JP5072108B2 - Image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming method and an image forming apparatus, and in particular, a processing liquid that reacts with a colorant component in ink is applied to a recording medium, and an ink is ejected onto the recording medium to which the processing liquid is applied. The present invention relates to an image forming method and an image forming apparatus.

  2. Description of the Related Art An ink jet recording apparatus that records an image on a recording medium by ejecting ink droplets from nozzles of a recording head (ink jet head) is widely used. This ink jet recording apparatus has low noise, low running cost, and can perform high-quality image recording on various recording media.

  By the way, when recording on a coated paper (slowly penetrating medium) having a low penetration by an ink jet recording method, ink droplets (ink dots) ejected by the recording head are blotted on the recording medium. There is a problem that the image quality of the recorded image is deteriorated due to the influence.

Therefore, as a technique for solving the above problem, a technique is known in which a treatment liquid that reacts with a color material component in ink is applied to the recording medium before ink is ejected onto the recording medium (for example, Patent Documents). 1 and 2).
JP-A-8-52867 JP 2008-6734 A

  However, when ink dots are ejected after the treatment liquid is applied to the recording medium, the ink dots can be prevented from spreading, but the ink dots become too small and cannot be controlled to an appropriate dot diameter.

  Patent Document 1 describes that the dot diameter is controlled by controlling whether or not the treatment liquid is applied. However, when the treatment liquid is not applied (particularly, a coated paper for printing is used as a recording medium). In this case, the dot shape is greatly disturbed, and bleeding of different colors occurs to cause image deterioration. Furthermore, there is also a problem that the offset to the hot-pressing roller during fixing is greatly deteriorated.

  Also, when ink dots are ejected after the treatment liquid is applied to the recording medium, the ink dots do not come into contact with the recording medium, and the ink dots float on the treatment liquid film, and the dot formation position is greatly disturbed. There's a problem.

  Further, in Patent Document 2, in order to obtain an ideal dot shape, processing is performed in the recording medium by changing the distance from the processing liquid applicator to the recording head (printing head) according to the conveyance speed of the recording medium. Ink droplets are ejected after the liquid has penetrated, but with this method, if printing is attempted at a high speed on coated paper that is slow to penetrate, the distance between the treatment liquid applicator and the recording head becomes longer. It will be too much, leading to an increase in the size of the device.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image forming method and an image forming apparatus capable of controlling the ink dot diameter while preventing the color material from floating.

In order to achieve the above object, an image forming method according to the present invention (the invention according to claim 1) includes a recording mode determining step for determining an arbitrary recording mode from a plurality of recording modes, and a recording medium. A treatment liquid application step for applying a treatment liquid containing a component that reacts with ink, and a treatment liquid drying condition is selected from a plurality of treatment liquid drying conditions according to the recording mode determined in the recording mode determination step. A treatment liquid drying process for drying a treatment liquid applied on the recording medium according to a treatment liquid drying condition selection process, a treatment liquid drying condition selected in the treatment liquid drying condition selection process, and the treatment liquid drying process. after being made, based on the recording mode determined by the input image data the recording mode determining step, see it contains a ink droplet deposition step of droplet of ink droplets to the recording medium, the droplet ejection density Is different Of the plurality of recording modes, the droplet ejection density in the first recording mode is larger than the droplet ejection density in the second recording mode, and is selected according to the first recording mode in the treatment liquid drying condition selection step. The first treatment liquid drying condition is characterized in that the drying amount of the treatment liquid is larger than the second treatment liquid drying condition selected in accordance with the second recording mode .

According to the present invention, after the treatment liquid is applied onto the recording medium, the drying process of the treatment liquid is performed before the ink droplets are ejected. By controlling the drying of the treatment liquid according to the treatment liquid drying conditions selected according to the recording mode, the ink dot diameter can be controlled with high accuracy. As a result, it is possible to improve the image quality.
In particular, in the present invention, in the first recording mode (high resolution mode), the processing liquid drying condition (drying) is performed so that the amount of processing liquid to be dried is larger than that in the second recording mode (low resolution mode). Strength) is set. Thereby, the ink dot diameter in the first recording mode is smaller than the ink dot diameter in the second recording mode, and a preferable image can be obtained according to the image recording mode.

  According to a second aspect of the present invention, in the image forming method according to the first aspect, the plurality of recording modes have different droplet ejection densities, and droplets are ejected when ink droplets are ejected according to the respective recording modes. The quantities are substantially the same.

  According to the second aspect of the present invention, recording is performed even when the droplet amount (droplet ejection amount) of ink droplets ejected corresponding to a plurality of recording modes having different droplet ejection densities is substantially the same. By controlling the drying of the treatment liquid in accordance with the treatment liquid drying conditions selected according to the mode, the ink dot diameter can be controlled with high accuracy.

  The “substantially the same” means that the variation of the appropriate amount of liquid is about ± 0.1 pl.

According to a third aspect of the present invention, in the image forming method according to the first or second aspect , the image forming method further includes an image fixing step of fixing the image formed on the recording medium while pressing the image with a heating member. .

According to the third aspect of the present invention, the ink coloring material adheres to the heating member even at the time of image fixing by performing the ink droplet ejection after drying the treatment liquid applied on the recording medium. And a good fixed image can be obtained without image deterioration.

According to a fourth aspect of the present invention, the image forming method according to any one of the first to third aspects further includes a medium temperature detecting step of detecting a temperature of the recording medium, and the processing liquid drying condition selecting step. Is characterized in that a treatment liquid drying condition is selected according to the temperature of the recording medium detected in the medium temperature detecting step.

According to the fourth aspect of the present invention, the ink dot diameter can be controlled with high accuracy without being influenced by the temperature of the recording medium.

According to a fifth aspect of the present invention, in the image forming method according to any one of the first to fourth aspects, the method further includes a medium type detecting step of detecting the type of the recording medium, and the process liquid drying condition selecting step. Is characterized in that the treatment liquid drying conditions are determined according to the type of the recording medium detected in the medium type detecting step.

According to the fifth aspect of the present invention, it is possible to control the ink dot diameter with high accuracy without depending on the type of the recording medium.

In order to achieve the above object, an image forming apparatus according to the present invention (the invention according to claim 6 ) includes a recording mode determining means for determining an arbitrary recording mode from a plurality of recording modes, and a recording medium. In contrast, a treatment liquid application unit that applies a treatment liquid containing a component that reacts with ink, and a treatment liquid drying condition according to the recording mode determined by the recording mode determination unit from among a plurality of treatment liquid drying conditions. A processing liquid drying condition selection means to select; a processing liquid drying means for drying the processing liquid applied on the recording medium in accordance with the processing liquid drying conditions selected by the processing liquid drying condition selection means; Ink droplet ejecting means for ejecting ink droplets to the recording medium based on the input image data and the recording mode determined by the recording mode determining means after the treatment liquid applied to the recording medium is dried The provided among the droplet deposition density different recording modes, droplet deposition density of the first recording mode is greater than the droplet ejection density of the second recording mode, the first in the processing liquid drying condition selection means The first treatment liquid drying condition selected in accordance with the recording mode is larger in the drying amount of the treatment liquid than the second treatment liquid drying condition selected in accordance with the second recording mode. And

According to the present invention, after the treatment liquid is applied onto the recording medium, the drying process of the treatment liquid is performed before the ink droplets are ejected. By controlling the drying of the treatment liquid according to the treatment liquid drying conditions selected according to the recording mode (that is, the image resolution), the ink dot diameter can be controlled with high accuracy. As a result, it is possible to improve the image quality.
In particular, in the present invention, in the first recording mode (high resolution mode), the processing liquid drying condition (drying) is performed so that the amount of processing liquid to be dried is larger than that in the second recording mode (low resolution mode). Strength) is set. Thereby, the ink dot diameter in the first recording mode is smaller than the ink dot diameter in the second recording mode, and a preferable image can be obtained according to the image recording mode.

According to the present invention, after the treatment liquid is applied onto the recording medium, the drying process of the treatment liquid is performed before the ink droplets are ejected. By controlling the drying of the treatment liquid according to the treatment liquid drying conditions selected according to the recording mode (that is, the image resolution), the ink dot diameter can be controlled with high accuracy. As a result, it is possible to improve the image quality.
In particular, in the present invention, in the first recording mode (high resolution mode), the processing liquid drying condition (drying) is performed so that the amount of processing liquid to be dried is larger than that in the second recording mode (low resolution mode). Strength) is set. Thereby, the ink dot diameter in the first recording mode is smaller than the ink dot diameter in the second recording mode, and a preferable image can be obtained according to the image recording mode.

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

[Overall configuration of inkjet recording apparatus]
First, an ink jet recording apparatus will be described as an embodiment of an image forming apparatus according to the present invention.

  FIG. 1 is a schematic configuration diagram illustrating a configuration example of an ink jet recording apparatus according to the present embodiment. An inkjet 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, a treatment liquid application unit 12, a drawing unit 14, a drying unit 16, a fixing unit 18, and the like. The discharge unit 20 is configured. A recording medium 22 (sheets) is stacked on the paper supply unit 10, and the recording medium 22 is sent from the paper supply unit 10 to the treatment liquid application unit 12, and the treatment liquid application unit 12 processes the treatment liquid on the recording surface. 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.

  Hereinafter, each unit of the inkjet recording apparatus 1 (the paper feeding unit 10, the processing liquid applying unit 12, the drawing unit 14, the drying unit 16, the fixing unit 18, the discharging unit 20, the first to third intermediate conveying 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.

(Processing liquid application part)
The processing liquid application unit 12 is a mechanism that applies the processing liquid to the recording surface of the recording medium 22.

  The treatment liquid is a liquid containing a component that aggregates or thickens the color material (pigment or dye) in the 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 processing liquid will be described in detail later.

  Means for causing the reaction between the ink and the treatment liquid include a method of reacting an anionic coloring material in the ink and a cationic compound in the treatment liquid, and mixing the ink and the treatment liquid having different pHs to each other to adjust the pH of the ink. There is a method of causing dispersion and destruction of the pigment in the ink by changing the color and aggregating the pigment, and a method of causing dispersion and destruction of the pigment in the ink by reaction with the polyvalent metal salt in the treatment liquid and aggregating the pigment.

  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 processing liquid drum 54 is provided with a claw-shaped holding means on its outer peripheral surface, and the leading 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.

  The processing liquid drying control, which is a characteristic part of the present invention, will be described in detail later.

(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. Further, the drawing drum 70 is provided with a claw-shaped holding means (not shown) on its outer peripheral surface, and the leading end of the recording medium 22 can be held by this holding means. 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. Each color ink contains at least pigment particles, a dispersant polymer for coating the pigment, and self-dispersing polymer fine particles.

  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.

  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. Further, the fluctuation of the speed due to the fluctuation of the drawing drum 70 or the like is learned in advance, and the droplet ejection timing obtained by the encoder 91 is corrected to obtain the fluctuation 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. However, it is necessary to arrange the recording medium 22 from the upstream side in the traveling direction in the order of the ink having the smallest surface tension. A more detailed description of the ink jet heads 72M, 72C, 72Y, and 72K and a detailed description of ink will be described later.

(Drying part)
The drying unit 16 is a step of drying the solvent (water) separated by the color material aggregation action. The drying unit 16 and a first IR heater 78 disposed at a position facing the outer peripheral surface of the drying drum 76. , A hot air jet nozzle 80 and a second IR heater 82. 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 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 amount of residual water in the ink after the drying treatment is preferably 1 g / m ² or more and 4 g / m ² or less. If the remaining water amount exceeds 4 g / m ² , ink adhesion (offset) to the roller during fixing deteriorates. Further, when the amount of residual water is less than 1 g / m ² , the deformation (curl) of the paper is deteriorated.

  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)
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 is provided with a claw-shaped holding means on its outer peripheral surface, and the leading end of the recording medium 22 can be held by this holding means. 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, each of the first fixing roller 86 and the second fixing roller 88 is disposed so as to come into pressure contact with the fixing drum 84 at a predetermined pressure (for example, 0.3 MPa). A nip roller is configured between the two. 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 at a predetermined nip pressure (for example, 1 MPa). The nipping is performed 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.). 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.

(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).

  Claw-shaped holding means are provided at 90 ° intervals on the outer peripheral surface of the intermediate conveyance body 30. 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.

  In the inkjet recording apparatus 1 of the present embodiment, it is preferable that a medium type detecting unit that detects the type of the recording medium 22 and a medium temperature detecting unit that detects the temperature of the recording medium 22 are provided. In particular, the medium temperature detecting means is preferably arranged adjacent to the processing liquid drying means (the hot air blowing nozzle 58 and the IR heater 60). As will be described later, by controlling the processing liquid drying means according to the processing liquid drying conditions selected according to the type and temperature of the recording medium 22, the ink is not affected by the type and temperature of the recording medium 22. The dot diameter can be controlled with higher accuracy.

(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.

  FIG. 2A is a plan perspective view showing an example of the structure of the inkjet head 100, and FIG. 2B 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. 2A and 2B, the ink jet 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, etc.). 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. 2) substantially orthogonal to the conveying direction of the recording medium 22 (arrow S in FIG. 2). The form is not limited to the illustrated example. For example, instead of the configuration of FIG. 2 (a), as shown in FIG. 3, a long head module 100 ′ in which a plurality of nozzles 102 are two-dimensionally arranged is arranged in a staggered manner and joined together 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. 2A and 2B), 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. 4 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. 2A). FIG.

  As shown in FIG. 4, 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. 4). 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. 5, the ink chamber unit 108 having the structure described above 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 driving a nozzle with 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 the nozzles 102 arranged in a matrix as shown in FIG. 5 are driven, main scanning as described in (3) above 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 by sequentially driving 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 this embodiment, a method of ejecting ink droplets by deformation of an actuator 116 typified by a piezo element (piezoelectric element) is adopted. However, in the practice of the present invention, a method of ejecting ink is not particularly limited. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

(Description of control system)
FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 1. The ink jet recording apparatus 1 includes a communication interface 120, a system controller 122, a print controller 124, a treatment liquid application controller 126, a first intermediate transport controller 128, a head driver 130, a second intermediate transport controller 132, and a drying controller 134. A third intermediate transport 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.

  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 controller 126, the first intermediate transport controller 128, the head driver 130, the second intermediate transport controller 132, the drying controller 134, and the third intermediate transport controller 136. , Fixing control unit 138, memory 144, motor driver 142, heater driver 146, suction control unit 149, and the like to control communication with host computer 150, read / write control of memory 144, etc. A control signal for controlling the motor 152 and the heater 154 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. 6, a motor 152 disposed in each part in the apparatus is represented by reference numeral 152. For example, the motor 152 shown in FIG. 6 includes a motor for driving 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. 6, 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. 6 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. 6, the image buffer memory 148 is shown in a mode associated with the print control unit 124, but it 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.

  Further, the system controller 122 includes a processing liquid application control unit 126, a first intermediate conveyance control unit 128, a second intermediate conveyance control unit 132, a drying control unit 134, a third intermediate conveyance control unit 136, a fixing control unit 138, and suction control. The unit 149 is controlled.

  The processing liquid application control unit 126 controls the operation of the processing liquid application device 56 of the processing 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 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.

[Processing liquid drying control]
Next, processing liquid drying control will be described.

  As will be apparent from an evaluation experiment to be described later, after the treatment liquid is applied onto the recording medium 22 and before the ink droplets are ejected, it is constituted by the hot air blowing nozzle 58 and the IR heater 60 of the treatment liquid application unit 12. When the treatment liquid is dried by the treatment liquid drying means, the ink dot diameter can be controlled by changing the drying condition (dry strength) of the treatment liquid.

  Therefore, in the inkjet recording apparatus 1 of the present embodiment, the processing liquid drying means (the hot air blowing nozzle 58 and the IR heater) of the processing liquid application unit 12 is selected according to the recording mode designated by the user from among a plurality of different recording modes. The drying condition of the processing liquid according to 60) is set, and the ink dot diameter is controlled by drying the processing liquid according to the condition. Hereinafter, this control will be described in detail.

  FIG. 7 is a flowchart showing processing liquid drying control. Each process shown in this flowchart is mainly executed by the system controller 122 shown in FIG.

  First, when the inkjet recording apparatus 1 is instructed to start printing, information on the ink dot diameter with respect to a plurality of treatment liquid drying conditions (dry strength) that can be controlled by the treatment liquid drying means (hereinafter referred to as “dot diameter information”). Is acquired (step S10).

  This dot diameter information may be stored in advance in the apparatus by storing it in a memory or the like. However, as can be seen from an evaluation experiment described later, the degree of penetration of the treatment liquid varies depending on the type and temperature of the recording medium 22. As a result, the ink dot diameter may be different even under the same treatment liquid drying conditions. Therefore, it is preferable that the dot diameter information is created by measuring the ink dot diameter when the drying condition (drying strength) of the treatment liquid by the treatment liquid drying means is changed as a test chart at the start of printing. The ink dot diameter can be controlled with high accuracy without being affected by the type and temperature of the recording medium 22.

  Of course, the dot diameter information is obtained in advance by experiments and the like, and the dot diameter information is stored in a predetermined memory (for example, the memory 144) in a data table, and when the start of printing is instructed, the memory automatically You may make it read automatically.

  FIG. 8 is a diagram showing an example of the dot diameter information table. In the example shown in the figure, the treatment liquid drying condition (dry strength) is Lv. 1-Lv. 3 of three levels, Lv. 1, Lv. 2, Lv. The dry strength increases in the order of 3. This means that the higher the drying strength, the smaller the remaining amount of the processing liquid applied on the recording medium 22, and the smaller the ink dot diameter.

  Further, as described above, the degree of penetration of the treatment liquid into the recording medium 22 varies depending on the type and temperature of the recording medium 22, and the ink dot diameter may vary even under the same drying conditions. In step S10, it is preferable that a plurality of dot diameter information (dot diameter information table) is created for each type and temperature of the recording medium 22 and the dot diameter information is acquired according to the type and temperature of the recording medium 22.

  Next, a recording mode designated by the user is acquired from a plurality of recording modes (step S12), and a necessary dot diameter is determined from the recording mode designated by the user (step S14).

  The relationship between a plurality of recording modes and the corresponding ink dot diameters (necessary dot diameters) is stored in a data table and stored in a predetermined memory (for example, the memory 144). When a user-specified recording mode is acquired, The required dot diameter is determined with reference to the memory.

  FIG. 9 is a diagram showing an example of a recording mode table showing the correspondence between the recording mode and the dot diameter. In the example shown in the figure, there are three image recording modes, and there are a high-quality mode, a standard mode, and a high-speed mode in descending order of resolution. The required dot diameter (ink dot diameter) derived from the resolution of each recording mode is the smallest in the high quality mode and the largest in the high speed mode.

  Next, the treatment liquid drying conditions are determined from the necessary dot diameter (step S16). For example, when the user designates the high image quality mode, the necessary dot diameter 20 [μm] is determined from the recording mode table shown in FIG. Then, from the dot diameter information table shown in FIG. 8, the treatment liquid drying conditions Lv. 1 is determined.

  Then, the processing liquid drying means is controlled in accordance with the processing liquid drying conditions determined in step S16, and the solvent component of the processing liquid applied on the recording medium 22 is dried. Ink droplets are ejected by the heads 72M, 72C, 72Y, and 72K, and a desired ink dot diameter is realized on the recording medium 22.

〔recoding media〕
The recording medium used in the present invention is not particularly limited, but a particularly preferable result can be obtained with respect to the coated paper for printing in which the penetration of the ink solvent is slow.

  Examples of the support that can be suitably used for coated paper include chemical pulps such as LBKP and NBKP; mechanical pulps such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP; wood pulps such as waste paper pulp such as DIP And a pigment as a main component, and at least one binder such as a sizing agent, a fixing agent, a yield improver, a cationizing agent, and a paper strength enhancer are mixed together to produce a long net paper machine and circular net paper machine. Base paper manufactured using various machines such as a machine, twin-wire paper machine, base paper provided with size press or anchor coat layer using starch, polyvinyl alcohol, etc., or of these size press or anchor coat layer Examples thereof include coated paper such as art paper, coated paper, cast coated paper and the like, on which a coating layer is provided.

  In the method of the present invention, these base papers or coated papers may be used as they are, or for example, a calendar process is performed using a machine calendar, a TG calendar, a soft calendar, or the like, and the flattening is controlled. May be used.

The basis weight of the support is usually about 40 to 300 g / m ² , but is not particularly limited. The coated paper used in the present invention is coated with a coating layer on the support as described above. The coating layer is composed of a coating composition mainly composed of a pigment and a binder, and is coated on at least one layer on the support.

  As the pigment, a white pigment can be preferably used. Examples of such white pigments include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, Inorganic pigments such as diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, hydrous halloysite, magnesium hydroxide; styrene plastic pigments, Examples thereof include organic pigments such as acrylic plastic pigment, polyethylene, microcapsule, urea resin, melamine resin.

Examples of the binder include starch derivatives such as oxidized starch, etherified starch, and phosphate esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, polyvinyl alcohol or derivatives thereof; various saponification degrees Polyvinyl alcohol or various derivatives thereof such as silanol-modified products, carboxylated products, and cationized products thereof; conjugated diene copolymer latexes such as polyvinylpyrrolidone, maleic anhydride resin, styrene-butadiene copolymer, and methyl methacrylate-butadiene copolymer Acrylic polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester; vinyl polymer latex such as ethylene vinyl acetate copolymer; Functional group-modified polymer latex with functional group-containing monomers such as xy groups; water-based adhesives such as thermosetting synthetic resins such as melamine resins and urea resins; acrylics such as polymethyl methacrylate; acid esters; Polymer or copolymer resin; Synthetic resin adhesives such as polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin, and the like.
The blending ratio of the pigment and binder in the coating layer is 3 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the pigment. When the blending ratio of the binder with respect to 100 parts by weight of the pigment is less than 3 parts by weight, the coating strength of the ink receiving layer made of such a coating composition may be insufficient. On the other hand, when the blending ratio exceeds 70 parts by weight, the absorption of the high boiling point solvent becomes extremely slow.

  Further, the coating layer includes, for example, a dye fixing agent, a pigment dispersant, a thickener, a fluidity improver, an antifoaming agent, a foam suppressor, a release agent, a foaming agent, a penetrating agent, a coloring dye, a coloring pigment, Various additives such as a fluorescent whitening agent, an ultraviolet absorber, an antioxidant, an antiseptic, an antibacterial agent, a water resistant agent, a wet paper strength enhancer, and a dry paper strength enhancer can be appropriately blended.

The coating amount of the ink receiving layer varies depending on the required gloss, ink absorbability, type of support, etc., and cannot be generally stated, but is usually 1 g / m ² or more. Further, the ink receiving layer may be applied by dividing a certain coating amount into two portions. When coating is performed in two steps in this way, the gloss is improved as compared with the case where the same coating amount is applied once.

  Coating of the coating layer is performed by using various devices such as various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain coaters, short dwell coaters, and size presses on-machine or off-machine. be able to. Further, after coating the coating layer, the ink receiving layer may be flattened using a calendar device such as a machine calendar, a TG calendar, or a soft calendar.

In addition, the number of coat layers can be appropriately determined as necessary.
Coated paper includes art paper, high-quality coated paper, medium-quality coated paper, high-quality lightweight coated paper, medium-sized lightweight coated paper, and fine-coated printing paper. The coating amount of the coating layer is about 40 g / m2 on both sides of art paper. High-quality coated paper and medium-sized coated paper have a double-sided surface of about 20 g / m2, and high-quality lightweight coated paper and medium-sized and lightweight coated paper have a double-sided surface of about 15 g / m2. Examples of art paper include Tokuhishi Art, Ulite as high-quality coated paper, Tohoku Art (made by Mitsubishi Paper Industries), satin Kinto (made by Oji Paper Co., Ltd.), etc. as art paper, Examples of coated paper include OK Top Coat (Oji Paper Co., Ltd.), Aurora Coat (Nippon Paper Co., Ltd.), and Recycle Coat T-6 (Nippon Paper Co., Ltd.). , New V mat (Mitsubishi Paper Co., Ltd.), New Age (Oji Paper Co., Ltd.), Recycle Mat T-6 (Nihon Paper Co., Ltd.), Pisum (Nihon Paper Co., Ltd.). Examples of the fine coated printing paper include Aurora L (manufactured by Nippon Paper Industries Co., Ltd.), Kinmari Hi-L (manufactured by Hokuetsu Paper Industries Co., Ltd.) and the like. Further, examples of the cast coated paper include SA Kanto Plus (manufactured by Oji Paper Co., Ltd.), Hi McKinley Art (manufactured by Gojo Paper Co., Ltd.), and the like.

[Water-based ink]
Next, the water-based ink used in the present invention will be described in detail. The aqueous ink includes at least a resin dispersant (A), a pigment (B) dispersed by the resin dispersant (A), self-dispersing polymer fine particles (C), and an aqueous liquid medium (D). Yes.

<Resin dispersant (A)>
The resin dispersant (A) is used as a dispersant for the pigment (B) in the aqueous liquid medium (D), and any resin that can disperse the pigment B may be used. The structure of the agent (A) preferably has a hydrophobic structural unit (a) and a hydrophilic structural unit (b). If necessary, the resin dispersant (A) can include a structural unit (c) different from the hydrophobic structural unit (a) and the hydrophilic structural unit (b).

  The composition of the hydrophilic structural unit (b) and the hydrophobic structural unit (a) depends on the degree of hydrophilicity and hydrophobicity of each, but the hydrophobic structural unit (a) is the entire resin dispersant (A). It is preferable to contain more than 80 mass% with respect to the mass of, and 85 mass% or more is more preferable. That is, the hydrophilic structural unit (b) needs to be 15% by mass or less, and when the hydrophilic structural unit (b) is more than 15% by mass, the aqueous liquid medium alone does not contribute to the dispersion of the pigment. The component dissolved in (D) increases, which deteriorates various properties such as the dispersibility of the pigment (B), and causes the discharge properties of the inkjet recording ink to deteriorate.

  Specific preferred examples of the resin dispersant (A) in the present invention are shown below, but the present invention is not limited to the following.

<Ratio of pigment (B) to resin dispersant (A)>
The weight ratio of the pigment (B) and the resin dispersant (A) is preferably 100: 25 to 100: 140, and more preferably 100: 25 to 100: 50. When the resin dispersant is 100: 25 or more, the dispersion stability and the abrasion resistance tend to be improved. When the resin dispersant is 100: 140 or less, the dispersion stability tends to be improved.

<Pigment (B)>
In the present invention, the pigment (B) is a colored substance (inorganic) which is almost insoluble in water and organic solvents, as described on page 518 of the Chemical Dictionary 3rd edition published on April 1, 1994 (edited by Michinori Oki et al.). In the present invention, organic pigments and inorganic pigments can be used.

  In the present invention, the “pigment (B) dispersed by the resin dispersant (A)” means a pigment dispersed and held by the resin dispersant (A), and the resin dispersed in the aqueous liquid medium (D). The pigment is preferably used as a pigment dispersed and held using the agent (A). The aqueous liquid medium (D) may or may not contain a dispersant.

  In the present invention, the pigment (B) dispersed by the resin dispersant (A) is not particularly limited as long as it is a pigment dispersed and held by the resin dispersant (A). From the viewpoint of ejection stability, a microencapsulated pigment produced by a phase inversion method is more preferable.

  A preferred example of the pigment (B) contained in the present invention is a microencapsulated pigment. The microencapsulated pigment is a pigment in which the pigment is coated with the resin dispersant (A).

  The resin of the microencapsulated pigment needs to use the resin dispersant (A), and is a polymer having self-dispersibility or solubility in water and an anionic group (acidic). It is preferable to use the compound for a resin other than the resin dispersant (A).

  Examples of pigments that can be used in the present invention include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 14C, 16, 17, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74, 75, 81, 83, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 114, 117, 120, 128, 129, 138, 150, 151, 153, 154, 155, 180 etc. are mentioned.

  Examples of magenta ink pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 48 (Ca), 48 (Mn), 48: 2, 48: 3, 48: 4, 49, 49: 1, 50, 51, 52, 52: 2, 53: 1, 53, 55, 57 (Ca), 57: 1, 60, 60: 1, 63: 1, 63: 2, 64, 64: 1, 81, 83, 87, 88, 89, 90, 101 (Bengara) ), 104, 105, 106, 108 (cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 163, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 209, 2 9 and the like, in particular, C. I. Pigment Red 122 is preferable.

  Further, as pigments for cyan ink, C.I. I. Pigment blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17: 1, 22, 25, 56, 60, C.I. I. Bat blue 4, 60, 63 and the like. I. Pigment Blue 15: 3 is preferable.

  Examples of other color ink pigments include C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19 (quinacridone red), 23, 38, and the like. In addition, processed pigments such as graft carbon whose surface is treated with a resin or the like can also be used.

An example of the black type is carbon black. Specific examples of such carbon black include No. 1 manufactured by Mitsubishi Chemical. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, No2200B, etc. are Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc., manufactured by Columbia, Regal 400R, Regal 330R, Regal 800R, Mal 80 , Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. are Color Black made by Degussa.
FW1, ColorBlack FW2, Color Black FW2V, Color Black FW18, Color Black FW200, ColorBlack S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black4A , Special Black 4 and the like.

  The above pigments may be used alone or in combination of a plurality selected from the above-mentioned groups or between the groups.

  The content of the pigment (B) in the aqueous ink in the present invention is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, and 2 to 6% by mass from the viewpoint of dispersion stability and concentration of the aqueous ink. % Is particularly preferred.

<Self-dispersing polymer fine particles (C)>
The water-based ink used in the present invention contains at least one kind of self-dispersing polymer fine particles. The self-dispersing polymer fine particles in the present invention are water-insoluble which can be dispersed in an aqueous medium by a functional group (particularly an acidic group or a salt thereof) of the pr resin itself in the absence of other surfactant. It refers to fine particles of a water-insoluble polymer which is a polymer and does not contain a free emulsifier.

  Here, the dispersed state refers to both an emulsified state (emulsion) in which a water-insoluble polymer is dispersed in an aqueous medium and a dispersed state (suspension) in which a water-insoluble polymer is dispersed in an aqueous medium in a solid state. It includes the state of.

  The water-insoluble polymer in the present invention is a water-insoluble polymer that can be in a dispersed state in which the water-insoluble polymer is dispersed in a solid state from the viewpoint of ink aggregation rate and ink fixability when contained in a water-soluble ink. preferable.

  The self-dispersing polymer fine particles in the present invention include a structural unit derived from an aromatic group-containing (meth) acrylate monomer, and the content is preferably 10% by mass to 95% by mass. When the content of the aromatic group-containing (meth) acrylate monomer is 10% by mass to 95% by mass, the stability of the self-emulsification or dispersion state can be improved, and further the increase in ink viscosity can be suppressed.

  In the present invention, from the viewpoints of stability in a self-dispersing state, stabilization of particle shape in an aqueous medium due to hydrophobic interaction between aromatic rings, and reduction in the amount of water-soluble components due to appropriate hydrophobicization of particles. More preferably, the content is from mass% to 90 mass%, more preferably from 15 mass% to 80 mass%, and particularly preferably from 25 mass% to 70 mass%.

  The self-dispersing polymer fine particles in the present invention can be composed of, for example, a structural unit composed of an aromatic group-containing monomer and a structural unit composed of a dissociable group-containing monomer. Can further be included.

  The molecular weight range of the water-insoluble polymer constituting the self-dispersing polymer fine particles in the present invention is preferably 3000 to 200,000, more preferably 5000 to 150,000, and more preferably 10,000 to 100,000 in terms of weight average molecular weight. More preferably it is. By setting the weight average molecular weight to 3000 or more, the amount of water-soluble components can be effectively suppressed. Moreover, self-dispersion stability can be improved by making a weight average molecular weight into 200,000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC).

  From the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer, the water-insoluble polymer constituting the self-dispersing polymer fine particles in the present invention comprises an aromatic group-containing (meth) acrylate monomer as a copolymerization ratio of 15 to 90% by mass, a carboxyl group-containing monomer, And an alkyl group-containing monomer, preferably having an acid value of 25 to 100 and a weight average molecular weight of 3000 to 200,000, and an aromatic group-containing (meth) acrylate monomer as a copolymerization ratio of 15 to 80 mass. %, A carboxyl group-containing monomer, and an alkyl group-containing monomer, an acid value of 25 to 95, and a weight average molecular weight of 5000 to 150,000 are more preferable.

  The average particle size of the self-dispersing polymer fine particles in the present invention is preferably in the range of 10 to 400 nm, more preferably 10 to 200 nm, and further preferably 10 to 100 nm. Manufacturability is improved when the average particle diameter is 10 nm or more. Moreover, storage stability improves by setting it as an average particle diameter of 400 nm or less.

  Further, the particle size distribution of the self-dispersing polymer fine particles is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Further, two or more kinds of water-insoluble particles may be mixed and used.

  The average particle size and particle size distribution of the self-dispersing polymer fine particles can be measured using, for example, a light scattering method.

  The self-dispersing polymer fine particles of the present invention can be suitably contained in, for example, an aqueous ink composition, and can be used alone or in combination of two or more.

<Aqueous liquid medium (D)>
In the inkjet recording water-based ink, the aqueous liquid medium (D) represents a mixture of water and a water-soluble organic solvent. Water-soluble organic solvents (hereinafter also referred to as “water-soluble organic solvents”) are used for the purpose of drying inhibitors, wetting agents or penetration enhancers.

  The ink composition uses a water-soluble solvent for the purpose of an anti-drying agent, a wetting agent or a penetration accelerator. In particular, when used as an aqueous ink composition of an ink jet recording system, a water-soluble organic solvent is preferably used for the purpose of a drying inhibitor, a wetting agent or a penetration accelerator.

  Anti-drying agents and wetting agents are used for the purpose of preventing clogging due to drying of the ink-jet ink at the nozzles, and the anti-drying agents and wetting agents are water-soluble organic compounds having a vapor pressure lower than that of water. Solvents are preferred.

  In addition, a water-soluble organic solvent is preferably used as a penetration accelerator for the purpose of allowing the ink composition (particularly, the ink-jet ink composition) to penetrate into paper better.

  In the present invention, for the purpose of suppressing curling, (a) the water-soluble solvent contains 90% by mass or more of a water-soluble solvent having an SP value of 27.5 or less, and is represented by the following structural formula (1). Containing compounds. Here, the “water-soluble solvent having an SP value of 27.5 or less” and the “compound represented by the structural formula (1)” may be the same or different.

  The solubility parameter (SP value) of the water-soluble 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 (1967), and this numerical value is adopted in the present invention.

    In the structural formula (1), l, m, and n are each independently an integer of 1 or more and represent 1 + m + n = 3-15.

  When l + m + n is less than 3, the curl suppressing force is small, and when it exceeds 15, the discharge property is deteriorated.

  Among the above, l + m + n is preferably 3 to 12, and more preferably 3 to 10.

  In the structural formula (1), AO represents ethyleneoxy and / or propyleneoxy, and among them, a propyleneoxy group is preferable.

Each AO of (AO) ₁ , (AO) _m , and (AO) _n may be the same or different.

  Examples of the water-soluble solvent having an SP value of 27.5 or less and the compound represented by the structural formula (1) are shown below together with the SP value (in parentheses). However, the present invention is not limited to this.

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 ( in AO = EO or PO, the ratio of EO: PO = 1: 1)
(20.1)
_{· NC 4 H 9 O (AO} ) 10 -H ( in AO = EO or PO, the ratio of EO: PO = 1: 1) (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, the 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)
In the present invention, EO and PO represent an ethyleneoxy group and a propyleneoxy group.

  The proportion (content) of the compound of the structural formula (1) in the (a) water-soluble solvent is preferably 10% or more, more preferably 30% or more, and further preferably 50% or more. Even if the value is high, no problem arises.

  By setting it in the above range, curling can be suppressed without deteriorating the stability and dischargeability of the ink, which is preferable.

  The water-soluble solvent (a) used in the present invention may be used alone or in combination of two or more.

  (A) The content of the water-soluble solvent is preferably 1% by mass or more and 60% by mass or less, and more preferably 5% by mass or more and 40% by mass or less from the viewpoint of ensuring stability and ejection reliability in the entire ink composition. Preferably, 10 mass% or more and 30 mass% or less are used especially preferably.

  The amount of water (c) used in the present invention is not particularly limited, but is preferably 10% by mass or more and 99% by mass or less from the viewpoint of ensuring stability and ejection reliability in the entire ink composition. More preferably, they are 30 mass% or more and 80 mass% or less, More preferably, they are 50 mass% or more and 70 mass% or less.

<Surfactant>
It is preferable to add a surfactant (hereinafter also referred to as a surface tension adjusting agent) to the water-based ink in the invention. Examples of the surfactant include nonionic, cationic, anionic and betaine surfactants. The addition amount of the surface tension adjusting agent is preferably an amount for adjusting the surface tension of the water-based ink in the present invention to 20 to 60 mN / m, more preferably 20 to 45 mN / m, in order to eject ink droplets well by inkjet. More preferably, the amount can be adjusted to 25 to 40 mN / m.

  As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactant, cationic surfactant, amphoteric surfactant, nonionic surfactant Any of the surfactants can be used. Furthermore, the above-mentioned polymer substance (polymer dispersing agent) can also be used as a surfactant.

<Other ingredients>
The water-based ink used in the present invention may contain other additives. Other additives include, for example, ultraviolet absorbers, anti-fading agents, anti-mold agents, pH adjusters, rust inhibitors, antioxidants, emulsion stabilizers, preservatives, antifoaming agents, viscosity modifiers, and dispersion stabilizers. Known additives such as agents and chelating agents are included.

[Treatment solution]
The aqueous treatment liquid in the present invention contains at least one fixing agent for fixing components in the aqueous ink. The fixing agent in the present invention can fix (aggregate) water-based ink by contacting with water-based ink on paper. For example, by applying an aqueous treatment liquid, when the aqueous ink is deposited and contacted in the state where the fixing agent is present on the paper, the components in the aqueous ink can be aggregated and immobilized on the paper. it can.

  Since it is desirable that the water-based ink can be fixed (aggregated), it is preferable that the material be easily dissolved in the water-based ink when coming into contact with the water-based ink. In this respect, the highly water-soluble polyvalent metal salt is more An acidic substance having a high water solubility is more preferable. Further, from the viewpoint of fixing the entire ink by reacting with the aqueous ink, an acidic substance having a valence of 2 or more is particularly preferable. Moreover, a cationic compound can also be used as a fixing agent.

  Here, the aggregation reaction of the water-based ink can be achieved by reducing the dispersion stability of particles dispersed in the water-based ink (colorant (for example, pigment), resin particles, etc.) and increasing the viscosity of the entire ink. it can. For example, the surface charge of particles such as pigments and resin particles in inks that are dispersed and stabilized with weakly acidic functional groups such as carboxyl groups is reduced by reacting with acidic substances having a lower pKa, thereby reducing dispersion stability. can do. Therefore, the acidic substance as a fixing agent contained in the aqueous treatment liquid preferably has a low pKa, a high solubility, and a valence of 2 or more, and a functional group that stabilizes the dispersion of particles in the ink. More preferably, it is a divalent or trivalent acidic substance having a high buffering capacity in a pH range lower than the pKa (for example, carboxyl group).

  Specific examples include phosphoric acid, oxalic acid, malonic acid, succinic acid, citric acid, and phthalic acid. In addition, other acidic substances having pKa and solubility similar to these can be used.

  Among these acidic substances, citric acid is preferably used in a system that has a high water retention ability and tends to increase the physical strength of the aggregated ink, and requires more mechanical properties. On the other hand, malonic acid is preferably used when the water retention is low and it is desired to speed up drying of the treatment liquid.

  As described above, the fixing agent can be appropriately selected and used depending on a secondary factor different from the fixing ability of the water-based ink.

  Examples of the polyvalent metal salt include alkaline earth metals belonging to Group 2 of the periodic table (eg, magnesium, calcium), transition metals belonging to Group 3 of the periodic table (eg, lanthanum), and Group 13 of the periodic table. Mention may be made of salts of cations (for example, aluminum) and lanthanides (for example, neodymium).

  Preferred examples of the cationic compound include cationic surfactants. As the cationic surfactant, for example, a primary, secondary, or tertiary amine salt type compound is preferable. In addition, amphoteric surfactants that are cationic in the desired pH range can also be used.

  The said fixing agent can be used individually by 1 type or in mixture of 2 or more types.

  The content of the fixing agent for fixing the water-based ink in the aqueous treatment liquid is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, and still more preferably 10 to 25% by mass. is there.

  The aqueous treatment liquid in the present invention can generally contain a water-soluble organic solvent in addition to the fixing agent, and can be constituted by using various other additives in the same manner as the water-based ink.

  As the water-soluble organic solvent, it is preferable to add a water-soluble solvent having an SP value of 27.5 or less for the purpose of suppressing curling similarly to the water-based ink.

  In addition, said organic solvent may be used independently and may use 2 or more types together. Moreover, it is preferable that these organic solvents are contained 1-50 mass% in a process liquid.

  The amount of the fixing agent applied is not particularly limited as long as it is an amount sufficient to stabilize the water-based ink, and is preferably 0.25 g / m 2 or more, and is 0 in that the water-based ink is easily fixed by aggregation. More preferably, it is not less than 30 g / m 2 and less than 2.0 g / m 2, and still more preferably not less than 0.40 g / m 2 and less than 1.0 g / m 2.

  The surface tension (25 ° C.) of the aqueous treatment liquid is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 25 mN / m or less and 50 mN / m or less, More preferably, it is 25 mN / m or more and 45 mN / m or less.

  The surface tension is measured using an automatic surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) and a water-based ink at 25 ° C.

  Further, the viscosity of the aqueous treatment liquid at 25 ° C. is preferably 1.2 mPa · s or more and 15.0 mPa · s or less from the viewpoint of stably applying in the range of 0.5 to 3.5 ml / m 2. More preferably, it is 2 mPa * s or more and 12 mPa * s or less, More preferably, it is 2 mPa * s or more and 8 mPa * s or less. In particular, when the aqueous treatment liquid is applied on paper, the viscosity (25 ° C.) is preferably 2 to 8 mPa · s, and more preferably 2 to 6 mPa · s.

  The viscosity is measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD) under an aqueous treatment solution at 25 ° C.

[Evaluation experiment]
Next, an evaluation experiment related to the present invention will be described.

  The composition of the treatment liquid and ink used in this evaluation experiment is shown below.

(Synthesis of resin dispersant P-1)
According to the following scheme, a resin dispersant P-1 (Chemical Formula 8), which is one embodiment of the resin dispersant (A), was synthesized.

  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 in which 10 g of methacrylic acid and 30 g of methyl methacrylate were dissolved was dropped over 3 hours. After the completion of the dropwise addition, the reaction was further continued 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 dispersant P-1 was confirmed by 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.

(Synthesis of self-dispersing polymer fine particles B-01)
According to the following scheme, self-dispersing polymer fine particles B-01, which is one embodiment of the self-dispersing polymer fine particles (C), were synthesized.

  That is, 360.0 g of methyl ethyl ketone was charged into a reaction vessel formed of a 2 liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, and the temperature was raised to 75 ° C.

  Next, 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” (Wako Pure Chemical Industries, Ltd.) (Manufactured) A mixed solution consisting of 1.44 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, and the acid value was 38.9 (mgKOH / g). The weight average molecular weight (Mw) was calculated in terms of polystyrene by gel permeation chromatography (GPC). The columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ200 (manufactured by Tosoh Corporation).

  Next, 668.3 g of the copolymer 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. As a result, an aqueous dispersion (emulsion) of self-dispersing polymer fine particles (B-01) having a solid content concentration of 28.0% was obtained.

  The chemical structural formula of self-dispersing polymer fine particles B-01 is shown below. The number of each structural unit represents a mass ratio.

(Creation of dispersion of cyan pigment-containing resin particles)
CI Pigment Blue 15: 3 (Phthalocyanine-A220 manufactured by Dainichi Seika Co., Ltd.), 5 parts by mass of the resin dispersant (P-1) shown in Table 1, 42 parts by mass of methyl ethyl ketone, and 1 N aqueous NaOH solution 5.8 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 cyan pigment-containing resin particles having a pigment concentration of 10.2% by mass.

(Making a dispersion of magenta pigment-containing resin particles)
Pigment Blue 15: 3 (phthalocyanine blu-A220 manufactured by Dainichi Seika Co., Ltd.) used in the preparation of the cyan pigment dispersion was replaced with Cromophtal Jet Magenta DMQ (PR-122) manufactured by Ciba Specialty Chemicals. In a similar procedure, a dispersion of magenta pigment-containing resin particles was obtained.

(Ink composition)
Magenta ink M1 and cyan inks C1 to C6 were prepared with the following compositions using the dispersion of resin dispersant P-1, self-dispersing polymer fine particles B-01, and cyan pigment-containing resin particles.

(Production of magenta ink)
Dispersion of magenta pigment-containing resin particles 39.2 parts by mass Aqueous dispersion of self-dispersing polymer fine particles (B-01) 28.6 parts by mass Trioxypropylene glyceryl ether (Sanix GP250 (manufactured by Sanyo Chemical Industries, Ltd.)) 15.0 parts by mass Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1.0 part by weight ion-exchanged water balance (preparation of cyan ink)
Dispersion of cyan pigment-containing resin particles 39.2 parts by mass Self-dispersing polymer fine particles (B-01) in water 28.6 parts by mass of trioxypropylene glyceryl ether (Sanix GP250 (manufactured by Sanyo Chemical Industries, Ltd.)) 15.0 parts by mass Olfine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) 1.0 parts by mass ion-exchanged water balance The recording medium used in this evaluation experiment is shown below.

Recording medium A: “Special diamond art paper (basis weight 104 g / m ² )” manufactured by Mitsubishi Paper Industries
Recording medium B: “New Age (basis weight 104 g / m ² )” manufactured by Oji Paper Co., Ltd.
In this evaluation experiment, the case where the treatment liquid was applied / not applied to each of the two types of recording media A and B was evaluated using a system equivalent to the ink jet recording apparatus 1 described in FIG. Further, in the case of applying the treatment liquid, the case where the drying conditions of the treatment liquid and the temperature of the recording medium were changed was also evaluated. The dry strength of the treatment liquid is Lv. 1, Lv. 2, Lv. It becomes higher in order of 3.

  Evaluation methods and criteria for each evaluation item are shown below.

(1) Dot Diameter After a 2.5 pl magenta ink droplet was ejected from an inkjet head into a 150 dpi grid, the ink dot diameter was measured. The ink dot diameter was measured using a dot analyzer DA-6000 manufactured by Oji Scientific Instruments. In addition, about 20 ink dots were measured, and the average value was taken as the ink dot diameter.

(2) Bleeding When 1200 dpi magenta ink line is printed at a speed of 24 kHz with a single pass using the ink jet head used in (1) above, uneven line width, line breakage, and liquid accumulation are observed. X, and other than that is marked with ○.

(3) Color material floating In the image formed in (1) above, a case where the average deviation amount of the inter-dot distance is 5% or more (that is, 8.5 μm or more) × less than 5% (that is, 8.5 μm) Less than).

(4) Fixing offset Droplet density: 1200 dpi × 1200 dpi, droplet ejection amount (ejection amount): After ejecting ink droplets of each color in the order of magenta and cyan under the droplet ejection condition of 4 pl, the ink on the recording medium Then, drying is performed until the solvent component (residual water amount) of the treatment liquid becomes approximately 3 g / m ² , and a roller member (heating roller) made of silicon rubber having a surface material of 30 degrees hardness is set to 0.3 MPa at a temperature of 75 ° C. The image forming surface of the recording medium was brought into contact with pressure. When the roller member is brought into contact, the color material does not adhere to the roller member, and the image forming surface does not deteriorate. ○, the color material adheres to the roller member, but the image forming surface does not deteriorate. Δ, a case where a color material adhered to the roller member and deterioration was observed on the image forming surface was rated as x.

  The evaluation results of this evaluation experiment are shown in FIGS. FIG. 10 is a table showing the evaluation results for the recording medium A, and FIG. 11 is a graph showing the relationship between the remaining amount of processing liquid and the ink dot diameter in FIG. FIG. 12 is a table showing the evaluation results for the recording medium B, and FIG. 13 is a graph showing the relationship between the remaining amount of processing liquid and the ink dot diameter in FIG.

  As shown in FIG. 10 and FIG. 12, when the treatment liquid was not applied (Comparative Examples 1 and 4), liquid pools were observed in some places on the line, and the evaluation of “bleeding” was x. Further, at the time of image fixing, the color material adhered to the roller member, the image forming surface was also deteriorated, and the “fixing offset” was evaluated as “x”. In addition, when drying is not performed after applying the treatment liquid (Comparative Examples 2, 3, 5, 6), the movement of dots accompanying the color material floating is recognized, and the evaluation of “color material floating” is x. It was. As described above, in Comparative Examples 1 to 6, deterioration in image quality was confirmed.

  On the other hand, when the treatment liquid is dried after the treatment liquid is applied and before the ink droplet is ejected (Examples 1 to 12), “bleeding”, “coloring material floating”, Each of the evaluation items of “fixing offset” is “◯”, and it is possible to effectively prevent the deterioration of the image quality.

  As can be seen from FIGS. 11 and 13, the ink dot diameter increases in proportion to the remaining amount of the processing liquid, and the ink dot diameter is controlled by changing the drying condition (drying strength) of the processing liquid. Is possible. That is, when recording at high resolution as in the high image quality mode, the ink dot diameter can be reduced by increasing the drying strength and reducing the remaining amount of the processing liquid. On the other hand, when recording at low resolution as in the high-speed mode, the ink dot diameter can be increased by reducing the drying strength and increasing the remaining amount of the processing liquid.

Further, as can be seen from a comparison between Examples 1 to 3 and Examples 4 to 6 (or Examples 7 to 9 and Examples 10 to 12), the type of the recording medium and the treatment liquid drying conditions are the same. The remaining amount of the processing liquid varies depending on the medium temperature. For example, the remaining amount of the processing liquid is 2.1 [g / m ² ] in Example 2 where the medium temperature is 25 ° C., whereas in Example 5 where the medium temperature is 40 ° C., 1. 9 [g / m ² ]. As described above, even when the recording medium type and the treatment liquid drying conditions are the same, the remaining amount of the treatment liquid decreases as the medium temperature increases, and the ink dot diameter decreases. Therefore, the ink dot diameter can be controlled with higher accuracy by selecting the treatment liquid drying conditions according to the temperature of the recording medium.

Further, as can be seen by comparing Examples 1 to 3 and Examples 7 to 9 (or Examples 4 to 6 and Examples 10 to 12), even if the temperature of the recording medium and the treatment liquid drying conditions are the same. The remaining amount of the processing liquid varies depending on the type of the recording medium. For example, the remaining amount of the processing liquid is 1.7 [g / m ² ] in Example 3 using the recording medium A, whereas 2.0 [2.0] in Example 9 using the recording medium B. g / m ² ]. As described above, even when the temperature of the recording medium and the processing liquid drying conditions are the same, the remaining amount of the processing liquid varies depending on the type of the recording medium, and the ink dot diameter changes accordingly. Therefore, the ink dot diameter can be controlled with higher accuracy by selecting the treatment liquid drying conditions according to the type of the recording medium.

  According to the ink jet recording apparatus 1 of the present embodiment, since the drying process of the treatment liquid is performed after the treatment liquid is applied onto the recording medium 22 and before the ink droplet is ejected, the image deterioration due to the color material floating is prevented. In addition, the ink dot diameter can be controlled with high accuracy by controlling the drying of the treatment liquid according to the treatment liquid drying conditions (dry strength) selected according to the recording mode (that is, the image resolution). it can. As a result, it is possible to improve the image quality.

  Further, in the present embodiment, an aspect in which the treatment liquid drying conditions are selected according to the type or temperature (more preferably both) of the recording medium is preferable, and it is not affected by the type of the recording medium or the medium temperature. The ink dot diameter can be controlled with higher accuracy.

[Other configuration examples of inkjet recording apparatus]
The inkjet recording apparatus 1 described above is an example in which the recording medium 22 is conveyed by a drum, but may be conveyed by a belt. FIG. 14 schematically shows the configuration of the belt conveyance type inkjet recording apparatus 2. In addition, the same code | symbol is attached | subjected about the component same or similar to the inkjet recording device 1 shown in FIG. 1, and the description is abbreviate | omitted.

  The ink jet recording apparatus 2 shown in FIG. 14 mainly includes a processing liquid application unit 12, a drawing unit 14, a drying unit 16, and a fixing unit 18, and the recording medium 22 is conveyed by the suction belt conveyance device 200.

  The suction belt conveyance device 200 includes a pair of rollers 202 and an endless belt 204 wound around the rollers 202, and at least one of the pair of rollers 202 is rotationally driven by a motor or the like (not shown). As a result, the belt 204 travels between the pair of rollers 202.

  The belt 204 has a width wider than that of the recording medium 22, and a plurality of suction ports (not shown) are formed on the upper surface of the belt 204. An adsorption chamber (not shown) is provided inside the belt 204. The adsorption chamber is provided at a position facing the processing liquid application unit 12 and the drawing unit 14, and the suction chamber is sucked with a pump (not shown) or the like to make a negative pressure, thereby recording medium 22 on belt 204. Can be adsorbed and held.

  Although a mechanism using a nip conveyance mechanism with a roller may be used in place of the suction belt conveyance device 200, if the nip conveyance is performed in the printing area, the roller is brought into contact with the printing surface of the sheet immediately after printing, so that the image is easily stained. There's a problem. Therefore, as in this example, suction belt conveyance that does not bring the image surface into contact with each other in the print region is preferable.

  By the suction belt conveyance device 200 described above, the recording medium 22 is conveyed from the paper supply unit (not shown) to the treatment liquid application unit 12. The processing liquid application unit 12 includes a nozzle-shaped recording head 206 and is configured to discharge the processing liquid from the recording head 206 toward the recording medium 22. As a result, the treatment liquid is applied to the recording medium 22 to form a treatment liquid layer. The treatment liquid application unit 12 is not limited to the method of discharging from the nozzle-shaped recording head 206, and an application method using an application roller can also be adopted.

  The recording medium 22 to which the treatment liquid is applied is heated by a hot air supply device 208 that supplies hot air to the upper surface of the recording medium 22 and a heating panel 210 disposed below the recording medium 22. The heating temperature at that time is preferably a temperature equal to or higher than the softening point temperature of the solid particles or a temperature equal to or higher than the melting point temperature.

  The recording medium 22 subjected to the drying process is sent to the drawing unit 14, and ink is ejected from each of the inkjet heads 72M, 72C, 72Y, 72K. The ink jet heads 72M, 72C, 72Y, and 72K are arranged so as to eject ink in ascending order of surface tension, as in the case of the ink jet recording apparatus 1 of FIG.

  A drying unit 16 is provided following the drawing unit 14. The drying unit 16 is a device that removes a solvent component remaining on the recording medium 22 on which each color ink is ejected. A hot air supply device 212 that supplies hot air to the upper surface of the recording medium 22, and a lower part of the recording medium 22. A heating panel 214 is provided. The solvent on the recording medium 22 is removed by the drying unit 16.

  A fixing unit 18 is provided following the drying unit 16. The fixing unit 18 includes fixing rollers 216 and 218 arranged with the recording medium 22 interposed therebetween. By pressing and heating with the fixing rollers 216 and 218, an image on the recording medium 22 is recorded. To be established.

14 includes a medium type detection unit 230 that detects the type of the recording medium 22 and a medium temperature detection unit 232 that detects the temperature of the recording medium 22. The positions of the detection means 230 and 232 are not particularly limited, but the medium temperature detection means 232 is preferably located at a position adjacent to the downstream side in the sub-scanning direction with respect to the hot air supply device 208 of the treatment liquid application unit 12. Be placed. The type and temperature of the recording medium 22 detected by each of the detection means 230 and 232 are notified to the system controller 122 (see FIG. 6), and the system controller 122 dries the processing liquid according to the type and temperature of the recording medium 22. The processing liquid drying means (hot air supply device 208, heating panel 210) is controlled according to the conditions. Thereby, the ink dot diameter can be controlled with higher accuracy without being influenced by the type and temperature of the recording medium 22.
The image forming method and the image forming apparatus of the present invention have been described in detail above. However, the present invention is not limited to the above examples, and various improvements and modifications are made without departing from the gist of the present invention. Of course it is also good.

Schematic configuration diagram showing an inkjet recording apparatus of the present embodiment Plane perspective view showing structural example of head Plan view showing another structural example of the head Sectional view showing the three-dimensional configuration of the ink chamber unit Plan view showing an example of nozzle arrangement of the head Main block diagram showing the system configuration of the inkjet recording apparatus Flow chart showing treatment liquid drying control The figure which showed an example of the dot diameter information table The figure which showed an example of the recording mode table which showed the correspondence of recording mode and dot diameter Table showing evaluation results for recording medium A 10 is a graph showing the relationship between the remaining amount of processing liquid and the ink dot diameter in FIG. Table showing evaluation results for recording medium B 12 is a graph showing the relationship between the remaining amount of processing liquid and the ink dot diameter in FIG. Schematic configuration diagram showing another configuration example of the inkjet recording apparatus

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Paper feed part, 12 ... Processing liquid provision part, 14 ... Drawing part, 16 ... Drying part, 18 ... Fixing part, 20 ... Discharge part, 22 ... Recording medium, 24 ... 1st middle Conveying section, 26 ... second intermediate conveying section, 28 ... third intermediate conveying section, 30 ... intermediate conveying body, 70 ... drawing drum, 72M, 72C, 72Y, 72K ... ink jet head, 76 ... drying drum, 84 ... Fixing drum, 86 ... first fixing roller, 88 ... second fixing roller

Claims (6)

A recording mode determining step for determining an arbitrary recording mode from among a plurality of recording modes;
A treatment liquid application step for applying a treatment liquid containing a component that reacts with ink to the recording medium;
A treatment liquid drying condition selection step for selecting a treatment liquid drying condition according to the recording mode determined in the recording mode determination step from a plurality of treatment liquid drying conditions;
A treatment liquid drying step of drying the treatment liquid applied on the recording medium according to the treatment liquid drying conditions selected in the treatment liquid drying condition selection step;
After the treatment liquid drying step is performed, based on the input image data and the recording mode determined in the recording mode determination step, an ink droplet ejection step of ejecting ink droplets on the recording medium;
Only including,
Among a plurality of recording modes having different droplet ejection densities, the droplet ejection density in the first recording mode is larger than the droplet ejection density in the second recording mode, and the first recording mode is set in the treatment liquid drying condition selection step. The first processing liquid drying condition selected in accordance with the second processing liquid drying condition selected in accordance with the second recording mode has a larger amount of drying of the processing liquid than the second processing liquid drying condition selected in accordance with the second recording mode. Method. The image forming method according to claim 1,
2. The image forming method according to claim 1, wherein the plurality of recording modes have different droplet ejection densities, and the amount of droplets when ink droplets are ejected according to each recording mode is substantially the same. The image forming method according to claim 1 or 2 ,
An image forming method, further comprising an image fixing step of fixing an image formed on the recording medium while being pressed by a heating member. The image forming method according to any one of claims 1 to 3 ,
A medium temperature detecting step for detecting the temperature of the recording medium;
In the image forming method, the processing liquid drying condition selection step selects a processing liquid drying condition according to the temperature of the recording medium detected in the medium temperature detection step. The image forming method according to any one of claims 1 to 4,
A medium type detecting step of detecting the type of the recording medium,
In the image forming method, the processing liquid drying condition selection step determines processing liquid drying conditions according to the type of the recording medium detected in the medium type detection step. A recording mode determining means for determining an arbitrary recording mode from a plurality of recording modes;
Treatment liquid application means for applying a treatment liquid containing a component that reacts with ink to the recording medium;
A treatment liquid drying condition selection means for selecting a treatment liquid drying condition according to the recording mode determined by the recording mode determination means from a plurality of treatment liquid drying conditions;
Processing liquid drying means for drying the processing liquid applied on the recording medium according to the processing liquid drying conditions selected by the processing liquid drying condition selection means;
After the treatment liquid applied on the recording medium is dried, ink droplets are ejected onto the recording medium based on the input image data and the recording mode determined by the recording mode determining means. Ink droplet ejection means;
Equipped with a,
Among a plurality of recording modes having different droplet ejection densities, the droplet ejection density in the first recording mode is larger than the droplet ejection density in the second recording mode, and the processing liquid drying condition selection unit switches to the first recording mode. The first processing liquid drying condition selected in accordance with the second processing liquid drying condition selected in accordance with the second recording mode has a larger amount of drying of the processing liquid than the second processing liquid drying condition selected in accordance with the second recording mode. apparatus.

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