JP2005271400A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which positively absorbs only a surplus of ink deposited on a recording medium, eliminates ink offset, and curling and cockling of the recording medium and improves ink drying performance, thereby achieving good printing of image on the recording medium. <P>SOLUTION: In the inkjet recording device, recording heads 28T to 28Y function to record an image by landing printing liquid (inks of respective colors, and a process liquid for inducing aggregation in a pigment of each ink) on a sheet. Herein a liquid absorbing device 34 for absorbing a surplus of the ink successively impacting the sheet by the recording heads 28T to 28Y, is arranged on a downstream side of the recording head 28T to 28Y, and a surface of the liquid absorbing device 34, that makes a contact with the surplus liquid of the print liquid is made hydrophilic. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method for performing recording by discharging a printing liquid (ink, treatment liquid) from a recording head to a recording medium.

  In recent years, the spread of color documents in offices is remarkable, and various output devices have been proposed. In particular, a small-sized and low-cost inkjet method is used in various output devices.

  A recording head used in an ink jet system includes an energy generation unit, an energy conversion unit that converts energy generated by the energy generation unit into an ink discharge force, an ink discharge port that discharges an ink droplet by the ink discharge force, and an ink discharge port And an ink supply path for supplying ink. As the energy generating means, means that heats ink by means using an electromechanical transducer such as a piezo element or an electrothermal transducer having a heating resistor generates air bubbles, and ejects ink droplets by generating the bubbles. Etc.

  In such an ink jet method, since the ink is mainly composed of a liquid component, if the ink droplets remain on the recording medium after landing on the recording medium, the ink is transferred to another recording medium. This becomes more noticeable by high-speed printing. In addition, when a system having a processing liquid in addition to the ink is used to achieve high image quality, the amount of liquid increases, so that compared to the case without the processing liquid, a large amount of liquid is absorbed in the recording medium, resulting in curling and cockle. There's a problem. Also, when printing on the back side, head rubbing or the like occurs, causing image quality degradation.

  For this reason, in order to quickly dry the ink after landing on the recording medium, it has been proposed to carry out heating and ventilation. However, there are concerns about a large amount of power consumption and an increase in the size of the apparatus. On the other hand, there is a method of absorbing excess ink remaining on the recording medium with blotting paper, but this is not practical because it may also absorb the ink colorant component.

Therefore, in Japanese Patent Laid-Open No. 2001-179959, for the purpose of absorbing only the liquid component (liquid solvent) of the ink, after printing (after the ink has landed on the recording medium), the colorant (coloring material) and the release are released. It is disclosed that only an excess liquid (liquid solvent) of ink remaining on a recording medium is absorbed by a liquid absorber covered with a member having a property.
JP 2001-179959 A

  However, in the above proposal, since the absorber is made of a material having releasability with respect to the colorant on the contact surface (surface) with the liquid solvent, the absorber is also released from the liquid solvent, so that the absorption is successful. Can not. Furthermore, since a hydrophobic portion is present on the surface, the ink is eliminated and the image quality is deteriorated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reliably absorb only the excess ink that has landed on a recording medium, improve ink back-off, curl, cockle, and drying properties, and obtain an excellent image. It is to provide a recording apparatus and an ink jet recording method.

The above problem is solved by the following means. That is,
The inkjet recording apparatus of the present invention is
A recording head for landing an ink containing a pigment on a recording medium;
Means for coarsely agglomerating the pigment to 0.5 μm or more substantially simultaneously with the landing of the ink after landing the ink on the recording medium;
Liquid absorbing means for absorbing excess ink remaining on the recording medium after the ink has landed on the recording medium; and
The liquid absorbing means is an absorber having a hydrophilic surface that comes into contact with the excess liquid.

  In the ink jet recording apparatus of the present invention, after the ink is landed on the recording medium, the pigment is coarsely aggregated. Then, excess ink remaining on the recording medium is absorbed by the liquid absorbing means. At this time, since the surface of the liquid absorbing means that comes into contact with the excess liquid is hydrophilic, the ink or the excess liquid is absorbed well without being released from the liquid absorbing means, and the ink is not repelled. In addition, since the pigment of the ink is physically or chemically aggregated to be enlarged, the liquid absorbing means can effectively absorb only the excess liquid of the ink and improve the image density. For this reason, it is possible to reliably absorb only the excess liquid of the ink that has landed on the recording medium, improve the ink back-off, curl, cockle, and drying, and obtain a good image.

  Here, the indicator that the surface is hydrophilic indicates an object whose contact angle is 35 ° or less when, for example, an aqueous solution having a surface tension of 40 mN / m is dropped on the constituent material. This means that ink whose surface tension is adjusted to 20 to 45 mN / m wets well.

  Moreover, the hydrophilic surface prescribed | regulated here shows that it comprises with a material with good wettability of water, You may comprise a part of surface of hydrophobic material hydrophilizing. That is, the hydrophilic surface constituent material (hydrophilic material) may be a material modified to be hydrophilic by surface treatment. For example, a material obtained by partially hydrophilizing a hydrophobic material is used in the present invention. be able to. Specifically, the surface of a PTFE resin film in which minute holes are formed to allow liquid to pass through may be made hydrophilic by plasma treatment or the like.

  In the ink jet recording apparatus of the present invention, it is preferable that the size of the pigment before aggregation is 10 to 200 nm.

On the other hand, the inkjet recording method of the present invention comprises:
A step of landing an ink containing a pigment on a recording medium by a recording head;
A step of landing the ink on the recording medium and coarsely aggregating the pigment to 0.5 μm or more;
A step of absorbing the excess liquid by a liquid absorbing means for absorbing the excess liquid of the ink remaining on the recording medium;
Have
The liquid absorbing means is an absorber having a hydrophilic surface that comes into contact with the excess liquid.

  In the ink jet recording method of the present invention, as in the ink jet recording apparatus of the present invention described above, only the excess liquid of the ink that has landed on the recording medium is surely absorbed, and ink set-off, curling, curl, and drying are improved. And a good image can be obtained.

  According to the ink jet recording apparatus and the ink jet recording method of the present invention, it is possible to reliably absorb only the excess liquid of the ink that has landed on the recording medium, and the ink is transferred to another recording medium due to poor drying, curling, cockle, And the drying property can be improved. Further, since the pigment is aggregated, a recorded matter having a high image density can be obtained. In addition, when the surface of the liquid absorbing means is hydrophobic, the ink (surplus liquid) itself also repels, so that when different color inks are present at close positions, there is a problem that the image quality deteriorates due to color mixing. However, in the present invention, the color mixture of the excess liquid is prevented and the image quality is improved.

  Hereinafter, an ink jet recording apparatus of the present invention will be described in detail with reference to the drawings. An ink jet recording method will be described together with the ink jet recording apparatus of the present invention. In addition, the same code | symbol is provided and demonstrated to the member which has the substantially same function through all the drawings. Further, in all drawings, P indicates a sheet (recording medium).

[Embodiment]
FIG. 1 is a schematic configuration diagram showing an ink jet recording apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the inkjet recording apparatus 10 uses a sheet supply unit 12 that feeds out a sheet, a registration adjustment unit 14 that controls the attitude of the sheet, and a sheet (recording medium) using a printing liquid (ink, processing liquid). ) Basically includes a recording unit 16 that forms an image and a paper discharge unit 18 that discharges the paper on which the image has been formed by the recording unit 16.

  The sheet supply unit 12 includes a stocker 20 in which sheets are stacked and stocked, and a transport device 22 that transports the sheets one by one from the stocker 20 to the registration adjusting unit 14.

  The registration adjusting unit 14 includes a loop forming unit 24 and a guide member 26 that controls the posture of the paper. By passing through this portion, the skew is corrected using the stiffness of the paper and the conveyance timing is controlled. Thus, the recording unit 16 is entered.

  The recording unit 16 includes a recording head 28 that forms an image by causing a printing liquid (ink, processing liquid) to land on the paper (recording medium) with respect to the paper, and a maintenance device that is disposed to face the nozzle surface of the recording head 28. 30 and a transport unit 32 that transports a sheet between the recording head 28 and the maintenance device 30. The recording head 28 is arranged so that the processing liquid (T), black (K), cyan (C), magenta (M), yellow (Y) (in order of ink → processing liquid may be used) (The order of ink is more preferable), so that full-color printing is possible. If necessary, the reference numbers of the corresponding recording heads are given T, K, C, M, and Y codes. (As 28T, 28K, 28C, 28M, 28Y). Hereinafter, the same applies to other members (maintenance devices 30T to 30Y).

  In the vicinity of the outlet of the recording unit 16, that is, on the downstream side of the recording head 28Y, a liquid absorbing device 34 that absorbs excess liquid of the printing liquid (ink, processing liquid) landed on the paper by the recording heads 28K to 28T. Is provided. By this liquid absorbing device 34, ink (including processing liquid) is sequentially landed on the paper by each of the recording heads 28 </ b> T to 28 </ b> Y, and then the excess ink on the paper is absorbed.

  Each recording head 28 and maintenance device 30 are unitized, and the recording head 28 is configured to be separable across the maintenance device 30 and the sheet conveyance path. Therefore, in the case of paper jam, the jammed paper can be easily taken out.

  The paper discharge unit 18 stores the paper on which the image is formed by the recording unit 16 in the tray 38 via the paper discharge belt 36.

  As the printing liquid, a two-component ink set is used which includes an ink containing at least a pigment, a water-soluble solvent, and water, and a treatment liquid having an action of aggregating the pigment of the ink. . In the present embodiment, as described above, the processing liquid is ejected by the recording head 28T, and full color inks of black ink, cyan ink, magenta ink, and yellow ink are ejected by the recording heads 28K to 28Y. Details will be described later.

  Next, the liquid absorbing device 34 will be described.

  As the liquid absorbing device, a roller method, a belt method, a winding paper method, or the like can be adopted. By employing these methods, it is possible to efficiently absorb the excess liquid of the printing liquid with a simple configuration.

  Hereinafter, a specific configuration will be described. As the liquid absorption device 34, for example, as shown in FIG. 2, a roll type constituted by a liquid absorption roll in which an outer peripheral surface of a metal shaft 50 is sequentially coated with an absorber layer 52 and a hydrophilic absorption layer 54. A liquid absorbing device 34 may be mentioned.

  The hydrophilic absorption layer 54 is a member that constitutes a surface in contact with the surplus liquid of the printing liquid, and is made of a hydrophilic material. As this hydrophilic material, it is preferable to use a material having a contact angle of 35 ° or less when an aqueous solution of 99% pure water and Surfinol 465: 1% manufactured by Nissin Chemical Co. is dropped. Specifically, cellulose, starch, gelatin, acrylic fiber hydrolysis system, cross-linked polyacrylate system, hydrophilic treatment polyester, hydrophilic treatment olefin, hydrophilic treatment rayon, PVA fiber, hydrophilic treatment polyvinylidene fluoride, etc. It is done.

  The hydrophilic absorbing layer 54 agglomerates the pigment using a two-component ink set, and then comes into contact with the excess ink. The surplus liquid is absorbed by the absorber layer 52 through the hydrophilic absorption layer 54. For this reason, the hydrophilic absorption layer 54 substantially passes only the excess liquid without passing through the pigment aggregate. Here, the aggregate is generated by ink in an ink set to be described later and a treatment liquid that exerts an aggregating action on the ink.

  Specifically, when the hydrophilic absorbent layer 54 alone filters fine particles having an average particle diameter of 5 μm, the recovery rate thereof is preferably 90% or more. That is, when the recovery rate of fine particles having an average particle diameter of 5 μm is 90% or more, it means that the hydrophilic absorption layer 54 substantially passes only the excess liquid without passing through the pigment aggregate. The recovery rate is obtained as follows. The number of particles of 5 μm or more before and after the filtration was measured with Accusizer TM770 Optical Particles Sizer (manufactured by Particle Sizing System). The measurement was carried out according to a predetermined measuring method by putting 2 μl of an aqueous inkjet recording liquid in a measuring cell, and converted into a desired unit. Recovery rate = (number of particles of 5 μm or more measured before filtration−number of particles of 5 μm or more measured of the filtrate) / number of particles of 5 μm or more measured before filtration.

  The hydrophilic absorption layer 54 having such a configuration is preferably provided with a plurality of holes. And the hole diameter (maximum diameter) has preferable 0.01-100 micrometers, More preferably, it is 0.1-20 micrometers, More preferably, it is 5-10 micrometers. Furthermore, the thickness is preferably 0.01 to 10 mm, more preferably 0.1 to 1.5 mm. The thickness of the layer is preferably 5 times or more with respect to the average pore diameter. If this hole exceeds the above range, not only the excess liquid but also the pigment may not be separated together and may be absorbed by the absorber layer 52, and if it is less than the above range, the amount of excess liquid passing through decreases. In some cases, the absorber layer 52 may not be efficiently absorbed.

  Moreover, it is preferable that it is 10 to 70% with respect to the hydrophilic absorption layer 54 surface, and, as for the area ratio of a hole, 15 to 50% is more preferable. By setting the area ratio of the holes in the above range, the surplus liquid passes through the holes of the hydrophilic absorption layer 54 more efficiently, and the surplus liquid can be absorbed well by the absorber layer 52.

  Further, the hydrophilic absorption layer 54 may be made of a material obtained by hydrophilizing the surface of a hydrophobic material (for example, PTFE resin film) in which minute holes are formed so as to transmit a liquid by plasma treatment or the like.

  The absorber layer 52 absorbs the excess liquid that has contacted the hydrophilic absorption layer 54 via the hydrophilic absorption layer 54, and from the viewpoint of efficiently absorbing the excess liquid, the porous body or the fiber body is Good. Specific examples of the constituent material include natural fiber bodies, chemical fiber bodies, and porous bodies such as wool, cotton, silk, polyester, polyamide, polyacrylonitrile, polypropylene, cellulose, urethane, and melamine. Further, an organic or inorganic filler may be added to these materials in order to control the strength and the surface state.

  The absorbent layer 52 preferably has a structure in which the fiber density or the pore density is increased from the outside to the inside. Thereby, the excess liquid absorbed through the hydrophilic absorption layer 54 can be moved to the inside (the metal shaft 50 side) by capillary action.

  The metal shaft 50 is comprised with metal materials, such as stainless steel and aluminum, for example. Further, as shown in FIG. 3, a spiral groove 50 a is provided on the outer peripheral surface of the metal shaft 50.

  In the roll-type liquid absorber of this embodiment, the surface of the hydrophilic absorbent layer 54 is brought into contact with the excess liquid of the printing liquid remaining on the paper while rotating the liquid absorbent roll, and the hydrophilic absorbent layer 54 is interposed therebetween. Excess liquid is absorbed by the absorber layer 52. Then, the surplus liquid absorbed in the liquid absorber layer 52 reaches the groove 50a of the metal shaft 50, and when the metal shaft 50 rotates, the surplus liquid moves to one end through the groove 50a, and a recovery container (not shown) Is recovered. In this way, the excess liquid of the printing liquid on the paper (recording medium) is absorbed.

  As another form of the liquid absorbing device 34, as shown in FIG. 4, a metal shaft 50, a stretching shaft 56, a liquid absorbing endless belt 58 stretched on both shafts, and a liquid absorbing endless And an endless belt type liquid absorbing device 34 constituted by a blade 60 for cleaning the belt surface.

  The layer structure of the liquid absorption endless belt 58 is a structure in which an absorber layer 52 and a hydrophilic absorption layer 54 are laminated from the inner peripheral surface side, and these can be configured in the same manner as the above-described roll system. A spiral groove 50 a is provided on the outer peripheral surface of the shaft 50. Although not shown, a similar spiral groove is provided on the outer peripheral surface of the stretching shaft 56.

  In the endless belt type liquid absorbing device 34 of the present embodiment, the endless belt 58 is rotated along with the rotation of the metal shaft 50 or the stretching shaft 56, and similarly to the roll type liquid absorbing device 34, the paper is on the sheet (recording medium). Absorbs excess liquid of printing liquid.

  Further, as another form of the liquid absorbing device 34, as shown in FIG. 5, a winding paper 62 for absorbing liquid, a roll 64 around which the winding paper 62 is wound, and a winding wound around the roll 64 There is a winding paper type liquid absorbing device constituted by a winding roll 66 for winding the paper 62 from one end and a pressing roll 68 for pressing the winding paper against the paper from the winding surface side.

  The layer configuration of the liquid absorbent web 62 is a configuration in which a liquid permeation preventing layer 70, a liquid holding layer 72, an absorber layer 52, and a hydrophilic absorbent layer 54 are laminated from the winding surface side of the roll 64. It can be set as the structure similar to the said roll system. However, in the above roll method, the excess liquid recovery mechanism is provided by the spiral groove 50a provided in the metal shaft 50, whereas in this embodiment, it is not provided, so that higher liquid holding ability is enhanced. For this purpose, the liquid holding layer 72 is provided so as to be sandwiched between the liquid permeation preventing layer 70 and the liquid absorber layer 52.

  As a constituent material of the liquid holding layer 72, for example, a powdery hydrophilic polymer is preferably exemplified. Examples of the water-soluble polymer include starch-based, cellulose-based, synthetic polymer-based and the like. Specifically, for example, crosslinked polyacrylate-based, isobutylene / maleic acid-based, starch / polyacrylate-based, PVA / Examples include polyacrylates.

  As a constituent material of the liquid permeation preventive layer 70, any material may be used as long as the excess liquid retained by the liquid retaining layer 72 prevents leakage to the roll winding surface side. Examples thereof include polyethylene, polyethylene terephthalate, polypropylene, polyvinyl chloride, and polyvinylidene fluoride.

  In the winding paper type liquid absorbing device of this embodiment, the surface of the hydrophilic absorbing layer 54 is transferred to the excess liquid of the printing liquid remaining on the paper by the pressing roll 68 while the liquid absorbing winding paper 62 is wound up by the winding roll 66. And the surplus liquid is absorbed by the absorbent layer 52 through the hydrophilic absorbent layer 54. Then, the excess liquid absorbed by the liquid absorber layer 52 reaches the liquid holding layer 72, and the excess liquid is held and collected by the liquid holding layer 72. It is also possible to absorb the excess liquid while winding the winding roll 66 and the wound winding paper 62 on the roll 64 again.

  It is preferable that the liquid absorbing device 34 having any one of the above configurations has an absorption region corresponding to the maximum paper width of the paper as in the recording head 28 described later. Moreover, it is not necessary to make each structural layer a separate member, and you may comprise integrally with the same material.

  Next, the recording head 28, the maintenance device 30, and the conveying unit 32 that are constituent members of the recording unit 16 will be described in order.

  The recording head 28 may be any one of a thermal ink jet method, a piezo ink jet method, a continuous flow ink jet method, an electrostatic suction ink jet method, and the like that transfers a printing liquid directly to a sheet without contact.

  Further, as shown in FIG. 6, the recording head 28 has a printing area corresponding to the maximum sheet width PW of the sheet, and can print on the entire width of the sheet without scanning the recording head 28. That is, the printing is completed only by passing the paper once under the recording head 28.

  When the print margin is set on the paper, the print area of the recording head 28 has a width corresponding to the print area obtained by subtracting the print margin from the maximum paper width PW (more than the print area).

  In general, the sheet is transported at a predetermined angle with respect to the transport direction (skew), and there is a request for borderless printing. Therefore, the print area of the recording head 28 is larger than the recording area. It is desirable to make it large.

  The recording head 28 may be composed of a monolithic long head (head chip) in which nozzles are formed in a line over the print region, but from a combination of short heads (head chip; hereinafter, unit recording head). It is preferable to configure. Unit recording heads (short heads) can be manufactured in large quantities, and it is much easier to increase the yield of individual short heads compared to monolithic long heads. Therefore, it is possible to construct the recording head 28 by combining unit recording heads at a lower cost.

  For example, a unit recording head in which nozzles are arranged in a row on the nozzle surface is attached to two common substrates with the nozzle rows aligned, and is shifted from each other so that printing is possible without interruption in the print area. The head 28 can be configured. In this case, it can be shared with an inexpensive device (recording head) produced in large quantities, and the recording head 28 capable of full-width printing at a low price can be configured.

  As the unit recording head, a commercially available or known serial recording type ink jet recording head may be used. Further, the unit recording head may be configured by only the head chip, and the printing liquid may be supplied to the plurality of head chips through the printing liquid flow path (ink flow path) provided on the common substrate. Furthermore, it is preferable if each unit recording head can be replaced.

  Further, the recording head 28 may be configured by continuously arranging unit recording heads in which the nozzles in the unit recording head are formed to the end in the nozzle arrangement direction in the width direction. In order to adjust the nozzle pitch at the connecting portion between the unit recording heads, it is necessary to manufacture the end of the unit recording head with high accuracy. However, the recording head 28 can be miniaturized most.

  Furthermore, the nozzle array of the unit recording head may be linear, but is not limited to this. For example, it is possible to arrange the nozzles in a staggered manner.

  The maintenance device 30 disposed to face the recording head 28 includes a printing liquid receiving portion that stores at least the printing liquid (ink, processing liquid) discharged from the recording head 28 during non-printing. The printing (printing liquid discharge) performance is maintained constant. As described above, since the maintenance device 30 including the printing liquid receiving portion is disposed to face the recording head 28, the printing liquid transferred from the recording head 28 at the time of non-printing is reliably accommodated.

  The recording head 28 needs to discharge the printing liquid during non-printing (hereinafter referred to as a dummy jet) for the purpose of initializing the printing liquid discharge performance by drying the printing liquid (particularly water-based ink, solvent ink). There is.

  Even when the printing liquid (ink) is oily ink or solid ink that hardly dries, the influence of minute bubbles generated inside the recording head 28 during printing, the nozzle surface (printing liquid discharge surface) It is necessary to perform a dummy jet in order to remove and initialize the influence of the printing liquid and fine dust adhering to ().

  The maintenance device 30 (printing liquid receiving part) stores the printing liquid at the time of this dummy jet, and a printing liquid absorbing member may be arranged so that the stored printing liquid is not scattered. Or it is good also as a structure discharged | emitted to the drainage means provided in another place through the liquid penetration member for printing, a tube member, etc.

  The maintenance device 30 only needs to have at least the printing liquid receiving function, but may be configured to have other maintenance functions in order to maintain the discharge performance of the printing liquid. For example, a wiper member that cleans the nozzle surface may be provided, or a capping function that protects the nozzle surface by making it airtight may be used. Furthermore, it is good also as a structure which has a vacuum function which attracts | sucks the printing liquid etc. from a nozzle.

  It should be noted that functions other than the printing liquid receiving function, such as the wiping function and the capping function described above, do not necessarily have to be provided in the maintenance device 30, and a mechanism (wiping mechanism, capping mechanism, etc.) that performs the function is provided on the recording head side. It may be provided.

  The conveying means 32 conveys the paper by a method other than electrostatic adsorption (hereinafter referred to as a non-electrostatic adsorption method). That is, the conveying means 32 is not particularly limited as long as it can stably convey the sheet between the recording head 28 and the maintenance device 30 at a constant speed. For example, a combination of a conveyance roll, a conveyance belt, and a pressing means can be considered.

  Further, it is desirable that the transport unit 32 is disposed at a position different from the recording head 28 in the paper transport direction. This is because the maintenance device 30 can be easily disposed at a position facing the recording head 28.

  For example, it is conceivable that the transport unit 32 includes a transport roll 40 that abuts on the back surface of the paper and applies a driving force to the paper, and an urging unit (not shown) that presses the paper against the transport roll 40. .

  This is because, when the electrostatic adsorption method is adopted, the electrostatic adsorption state may not be stabilized depending on the thickness of the paper and the material of the paper, whereas the paper is pressed against the transport roll 40 by the urging means. This is because the driving force is reliably transmitted from the transport roll 40 to the sheet regardless of the thickness, material, and the like of the sheet, and the sheet can be stably conveyed.

  As the urging means, there are a method in which the urging member directly urges against the paper and a method in which the urging member does not directly contact the paper. As the latter method, for example, air blowing can be considered. It is excellent in that it does not touch the printed paper.

  On the other hand, in the present embodiment, as the former method, for example, a star wheel 42 to which a biasing force of a spring is applied via a shaft (not shown) is employed. That is, the paper is pressed against the transport roll 40 by the star wheel 42 elastically biased with respect to the transport roll 40 regardless of the thickness or material. As a result, the driving force is reliably transmitted from the transport roll 40, and the paper is stably transported.

  The shape of the star wheel 42 is not particularly limited as long as the contact area with the paper is minimized. The material of the star wheel 42 may be metal or plastic. For example, a SUS631H material obtained by curing SUS631H at a high temperature is suitable. The manufacturing method is not particularly limited, but etching, pressing, laser processing, and the like are possible.

  Therefore, even if the star wheel 42 comes into contact with the recording surface of the paper, the contact area with respect to the recording surface to which the printing liquid has just transferred is minimized, and the influence on the print image quality can be minimized.

  The pressing force acting on the star wheel 42 biased through the shaft is preferably 49.03325 mN to 294.1995 mN (5 gf to 30 gf), more preferably 98.0665 mN to 196.133 mN (10 gf to 20 gf). This is because the paper cannot be sufficiently pressed if it is smaller than 49.03325 mN (5 gf), and the paper is damaged if it is larger than 294.1995 mN (30 gf).

  In the case where a star wheel group is constituted by a plurality of star wheels 42, it is desirable that the star wheels be supported by a common shaft, and the distance between the star wheels 42 is 50 mm or less in order to suppress local floating and deformation of the paper. It is preferable that

  Further, when the printing area is large, it is desirable to divide the shaft into a plurality of parts and to support the plurality of star wheels 42 respectively. This is because the shaft bends and the star wheel 42 biases the paper non-uniformly, making it impossible to suppress local lifting or deformation of the paper.

  As the transport roll 40, any conventionally known transport roll can be applied. In order to reliably transmit the driving force to the sheet, a sheet having a large surface friction coefficient and excellent wear resistance is preferable. For example, a rubber roll in which rubber is coated on the outer peripheral surface of a metal roll and a ceramic roll in which ceramic powder is coated on the outer peripheral surface of a metal roll are conceivable.

  Next, the printing liquid (ink, treatment liquid) will be described.

  As the printing liquid, it is preferable to use a colored ink containing at least a pigment, a water-soluble solvent, and water, and a treatment liquid having an action of aggregating the pigment of the ink. In the present embodiment, the treatment liquid is used separately from the ink, but may be used as an ink (for example, yellow ink) by containing a pigment. Here, the means (process) for coarsely aggregating the pigment means bringing the treatment liquid into contact with the ink. That is, in the present embodiment, the means indicates the recording head 28T.

  The ink includes at least a pigment, a water-soluble solvent, and water. The pigment preferably has a size before aggregation of the pigment of 10 to 200 nm, and the size of the aggregate aggregated coarsely by the treatment liquid is 0.5 μm or more. For this reason, a high image quality density is obtained, and the pigment is hardly absorbed by the liquid absorbing device, so that it is possible to effectively absorb the excess ink.

  As the pigment, any of organic pigments and inorganic pigments can be used. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. In addition to black, cyan, magenta and yellow primary pigments, special color pigments such as red, green, blue, brown and white, metallic luster pigments such as gold and silver, colorless or light color extender pigments, plastic pigments, etc. May be used. In addition, a newly synthesized pigment may be used for the present invention.

Specific examples of pigments include Raven7000, Raven5750, Raven5250, Raven5000 ULTRAII, Raven3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1190 ULTRAII, Raven1125, Raven1170, Raven1170, Raven1170, Raven1170, Raven1170
Regal 400R, Regal 330R, Regal 660R, Mogul L, Black Pearls L, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 (manufactured by Cabot Corporation)
Color Black FW1, Color Black FW2, Color Black FW2V, Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color Black S160, Color Black 35P, PrintP35P, Color Black SFW, Color Black S160, Color Black S160, Color Black S160, Color Black Black 5, Special Black 4A, Special Black 4 (manufactured by Degussa),
No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (Mitsubishi Chemical Corporation)
However, it is not limited to these.

Further, C.I. I. Pigment Blue-1, -2, -3, -15, -15: 1, -15: 2, -15: 3, -15: 4, -16, -22, -60, and the like. It is not limited.
For the magenta color, C.I. I. Pigment Red-5, -7, -12, -48, -48: 1, -57, -112, -122, -123, -146, -168, -184, -202, and the like. It is not limited.
Yellow is C.I. I. Pigment Yellow-1, -2, -3, -12, -13, -14, -16, -17, -73, -74, -75, -83, -93, -95, -97, -98, -114, -128, -129, -138, -151, -154, and the like, but are not limited thereto.

  A pigment that can be self-dispersed in water can also be used as the pigment. A pigment that can be self-dispersed in water is a pigment that has many water-solubilizing groups on the pigment surface and can be stably dispersed in water without the presence of a polymer dispersant. Specifically, for example, by applying a surface modification treatment such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, oxidation / reduction treatment, etc. to a normal so-called pigment, A dispersible pigment is obtained.

  The following criteria were used as criteria for judging whether or not this “pigment capable of being self-dispersed in water”. That is, 95 parts by mass of water and 5 parts by mass of pigment are added and dispersed using an ultrasonic homogenizer, and this dispersion is left in a glass bottle for one day. For the dispersion, before and after standing, the pigment concentration of the one-third volume dispersion from the top is measured. A pigment concentration that is 98% or more of the pigment concentration after being left is determined to be a “pigment that can be self-dispersed in water”.

  As pigments that can be self-dispersed in water, in addition to pigments that have been surface-modified to the above pigments, Cab-o-jet-200, Cab-o-jet-300, IJX-253, manufactured by Cabot Corporation, Commercially available self-dispersing pigments such as IJX-266, IJX-444, IJX-273, IJX-55, Microjet Black CW-1, CW-2 manufactured by Orient Chemical Co., etc. can also be used.

  When a pigment that is self-dispersible in water is used as the pigment, excellent results in terms of long-term storage properties and the like tend to be obtained. This is considered to be because pigments that are self-dispersible in water are not easily affected by other additives. Further, when a pigment that is self-dispersible in water is used as the pigment, the ink may contain a polymer substance such as a polymer dispersant.

  The pigment is used in the range of 0.5 to 20% by mass, preferably 1 to 10% by mass, based on the ink mass. When the amount of pigment in the ink is less than 0.5% by mass, a sufficient optical density may not be obtained, and when the amount of pigment is more than 20% by mass, the ink ejection characteristics are unstable. There was a case.

  A polymer dispersant may be added to the ink to disperse the pigment. In addition, a polymer dispersant may be added as a polymer substance when a pigment that can be self-dispersed in water is used. As the polymer dispersant, a nonionic compound, an anionic compound, a cationic compound, an amphoteric compound and the like can be used. For example, a copolymer of a monomer having an α, β-ethylenically unsaturated group can be used.

  Specifically, as a monomer having an α, β-ethylenically unsaturated group, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid mono Ester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α -Styrene derivatives such as methylstyrene and vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylate, acrylic acid Glycol ester, methacrylic acid alkyl esters, methacrylic acid phenyl ester, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl esters, maleic acid dialkyl ester and the like.

  A copolymer obtained by copolymerizing a single monomer or a plurality of monomers having the α, β-ethylenically unsaturated group is used as a polymer dispersant. Specifically, polyvinyl alcohol, polyvinyl pyrrolidone, styrene-styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer. Polymer, vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, alkyl acrylate ester-acrylic acid copolymer, alkyl methacrylate-methacrylic acid, styrene-alkyl methacrylate-methacrylic acid copolymer Examples thereof include a polymer, a styrene-alkyl acrylate ester-acrylic acid copolymer, a styrene-methacrylic acid phenyl ester-methacrylic acid copolymer, and a styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer.

  The polymer dispersant preferably has a weight average molecular weight of 2000 to 15000. When the molecular weight of the polymer dispersant is less than 2000, there is a case where the pigment is not stably dispersed. On the other hand, when the molecular weight exceeds 15000, there is a case where the viscosity of the ink is increased and the ejection property is deteriorated. . A more preferred weight average molecular weight is 3500 to 10,000.

  The polymer dispersant is preferably added in the range of 0.1 to 3% by mass with respect to the ink. When the amount added exceeds 3% by mass, the ink viscosity increases and the ink ejection characteristics sometimes become unstable. On the other hand, when the addition amount was less than 0.1% by mass, there was a case where the dispersion stability of the pigment was lowered. More preferably, it is 0.15-2.5 mass% as addition amount as a polymer dispersing agent, More preferably, it is 0.2-2 mass%.

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

  It is preferable to use at least one water-soluble organic solvent. The content of the water-soluble organic solvent is 1 to 60% by mass, preferably 5 to 40% by mass. When the amount of the water-soluble organic solvent in the ink is less than 1% by mass, a sufficient optical density may not be obtained. Conversely, when the amount is more than 60% by mass, the ink viscosity increases. In some cases, the ink ejection characteristics become unstable.

  The ink may contain a surfactant. As the surfactant, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used. An anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant Any of the agents may be used. Moreover, the said polymer dispersing agent can also be used as surfactant.

Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, sulfuric acid of higher alcohol ether. Examples include ester salts and sulfonates, higher alkyl sulfosuccinates, higher alkyl phosphate esters, phosphate esters of higher alcohol ethylene oxide adducts, such as dodecyl benzene sulfonate and ketyl benzene sulfonate. , Isopropyl naphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol disulfonate, etc. are also effectively used. .
Nonionic surfactants include, for example, polypropylene glycol ethylene oxide adduct, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, Examples include sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkylolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, aliphatic alkanolamide, glycerin ester, sorbitan ester and the like.
Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like, such as dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethylimidazoline, Examples include lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride, and the like.
In addition, silicone surfactants such as polysiloxane oxyethylene adducts, fluorine surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers, spikrispolic acid and rhamnolipids Biosurfactants such as lysolecithin can also be used.

  Among these, a nonionic surfactant is preferable from the viewpoint of dispersion stability of the pigment. From the viewpoint of permeability control, acetylene glycol, oxyethylene adduct of acetylene glycol, polyoxyethylene alkyl ether and the like are particularly preferable.

  The addition amount of the surfactant is preferably less than 10% by mass with respect to the ink, more preferably 0.01 to 5% by mass, and still more preferably 0.01 to 3% by mass. When the addition amount was 10% by mass or more, there were cases where the optical density and the storage stability of the pigment ink were deteriorated.

In addition, for the purpose of controlling properties such as ink ejection improvement, other inks include cellulose derivatives such as polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, ethylcellulose, carboxymethylcellulose, polysaccharides and derivatives thereof, other water-soluble polymers, Polymer emulsions such as acrylic polymer emulsions and polyurethane emulsions, cyclodextrins, macrocyclic amines, dendrimers, crown ethers, urea and its derivatives, acetamide and the like can be used. In order to adjust conductivity and pH, compounds of alkali metals such as potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, triethanolamine, diethanolamine, ethanolamine, 2-amino-2-methyl Nitrogen compounds such as -1-propanol, alkaline earth metal compounds such as calcium hydroxide, acids such as sulfuric acid, hydrochloric acid and nitric acid, strong acid and weak alkali salts such as ammonium sulfate, and the like can be used.
In addition, a pH buffer, an antioxidant, an antifungal agent, a viscosity modifier, a conductive agent, an ultraviolet absorber, a chelating agent, and the like can be added as necessary.

  Any treatment liquid may be used as long as it contains a component that aggregates the pigment in the ink. Specifically, for example, for an ink containing a pigment having an anionic group, an electrolyte or a cationic compound may be contained in the treatment liquid. Examples of the electrolyte that can be effectively used in the present invention include alkali metal ions such as lithium ions, sodium ions, and potassium ions, and aluminum ions, barium ions, calcium ions, copper ions, iron ions, magnesium ions, manganese ions, nickel ions, Multivalent metal ions such as tin ion, titanium ion, zinc ion, hydrochloric acid, odorous acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, acetic acid, oxalic acid, lactic acid, fumaric acid, fumaric acid, citric acid Examples thereof include organic carboxylic acids such as acids, salicylic acid and benzoic acid, and salts of organic sulfonic acids.

  Specific examples include lithium chloride, sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, sodium sulfate, potassium nitrate, sodium acetate, potassium oxalate, sodium citrate, potassium benzoate and the like. Alkali metal salts and aluminum chloride, aluminum bromide, aluminum sulfate, aluminum nitrate, sodium aluminum sulfate, potassium aluminum sulfate, aluminum acetate, barium chloride, barium bromide, barium iodide, barium oxide, barium nitrate, thioan Barium acid, calcium chloride, calcium bromide, calcium iodide, calcium nitrite, calcium nitrate, calcium dihydrogen phosphate, calcium thiocyanate, calcium benzoate, calcium acetate, calcium salicylate Cium, calcium tartrate, calcium lactate, calcium fumarate, calcium citrate, copper chloride, copper bromide, copper sulfate, copper nitrate, copper acetate, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, oxalic acid Iron, iron lactate, iron fumarate, iron citrate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium lactate, manganese chloride, manganese sulfate, manganese nitrate, manganese dihydrogen phosphate , Manganese acetate, manganese salicylate, manganese benzoate, manganese lactate, nickel chloride, nickel bromide, nickel sulfate, nickel nitrate, nickel acetate, tin sulfate, titanium chloride, zinc chloride, zinc bromide, zinc sulfate, zinc nitrate, thiocyanate Examples thereof include salts of polyvalent metals such as zinc acid and zinc acetate.

  On the other hand, examples of the cationic compound include primary, secondary, tertiary and quaternary amines and salts thereof. Specific examples include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, polyamines, etc., for example, isopropylamine, isobutylamine, t-butylamine, 2-ethylhexylamine. , Nonylamine, dipropylamine, diethylamine, trimethylamine, triethylamine, dimethylpropylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, diethanolamine, diethylethanolamine, triethanolamine, tetramethylammonium chloride, tetraethylammonium Bromide, dihydroxyethyl stearylamine, 2-heptadecenyl-hydroxyethyl Imidazoline, lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridinium chloride, diallyldimethylammonium chloride polymers, diallylamine polymers include monoallylamine polymer and the like.

  Preferred electrolytes include aluminum sulfate, calcium chloride, calcium nitrate, calcium acetate, magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, tin sulfate, zinc chloride, zinc nitrate, zinc sulfate, zinc acetate, aluminum nitrate, monoallylamine heavy Examples thereof include a polymer, a diallylamine polymer, and a diallyldimethylammonium chloride polymer.

  On the other hand, for an ink containing a pigment having a cationic group on the surface, an anionic compound or the like may be contained in the treatment liquid. Examples of the anion compound that can be effectively used in the present invention include organic carboxylic acids or organic sulfonic acids, and salts thereof. Specifically, examples of the organic carboxylic acid include acetic acid, succinic acid, lactic acid, fumaric acid, citric acid, salicylic acid, benzoic acid, and the like, and an oligomer or polymer having a plurality of these basic structures may be used. Examples of the organic sulfonic acid include compounds such as benzenesulfonic acid and toluenesulfonic acid, and an oligomer or polymer having a plurality of these basic structures may be used.

  In the treatment liquid, the above compounds may be used alone or in combination of two or more. Moreover, as said compound content in a process liquid, 0.1-15 mass% is preferable, More preferably, it is used at 0.5-10 mass%.

  The treatment liquid may contain a surfactant in the same manner as the ink. About this surfactant, the thing similar to what was mentioned above is mentioned.

  The surface tension of the ink (including the treatment liquid) is preferably 20 mN / m or more and less than 60 mN / m, more preferably 22.5 mN or more and less than 40 mN / m. If the surface tension is less than 20 mN / m, the liquid may overflow on the nozzle surface and printing may not be performed normally. On the other hand, when it exceeds 60 mN / m, there are cases where the permeability is slow and the drying time is slow.

  Here, the surface tension can be measured using a surface tension meter (CVBP-Z / manufactured by Kyowa Interface Chemical Co., Ltd.) in an environment of 23 ° C. and 55% RH.

  The viscosity of the ink (including the treatment liquid) is preferably 1.2 mPa · s or more and less than 8.0 mPa · s, more preferably 1.5 mPa · s or more and less than 6.0 mPa · s. If the viscosity is less than 1.2 mPa · s, long-term reliability may be deteriorated. On the other hand, if it exceeds 8.0 mPa · s, the dischargeability may be lowered.

Here, the viscosity can be measured using TVE-20L (manufactured by Toki Sangyo Co., Ltd.) as a measuring device. At this time, the measurement conditions were a measurement temperature of 23 ° C. and a shear rate of 750 s ⁻¹ .

  Next, the operation of the inkjet recording apparatus 10 configured as described above will be described.

  When a printing operation is performed, the paper is supplied from the paper supply unit 12, and the registration adjustment unit 14 controls the posture and timing of the paper and is conveyed to the recording unit 16.

  On the other hand, in the recording unit 16, a motor (not shown) is driven, and the driving force is transmitted to all the transport rolls 40 via the flat belt.

  The paper that has reached the recording unit 16 is inserted between the transport roll 40 and the star wheel 42 that are most upstream in the transport direction. At this time, since the star wheel 42 urged by a spring (not shown) presses the paper against the transport roll 40, the transport force is reliably transmitted from the transport roll 40 to the paper, and is arranged between the recording heads 28 at a constant speed. The driving force is sequentially transmitted from the transport roll 40 and transported.

  On the other hand, when a print signal is input to the recording head 28 from the control unit of the apparatus, the heating element of the corresponding nozzle generates heat according to the print signal, and the paper is conveyed while being kept at a constant distance with respect to the nozzle surface. In contrast, ink is ejected from the nozzle.

  When printing is performed by the recording head 28, printing for one color in the corresponding portion of the paper is printed in the maximum recording area of the recording medium of the paper, and is finished. In this way, as the sheet is conveyed by the recording unit 16, printing is performed in the order of the recording heads 28T, 28K, 28C, 28M, and 28Y, and full-color printing is performed.

  At this time, since the ink is printed by the recording heads 28C to 28Y on the processing liquid printed by the recording head 28T, the pigment contained in the ink is coarsely aggregated by the processing liquid.

  Next, the liquid absorbing device 34 provided on the downstream side of each recording head absorbs the excess ink of each color ink remaining on the paper (absorbing operation).

  Then, the paper on which an image is printed with ink reaches the paper discharge unit 18 and is stored in the tray 38 via the paper discharge belt 36.

  As described above, in the present embodiment, the liquid absorbing device 34 absorbs the printing liquid remaining on the paper, but the surface in contact with the excess liquid in the liquid absorbing device 34 is made of an absorbent material. On the other hand, the excess liquid composed mainly of water absorbs well without releasing, and the ink (surplus liquid) itself does not repel. Even so, color mixing of the surplus liquid is prevented and the image quality is improved.

  In this embodiment, a two-component ink set is used to agglomerate the pigment contained in the ink, and the liquid absorption device 34 absorbs the excess liquid in a large state. (Collection) and excess liquid can be separated and absorbed, and the image quality density is also improved.

  Even if it is difficult to separate the pigment (aggregate) and the excess liquid, the absorption layer 54 in the liquid absorption device 34 has the above configuration (recovery rate, hole, hole area ratio) to absorb the pigment. Therefore, it is possible to absorb only the surplus liquid without fail.

  In the present embodiment, the recording head 28 and the liquid absorbing device 34 have a print area (absorption area) corresponding to the maximum sheet width PW of the sheet, so that the entire width of the sheet can be obtained without scanning the recording head 28. Thus, the difference in drying and permeation of the printing liquid (ink, processing liquid) landed on the paper is hardly generated, and in this state, the liquid absorbing device 34 can absorb the excess liquid of the printing liquid. Therefore, curl, cockle, and drying can be improved more effectively.

  The present embodiment can also be applied to a printing system in which unit recording heads (short heads) are arranged in the paper width.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

<Ink set 1: printing liquid used in Examples 1 and 2 and Comparative Example 1>
Appropriate amounts of a coloring material solution, a water-soluble organic solvent, a surfactant, ion-exchanged water, and the like were added so as to obtain a predetermined composition, and the mixed solution was mixed and stirred. The obtained liquid was passed through a 5 μm filter to obtain a desired liquid.

(Black ink)
・ Cabojet-300: 4% by mass
(Cabot Corporation: self-dispersing pigment / carboxylic acid group)
Styrene-acrylic acid-sodium acrylate copolymer: 0.5% by mass
・ Diethylene glycol: 15% by mass
・ Glycerin: 5% by mass
・ Urea: 5% by mass
-Acetylene glycol ethylene oxide adduct: 0.2% by mass
・ Ion exchange water: balance

(Cyan ink)
・ C. I. Pigment Blue 15: 3 4 mass (self-dispersing pigment / sulfonic acid group)
Styrene-acrylic acid-sodium acrylate copolymer: 0.5% by mass
・ Diethylene glycol: 15% by mass
Diglycerin ethylene oxide adduct: 5% by mass
・ Urea: 5% by mass
・ Isopropyl alcohol: 3% by mass
-Ion exchange water: 67.5% by mass

(Magenta ink)
・ C. I. Pigment Red 122: 4% by mass
(Self-dispersing pigment / sulfonic acid group)
・ Diethylene glycol: 10% by mass
・ N-methyl-2-pyrrolidone: 5% by mass
・ Sulfolane: 5% by mass
・ Urea: 3% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Coumaric acid (heterocyclic compound): 1% by mass
-Sodium hydroxide: 0.25 mass%
-Ion exchange water: 70.75 mass%

(Yellow ink)
・ C. I. Pigment Yellow 128: 4% by mass
(Self-dispersing pigment / sulfonic acid group)
・ Diethylene glycol: 15% by mass
・ Diethylene glycol monobutyl ether: 5% by mass
・ Urea: 3% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Furan carboxylic acid (heterocyclic compound): 1% by mass
-Sodium hydroxide: 0.25 mass%
-Ion exchange water: 70.75 mass%

(Processing liquid)
2-pyrrolidone-5-carboxylic acid: 0.15% by mass
・ Diethylene glycol: 15% by mass
Propylene glycol: 5% by mass
・ Urea: 3% by mass
-Acetylene glycol ethylene oxide adduct: 1% by mass
・ Sodium hydroxide: 0.2% by mass
-Ion exchange water: 76.65% by mass

<Ink set 2: Printing liquid used in Comparative Examples 2-3>
(Black ink)
・ C. I. Direct Black-2: 3% by mass
・ Glycerin: 10% by mass
・ Ethylene glycol: 10% by mass
・ Butyl carbitol: 4.5% by mass
-Ion exchange water: 72.5% by mass

(Cyan ink)
・ C. I. Direct Blue 199: 3.5% by mass
・ Diethylene glycol: 15% by mass
2-pyrrolidone: 10% by mass
・ Surfinol 465 (manufactured by Nissin Chemical Industry Co., Ltd.): 0.5% by mass
・ Ion exchange water: 71% by mass

(Magenta ink)
・ C. I. Direct Violet 107: 3.5% by mass
Propylene glycol: 15% by mass
・ Butyl carbitol: 3.5% by mass
N, N-bis- (2-hydroxyethyl) -2-aminoethanesulfonic acid: 1.0 part by mass NaOH: 0.2% by mass
-Ion exchange water: 66.8% by mass

(Yellow ink)
・ C. I. Acid Yellow 23: 2.5% by mass
・ Glycerin: 7% by mass
・ Ethylene glycol: 7% by mass
・ 2-Pyrrolidone: 7% by mass
Polyoxyethylene polyoxypropylene block polymer (weight average molecular weight about 3000, POE: POP = 2: 3): 1.0% by mass
・ Ion exchange water: 76% by mass

(Processing liquid)
Diglycerin ethylene oxide adduct: 10% by mass
・ Calcium nitrate tetrahydrate: 3% by mass
Surfactant (Surfinol 465 / Nisshin Chemical Co., Ltd.): 3% by mass
・ Isopropyl alcohol: 3% by mass
-Ion exchange water: 81% by mass

<Absorbing member (liquid absorbing device)>
Absorbing member A. Cellulose (quantitative filter paper No. 6 manufactured by ADVANTEC, thickness: 200 μm) is wound around a urethane resin sponge (absorbent layer), and the hydrophilic absorbent layer is extinguished.
Absorbing member B. A polyvinyl alcohol sponge having a surface average pore diameter of 20 μm and a hole area ratio of 60% was used (integrated absorber layer and hydrophilic absorbent layer).

  The contact angle with the aqueous solution on the surfaces of the absorbent members A and B is the Face CA-DT contact angle when the aqueous solution (Surfinol 465: manufactured by Nissin Chemical Co., Ltd .: 1% by mass, ion-exchanged water 99% by mass) is dropped. It was 24 degrees and 27 degrees, respectively when measured with a total. Further, a resin dispersion (polystyrene dispersion having an average particle size of 5.0 μm: 10% by mass, Surfynol 465: manufactured by Nissin Chemical Co., Ltd .: 1%, ion-exchanged water: 89% by mass) is the absorbent member A. When the filter paper and the absorbent member B were cut out to a thickness of 200 μm and filtered, the recoveries were 95% and 94%, respectively.

(Examples 1-3, Comparative Examples 1-3)
According to Table 1, after the treatment liquid was ejected onto the recording medium, each ink was ejected to form an image, and the excess ink was absorbed by the absorbing member. However, in the comparative example, the excess liquid was not absorbed by the dye ink or the absorbing member. The obtained recorded matter was evaluated for curl, cockle, and optical density. The results are shown in Table 1.

Evaluation was performed as follows.
―Curl, Kakkuru―
Curl, cockle; ◯: the highest part of the recording medium measured after 3 seconds of printing time is 5 mm or less, Δ: the highest part of the recording medium measured after 3 seconds of printing time is less than 10 mm, x: printing time The highest part of the recording medium measured after 3 seconds is 10 mm or more.

―Optical density―
Optical density: The optical density was measured by X-Rite 404 manufactured by X-Rite. ○: Optical density value is 1.3 or more, Δ: Optical density value is less than 1.3 and 1.0 or more, ×: Optical density value is less than 1

  In the results of Table 1, in Examples 1 and 2, bleeding between colors could be prevented and a good image quality was obtained, whereas in Comparative Examples 1 and 2, bleeding between colors was observed. In Comparative Example 3, because of the dye, the image density was low and the image quality was inferior.

  In the case where the pigment aggregate size is smaller than 0.5 μm, there arises a problem that the optical density is lowered. (If there is little aggregation, penetration into the paper tends to occur and the optical density decreases. When the aggregate size was 0.4 μm, the optical density decreased by 5% compared to 0.5 μm)

  As described above, according to the configuration of the present invention, it is possible to reliably absorb only the excess ink that has landed on the recording medium, improve the ink set-off, curl, curl, and drying properties, and obtain a good image. I understand.

1 is a schematic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. It is a schematic block diagram which shows an example of the liquid absorption apparatus in the inkjet recording device which concerns on embodiment of this invention. It is a perspective view which shows an example of the liquid absorber in the inkjet recording device which concerns on embodiment of this invention. It is a schematic block diagram which shows another example of the liquid absorption apparatus in the inkjet recording device which concerns on embodiment of this invention. It is a schematic block diagram which shows an example of the liquid absorption apparatus in the inkjet recording device which concerns on embodiment of this invention. 1 is a schematic configuration diagram illustrating a recording head in an inkjet recording apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 12 Paper supply part 14 Registration | registration adjustment part 16 Recording part 18 Paper discharge part 20 Stocker 22 Conveyor 24 Loop formation part 26 Guide member 28 Recording head 30 Maintenance apparatus 32 Conveyance means 34 Liquid absorption apparatus 36 Paper discharge belt 38 Tray 40 Transport Roll 42 Star Wheel 50 Metal Shaft 52 Absorber Layer 54 Hydrophilic Absorbent Layer 56 Stretching Shaft 58 Liquid Absorption Endless Belt 62 Liquid Absorption Wound Paper 70 Liquid Permeation Prevention Layer 72 Liquid Retention Layer

Claims (3)

A recording head for landing an ink containing a pigment on a recording medium;
Means for coarsely agglomerating the pigment to 0.5 μm or more substantially simultaneously with the landing of the ink after landing the ink on the recording medium;
Liquid absorbing means for absorbing excess ink remaining on the recording medium after the ink has landed on the recording medium; and
The ink jet recording apparatus, wherein the liquid absorbing means is an absorber having a hydrophilic surface in contact with the surplus liquid.   The inkjet recording apparatus according to claim 1, wherein the size of the pigment before aggregation is 10 to 200 nm. A step of landing an ink containing a pigment on a recording medium by a recording head;
A step of landing the ink on the recording medium and coarsely aggregating the pigment to 0.5 μm or more;
A step of absorbing the excess liquid by a liquid absorbing means for absorbing the excess liquid of the ink remaining on the recording medium;
Have
The ink jet recording method, wherein the liquid absorbing means is an absorber having a hydrophilic surface in contact with the excess liquid.

Images