JP2010173149A - Image forming method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an apparatus capable of pivoting and conveying a form under a stable condition and forming an image. <P>SOLUTION: In the image forming method, the image is formed by hitting ink by an inkjet head on the form sucked and conveyed by an impression cylinder. In the image forming method in which the ink is hit by applying a treating liquid having an ink agglomerating function on a printing face of the form in advance, when the treating liquid is applied on the form, the treating liquid with a larger amount of the liquid than the amount of the liquid of the treating liquid applied on an image forming region is applied to the margin region on the back end of the form. The rigidity of the form is decreased thereby and the air tightness is improved, and when the form is sucked and conveyed by the impression cylinder, the form can be stably conveyed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method and apparatus, and more particularly to an image forming method and apparatus for forming an image by ejecting ink onto a sheet of paper that is rotated and conveyed by a rotating conveyance body with an inkjet head.

  In recent years, there has been an increasing demand for small copies in the printing industry. However, the offset printing machine that is currently used in the printing field has a drawback in that if a small number of copies are printed, a plate must be prepared. Therefore, an inkjet printer has attracted attention as a method capable of printing without creating such a plate.

  By the way, in printing, printing paper such as coated paper is generally used, and it is essential that these papers can be used even when printing is performed by an ink jet method. However, there is a problem that feathering, bleeding, and the like occur when ink is directly ejected onto such a sheet by an ink jet method. For this reason, conventionally, when printing is performed on a printing paper such as a coated paper by an ink jet method, a processing liquid having a function of aggregating ink is applied to the paper in advance (for example, Patent Document 1). 2).

  In addition, as can be seen in an offset printing machine, a method of rotating and conveying a sheet with an impression cylinder is often used in printing. However, since the conveyance by the impression cylinder usually conveys the paper by gripping only the leading edge of the paper, there is a problem that the rear end portion of the paper tends to float from the impression cylinder. When the sheet is floated by an ink jet printer, not only printing failure occurs but also the sheet comes into contact with the head and causes a failure. In addition, in an apparatus that performs drying and fixing in a subsequent process, there is a problem that a drying defect and a fixing defect easily occur due to the sheet floating at the rear end.

  As a technique for preventing such paper floating and stably transporting the paper, Patent Document 3 discloses that a suction hole is formed in the table to suck and hold the paper and strongly suck the peripheral portion of the paper. Techniques have been proposed to prevent paper from floating. Japanese Patent Application Laid-Open No. 2004-228620 proposes that the suction force is varied in accordance with the type and thickness of the paper in the method of sucking and holding the paper. Japanese Patent Application Laid-Open No. 2004-228561 proposes a method of carrying and rotating a paper while holding the paper on a drum, and transporting the paper by holding the rear end portion of the paper through a pin.

Japanese Patent Laid-Open No. 2001-353861 JP 2000-238258 A JP 2007-144848 A JP 2001-239713 A Japanese Patent Publication No. 55-13912

  The method of Patent Document 3 increases the suction force at the periphery of the sheet, so that a certain level of adsorption stabilization is possible. However, when the sheet has high rigidity, such as thick paper, or adsorbs paper that has been undulated by moisture absorption. Has the disadvantage of being difficult.

  In addition, the method of Patent Document 4 controls the suction force according to the type and thickness of the paper, so that a certain level of holding stability can be ensured. In particular, there is a drawback that the rear end portion is liable to be lifted easily in the impression cylinder transport of cardboard.

  In addition, the method of Patent Document 5 can be expected to have a certain effect in preventing the trailing edge of the sheet from being lifted during conveyance of the impression cylinder. However, a rigid sheet such as a thick sheet is difficult to penetrate and has a defect such as a burr caused by the penetration. There is a drawback that it is easy to occur.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image forming method and apparatus capable of forming an image by rotating and conveying a sheet in a stable state.

  In order to achieve the above object, the invention according to claim 1 applies at least a predetermined processing liquid to the image forming area with respect to a recording medium in which the image forming area is set with a margin at the rear end in the transport direction. After applying the liquid in a predetermined amount, the recording medium is sucked and held on the peripheral surface of the rotating carrier while the tip of the recording medium is held by the gripping means, and the recording is carried by the rotation. In the image forming method of forming an image by ejecting ink onto the image forming area of the medium with an inkjet head, when applying the processing liquid to the recording medium, the amount of the processing liquid applied to the image forming area An image forming method is characterized in that a treatment liquid having a larger liquid amount is applied to a blank area at the rear end of the recording medium.

  According to the present invention, when the processing liquid is applied to the recording medium, the processing liquid having a larger liquid volume than the processing liquid applied to the image forming area is applied to the blank area at the rear end in the conveyance direction of the recording medium. , The rigidity of the region is reduced, and the airtightness is improved. As a result, it is possible to prevent the trailing edge of the recording medium from being lifted during rotational conveyance, and the recording medium can be stably conveyed. In addition, when the recording medium is sucked with a negative pressure on the peripheral surface of the rotating conveyance body, the airtightness is improved and the suction is further stabilized. For example, when the recording medium is coated paper, the amount of the treatment liquid to be applied to the blank area is applied with a thickness equal to or greater than the thickness of the coating layer.

  According to a second aspect of the present invention, in order to achieve the above object, the amount of the treatment liquid applied to the blank area at the rear end of the recording medium can be varied according to the thickness or bending rigidity of the recording medium. An image forming method according to claim 1 is provided.

  According to the present invention, the amount of the treatment liquid applied to the blank area at the rear end in the conveyance direction of the recording medium can be varied according to the thickness or bending rigidity of the recording medium. As a result, the treatment liquid can be applied in an appropriate amount for each recording medium, and appropriate bending strength and airtightness can be ensured. Moreover, since excessive provision can be prevented by this, generation | occurrence | production of cockling (rippling), back surface contamination, etc. can also be suppressed. As a variable example, for example, the treatment liquid is applied at a thickness that is ½ of the thickness of the recording medium.

  According to a third aspect of the present invention, in order to achieve the above object, the treatment liquid applied to the blank area at the rear end in the conveyance direction of the recording medium is in a line shape parallel to a direction orthogonal to the conveyance direction of the recording medium. 3. The image forming method according to claim 1, wherein the amount of application is reduced at both ends in the conveyance direction.

  According to the present invention, the treatment liquid to be applied to the blank area at the rear end in the conveyance direction of the recording medium is applied in a line shape parallel to the direction orthogonal to the conveyance direction of the recording medium, and at both ends in the conveyance direction. The applied amount is suppressed. Thereby, wetting and spreading of the treatment liquid can be suppressed, and cockling of the recording medium, contamination of the apparatus, and back flow of the treatment liquid can be prevented.

  In order to achieve the above object, the image forming area is set by leaving a margin on the leading edge in the transport direction and / or on both sides to achieve the above object, and a blank area at the leading edge of the recording medium, The processing liquid having a larger liquid volume than the liquid volume of the processing liquid to be applied to the image forming area is also applied to the blank areas on both sides. The described image forming method is provided.

  According to the present invention, the image forming area is set with a margin on the leading edge in the transport direction and / or on both sides, and the margin area on the leading edge of the recording medium and / or the margin area on both sides is also set. A treatment liquid having a larger amount than the treatment liquid to be applied to the image forming area is applied. Thereby, more stable conveyance is enabled. That is, by applying the treatment liquid having a larger amount than the treatment liquid to be applied to the image forming area to the blank area at the front end of the recording medium, the adsorption of the recording medium by the gripping unit by the gripping unit is stabilized. In addition, by applying processing liquid with a larger amount of processing liquid than the amount of processing liquid applied to the image forming area to the margin areas on both sides, the rigidity in the transport direction is reduced and the airtightness is improved, making it more stable. It is possible to adsorb the recorded medium.

  In order to achieve the above object, the invention according to claim 5 is characterized in that, when an image is formed by ejecting ink onto the image forming area with the inkjet head, ink is ejected onto the blank area. An image forming method according to any one of claims 1 to 4 is provided.

  According to the present invention, ink is also ejected into the blank area during image formation. Thereby, the evaporation of the treatment liquid can be compensated, the rigidity of the recording medium can be reduced, and the airtightness can be increased. Thus, the recording medium can be stably conveyed even when the recording medium is rotated and conveyed in the process after the image formation. For example, when the recording medium is rotated and conveyed after image formation and dried by the drying means, contact with the drying means can be prevented. Moreover, when heating a back surface, the heating can also be stabilized. Furthermore, since the ink agglomerates due to the reaction with the processing liquid, the liquid flow can be prevented and the contact with the rotating carrier is stable even when drying with strong drying air, so that the fixing property is stable. Can also be improved. Also, if the recording medium is dried while adsorbed, deformation such as cockling due to the processing liquid or ink can be further reduced. Furthermore, if ink is ejected onto the recording medium, it can be used as a purge operation, so that ink ejection can be stabilized.

  According to a sixth aspect of the invention, in order to achieve the above object, when the recording medium is rotated and conveyed by the rotating conveyance body, the conveyance area is rotated while holding a blank area at the rear end of the recording medium with a pin. An image forming method according to claim 1 is provided.

  According to the present invention, when the recording medium is rotated and conveyed, the blank area at the rear end in the conveying direction of the recording medium is held by the pin. By holding the blank area at the rear end in the conveyance direction of the recording medium with a pin, it is possible to reliably prevent the trailing end of the recording medium from floating. Further, even when the rear end portion of the recording medium is held with a pin as described above, the rigidity is lowered by the application of the treatment liquid, so even a highly rigid recording medium such as cardboard can be easily pinned. Therefore, burrs generated during penetration can be suppressed.

  According to a seventh aspect of the present invention, in order to achieve the above object, at least a predetermined processing liquid is applied to the image forming area with respect to a recording medium in which the image forming area is set with a margin at the rear end in the transport direction. After applying a predetermined amount of liquid, the recording medium is adsorbed and held on the peripheral surface of the rotating conveyance body while holding the blank area at the tip of the recording medium with the gripping means, and the rotating conveyance is performed. In the image forming apparatus for forming an image by ejecting ink onto the image forming area of the recording medium by an ink jet head, the processing liquid applying unit applies a predetermined processing liquid to at least the image forming area. The image forming is characterized in that the processing liquid having a liquid amount set larger than the liquid amount of the processing liquid to be applied to the image forming area is applied to the blank area at the rear end of the recording medium. Provide equipment That.

  According to the present invention, when the processing liquid is applied to the recording medium, the processing liquid having a larger liquid volume than the processing liquid applied to the image forming area is applied to the blank area at the rear end in the conveyance direction of the recording medium. , The rigidity of the region is reduced, and the airtightness is improved. As a result, it is possible to prevent the trailing edge of the recording medium from being lifted during rotational conveyance, and the recording medium can be stably conveyed. In addition, when the recording medium is sucked with a negative pressure on the peripheral surface of the rotating conveyance body, the airtightness is improved and the suction is further stabilized. For example, when the recording medium is coated paper, the amount of the treatment liquid to be applied to the blank area is applied with a thickness equal to or greater than the thickness of the coating layer.

  In order to achieve the above object, the invention according to claim 8 includes setting means for setting a liquid amount of a processing liquid to be applied to a blank area at the rear end in the conveyance direction of the recording medium, and the setting means includes the recording medium. 8. The image forming apparatus according to claim 7, wherein the amount of the processing liquid applied to the blank area at the rear end in the conveyance direction of the recording medium is set in a variable manner according to the thickness or bending rigidity of the medium. To do.

  According to the present invention, the amount of the treatment liquid applied to the blank area at the rear end in the conveyance direction of the recording medium can be varied according to the thickness or bending rigidity of the recording medium. As a result, the treatment liquid can be applied in an appropriate amount for each recording medium, and appropriate bending strength and airtightness can be ensured. Moreover, since excessive provision can be prevented by this, generation | occurrence | production of cockling, a back surface contamination, etc. can also be suppressed. As a variable example, for example, the treatment liquid is applied at a thickness that is ½ of the thickness of the recording medium.

  According to a ninth aspect of the present invention, in order to achieve the above object, the treatment liquid applying means is parallel to a direction perpendicular to the conveyance direction of the recording medium with respect to a blank area at the rear end in the conveyance direction of the recording medium. The image forming apparatus according to claim 7 or 8, wherein the processing liquid is applied in a line shape and the applied amount is reduced at both ends in the transport direction.

  According to the present invention, the treatment liquid to be applied to the blank area at the rear end in the conveyance direction of the recording medium is applied in a line shape parallel to the direction orthogonal to the conveyance direction of the recording medium, and at both ends in the conveyance direction. The applied amount is suppressed. Thereby, wetting and spreading of the treatment liquid can be suppressed, and cockling of the recording medium, contamination of the apparatus, and back flow of the treatment liquid can be prevented.

  According to a tenth aspect of the present invention, in order to achieve the above object, the image forming area is set with margins on the front end and / or both sides in the transport direction, and the processing liquid applying means is configured to record the recording liquid. The amount of processing liquid set larger than the amount of processing liquid applied to the image forming area is also applied to the blank area at the front end of the medium and / or the blank area on both sides. An image forming apparatus according to any one of Items 7-9 is provided.

  According to the present invention, the image forming area is set with a margin on the leading edge in the transport direction and / or on both sides, and the margin area on the leading edge of the recording medium and / or the margin area on both sides is also set. A treatment liquid having a larger amount than the treatment liquid to be applied to the image forming area is applied. Thereby, more stable conveyance is enabled. That is, by applying the treatment liquid having a larger amount than the treatment liquid to be applied to the image forming area to the blank area at the front end of the recording medium, the adsorption of the recording medium by the gripping unit by the gripping unit is stabilized. In addition, by applying processing liquid with a larger amount of processing liquid than the amount of processing liquid applied to the image forming area to the margin areas on both sides, the rigidity in the transport direction is reduced and the airtightness is improved, making it more stable. It is possible to adsorb the recorded medium.

  According to an eleventh aspect of the present invention, in order to achieve the above object, the ink jet head ejects ink onto the blank area when ejecting ink onto the image forming area to form an image. An image forming apparatus according to any one of claims 7 to 10 is provided.

  According to the present invention, ink is also ejected into the blank area during image formation. Thereby, the evaporation of the treatment liquid can be compensated, the rigidity of the recording medium can be reduced, and the airtightness can be increased. Thus, the recording medium can be stably conveyed even when the recording medium is rotated and conveyed in the process after the image formation. For example, when the recording medium is rotated and conveyed after image formation and dried by the drying means, contact with the drying means can be prevented. Moreover, when heating a back surface, the heating can also be stabilized. Furthermore, since the ink agglomerates due to the reaction with the processing liquid, the liquid flow can be prevented and the contact with the rotating carrier is stable even when drying with strong drying air, so that the fixing property is stable. Can also be improved. Also, if the recording medium is dried while adsorbed, deformation such as cockling due to the processing liquid or ink can be further reduced. Furthermore, if ink is ejected onto the recording medium, it can be used as a purge operation, so that ink ejection can be stabilized.

  According to a twelfth aspect of the present invention, in order to achieve the above object, the rotating carrier grips the blank area at the front end of the recording medium and rotates while holding the blank area at the rear end through a pin. The image forming apparatus according to claim 7, wherein the image forming apparatus is conveyed.

  According to the present invention, when the recording medium is rotated and conveyed, the blank area at the rear end in the conveying direction of the recording medium is held by the pin. By holding the blank area at the rear end in the conveyance direction of the recording medium with a pin, it is possible to reliably prevent the trailing end of the recording medium from floating. Further, even when the rear end portion of the recording medium is held with a pin as described above, the rigidity is lowered by the application of the treatment liquid, so even a highly rigid recording medium such as cardboard can be easily pinned. Therefore, burrs generated during penetration can be suppressed.

  According to the present invention, an image can be formed by rotating and conveying a sheet in a stable state.

1 is an overall configuration diagram showing an embodiment of an inkjet printer to which the present invention is applied. Side sectional view showing the schematic configuration of the impression cylinder Development view of the periphery of the impression cylinder Plane perspective view showing schematic structure of ink head Sectional drawing which follows the BB line of FIG. 1 is a block diagram showing a schematic configuration of a control system of an ink jet printing machine according to the present embodiment. The figure which shows the relationship between the application | coating area | region of a penetration inhibitor, the application | coating area | region of a process liquid, and an image formation area Diagram showing margin area The perspective view which shows another example of a process liquid provision apparatus Side surface sectional view showing a schematic configuration of an impression cylinder provided with a perforation holding mechanism

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

≪Device configuration≫
FIG. 1 is an overall configuration diagram showing an embodiment of an inkjet printer to which the present invention is applied.

  As shown in the figure, the ink jet printer 10 according to the present embodiment mainly feeds a sheet (recording medium) 14 in the form of a sheet, and is fed from the sheet feeder 22. A permeation inhibitor imparting section 24 that imparts a permeation inhibitor to the sheet 14, and a treatment liquid imparting section 26 that imparts a predetermined processing liquid on the paper 14 that has been impregnated with the permeation inhibitor in the permeation inhibitor imparting section 24. In addition, a drawing unit 28 that draws ink on the paper 14 to which the processing liquid has been applied by the processing liquid application unit 26 and draws an image, and water in the ink that has been applied to the paper 14 by the drawing unit 28 is evaporated. A drying unit 30 for drying, a fixing unit 32 for fixing the image after drying onto the paper 14, and a paper discharge unit 34 for discharging the paper 14 on which the image is fixed by the fixing unit 32 are configured.

<Paper Feeder>
The paper feed unit 22 that feeds the paper 14 mainly includes a paper feed tray 36 that guides the paper 14, an adhesive roller 37 that feeds the paper 14 along the paper feed tray 36, and an adhesive roller 37 on the paper feed tray 36. And a transfer cylinder 38 that receives the transferred paper 14 and transfers it to the impression cylinder 40 of the permeation suppression agent applying unit 24.

  The sheets 14 are stocked in a magazine (not shown) and are supplied one by one from the magazine to the sheet feed tray 36. The paper 14 supplied to the paper feed tray 36 is sent out toward the transfer drum 38 by the adhesive roller 37. The transfer drum 38 receives the paper 14 from the paper feed tray 36, rotates and conveys it to the pressure drum 40 of the permeation suppression agent applying unit 24.

  The type of the recording medium is not particularly limited, but here, 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 (such as a kaolin-containing material) that is applied to improve smoothness and ink absorbability. The paper is further divided into art paper, coated paper, and finely coated paper. Here, coated paper, particularly coated paper is used.

<Penetration inhibitor application part>
The permeation suppression agent applying unit 24 applies a permeation suppression agent that suppresses the penetration of water and a hydrophilic organic solvent contained in the treatment liquid and the ink into the paper 14 to the printing surface of the paper 14 and suppresses the permeation into the paper 14. Process.

  The permeation suppression agent applying unit 24 mainly includes a pressure drum 40 that rotates and conveys the paper 14, and a permeation inhibitor application device that applies a permeation suppression agent to the printing surface of the paper 14 that is rotated and conveyed by the pressure cylinder 40. 42, a sheet presser 44 that suppresses the sheet 14 that is rotated and conveyed by the impression cylinder 40 at a subsequent position of the permeation suppression agent application device 42, and a permeation suppression agent that is applied to the sheet 14 at a subsequent position of the sheet presser 44. And a permeation inhibitor drying unit 46.

  The impression cylinder 40 is formed in a drum shape, and is rotated by being driven by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the impression cylinder 40. The paper 14 is rotated and conveyed with its gripper gripped at the tip.

  The permeation suppression agent application device 42 applies a permeation suppression agent to the printing surface of the paper 14 by pressing an application roller 48 having a permeation suppression agent on the circumferential surface against the printing surface of the paper 14 being rotated and conveyed.

  The application roller 48 has a spiral groove formed on the peripheral surface (a so-called spiral roller), and is pressed against the paper 14 while being driven to rotate in a direction opposite to the rotation direction of the impression cylinder 40 by a motor (not shown). The permeation inhibitor is applied to the application roller 48 by a spray (not shown). The spray is configured so that a permeation inhibitor can be applied to the application roller 48 with an arbitrary application width. By adjusting the application width, the application width of the permeation inhibitor applied to the paper 14 is adjusted. Is done. Further, the spray is configured so that the permeation inhibitor can be applied to the application roller 48 at an arbitrary application amount. By adjusting this application amount, the application amount of the permeation inhibitor applied to the paper 14 is adjusted. Is adjusted.

  The permeation suppressor coating device 42 presses the application roller 48 against the printing surface of the paper 14 in accordance with the passage timing of the paper 14, thereby applying the permeation suppression agent to a predetermined region of the printing surface of the paper 14 with a predetermined thickness. Apply.

  The permeation suppression agent drying unit 46 blows hot air (for example, temperature: 50 to 130 ° C., wind speed: 5 to 50 m / s) onto the paper 14 that is rotated and conveyed by the impression cylinder 40, and is applied to the paper 14. Allow the inhibitor to dry.

  In addition, as a penetration inhibitor used in the present embodiment, a latex solution containing polymer particles such as LX-1 described in Table 1 below is preferably used.

  In the above [Table 1], “Tg” is the glass transition point of the polymer added in the liquid, “MFT” is the minimum film forming temperature of the polymer, and “Tm” is the polymer. Of the melting point.

  Of course, the penetration inhibitor is not limited to the latex solution, and for example, tabular grains (mica and the like), water repellent (fluorine coating agent) and the like can be applied.

  An example of adjusting the penetration inhibitor will be described in detail later.

<Treatment liquid application unit 26>
The treatment liquid application unit 26 applies a treatment liquid containing a component that aggregates or thickens the color material (pigment or dye) in the ink ejected by the drawing unit 28 onto the paper 14 on which the permeation inhibitor is applied. Give it again.

  The treatment liquid application unit 26 mainly receives the paper 14 from the impression cylinder 40 of the permeation suppression agent application unit 24 and rotates and conveys the paper 14, and the impression cylinder that receives and rotates the paper 14 from the transfer cylinder 85. 86, a processing liquid applying device 202 that applies a processing liquid to the printing surface of the paper 14 that is rotated and conveyed by the impression cylinder 86, and a processing liquid drying unit 204 that dries the paper 14 to which the processing liquid has been applied. ing.

  The transfer drum 85 is formed in a drum shape, and is driven to rotate by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the transfer drum 85. The paper 14 is rotated and conveyed with its gripper gripped at the tip. At this time, the paper 14 is conveyed in a non-contact state with the printing surface inside.

  The impression cylinder 86 is formed in a drum shape and is driven to rotate by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the impression cylinder 86, and the paper 14 is rotated and conveyed with the leading end held by the gripper.

  The treatment liquid applying device 202 is composed of a line-type inkjet head (so-called line head) corresponding to the width of the paper 14 to be printed, and a nozzle array provided on a surface (discharge surface) facing the impression cylinder 86. Then, a droplet of the treatment liquid is ejected from the substrate, and the treatment liquid is applied to the printing surface of the paper 14 that is rotated and conveyed to the impression cylinder 86.

  The treatment liquid applying apparatus 202 configured with such a line-type inkjet head controls the discharge timing of each nozzle in accordance with the conveyance speed of the sheet 14 that is rotated and conveyed by the impression cylinder 86, thereby The treatment liquid can be applied to the desired region. Further, by controlling the discharge amount, it is possible to control the amount of treatment liquid applied to each region.

  In the inkjet printer 10 according to the present embodiment, the processing liquid is uniformly applied at a constant liquid amount to at least the image forming area, and the amount of processing liquid applied to the image forming area in the trailing edge blank area of the paper 14 is determined. A treatment liquid with a larger liquid amount is applied. This is because the rigidity of the trailing edge of the sheet is lowered and the airtightness is increased by applying a treatment liquid having a larger amount than the amount of the treatment liquid applied to the image forming area to the trailing edge blank area of the sheet 14. Thus, when the paper 14 is rotated and conveyed by the next drawing unit 28, it is possible to effectively prevent the rear end portion of the paper 14 from floating. This point will be described in detail later.

  The treatment liquid drying unit 204 blows hot air (for example, temperature: 50 to 130 ° C., wind speed: 5 to 50 m / s) onto the paper 14 that is rotated and conveyed by the impression cylinder 86, and the treatment liquid applied to the paper 14. Dry.

  The treatment liquid used in the present embodiment is preferably an acidic liquid having an action of aggregating the color materials contained in the ink ejected from the respective ink heads 210K, 210C, 210M, and 210Y toward the paper 14 in the drawing unit 28. . Specifically, the treatment liquid described in Table 2 of the adjustment examples described later, and the treatment liquid to which an acid such as 2-pyrrolidone-5-carboxylic acid, phosphoric acid, succinic acid, or citric acid is added can be considered.

  In addition, a high-boiling-point solvent such as glycerin or a small amount of polymer particles such as LX-1 described in Table 1 or LX-2 described in Table 4 is added to suppress the penetration of the treatment liquid, thereby reducing the permeation suppression layer. It is also possible to make it unnecessary. For this reason, when the treatment liquid having such a penetration inhibiting effect is applied by the penetration inhibitor coating apparatus 42, the pressure drum 86 of the treatment liquid application unit 26, the treatment liquid application apparatus 202, the treatment liquid drying unit 204, and the like. Is no longer necessary.

  An example of adjusting the treatment liquid will be described in detail later.

<Drawing part>
The drawing unit 28 forms an image on the surface of the paper 14 by ejecting colored ink onto the surface of the paper 14 to which the treatment liquid is applied.

  The drawing unit 28 mainly receives the paper 14 from the pressure drum 86 of the treatment liquid application unit 26 and rotates and conveys the paper 14. The drawing unit 28 receives the paper 14 from the transfer drum 214 and rotates and conveys the paper 14. An ink head for ejecting ink droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y) onto the paper 14 that is rotated and conveyed by the impression cylinder 216. 210K, 210C, 210M, and 210Y.

  The transfer drum 214 is formed in a drum shape and is rotated by being driven by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the transfer drum 214. The paper 14 is rotated and conveyed with its gripper gripped at the tip. At this time, the paper 14 is conveyed in a non-contact state with the printing surface inside.

  FIG. 2 is a side sectional view showing a schematic configuration of the impression cylinder. FIG. 3 is a development view of the peripheral surface of the impression cylinder.

  As shown in the figure, the impression cylinder 216 is formed in a drum shape, and grippers 500 and 502 are provided at two locations on the peripheral surface thereof. The two grippers 500 and 502 are provided at positions facing each other, and the sheet 14 is rotated and conveyed with either one of the grippers 500 and 502 gripping the leading end.

  Further, as shown in FIG. 3, a large number of suction holes 508 are formed in a predetermined arrangement on the peripheral surface of the impression cylinder 216. At the time of rotational conveyance, the sheet 14 is conveyed while being sucked and held by the negative pressure suction on the peripheral surface of the pressure drum 216 by sucking air from the suction holes 508 toward the inside of the pressure drum 216.

  In addition, an opening 504 for purging ink is formed on the peripheral surface of the impression cylinder 216. The opening 504 is formed in a long hole shape corresponding to the width of the ink heads 210K, 210C, 210M, and 210Y, and is formed so as to avoid the holding area 507 of the paper 14. Each of the ink heads 210K, 210C, 210M, and 210Y maintains the ejection performance by purging in accordance with the passage timing of the opening 504. The ink purged to the opening 504 is collected in a collection tank (not shown) via the suction channel 506.

  A shielding plate 503 is provided below the pressure drum 216 (positions facing the ink heads 210K, 210C, 210M, and 210Y with the pressure drum 216 interposed therebetween). The shielding plate 503 is formed in an arc shape along the peripheral surface of the impression cylinder 216, and is disposed in the vicinity of the outer peripheral surface of the impression cylinder 216. The shielding plate 503 prevents the suction pressure from being lowered by the suction hole 508 being opened after the pressure drum 216 delivers the paper 14 to the transfer drum 304 of the drying unit 30.

  The impression cylinder 216 configured as described above grips the leading end portion of the sheet 14 with one of the grippers 500 and 502 and rotates and conveys the sheet 14 while sucking and holding it with the suction hole 508.

  The pressure drum 216 is rotated by a motor (not shown), and the air in the pressure drum 216 is sucked by a vacuum pump (not shown).

  Each of the ink heads 210K, 210C, 210M, and 210Y is composed of a line head corresponding to the width of the paper 14, and drops ink droplets from a nozzle row formed on a surface (ejection surface) facing the impression cylinder 216. An image is formed on the printing surface of the paper 14 that is ejected and rotated and conveyed to the impression cylinder 86.

  Hereinafter, the structure of the ink heads 210K, 210C, 210M, and 210Y will be described. In addition, since the structure of each ink head 210K, 210C, 210M, 210Y is common, an ink head is shown by the code | symbol 210 here and the structure is demonstrated.

  FIG. 4A is a plan perspective view showing a schematic structure of the ink head, and FIG. 4B is an enlarged view of a part thereof.

  As shown in FIG. 4A, in the ink head 210 of this example, the pressure chambers 282 that are individually provided corresponding to the respective nozzles 281 are arranged in a staggered pattern. Densification is achieved. That is, by arranging in this way, it is possible to narrow the interval between the nozzles 281 that are projected so as to be aligned along the longitudinal direction of the head (the direction orthogonal to the paper conveyance direction), thereby increasing the height of the nozzles. Densification is achieved.

  As shown in FIG. 4B, each pressure chamber 282 has a substantially square planar shape, and an outlet to the nozzle 281 is provided at one of the diagonal corners. . In addition, an ink supply port 284 is provided on the other side.

  FIG. 5 is a cross-sectional view taken along line BB in FIG. As shown in the figure, the supply port 284 provided in each pressure chamber 282 is in communication with a common channel 285. The common channel 285 communicates with an ink tank (not shown) that is not shown. Ink is supplied from the ink tank to the common flow path 285, and is supplied from the common flow path 285 to each pressure chamber 282 through the supply port 284.

  A piezo element 288 having an individual electrode 287 is joined to a pressure plate (vibrating plate that also serves as a common electrode) 286 constituting the top surface of the pressure chamber 282. The piezo element 288 is deformed by applying a drive voltage between the individual electrode 287 and the common electrode. When the pressure plate 286 is deformed, the volume of the pressure chamber 282 is changed, and the ink is ejected as droplets from the nozzle 281 due to the pressure change accompanying this. Further, when the displacement of the piezo element 288 returns to the original state after ink ejection, new ink is filled into the pressure chamber 282 from the common flow path 285 through the supply port 284 accordingly.

  The ink head 210 configured as described above can record a desired image on the paper 14 by controlling the ejection timing of each nozzle 281 in accordance with the conveyance speed of the paper 14.

  In this example, a method in which ink is ejected as droplets by deformation of an actuator 288 typified by a piezoelectric element (so-called piezo ink jet method) is adopted, but the method for ejecting ink is limited to this. It is not a thing. In addition, various systems such as a thermal ink jet system can be adopted.

  In this example, the structure of the ink heads 210K, 210C, 210M, and 210Y has been described. However, the treatment liquid applying apparatus 202 has the same configuration.

<Dry section>
The drying unit 30 evaporates moisture contained in the ink deposited on the printing surface of the paper 14 and dries it.

  The drying unit 30 mainly receives the sheet 14 from the impression cylinder 216 of the drawing unit 28 and rotates and conveys the sheet 14, the impression cylinder 306 that receives and rotates the sheet 14 from the transfer cylinder 304, and the impression cylinder The drying unit 308 is configured to heat the paper 14 rotated and conveyed by 306 and evaporate water contained in the ink.

  The transfer drum 304 is formed in a drum shape, and is rotated by being driven by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the transfer drum 304. The paper 14 is rotated and conveyed with its gripper gripped at the tip. At this time, the paper 14 is conveyed in a non-contact state with the printing surface inside.

  The impression cylinder 306 is formed in a drum shape and is driven to rotate by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the impression cylinder 306, and the paper 14 is rotated and conveyed with its leading end held by the gripper. Further, the peripheral surface of the pressure drum 306 is charged, and the sheet 14 is rotated and conveyed while being attracted and held on the peripheral surface of the pressure drum 306 by electrostatic attraction force. Further, the impression cylinder 306 incorporates a heater (not shown), and the peripheral surface is heated to a constant temperature by the heater. The sheet 14 is heated from the back side by being conveyed while being sucked and held on the peripheral surface of the heated impression cylinder 306.

  The drying unit 308 includes an IR heater (not shown) and a blower fan, and blows hot air at a predetermined temperature on the surface (printing surface) of the paper 14 that is rotated and conveyed by the impression cylinder 306 at a predetermined wind speed. When the hot air is blown from the drying unit 308, the water in the ink droplets deposited on the printing surface evaporates and the paper 14 is dried.

  In addition to the electrostatic adsorption, the impression cylinder 306 may be provided with a plurality of adsorption holes on the peripheral surface like the impression cylinder 216 of the drawing unit 28, and may be adsorbed and conveyed by negative pressure suction.

<Fixing part>
The fixing unit 32 fixes the image on the paper 14 by heating and pressurizing the paper 14 from which water in the ink has been removed with a fixing roller.

  The fixing unit 32 mainly receives the sheet 14 from the impression cylinder 306 of the drying unit 30 and rotates and conveys the sheet 14, the impression cylinder 326 that receives and rotates the sheet 14 from the transfer cylinder 324, and the impression cylinder It is composed of three fixing rollers 328 a, 328 b, and 328 c that heat and press the paper 14 that is rotated and conveyed by 326.

  The transfer drum 324 is formed in a drum shape, and is rotated by being driven by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the transfer drum 324. The paper 14 is rotated and conveyed with its gripper gripped at the tip. At this time, the paper 14 is conveyed in a non-contact state with the printing surface inside.

  The impression cylinder 326 is formed in a drum shape, and is driven to rotate by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the impression cylinder 306, and the paper 14 is rotated and conveyed with its leading end held by the gripper.

  Each of the three fixing rollers 328a, 328b, and 328c includes a heater (not shown) and is heated to a predetermined temperature. The fixing rollers 328a, 328b, and 328c are provided so as to be movable forward and backward with respect to the pressure drum 326, and are pressed against the pressure drum 326 with a predetermined pressing force in accordance with the passage timing of the paper 14. As a result, the paper 14 is heated and pressed by the fixing rollers 328a, 328b, and 328c, and the image formed on the printing surface is fixed to the paper 14.

<Output section>
The paper discharge unit 34 discharges the paper 14 on which the image is fixed by the fixing unit 32. The paper discharge unit 34 mainly receives the paper 14 from the pressure drum 326 of the fixing unit 32 and rotates and conveys the paper 14. The paper discharge unit 34 receives the paper 14 from the transfer drum 344 and discharges the paper 14 to the outside of the apparatus. And measuring means 348.

  The transfer drum 344 is formed in a drum shape and is rotated by being driven by a motor (not shown). A gripper (not shown) is provided on the peripheral surface of the transfer drum 344. The paper 14 is rotated and conveyed with its gripper gripped at the tip. At this time, the paper 14 is conveyed in a non-contact state with the printing surface inside.

  A paper discharge tray 346 receives the paper 14 from the transfer cylinder 344 and discharges it outside the apparatus.

  The measuring means 348 is composed of a CCD line sensor, an infrared thermometer, an infrared moisture meter, a gloss meter, and the like, and images a check pattern recorded on the paper 14 passing on the paper discharge tray to detect a discharge failure or the like. Inspect for presence or absence, measure moisture content, surface temperature, glossiness, etc.

<Control system>
FIG. 6 is a block diagram illustrating a schematic configuration of a control system of the ink jet printer according to the present embodiment.

  As shown in the figure, the inkjet printer 10 includes a system controller 400, a communication interface 402, an image memory 404, a paper feed control unit 406, a permeation suppression agent application control unit 408, a processing liquid application control unit 410, and a drawing control unit 412. A drying control unit 414, a fixing control unit 416, a paper discharge control unit 418, an operation unit 420, a display unit 422, and the like.

  The system controller 400 is a control unit that controls each unit of the inkjet printer 10 and is an arithmetic processing unit that performs various arithmetic processes, and includes a CPU, a ROM, a RAM, and the like. The system controller 400 controls each part of the inkjet printer 10 according to a predetermined control program. The ROM stores a control program executed by the system controller 400 and various data necessary for control.

  The communication interface 402 is an interface unit that receives image data sent from the host computer 430. The image data sent from the host computer 430 is taken into the inkjet printer 10 via the communication interface 402.

  The image memory 404 is a storage unit that temporarily stores image data, and data is read and written through the system controller 400. Image data captured from the host computer 430 via the communication interface 402 is stored in the image memory 404.

  The paper feed control unit 406 controls driving of each part (the adhesive roller 37, the transfer cylinder 38, etc.) constituting the paper feed unit 22 in accordance with a command from the system controller 400.

  The permeation suppression agent application control unit 408 is configured according to a command from the system controller 400 (the impression cylinder 40, the permeation suppression agent application device 42, the paper presser 44, the permeation suppression agent drying unit 46). Etc.) is controlled.

  The processing liquid application control unit 410 drives each part (the transfer cylinder 85, the pressure drum 86, the processing liquid application device 202, the processing liquid drying unit 204, etc.) constituting the processing liquid application unit 26 in response to a command from the system controller 400. To control.

  The drawing control unit 412 controls driving of each unit (the transfer cylinder 214, the impression cylinder 216, the ink heads 210K, 210C, 210M, 210Y, etc.) constituting the drawing unit 28 in accordance with an instruction from the system controller 400.

  The drying control unit 414 controls driving of each unit (the transfer cylinder 304, the impression cylinder 306, the drying unit 308, etc.) constituting the drying unit 30 in accordance with an instruction from the system controller 400.

  The fixing control unit 416 controls driving of each unit (the transfer cylinder 324, the pressure cylinder 326, the fixing rollers 328a, 328b, 328c, etc.) constituting the fixing unit 32 in accordance with an instruction from the system controller 400.

  The paper discharge control unit 418 controls the drive of each part (the transfer cylinder 344, the measuring unit 348, etc.) constituting the paper discharge unit 34 in accordance with an instruction from the system controller 400.

  The operation unit 420 includes necessary operation means (operation buttons, a keyboard, a touch panel, and the like), and outputs operation information input from the operation means to the system controller 400.

  The display unit 422 includes a required display device (LCD panel or the like), and displays required information on the display device in accordance with an instruction from the system controller 400.

  As described above, the image data is taken into the inkjet printer 10 from the host computer 430 via the communication interface 402 and stored in the image memory 404. The system controller 400 performs necessary signal processing on the image data stored in the image memory 404 to generate dot data. Then, the image represented by the image data is printed on the paper 14 by controlling the driving of the ink heads 210K, 210C, 210M, and 210Y of the drawing unit 28 according to the generated dot data.

  The dot data is generally generated by performing color conversion processing and halftone processing on image data.

  The color conversion processing is processing for converting image data expressed in sRGB or the like (for example, RGB 8-bit image data) into color data for each color of ink used in the ink jet printer (in this example, KCMY color data). is there.

  The halftone process is a process of converting the color data of each color generated by the color conversion process into dot data of each color (in this example, KCMY dot data) by a process such as error diffusion.

  The system controller 400 performs color conversion processing and halftone processing on the image data to generate dot data for each color of CMYK. Then, by controlling the driving of the corresponding ink heads 210K, 210C, 210M, and 210Y according to the generated dot data for each color, the image represented by the image data is printed on the paper 14.

≪Overview of printing operation≫
Next, the printing operation by the inkjet printer 10 of the present embodiment configured as described above will be described.

  The paper 14 fed from the paper feeding unit 22 is first transported to the permeation suppression agent applying unit 24, where a permeation suppression agent is applied to a predetermined area of the printing surface and dried. In the permeation suppression agent applying unit 24, the sheet 14 is rotated and conveyed by the impression cylinder 40, and the application roller 48 is brought into contact with the printing surface of the rotation and conveyance of the sheet 14 to apply the permeation suppression agent to a predetermined region. To do. Then, hot air is blown from the permeation suppression agent drying unit 46 onto the coated paper 14 and dried.

  The paper 14 coated with the permeation suppressor is then transported to the treatment liquid application unit 26 where the treatment liquid is applied to a predetermined area of the printing surface and dried. In the processing liquid application unit 26, the paper 14 is rotated and conveyed by the impression cylinder 86, and the processing liquid is ejected onto the printing surface of the paper 14 being rotated and conveyed by the processing liquid application device 202 configured by a line head. Then, the treatment liquid is applied to the predetermined area. Then, hot air is blown from the treatment liquid drying unit 204 to the applied paper 14 and dried.

  The paper 14 to which the treatment liquid has been applied is then conveyed to the drawing unit 28 where black, cyan, magenta, and yellow ink droplets are ejected onto the image forming area of the printing surface, and a color image is formed. Drawn. In the drawing unit 28, the paper 14 is rotated and conveyed while being suctioned and held by the impression cylinder 216, and black, cyan, magenta, and yellow ink heads 210K, 210C, and 210 are printed on the printing surface of the paper 14 that is rotated and conveyed. A droplet of ink of each color is ejected with 210M and 210Y to draw a color image in the image forming area.

  The paper 14 on which the image has been drawn is then transported to the drying unit 30 where the water in the ink deposited on the printing surface is evaporated and dried. In the drying unit 30, the paper 14 is rotated and conveyed while being sucked and held by the impression cylinder 306, and is dried by blowing hot air onto the paper 14 being rotated and conveyed by the drying unit 308.

  The dried paper 14 is then conveyed to the fixing unit 32 and the image drawn on the printing surface is fixed on the paper 14. In the fixing unit 32, the sheet 14 is rotated and conveyed by the pressure drum 326, and the fixing rollers 328 a, 328 b, and 328 c are pressed against the rotated and conveyed sheet 14, and heated and pressurized to thereby form an image on the sheet 14. To settle.

  The sheet 14 on which the image is fixed is conveyed to a sheet discharge unit 34 and is discharged outside the apparatus.

≪Relationship between permeation inhibitor application area, treatment liquid application area, and image formation area≫
As described above, in the ink jet printing apparatus according to the present embodiment, a permeation inhibitor is applied to the paper 14 in advance, and a treatment liquid is applied thereon, and then ink is ejected onto the paper 14 to form an image. I'm drawing.

  FIG. 7 is a diagram illustrating a relationship among a permeation inhibitor application region, a treatment liquid application region, and an image formation region.

  As shown in the figure, the image forming area is set as a rectangular area having four sides parallel to the four sides of the paper 14, leaving a margin area with a predetermined width around the image forming area. Set to the center position (shaded area in the figure).

  The application area of the penetration inhibitor and the treatment liquid application area are set so as to cover the entire image forming area. That is, the permeation suppressor application area and the treatment liquid application area are set to a wider area than the image forming area. In this example, the permeation inhibitor application region and the treatment liquid application region are set to the same region, and are set so as to protrude by a predetermined amount from the periphery of the image forming region (region in the chain line in the figure).

  As described above, normally, the application area of the penetration inhibitor and the application area of the treatment liquid are set so as to cover the entire image forming area. Therefore, normally, the processing liquid is not applied to the blank area around the image forming area.

  However, in the inkjet printer 10 of the present embodiment, as shown in FIG. 8, the treatment liquid is also applied to the blank area formed around the image forming area (no penetration inhibitor is applied). This is because the paper 14 can be transported in a more stable state when the paper 14 is sucked and transported by the impression cylinder 216 in the drawing unit 28 at the subsequent stage.

  That is, by applying the treatment liquid also to the blank area, the rigidity of the paper 14 is lowered, and thereby the paper 14 is easily brought into close contact with the peripheral surface of the impression cylinder 216 formed of a curved surface. In addition, by applying the treatment liquid to the blank area, the airtightness is improved, thereby making it possible to reliably adsorb.

  As described above, by applying the treatment liquid to the blank area, the paper 14 can be stably conveyed when the paper 14 is sucked and conveyed by the impression cylinder 216.

  In addition, since the treatment liquid applied to the blank area is intended to reduce the rigidity of the paper 14 and improve the airtightness, the liquid applied within a range in which such an object can be achieved. The amount is set.

  Normally, the processing liquid applied to the image forming area is applied in a liquid amount necessary and sufficient to agglomerate the ink, but the processing liquid applied to the blank area reduces the rigidity of the paper 14 and improves the airtightness. Therefore, the amount is set to be larger than the amount of the processing liquid applied to the image forming area. However, if the amount of liquid to be applied is excessive, cockling of the paper 14, contamination of the apparatus, back flow, and the like occur.

  Although the application | coating form of the process liquid provided to a blank area | region is not specifically limited, In order to suppress wet spreading etc., it is preferable to provide in the shape of a narrow line. As a result, it is possible to prevent the cockling, the contamination of the apparatus, the back flow, and the like while reducing the rigidity of the paper 14 and improving the airtightness.

  Further, the treatment liquid applied to the blank area does not necessarily need to be applied to all sides of the blank area. It is good also as a structure given only to the margin area | region of a rear end side, and good also as a structure given only to the margin area | region of both right and left sides.

  Since the paper 14 is rotated and conveyed to the impression cylinder with the rear end being free, the rear end side tends to float (the blank area is gripped by the gripper on the front end side). Therefore, the trailing edge can be effectively prevented from being lifted by applying a treatment liquid having a volume larger than that applied to the image forming area to the margin area on the trailing edge side. In particular, when the paper is thick, the float becomes prominent. Therefore, when the processing liquid having a liquid amount larger than that applied to the image forming area is applied to the blank area on the rear end side of the paper 14, the float is effectively lifted. Can be prevented.

  Further, by applying a treatment liquid having a volume larger than that applied to the image forming area to the blank area at the tip, the adsorption of the holding portion with the gripper is stabilized.

  In addition, by applying processing liquid with a volume larger than that applied to the image forming area to the left and right margin areas, the rigidity in the transport direction is reduced, airtightness is improved, and more stable paper suction is possible. become.

  Hereinafter, a specific example will be described.

  In the image forming area, the droplet deposition density is set to 600 dip × 600 dip, the droplet ejection amount is set to 5 pl, and the treatment liquid is applied with an average liquid thickness of 4 to 6 μm.

  On the other hand, the treatment liquid is applied to the blank area at an average liquid thickness of 10 to 40 μm with a droplet ejection density of 1200 dip × 1200 dip and a droplet ejection volume of 5 to 20 pl.

When printing coated paper (art paper, coated paper, lightweight coated paper, etc.) is used as the paper, the thickness of the coating layer is about 5 to 20 μm, and the thickness of the base paper is 60 μm (thin) basis weight 73.3 g / ^{m 2,} wales deflection amount 40 to 50 mm), thick in 260 .mu.m (basis weight 279 g / ^{m 2,} a long grain deflection amount 10 to 20 mm) of about (a wale deflection amount, width 250mm This is the amount of deflection (bending rigidity) when the vertical paper sheet is stretched 150 mm.) In the case of coated paper for printing, the applied liquid penetrates to a depth of about twice the average liquid thickness.

  In the case of a thin coated paper for printing having a thickness of 60 μm, if a treatment liquid having an average liquid thickness of 10 μm is applied, the treatment liquid that has passed through the coating layer has a depth of 20 μm, which is about 1/3 of the thickness of the paper. Therefore, it is absorbed by the paper fiber of the base paper layer, thereby reducing the rigidity and improving the airtightness.

  In the case of a thick coated paper for printing having a thickness of 260 μm, if a treatment liquid having an average liquid thickness of 40 μm is applied, the treatment liquid that has passed through the coating layer is about 1/3 of the thickness of the recording medium. Since it penetrates to a depth of 80 μm, it is absorbed by the paper fibers of the base paper layer, thereby reducing the rigidity and improving the airtightness.

  Since the rigidity of the paper is roughly proportional to the cube of the thickness, it is particularly effective for thick paper.

  The treatment liquid is preferably applied to the blank area of the paper 14 so as to form a line at a certain distance from the image forming area. Specifically, it is preferable to give a width of 2 to 3 mm with a distance of 1 to 2 mm. Thereby, even when the amount of liquid is large, cockling or the like is unlikely to occur, and stable permeation with suppressed wetting and spreading becomes possible. In this case, it is preferable to suppress the application amount at both ends of the line. Thereby, wetting and spreading of the treatment liquid can be more effectively suppressed.

  If the treatment liquid is ejected onto the blank area at the rear end of the paper 14, the rigidity of the rear end of the paper 14 is lowered and the airtightness is increased, so that the suction of the paper 14 to the impression cylinder 216 of the drawing unit 28 is stable. To do. It can be applied to the margin area at the leading edge or to the margin areas at both the left and right ends, and if it is applied to all the margin areas on the four outer sides of the paper 14, the suction is further stabilized.

  It should be noted that no permeation inhibitor is applied to the blank area. As a result, the treatment liquid penetrates into the paper 14, and even if the treatment liquid is dried by the treatment liquid drying unit 204 after the treatment liquid is applied, the applied treatment liquid penetrates and remains in the paper 14, thereby reducing the rigidity of the paper 14. The effect of improving the airtightness lasts until the airtightness is conveyed to the impression cylinder 216 of the drawing unit 28.

Furthermore, addition in the above example has been described paper up to 260 .mu.m (basis weight 279 g / ^{m 2),} the cardboard such as thickness 420 [mu] m (basis weight 350 g / ^{m 2),} to increase the application amount of the treatment liquid, It is also possible to increase the permeation time by reducing the conveying speed.

  As described above, it is preferable to change the treatment liquid applied to the blank area according to the thickness of the paper. In this case, it is preferable to apply at a thickness that is ½ of the thickness of the paper.

  Further, when coated paper is used as the paper, it is preferable to apply the treatment liquid to the blank area with a thickness equal to or greater than the coating layer in order to sufficiently reduce the rigidity and improve the airtightness.

  As described above, in the inkjet printer 10 according to the present embodiment, when the processing liquid is applied to the paper 14, the processing liquid having a liquid amount larger than that applied to the image forming area is applied to the blank area around the image forming area. By imparting, the rigidity of the paper 14 is reduced, the airtightness is improved, and the conveyance stability of the paper 14 sucked and conveyed by the drawing unit 28 at the subsequent stage is ensured. This makes it possible to form a stable image.

≪Application to drawing part≫
In the above example, when the processing liquid is applied to the paper 14, the rigidity of the paper 14 is reduced by applying a processing liquid having a liquid amount larger than that applied to the image forming area to the blank area around the image forming area. Further, the airtightness is improved, and the conveyance stability of the sheet 14 sucked and conveyed by the drawing unit 28 at the subsequent stage is ensured.

  Also in the drawing unit 28, when ink is applied to the paper 14, by applying ink of a liquid amount higher than that applied to the image forming region to the blank area around the image forming region, the drying unit 30 in the subsequent stage provides the impression cylinder. Stable conveyance of the sheet 14 sucked and conveyed by the 306 can be ensured. That is, by applying ink of a liquid amount larger than that applied to the image forming area to the blank area around the image forming area, the rigidity of the paper 14 is reduced and airtightness is reduced as in the case of applying the processing liquid. As a result, the sheet 14 can be stably conveyed when being sucked and conveyed by the pressure drum 306 of the drying unit 30.

  Hereinafter, a specific example will be described.

  When the droplet ejection density is 1200 dpi × 1200 dpi and the droplet ejection amount is 2.5 pl, the average droplet thickness of 100% solid color is 6 μm or less, and the maximum droplet ejection amount for multiple colors Control to 250% (= 2.5 order color: average liquid thickness 15 μm) or less.

  On the other hand, in a blank area, an ink having an average liquid thickness of 6 μm is applied to the thin paper having a thickness of 60 μm by applying an ink with an average liquid thickness of 10 μm with an ink head located downstream of Y or K. Dripping. In addition, on a thick paper having a thickness of 260 μm to which a processing liquid having an average liquid thickness of 400 μm is applied in a line shape, ink having an average liquid thickness of 15 μm is ejected by a head positioned downstream of M, Y, and K.

  It should be noted that the amount of ink ejected onto the margin area is not limited to 250%, and can be 400% ejected using all ink heads. It is effective when the drying amount in the drying unit 30 is large.

  As described above, in the drawing unit 28 as well, by applying ink of a liquid amount larger than that applied to the image forming region to the marginal region around the image forming region, the subsequent drying unit 30 electrostatically attracts the pressure drum 306. Thus, it is possible to ensure the conveyance stability of the sheet 14 being conveyed.

<< Other forms of treatment liquid application apparatus >>
In the above-described embodiment, the treatment liquid application device configured by the line head is configured to apply the treatment liquid by applying droplets to a predetermined area of the paper 14, but the configuration of the treatment liquid application device is limited to this. It is not a thing. It can also be set as the structure apply | coated with an application | coating roller similarly to the penetration inhibitor coating device 42.

  FIG. 9 is a perspective view showing another example of the treatment liquid application apparatus. As shown in the figure, the treatment liquid application device 600 of this example applies the treatment liquid by applying it with an application roller. The treatment liquid application apparatus 600 is applied to the application roller 602, a motor 604 that rotationally drives the application roller 602, a spray (not shown) that applies a treatment liquid to the application roller 602, and a spray. The squeegee blade 606 for removing excess processing liquid from the processing liquid and the main blade 608 for removing all processing liquid applied to the application roller 602 are provided.

  The application roller 602 is formed of a spiral roller having a spiral groove formed on the peripheral surface thereof, and is supported so as to be rotatable and movable back and forth with respect to an impression cylinder (not shown). Then, it is supported by an advancing / retreating mechanism (not shown) so as to be able to contact / separate from the impression cylinder.

  The motor 604 is driven to rotate at a constant rotation speed, and the rotation is transmitted to the application roller 602 via the belt 610.

  The spray is installed at a position below the application roller 602, and sprays the processing liquid from below the application roller 602 toward the tip of the squeegee blade 606. The spray is provided so that the spray width can be arbitrarily adjusted. By adjusting the spray width, the application width of the treatment liquid to the application roller 602 is adjusted.

  The squeegee blade 606 is pivotably supported by a shaft 606A provided at both ends supported by a bearing (not shown), and the tip of the squeegee blade 606 is provided so as to come into contact with / separate from the peripheral surface of the application roller 602. Yes. Then, the front end is urged by an urging means (not shown) so as to press and contact the peripheral surface of the application roller 602. This squeegee blade 606 adheres to the outside of the groove formed in the application roller 602 out of the excess liquid of the process liquid applied to the peripheral surface of the application roller 602 by spraying. Scraped off from the coating roller 602.

  The main blade 608 is supported by a shaft (not shown) on a shaft 608A provided at both ends so that the main blade 608 can swing freely. A tip of the main blade 608 is provided so as to contact / separate from the peripheral surface of the application roller 602. Yes. The tip is biased by a biasing means (not shown) so as to be separated from the peripheral surface of the application roller 602.

  An eccentric cam 612 is in contact with the rear end portion of the main blade 608. The eccentric cam 612 is rotated by being driven by the cam motor 614 to bring the main blade 608 into contact with / separate the peripheral surface of the application roller 602. When the main blade 608 is brought into contact with the peripheral surface of the application roller 602, the processing liquid adhering to the peripheral surface is removed.

  According to the processing liquid application device 600 configured as described above, the processing liquid is applied to the peripheral surface of the application roller 602 with a predetermined width by spraying. Then, surplus liquid is removed from the processing liquid applied to the peripheral surface of the application roller 602 by spraying by the squeegee blade 606, whereby the processing liquid is uniformly applied to the peripheral surface of the application roller 602. Further, the processing liquid applied to the peripheral surface of the application roller 602 is removed when the main blade 608 is brought into contact with the peripheral surface of the application roller 602, whereby the processing liquid is selectively applied to the peripheral surface of the application roller 602. Is granted.

  By applying the application roller 602 to which the processing liquid is applied in this manner against the printing surface of the paper 14 that is rotated and conveyed by the impression cylinder, the processing liquid is applied to the printing surface of the paper 14. At this time, by adjusting the application width of the treatment liquid to be applied to the application roller 602, the application width of the treatment liquid to be applied to the paper 14 is adjusted, and the application area in the circumferential direction of the treatment liquid to be applied to the application roller 602 is adjusted. By adjusting, the application area | region of the paper conveyance direction of the process liquid provided to the paper 14 is adjusted.

  Accordingly, by adjusting the application area in the circumferential direction of the processing liquid applied to the application roller 602, the processing liquid is uniformly applied to the entire surface of the image forming area, and the leading edge margin area and / or the trailing edge margin area of the paper 14 is applied. Can be applied in the form of a line of treatment liquid.

  In the above method, the amount of the processing liquid applied to the image forming area and the amount of the processing liquid applied to the leading edge margin area and / or the trailing edge margin area are the same, but are applied to each area. When adjusting the amount of the processing liquid to be performed, it is performed as follows. That is, since the amount of the processing liquid applied to the paper 14 is adjusted by the squeegee blade 606, the squeegee blade 606 is configured to be arbitrarily contacted / separated from the application roller 602. For example, like the main blade 608, it can be arbitrarily contacted / separated by an eccentric cam. As a result, the amount of treatment liquid applied to the application roller 602 can be arbitrarily adjusted in the circumferential direction of the application roller 602. As a result, the amount of treatment liquid applied to the paper 14 can be arbitrarily adjusted in the transport direction. can do.

  Since the squeegee blade 606 and the main blade 608 need only be able to contact / separate arbitrarily from the peripheral surface of the application roller 602, the contact / separation mechanism is not limited to the mechanism using the eccentric cam described above. Absent. In the case of using the eccentric cam, for example, by forming a groove on the peripheral surface of the eccentric cam, the squeegee blade 606 and the main blade 608 can be temporarily separated from the peripheral surface of the application roller 602.

≪Other forms of impression cylinder≫
The impression cylinder of the above embodiment is configured to grip the blank area at the front end of the paper with a gripper provided on the peripheral surface thereof and rotate and convey the paper. Further, the rear end of the paper 14 is punched with a pin. A holding mechanism may be provided.

  FIG. 10 is a side sectional view showing a schematic configuration of an impression cylinder provided with a perforation holding mechanism.

  As shown in the figure, clampers 700 and 702 for punching and holding the rear end of the paper 14 are provided at two locations on the peripheral surface of the impression cylinder 216.

  The clampers 700 and 702 are formed in an arc shape so as to form a part of the circumferential surface of the impression cylinder 216, and a plurality of pin 704 and 706 formed in a needle shape are formed at the tip of the clamper 216. Projecting in the outer circumferential direction.

  The clampers 700 and 702 are swingably supported by swing shafts 708 and 710 provided on the pressure drum 216, and are driven by driving means (not shown) so that pins 704 and 706 are connected to the pressure drum 216. Pins 704 and 706 are provided movably between a position protruding from the peripheral surface (the position in FIG. 10) and a position retracting from the peripheral surface of the impression cylinder 216.

  According to the impression cylinder 216 configured as described above, the paper 14 is held with the leading blank area gripped by the grippers 500 and 502 and the trailing blank area punched by the pins 704 and 706. . As a result, the trailing edge of the sheet can be reliably prevented from floating, and more stable conveyance can be achieved. Even in the case where the pins 704 and 706 are stabbed and held at the rear end of the paper 14 in this way, in this embodiment, the processing liquid is applied to the rear end margin area of the paper 14 and the rigidity is increased. Since it is lowered, the pins 704 and 706 can be easily inserted into the paper 14. Thereby, it is possible to stably hold the hole without causing burrs or the like. In particular, it works effectively when the paper 14 is thick.

  The clampers 700 and 702 are driven so that the pins 704 and 706 protrude in accordance with the timing of receiving the paper 14. Then, the pins 704 and 706 are driven so as to retract in accordance with the delivery timing of the paper 14.

  In order to ensure the perforation by the pins 704 and 706, a pressure roller is provided on the peripheral surface of the impression cylinder 216, and when the pins 704 and 706 are inserted into the paper 14, the paper 14 is held by the pressure roller. May be.

  Further, in the above example, the example in which the perforation holding mechanism is installed in the impression cylinder 216 of the drawing unit 28 has been described, but the perforation holding mechanism can be similarly provided for other impression cylinders. Thereby, the paper 14 can be conveyed more stably.

≪Other forms of treatment liquid application≫
In the above embodiment, the processing liquid is applied to a part of the blank area (for example, provided in a line shape), but the processing liquid may be applied to the entire blank area. That is, the processing liquid may be applied to the entire printing surface of the paper, and the amount of the processing liquid applied to the blank area may be larger than that applied to the image forming area.

  In the above embodiment, the permeation inhibitor is applied to the paper, but the permeation inhibitor is not necessarily provided.

<< Recording medium >>
In the above embodiment, an example in which printing paper, particularly coated paper, is used as the recording medium has been described. However, application of the present invention is not limited to this. If the recording medium has an absorptivity, the same effects can be obtained.

<< Composition of penetration inhibitor and treatment liquid >>
<Processing liquid>
The processing liquid used in the present embodiment is an acidic liquid having an action of aggregating the color materials contained in the ink ejected from the ink heads 210K, 210C, 210M, and 210Y toward the paper 14 in the drawing unit 28. preferable. Specifically, a treatment solution described in Table 2 below, or a treatment solution to which an acid such as 2-pyrrolidone-5-carboxylic acid, phosphoric acid, succinic acid, or citric acid is added can be considered.

  In addition, a high-boiling-point solvent such as glycerin or a small amount of polymer particles such as LX-1 described in Table 1 or LX-2 described in Table 4 is added to suppress the penetration of the treatment liquid, thereby reducing the permeation suppression layer. It is also possible to make it unnecessary. For this reason, when the treatment liquid having such a penetration inhibiting effect is applied by the penetration inhibitor coating apparatus 42, the pressure drum 86 of the treatment liquid application unit 26, the treatment liquid application apparatus 202, the treatment liquid drying unit 204, and the like. Is no longer necessary.

<Adjustment of each solution>
Examples of adjustment of the permeation inhibitor, the treatment liquid, and the ink used in the ink jet printer according to the present embodiment are shown below.

i. Permeation inhibitor A dispersion solution of 10 g of dispersion stabilizing resin [Q-1] having the structure shown in [Chemical Formula 1] below, 100 g of vinyl acetate and 384 g of Isopar H (trade name of Exxon), a temperature of 70 ° C. with stirring in a nitrogen stream Warmed to.

  As a polymerization initiator, 0.8 g of 2,2′-azobis (isovaleronitrile) (abbreviation AIVN) was added and reacted for 3 hours. 20 minutes after the addition of the initiator, white turbidity occurred, and the reaction temperature rose to 88 ° C. Further, 0.5 g of the initiator was added and reacted for 2 hours, and then the temperature was raised to 100 ° C. and stirred for 2 hours to distill off unreacted vinyl acetate. After cooling, it was passed through a 200-mesh nylon cloth, and the resulting white dispersion was a latex with a good monodispersity having a polymerization rate of 90% and an average particle size of 0.23 μm. The particle size was measured with CAPA-500 (manufactured by Horiba, Ltd.).

  A part of the white dispersion was centrifuged (rotation speed 1 × 10 4 rpm, rotation time 60 minutes) to collect the precipitated resin particles, dried, and the weight average of the resin particles When molecular weight (Mw), glass transition point (Tg), and minimum film-forming temperature (MFT) were measured, Mw was 2 × 10 5 (polystyrene equivalent GPC value), Tg was 38 ° C., and MFT was 28 ° C.

ii. Treatment liquid (Adjustment of treatment liquid T-1)
The treatment liquid was adjusted with the composition shown in Table 2 below, and the physical properties of the obtained reaction liquid were measured. As a result, the viscosity was 4.9 mPa · s, the surface tension was 24.3 mN / m, and the pH was 1.5.

  By using these processing liquids, it is possible to apply a processing liquid that is excellent in ejectability of the head and wetness of the recording medium.

iii. Ink (Preparation of polymer dispersant P-1)
In a 1000 ml three-necked flask equipped with a stirrer and a condenser, 88 g of methyl ethyl ketone was added and heated to 72 ° C. under a nitrogen atmosphere. Here, 50 g of methyl ethyl ketone was mixed with 0.85 g of dimethyl 2,2′-azobisisobutyrate, 60 g of benzyl methacrylate, A solution in which 10 g of methacrylic acid and 30 g of methyl methacrylate were dissolved was dropped over 3 hours. After completion of the dropwise addition, the reaction was further continued for 1 hour, and then a solution in which 0.42 g of dimethyl 2,2′-azobisisobutyrate was dissolved in 2 g of methyl ethyl ketone was added, heated to 78 ° C. and heated for 4 hours. The obtained reaction solution was reprecipitated twice in a large excess amount of hexane, and the precipitated resin was dried to obtain 96 g of polymer dispersant P-1.

  The composition of the obtained resin was confirmed by 1H-NMR, and the weight average molecular weight (Mw) determined by GPC (Gel Permeation Chromatography) was 44600. Furthermore, when the acid value of this polymer was calculated | required by the method of JIS specification (JISK0070: 1992), it was 65.2 mgKOH / g.

(Preparation of cyan dispersion)
Pigment Blue 15: 3 (Phthalocyanine-A220 manufactured by Dainichi Seika Co., Ltd.), 5 parts of the polymer dispersant P-1 obtained above, 42 parts of methyl ethyl ketone, and 1 mol / L NaOH aqueous solution. 5.5 parts and 87.2 parts of ion-exchanged water were mixed and dispersed in a bead mill using 0.1 mmΦ zirconia beads for 2 to 6 hours.

  Methyl ethyl ketone was removed from the obtained dispersion at 55 ° C. under reduced pressure, and a part of water was further removed to obtain a cyan dispersion having a pigment concentration of 10.2% by mass.

  As described above, a cyan dispersion liquid as a coloring material was prepared.

  Using the color material (cyan dispersion) obtained above, the ink was prepared so as to have the following ink composition (Table 3), and after the preparation, coarse particles were removed with a 5 μm filter, and ink C1-1 was used. It was adjusted. As a result of measuring the physical properties of the obtained ink C1-1, the pH was 9.0, the surface tension was 32.9 mN / m, and the viscosity was 3.9 mPa · s.

  Similarly, Magenta, Yellow, and Black inks were prepared.

iv. Addition polymer Particles such as polymer resin are appropriately added to the above-mentioned treatment liquid and ink. It is preferable to add 1 to 8% of particles having a particle size of 1 μm or less, a minimum film forming temperature of 28 to 50 ° C., and a glass transition point of 40 to 80 ° C. for gloss adjustment in the treatment liquid and for fixing an image in the ink. .

  In addition, adjustment and prescription of each liquid mentioned above are an example to the last, and can be changed suitably.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet printer, 14 ... Paper, 22 ... Paper feed part, 24 ... Penetration suppression agent provision part, 26 ... Treatment liquid provision part, 28 ... Drawing part, 30 ... Drying part, 32 ... Fixing part, 34 ... Paper discharge , 36 ... paper feed tray, 37 ... adhesive roller, 38 ... transfer cylinder, 40 ... impression cylinder, 42 ... permeation inhibitor application device, 44 ... paper presser, 46 ... permeation inhibitor drying unit, 48 ... application roller, 85 DESCRIPTION OF SYMBOLS ... Transfer cylinder, 86 ... Impression cylinder, 202 ... Processing liquid application apparatus, 204 ... Processing liquid drying unit, 210 ... Ink head, 214 ... Transfer cylinder, 216 ... Impression cylinder, 304 ... Transfer cylinder, 306 ... Impression cylinder, 308 ... Drying unit, 324 ... transfer cylinder, 326 ... pressure cylinder, 328a, 328b, 328c ... fixing roller, 344 ... transfer cylinder, 346 ... discharge tray, 348 ... measuring means, 400 ... system controller, 402 ... communication interface 404, image memory, 406, paper feed control unit, 408, permeation suppression agent application control unit, 410 ... treatment liquid application control unit, 412 ... drawing control unit, 414 ... drying control unit, 416 ... fixing control unit, 418 DESCRIPTION OF REFERENCE SIGNS ...... Discharge control unit 420 ... operation unit 422 display unit 600 processing liquid application device 602 application roller 606 squeegee blade 608 main blade 700, 702 clamper 704 706 pin

Claims (12)

At least a predetermined amount of processing liquid is applied to the image forming area in a predetermined amount with respect to the recording medium in which the image forming area is set with a margin at the rear end in the transport direction, and then the front end of the recording medium is gripped While being held by the means, the recording medium is sucked and held on the circumferential surface of the rotating conveyance body to be rotated and conveyed, and ink is ejected onto the image forming area of the rotating and conveyed recording medium by an ink jet head. In an image forming method for forming an image,
When the processing liquid is applied to the recording medium, a processing liquid having a larger amount than the processing liquid applied to the image forming area is applied to a blank area at the rear end of the recording medium. Image forming method.   2. The image forming method according to claim 1, wherein the amount of the processing liquid applied to the blank area at the rear end of the recording medium is varied according to the thickness or bending rigidity of the recording medium.   The treatment liquid applied to the blank area at the rear end of the recording medium in the conveyance direction is applied in a line parallel to a direction orthogonal to the conveyance direction of the recording medium, and the application amount is reduced at both ends in the conveyance direction. The image forming method according to claim 1 or 2.   The image forming area is set by leaving margins on the leading edge in the transport direction and / or on both sides, and the margin area on the leading edge of the recording medium and / or the margin area on both sides is set in the image forming area. The image forming method according to any one of claims 1 to 3, wherein a treatment liquid having a larger amount than the amount of the treatment liquid to be applied is applied.   5. The image according to claim 1, wherein when an image is formed by ejecting ink onto the image forming area with the inkjet head, the ink is ejected onto the blank area. 5. Forming method.   6. When the recording medium is rotated and conveyed by the rotating conveyance body, the recording medium is rotated and conveyed while holding a blank area at the rear end of the recording medium with a pin. The image forming method described in 1. At least a predetermined amount of processing liquid is applied to the image forming area in a predetermined amount with respect to a recording medium in which an image forming area is set with a margin at the rear end in the transport direction, and then a margin at the front end of the recording medium. While gripping the area with the gripping means, the recording medium is sucked and held on the peripheral surface of the rotating conveyance body and is rotated and conveyed, and ink is applied to the image forming area of the rotating and conveying recording medium by an inkjet head. In an image forming apparatus that forms an image by dropping,
The processing liquid applying means uniformly applies a predetermined processing liquid at a predetermined liquid amount to at least the image forming area, and has a liquid amount set larger than a liquid amount of the processing liquid applied to the image forming area. An image forming apparatus, wherein a treatment liquid is applied to a blank area at a rear end of the recording medium.   A setting unit configured to set a liquid amount of a processing liquid to be applied to a blank area at a rear end in the conveyance direction of the recording medium, and the setting unit is arranged in the conveyance direction of the recording medium according to the thickness or bending rigidity of the recording medium. 8. The image forming apparatus according to claim 7, wherein the amount of the processing liquid applied to the margin area at the end is set to be variable.   The treatment liquid application unit applies the treatment liquid in a line parallel to a direction perpendicular to the conveyance direction of the recording medium to a blank area at the rear end in the conveyance direction of the recording medium, and both ends of the conveyance direction. The image forming apparatus according to claim 7, wherein the applied amount is reduced by the step of claim 7.   The image forming area is set by leaving margins on both the front end and / or both sides in the transport direction, and the processing liquid application unit is configured to provide a margin area at the front end of the recording medium and / or a margin area on both sides. The image forming apparatus according to any one of claims 7 to 9, wherein a treatment liquid having a liquid amount set larger than a liquid amount of the treatment liquid to be applied to the image forming area is applied.   11. The ink jet head according to claim 7, wherein when the ink jet ink is ejected onto the image forming area to form an image, the ink is ejected onto the blank area. Image forming apparatus.   The rotating conveyance body grips a blank area at the front end of the recording medium, and rotates and conveys the blank area at the rear end while penetrating and holding the pin with a pin. The image forming apparatus described in the item.

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