter of the suction holes, the hole pitch, the shape and arrangement of the holes. The hole diameter is preferably designed to be not less than 0.4 mm and not more than 1.5 mm so as not to cause a dent mark (suction mark) of the recording medium 124 due to negative pressure suction. The hole pitch is preferably from 0.1 mm to 5 mm in order to prevent thermal deformation of the outer peripheral surface of the drying drum 176 and to ensure rigidity. This is because if the distance between the holes is too far away, the effect of suppressing the deformation of the recording medium is insufficient and the generation of wrinkles cannot be suppressed so much. Further, the shape of the suction hole is preferably a shape with rounded corners because stress is concentrated at the corners if there are corners (acute angles).

  In the rotary conveyance body, the deformation amount of the recording medium 124 due to the adsorption pressure is larger in the axial direction than in the circumferential direction. Therefore, the suction hole is formed in an elliptical shape or a long hole shape in which the circumferential direction is the major axis direction and the axial direction is the minor axis direction, so that the circumferential deformation and the axial deformation of the recording medium 124 are made uniform. You can also.

  Further, it is held on the outer peripheral surface of the drying drum 176 so that the recording surface of the recording medium 124 faces outward (that is, in a state where the recording surface of the recording medium 124 is curved so as to be convex), and is rotated and conveyed. While drying, it is possible to prevent the recording medium 124 from wrinkling and floating, and to reliably prevent drying unevenness due to these.

  The recording medium 124 that has been dried by the drying unit 118 is transferred from the drying drum 176 to the third transfer cylinder transport unit 130 that constitutes the fixing unit 120.

  The recording medium 124 is held at its leading end by a holding claw (not shown) of the third transfer drum transport means 130, the recording surface faces inward, the rear end side is free, and the back side faces the guide member 131. And is conveyed so as to have a convex shape (a concave shape on the recording surface side).

  In other words, the third transfer drum transport means 130 (transfer drum transport means) does not adsorb and restrain the recording medium 124, and thus, the drying unit 118 is dried while being sucked and restrained by the drying drum 176. The restraint (adsorption) of the recorded recording medium 124 is once released, and the recording medium 124 is bent and corrected in the reverse direction, thereby flattening the recording medium 124 and preventing curling.

  Further, as described above, the third transfer drum transport unit 130 includes the ultraviolet light source 190 therein, and forms the fixing unit 120 (fixing unit). As described above, the ultraviolet light source 190 is disposed inside the third transfer drum transport means 130, and the recording surface of the recording medium 124 facing inward during the transport is irradiated with the ultraviolet light, and the water droplets hitting the surface are ejected. The UV curable ink is cured. As a result, unevenness caused by the suction holes of the drying drum 176 in the drying unit 118 can be made uniform.

  As described above, the ultraviolet light source 190 is arranged inside the third transfer drum transport unit 130 to form the fixing unit 120 (fixing unit), so that the ultraviolet light source usually faces the rear stage of the third transfer drum transport unit 130. Although the arranged fixing drum is provided, it becomes unnecessary and one drum can be reduced. Furthermore, since the ultraviolet light source is provided inside the transfer drum having a structure simpler than that of the drum, the maintenance becomes easier than the case where the ultraviolet light source is arranged inside the drum.

  In addition, the recording medium 124 is temporarily released from the adsorption to the drying drum 176 in the previous stage, and further bent and cured and fixed in the opposite direction, thereby reducing paper curl variation and making the curl direction the same. Therefore, the integration property of the subsequent recording medium 124 is improved. That is, since the recording surface 124 of the recording medium 124 is cured and fixed so that the recording surface side is concave and the back surface side thereof is convex, when the recording medium 124 comes one after another when the recording surface side is accumulated, Since the lower recording medium 124 has a concave shape, the integration is good.

  Further, as shown in FIG. 3, a cover 184 (cover member) that covers the drying unit 118 from the third transfer drum transport unit 130 (fixing unit 120) is attached, and a fan 185 is provided on the third transfer drum transport unit 130 side. A (first fan) may be attached, and the air heated by the ultraviolet light source 190 may be sent to the hot air drying means 182 of the drying unit 118 by the fan 185.

  Thus, by efficiently using the heat generated in the fixing unit 120 (the ultraviolet light source 190) in the drying unit 118, it is possible to reduce the power consumption of the hot air drying means 182 and improve the thermal efficiency. Become.

  In addition, as shown in FIG. 3, it is preferable to provide a plurality of ultraviolet light sources 190 for curing the aqueous ultraviolet curable ink. By continuously irradiating ultraviolet rays with a plurality of ultraviolet light sources 190 in this way, it becomes possible to reduce the irradiation intensity of each ultraviolet light source 190 and earn curing conditions in the ultraviolet irradiation time. The amount of heat generated can be reduced and the cost can be reduced.

  The ultraviolet light source 190 is not particularly limited, and for example, a metal halide lamp, a high-pressure mercury lamp, a black light, a cold cathode tube, a UV-LED, or the like is preferably used.

The peak wavelength of ultraviolet rays irradiated by the ultraviolet light source 190 is preferably 200 to 600 nm, more preferably 300 to 450 nm, and still more preferably 350 to 450 nm, although it depends on the absorption characteristics of the ink composition.
The irradiation energy of the ultraviolet light source 190, preferably 2000 mJ / cm ² or less, more preferably from 10 to 2000 mJ / cm ^2, more preferably from 20~1000mJ / cm ^2, particularly preferably 50 to 800 mJ / Cm ² .
In the ink jet recording apparatus of the present invention, it is appropriate to irradiate the recording surface of the recording medium with ultraviolet rays for 0.01 to 10 seconds, more preferably for 0.1 to 2 seconds.

  Next, other embodiments will be described. In the embodiment described below, heat efficiency is improved by reusing heat generated in the fixing unit 120 configured by the third transfer cylinder conveying unit 130 in the drying unit 118.

  FIG. 4 shows an enlarged view of the fixing unit 120 and the drying unit 118 in another embodiment. FIG. 4A is a configuration diagram showing a fixing unit 120 and a drying unit 118 and a mechanism for improving thermal efficiency, and FIG. 4B shows a structure of an ultraviolet light source.

  In FIG. 4A, a cover 184 is provided so as to cover the upper part of the fixing unit 120 (third transfer drum transport unit 130) and the drying unit 118. The cover 184 is formed of a heat insulating member, and can be sent to the drying unit 118 and reused without releasing the heat generated in the fixing unit 120.

  The cover 184 has a partition plate 184a that forms separate spaces each including one of each hot air drying means 182 disposed on the top of the drying drum 176. A fan 185 (first fan) is provided on the side closest to the fixing unit 120, and an exhaust fan 186 is provided on the side farthest from the fixing unit 120. Further, the flow of hot air is corrected so that the hot air blown from the hot air drying means 182 to the recording medium 124 (not shown here) on the outer peripheral surface of the drying drum 176 is reused by the next hot air drying means 182. A rectifying plate (guide plate) 183 is provided in each hot air drying means 182.

  In addition, an ultraviolet light source 190 is disposed inside the third transfer drum transport unit 130. Thus, by providing the ultraviolet light source 190 inside, unevenness due to the suction hole of the drying drum 176 can be prevented.

  As illustrated in FIG. 4B, the ultraviolet light source 190 includes an ultraviolet irradiation lamp 191, a reflector 193, and a fan 195 (second fan). The fan 195 (second fan) is for blowing air heated by the heat of the ultraviolet irradiation lamp 191 to the recording medium 124 as hot air. That is, the fan 195 generates a wind flow as shown by an arrow B in FIG. 4B, and thereby blows air to the recording surface side of the recording medium 124 conveyed below the ultraviolet light source 190. This wind accelerates the drying of the recording medium 124 and allows the ultraviolet irradiation lamp 191 to be cooled.

  Also, as shown in FIG. 4A, a guide member 131 is disposed below the third transfer drum transport unit 130. Here, the heat insulating member is attached to the guide member 131, and the guide member 131 can be reused without releasing heat to the back side of the guide member 131.

  The hot air blown out toward the recording medium 124 from the ultraviolet light source 190 disposed inside the third transfer drum transport unit 130 is reflected by the guide member 131, and as indicated by an arrow A in the figure, the fixing unit 120. It flows toward the cover 184 provided on the upper side.

  This wind is absorbed by the fan 185 (first fan) and sent to the hot air drying means 182 of the drying unit 118. In this way, the hot air hitting the recording medium 124 by the fixing unit 120 is sent to the drying unit 118 by the fan 185 and reused, so that power consumption can be reduced and thermal efficiency can be improved.

  Further, as indicated by an arrow indicating the direction of hot air blown from the ultraviolet light source 190 toward the guide member 131 in FIG. 4A, the recording medium 124 is irradiated with ultraviolet rays obliquely and the wind is also oblique. It is preferable to apply it from the direction because the hot air hitting the recording medium 124 can be easily reused.

  When hot air is applied perpendicularly to the recording medium 124, the heat from the reflected light gathers in the ultraviolet irradiation lamp 191 and accumulates heat, which has a detrimental effect that the life of the ultraviolet irradiation lamp 191 is shortened. The lifetime of the irradiation lamp 191 can be extended. The oblique direction is preferably arranged so that the ultraviolet rays and hot air are directed toward the drying unit 118. This is for preventing leakage of ultraviolet rays to the outside of the machine, improving heat accumulation efficiency in the drying unit 118, and reducing the installation range of the cover 184 formed of the heat insulating member.

  Further, since hot air containing moisture that dries the recording medium 124 flows in the cover 184, there is a risk that image condensation may occur due to condensation and dripping of moisture onto the recording medium 124. Therefore, in order to prevent this, it is preferable to cover the inner surface of the cover 184 with a member that absorbs water.

  In addition, the cover 184 formed of a heat insulating member may be appropriately provided with an intake hole 184b so as to take in external dry air.

  Note that it is desirable to use hot air that is directed from the downstream side to the upstream side in the recording medium conveyance direction. This is because the drying air on the downstream side has a low water content and high drying efficiency. On the other hand, when the wind from the upstream to the downstream is reused, the wind with a large amount of water is reused, and the drying efficiency is reduced.

  The reused hot air is finally discharged out of the cover 184 by the exhaust fan 186. Thereby, it can suppress that the humidity in the cover 184 rises.

  FIG. 5 shows an enlarged view of the fixing unit 120 and the drying unit 118 in still another embodiment.

  FIG. 5A is a configuration diagram showing a fixing unit 120 and a drying unit 118 and a mechanism for improving thermal efficiency, and FIG. 5B shows a structure of an ultraviolet light source.

  This example also has substantially the same configuration as the example described above. That is, a cover 184 of a heat insulating member is formed so as to cover the upper part of the fixing unit 120 and the drying unit 118, and the inside of the cover 184 is partitioned by the partition plate 184 a for each hot air drying means 182 to absorb hot air from the fixing unit 120. A fan 185 (first fan) that feeds into the drying unit 118 and an exhaust fan 186 that discharges hot air after use are provided.

  In this example, the hot air generated by the ultraviolet light source 190 is not applied once to the recording medium and then sent to the drying unit 118 for reuse, but the hot air generated by the ultraviolet light source 190 is indicated by an arrow A in the figure. In this way, it is sent directly to the drying unit 118.

  As shown in FIG. 5B, the ultraviolet light source 190 of this example also includes an ultraviolet irradiation lamp 191, a reflector 193, and a fan 195 (second fan) as in the previous example. 195 (second fan) sucks the hot air generated by the ultraviolet irradiation lamp 191 and blows it to the side opposite to the recording medium 124 (not shown) as indicated by an arrow C in the figure.

  Thereby, the hot air generated by the ultraviolet light source 190 can be sent directly to the drying unit 118 via the fan 185 (first fan), and power consumption can be reduced and thermal efficiency can be improved. In this case, the heat collection efficiency is better than the reuse of hot air once hitting the recording medium.

  As described above in detail, according to the present embodiment, the transfer drum transporting unit is configured to release the suction constraint by the transfer drum transport unit following the drying drum after being dried by suction binding to the drying drum. Since curing and fixing are performed by the ultraviolet curing means arranged inside, even when aqueous ultraviolet curing ink is used, curing unevenness and fixing flaws can be suppressed and curing and fixing can be performed efficiently.

  Further, the thermal efficiency can be improved by reusing the hot air generated by the ultraviolet curing means disposed inside the transfer drum transport means in the immediately preceding drying section.

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

  DESCRIPTION OF SYMBOLS 100 ... Inkjet recording device, 112 ... Paper feed part, 114 ... Processing liquid provision part, 116 ... Drawing part, 118 ... Drying part, 120 ... Fixing part, 124 ... Recording medium, 126 ... Intermediate conveyance part (1st transfer cylinder conveyance) Means), 128... Intermediate conveyance section (second transfer cylinder conveyance means), 130... Intermediate conveyance section (third transfer cylinder conveyance means), 154... Processing liquid drum, 156. DESCRIPTION OF SYMBOLS ... Drying drum, 178 ... Solvent drying apparatus, 180 ... Air blowing means, 182 ... Hot air drying means, 184 ... Cover, 185 ... Fan, 190 ... Ultraviolet light source, 192 ... Paper discharge unit

Claims (11)

A liquid discharge head for discharging aqueous ultraviolet curable ink onto the recording surface of the recording medium;
The holding means formed on the outer peripheral surface holds the front end of the recording medium on which the water-based ultraviolet curable ink is ejected on the recording surface, and the back surface of the recording surface through a suction hole formed on the outer peripheral surface. A suction restraining cylinder that restrains and conveys the recording medium by adsorbing a side to the outer peripheral surface, and a hot air drying means that is disposed to face the outer peripheral surface of the suction restraining cylinder and blows hot air onto the recording medium. A constrained drying unit;
A transfer cylinder transport unit disposed on the downstream side of the constraining drying unit, configured to hold the tip of the recording medium and transport the recording medium in a state where the recording surface is curved in a concave shape; and the transfer cylinder transport unit A fixing unit having ultraviolet irradiation means for irradiating ultraviolet rays onto a recording surface of the recording medium which is disposed inside and conveyed by the transfer drum conveying means,
An ink jet recording apparatus comprising:   The inkjet recording apparatus according to claim 1, wherein a plurality of the ultraviolet irradiation units are arranged along a curved shape of the recording medium conveyed by the transfer drum conveying unit.   A cover member that covers the fixing unit and the upper part of the drying unit, and a first fan that blows air heated by heat generated by the ultraviolet irradiation means in a space between the cover member and the drying unit. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is an ink jet recording apparatus.   The inkjet recording apparatus according to claim 3, wherein the cover member includes a heat insulating member.   The inkjet according to any one of claims 1 to 4, wherein the transfer drum transport means includes a guide member for transporting the recording medium in a state where the recording surface side is curved in a concave shape. Recording device.   The inkjet recording apparatus according to claim 5, wherein the guide member includes a heat insulating member.   The ultraviolet irradiating means blows air heated by the heat generated by the ultraviolet irradiating means toward the recording medium conveyed by the transfer cylinder conveying means or toward the drying unit. The inkjet recording apparatus according to claim 1, further comprising a fan.   The exhaust fan for exhausting the air in the space formed between the cover member and the drying unit is installed on the most upstream side of the cover member in the recording medium conveyance direction. 8. The ink jet recording apparatus according to any one of 7 above.   The ink jet recording apparatus according to claim 3, wherein an inner surface of the cover member is covered with a member that absorbs moisture. An ink discharge step of discharging aqueous ultraviolet curable ink onto the recording surface of the recording medium;
The water-based ultraviolet curable ink holds the tip of the recording medium ejected onto the recording surface by holding means formed on the outer peripheral surface of the suction restraining cylinder, and the suction hole is formed through the suction hole formed on the outer peripheral surface. A constraining drying process in which the recording surface of the recording medium is dried by applying hot air while adsorbing and restraining the back surface side of the recording surface to the outer peripheral surface;
The recording medium dried in the constrained drying process is held inside the transfer drum transport means while being transported in a state in which the recording surface side is curved in a concave shape while the leading end is held by the transfer drum transport means. A fixing step of fixing the recording surface of the recording medium by irradiating with ultraviolet rays by means of ultraviolet irradiation means disposed in
An ink jet recording method comprising:   Covering the upper part of the transfer cylinder transporting means and the suction restraining cylinder with a cover member, air heated by the heat generated by the ultraviolet irradiation means is blown into a space formed between the cover member and the suction restraining cylinder. The inkjet recording method according to claim 10.

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