JP5147798B2 - Inkjet recording apparatus and method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and method, and more particularly, to an ink jet recording apparatus and method for recording an image with a water-based ink on a sheet (a permeable recording medium).

  When an image is recorded by an inkjet method using water-based ink (ink containing at least water and a color material) on paper, there is a problem that unevenness (cuckling) occurs on the paper. This is because there is a difference in the amount of water absorbed by the paper fibers between the area where the ink is adhered (image area) and the area where the ink is not adhered (non-image area), and the amount of elongation of the paper becomes uneven. Caused by

  In order to solve such a problem, Patent Document 1 discloses that a substantially transparent liquid mainly composed of water is applied to a non-image portion so that the amount of water in the non-image portion is close to the amount of water in the image portion. A method for suppressing cockle has been proposed.

  Patent Document 2 proposes a method of spraying steam on a printing surface as a technique for suppressing paper curling. This is because the ink on the surface is heated by the sprayed steam and the moisture contained in the ink penetrates into the inside of the paper, so that the moisture content on the front and back sides of the paper is the same and curling is suppressed. .

JP 2005-212371 A JP 2008-119998 A

  However, the method of Patent Document 2 has a drawback that curl cannot be suppressed even though curl can be suppressed. In addition, ink is insufficiently dried due to the spraying of steam on the printing surface, and roller offset (transfer of ink to the surface of the roller) and stacker blocking (transfer of ink to the upper paper when collected by stacking) , Sticking) occurs.

  On the other hand, the method of Patent Document 1 requires a separate means for applying a liquid to the non-image part, and has a drawback that the apparatus configuration is large and complicated.

  The present invention has been made in view of such circumstances, and an ink jet recording apparatus and method capable of recording an image with a water-based ink without causing roller offset or stacker blocking and without causing cuckling. provide.

  In order to achieve the above object, the invention according to claim 1 is a paper feeding unit that continuously feeds sheets of sheets, and an aqueous ink by an inkjet head on the surface of the paper fed from the paper feeding unit. A recording unit that records an image, a humidifying unit that humidifies the back surface of the paper on which the image is recorded on the front surface by the recording unit, and a heat roller on the front surface of the paper whose back surface is humidified by the humidifying unit An ink jet recording apparatus comprising: a heating / pressurizing unit that presses and presses the sheet and a recovery unit that stacks and collects the sheets heated and pressed by the heating / pressurizing unit. To do.

  According to the present invention, the sheet on which the image is recorded on the front surface by the recording unit is heated and pressurized by the heat roller being pressed against the surface by the heating and pressing unit after the back surface is humidified by the humidifying unit. In this way, by humidifying and pressurizing with a heat roller, the pressurization can be performed in a state where the rigidity of the paper is lowered, and the cockle can be corrected well. Further, by humidifying the back surface, drying of the ink on the front surface is not hindered. Thereby, generation | occurrence | production of roller offset and stacker blocking can also be prevented.

  In order to achieve the above object, the invention according to claim 2 is a first recording section for recording an image by ejecting water-based ink onto the surface of a sheet of paper with an inkjet head, and the image is recorded on the surface. A first humidifying unit that humidifies the back surface of the paper sheet, a first heating and pressurizing unit that heats and presses a heat roller against the front surface of the paper sheet whose back surface is humidified, and a front and back surface of the paper. A front / back reversing unit for reversing, a second recording unit for recording an image by ejecting water-based ink with an inkjet head on the reverse side of the reversed paper, and a surface of the paper on which the image is recorded on the back side An ink jet recording apparatus comprising: a second humidifying unit that humidifies; and a second heat and pressure unit that heats and presses a heat roller against a back surface of the paper whose surface is humidified. provide.

  According to the present invention, after the image is recorded on the front surface, the image is recorded on the back surface. That is, images are recorded on both sides of the paper. At this time, after the image is recorded on both sides of the paper, the surface opposite to the recording surface is humidified, and then the recording surface is heated and pressed by a heat roller to correct the cockle. In this way, by humidifying the surface opposite to the recording surface and applying heat and pressure, it is possible to heat and press in a state where the rigidity of the paper is lowered, and to correct the cockle well. Further, by humidifying the surface opposite to the recording surface, it is possible to prevent occurrence of roller offset and stacker blocking. Furthermore, after the image is recorded on the front surface, the image is recorded on the back surface in a state in which the cockle is corrected, so that a high-quality image can be recorded on both sides of the paper.

According to a third aspect of the present invention, in order to achieve the above object, the amount of water supplied to the back surface of the paper by the humidifying unit is 0.1 [g / m ² ] to 1.0 [g / m ² ]. 3. An ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is provided.

According to the present invention, the amount of water supplied to the back surface of the paper by the humidifying unit is set to 0.1 [g / m ² ] to 1.0 [g / m ² ]. As a result, the sheet can be heated and pressed in a rigid state necessary and sufficient to correct the cockle, and the occurrence of stacker blocking can also be prevented.

  The invention according to claim 4 is characterized in that, in order to achieve the object, the pressing force of the heat roller is 0.05 [MPa] to 0.5 [MPa]. An ink jet recording apparatus according to claim 1 is provided.

  According to the present invention, the pressing force of the heat roller at the heating and pressing unit is set to 0.05 [MPa] to 0.5 [MPa]. As a result, the cockle can be corrected satisfactorily and the occurrence of roller offset can be prevented.

  The invention according to claim 5 is characterized in that, in order to achieve the object, the temperature of the heat roller is 40 [° C.] to 80 [° C.]. An inkjet recording apparatus is provided.

  According to the present invention, the temperature of the heat roller in the heating and pressing unit is set to 40 [° C.] to 80 [° C.]. As a result, the cockle can be corrected satisfactorily and the occurrence of roller offset can be prevented.

  The invention according to claim 6 is characterized in that, in order to achieve the object, the liquid that humidifies the back surface of the paper in the humidifying section is water. An ink jet recording apparatus is provided.

  According to the present invention, the back surface of the paper is humidified with water. By humidifying with water, handling can be facilitated.

  The invention according to claim 7 is characterized in that, in order to achieve the above object, the liquid for humidifying the back surface of the paper in the humidifying section contains a surfactant and / or a preservative. An ink jet recording apparatus according to any one of 1 to 6 is provided.

  According to the present invention, a surfactant and / or a preservative is contained in the liquid that humidifies the back surface of the paper. By containing a surfactant, wetting and spreading of the liquid can be promoted, and by adding a preservative, generation of mold and the like can be suppressed.

  In order to achieve the above object, the invention according to claim 8 further includes a drying unit that dries the water-based ink ejected on the surface of the paper by the recording unit before humidifying by the humidifying unit. The inkjet recording apparatus according to claim 1, wherein the unit humidifies the back surface of the paper by applying wet air discharged from the drying unit to the back surface of the paper. I will provide a.

  According to the present invention, the paper on which the image is recorded on the front surface by the recording unit is humidified on the back surface by the humidifying unit after the ink is dried by the drying unit. At this time, in the humidification unit, the humid air discharged from the drying unit is applied to the back surface of the paper, and the back surface is humidified. Thereby, the ink can be sufficiently dried and the apparatus can be operated efficiently.

  The invention according to claim 9 is the ink jet recording apparatus according to any one of claims 1 to 8, wherein the water-soluble ink contains a thermoplastic resin in order to achieve the object. provide.

  According to the present invention, the water-soluble ink contains a thermoplastic resin.

  The invention according to claim 10 is characterized in that, in order to achieve the object, the water-soluble ink is an actinic ray curable ink. I will provide a.

  According to the present invention, the water-soluble ink is composed of actinic ray curable ink.

  According to an eleventh aspect of the invention, in order to achieve the above object, a first recording step of recording an image by ejecting water-based ink onto the surface of a sheet of paper with an ink jet head and recording the image on the surface A first humidifying step of humidifying the back surface of the paper sheet, a first heating and pressing step of heating and pressing a heat roller against the surface of the paper sheet whose back surface is humidified, and heat and pressure. A second recording step of recording an image by ejecting water-based ink onto the back surface of the paper with an inkjet head, and a second humidifying step of humidifying the surface of the paper on which the image is recorded on the back surface; There is provided an ink jet recording method comprising: a second heat-pressing step in which a heat roller is pressed and brought into contact with the back surface of the paper whose surface is humidified to heat and pressurize.

  According to the present invention, after the image is recorded on the front surface, the image is recorded on the back surface. That is, images are recorded on both sides of the paper. At this time, after the image is recorded on both sides of the paper, the surface opposite to the recording surface is humidified, and then the recording surface is heated and pressed by a heat roller to correct the cockle. In this way, by humidifying the surface opposite to the recording surface and applying heat and pressure, it is possible to heat and press in a state where the rigidity of the paper is lowered, and to correct the cockle well. Further, by humidifying the surface opposite to the recording surface, it is possible to prevent occurrence of roller offset and stacker blocking. Furthermore, after the image is recorded on the front surface, the image is recorded on the back surface in a state in which the cockle is corrected, so that a high-quality image can be recorded on both sides of the paper.

  According to a twelfth aspect of the present invention, in order to achieve the above object, the recovery is performed by laminating a predetermined number of sheets heated and pressed in the first heating and pressing step before the second recording step. The method according to claim 11, further comprising a step.

  According to the present invention, the paper on which image recording on the front surface is completed is collected in a state where it is once laminated, and then image recording on the back surface is performed. Thus, even if the sheets after the image recording are collected in a stacked state, they can be collected without causing stacker blocking.

According to the thirteenth aspect of the present invention, in order to achieve the above object, the amount of water supplied to the back surface of the paper in the first humidification step and the second humidification step is 0.1 [g / m ² ] -1 0.0 [g / m ² ], the pressing force of the heat roller in the first heating and pressing step and the second heating and pressing step is 0.05 [MPa] to 0.5 [MPa], and the temperature The inkjet recording method according to claim 11 or 12, wherein the temperature is 40 [° C] to 80 [° C].

According to the present invention, the amount of water supplied to the back surface of the paper in the first humidification step and the second humidification step is set to 0.1 [g / m ² ] to 1.0 [g / m ² ]. The pressing force of the heat roller in the first heating and pressing step and the second heating and pressing step is 0.05 [MPa] to 0.5 [MPa], and the temperature is 40 [° C.] to 80 [° C.]. Set to As a result, the sheet can be heated and pressed in a rigid state necessary and sufficient to correct the cockle, and the occurrence of stacker blocking can also be prevented.

  According to the present invention, it is possible to record an image with water-based ink on a sheet without causing roller offset or stacker blocking and without causing cuckling.

1 is an overall configuration diagram of a first embodiment of an ink jet recording apparatus according to the present invention. Schematic configuration diagram of humidifier Table showing experimental results 2 is an overall configuration diagram of a second embodiment of an ink jet recording apparatus according to the present invention.

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

[First Embodiment]
"Device configuration"
FIG. 1 is an overall configuration diagram of a first embodiment of an ink jet recording apparatus according to the present invention.

  The ink jet recording apparatus 10 is an ink jet recording apparatus that records a color image on a sheet of paper 14 using four colors of water-based inks of cyan (C), magenta (M), yellow (Y), and black (K). As shown in FIG. 1, mainly, a sheet feeding unit 20 that continuously feeds sheets of sheets 14 and a predetermined processing liquid is applied to the surface of the sheet 14 fed from the sheet feeding unit 20. A processing liquid application unit 30, a recording unit 40 that records an image by ejecting C, M, Y, and K ink droplets on the surface of the paper 14 to which the processing liquid is applied, and a paper 14 on which the image is recorded. A drying unit 50 for drying, a humidifying unit 60 for humidifying the back surface of the paper 14 after drying, a heating and pressing unit 70 for pressing and heating the heat roller against the paper 14 with the back surface humidified, and heating and pressing A collecting unit 80 that sequentially stacks and collects the pressed sheets 14 It is configured to include a.

  The processing liquid application unit 30, the recording unit 40, the drying unit 50, and the heating and pressurizing unit 70 are respectively provided with pressure drums (conveying drums) 34, 44, 54, and 74 as conveying means. Is wound around the peripheral surfaces of the pressure drums 34, 44, 54 and 74, and is conveyed while rotating each part of the treatment liquid applying unit 30, the recording unit 40, the drying unit 50, and the heating and pressing unit 70.

  Further, between the paper feeding unit 20 and the treatment liquid application unit 30, between the treatment liquid application unit 30 and the recording unit 40, between the recording unit 40 and the drying unit 50, and between the drying unit 50 and the heating and pressing unit 70. Between them, transfer cylinders (conveying drums) 32, 42, 52, 62 as conveying means are arranged, respectively, and the paper 14 is wound around the peripheral surfaces of the transferring cylinders 32, 42, 52, 62. Then, it is conveyed while rotating between each part.

  The impression cylinders 34, 44, 54, 74 and the transfer cylinders 32, 42, 52, 62 are alternately arranged, and are driven by motors (not shown) to rotate in opposite directions. That is, the impression cylinders 34, 44, 54, and 74 rotate in the counterclockwise direction in FIG. 1, and the transfer cylinders 32, 42, 52, and 62 rotate in the clockwise direction in FIG.

  Note that grippers G for gripping the leading end of the paper 14 are provided on the peripheral surfaces of the impression cylinders 34, 44, 54, 74 and the transfer cylinders 32, 42, 52, 62. The paper 14 is conveyed while the leading end is gripped by the gripper G. The gripper G is disposed at two peripheral surfaces (positions 180 degrees apart) of the impression cylinders 34, 44, 54, and 74 and the transfer cylinders 32, 42, 52, and 62, and continuously feeds the paper 14 that is supplied. Grasp in order. The impression cylinders 34, 44, 54, 74 and the transfer cylinders 32, 42, 52, 62 deliver and receive the paper 14 while synchronizing the position of the gripper G.

  The paper 14 is wound around the peripheral surface of the impression cylinders 34, 44, 54, 74 with the image recording surface (front surface) facing outside, and the transfer cylinders 32, 42, 52, No. 62 is wound around the circumferential surface so that the surface (back surface) opposite to the image recording surface is outside.

  The sheet 14 fed from the sheet feeding unit 20 is transferred to the pressure drum 34 of the processing liquid application unit 30 via the transfer cylinder 32, and recorded from the pressure cylinder 34 of the processing liquid application unit 30 via the transfer cylinder 42. Passed to the impression cylinder 44 of the section 40. Then, the pressure is transferred from the pressure drum 44 of the recording unit 40 to the pressure drum 54 of the drying unit 50 via the transfer drum 52, and from the pressure drum 54 of the drying unit 50 to the pressure drum of the heating and pressure unit 70 via the transfer drum 62. 74. Then, the pressure is transferred from the pressure drum 74 of the heating and pressing unit 70 to the collecting unit 80. In this series of conveyance processes, the paper 14 passes through the treatment liquid application unit 30, the recording unit 40, the drying unit 50, the humidification unit 60, and the heating and pressurization unit 70, and is subjected to necessary processing in each unit to obtain a surface (image). An image is formed on the recording surface.

  Hereinafter, the configuration of each unit (the paper feeding unit 20, the treatment liquid applying unit 30, the recording unit 40, the drying unit 50, the humidifying unit 60, the heating and pressing unit 70, and the collecting unit 80) of the ink jet recording apparatus 10 of the present embodiment. Explain in detail.

<Paper Feeder>
The paper supply unit 20 includes a paper supply device 22 and a paper supply tray 24, and continuously supplies the paper 14 one by one.

  The paper feeding device 22 feeds the paper 14 stored in a stacked state in a stacker (not shown) one by one from the upper side to the paper feeding tray 24 one by one.

  The sheet feed tray 24 sends out the sheets 14 fed one by one from the sheet feeder 22 toward the transfer cylinder 32.

  The paper 14 delivered from the paper feed tray 24 is transferred to the pressure drum 34 of the processing liquid application unit 30 via the transfer drum 32.

  The type of the paper 14 is not particularly limited, but here, a printing paper is used. Printing paper is classified into non-coated paper and coated paper depending on the presence or absence of a coating material (kaolin) applied to enhance smoothness and ink absorbability. Divided into paper, coated paper, and finely coated paper. Here, various coated papers are used.

<Processing liquid application part>
The processing liquid application unit 30 applies a predetermined processing liquid to the surface of the paper 14. The processing liquid application unit 30 applies a predetermined processing liquid to the pressure drum (processing liquid drum) 34 that conveys the paper 14 and the surface (image recording surface) of the paper 14 that is conveyed by the processing liquid drum 34. And an applicator 36.

  The processing liquid drum 34 receives the paper 14 from the transfer drum 32 (holds and receives the leading edge of the paper 14 with the gripper G), wraps around the peripheral surface, and rotates and conveys the paper 14. At this time, the processing liquid drum 34 receives the paper 14 from the transfer cylinder 32 with the surface of the paper 14 facing outside, and rotates and conveys the paper 14.

  The treatment liquid application device 36 is provided to face the peripheral surface of the treatment liquid drum 34, and applies a predetermined treatment liquid to the surface of the paper 14 that is rotated and conveyed by the treatment liquid drum 34. The processing liquid application device 36 applies (applies) the processing liquid to the surface of the paper 14 by pressing and abutting the application roller applied with the processing liquid on the peripheral surface against the peripheral surface of the paper 14.

  The treatment liquid application device 36 is not limited to this, and may be configured by an ink jet head, and may be configured to apply the treatment liquid to the surface of the paper 14 by discharging droplets of the treatment liquid. Moreover, it can also be set as the structure comprised by spraying and spraying a process liquid on the surface of the paper 14. FIG.

  The treatment liquid applied to the paper 14 is applied with a liquid having a function of aggregating the color material in the ink by reacting with the ink applied by the recording unit 40. When such a treatment liquid is applied in advance and ink droplets are ejected onto the paper 14, the ink droplets are aggregated immediately after landing, and even if the ink droplets land next to the ink droplets, It is possible to prevent material mixing.

  The treatment liquid application unit 30 is configured as described above. The sheet 14 transferred from the transfer drum 32 to the processing liquid drum 34 is applied with a processing liquid on the surface from the processing liquid applying device 36 in the process of being rotated and conveyed by the processing liquid drum 34. The sheet 14 to which the processing liquid is applied is transferred from the processing liquid drum 34 to the transfer drum 42, and transferred from the transfer drum 42 to the pressure drum 44 of the recording unit 40.

<Recording section>
The recording unit 40 forms C, M, Y, and K ink droplets on the surface of the paper 14 to form a color image on the surface of the paper 14. The recording unit 40 includes an impression cylinder (recording drum) 44 that conveys the paper 14 and inkjet heads 46C, 46M, 46Y, and 46K that eject ink droplets of C, M, Y, and K colors onto the paper 14. Configured.

  The recording drum 44 receives the sheet 14 from the transfer drum 42 (holds and receives the leading end of the sheet 14 with the gripper G), wraps around the circumferential surface, and rotates and conveys the sheet 14. At this time, the recording drum 44 receives the paper 14 from the transfer cylinder 42 with the surface of the paper 14 facing outside, and rotates and conveys the paper 14.

  When the transfer drum 42 receives the paper 14 from the processing liquid drum 34 of the processing liquid application unit 30, the transfer drum 42 has the surface (back surface) opposite to the image recording surface (front surface) outside and the paper from the processing liquid drum 34. 14 is received and the paper 14 is rotated and conveyed.

  The four inkjet heads 46C, 46M, 46Y, and 46K are arranged around the recording drum 44 at a constant interval, and discharge ink droplets of the corresponding colors toward the recording drum 44, respectively. The inkjet heads 46C, 46M, 46Y, and 46K are constituted by line heads corresponding to the paper width, and the surface (nozzle surface) facing the recording drum 44 is along a direction orthogonal to the conveyance direction of the paper 14. Thus, a nozzle row having a length corresponding to the paper width is formed.

  The recording unit 40 is configured as described above. The sheet 14 transferred from the processing liquid drum 34 to the recording drum 44 via the transfer drum 42 passes under the inkjet heads 46C, 46M, 46Y, 46K in the process of being rotated and conveyed by the recording drum 44, During the passage, ink droplets of each color of C, M, Y, and K are ejected from the inkjet heads 46C, 46M, 46Y, and 46K onto the surface, and a color image is recorded on the surface.

  At this time, since the processing liquid for aggregating the color material in the ink is applied to the paper 14 in advance, a high-quality image can be recorded without causing color material mixing or the like.

  Here, in the image portion, the water in the water-based ink is absorbed by the fibers in the paper 14, and the paper 14 is stretched. On the other hand, in the non-image area, the paper 14 does not absorb moisture, so that no elongation occurs. As described above, a difference occurs in the amount of elongation between the image portion and the non-image portion, and the amount of elongation of the paper becomes non-uniform, thereby causing unevenness called “cuckling”.

  The paper 14 on which the ink droplets of the respective ink colors C, M, Y, and K are ejected from the inkjet heads 46C, 46M, 46Y, and 46K and the image is recorded on the surface is received by the transfer drum 52 from the recording drum 44. Then, it is transferred from the transfer drum 52 to the pressure drum 54 of the drying unit 50.

  As described above, the ink jet recording apparatus 10 of the present embodiment performs image recording using water-based ink (ink containing at least water and a color material). Accordingly, each ink-jet head 46C, 46M, 46Y, 46K discharges the corresponding ink color water-based ink.

  In the ink jet recording apparatus 10 of the present embodiment, water-based ink in which a thermoplastic resin is dispersed in the ink is used. Thus, when the paper 14 is heated and pressurized by the subsequent heating and pressing unit 70, a film (resin film) can be formed by the thermoplastic resin contained in the ink, and the fastness of the image is improved. Can do.

  In this embodiment, the case where an image is recorded using four CMYK inks is described as an example. However, the combination of ink colors and the number of colors is not limited to this, and light ink is used as necessary. , Dark ink, special color ink, etc. may be added. For example, an ink jet head that discharges light ink such as light cyan and light magenta may be added. Also, the arrangement order of the color heads is not particularly limited.

<Dry section>
The drying unit 50 dries the paper 14 on which an image is recorded. The drying unit 50 includes a pressure drum (drying drum) 54 that transports the paper 14 and a drying device 56 that performs a drying process on the paper 14 transported by the drying drum 54.

  The drying drum 54 receives the paper 14 from the transfer drum 52 (holds and receives the front end of the paper 14 with the gripper G), wraps around the peripheral surface, and rotates and conveys the paper 14. At this time, the drying drum 54 receives the paper 14 from the transfer cylinder 52 with the surface of the paper 14 facing outward, and rotates and conveys the paper 14.

  The drying device 56 performs a process of evaporating moisture present on the paper. That is, when ink is ejected onto the paper 14 by the recording unit 40, the liquid component of the ink and the liquid component of the processing liquid separated by the aggregation reaction between the processing liquid and the ink remain on the paper. Then, a process for removing the liquid component is performed. The drying device 56 evaporates liquid components present on the paper by blowing warm air toward the paper 14 conveyed by the drying drum 54.

  The drying unit 50 is configured as described above. The paper 14 delivered from the recording drum 44 to the drying drum 54 via the transfer drum 52 is dried by blowing warm air from the drying device 56 in the course of conveyance by the drying drum 54. The sheet 14 that has passed through the drying device 56 is transferred from the drying drum 54 to the transfer drum 62 and conveyed to the humidifying unit 60.

<Humidification part>
The humidifying unit 60 humidifies the back surface of the paper 14 by applying humidified air to the back surface of the dried paper 14. The humidifying unit 60 includes a humidifying device 64 that injects humidified air toward the transfer drum 62.

  As shown in FIG. 2, the humidifier 64 blows humidified air from the outlet 66 provided facing the transfer drum 62 toward the peripheral surface of the transfer drum 62. The ejection port 66 is formed corresponding to the sheet width and is provided close to the peripheral surface of the transfer drum 62.

  When the paper 14 rotated and conveyed by the transfer drum 62 passes through the ejection port 66 of the humidifying device 64, the back surface is humidified by applying the humid air blown from the ejection port 66 to the rear surface.

  Here, the liquid constituting the humidified air, that is, the liquid used for humidifying the paper 14 is preferably water in consideration of handling and the like.

  Further, the liquid used for humidifying the paper 14 may contain a surfactant in order to promote the wetting and spreading of the liquid. Furthermore, in order to prevent generation | occurrence | production of mold | fungi etc., you may contain a preservative.

  The liquid used for humidifying the paper 14 may be a liquid other than water. However, if a liquid containing a water-soluble high-boiling solvent is used, the high-boiling solvent remains on the back surface side, and the water absorption property is increased. This causes a problem such as a decrease in drying of the image area during backside printing, and therefore it is preferable to use a liquid that does not contain a water-soluble high-boiling solvent as the liquid used for humidifying the paper 14.

  The humidifying unit 60 is configured as described above. The sheet 14 transferred from the drying drum 54 of the drying unit 50 to the transfer drum 62 is humidified by the humidified air blown from the humidifier 64 on the back surface in the process of being conveyed by the transfer drum 62.

  When the transfer drum 62 receives the paper 14 from the drying drum 54, the transfer drum 62 receives the paper 14 with the back surface outside. Accordingly, the paper 14 is conveyed with the back surface thereof directed to the humidifier 64. Therefore, by passing through the humidifier 64, humidified air is blown onto the back surface thereof.

  The sheet 14 that has passed through the humidifying device 64 is transferred from the transfer drum 62 to the pressure drum 74 of the heating and pressurizing unit 70.

<Heating and pressing part>
The heating and pressing unit 70 heats and presses a heat roller against the surface of the paper 14 whose back surface is humidified. The heating and pressing unit 70 includes a pressure drum (heating and pressing drum) 74 that conveys the paper 14 and a heat roller 76 that performs a heating and pressing process on the paper 14 that is conveyed by the heating and pressing drum 74. Has been.

  The heat and pressure drum 74 receives the paper 14 from the transfer drum 62 (holds and receives the leading edge of the paper 14 with the gripper G), wraps around the peripheral surface, and rotates and conveys the paper 14. At this time, the heat and pressure drum 74 receives the paper 14 from the transfer cylinder 62 with the surface of the paper 14 facing outside, and rotates and conveys the paper 14.

  The heat roller 76 heats and pressurizes the ink dried by the drying unit 50, thereby welding the thermoplastic resin dispersed in the ink to form a film of the ink. At the same time, the cockle generated on the paper 14 is corrected. The heat roller 76 is formed corresponding to the sheet width, and is pressed against the peripheral surface of the heat and pressure drum 74 with a predetermined pressing force. The heat roller 76 has a built-in heat source (for example, a halogen lamp), and is heated to a predetermined temperature by the heat source.

  Since the heat roller 76 is heated by a built-in heat source, the heat roller 76 is preferably formed of a metal pipe such as aluminum having good thermal conductivity.

  In addition, since the heat roller 76 is pressed and brought into contact with the image recording surface of the paper 14, the surface thereof is preferably coated with Teflon (registered trademark) or the like.

  The heating and pressing unit 70 is configured as described above. The sheet 14 transferred from the transfer drum 62 to the heating / pressurizing drum 74 is heated and pressed by the heat roller 76 being pressed against the surface in the process of being conveyed by the heating / pressurizing drum 74. As a result, the thermoplastic resin dispersed in the ink is welded to form a film of the ink. At the same time, the cockle generated on the paper 14 is corrected. At this time, in the ink jet recording apparatus 10 of the present embodiment, since the paper 14 is heated and pressurized after the humidification unit 60 humidifies the paper 14, the heat and pressure are applied while the rigidity of the paper 14 is reduced. And can correct the cockle well. Further, since the back surface of the paper 14 is humidified, drying of the ink on the front surface is not hindered. Thereby, generation | occurrence | production of roller offset and stacker blocking can also be prevented.

  The sheet 14 heated and pressed by the heat roller 76 is transferred from the heating and pressing drum 74 to the collecting unit 80.

<Recovery Department>
The collection unit 80 collects the paper 14 that has undergone a series of image recording processes in the stacker 82. The collection unit 80 includes a conveyor 84 that conveys the paper 14 to the stacker 82. The sheet 14 heated and pressed by the heating and pressing unit 70 is transferred from the heating and pressing drum 74 to the conveyor 84. Then, the conveyor 84 conveys the stacker 82 to the installation position. The stacker 82 is set at a predetermined collection position, and the paper 14 conveyed by the conveyor 84 is discharged into the stacker 82. The sheets 14 discharged into the stacker 82 are sequentially stacked and collected in the stacker.

<Image recording operation>
Next, an image recording operation by the inkjet recording apparatus 10 of the present embodiment configured as described above will be described.

  In the inkjet recording apparatus 10 of the present embodiment, the paper 14 is continuously fed from the paper feed unit 20 and images are continuously recorded.

  The paper 14 fed from the paper feeding device 22 is delivered to the transfer cylinder 32 via the paper feed tray 24. Then, it is transferred from the transfer drum 32 to the treatment liquid drum 34 of the treatment liquid application unit 30, and is rotated and conveyed by the treatment liquid drum 34 through the treatment liquid application unit 30. And in the conveyance process, a process liquid is provided to the surface from the process liquid application apparatus 36. FIG.

  The sheet 14 to which the processing liquid is applied is transferred from the processing liquid drum 34 to the transfer cylinder 42. Then, the recording drum 44 is transferred from the transfer drum 42 to the recording drum 44 of the recording unit 40, and is rotated and conveyed by the recording drum 44. In the transport process, ink droplets of water-based inks of C, M, Y, and K are ejected from the inkjet heads 46C, 46M, 46Y, and 46K onto the surface, and a color image is recorded on the surface. At this time, since the processing liquid for aggregating the color material in the ink is applied to the paper 14 in advance, a high-quality image can be recorded without causing color material mixing or the like.

  The paper 14 on which the image is recorded is transferred from the recording drum 44 to the transfer cylinder 52. Then, it is transferred from the transfer drum 52 to the drying drum 54 of the drying unit 50, and is rotated and conveyed by the drying drum 54 through the drying unit 50. Then, warm air is blown from the drying device 56 during the conveyance process, and the ink deposited on the surface is dried.

  The paper 14 on which the ink on the surface has been dried is transferred from the drying drum 54 to the transfer drum 62, and is rotated and conveyed by the transfer drum 62 through the humidifying unit 60. And the humidified air spouted from the humidifier 64 in the conveyance process is applied to the back surface, and the back surface is humidified.

  The sheet 14 whose back surface is humidified is transferred from the transfer drum 62 to the heating and pressing drum 74 of the heating and pressing unit 70, and is rotated and conveyed by the heating and pressing unit 70 by the heating and pressing drum 74. Then, the heat roller 76 is pressed and abutted on the surface during the conveyance process, and is heated and pressurized. As a result, the thermoplastic resin dispersed in the ink is welded to form a film of the ink. At the same time, the cockle generated on the paper 14 is corrected.

  The sheet 14 heated and pressed by the heat roller 76 is transferred from the heating and pressing drum 74 to the conveyor 84. Then, it is conveyed to the stacker 82 by the conveyor 84 and discharged to the stacker 82.

  The sheets 14 discharged to the stacker 82 are sequentially stacked and collected in the stacker.

  As described above, in the ink jet recording apparatus 10 of the present embodiment, an image is recorded through the process of applying the treatment liquid → applying the water-based ink → drying → humidifying → heating and pressing.

  In addition, by humidifying the paper 14 on which the water-based ink has been applied and dried in this manner before being heated and pressurized, the paper 14 can be heated and pressurized in a state where the rigidity of the paper 14 is reduced, and the cockle is improved. It can be corrected.

  In addition, since the back surface of the paper 14 is humidified during this humidification, drying of the ink on the front surface is not hindered. As a result, even when the paper 14 is heated and pressed from the front side by the heat roller 76, no roller offset occurs in the heat roller 76. Further, even if the collection unit 80 stacks and collects the sheets 14, stacker blocking does not occur.

  Note that if the amount of water supplied during humidification is too small, the sheet 14 cannot sufficiently reduce the rigidity, and the correction of the cockle becomes insufficient. On the other hand, if the amount of moisture supplied during humidification is too large, even if it passes through the heating and pressurizing unit 70, drying becomes insufficient and stacker blocking occurs in the collecting unit 80. Therefore, in order to perform higher quality image recording, it is preferable to set the amount of water supplied during humidification to an appropriate value.

  If the pressing force (nip pressure) of the heat roller 76 that performs heating and pressurization is too low, the pressure is insufficient and the cockle cannot be corrected well. Conversely, when the pressing force is too high, the pressure is too strong and roller offset occurs. On the other hand, if the temperature is too low, the rigidity of the paper 14 is not sufficiently lowered, and the cockle cannot be corrected well. Conversely, if the temperature is too high, the image area will be too soft and roller offset will occur. Therefore, in order to perform higher quality image recording, it is preferable to set the pressing force and temperature to appropriate values for the heat roller 76 as well.

  Therefore, an experiment was conducted to check the occurrence of cockle, roller offset and stacker blocking by changing the amount of moisture supplied during humidification, the pressing force of Herora, and the temperature of the heat roller. FIG. 3 is a table showing the experimental results. In the table, ◯ indicates good, Δ is generated but within the allowable range, and x indicates outside the allowable range.

As shown in the table, it is preferable to set the amount of water supplied during humidification within a range of 0.1 [g / m ² ] to 1.0 [g / m ² ]. This is because if it is less than 0.1 [g / m ² ], the rigidity of the paper 14 cannot be sufficiently lowered and the cockle cannot be corrected well. On the other hand, if it exceeds 1.0 [g / m ² ], even if it passes through the heating and pressurizing unit 70, drying becomes insufficient, and stacker blocking occurs in the collecting unit 80.

  The pressing force (nip pressure) of the heat roller 76 is preferably set within a range of 0.05 [MPa] to 0.5 [MPa]. This is because if the pressure is less than 0.05 [MPa], the pressure is insufficient and the cockle cannot be corrected well. On the other hand, if it exceeds 0.5 [MPa], the pressure is too strong and roller offset occurs.

  The temperature of the heat roller 76 is preferably set within a range of 40 [° C.] to 80 [° C.]. If it is less than 40 [° C.], the temperature is too low, the rigidity of the paper 14 is insufficiently lowered, and the cockle cannot be corrected well. On the other hand, if the temperature exceeds 80 [° C.], the image portion is too soft and roller offset occurs.

In this way, humidification is performed by setting the amount of supplied water within a range of 0.1 [g / m ² ] to 1.0 [g / m ₂ ], and heating and pressing are performed by pressing the heat roller 76. Is preferably set within a range of 0.05 [MPa] to 0.5 [MPa] and a temperature within a range of 40 [° C.] to 80 [° C.]. Thereby, it is possible to correct the cockle well without causing roller offset or stacker blocking.

[Second Embodiment]
FIG. 4 is an overall configuration diagram of the second embodiment of the ink jet recording apparatus according to the present invention.

  In the ink jet recording apparatus 100 of the present embodiment, the configuration of the humidifying unit 60 is different from the ink jet recording apparatus 10 of the first embodiment described above. Therefore, only the configuration of the humidifying unit 60 will be described here.

  In the inkjet recording apparatus 10 of the first embodiment described above, the back surface of the paper 14 is humidified by the humidifier 64. In the inkjet recording apparatus 10 of the present embodiment, the back surface of the paper 14 is humidified using the air discharged from the drying unit 50. That is, the humid air discharged from the drying unit 50 is guided to the humidification unit 60, and the humid air is blown onto the back surface of the paper 14 that is rotated and conveyed by the transfer drum 62, so that the back surface of the paper 14 is humidified.

  As shown in FIG. 4, the humidifying mechanism 110 according to the present embodiment includes a blower head 112 that blows wet air discharged from the drying unit 50 onto the back surface of the paper 14 that is rotated and conveyed by the transfer drum 62, and a drying unit 50. The air chamber 114 that collects the exhausted wet air, the air duct 116 that sends the humid air of the drying unit 50 collected in the air chamber 114 to the blow head 112, and the drying unit 50 that collects the air in the air chamber 114. An air supply fan 118 that supplies humid air to the air blowing head 112 via the air duct 116 is configured.

  The blower head 112 is formed corresponding to the paper width, and has an air ejection opening corresponding to the paper width. The air outlet is provided close to the peripheral surface of the transfer drum 62. When the paper 14 rotated and conveyed by the transfer cylinder 62 passes through the ejection port of the blower head 112, the back surface is humidified by applying wet air ejected from the ejection port to the rear surface.

  The air chamber 114 is formed in a box shape with an open top, and is installed so as to cover the lower part of the drying drum 54 of the drying unit 50.

  The air duct 116 has one end connected to the air blowing head 112 and the other end connected to the air chamber 114, and guides the humid air collected in the air chamber 114 to the air blowing head 112.

  The air supply fan 118 is installed in the middle of the air duct 116, and supplies the humid air collected by the air chamber 114 to the blow head 112.

  The humidifying mechanism 110 is configured as described above. According to the humidifying mechanism 110, when the air supply fan 118 is rotationally driven, the humid air discharged from the drying unit 50 is collected by the air chamber 114 and is supplied to the air blowing head 112 through the air duct 116. The air is then ejected from the air ejection port of the blower head 112 toward the peripheral surface of the transfer drum 62. As a result, when the paper 14 is conveyed by the transfer drum 62, the humid air blown from the air outlet of the blowing head 112 is applied to the back surface of the paper 14, and the back surface of the paper 14 is humidified.

  As described above, in the ink jet recording apparatus 100 of the present embodiment, the paper 14 is humidified using the humid air generated during the drying in the drying unit 50. Thereby, the apparatus can be operated efficiently.

Also in the ink jet recording apparatus 100 of the present embodiment, the amount of water supplied during humidification is preferably 0.1 [g / m ² ] to 1.0 [g / m ₂ ].

  The heating and pressing are preferably performed by setting the pressing force of the heat roller 76 within the range of 0.05 [MPa] to 0.5 [MPa] and the temperature within the range of 40 [° C.] to 80 [° C.]. .

  In the ink jet recording apparatus 100 of the present embodiment, the humidifier 64 may be incorporated and used together with the humidifier 64 as necessary to humidify the paper.

[Other Embodiments]
In the first embodiment, the humidified air generated by the humidifier 64 is blown against the back surface of the paper 14 to humidify the back surface of the paper 14, but the configuration for humidifying the back surface of the paper 14 is as follows. In addition to this, for example, a liquid (for example, water) may be sprayed with a sprayer to humidify the back surface of the paper 14. Moreover, it is good also as a structure which sprays a liquid from a spray and humidifies the back surface of the paper 14. FIG.

  In the above embodiment, the case where an image is recorded on only one side of the paper 14 has been described. However, when recording an image on both sides of the paper 14, the front and back of the paper 14 are changed and the image is recorded again. . That is, the paper 14 collected in the stacker 82 is taken out, set up again on the paper feeding device 22 with the front and back sides changed, the ink jet recording device is operated again, and recording on the back side is performed. As a result, images can be recorded on both sides of the paper 14. In this case, in the ink jet recording apparatus of the present embodiment, the back side image recording is performed in a state in which the cockle is corrected well, so that a high-quality image can be recorded also on the back side. Further, even when a predetermined number of sheets are stacked and collected, they can be collected without causing stacker blocking.

  Further, after the recording on the front side is completed, the recording on the back side may be continuously performed. That is, it is configured not to collect the heated and pressurized paper but to continuously record on the back side as it is. Specifically, the first recording unit that records ink by ejecting ink onto the front surface (first surface) of the paper, and the back surface (second second) of the paper on which the image is recorded on the front surface (first surface). A first humidifying unit that humidifies the surface), and a first heating and pressurizing unit that heats and presses the heat roller against the front surface (first surface) of the paper whose back surface (second surface) is humidified. A front and back reversing unit for reversing the front and back of the heated and pressurized paper, a second recording unit for recording an image by ejecting ink onto the back (second side) of the paper whose front and back are reversed, and the back A second humidifying unit that humidifies the front surface (first surface) of the paper on which an image is recorded on the (second surface), and a heat roller on the back surface (second surface) of the paper whose surface (first surface) is humidified. It is also possible to provide a double-sided ink jet recording apparatus provided with a second heating and pressing unit that presses and abuts to press and heat.

  Also in this case, a drying unit can be installed in front of each humidifying unit, and each humidifying unit can be configured to supply humidified air discharged from each drying unit to the paper for humidification.

  In the above-described embodiment, the case where an image is recorded using an aqueous ink containing a thermoplastic resin has been described as an example. However, an aqueous actinic ray curable ink (for example, an aqueous UV ink) is also used. An image can also be recorded. In this case, an actinic ray irradiation device is installed in the heating and pressing unit.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 14 ... Paper, 20 ... Paper feeding part, 30 ... Processing liquid application part, 32 ... Transfer cylinder, 34 ... Impression cylinder (processing liquid drum), 36 ... Processing liquid application apparatus, 40 ... Recording part, 42 ... transfer cylinder, 44 ... impression cylinder (recording drum), 46C, 46M, 46Y, 46K ... inkjet head, 50 ... drying section, 52 ... transfer cylinder, 54 ... impression cylinder (dry drum), 56 ... drying device, 60 ... Humidifying section, 62 ... Transfer cylinder, 64 ... Humidifying device, 70 ... Heating and pressing section, 72 ... Transfer cylinder, 74 ... Pressure cylinder (heating and pressing drum), 76 ... Heat roller, 80 ... Collection section, 82 ... Stacker , 84 ... Conveyor, 100 ... Inkjet recording device, 110 ... Humidification mechanism, 112 ... Blower head, 114 ... Air chamber, 116 ... Air duct, 118 ... Air supply fan

Claims (13)

A paper feeding unit for continuously feeding sheets of paper,
A recording unit for recording an image by ejecting water-based ink onto the surface of a sheet fed from the sheet feeding unit with an inkjet head;
A humidifying unit for humidifying the back side of the paper on which the image is recorded on the front side in the recording unit;
A heating and pressing unit that presses and heats a heat roller against the surface of the paper whose back surface is humidified by the humidifying unit; and
A collecting unit that stacks and collects the sheets heated and pressed by the heating and pressing unit;
An ink jet recording apparatus comprising: A first recording unit that records an image by ejecting water-based ink onto the surface of a sheet of paper with an inkjet head;
A first humidifying unit for humidifying the back surface of the paper on which an image is recorded;
A first heating and pressing unit that presses and heats a heat roller against the surface of the paper whose back surface is humidified;
A front / back reversing section that reverses the front / back of the paper
A second recording unit that records an image by ejecting water-based ink onto the reverse side of the paper that has been reversed with an inkjet head; and
A second humidifying unit for humidifying the front surface of the paper on which an image is recorded on the back surface;
A second heat and pressure unit that heats and presses a heat roller against the back surface of the paper whose surface is humidified;
An ink jet recording apparatus comprising: 3. The ink jet recording according to claim 1, wherein an amount of water supplied to the back surface of the paper by the humidifying unit is 0.1 [g / m ² ] to 1.0 [g / m ² ]. apparatus.   The inkjet recording apparatus according to any one of claims 1 to 3, wherein the pressing force of the heat roller is 0.05 [MPa] to 0.5 [MPa].   5. The inkjet recording apparatus according to claim 1, wherein a temperature of the heat roller is 40 [° C.] to 80 [° C.].   The ink jet recording apparatus according to claim 1, wherein the liquid that humidifies the back surface of the paper in the humidifying unit is water.   The ink jet recording apparatus according to claim 1, wherein the liquid that humidifies the back surface of the paper in the humidifying unit contains a surfactant and / or a preservative.   The humidifying unit further includes a drying unit that dries the water-based ink ejected on the surface of the paper by the recording unit before humidifying by the humidifying unit, and the humidifying unit removes the humid air discharged from the drying unit of the paper. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is applied to the back surface to humidify the back surface of the paper.   The inkjet recording apparatus according to claim 1, wherein the water-soluble ink contains a thermoplastic resin.   The inkjet recording apparatus according to any one of claims 1 to 8, wherein the water-soluble ink is an actinic ray curable ink. A first recording step of recording an image by ejecting water-based ink onto the surface of a sheet of paper with an inkjet head; and
A first humidifying step of humidifying the back surface of the paper having an image recorded on the front surface;
A first heating and pressurizing step in which a heat roller is pressed against and brought into contact with the surface of the paper whose back surface is humidified;
A second recording step of recording an image by ejecting water-based ink with an inkjet head on the back surface of the heated and pressurized paper;
A second humidifying step of humidifying the front surface of the paper on which an image is recorded on the back surface;
A second heating and pressing step in which a heat roller is pressed against and brought into contact with the back surface of the paper whose surface is humidified,
An ink jet recording method comprising:   12. The inkjet recording according to claim 11, further comprising a collecting step of collecting a predetermined number of the sheets heated and pressed in the first heating and pressing step and collecting them before the second recording step. Method. The amount of water supplied to the back surface of the paper in the first humidifying step and the second humidifying step is 0.1 [g / m ² ] to 1.0 [g / m ² ], and the first heating The pressing force of the heat roller in the pressing step and the second heating and pressing step is 0.05 [MPa] to 0.5 [MPa], and the temperature is 40 [° C.] to 80 [° C.] The inkjet recording method according to claim 11 or 12.

Images