JP2009166353A - Inkjet device and preliminary ejection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet device and a preliminary ejection method by which visibility of dots due to preliminary ejection can be lowered. <P>SOLUTION: The inkjet device 101 includes a head unit 110 which ejects an ink to paper 114, and a roller 136 which performs preprocessing of the paper 114 with colorless or light color processing solution 135 before the ink is ejected to the paper 114. The head unit 110 can preliminarily eject the ink to the paper 114. The roller 136 can perform preprocessing of an area of the paper 114 to which the ink is preliminarily ejected with the processing solution 135 before the ink is preliminarily ejected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet apparatus and a preliminary discharge method.

  An ink jet apparatus can form an image on a recording medium in a non-contact manner by ejecting ink droplets from a large number of pores called nozzles, and is not limited by the type or shape of the recording medium. An image can be formed by one image forming process. The nozzle has a fine orifice having a diameter of 50 μm or less, and ejects ink droplets from the orifice, so that it is very difficult to keep the nozzle in a normal state. The inkjet head has a huge number of nozzles of several hundred to several thousand, so it is in a defective discharge state (a state where it cannot be discharged from the nozzle, a state where it is not discharged in a direction substantially perpendicular to the nozzle surface), and a discharged droplet has a desired size. It is important to avoid a state in which a film cannot be formed and to maintain a normal state.

  Since the orifice is exposed to the air when forming an image, the ink dries, and changes such as changes in viscosity, ink composition, and increase in coarse particles occur. Further, when the paper is transported directly under the inkjet head when forming an image, a component (paper dust) peeled off from the paper may adhere to the orifice. For this reason, in order to avoid an ejection failure state, the ink in the orifice is kept fresh by periodically performing preliminary ejection and discharging the ink in the orifice that has not been ejected for a predetermined period. ing.

  In recent years, pigment dispersions and resins have been added to inks for the purpose of improving weather resistance and color developability and improving the degree of freedom with respect to recording media. As a result, changes in physical properties due to ink drying increase, and the frequency of preliminary ejection needs to be improved.

  On the other hand, it is required to improve productivity, and it is required to reduce preliminary discharge. When preliminary ejection is performed, the inkjet head is moved to a position for preliminary ejection and ejection is performed, so productivity is lowered.

  For this reason, as a method of performing preliminary ejection while improving productivity, a method of performing preliminary ejection while forming an image on a recording medium is known. For example, Patent Document 1 discloses an ink jet recording apparatus that performs preliminary ejection that does not contribute to recording. The ink jet recording apparatus is a recording apparatus in which the amount of ink discharged changes according to the time during which recording is not performed. Preliminary discharge is performed using a region where the discharge amount is lower than the steady discharge amount.

On the other hand, as a method for improving the image quality of an ink jet apparatus, a method of preprocessing a recording medium is known. However, when preliminary ejection is performed on the recording medium, there is a problem that the preliminary ejection dots are conspicuous due to the characteristics of the recording medium and the physical properties of the ink, and the quality of the formed image is deteriorated.
JP 2002-144599 A

  An object of the present invention is to provide an ink jet apparatus and a preliminary ejection method capable of reducing the visibility of dots by preliminary ejection in view of the problems of the above-described conventional technology.

  According to a first aspect of the present invention, there is provided an ejection unit for ejecting ink onto a recording medium, and the recording medium is pretreated with a colorless or light-colored processing liquid before the ink is ejected onto the recording medium. An ink jet apparatus having pre-processing means, wherein the ejection means can pre-discharge the ink onto the recording medium, and the pre-processing means can perform the recording before the preliminary ejection. It is characterized in that it is possible to pre-process the pre-discharge area of the medium with the processing liquid.

  According to a second aspect of the present invention, in the ink jet apparatus according to the first aspect, the ejection unit can eject the ink onto the recording medium to form an image in which dots do not overlap, The preprocessing means is capable of preprocessing an area including a part of an area where an image on which dots of the recording medium do not overlap with each other is formed with the processing liquid.

  According to a third aspect of the present invention, in the ink jet apparatus according to the first or second aspect, the treatment liquid contains at least one of a polyvalent metal salt, a cationic resin, a cationic particle, and an organic acid, and a surfactant. It is characterized by including.

  According to a fourth aspect of the present invention, in the ink jet apparatus according to any one of the first to third aspects, a pigment or a colored resin is dispersed in the ink.

  According to a fifth aspect of the present invention, there is provided a preliminary ejection method in which preliminary ejection is performed using the ink jet apparatus according to any one of the first to fourth aspects, wherein the preprocessing unit is configured to perform preliminary ejection of the recording medium. And a step of pre-discharging the ink in the pre-processed region of the recording medium.

  According to a sixth aspect of the present invention, in the preliminary ejection method according to the fifth aspect, the ink is preliminarily reserved on the recording medium in the case where the preprocessing is performed than in the case where the preprocessing is not performed. When the density of the image formed by the ejection is low, the pretreatment means pretreats the preliminary ejection area of the recording medium with the treatment liquid.

  According to the present invention, it is possible to provide an ink jet apparatus and a preliminary ejection method capable of reducing the visibility of dots by preliminary ejection.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  An ink jet apparatus according to the present invention includes an ejection unit that ejects ink onto a recording medium, and a pretreatment unit that pretreats the recording medium with a colorless or light-colored processing liquid before the ink is ejected onto the recording medium. . At this time, the ejection means can preliminarily eject ink onto the recording medium, and the pretreatment means pretreats the area to be preliminarily ejected on the recording medium with the treatment liquid before the preliminary ejection. It is possible. Thereby, the visibility of the dot by preliminary discharge can be reduced.

  When the inkjet apparatus of the present invention is used, an image can be formed on a recording medium by ejecting ink after pre-processing the recording medium with a processing liquid. The treatment liquid and the ink come into contact with each other on the recording medium and cause a chemical reaction or interaction. Such a chemical reaction or interaction causes the colorant in the ink to be insolubilized or aggregated, or the ink physical properties such as viscosity and permeability are changed. As a result, it is possible to fix the ink on the surface layer of the recording medium and improve the color development of the image. Moreover, mixing with bleed or other inks can be suppressed by reducing the fluidity of the colorant in the ink.

  Such an effect is based on a chemical reaction or interaction between the treatment liquid and the ink, but the degree of the effect varies depending on the recording medium. When a recording medium having high ink absorbability and small interaction with the colorant in the ink is used, the ink is absorbed into the recording medium, and the ratio of the colorant remaining on the surface layer of the recording medium decreases. When such a recording medium is pretreated with the processing liquid, the colorant is fixed on the surface layer of the recording medium, and the image quality is improved. At this time, since the colorant is present in the surface layer portion of the recording medium, the visibility of the dots is improved.

  On the other hand, when a recording medium having low ink absorbability is used, the ink is fixed on the surface of the recording medium, so that the colorant in the ink is fixed on the surface layer of the recording medium. Further, when a recording medium having high ink absorbability and large interaction with the colorant in the ink is used, the colorant is trapped on the surface layer of the recording medium and fixed. When such a recording medium is pretreated with the processing liquid, the colorant is trapped on the surface layer of the recording medium, so that the flowability of the coloring agent is reduced, and the dot diameter of the ink is reduced. The visibility of dots is lower than that of a recording medium that has not been preprocessed.

  On the other hand, when ink is preliminarily ejected onto the recording medium, it is preferable that the dots formed by the preliminarily ejected ink droplets have low visibility so as not to disturb the formed image. In the present invention, by utilizing the phenomenon as described above, pretreatment with a treatment liquid according to a recording medium can reduce dot visibility by preliminary ejection and improve image quality. it can.

  FIG. 1 shows a line head inkjet device as an example of the inkjet device of the present invention. The ink jet apparatus 101 includes head units 110K, 110C, 110M, and 110Y each including a head that ejects ink of each color of black (K), cyan (C), magenta (M), and yellow (Y), and head units of each color. Maintenance units 111K, 111C, 111M, and 111Y that perform maintenance of 110 heads are provided. In addition, cartridges 107K, 107C, 107M, and 107Y that store ink supplied to the heads of the head units 110 of the respective colors can be detachably mounted on the main body of the inkjet apparatus 101. Further, the inkjet apparatus 101 includes sub tanks 108K, 108C, 108M, and 108Y that store a part of the ink supplied from the cartridges 107 of each color and supply the ink to the head at a predetermined pressure. Ink is supplied from the cartridge 107 to the sub tank 108 via a tube (not shown) by driving an ink supply motor (not shown). Further, the maintenance unit 111 is moved by driving a maintenance unit moving motor (not shown), and the head is maintained.

  FIG. 2 shows the head unit 110 for each color. In the head unit 110, the heads 154A to 154L are fixed to the outer peripheral member 160, and the heads 154A to 154L are fixed in a two-row staggered arrangement so that a part of the nozzle rows overlap. As shown in FIG. 3, each head 154 is provided with a nozzle row 200 that is opened in two rows in a staggered arrangement on the nozzle plate 201. The nozzle row 200 is arranged so as to be orthogonal to the conveyance direction of the paper 114, and its length is equal to or longer than the recording area. Further, a filler 202 is filled between each head 154 and the outer peripheral member 160 and is sealed.

  The head 154 has pressure generating means for pressurizing and discharging the ink in the ink flow path, but the pressure generating means is not particularly limited, and a vibration plate that forms the wall surface of the ink flow path using a piezoelectric element. A piezo type that deforms and changes the volume in the ink flow path to eject ink (see Japanese Patent Laid-Open No. 2-51734), and heats the ink in the ink flow path using a heating resistor to create bubbles. Thermal type to be generated (see Japanese Patent Application Laid-Open No. 61-59911), the diaphragm and the electrode forming the wall surface of the ink flow path are opposed to each other, and the diaphragm is generated by the electrostatic force generated between the diaphragm and the electrode. An electrostatic type (see Japanese Patent Application Laid-Open No. 6-71882) that discharges ink droplets by changing the volume in the ink flow path can be cited.

  Further, the inkjet apparatus 101 includes a transport mechanism that transports the paper 114, a paper discharge mechanism that discharges the paper 114, and a paper feed mechanism that feeds the paper 114. The transport mechanism is configured so that the transport belt 113 that sucks and transports the paper 114, the transport rollers 119 and 121 that rotate the transport belt 113 by driving a transport roller rotation motor (not shown), and the transport belt 113 maintain a predetermined tension. A tension roller 115 to be controlled, a platen 124 for the conveyor belt 113 to maintain a predetermined flatness, and a charging roller 118 for charging the conveyor belt 113 to attract the paper 114. Further, the paper discharge mechanism stocks the separation claw 120 that separates the paper 114 from the transport belt 113, the paper discharge roller 116 that discharges the paper 114, the paper discharge roller 117 that holds the paper 114, and the discharged paper 114. A paper discharge tray 104 is provided. Further, the paper feed mechanism includes paper feed trays 103a and 103b for stocking the paper 114, separation rollers 112a and 112b for feeding the paper 114 one by one from the paper feed tray 103, and the transported paper 113 to the charged transport belt 113. It comprises a counter roller 123 to be sucked, a pressing member 122 for pressing the paper 114, and a manual feed tray 105 used when the paper 114 is fed manually.

  The ink jet apparatus 101 can display a waste liquid tank 109 that collects waste liquid discharged after the maintenance unit 111 of each color performs head maintenance, and a user can operate the ink jet apparatus 101 to display the state of the apparatus. An operation panel 106 is also provided.

  Next, an operation for printing on the paper 114 using the inkjet apparatus 101 will be described. When the paper 114 is not preprocessed, the paper 114 is sent out one by one by the separation roller 112a from the paper feed tray 103a and then fixed by being brought into close contact with the conveyor belt 113 by the counter roller 123. Next, when the paper 114 passes under the head unit 110 of each color, ink of each color is ejected onto the paper 114, and an image is formed on the paper 114. Further, the sheet 114 on which the image is formed is separated from the conveying belt 113 by the separation claw 120 and discharged to the discharge tray 104 by the discharge roller 116 and the discharge roller 117.

  On the other hand, when the paper 114 is pre-processed, the paper 114 is fed one by one from the paper feed tray 103b by the separation roller 112b, and then the processing liquid 135 is applied onto the paper 114 by the roller 136. Specifically, the processing liquid 135 is pumped onto the surface of the roller 137 by driving a roller group rotation motor (not shown), and is sequentially transferred to the roller 138 and the roller 136, and then between the roller 136 and the counter roller 139. It is transferred to the paper 114. At this time, the processing liquid 135 is supplied from the cartridge 140 via a tube (not shown) by driving a processing liquid supply roller (not shown). Thereafter, an image is formed on the paper 114 in the same manner as described above.

  At this time, since the amount of the processing liquid 135 transferred to the roller 136 is controlled by controlling the nip thickness between the roller 138 and the roller 136, the coating amount of the processing liquid 135 can be controlled. Furthermore, the processing liquid 135 on the surface of the roller 136 can be scraped off by pressing the movable blade 134 against the roller 136 so that the processing liquid 135 does not remain on the roller 136. As a result, it is possible to suppress the occurrence of coating unevenness due to the drying and thickening of the processing liquid 135 or the fixing of the processing liquid 135 to the counter roller 139.

  Note that the coating method of the treatment liquid 135 is not limited to roller coating, and methods such as spray coating and sublimation coating may be used. Further, by providing a head unit that discharges the treatment liquid 135, the treatment liquid 135 and the ink can be applied by inkjet in the same process, and the application amount and application position can be easily controlled with high accuracy.

  4 and 5 show a serial ink jet device as another example of the ink jet device of the present invention. 4 and 5, the same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The ink jet apparatus 102 holds a carriage 131 slidably in a main scanning direction by a guide rod 130 and a stay 133 that are horizontally mounted on two side plates (not shown), and is moved by a carriage moving motor (not shown). Scan.

  On the carriage 131, four head units 110 that discharge inks of yellow, cyan, magenta, and black are arranged so that nozzle rows are arranged in the conveyance direction of the paper 114 and the ink is discharged downward. Yes. In addition, the carriage 131 is equipped with a sub tank 108 for each color for supplying ink of each color to the head unit 110. Ink is supplied from a cartridge (not shown) to the sub tank 108 via a tube (not shown) by driving an ink supply motor (not shown).

  A duplex unit 132 is detachably mounted on the back surface of the inkjet apparatus 102. The duplex unit 132 takes in the paper 114 returned by the reverse rotation of the transport belt 113, reverses it, and feeds it again between the counter roller 123 and the transport belt 113. A manual feed tray 105 is provided on the upper surface of the duplex unit 132.

  When the inkjet apparatus 102 is used, a carriage movement motor (not shown) scans the carriage 131 according to intermittent paper conveyance, and the head unit 110 ejects ink, thereby forming an image on the paper 114. Can do.

  Although FIG. 4 and FIG. 5 do not show pre-processing means for pre-processing the paper 114 with the processing liquid, the ink-jet apparatus 102 can pre-process the paper 114 in the same manner as the ink-jet apparatus 101. it can.

  FIG. 6 shows a control unit of the inkjet apparatus 101. The control unit 300 includes a CPU 301, a ROM 302, a RAM 303, an NVRAM (nonvolatile memory) 304, and an ASIC 305. The CPU 301 controls the entire inkjet apparatus. Further, the ROM 302 stores a program executed by the CPU 301, a value of the degree of contamination of the nozzle surface with respect to predetermined ink ejection, a contamination threshold value of the nozzle surface, driving waveform data of the pressure generating means of the head 154, and other fixed data. To do. Further, the RAM 303 temporarily stores image data and the like. A non-volatile memory (NVRAM) 304 is provided to hold data even while the power supply of the inkjet apparatus is shut off. Further, the ASIC 305 processes image processing for performing various signal processing and rearrangement on the image data, and other input / output signals for controlling the entire inkjet apparatus.

  Further, the control unit 300 includes an I / F 306, a head control unit 307, a paper transport control unit 308, a maintenance control unit 310, an ink supply path control unit 312, an ink supply control unit 314, and a processing liquid application control. A unit 316, a processing liquid supply control unit 318, and an I / O 320. The I / F 306 transmits and receives data and signals to and from the host side. The head control unit 307 creates a drive waveform for driving the pressure generating means of the head 154 and controls the driving of the pressure generating means. Further, the paper conveyance control unit 308 controls driving of a conveyance roller rotation motor 309 that rotates the conveyance rollers 119 and 121. Further, the maintenance control unit 310 controls driving of the maintenance unit moving motor 311. Further, the ink supply path control unit 312 controls the opening and closing of the electromagnetic valve 313 provided in the tube that supplies ink to the sub tank 108. Further, the ink supply control unit 314 controls driving of an ink supply motor 315 that supplies ink to the sub tank 108. Further, the processing liquid application control unit 314 controls driving of a roller group rotation motor 315 that rotates a group of rollers (rollers 136 to 139) for applying the processing liquid 315. Further, the processing liquid supply control unit 316 controls driving of the processing liquid supply motor 317 that supplies the processing liquid 135. Further, the I / O 320 includes an encoder that outputs a detection signal corresponding to the moving amount and moving speed of the conveyor belt 113, a detection signal from the sensor 321 that detects environmental temperature and / or environmental humidity, and ink amount detection of the sub tank 108. Signals and detection signals from various sensors (not shown) are input. The control unit 300 is connected to an operation panel 106 for inputting and displaying information necessary for the ink jet apparatus.

  Next, control of the inkjet apparatus by the control unit 300 will be described. The control unit 300 receives print data and the like from the host side such as an information processing apparatus such as a personal computer, an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera via the cable or the network by the I / F 306. Then, the CPU 301 reads and analyzes the print data in the reception buffer included in the I / F 306, performs necessary image processing, data rearrangement processing, and the like in the ASIC 305, and reduces the head width of each head 154 to one page. The corresponding image data (dot pattern data) is developed. At this time, the font data may be stored in the ROM 302 and expanded into image data, or the printer driver on the host side may expand the print data into bitmap data and transfer it to the I / F 306. Next, the CPU 301 sends image data to the head controller 307 in synchronization with the clock signal. Further, the head control unit 307 selectively drives the pressure generating means (not shown) of the head 154 based on the image data, and discharges ink.

  Further, when the paper 114 is pre-processed with the processing liquid 135, the processing liquid supply control unit 318 drives the roller group rotation motor 315 to rotate the roller group including the rollers 136 to 139, so that the processing liquid 135 is applied to the paper 114. Apply.

  The control unit of the inkjet apparatus 102 further includes a carriage movement motor drive control unit that drives the carriage movement motor.

  FIG. 7 shows a case where the treatment liquid 135 is applied by roller as an example of the printing process performed by the inkjet apparatus 101. First, the inkjet apparatus receives print data from the host side (S1). Next, the print data is developed into image data (S2), the image data is rasterized, and raster data is formed (S3). The raster data is image data printed on the central portion 141 of the paper 114 (see FIG. 8).

  Next, the user inputs whether or not pre-processing is necessary for printing (S4). If pre-processing is necessary, the pre-processing area is calculated from the raster data and determined (S5). Then, the user inputs whether or not pre-processing is necessary for pre-discharge (S6). If pre-processing is necessary, a pre-discharge pattern is added to the raster data (S7) and the pre-discharge area is also added. The preprocessing area is re-determined so as to be preprocessed (S8). If pre-processing is not necessary for pre-discharge, a pre-discharge pattern outside the pre-process area is added to the raster data so as not to pre-discharge to the pre-process area (S9).

  On the other hand, if pre-processing is not necessary for printing, the user inputs whether pre-processing is necessary for pre-discharge (S10). If pre-processing is necessary, pre-processing is performed from the pre-discharge pattern outside the print area. The area is determined (S11), and the preliminary ejection pattern is added to the raster data (S12). If no preprocessing is required for the preliminary ejection, the preliminary ejection pattern is added to the raster data (S13).

  Next, when pre-processing is necessary, the processing liquid 135 is applied by roller to the pre-processing area of the paper 114 (S14), and the pre-processed paper 114 is fed (S15). The paper 114 is printed based on the raster data (S16) and discharged (S17). Further, the presence / absence of print data for the next page is confirmed (S18). If there is print data, the process returns to S2 and is developed into image data. If there is no print data, the print process is terminated.

  FIG. 9 shows a case where the treatment liquid 135 is applied by inkjet as an example of printing processing by the inkjet apparatus 101. First, the inkjet apparatus receives print data from the host side (S1). Next, the print data is developed into image data (S2), and the paper 114 is fed (S3). Further, raster processing is performed on the image data to form raster data (S4). The raster data is image data printed on the central portion 141 of the paper 114 (see FIG. 8).

  Next, the user inputs whether or not pre-processing is necessary for printing (S5). If pre-processing is necessary, the pre-processing area is calculated from the raster data and determined (S6). Then, the user inputs whether or not pre-processing is necessary for preliminary ejection (S7), and if pre-processing is necessary, a preliminary ejection pattern is added to the raster data (S8), and the region to be pre-ejected is also added. The preprocessing area is re-determined so as to be preprocessed (S9). If pre-processing is not necessary for pre-discharge, a pre-discharge pattern outside the pre-process area is added to the raster data so as not to pre-discharge to the pre-process area (S10).

  On the other hand, if pre-processing is unnecessary for printing, the user inputs whether pre-processing is necessary for preliminary ejection (S11). If pre-processing is necessary, pre-processing is performed from the preliminary ejection pattern outside the printing area. The area is determined (S12), and the preliminary ejection pattern is added to the raster data (S13). If no preprocessing is required for preliminary ejection, a preliminary ejection pattern is added to the raster data (S14).

  Next, when the pretreatment is necessary, the treatment liquid 135 is applied to the pretreatment region of the paper 114 by inkjet (S15). The paper 114 is printed based on the raster data (S16) and discharged (S17). Further, the presence / absence of print data for the next page is confirmed (S18). If there is print data, the process returns to S2 and is developed into image data. If there is no print data, the print process is terminated.

  7 and 9, when the preliminary ejection pattern is formed outside the preprocessing area or outside the printing area, the left and right margin portions 142 and the upper and lower margin portions 143 (see FIG. 8) of the paper 114 are used. Can be used. In addition, when the treatment liquid 135 is applied by a roller, it is difficult to control the application of the paper 114 in the width direction. Therefore, it is preferable to form a preliminary discharge pattern in the upper and lower margins 143. The preliminary ejection pattern is preferably formed by applying a blue noise mask or the like so that adjacent pixels are not ejected and a periodic pattern is not formed so as not to be noticeable.

  On the other hand, whether or not pretreatment is necessary for preliminary ejection is determined by ejecting ink under the same conditions on the paper 114 pretreated with the treatment liquid 135 and the paper 114 not pretreated. This is done by forming an image that does not overlap and evaluating the density of the image where the dots do not overlap. At this time, in order to reduce the amount of paper 114 used, it is preferable to form a preprocessed area and a non-preprocessed area on the same paper 114. Specifically, as shown in FIG. 10, by forming images 145 in which dots do not overlap on a paper 114 having a preprocessed area 144 inside and outside the preprocessed area 144, It is possible to evaluate the density of an image in which dots do not overlap due to the presence or absence of preprocessing. As a result, the predischarge region of the paper 114 is preprocessed when the density of an image where dots do not overlap is lower in the case of preprocessing than in the case of no preprocessing. Thereby, the visibility of the dot by preliminary discharge can be reduced and the quality of an image can be improved. The dot density may be evaluated using an optical density measuring device or may be evaluated based on sensory judgment.

  Similarly, whether or not pre-processing is necessary for printing is determined by ejecting ink under the same conditions on the paper 114 pre-processed with the processing liquid 135 and the paper 114 not pre-processed. This is done by forming overlapping images and evaluating the density of the images. At this time, in order to reduce the amount of paper 114 used, it is preferable to form a preprocessed area and a non-preprocessed area on the same paper 114. Specifically, as shown in FIG. 11, yellow, magenta, cyan, and black images 146, 147, 148, and 149 in which dots overlap are pre-processed on a sheet 114 having a pre-processed area 144. By forming it inside and outside the area 144, it is possible to evaluate the image density depending on the presence or absence of preprocessing. As a result, the area to be printed on the paper 114 is preprocessed when the density of the image is higher than when the preprocess is not performed. Thereby, the image quality can be improved. The image density may be evaluated using an optical density measuring device, or may be evaluated based on sensory judgment.

  Also, as shown in FIG. 12, an image 145 in which dots do not overlap and yellow, magenta, cyan, and black images 146, 147, 148, and 149 in which dots overlap are formed on a paper 114 having a preprocessed area 144. Alternatively, it may be formed inside and outside the preprocessed region 144. Thereby, both can be evaluated on the same paper 114, and the usage amount and work amount of the paper 114 can be reduced.

  The recording medium is not limited to paper, and thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, and the like can be used.

  In the present invention, the ink contains a colorant, but is not particularly limited, and may be either water-based ink or oil-based ink. As the colorant, both pigments and dyes can be used, and they may be used in combination. The colorant may be dissolved or dispersed in the ink, or may be dissolved or dispersed in an emulsion or suspension in the ink.

  Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254 289, C.I. I. Acid Blue 9, 29, 45, 92, 249, C.I. I. Acid Black 1, 2, 7, 24, 26, 94, etc .; C.I. I. Food Yellow 2, 3, 4, C.I. I. Food Red 7, 9, 14, C.I. I. Food Black 1, 2, etc. Food Dye; C.I. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 120, 132, 142, 144, 86, C.I. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225, 227, C.I. I. Direct Orange 26, 29, 62, 102, C.I. I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202, C.I. I. Direct black, direct dyes such as 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171; I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 465, 67 70, 73, 77, 87, 91, C.I. I. Basic Red 2, 12, 13, 14, 15, 18, 22, 23, 24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70 73, 78, 82, 102, 104, 109, 112, C.I. I. Basic Blue 1, 3, 5, 7, 9, 21, 22, 26, 35, 41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93 105, 117, 120, 122, 124, 129, 137, 141, 147, 155, C.I. I. B. Basic black 2, 8, etc. basic dyes; I. Reactive Black 3, 4, 7, 11, 12, 17, C.I. I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, 67, C.I. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 60, 66, 74, 79, 96, 97, C.I. I. Reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95 etc. are mentioned, Acid dye and direct dye are preferable. The addition amount of the colorant in the ink is preferably 1 to 15% by weight, and more preferably 3 to 12% by weight.

  In the present invention, it is preferable that a pigment or a colored resin is dispersed in the ink as the colorant. Thereby, in the surface layer of the recording medium, the colorant in the ink and components other than the colorant are easily separated. For this reason, the colorant tends to stay on the surface layer of the recording medium, and the image quality can be improved. Furthermore, it is less susceptible to the characteristics of the recording medium than when the dye is dissolved in the ink, and the colorant tends to stay on the surface layer of the recording medium. Therefore, the number of recording media in which the visibility of dots due to pretreatment decreases increases, and according to the recording media, pretreatment with a treatment liquid reduces the visibility of dots due to preliminary ejection, thereby improving image quality. Can be improved.

  Hereinafter, the water-based ink will be described. The water-dispersible colorant is not particularly limited, but is a pigment in which one or more hydrophilic groups are bonded to the surface of the pigment directly or through other atomic groups, a resin emulsion colored with the pigment, a surface active property. Examples thereof include pigments dispersed and stabilized by an agent and / or a water-soluble polymer having an average molecular weight of 50,000 or less, and two or more of them may be used in combination.

  Such a colorant has excellent water resistance, light resistance, and gas resistance because the pigment is in an aggregated state (including a crystalline state) or coexists with a resin, and improves image storage stability. Can do. In particular, when using a pigment in which one or more hydrophilic groups are bonded to the surface of the pigment directly or through another atomic group, or a resin emulsion colored with a pigment, Since the viscosity can be lowered, the amount of resin or wetting agent added can be increased.

  It does not specifically limit as a pigment, An organic pigment and an inorganic pigment can be used, You may use 2 or more types together. Of these, organic pigments are preferred from the standpoint of specific gravity.

  The organic pigment is not particularly limited, but azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, Examples thereof include carbon black.

  Examples of the inorganic pigment include, but are not limited to, iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.

  Moreover, it is preferable that the average particle diameter of the pigment in an aqueous ink is 0.01-0.30 micrometer. When the average particle size is less than 0.01 μm, light resistance and feathering may be deteriorated, and when it exceeds 0.30 μm, clogging may occur in a nozzle or a filter in an ink jet apparatus.

  Although resin is not specifically limited, From the miscibility with a pigment, it is preferable that pH is 6-11, and 7-9 are still more preferable.

  The average particle size of the resin in the water-based ink is preferably 50 nm or more. If the average particle size is less than 50 nm, the viscosity may increase. Furthermore, the average particle diameter of the resin in the aqueous ink is preferably 500 nm or less, and more preferably 150 nm or less. When the average particle diameter exceeds 500 nm, the dischargeability of the water-based ink may be lowered.

  The resin preferably has an action of fixing the pigment to the paper, and in order to improve the fixability, the minimum film-forming temperature (MFT) is preferably 20 ° C. or lower. On the other hand, the resin preferably has a glass transition point of −30 ° C. or higher. When the glass transition point is less than -30 ° C, the resin film becomes more viscous and the printed matter may be tacked.

  In addition to the colorant, the water-based ink may further contain additives such as a wetting agent, a penetrating agent, an antiseptic / antifungal agent, an antirust agent, an antioxidant, and a pH adjusting agent.

  When a wetting agent is added to the water-based ink, clogging of the nozzles of the head due to drying can be suppressed. The wetting agent is not particularly limited, but ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, 1,3-propanediol, 2-methyl-1,3 -Propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, 3 -Polyhydric alcohols such as methyl-1,3-butanediol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, Alkyl ethers of polyhydric alcohols such as ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, etc. Aromatic ether amount of polyhydric alcohol; nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; formamide Amides such as N-methylformamide, formamide, N, N-dimethylformamide; monoethanolamine, diethanolamine, triethanol Amines such as ruamine, monoethylamine, diethylamine and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol; and aqueous solvents such as propylene carbonate, ethylene carbonate and γ-butyrolactone. Also good. The wetting agent is used by mixing with water.

  Further, when a penetrant is added to the water-based ink, the surface tension can be reduced and the wettability of the water-based ink to the recording medium can be improved, and as a result, the penetration speed of the water-based ink into the recording medium can be improved. Can do. The water-based ink preferably has a surface tension of 20 to 60 mN / m, and more preferably 30 to 50 mN / m from the viewpoint of achieving both wettability to the recording medium and droplet formation.

  Examples of penetrants include polyoxyethylene alkylphenyl ether surfactants, acetylene glycol surfactants, fluorine surfactants, silicon surfactants, polyoxyethylene alkyl ether surfactants, polyoxyethylene polyoxy Examples include propylene alkyl ether surfactants.

  Furthermore, when an antiseptic / antifungal agent is added to the water-based ink, the growth of bacteria can be suppressed, and the storage stability and the image quality stability can be improved.

  Further, when a rust inhibitor is added to the water-based ink, a coating can be formed on the metal that the water-based ink such as the head contacts, thereby suppressing corrosion.

  Furthermore, when an antioxidant is added to the water-based ink, even when a radical species that causes corrosion is generated in the metal in contact with the water-based ink, the corrosion can be suppressed by eliminating the radical species.

  Further, the pH of the ink can be adjusted by adding a pH adjuster to the water-based ink. The water-based ink preferably has a pH of 3 to 11, and more preferably 6 to 10 from the viewpoint of suppressing corrosion of the metal with which the water-based ink comes into contact.

  Furthermore, the water-based ink preferably has a viscosity of 1.0 to 20.0 mPa · sec, and more preferably 2.0 to 10.0 mPa · sec, from the viewpoint of ejection stability.

  When an image is formed using water-based ink, for example, fixing can be promoted by heating the recording medium and the ink to 50 to 200 ° C. before or after printing.

  Ink is usually used in a container. The container is not particularly limited, and the shape, structure, size, material, and the like can be appropriately selected according to the purpose. For example, a container having a bag formed of an aluminum laminate film, a resin film, or the like Is mentioned.

  FIG. 13 shows a cartridge as an example of a container for containing ink. After the cartridge 240 is filled with ink from the injection port 242 and exhausted, the injection port 242 is fused and closed. At this time, the bag 241 is made of a packaging material such as a non-permeable aluminum laminate film, and is usually accommodated in a plastic cartridge case 244. Such a cartridge 240 is configured to be detachably attached to the ink jet apparatus. When the cartridge 240 is attached to the ink jet apparatus, a needle attached to one end of a tube that supplies ink to the sub tank is pierced and used by a discharge portion 243 made of a rubber member.

  In the present invention, the treatment liquid is colorless or light-colored because an image is formed using ink after pretreatment, but it may be either aqueous or oily. Further, when ink is ejected onto the pretreated recording medium, the components in the processing liquid come into contact with the components in the ink, thereby causing a chemical reaction or interaction. Specifically, such a chemical reaction or interaction causes the colorant in the ink to be insolubilized or aggregated, or to cause changes in physical properties such as ink viscosity or permeability.

  Although it does not specifically limit what causes insolubility and aggregation by an ion exchange reaction with respect to the anionic dye and pigment used as a coloring agent, A polyvalent metal salt, a cationic resin, a cationic particle, an organic acid, etc. 2 or more may be used in combination. These contain counter ions whose solubility in the vehicle is inferior to that of dyes and pigments, and the ion exchange reaction reduces the solubility and dispersion stability of the colorant, which can lower the fluidity. it can. For this reason, according to the recording medium, pretreatment with the treatment liquid can reduce dot visibility by preliminary ejection and improve image quality.

  The polyvalent metal salt is not particularly limited, and aluminum chloride, calcium chloride, aluminum nitrate, magnesium nitrate, magnesium chloride, calcium nitrate, magnesium hydroxide, aluminum sulfate, ammonium alum and the like can be used, and more specifically. Is magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, calcium nitrate tetrahydrate, calcium acetate monohydrate, calcium chloride anhydrous, calcium lactate pentahydrate, calcium formate -Anhydride, magnesium benzoate trihydrate, magnesium sulfate heptahydrate and the like may be mentioned, and two or more may be used in combination.

  Although it does not specifically limit as a cationic resin, A trialkylammonium salt, a dimethylamine / epichlorohydrin polycondensate, a dimethylamine / ammonia / epichlorohydrin condensate, poly (dialkylaminoalkyl methacrylate quaternized salt) ), Diallylamine hydrochloride / acrylamide copolymer, poly (diallylamine hydrochloride / sulfur dioxide), polyallylamine and its salts, poly (allylamine hydrochloride / diallylamine hydrochloride), acrylamide / diallylamine copolymer, polyvinylamine copolymer , Dicyandiamide / formalin polycondensate, dicyandiamide / ammonium chloride / urea / formaldehyde condensate, polyalkylene polyamine / dicyandiamide ammonium salt condensate, polydiallylmethylamine hydrochloride, poly (di Rildimethylammonium chloride), poly (diallyldimethylammonium chloride / sulfur dioxide), poly (diallylamine salt / sulfur dioxide), poly (diallyldimethylammonium chloride / diallylamine salt derivative), acrylamide / diallyldimethylammonium chloride copolymer, acrylic acid Salt / acrylamide / diallylamine hydrochloride copolymer, polyethyleneimine, ethyleneimine derivatives such as acrylamine polymer, polyethyleneimine alkylene oxide modified products, cationic modified products of nonionic polymers such as acrylamide and PVA, etc. You may use together.

  Cationic particles include cationic resin emulsions and cationic white or light color pigments. Examples of the cationic resin emulsion include styrene-acrylic cations such as Acryt UW319-SX, Acryt RKW-460, Acryt RKW-400SX, Acryt RKW-450SX, Acryt RKW-450 (manufactured by Taisei Kako). Can be used. As the cationic white or light pigment, cationic silica such as Snowtex AK (manufactured by Nissan Chemical Industries), SMR8-17-109SMSG 3CS (manufactured by Grace Japan), CEP10AK97002 (manufactured by CABOT) is used. A silica sol or the like in which spherical silica having a particle size of around 0.1 μm is dispersed in water is preferable.

  The organic acid is not particularly limited, but acetic acid, succinic acid, lactic acid, salicylic acid, benzoic acid, glucuronic acid, ascorbic acid, arginic acid, cysteine, oxalic acid, fumaric acid, maleic acid, malonic acid, lysine, malic acid, citric acid. Acid, glycine, glutamic acid, succinic acid, tartaric acid, phthalic acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds or A salt etc. are mentioned, You may use 2 or more types together. Moreover, when using an organic acid, you may use a Buffer agent together.

  Moreover, it is preferable that a process liquid contains surfactant. Thereby, the wettability of the processing liquid to the recording medium can be improved, and the miscibility between the processing liquid and the ink can be improved. Furthermore, the permeability of components other than the colorant in the ink to the recording medium can be improved. For this reason, the processing liquid acts efficiently on the ink, and the amount of the processing liquid used can be reduced.

  The surfactant is not particularly limited as long as it does not react and insolubilize with the components constituting the treatment liquid from the viewpoint of the stability and coating properties of the treatment liquid. When the treatment liquid contains a polyvalent metal salt, a cationic resin, and cationic particles, as the surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant can be used. , Polyoxyethylene alkylphenyl ether surfactants, acetylene glycol surfactants, nonionic fluorine surfactants, nonionic silicone surfactants, alkylbetaine amphoteric surfactants, polyoxyethylene alkyl ether surfactants Surfactant, polyoxyethylene polyoxypropylene alkyl ether surfactant and the like can be mentioned.

  As the treatment liquid, there are those in which the components in the treatment liquid are phase-separated from the components in the ink, and those in which the resin in the treatment liquid forms a complex salt with the resin in the ink to cause changes in physical properties such as viscosity changes. Can be used. Examples of such a resin combination include poly (dimethylacrylamide) and acrylic acid.

  Further, the same additive as that of the ink can be added to the treatment liquid.

  The physical properties of the treatment liquid depend on the application process of the treatment liquid and cannot be specified in general. However, in the case of ink-jet application, the viscosity is 1.0 to 20.0 mPa · sec as in the case of ink. Is preferable, and 2.0 to 10.0 mPa · sec is more preferable.

  Further, the treatment liquid is used in a container, like the ink.

  Hereinafter, although an example is shown, the present invention is not limited to these. In addition, a part means a weight part.

<Preparation of treatment liquid for inkjet coating>
Cationic silica ST-AK (manufactured by Nissan Chemical Co., Ltd.) 15 parts (solid content), glycerin 10 parts, nonionic surfactant Softanol EP-7025 (manufactured by Nippon Shokubai Co., Ltd.), 2-ethyl-1,3- 2 parts of hexanediol, 4 parts of cationic surfactant cation G50 (manufactured by Sanyo Chemical Co., Ltd.), 0.2 part of sodium dehydroacetate, 0.2 part of sodium thiosulfate and 67.6 parts of ion-exchanged water were mixed. Stir for hours. Next, pressure filtration was performed using a 0.8 μ cellulose acetate membrane filter to remove coarse particles and the like, and a treatment liquid for inkjet coating was obtained.

<Preparation of treatment liquid for roller application>
32 parts by weight of a cationic resin (poly (dimethyldiallylammonium chloride)) Unisense CP103 (manufactured by Senka), 3 parts of a cationic surfactant, cation G50 (manufactured by Sanyo Chemical Co., Ltd.), and a nonionic surfactant, Softanol EP-7025 1 part (manufactured by Nippon Shokubai Co., Ltd.), 15 parts of ethylene glycol, 15 parts of glycerin, 15 parts of 1,5-pentanediol and 18 parts of ion-exchanged water were mixed and stirred for 1 hour. Next, pressure filtration was performed using a 5 μ stainless sintered filter to remove coarse particles and the like, and a treatment liquid for roller coating was obtained.

<Preparation of cyan ink>
1,5-pentanediol 22.5 parts, glycerin 7.5 parts, 2-pyrrolidone 2 parts, 2-ethyl-1,3-hexanediol 2 parts, nonionic surfactant Softanol EP-7025 (Nippon Shokubai Co., Ltd.) 1 part), 0.2 part of Proxel LV (manufactured by Avecia) and 44.8 parts of ion-exchanged water were mixed and stirred for 1 hour. Next, 20 parts of pigment CAB-O-JET300 (manufactured by Cabot) was added and stirred for 1 hour. Furthermore, using a 0.8 μ cellulose acetate membrane filter, the mixture was filtered under pressure to remove coarse particles and the like to obtain a cyan ink.

<Paper>
My paper (manufactured by NBS Ricoh) as PPC paper, high grade plain paper type E (manufactured by Ricoh) as plain paper for ink jet, super fine paper (manufactured by Epson) as a special coated paper for ink jet, general printing As the coated paper, an OK top coat + (manufactured by Oji Paper Co., Ltd.) was used.

Example 1
Change the control software of the inkjet printer IPSIO G707 (manufactured by Ricoh) and modify it so that it does not perform the normal pre-ejection operation. Also, the head maintenance unit can be detached and the maintenance unit can be replaced according to the ink did.

  The cleaning liquid was passed through the ink supply path of the black ink and the ink flow path in the head for cleaning. After sufficiently replacing the ink, the cleaning liquid was replaced by passing pure water. Next, pure water was passed through the ink supply path and the ink flow path in the head and dried. In addition, as a washing | cleaning liquid, the aqueous solution containing 5 weight% of nonionic surfactant Softanol EP-7025 (made by Nippon Shokubai Co., Ltd.) was used.

  Next, the treatment liquid for inkjet application was filled in the cartridge (see FIG. 13), and the treatment liquid was filled in the ink supply path and the ink flow path in the head. The maintenance of the head filled with the treatment liquid was performed by exchanging with a dedicated maintenance unit.

  Using such an apparatus, printing was performed by discharging cyan ink, and the evaluation described later was performed.

(Example 2)
Evaluation was carried out in the same manner as in Example 1 except that the ink jet apparatus shown in FIG. 1 was used and a treatment liquid for roller coating was used.

(Evaluation methods)
<Density of image where dots do not overlap>
For an image in which dots formed at equal intervals with a 75 dpi pitch do not overlap (see FIG. 10), the density α of the preprocessed image and the density β of the unprocessed image are expressed as a density measuring device X-Rite 938. The case where α-β is 0.1 or more is A, the case where it is −0.1 or more and less than 0.1 is B, and the case where it is less than −0.1 is C. The evaluation results are shown in Table 1.

＜予備吐出パターンの官能評価＞
ドット間の間隔が１０ドット以上であり、周期性を持たないパターンを、予備吐出される領域に前処理されている用紙及び前処理されていない用紙にインクを予備吐出することにより印刷し、予備吐出パターンの目立ち具合を、Ｄ６５光源下で印刷面から５０ｃｍ離れて評価し、気にならない場合を○、目に付くが、汚いとは感じない場合を△、汚いと感じる場合を×として判定した。評価結果を表２に示す。

<Sensory evaluation of preliminary discharge pattern>
A pattern having an interval between dots of 10 dots or more and having no periodicity is printed by preliminarily ejecting ink onto a pre-processed paper and a non-pre-processed paper in a pre-discharged area. The degree of conspicuousness of the discharge pattern was evaluated at a distance of 50 cm from the printing surface under a D65 light source. A case where it was not noticed was judged as ◯, a case where it was noticeable but not felt as dirty, and a case where it felt dirty was judged as ×. . The evaluation results are shown in Table 2.

（評価結果）
前処理される場合の方が前処理されない場合よりも、ドットが重ならない画像の濃度が高いマイペーパーは、前処理することにより予備吐出パターンが目立ちやすくなっている。

(Evaluation results)
In the case of pre-processing, the pre-discharge pattern is more conspicuous by pre-processing my paper having a higher image density where dots do not overlap than when pre-processing is not performed.

  Further, there is no difference in the conspicuousness of the preliminary discharge pattern depending on the presence or absence of the preprocessing on the super fine dedicated paper in which the change in the density of the image where the dots do not overlap is small when the preprocessing is performed and when the preprocessing is not performed.

  On the other hand, in the case of pre-processing, the pre-discharge pattern is less noticeable by pre-processing high-grade plain paper or OK top coat +, which has a lower image density where the dots do not overlap, than when the pre-processing is not performed. Yes.

  From the above, it is possible to reduce the conspicuousness of the preliminary ejection pattern by evaluating the density of an image in which dots do not overlap due to the presence or absence of preprocessing and performing preprocessing based on the difference in image density.

It is a side view which shows an example of the inkjet apparatus of this invention. It is a top view which shows the head unit of FIG. FIG. 3 is a partially enlarged view of the head unit of FIG. 2. It is a side view which shows the other example of the inkjet apparatus of this invention. It is a top view which shows the inkjet apparatus of FIG. It is a block diagram which shows the control part of the inkjet apparatus of FIG. 3 is a flowchart illustrating an example of a printing process performed by the ink jet apparatus of FIG. 1. It is a figure which shows a paper and its printing area. 6 is a flowchart illustrating another example of a printing process performed by the ink jet apparatus of FIG. 1. It is a figure which shows an example of the image which can compare the presence or absence of pre-processing. It is a figure which shows the other example of the image which can compare the presence or absence of pre-processing. It is a figure which shows the other example of the image which can compare the presence or absence of pre-processing. It is a side view which shows an example of the container which accommodates ink.

Explanation of symbols

101, 102 Inkjet device 107 Cartridge 108 Sub tank 110 Head unit 114 Paper 131 Carriage 134 Movable blade 135 Treatment liquid 136, 137, 138 Roller 139 Counter roller 140 Cartridge

Claims (6)

An inkjet apparatus comprising: an ejection unit that ejects ink onto a recording medium; and a pretreatment unit that pretreats the recording medium with a colorless or light-colored processing liquid before the ink is ejected onto the recording medium. And
The ejection means can preliminarily eject the ink onto the recording medium,
The ink jet apparatus according to claim 1, wherein the pretreatment means is capable of pretreating a predischarge region of the recording medium with the treatment liquid. The ejection means can eject the ink onto the recording medium to form an image in which dots do not overlap,
2. The preprocessing means can preprocess an area including a part of an area where an image in which dots of the recording medium do not overlap are formed with the processing liquid. Inkjet device.   The inkjet apparatus according to claim 1, wherein the treatment liquid includes a surfactant and at least one of a polyvalent metal salt, a cationic resin, cationic particles, and an organic acid.   The inkjet apparatus according to claim 1, wherein a pigment or a colored resin is dispersed in the ink. A preliminary ejection method for performing preliminary ejection using the inkjet device according to any one of claims 1 to 4,
The pretreatment means pretreating the predischarge region of the recording medium with the treatment liquid;
A preliminary discharge method comprising: a step of preliminary discharging the ink to a preprocessed area of the recording medium.   In the case where the density of an image formed by pre-ejecting the ink onto the recording medium under the same conditions is lower in the case where the pre-processing is performed than in the case where the pre-processing is not performed, the pre-processing means 6. The preliminary ejection method according to claim 5, wherein the preliminary ejection area of the recording medium is pretreated with the processing liquid.

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