JP2010201713A - Inkjet recording method and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method and inkjet recorder which can prevent a recording medium from floating from a drum during printing and also prevent it from changing its shape after printing. <P>SOLUTION: The inkjet recorder includes: an aqueous solution feeding part 11 for giving water or aqueous solution containing water-soluble organic solvent to the rear surface of the recording medium 22; a drawing part 14 for forming a picture by holding the recording medium 22, to which the water or aqueous solution has been given, by a drawing drum 70, and jetting ink to the surface of the recording medium 22; a second middle conveyance part 26 for conveying the recording medium 22 with the rear surface in the released state by a middle carrier 30; and a drying part 16 for drying the ink by holding the recording medium 22 by a drying drum 76. With the inkjet recording method and the inkjet recorder, the amount of grants of water or aqueous solution is adjusted according to the basis weight of the recording medium 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet recording method and a recording apparatus, and more particularly, to an ink jet recording apparatus and a recording method capable of preventing a recording medium from being lifted and transported from a drum in a drum transport system.

  In recent years, there has been an increasing demand for small copies in the printing industry. In the offset printing method that has been used conventionally, it is necessary to prepare a plate, and this has been an obstacle in terms of time and cost when printing a small number of copies. On the other hand, an electrophotographic method is an example of a print-on-demand printing method that does not create a plate. However, the electrophotographic method has a problem that the running cost is high and the productivity is low.

  As a method for solving the above problems, there is a recording method using an ink jet. The ink jet recording method is less expensive than the electrophotographic method and has high productivity. The ink jet recording method has been widely used as a home printer for personal use as well as an office printer for business use. However, when used for printing, it is required to increase the processing speed and image quality, and to cope with printing paper such as coated paper. On the other hand, due to the recent increase in interest in the environment, it is required to use a water-based ink having a smaller environmental burden than a solvent-based ink containing a VOC or the like and having a large environmental burden even in the ink used in the printing field. .

  A major problem when using water-based ink for printing is the occurrence of curling of printing paper. In printing applications, coated paper for printing is generally used. However, unlike such ink-jet exclusive paper, such paper may cause curl because the ink solvent penetrates into the base paper. In general, in order to achieve high image quality in the ink jet recording method, the distance between the ejection surface of the recording head and the recording medium is set to about 1 mm. For this reason, the paper curls or undulates (cockling) and the belt or drum lifts from the conveyance stage, and the paper comes into contact with the ejection surface of the recording head. There is a concern that the recording head may be damaged, ejection failure may occur due to clogging of the recording head, or a paper jam may occur.

  As a method of reducing curling, a high boiling point solvent in the ink applied to the recording medium is a solvent that does not easily cause curling, and a liquid that penetrates the recording medium is difficult to curl by drying moisture at a high speed after application. A technology that uses only a small amount of water has been devised. This method is effective when printing at a high speed and stacking a large number of printed sheets. However, this method alone requires enormous energy because it must be dried quickly. It was. Therefore, combined use with a method described in the following Patent Documents 1 to 3 in which a liquid such as water is applied to only the entire surface or the back surface of the recording medium separately from the ink has been studied.

Japanese Patent Laid-Open No. 2002-361851 JP 2005-178252 A JP 2007-106511 A

  However, in the recording method using the roller conveyance method described in Patent Documents 1 and 2, there is a concern that paper wrinkles may occur when a wet recording medium is conveyed at high speed. Moreover, in the conveyance method using the suction belt described in Patent Document 3, the moisture applied to the back surface is stacked on the stacker without being dried, so that there is a problem that the curl is further increased.

  The present invention has been made in view of such circumstances, and in a drum transport type ink jet recording apparatus, an ink jet recording method capable of preventing the recording medium from floating from the drum and preventing a change in the shape of the recording medium, and An object is to provide a recording apparatus.

  In order to achieve the above object, claim 1 of the present invention draws an aqueous solution applying step for applying an aqueous solution containing water or a water-soluble organic solvent to the back surface of the recording medium, and a recording medium to which the water or the aqueous solution is applied. An ink discharge step of forming an image by ejecting ink onto the surface of the recording medium by being held by a drum-shaped member, and a transporting step of transporting by an intermediate transport body with the back surface of the recording medium being opened. And a drying step of drying the ink by holding the recording medium with a drum-shaped member for drying, and adjusting the application amount of the water or the aqueous solution according to the basis weight of the recording medium An ink jet recording method is provided.

  According to the first aspect, since the back surface of the recording medium is provided with water or an aqueous solution containing a water-soluble organic solvent, the recording medium can be softened and easily bent. Further, since the amount of water necessary for preventing the trailing edge of the recording medium being conveyed from jumping up is given according to the basis weight of the recording medium, when the drum-shaped member holds the recording medium, the recording medium is removed from the drum-shaped member. Transport without floating. Therefore, it is possible to prevent the ejection surface of the ink ejection means from coming into contact with the recording medium, and it is possible to prevent the printing surface from becoming dirty, the ejection surface from being damaged, and ejection failure.

  Further, when transporting from the ink ejection process to the drying process, transport is performed with the back surface of the recording medium being opened by the intermediate transport body. Therefore, in the present invention, water or an aqueous solution is applied to the back surface, but unlike the belt conveyance and roll conveyance, the back surface of the recording medium can be dried, so that curling can be suppressed. Further, when the ink is dried, the curling can be suppressed because the ink is dried while being held by the drum-shaped member.

  A second aspect of the present invention is the first aspect of the present invention, in which the amount of application of the water or the aqueous solution is increased when the basis weight of the recording medium is large, and the amount of application of the water or the aqueous solution is increased when the basis weight of the recording medium is small. Featuring less.

  According to the second aspect, when the basis weight of the recording medium is large, the amount of water or aqueous solution applied can be increased so that the drum-shaped member can be tightly wound and held in each step. When the basis weight is small, it is easy to wind the recording medium around the drum-shaped member. However, if the applied amount is large, cockling or curling occurs, so it is preferable to reduce the applied amount, and it is set appropriately according to the basis weight. It is preferable.

A third aspect is characterized in that, in the first or second aspect, the application amount of the water or the aqueous solution is 0.1 g / m ² or more.

A fourth aspect of the present invention is the method according to any one of the first to third aspects, wherein when the basis weight of the recording medium is 200 g / m ² or less, the basis weight of the recording medium is 10 g / m. ² per, 0.1 g / ^{m 2} or more 0.25 g / ^{m 2} or less, when the basis weight of the recording medium exceeds 200 g / ^{m 2,} a basis weight 10 g / ^{m 2} per the recording medium, 0.24 g / M ² or more and 5.0 g / m ² or less.

  Claims 3 and 4 define the application amount of water or an aqueous solution. By setting the application amount within the above range, the recording medium can be prevented from being lifted from the drum-like member during conveyance. And cockling can be prevented.

  A fifth aspect of the present invention provides the method according to any one of the first to fourth aspects, wherein the water or the aqueous solution is applied to an end portion of the recording medium.

  According to the fifth aspect, by applying water or an aqueous solution to the end portion of the recording medium, the recording medium can be easily bent, and each process can be performed in contact with the drum-shaped member.

  A sixth aspect of the present invention according to any one of the first to fifth aspects, wherein the drum-shaped member and the intermediate conveyance body include a holding unit, and a leading end is held by the holding unit with respect to a conveyance direction of the recording medium, and a rear end A part is provided with the water or the aqueous solution more than the front end part and conveyed.

  According to the sixth aspect of the present invention, the drum-shaped member and the intermediate conveyance body are provided with holding means, and the leading end of the recording medium is held by the holding means to prevent the recording medium from being lifted. Further, since the rear end portion of the recording medium can be held in close contact with the drum-shaped member or the intermediate conveyance body by increasing the application amount of water or aqueous solution, the recording medium can be prevented from being lifted.

  A seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, the water or the aqueous solution is applied by roller coating.

  An eighth aspect is characterized in that the water or the aqueous solution is applied by spraying in any one of the first to sixth aspects.

  Claims 7 and 8 define a method of applying water or an aqueous solution, and are preferable because they can be applied to the back surface of the recording medium in a desired range by applying by roller application or spraying.

  A ninth aspect is characterized in that, in any one of the first to eighth aspects, the water-soluble organic solvent has an SP value of 30 or less.

  According to the ninth aspect, since the SP value of the water-soluble organic solvent contained in the aqueous solution is 30 or less, the occurrence of curling of the recording medium can be suppressed.

  According to a tenth aspect of the present invention, in order to achieve the above object, an aqueous solution applying means for applying an aqueous solution containing water or a water-soluble organic solvent to the back surface of the recording medium, ink droplets are ejected onto the surface of the recording medium, and an image is obtained. An ink discharge means for forming the recording medium, a drawing drum-like member disposed opposite to the ink discharge means for holding and transporting the recording medium, and a drying means for drying the ink applied on the recording medium And a drying drum member that holds and conveys the recording medium disposed opposite to the drying means, and a state in which the back surface of the recording medium is opened from the drawing drum member to the drying drum member Control for adjusting the application amount of the water or the aqueous solution according to the basis weight acquired by the basis weight acquired by the basis weight acquisition means, the basis weight acquisition means for acquiring the basis weight of the recording medium means , To provide an ink jet recording apparatus comprising: a.

  An eleventh aspect of the present invention is the control device according to the tenth aspect, wherein the control unit increases the application amount of the water or the aqueous solution when the basis weight of the recording medium is large, and the water or the when the basis weight of the recording medium is small. It is characterized by controlling the application amount of the aqueous solution to be small.

  A twelfth aspect according to the tenth or eleventh aspect, wherein the drum-shaped member and the intermediate conveyance body include a holding unit that holds a leading end of the recording medium in a conveyance direction, and the aqueous solution supply unit The rear end portion is provided with more water or aqueous solution than the front end portion.

  A thirteenth aspect of the present invention is characterized in that, in any one of the tenth to twelfth aspects, the aqueous solution application unit is an application unit using a roller.

  A fourteenth aspect is characterized in that, in any one of the tenth to twelfth aspects, the aqueous solution applying means is an applying means by spraying.

  In the tenth to fourteenth aspects, the invention of the ink jet recording method is developed as an ink jet recording apparatus. According to the tenth to fourteenth aspects, effects similar to those of the ink jet recording method can be obtained.

  According to the ink jet recording method and the recording apparatus of the present invention, water or an aqueous solution corresponding to the basis weight of the recording medium is applied to the back surface of the recording medium. The recording medium can be transported while being wound around the drum while preventing the edge from jumping up. Therefore, it is possible to prevent the ejection surface of the ink ejection means from coming into contact with the recording medium, thereby preventing a drawing defect. In addition, since the back surface is opened by the intermediate conveyance body between the steps, the back surface can be dried, so that deformation of the recording medium such as curling can be suppressed.

1 is a schematic configuration diagram of an ink jet recording apparatus according to the present invention. It is a schematic block diagram of an aqueous solution supply part. It is a schematic block diagram which shows the other structure of aqueous solution supply part. It is a principal part perspective drawing which shows the internal structure of a head. It is a top view which shows the other structural example of a head. It is sectional drawing which follows the XX line in FIG. It is a top view which shows the nozzle arrangement example of a head. It is a principal block diagram showing the system configuration of the ink jet recording apparatus. 6 is a table showing the results of Test Example 1. FIG. 10 is a table showing the results of Test Example 2. FIG. 10 is a table showing the results of Test Example 3. FIG. 10 is a table showing the results of Test Example 4. FIG. It is a graph which shows the relationship between the basic weight of the printing paper of the test example 5, and the application amount of aqueous solution.

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

[Overall configuration of inkjet recording apparatus]
First, the overall configuration of an ink jet recording apparatus to which the present invention is applied will be described.

  FIG. 1 is a configuration diagram schematically showing an ink jet recording apparatus 1 of the present embodiment. The ink jet recording apparatus 1 shown in FIG. 1 is an apparatus that forms an image on a recording surface of a recording medium 22, and mainly includes a paper feeding unit 10, an aqueous solution supply unit 11, a treatment liquid application unit 12, a drawing unit 14, a drying unit 16, and a fixing unit. It comprises a part 18 and a discharge part 20. A recording medium 22 (sheets) is stacked on the paper supply unit 10. The recording medium 22 is sent from the paper supply unit 10 to the aqueous solution supply unit 11, and water or an aqueous solution is applied to the back surface of the recording medium 22. The The recording medium 22 is then sent to the treatment liquid application unit 12, and after the treatment liquid is applied to the recording surface by the treatment liquid application unit 12, ink is applied to the recording surface by the drawing unit 14. The recording medium 22 to which ink is applied is transported by the discharge unit 20 after the image is fastened by the fixing unit 18.

  Intermediate conveyance units 24, 26, and 28 are provided between the units, and the recording medium 22 is transferred by the intermediate conveyance units 24, 26, and 28. That is, a first intermediate transport unit 24 is provided between the processing liquid application unit 12 and the drawing unit 14, and the recording medium from the processing liquid application unit 12 to the drawing unit 14 by the first intermediate transport unit 24. 22 delivery is performed. Similarly, a second intermediate transport unit 26 is provided between the drawing unit 14 and the drying unit 16. The recording medium 22 is transferred from the drawing unit 14 to the drying unit 16 by the second intermediate transport unit 26. Is done. Further, a third intermediate transport unit 28 is provided between the drying unit 16 and the fixing unit 18, and the third intermediate transport unit 28 transfers the recording medium 22 from the drying unit 16 to the fixing unit 18. Done. When the recording medium 22 is transported by the intermediate transport sections 24, 26, and 28, the back surface (the surface that is not printed) of the recording medium 22 is opened. Thereby, since the drying of the water or aqueous solution applied to the back surface proceeds, the recording medium can be sufficiently dried, and curling can be suppressed.

  Hereinafter, each part of the inkjet recording apparatus 1 (the paper feeding unit 10, the aqueous solution supply unit 11, the treatment liquid application unit 12, the drawing unit 14, the drying unit 16, the fixing unit 18, the discharge unit 20, the first to third intermediate conveyance units) 24, 26, and 28) will be described.

(Paper Feeder)
The paper feed unit 10 is a mechanism that supplies the recording medium 22 to the drawing unit 14. The paper feed unit 10 is provided with a paper feed tray 50, and the recording medium 22 is fed from the paper feed tray 50 to the processing liquid application unit 12 one by one.

(Aqueous solution supply unit)
The aqueous solution supply unit 11 is a mechanism that applies an aqueous solution containing water or a water-soluble organic solvent to the side opposite to the recording surface of the recording medium 22. As the water-soluble organic solvent contained in the aqueous solution, the solvents described later can be used.

  Examples of the application method of the aqueous solution include application by a roller and application by spraying. For example, FIG. 2 shows an enlarged view of the aqueous solution supply unit 11 of the ink jet recording apparatus of FIG. The aqueous solution supply unit 11 shown in FIG. 2 includes an aqueous solution roller 53, an aqueous solution container 55, and the like as application by a roller. The aqueous solution applying device 51 applies the aqueous solution to the back side of the recording medium 22 by rotating and driving an aqueous solution roller 53 partially immersed in the aqueous solution in the aqueous solution container 55 at a constant speed.

  As in the present invention, when drum transport ink jet is used, if thick paper is used as the recording medium, there is a concern that the trailing edge of the recording medium jumps up. In particular, when such jumping occurs on the printing side where the ink jet head is installed, there is a possibility of rubbing the nozzle surface of the ink jet head, which may cause poor drawing. In the present invention, the back surface is provided with water or an aqueous solution containing a water-soluble organic solvent, so that the recording medium can be softened and bent easily, and such jumping can be suppressed. However, conversely, if the applied amount of water or an aqueous solution containing a water-soluble organic solvent is too large, curling may occur due to penetration from the back surface. Therefore, it is necessary to adjust the amount of water or aqueous solution to be applied depending on the basis weight of the recording medium 22, and a larger amount of water or aqueous solution is applied to the thick paper that is likely to jump, and a smaller amount of water or aqueous solution is applied to the thin paper.

Specifically, the application amount of water or an aqueous solution is preferably 0.1 g / m ² or more, more preferably 0.5 g / m ² or more, and further preferably 1.0 g / m ² or more. is there. Further, the 0.01~5.0g / ^{m 2} in each additional 10 g / ^{m 2} basis weight that is preferably increased application amount of water or an aqueous solution, of 0.01 to 1.0 g / ^{m 2} water or an aqueous solution it is more preferable to increase the application amount, it is more preferable to increase the application amount of water or an aqueous solution of 0.05 to 0.5 g / ^{m 2,} the application amount of water or an aqueous solution of 0.1 to 0.3 g / ^{m 2} More preferably, Further, as described above, it is preferable to apply a larger amount of water or an aqueous solution to thick paper, and a smaller amount of water or aqueous solution to thin paper. When the basis weight of the recording medium is 200 g / m ² or less, the basis weight of the recording medium is 10 g / m ^2. m ² per is preferably 0.1 g / ^{m 2} or more 0.25 g / ^{m 2} or less. Further, when the basis weight of the recording medium exceeds 200 g / ^{m 2,} the basis weight of 10 g / ^{m 2} per recording medium, is preferably 0.24 g / ^{m 2} or more 5.0 g / ^{m 2} or less.

  When it is desired to reduce the amount of water or aqueous solution applied, each step can be performed in a state where the recording medium is in contact with the drum-shaped member by applying only to the end of the recording medium. Further, it is preferable to apply a large amount of water or aqueous solution to the rear end side with respect to the conveyance direction of the recording medium. As will be described later, the drum in each step is provided with holding means so that the leading end of the recording medium can be held. Therefore, the jumping of the recording medium is likely to occur on the rear end side with respect to the transport direction, so by increasing the application amount on the rear end side of the recording medium, the trailing end can be prevented from jumping up, and Since the amount applied to the front end of the recording medium can also be reduced, the amount of water or aqueous solution applied can be reduced as a whole. In the case where a large amount is applied to the rear end, it is not particularly limited as long as the trailing end of the recording medium can be prevented from jumping up, and it is preferable to adjust appropriately.

  The method of applying water or an aqueous solution is not limited to the method shown in FIGS. 1 and 2, and may be applied by the aqueous solution supply unit 11 ′ shown in FIG. 3 as another mode. The aqueous solution supply unit 11 ′ is an aqueous solution applying device 51 ′ that applies an aqueous solution by spraying, and FIG. 3 shows a method of applying by an aqueous solution inkjet nozzle. The discharge port of the aqueous solution inkjet nozzle 57 is elongated so as to cover the entire width of the recording medium 22, does not require a scanning operation, is stationary, and the recording medium 22 only passes through the surface facing the discharge port 59. It can be sprayed on the entire surface. Inside the aqueous solution inkjet nozzle 57, there is a common flow path 61, as in the inkjet head, and communicates with an aqueous solution tank (not shown) serving as an aqueous solution supply source. The aqueous solution supplied from the aqueous solution tank can be applied to the recording medium 22 by spraying water or the aqueous solution 63 through the common flow path 110.

  1 to 3, the aqueous solution supply unit 11 is provided next to the paper supply unit 10, but it is sufficient that the recording medium 22 can be wound around the drawing drum 70 in the drawing unit 14. The aqueous solution applying device 51 can be provided at a position facing the intermediate conveyance body 30 between 70. By providing the aqueous solution applying device 51 at a position facing the intermediate carrier 30, it is possible to suppress drying of the water or the aqueous solution due to the drying of the treatment liquid applying unit.

(Processing liquid application part)
The processing liquid application unit 12 is a mechanism for applying a processing liquid to the recording surface of the recording medium 22, and the processing liquid contains a component that aggregates or thickens a coloring material in ink described later. Specific methods for agglomerating or thickening the color material include a treatment liquid that reacts with the ink to precipitate or insolubilize the color material in the ink, and a semi-solid substance (gel) containing the color material in the ink. And the like. The means for causing the reaction between the ink and the treatment liquid is a method of reacting the anionic coloring material in the ink and the cationic compound in the treatment liquid, or by mixing the ink and the treatment liquid having different pHs with each other. A method of agglomerating the pigment by causing dispersion destruction of the pigment in the ink by changing the pH of the ink, a method of causing the dispersion destruction of the pigment in the ink by reaction with the polyvalent metal salt in the treatment liquid, and the like. is there. A more detailed description of the treatment liquid will be described later.

  Examples of the treatment liquid application method include droplet ejection using an inkjet head, application using a roller, and uniform application using a spray. For example, the treatment liquid application unit 12 illustrated in FIG. 1 includes a transfer drum 52, a treatment liquid drum 54, a treatment liquid application device 56, a hot air blowing nozzle 58, and an IR heater 60. The transfer drum 52 is disposed between the paper feed tray 50 and the processing liquid drum 54 of the paper feed unit 10 and is driven to rotate. The recording medium 22 fed from the paper feed unit 10 is received by the transfer drum 52 and transferred to the processing liquid drum 54. In addition, instead of the transfer drum 52, an intermediate conveyance unit described later may be provided.

  The treatment liquid drum 54 is a drum that holds and rotates the recording medium 22 and is driven to rotate. Further, the treatment liquid drum 54 is provided with a gripper 69 which is a claw-shaped holding means on the outer peripheral surface thereof, and the front end of the recording medium 22 can be held by this holding means. The recording medium 22 is rotated and conveyed by rotating the processing liquid drum 54 with the tip held by the holding means. At that time, the recording medium 22 is conveyed so that the recording surface faces outward. Note that suction holes may be provided on the outer peripheral surface of the treatment liquid drum 54, and suction may be performed from the suction holes. As a result, the recording medium 22 can be held in close contact with the peripheral surface of the treatment liquid drum 54.

  The configuration of the processing liquid coating apparatus 56 is not particularly limited. For example, the processing liquid container in which the processing liquid is stored, an anix roller partially immersed in the processing liquid in the processing liquid container, and anix The squeegee is in contact with the roller and performs measurement, and an anix roller and a rubber roller that is pressed against the recording medium 22 on the processing liquid drum 54 and transfers the measured processing liquid to the recording medium 22. According to the processing liquid application device 56, the processing liquid can be applied to the recording medium 22 while being measured with a squeegee. The film thickness of the treatment liquid is desirably sufficiently smaller than the droplet diameter of ink ejected from the ink jet heads 72M, 72C, 72Y, 72K of the drawing unit 14. For example, when the ink droplet ejection amount is 2 pl, the average droplet diameter is 15.6 μm. At this time, when the film thickness of the processing liquid is large, the ink dots float in the processing liquid without contacting the surface of the recording medium 22. Therefore, in order to obtain a landing dot diameter of 30 μm or more when the ink droplet ejection amount is 2 pl, it is desirable that the film thickness of the treatment liquid is 3 μm or less.

The recording medium 22 coated with the treatment liquid by the treatment liquid application device 56 is conveyed to the position of the hot air blowing nozzle 58 and the IR heater 60. The hot air blowing nozzle 58 is configured to blow high temperature (for example, 70 ° C.) warm air toward the recording medium 22 at a constant air volume (for example, 9 m ³ / min), and the IR heater 60 has a high temperature (for example, 180 ° C.). Be controlled. The solvent component of the processing liquid is dried by heating with the hot air blowing nozzle 58 and the IR heater 60. As described above, by drying the treatment liquid applied to the recording medium 22 before the ink is ejected, the ink coloring material can be prevented from floating in the treatment liquid. It is not always necessary to completely evaporate the solvent of the treatment liquid, and the total film thickness after drying (the total of non-drying components [flocculating agent, etc.] in the treatment liquid and the dry residual liquid) is about 1 What is necessary is just to dry so that it may become a thickness of 0.0 g / m < ² > or less.

  In this embodiment, the treatment liquid is applied and dried after water or an aqueous solution is applied to the back surface of the recording medium 22. However, in the drying of the treatment liquid, the back surface of the recording medium 22 is the treatment liquid drum. It is located on the 54 side and is difficult to dry by drying of the treatment liquid, and is not sufficiently dried. Moreover, it is preferable to dry the treatment liquid to such an extent that the water or aqueous solution applied to the back surface cannot be completely dried.

(Drawing part)
The drawing unit 14 is a mechanism for drawing an image corresponding to an input image by ejecting ink using an inkjet method. The drawing unit 70 and an inkjet arranged close to a position facing the outer peripheral surface of the drawing drum 70. The heads 72M, 72C, 72Y, and 72K are configured. The inkjet heads 72M, 72C, 72Y, and 72K correspond to inks of four colors, magenta (M), cyan (C), yellow (Y), and black (K), respectively, and are upstream in the rotation direction of the drawing drum 70. Arranged in order from the side.

  The drawing drum 70 is a drum that holds the recording medium 22 on its outer peripheral surface and rotates and conveys the recording medium 22 and is driven to rotate. In addition, the drawing drum 70 includes a gripper 71 as a claw-shaped holding unit on the outer peripheral surface thereof, and the leading end of the recording medium 22 can be held by the holding unit. The recording medium 22 is rotated and conveyed by rotating the drawing drum 70 with the tip held by the holding means. At that time, the recording medium 22 is conveyed so that the recording surface faces outward, and ink is applied to the recording surface from the ink jet heads 72M, 72C, 72Y, 72K.

  The inkjet heads 72M, 72C, 72Y, and 72K are full-line inkjet recording heads (inkjet heads) each having a length corresponding to the maximum width of the image forming area on the recording medium 22, and the ink ejection surfaces thereof are arranged on the ink ejection surface. Is formed with a nozzle row in which a plurality of nozzles for ink ejection are arranged over the entire width of the image forming area. Each inkjet head 72M, 72C, 72Y, 72K is fixedly installed so as to extend in a direction orthogonal to the conveyance direction of the recording medium 22 (the rotation direction of the drawing drum 70). A corresponding color ink cassette is attached to each of the inkjet heads 72M, 72C, 72Y, 72K.

  From the respective ink jet heads 72M, 72C, 72Y, 72K configured as described above, ink droplets are ejected toward the recording surface of the recording medium 22 held on the outer peripheral surface of the drawing drum 70. As a result, the ink comes into contact with the processing liquid on the processing liquid application unit 12, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. Thereby, the color material flow on the recording medium 22 is prevented, and an image is formed on the recording surface of the recording medium 22. At that time, since the drawing drum 70 of the drawing unit 14 is structurally separated from the processing liquid drum 54 of the processing liquid applying unit 12, the processing liquid may adhere to the ink jet heads 72M, 72C, 72Y, 72K. In addition, the cause of ink ejection failure can be reduced. When a non-ejection nozzle is generated, it is possible to perform a process of making the non-ejection non-ejection unevenness difficult to see by increasing the droplet ejection amount at the nozzle adjacent to the non-ejection nozzle.

  The droplet ejection timing of each of the inkjet heads 72M, 72C, 72Y, and 72K is synchronized with an encoder that detects the rotational speed disposed on the drawing drum 70. Thereby, the landing position can be determined with high accuracy. In addition, the fluctuation of the speed due to the deflection of the drawing drum 70 is learned in advance, and the droplet ejection timing obtained by the encoder 91 is corrected to obtain the deflection of the drawing drum 70, the accuracy of the rotation axis, and the speed of the outer peripheral surface of the drawing drum 70. Irregular droplet ejection can be reduced without depending on it.

  In addition, maintenance operations such as cleaning the nozzle surfaces of each of the inkjet heads 72M, 72C, 72Y, and 72K and discharging the thickened ink may be performed by retracting the head unit from the drawing drum 70.

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

(Drying part)
The drying unit 16 is a step of drying the solvent separated by the color material aggregating action, and includes a drying drum 76, a first IR heater 78 disposed at a position facing the outer peripheral surface of the drying drum 76, and hot air. The jet nozzle 80 and the second IR heater 82 are used. The first IR heater 78 is provided upstream of the hot air jet nozzle 80 in the rotation direction of the drying drum 76 (counterclockwise direction in FIG. 1), and the second IR heater 82 is jetted of hot air. Provided downstream of the nozzle 80.

  The drying drum 76 is a drum that holds the recording medium 22 on its outer peripheral surface and rotates and conveys the recording medium 22 and is driven to rotate. Further, the drying drum 76 includes a gripper 77 which is a claw-shaped holding unit on the outer peripheral surface thereof, and the leading end of the recording medium 22 can be held by the holding unit. The recording medium 22 is rotated and conveyed by rotating the drying drum 76 with the tip held by the holding means. At that time, the recording surface of the recording medium 22 is conveyed so that the recording surface 22 faces outward, and a drying process is performed on the recording surface by the first IR heater 78, the hot air jet nozzle 80, and the second IR heater 82. Is called.

The hot air jet nozzle 80 is configured to blow hot air controlled to a predetermined temperature (for example, 50 ° C. to 70 ° C.) toward the recording medium 22 at a constant air volume (12 m ³ / min). The IR heater 78 and the second IR heater 82 are each controlled to a predetermined temperature (for example, 180 ° C.).

By the first IR heater 78, the hot air jet nozzle 80, and the second IR heater 82, water contained in the ink solvent on the recording surface of the recording medium 22 held on the drying drum 76 is evaporated, and a drying process is performed. Is done. The residual water amount of the ink-derived water after the drying treatment is preferably 1 g / m ² or more and 4 g / m ² or less.

  During the drying process, the drying drum 76 of the drying unit 16 is structurally separated from the drawing drum 70 of the drawing unit 14, so that the head meniscus portion of the ink jet heads 72M, 72C, 72Y, and 72K is thermally dried. Ink ejection failure due to drying can be reduced. Moreover, there is a degree of freedom in setting the temperature of the drying unit 16, and an optimal drying temperature can be set.

  It is preferable to control the temperature so as to satisfy the relationship of Td <Tp, where Td is the temperature reached on the image surface in the drying step and Tp is the softening point of the self-dispersing polymer fine particles of the ink. By controlling Td <Tp, it is possible to prevent the dot diameter from being reduced and to prevent the occurrence of image curvature (the state in which the image is curved in a curved shape). Decrease in rubbing and image gloss can be prevented. Here, the softening temperature Tp of the self-dispersing polymer fine particles is preferably 30 ° C. or higher and 70 ° C. or lower. This is because when Tp is less than 30 ° C., offset due to insufficient drying occurs, and when Tp exceeds 70 ° C., the film property is insufficient under high-speed recording.

  The evaporated water may be discharged out of the apparatus together with air by a discharge means (not shown). Further, the recovered air may be cooled by a cooler (radiator) or the like and recovered as a liquid.

  Further, the drying drum 76 is preferably controlled at a predetermined temperature (for example, 60 ° C. or lower) on the outer peripheral surface thereof.

  Further, the drying drum 76 may be provided with suction holes on the outer peripheral surface thereof and connected to suction means for performing suction from the suction holes. As a result, the recording medium 22 can be held in close contact with the peripheral surface of the drying drum 76.

(Fixing part)
If necessary, after drying by the drying unit, the resin contained in the ink is melted by heat and pressure contact using a fixing roller at the fixing unit, thereby obtaining image fixability and flattening the dots. Can do.

  The fixing unit 18 includes a fixing drum 84, a first fixing roller 86, a second fixing roller 88, and an inline sensor 90. The first fixing roller 86, the second fixing roller 88, and the inline sensor 90 are disposed at a position facing the peripheral surface of the fixing drum 84, and are sequentially disposed from the upstream side in the rotation direction of the fixing drum 84.

  The fixing drum 84 is a drum that rotates and conveys the recording medium 22 while holding the recording medium 22 on the outer peripheral surface thereof, and is driven to rotate. Further, the fixing drum 84 includes a gripper 85 as a claw-shaped holding unit on the outer peripheral surface thereof, and the leading end of the recording medium 22 can be held by the holding unit. The recording medium 22 is rotated and conveyed by rotating the fixing drum 84 with the tip held by the holding means. At that time, the recording surface of the recording medium 22 is conveyed so that it faces outward, and the recording surface is subjected to fixing processing by the first fixing roller 86 and the second fixing roller 88 and inspection by the inline sensor 90. Done.

  The first fixing roller 86 and the second fixing roller 88 are roller members for welding the self-dispersing polymer fine particles in the ink by heating and pressurizing the dried ink to form a film of the ink. The medium 22 is configured to be pressurized and heated. Specifically, the first fixing roller 86 and the second fixing roller 88 (each heated to, for example, about 80 ° C.) are brought into pressure contact with the fixing drum 84 at a predetermined pressure (for example, 0.3 MPa). And a nip roller with the fixing drum 84. As a result, the recording medium 22 is sandwiched between the first fixing roller 86 and the fixing drum 84 and between the second fixing roller 88 and the fixing drum 84, and a predetermined nip pressure (for example, 0.3 MPa). ) And the fixing process is performed.

  Note that an elastic layer may be formed on one surface of the first fixing roller 86, the second fixing roller 88, and the fixing drum 84 to have a uniform nip width with respect to the recording medium 22. For example, the surface of the first fixing roller 86 and the surface of the second fixing roller 88 have a two-layer structure, and the first layer on the surface layer side is formed of a releasable material, and the second layer (inner layer). Is preferably made of a rubber elastic material. By using the first layer as a releasable material, the roller is less likely to become dirty, and the cleaning load on the roller can be reduced. The second layer is preferably a rubber elastic body having a rubber hardness of 50 ° or less. By making the second layer a rubber elastic body having a hardness of 50 ° or less, it is possible to gain time for nipping the recording medium 22, which is advantageous for forming a film in high-speed recording. Further, by setting the second layer to a hardness of 50 ° or less, it is possible to reduce the pressure when contacting the recording medium 22, and the life of the roller can be improved. On the other hand, the roller surface hardness of the first fixing roller 86 and the second fixing roller 88 is preferably 70 ° or less. By reducing the surface hardness of the roller, the followability to image irregularities (in a certain time) is improved, which is advantageous for coating at high speed recording.

  The first fixing roller 86 and the second fixing roller 88 are constituted by a heating roller in which a halogen lamp is incorporated in a metal pipe such as aluminum having good heat conductivity, and have a predetermined temperature (for example, 60 to 80 ° C.). To be controlled. In this case, when the arrival temperature on the image surface is Tf, it is preferably set so as to satisfy the relationship of Tp <Tf with respect to the softening point Tp of the self-dispersing polymer fine particles of the ink.

  When the recording medium 22 is pressurized and heated by the first fixing roller 86 and the second fixing roller 88 configured as described above, thermal energy equal to or higher than the Tg temperature (glass transition temperature) of the latex contained in the ink. Is applied and the latex particles are melted. As a result, pressing and fixing are performed on the unevenness of the recording medium 22, and the unevenness on the surface of the image is leveled to obtain glossiness.

  In the above-described embodiment, an example in which both heating and pressurization are performed is shown, but only one may be performed. Further, the first fixing roller 86 and the second fixing roller 88 may be provided in a plurality of stages depending on the thickness of the image layer and the Tg characteristics of the latex particles. Further, the surface of the fixing drum 84 may be controlled to a predetermined temperature (for example, 60 ° C.).

  On the other hand, the in-line sensor 90 is a measuring unit for measuring a check pattern, a moisture content, a surface temperature, a glossiness, and the like for an image fixed on the recording medium 22, and a CCD line sensor or the like is applied.

  According to the fixing unit 18 configured as described above, latex particles in the thin image layer formed by the drying unit 16 are pressed and heated by the first fixing roller 86 and the second fixing roller 88. Since it is melted, it can be fixed and fixed on the recording medium 22. Further, according to the fixing unit 18, the fixing drum 84 is structurally separated from the other drums. Therefore, the temperature setting of the fixing unit 18 can be freely set separately from the drawing unit 14 and the drying unit 16. be able to.

  The fixing drum 84 may be provided with a suction hole on the outer peripheral surface thereof and connected to a suction unit that performs suction from the suction hole. As a result, the recording medium 22 can be held in close contact with the peripheral surface of the fixing drum 84.

(Discharge part)
As shown in FIG. 1, a discharge unit 20 is provided following the fixing unit 18. The discharge unit 20 includes a discharge tray 92, and a transfer drum 94, a conveyance belt 96, and a tension roller 98 are provided between the discharge tray 92 and the fixing drum 84 of the fixing unit 18 so as to be in contact therewith. It has been. The recording medium 22 is sent to the transport belt 96 by the transfer drum 94 and discharged to the discharge tray 92.

  In the case of performing double-sided printing, after the paper feeding unit to discharging unit are finished, the recording medium is reversed, and similarly, printing on the surface opposite to the printed surface is performed. As a method for performing duplex printing, for example, after printing one side, the recording medium is turned upside down, and the other side is printed through the same apparatus (paper feeding unit to discharge unit). , The paper is flipped over and back to the stack position of the paper, the other side is printed, after printing one side, the user flips the front and back and returns the paper back to the stack position to print the other side It can be performed by the method of doing. In the case of double-sided printing, water or an aqueous solution is applied to the surface on which an image has already been formed. In the formed image, the color material is aggregated by an aggregating agent, and the fixing step Therefore, even if water or an aqueous solution is applied to the surface on which the image is formed, the image can be formed without any particular problem.

(Intermediate transport section)
Next, the structure of the first intermediate transport unit 24 will be described. Note that the second intermediate conveyance unit 26 and the third intermediate conveyance unit 28 have the same configuration as the first intermediate conveyance unit 24, and a description thereof will be omitted.

  The first intermediate transport unit 24 includes an intermediate transport body 30. The intermediate conveyance body 30 is a drum for receiving the recording medium 22 from the preceding drum, rotating and conveying it to the subsequent drum, and is rotatably attached. Further, the intermediate transport body 30 is rotated by a motor (not shown).

  On the outer peripheral surface of the intermediate conveyance body 30, grippers 31 as claw-shaped holding means are provided at intervals of 90 °. The holding unit rotates while drawing a circular locus, and the tip of the recording medium 22 is held by the operation of the holding unit. Accordingly, the recording medium 22 can be rotated and conveyed by rotating the intermediate conveyance body 30 with the holding means holding the tip of the recording medium 22. The recording surface of the recording medium may be conveyed in a non-contact manner by providing a plurality of air outlets on the surface of the intermediate carrier 30 and blowing out air from the air outlets.

  The recording medium 22 transported by the first intermediate transport unit 24 is transferred to the subsequent drum (that is, the drawing drum 70). At this time, the recording medium 22 is delivered by synchronizing the holding means of the intermediate transport unit 24 and the holding means of the drawing unit 14. The transferred recording medium 22 is held and drawn by the drawing drum 70.

  Further, as shown in FIG. 1, when the recording medium 22 is transferred from the processing liquid drum 54 to the intermediate conveyance body 30, the printing surface of the recording medium 22 is intermediately conveyed while being wound around the intermediate conveyance body 30. It contacts the body 30 and the back side is open. In the present invention, water or an aqueous solution is applied before applying the treatment liquid. However, since the back side of the recording medium is opened in the intermediate conveyance unit, the back side can be dried. The drying of the back side of the recording medium can be performed without providing a drying device, but it can also be performed using a hot air jet nozzle, an IR heater, or the like.

(Inkjet head structure)
Next, the structure of each inkjet head will be described. Since the structures of the ink-jet heads 72M, 72C, 72Y, and 72K for each color are the same, the ink-jet head will be denoted by reference numeral 100 as a representative of them.

  4A is a perspective plan view showing an example of the structure of the inkjet head 100, and FIG. 4B is an enlarged view of a part thereof. In order to increase the dot pitch printed on the recording medium 22, it is necessary to increase the nozzle pitch in the inkjet head 100. As shown in FIGS. 4A and 4B, the inkjet head 100 of the present example includes a plurality of ink chamber units (including ink nozzles 102, pressure chambers 104 corresponding to the nozzles 102, and the like). It has a structure in which droplet ejection elements 108 as recording element units are arranged in a zigzag matrix (two-dimensionally), and thereby, in the longitudinal direction of the head (direction perpendicular to the conveyance direction of the recording medium 22). A high density of substantial nozzle intervals (projection nozzle pitch) projected so as to be aligned along the line is achieved.

  One or more nozzle rows are formed over a length corresponding to the entire width of the image forming area of the recording medium 22 in a direction (arrow M in FIG. 4) substantially orthogonal to the conveyance direction of the recording medium 22 (arrow S in FIG. 4). The form is not limited to the illustrated example. For example, instead of the configuration of FIG. 4 (a), as shown in FIG. 5, a long head module 100 ′ in which a plurality of nozzles 102 are two-dimensionally arranged is arranged in a staggered manner and connected to form a long one. Therefore, a line head having a nozzle row having a length corresponding to the entire width of the image forming area of the recording medium 22 as a whole may be configured.

  The pressure chamber 104 provided corresponding to each nozzle 102 has a substantially square planar shape (see FIGS. 4A and 4B), and the nozzle 102 is provided at one of the diagonal corners. An outlet for supplying ink (supply port) 106 is provided on the other side. The shape of the pressure chamber 104 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon, other polygons, a circle, an ellipse, and the like.

  FIG. 6 is a cross-sectional view showing a three-dimensional configuration of a droplet ejection element for one channel (an ink chamber unit corresponding to one nozzle 102) serving as a recording element unit in the inkjet head 100 (X in FIG. 4A). FIG.

  As shown in FIG. 6, each pressure chamber 104 communicates with the common flow path 110 via the supply port 106. The common flow path 110 communicates with an ink tank (not shown) as an ink supply source, and ink supplied from the ink tank is supplied to each pressure chamber 104 via the common flow path 110.

  An actuator 116 having an individual electrode 114 is joined to a pressure plate (vibrating plate also serving as a common electrode) 112 constituting a part of the pressure chamber 104 (the top surface in FIG. 6). By applying a driving voltage between the individual electrode 114 and the common electrode, the actuator 116 is deformed to change the volume of the pressure chamber 104, and ink is ejected from the nozzle 102 due to the pressure change accompanying this. For the actuator 116, a piezoelectric element using a piezoelectric material such as lead zirconate titanate or barium titanate is preferably used. When the displacement of the actuator 116 returns to the original state after ink ejection, new ink is refilled into the pressure chamber 104 from the common flow path 110 through the supply port 106.

  By controlling the driving of the actuator 116 corresponding to each nozzle 102 in accordance with dot data generated by digital halftoning processing from the input image, ink droplets can be ejected from the nozzle 102. A desired image can be recorded on the recording medium 22 by controlling the ink ejection timing of each nozzle 102 in accordance with the conveyance speed while conveying the recording medium 22 in the sub-scanning direction at a constant speed.

  As shown in FIG. 7, the ink chamber unit 108 having the above-described structure is latticed in a fixed arrangement pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape.

  That is, the pitch P of the nozzles projected (orthographically projected) so as to be aligned in the main scanning direction by a structure in which a plurality of ink chamber units 108 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction. D × cos θ, and in the main scanning direction, each nozzle 102 can be handled equivalently as a linear array with a constant pitch P. With such a configuration, it is possible to realize a substantial increase in the density of nozzle rows projected so as to be aligned in the main scanning direction.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and each block is sequentially driven from one side to the other, etc., and one line (by one row of dots) in a direction perpendicular to the conveyance direction of the recording medium 22 Driving a nozzle that prints a line or a line composed of a plurality of rows of dots is defined as main scanning.

  In particular, when driving the nozzles 102 arranged in a matrix as shown in FIG. 7, the main scanning as described in the above (3) is preferable. That is, nozzles 102-11, 102-12, 102-13, 102-14, 102-15, 102-16 are made into one block (other nozzles 102-21,..., 102-26 are made into one block, , 102-36 as one block,...), And the nozzles 102-11, 102-12,. One line is printed in a direction orthogonal to the 22 conveyance direction.

  On the other hand, by moving the full line head and the recording medium 22 relative to each other, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the main scanning described above is repeatedly performed. This is defined as sub-scanning.

  The direction indicated by one line (or the longitudinal direction of the belt-like region) recorded by the main scanning is referred to as a main scanning direction, and the direction in which the sub scanning is performed is referred to as a sub scanning direction. That is, in the present embodiment, the conveyance direction of the recording medium 22 is the sub-scanning direction, and the direction orthogonal to the recording medium 22 is the main scanning direction. In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example.

  In the present embodiment, a method of ejecting ink droplets by deformation of an actuator 116 typified by a piezo element (piezoelectric element) is employed, but the method of ejecting ink is not particularly limited, and is replaced with a piezo jet method. Various systems such as a thermal jet system in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

(Description of control system)
FIG. 8 is a principal block diagram showing the system configuration of the inkjet recording apparatus 1. The inkjet recording apparatus 1 includes a communication interface 120, a system controller 122, a print control unit 124, a treatment liquid application control unit 126, an aqueous solution application control unit 162, a first intermediate conveyance control unit 128, a head driver 130, and a second intermediate conveyance control unit. 132, a drying control unit 134, a third intermediate conveyance control unit 136, a fixing control unit 138, an inline sensor 90, an encoder 91, a motor driver 142, a memory 144, a heater driver 146, an image buffer memory 148, a suction control unit 149, and the like. ing.

  The communication interface 120 is an interface unit that receives image data sent from the host computer 150. As the communication interface 120, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 150 is taken into the inkjet recording apparatus 1 via the communication interface 120 and temporarily stored in the memory 144.

  The system controller 122 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 1 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 122 includes the communication interface 120, the treatment liquid application control unit 126, the aqueous solution application control unit 162, the first intermediate conveyance control unit 128, the head driver 130, the second intermediate conveyance control unit 132, the drying control unit 134, 3 Controls each part such as the intermediate conveyance control unit 136, the fixing control unit 138, the memory 144, the motor driver 142, the heater driver 146, and the suction control unit 149, and controls communication with the host computer 150, read / write control of the memory 144, etc. And a control signal for controlling the motor 152 and the heater 154 of the transport system is generated.

  The memory 144 is a storage unit that temporarily stores an image input via the communication interface 120, and data is read and written through the system controller 122. The memory 144 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The ROM 145 stores programs executed by the CPU of the system controller 122 and various data necessary for control. The ROM 145 may be a non-rewritable storage unit, or may be a rewritable storage unit such as an EEPROM. The memory 144 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 142 is a driver that drives the motor 152 in accordance with an instruction from the system controller 122. In FIG. 8, the motors arranged in the respective units in the apparatus are represented by reference numeral 152. For example, the motor 152 shown in FIG. 8 includes a motor that drives the rotation of the transfer drum 52, the treatment liquid drum 54, the drawing drum 70, the drying drum 76, the fixing drum 84, the transfer drum 94, and the like. A drive motor for the pump 75 for sucking negative pressure from the suction hole, a motor for a retraction mechanism for the head units of the ink jet heads 72M, 72C, 72Y, 72K, and the like are included.

  The heater driver 146 is a driver that drives the heater 154 in accordance with an instruction from the system controller 122. In FIG. 8, a plurality of heaters provided in the ink jet recording apparatus 1 are represented by reference numeral 154 as a representative. For example, the heater 154 shown in FIG. 8 includes a preheater (not shown) for heating the recording medium 22 to an appropriate temperature in the paper supply unit 10 in advance.

  The print control unit 124 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the memory 144 under the control of the system controller 122, and the generated print. It is a control unit that supplies data (dot data) to the head driver 130. Necessary signal processing is performed in the print control unit 124, and the ejection amount and ejection timing of the ink droplets of the inkjet head 100 are controlled via the head driver 130 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 124 includes an image buffer memory 148, and image data, parameters, and other data are temporarily stored in the image buffer memory 148 when image data is processed in the print control unit 124. In FIG. 8, the image buffer memory 148 is shown in a mode associated with the print control unit 124, but can also be used as the memory 144. Also possible is an aspect in which the print control unit 124 and the system controller 122 are integrated to form a single processor.

  An outline of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 120 and stored in the memory 144. At this stage, for example, RGB image data is stored in the memory 144.

  In the ink jet recording apparatus 1, a pseudo continuous tone image is formed by changing the droplet ejection density and dot size of fine dots with ink (coloring material) to the human eye. It is necessary to convert to a dot pattern that reproduces the gradation (shading of the image) as faithfully as possible. Therefore, the original image (RGB) data stored in the memory 144 is sent to the print control unit 124 via the system controller 122, and the print control unit 124 performs halftoning processing using a threshold matrix, an error diffusion method, or the like. Is converted into dot data for each ink color.

  That is, the print control unit 124 performs a process of converting the input RGB image data into dot data of four colors K, C, M, and Y. Thus, the dot data generated by the print control unit 124 is stored in the image buffer memory 148.

  The head driver 130 is a drive signal for driving the actuator 116 corresponding to each nozzle 102 of the inkjet head 100 based on print data (that is, dot data stored in the image buffer memory 148) given from the print control unit 124. Is output. The head driver 130 may include a feedback control system for keeping the head driving condition constant.

  When the drive signal output from the head driver 130 is applied to the inkjet head 100, ink is ejected from the corresponding nozzle 102. An image is formed on the recording medium 22 by controlling the ink ejection from the inkjet head 100 while conveying the recording medium 22 at a predetermined speed.

  In addition, the system controller 122 includes a processing liquid application control unit 126, an aqueous solution application control unit 162, a first intermediate transfer control unit 128, a second intermediate transfer control unit 132, a drying control unit 134, a third intermediate transfer control unit 136, and a fixing. The controller 138 and the suction controller 149 are controlled.

  The treatment liquid application control unit 126 controls the operation of the treatment liquid application device 56 of the treatment liquid application unit 12 in accordance with an instruction from the system controller 122. Specifically, in the treatment liquid application device 56, a rubber roller rotation drive unit 156 that drives rotation of the rubber roller, an anilox roller rotation drive unit 158 that drives rotation of the anilox roller, and a liquid feed pump that supplies the treatment liquid to the treatment liquid container 160 and the like are controlled by the processing liquid application control unit 126.

  The aqueous solution application control unit 162 controls the operation of the aqueous solution application device 51 of the aqueous solution supply unit 11 in accordance with an instruction from the system controller 122. For the basis weight information of the recording medium, the application amount of water or aqueous solution corresponding to the basis weight of the recording medium can be directly input by a personal computer (not shown). Also, the application amount of water or an aqueous solution corresponding to the basis weight of the recording medium is stored in the ROM 145, and the basis weight of the recording medium is input, or a weight measuring machine (not shown) is connected to the paper feeding unit 10. It is possible to determine the amount of water or aqueous solution to be applied from the numerical value from the weighing machine and the data in the ROM 145. The aqueous solution application control unit 162 is controlled by the aqueous solution application control unit 162 in the aqueous solution application device 51, such as an aqueous solution roller rotation driving unit 164 that drives the rotation of the aqueous solution roller, a liquid feed pump 166 that supplies water or an aqueous solution to the aqueous solution container 55, and the like. Is done.

  The first intermediate conveyance control unit 128 controls the operation of the intermediate conveyance body 30 of the first intermediate conveyance unit 24 in accordance with an instruction from the system controller 122. Specifically, in the intermediate transport body 30, the rotational drive of the intermediate transport body 30 itself, the holding means provided in the intermediate transport body 30, and the like are controlled. The second intermediate transfer control unit 132 and the third intermediate transfer control unit 136 also perform the same control as the first intermediate transfer control unit 128.

[recoding media]
In the present invention, by applying water or an aqueous solution to the back surface of the recording medium, the recording medium can be easily bent, adhesion to the drum-shaped member is improved, and the applied amount is set according to the basis weight of the recording medium. Since it is adjusted, any liquid permeable medium can be used without particular limitation, and plain paper, coated paper, and the like can be used. Among these, in the present invention, it is more effective when plain paper is used. When water-based ink is ejected onto plain paper, curling and further curling to the opposite side occur with drying. In the present invention, water or an aqueous solution is applied from the opposite side of the printing surface. Therefore, the printing medium can be wound around the drum and the intermediate conveyance body, so that the recording medium is not conveyed in a state of floating from the drum. Can be used.

[Description of treatment liquid and ink]
As the ink used, a dye ink in which a color material is dissolved in a molecular state (may be in an ionic state) in a liquid solvent, or a pigment ink in which a color material is dispersed in a minute mass in a liquid solvent Etc.

  On the other hand, the treatment liquid is a liquid that generates an aggregate of color materials when mixed with ink. Specifically, a treatment liquid that reacts with ink to precipitate or insolubilize the color material in the ink, a treatment liquid that generates a semi-solid substance (gel) containing the color material in the ink, and the like can be given.

  The means for causing the reaction between the ink and the treatment liquid is a method of reacting the anionic coloring material in the ink and the cationic compound in the treatment liquid, or by mixing the ink and the treatment liquid having different pHs with each other. A method of agglomerating the pigment by causing dispersion destruction of the pigment in the ink by changing the pH of the ink, a method of causing the dispersion destruction of the pigment in the ink by reaction with the polyvalent metal salt in the treatment liquid, and the like. is there.

[Water or aqueous solution containing water-soluble organic solvent]
An aqueous solution containing water or a water-soluble organic solvent is used as a liquid applied to the back surface of the recording medium.

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

  The amount of the water-soluble organic solvent can be arbitrarily used with respect to water, but is preferably 1% to 90%, more preferably 5% to 70%, and particularly preferably 10% to 50%. . Moreover, the water-soluble organic solvent of this invention can also be used in mixture of multiple types.

As the water-soluble organic solvent, it is preferable to use a water-soluble organic solvent having an SP value of 30 or less from the viewpoint of curling reduction. The ratio of the water-soluble organic solvent having an SP value of 30 or less to the total solvent is preferably 1% to 90%, more preferably 5% to 70%, and particularly preferably 10% to 50%. A water-soluble high-boiling organic solvent having an SP value of 30 or less is shown below.
Diethylene glycol monoethyl ether (22.4)
Diethylene glycol monobutyl ether (21.5)
Triethylene glycol monobutyl ether (21.1)
Dipropylene glycol monomethyl ether (21.3)
Dipropylene glycol (27.2)

_{nC 4 H 9 O (AO)} 4 -H (AO = the ratio in EO or PO 1: 1) ( 20.1) EO = ethyleneoxy _{nC 4 H 9 O (AO)} 10 -H ( Id.) (18. 8)
HO (A′O) ₄₀ −H (A′O = EO or PO, the ratio is EO: PO = 1: 3) (18.7)
HO (A'O) ₅₅ -H (A "O = EO or PO, ratio is EO: PO = 5: 6) (18.8)
HO (PO) ₃ H (24.7)
HO (PO) ₇ H (21.2)
1,2 hexanediol (27.4)
The numerical values in parentheses indicate SP values.

  Moreover, it is preferable that the following structure is contained among the solvents with low SP value.

Etc. The SP value (solubility parameter) of the water-soluble high-boiling organic solvent referred to in the present invention is a value represented by the square root of the molecular cohesive energy. F. It can be calculated by the method described in Fedors, Polymer Engineering Science, 14, p147 (1974). The unit is (MPa) ^1/2 and refers to the value at 25 ° C.

  These water-soluble high-boiling organic solvents can be used alone or in combination with water and other organic solvents.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto.

[Material adjustment]
<Cyan ink composition preparation>
(Synthesis of resin dispersant P-1)
Synthesized according to the following scheme. In addition, the number of each structural unit of the compound example (P-1) shown below represents mass ratio. Hereinafter, the same applies to each structural formula.

  To 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. in a nitrogen atmosphere. A solution prepared by dissolving 0.85 g of dimethyl 2,2'-azobisisobutyrate, 60 g of benzyl methacrylate, 10 g of methacrylic acid and 30 g of methyl methacrylate in 50 g of methyl ethyl ketone was added dropwise over 3 hours. After completion of the dropwise addition, the mixture was further reacted for 1 hour, and then a solution obtained by dissolving 0.42 g of dimethyl 2,2'-azobisisobutyrate 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 of hexane, and the precipitated resin was dried to obtain 96 g of a resin dispersant P-1.

The composition of the obtained resin was confirmed by ¹ H-NMR, and the weight average molecular weight (Mw) determined by GPC 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 aqueous dispersion of self-dispersing polymer fine particles (B-01))
To a 2 L three-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 360.0 g of methyl ethyl ketone was charged, and the temperature was raised to 75 ° C. While maintaining the temperature in the reaction vessel at 75 ° C., 180.0 g of phenoxyethyl acrylate, 162.0 g of methyl methacrylate, 18.0 g of acrylic acid, 72 g of methyl ethyl ketone, and “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) A mixed solution consisting of 44 g was added dropwise at a constant speed so that the addition was completed in 2 hours. After completion of the dropwise addition, a solution consisting of 0.72 g of “V-601” and 36.0 g of methyl ethyl ketone was added, stirred for 2 hours at 75 ° C., and then a solution consisting of 0.72 g of “V-601” and 36.0 g of isopropanol was added. After stirring at 75 ° C. for 2 hours, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours. The weight average molecular weight (Mw) of the obtained copolymer was 64000 (calculated in terms of polystyrene by gel permeation chromatography (GPC), columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (manufactured by Tosoh Corporation)), The acid value was 38.9 (mgKOH / g).

  Next, 668.3 g of the polymerization solution was weighed, 388.3 g of isopropanol and 145.7 ml of 1 mol / L NaOH aqueous solution were added, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water. Thereafter, the temperature in the reaction vessel was maintained at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure, and then the reaction vessel was depressurized, and isopropanol, methyl ethyl ketone, and distilled water totaled 913. 7 g was distilled off to obtain an aqueous dispersion (emulsion) of self-dispersing polymer fine particles (B-01) having a solid content concentration of 28.0%.

(Creation of dispersion of cyan pigment-containing resin particles)
Pigment Blue 15: 3 (phthalocyanine blu-A220 manufactured by Dainichi Seika Co., Ltd.), 5 parts by mass of P-1 resin dispersant described in Table 1, 42 parts by mass of methyl ethyl ketone, and 1 N aqueous NaOH solution. 8 parts by mass and 86.9 parts by mass of ion-exchanged water were mixed and dispersed with 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 dispersion of pigment-containing resin particles having a pigment concentration of 10.2% by mass.

(Adjustment of Cyan Ink Composition C-1)
Next, using the obtained dispersion of pigment-containing resin particles and an aqueous dispersion (emulsion) of self-dispersing polymer fine particles (B-01), an ink composition was prepared with the following composition.
-39.2 parts by mass of pigment-containing resin particle dispersion-28.6 parts by mass of water dispersion of self-dispersing polymer fine particles (B-01)-GP-250 (trioxypropylene glyceryl ether,
SANNICS GP250, manufactured by Sanyo Chemical Industries, Ltd.)) 10 parts by mass, DEGmEE (diethylene glycol monoethyl ether) 5 parts by mass, Olphine E1010 (produced by Nissin Chemical Industry Co., Ltd.) 1 part by mass, ion-exchanged water 16.2 Part by mass (adjustment of magenta ink composition M-1)
Magenta as in the preparation of the cyan ink composition except that Pigment Blue 15: 3 was changed to Ciba Specialty Chemicals Cromophtal Jet Magenta DMQ (PR-122) when preparing the dispersion of cyan pigment-containing resin particles. Ink composition M-1 was prepared.

(Adjustment of yellow ink composition Y-1)
The yellow ink composition Y-1 was prepared in the same manner as the cyan ink composition except that Pigment Blue 15: 3 was changed to Irgalite Yellow GS (PY74) of Ciba Specialty Chemicals during the preparation of the cyan pigment dispersion. Created.

(Preparation of black ink composition Bk-1)
A black ink composition Bk-1 was prepared in the same manner as the cyan ink composition except that Pigment Blue 15: 3 was changed to Carbon Black MA100 manufactured by Mitsubishi Chemical Corporation during the preparation of the cyan pigment dispersion.

(Adjustment of aqueous solution)
The aqueous solution applied to the back surface of the recording medium was prepared by mixing materials with the following composition.
GP-250 (trioxypropylene glyceryl ether,
SANNICS GP250, manufactured by Sanyo Chemical Industries, Ltd.) 10 parts by mass / DEGmEE (diethylene glycol monoethyl ether) 5 parts by mass / Olfin E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1 part by mass, 84 parts by mass of ion-exchanged water (Adjustment of processing solution)
The treatment liquid was adjusted by mixing materials with the following composition.
Malonic acid (manufactured by Wako Pure Chemical Industries) 22.5 parts by mass GP250 (trioxypropylene glyceryl ether,
Sanix GP250, manufactured by Sanyo Chemical Industries, Ltd.) 10.0 parts by mass, Olphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 0.01 parts by mass, ion-exchanged water 67.49 parts by mass When measured, the viscosity was 2.3 mPa · s, the surface tension was 42 mN / m, and the pH was 0.9.

[Inkjet recording method]
(Test Example 1)
Using the ink jet recording apparatus shown in FIG. 1 having a piezo ink jet nozzle as the ink jet nozzle, recording on the recording medium 22 was performed using the ink, aqueous solution, and treatment liquid described above. As the recording medium 22, an OK top coat + (manufactured by Oji Paper Co., Ltd.) 104.7 gsm was used. The aqueous solution was applied to the entire back surface of the recording medium 22 using a gravure roller at an applied amount of 2 gsm.

  The treatment liquid was applied and dried on the entire surface of the recording medium, and ejected and ejected from the ink jet head at the drawing section. The piezo ink jet head was driven so that 2-8 pl multi-size dots could be ejected at a resolution of 1200 × 1200 dpi. In the present invention, dpi represents the number of dots per 2.54 cm. A 200 mm × 200 mm solid image of 25% yellow, 25% magenta, 25% cyan, and 25% black was formed on the printing paper.

  After drawing by inkjet, drying was performed with a drying drum, and heat fixing was performed with a fixing drum to obtain a printed matter.

  In addition, as a comparative example, the conditions not applied to the back surface and the conditions in which an image is formed using suction belt conveyance and roller conveyance as the conveyance method were also examined. Adsorption belt conveyance was performed according to the method described in JP-A-2007-106511, and roller conveyance according to the method described in JP-A-2005-178252. The results are shown in FIG.

(Test Example 2)
The experiment was conducted by changing the basis weight of the recording medium and the applied amount of the aqueous solution under the conditions of the present invention of Test Example 1. The results are shown in FIG.

(Test Example 3)
In Test Example 1, printing was performed under the same conditions as in Test Example 1 except that printing on the recording medium 22 was changed from one side to both sides. In double-sided printing, after printing one side of the recording medium, the recording medium is reversed, and an aqueous solution is applied to the back surface (the surface on which an image has already been formed) in the same manner as in Example 1. An image was formed and double-sided printing was performed. The results are shown in FIG.

(Test Example 4)
In Test Example 2, double-sided printing was performed in the same manner as in Test Example 3 except that printing on the recording medium 22 was changed from one side to both sides. The results are shown in FIG.

(Test Example 5)
Single-sided printing was performed under the same conditions as in the present invention of Test Example 1 with the basis weight of the recording medium and the amount of aqueous solution applied being changed. The results are shown in FIG.

[Evaluation methods]
(Evaluation method for curling and trailing edge bounce)
The floating of the recording medium from the conveyance surface was measured. Curl measured the floating height of the four vertices of the paper and evaluated it by the arithmetic average height of four points. Further, the trailing edge jumping was evaluated by measuring the floating height of the highest part of the trailing edge with respect to the conveyance direction of the recording medium and calculating the arithmetic average height of two points.
◎ ・ ・ ・ less than 0.3mm ○ ・ ・ ・ 0.3mm or more and less than 0.5mm Δ ・ ・ ・ 0.5mm or more and less than 0.8mm × ・ ・ ・ 0.8mm or more (wrinkle evaluation method)
Wrinkles of the printed material were observed visually.
○ ... Wrinkles are not recognized.
Δ: Slight wrinkles are observed.
X ... Wrinkles are clearly recognized.

[result]
From Test Example 1 and Test Example 3, Experiment No. in which the aqueous solution was not applied to the back surface. In No. 1, curl was observed because of the difference in moisture content between the front and back surfaces of the recording medium. In addition, the experiment No. 1 used for conveying the suction belt. In the case of No. 2, the back surface of the recording medium was not dried, so that the amount of moisture contained in the recording medium was different between the front surface and the back surface of the recording medium, and curling was observed. Test No. in which the conveyance method is roller conveyance. As for No. 3, since the paper was locally extended because of roller conveyance, wrinkles were observed on the recording medium. Test No. 1 in which an aqueous solution was applied to the back surface of the recording medium and the conveyance method was drum conveyance. In No. 4, good printing with little occurrence of curling and wrinkling could be performed.

  In Test Examples 2 and 4 in which the image was formed by changing the thickness (basis weight) of the paper and the application amount of the aqueous solution, when the thickness of the paper was increased and the application amount of the aqueous solution was decreased, the occurrence of curling was observed. In addition, since a sufficient amount of moisture was not given to the recording medium, the adhesion between the drum and the recording medium was deteriorated during conveyance, and the trailing edge of the recording medium jumped up. In addition, Test No. As shown in 15, 16, 31, and 32, when the application amount of the aqueous solution increases, the moisture cannot be completely dried, so that there is a tendency for curling to occur.

  Moreover, the relationship between the basic weight of the printing paper (recording medium) in Example 5, and the application amount of aqueous solution is shown in FIG. Test Example 5 was comprehensively evaluated by curling and trailing edge jumping. As shown in FIG. 13, it can be confirmed that it is necessary to apply an aqueous solution suitable for the thickness (basis weight) of the recording medium in order to prevent the occurrence of curling and the trailing edge jump of the recording medium.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Paper feed part, 11 ... Aqueous solution supply part, 12 ... Treatment liquid provision part, 14 ... Drawing part, 16 ... Drying part, 18 ... Fixing part, 20 ... Discharge part, 22 ... Recording medium, 24: 1st intermediate conveyance part, 26 ... 2nd intermediate conveyance part, 28 ... 3rd intermediate conveyance part, 30 ... Intermediate conveyance body, 51 ... Aqueous solution application apparatus, 53 ... Aqueous solution roller, 55 ... Aqueous solution container, 57 Inkjet nozzle for aqueous solution, 59 ... coating outlet, 61 ... common flow path, 63 ... aqueous solution, 70 ... drawing drum, 72M, 72C, 72Y, 72K ... inkjet head, 76 ... drying drum, 84 ... fixing drum, 86 ... first 1 fixing roller, 88... Second fixing roller

Claims (14)

An aqueous solution application step of applying an aqueous solution containing water or a water-soluble organic solvent to the back surface of the recording medium;
An ink discharge step of holding the recording medium to which the water or the aqueous solution is applied with a drawing drum-shaped member, depositing ink on the surface of the recording medium, and forming an image;
A transport step of transporting by an intermediate transport body in a state where the back surface of the recording medium is opened;
Holding the recording medium with a drum-like member for drying, and drying the ink,
An ink jet recording method comprising adjusting an application amount of the water or the aqueous solution in accordance with a basis weight of the recording medium.   The application amount of the water or the aqueous solution is increased when the basis weight of the recording medium is large, and the application amount of the water or the aqueous solution is decreased when the basis weight of the recording medium is small. 2. The ink jet recording method according to 1. The inkjet recording method according to claim 1, wherein an application amount of the water or the aqueous solution is 0.1 g / m ² or more. The amount of water or the aqueous solution applied is
When the basis weight of the recording medium is 200 g / m ² or less, the basis weight is 10 g / m ² to 0.1 g / m ² or more and 0.25 g / m ² or less.
Claims basis weight of the recording medium when exceeding 200 g / ^{m 2,} characterized in that the basis weight of 10 g / ^{m 2} per recording medium is 0.24 g / ^{m 2} or more 5.0 g / ^{m 2} or less The inkjet recording method according to any one of 1 to 3.   The inkjet recording method according to claim 1, wherein the water or the aqueous solution is applied to an end portion of the recording medium. The drum-shaped member and the intermediate transport body include holding means,
The front end is held by the holding unit with respect to the conveyance direction of the recording medium, and more water or the aqueous solution is applied to the rear end portion than the front end portion for conveyance. The inkjet recording method according to item.   The inkjet recording method according to claim 1, wherein the water or the aqueous solution is applied by roller coating.   The inkjet recording method according to claim 1, wherein the water or the aqueous solution is applied by spraying.   The ink-jet recording method according to any one of claims 1 to 8, wherein the water-soluble organic solvent has an SP value of 30 or less. An aqueous solution applying means for applying an aqueous solution containing water or a water-soluble organic solvent to the back surface of the recording medium;
Ink ejection means for ejecting ink onto the surface of the recording medium to form an image; and
A drum-like member for drawing which is arranged opposite to the ink discharge means and holds and conveys the recording medium;
Drying means for drying the ink applied on the recording medium;
A drum member for drying that holds and conveys the recording medium disposed facing the drying means;
An intermediate transport body for transporting the recording medium from the drawing drum member to the drying drum member in a state where the back surface is opened;
A basis weight obtaining means for obtaining a basis weight of the recording medium;
An ink jet recording apparatus comprising: a control unit that adjusts an application amount of the water or the aqueous solution according to the basis weight acquired by the basis weight acquisition unit.   The control means increases the applied amount of the water or the aqueous solution when the basis weight of the recording medium is large, and decreases the applied amount of the water or the aqueous solution when the basis weight of the recording medium is small. The inkjet recording apparatus according to claim 10, wherein the inkjet recording apparatus is controlled. The drum-shaped member and the intermediate conveyance body include a holding unit that holds the leading end of the recording medium in the conveyance direction;
12. The ink jet recording apparatus according to claim 10, wherein the aqueous solution supply unit applies more water or the aqueous solution to the rear end portion of the recording medium than the front end portion.   The ink jet recording apparatus according to claim 10, wherein the aqueous solution applying unit is a applying unit using a roller.   The inkjet recording apparatus according to any one of claims 10 to 12, wherein the aqueous solution applying means is an applying means by spraying.

Images