Ink set, inkjet recording method, inkjet recording device, and maintenance liquid

Abstract

To provide an ink set including water-based inks and a maintenance liquid, with good abrasion resistance as well as reliability, especially, unlikely occurrence of ink non-ejection even when continuously used for a long period of time, capable of obtaining a stable image.SOLUTION: Provided is an ink set with water-based inks and a maintenance liquid used with the water-based inks. The water-based inks contain a pigment dispersed by action of an anionic group and resin particles having the anionic group, and the maintenance liquid contains an aminosulfonic acid.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an ink set, an inkjet recording method, an inkjet recording apparatus, and a maintenance liquid. [Background technology]

[0002] In recent years, the use of inkjet recording apparatuses has been increasing in the fields of office printing and commercial printing. Inkjet recording apparatuses are required to be capable of recording images with excellent robustness such as abrasion resistance, and to be reliable enough to obtain stable images without ink non-ejection even when used continuously for a long period of time.

[0003] One method for achieving both excellent abrasion resistance and reliability is to use a maintenance liquid. For example, Patent Document 1 proposes a method of using a maintenance liquid containing a solvent that satisfies a predetermined boiling point and SP value, and an amino acid, for an ink that contains a resin and a pigment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-17536 Summary of the Invention [Problem to be solved by the invention]

[0005] Aiming to achieve both abrasion resistance and reliability, the present inventors conducted a study using the ink and maintenance liquid proposed in Patent Document 1. As a result, with regard to reliability, it was found that when used continuously for a long period of time, ink non-ejection occurs, making it impossible to obtain stable images.

[0006]

[0010] Accordingly, an object of the present invention is to provide an ink set containing a water-based ink and a maintenance liquid, which has good abrasion resistance and is reliable, in particular, is unlikely to cause ink non-ejection even when used continuously for a long period of time, and is capable of obtaining stable images. Another object of the present invention is to provide an inkjet recording method using this ink set, and an inkjet recording apparatus and a maintenance liquid that can be used in this inkjet recording method. [Means for solving the problem]

[0007] That is, according to the present invention, there is provided an ink set comprising an aqueous ink and a maintenance liquid used together with the aqueous ink, wherein the aqueous ink contains a pigment dispersed by the action of anionic groups and resin particles having anionic groups, and the maintenance liquid contains aminosulfonic acid. Effect of the Invention

[0008] According to the present invention, it is possible to provide an ink set containing a water-based ink and a maintenance liquid, which has good abrasion resistance and is reliable, particularly in that even when used continuously for a long period of time, it is difficult for the ink to fail to eject, and it is possible to obtain stable images. Furthermore, according to the present invention, it is possible to provide an inkjet recording method using this ink set, and an inkjet recording apparatus and a maintenance liquid that can be used in this inkjet recording method. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of an inkjet recording apparatus of the present invention. [Diagram 2] FIG. 2 is a perspective view showing an example of a liquid application device. [Diagram 3] FIG. 2 is a cross-sectional perspective view showing an example of a discharge element substrate. [Figure 4] FIG. 2 is a schematic diagram showing an example of a liquid supply system. [Diagram 5]FIG. 2 is a perspective view showing an example of a capping tray. [Figure 6] FIG. 2 is a perspective view showing an example of a cleaning tray. [Figure 7] FIG. 4 is a schematic diagram showing an example of a supply system of the maintenance device. [Figure 8] FIG. 2 is a perspective view illustrating an example of a cleaning unit. [Figure 9A] FIG. 2 is a perspective view illustrating an example of a maintenance liquid deposition device. [Figure 9B] 9B is a cross-sectional view taken along line AA in FIG. 9A, illustrating an example of a maintenance liquid deposition device. [Figure 9C] 9B is a cross-sectional view taken along line BB in FIG. 9A, illustrating an example of a maintenance liquid deposition device. [Figure 10] FIG. 4 is a schematic diagram showing an example of the positional relationship between a liquid application device and a cleaning unit. [Figure 11] FIG. 11 is a schematic diagram showing an example of a cleaning operation. [Figure 12] FIG. 13 is a schematic diagram showing another example of the heating unit. [Figure 13] FIG. 11 is a schematic diagram showing another example of the fixing unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in more detail below with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is present in the ink in the form of dissociation into ions, but for convenience, it is expressed as "containing a salt". In addition, the aqueous ink and reaction liquid for inkjet printing may be simply referred to as "ink" and "reaction liquid". Physical property values ​​are values ​​at room temperature (25°C) unless otherwise specified. When "(meth)acrylic acid" and "(meth)acrylate" are written, they mean "acrylic acid, methacrylic acid" and "acrylate, methacrylate", respectively.

[0011] In the inkjet recording method, when a water-based ink containing a pigment dispersed by the action of anionic groups and resin particles having anionic groups is used continuously for a long period of time, the cause of non-ejection is considered to be as follows: The ink mist generated during recording adheres to the ejection port surface (face surface) of the recording head as an ink application device, and a solidified matter consisting of a mixture of pigment and resin particles is formed due to evaporation of water in the ink mist and heating of the recording head due to recording. The solidified matter blocks the ejection port of the recording head, causing non-ejection of the ink. At this time, the resin particles turn into a film-like solidified matter, so the solidified matter of the mixture of pigment and resin particles has extremely low dispersibility in the maintenance liquid compared to the solidified matter of only the pigment. Therefore, it is difficult to remove the solidified matter using the maintenance liquid.

[0012] Therefore, the inventors investigated a maintenance liquid that can peel off the above-mentioned solidified mixture of pigment and resin from the nozzle surface of the recording head, disperse it in the maintenance liquid, and then remove it by wiping or applying negative pressure (suction operation).

[0013] As a result of focusing on the materials used in the maintenance liquid, the inventors have found that the effect can be obtained by using a maintenance liquid containing aminosulfonic acid, which is a compound having a sulfo group and an amino group in the molecule. The reason for this is thought to be as follows.

[0014] The anionic groups are exposed on the surface of the fixed matter formed by the pigment and resin particles dispersed by the action of the anionic groups. The amino groups of the aminosulfonic acid in the maintenance liquid interact with the anionic groups, causing the aminosulfonic acid to act on the surface of the fixed matter, resulting in the surface of the fixed matter being covered with sulfo groups. The effect of the sulfo groups improves the dispersibility of the fixed matter, making it easier to disperse in the maintenance liquid, and the adsorption force to the ejection port surface is weakened, making it easier to remove the fixed matter by wiping or suction. There are other compounds that have anionic groups and cationic groups, such as amino acids, but the acid dissociation constant of the sulfo group is small, and its value is smaller than that of the carboxyl group and hydroxyl group, so the dispersibility of the fixed matter can be increased more than other compounds. Therefore, ink non-ejection is less likely to occur, and stable images can be obtained.

[0015] <Ink set, inkjet recording method, and inkjet recording apparatus> The ink set of the present invention (hereinafter also simply referred to as "ink set") is an ink set containing an aqueous ink and a maintenance liquid used together with the aqueous ink. The inkjet recording method of the present invention (hereinafter also simply referred to as "recording method") is an inkjet recording method using an ink set containing an aqueous ink and a maintenance liquid used together with the aqueous ink. The inkjet recording apparatus of the present invention (hereinafter also simply referred to as "recording apparatus") is an inkjet recording apparatus equipped with an ink set containing an aqueous ink and a maintenance liquid used together with the aqueous ink. The aqueous ink in the ink set contains a pigment dispersed by the action of an anionic group and resin particles having an anionic group. The maintenance liquid in the ink set contains aminosulfonic acid.

[0016] (Inkjet recording device) The inkjet recording apparatus will be described in detail below with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of the inkjet recording apparatus of the present invention. The inkjet recording apparatus of this embodiment is an inkjet recording apparatus that records an image on a recording medium using ink and a reaction liquid containing a reactant that reacts with the ink. The X direction, Y direction, and Z direction respectively indicate the width direction (total length direction), depth direction, and height direction of the inkjet recording apparatus. The recording medium is transported in the X direction.

[0017] The inkjet recording apparatus 100 of the embodiment shown in FIG. 1 is configured to include a recording unit 1000, a heating unit 2000, a fixing unit 3000, a cooling unit 4000, an inverting unit 5000, and a paper discharge unit 6000. In the recording unit 1000, various liquids are applied by a liquid application unit 1200 to a recording medium 1100 conveyed from a paper feeder 1400 by a conveying member 1300. In the heating unit 2000, the liquid applied to the recording medium 1100 is heated by a heating unit 2100, and volatile components such as water in the liquid are evaporated and dried. In the fixing unit 3000, a fixing member 3100 is brought into contact with the area of ​​the recording medium 1100 to which the liquid has been applied, and heated to promote fixing of the image to the recording medium 1100. The recording medium 1100 is then cooled by a cooling member 4100 of the cooling unit 4000. When an image is to be recorded on the back side following the front side (recording surface), the recording medium 1100 is first inverted by an inversion device 5100 of the inversion section 5000. Next, an image is recorded on the back side in the same manner as for the front side, and then the recording medium is transported by a transport member 6100 of the paper discharge section 6000 and stacked and stored in the recording medium storage section 6200. In addition, the liquid deposition performance of the liquid deposition device 1200 is restored by a maintenance device 1600. Here, a configuration having a heating section 2000 and a fixing section 3000 will be described as an example, but the heating section and the fixing section may be omitted depending on the recording conditions (type of ink or recording medium, recording speed, etc.).

[0018] Any recording medium may be used as the recording medium 1100. For example, recording media having ink absorbency (permeability) such as recording media without a coating layer, such as plain paper, uncoated paper, and synthetic paper, and recording media with a coating layer, such as printing paper, glossy paper, and art paper, may be used. In addition, recording media having no permeability, such as films or sheets made of resin materials such as polyvinyl chloride (PVC) and polyethylene terephthalate (PET), may be used. The basis weight (g / m2) of the recording medium 1100 may be determined by the following formula: 2 ) is 30g / m 2 More than 500g / m 2 It is preferable that the thickness is less than 50 g / m 2 More than 450g / m 2 It is even more preferable that:

[0019] [Recording Section] The recording unit 1000 includes a liquid applying device 1200. The liquid applying device 1200 includes a reaction liquid applying device 1201 and an ink applying device 1202. The reaction liquid applying device 1201 shown in FIG. 1 is an example of a unit using an inkjet type ejection head. In addition, the reaction liquid applying device may be configured using a gravure coater, an offset coater, a die coater, a blade coater, or the like. The reaction liquid may be applied by the reaction liquid applying device 1201 either before or after the ink application as long as it can come into contact with the ink on the recording medium 1100. However, in order to record high-quality images on various recording media having different liquid absorption characteristics, it is preferable to apply the reaction liquid before the ink is applied. An inkjet type ejection head (recording head) is used as the ink applying device 1202. The ejection method of the ejection head as the liquid applying device 1200 can be exemplified by a method of ejecting liquid by generating film boiling in the liquid by an electrothermal converter to form bubbles, and a method of ejecting liquid by an electromechanical converter. In the recording method and recording apparatus of the present invention, for example, by using the liquid application apparatus 1200 (ink application apparatus 1202) described above, it is possible to discharge ink from the discharge ports of the liquid application apparatus and record an image on a recording medium.

[0020] The liquid deposition device 1200 is a line head extending in the Y direction, and has ejection ports arranged in a range that covers an image recording area of ​​the widest usable recording medium. The ejection head has an ejection port surface 1207 (FIG. 3) on which ejection ports are formed on its lower side (the recording medium 1100 side), and the ejection port surface faces the recording medium 1100 at a very small distance of about a few millimeters.

[0021] A plurality of ink applicators 1202 may be provided to apply ink of each color to the recording medium 1100. For example, when recording images of each color using yellow ink, magenta ink, cyan ink, and black ink, four ink applicators 1202 for ejecting the above four types of ink are arranged side by side in the X direction. Hereinafter, the ink and the reaction liquid may be collectively referred to as "liquid".

[0022] FIG. 2 is a perspective view showing an example of a liquid applying device. The liquid applying device 1200 shown in FIG. 2 is a line head, and a plurality of ejection element substrates 1203, each having an ejection port array, are arranged in a straight line. A plurality of ejection port arrays are arranged on the ejection element substrate 1203. A protective member (hereinafter, also referred to as a "first protective member") 1224 for protecting the plurality of ejection element substrates 1203 is arranged on the outer periphery of the ejection element substrates 1203 arranged in a straight line. In addition, the liquid applying device 1200 has a first positioning portion 1225 used for positioning a capping unit described later on both ends. Specifically, a first contact portion 1225a, which is a recess having a cone-shaped inclined surface, is provided on the front side of the drawing in the longitudinal direction (Y direction) of the liquid applying device 1200. Further, a second contact portion 1225b which is a groove portion having two V-shaped flat surfaces, and a third contact portion 1225c which is a flat surface are provided on the rear side of the liquid application device 1200 in the longitudinal direction (Y direction) in the drawing.

[0023] FIG. 3 is a cross-sectional perspective view showing an example of a discharge element substrate. The discharge element substrate 1203 shown in FIG. 3 includes a discharge port forming member 1206 having a discharge port 1204 opened therein, and a substrate 1205 having discharge elements (not shown) disposed thereon. The discharge port forming member 1206 and the substrate 1205 are laminated to form a first flow path 1208 and a second flow path 1209 through which liquid flows. The first flow path 1208 is a region from an inlet 1212 through which liquid flows in from an inflow path 1210 to a portion between the discharge port 1204 and the discharge element (FIG. 4, liquid chamber 1508). The second flow path 1209 is a region from a portion between the discharge port 1204 and the discharge element (FIG. 4, liquid chamber 1508) to an outlet 1213 through which liquid flows out to an outlet path 1211. For example, by creating a pressure difference between the inlet 1212 and the outlet 1213, such as the inlet 1212 having a high pressure and the outlet 1213 having a low pressure, liquid can be made to flow from the high pressure to the low pressure (in the direction of the arrow in FIG. 3). The liquid that has passed through the inlet 1210 and the inlet 1212 enters the first flow path 1208. Then, the liquid that has passed through the portion between the outlet 1204 and the ejection element (liquid chamber 1508 in FIG. 4) flows through the second flow path 1209 and the outlet 1213 to the outlet path 1211.

[0024] [Supply system] FIG. 4 is a schematic diagram showing an example of a supply system for liquid such as ink. The supply unit 1500 of the liquid deposition apparatus 1200 shown in FIG. 4 is configured to include a first circulation pump (high pressure side) 1501, a first circulation pump (low pressure side) 1502, a sub-tank 1503, and a second circulation pump 1505. The sub-tank 1503 connected to a main tank 1504, which is a liquid storage unit, has an air communication port (not shown) and can discharge air bubbles mixed in the liquid to the outside of the circulation system. The sub-tank 1503 is also connected to a refill pump 1506. The liquid is consumed in the liquid deposition apparatus 1200 by discharging (discharging) the liquid from the discharge port for image recording, suction recovery, etc. The refill pump 1506 transfers the liquid corresponding to the consumed amount from the main tank 1504 to the sub-tank 1503.

[0025] The first circulation pump (high pressure side) 1501 and the first circulation pump (low pressure side) 1502 cause the liquid in the liquid deposition device 1200, which is caused to flow out from a connection part (inlet part) 1507, to flow into a sub tank 1503. It is preferable to use a positive displacement pump having a quantitative liquid delivery capability as the first circulation pump (high pressure side) 1501, the first circulation pump (low pressure side) 1502, and the second circulation pump 1505. Examples of such a positive displacement pump include a tube pump, a gear pump, a diaphragm pump, and a syringe pump. When the ejection element substrate 1203 is driven, the first circulation pump (high pressure side) 1501 and the first circulation pump (low pressure side) 1502 can cause the liquid to flow from a common inlet channel 1514 toward a common outlet channel 1515.

[0026] The negative pressure control unit 1509 includes two pressure adjustment mechanisms with mutually different control pressures. The pressure adjustment mechanism (high pressure side) 1510 and the pressure adjustment mechanism (low pressure side) 1511 are connected to a common inflow channel 1514 and a common outflow channel 1515 in the ejection element substrate 1203 via a supply unit 1513 provided with a filter 1512 for removing foreign matter from the liquid. The ejection element substrate 1203 is provided with the common inflow channel 1514, the common outflow channel 1515, and the inflow channel 1210 and the outflow channel 1211 that communicate with the liquid chamber 1508, which is a portion between the ejection port 1204 and the ejection element (not shown). Since the inflow channel 1210 and the outflow channel 1211 communicate with the common inflow channel 1514 and the common outflow channel 1515, respectively, a flow (arrow in FIG. 4) occurs in which part of the liquid flows from the common inflow channel 1514 through the inside of the liquid chamber 1508 to the common outflow channel 1515. The arrows in Fig. 3 indicate the flow of liquid inside the liquid chamber 1508. That is, as shown in Fig. 3, the liquid in the first flow path 1208 flows to the second flow path 1209 via the gap between the ejection port 1204 and the ejection element.

[0027] 4, a pressure adjustment mechanism (high pressure side) 1510 is connected to the common inflow channel 1514, and a pressure adjustment mechanism (low pressure side) 1511 is connected to the common outflow channel 1515, so that a pressure difference occurs between the inflow channel 1210 and the outflow channel 1211. As a result, a pressure difference also occurs between an inlet 1212 (FIG. 3) communicating with the inflow channel 1210, and an outlet 1213 (FIG. 3) communicating with the outflow channel 1211. When liquid is caused to flow by the pressure difference between the inlet 1212 and the outlet 1213, it is preferable to control the flow velocity (mm / s) of the liquid to be 0.1 mm / s or more and 10.0 mm / s or less.

[0028] [Transport system] As shown in FIG. 1, the recording unit 1000 is configured to include a liquid applying device 1200 and a conveying member 1300 that conveys the recording medium 1100. The liquid applying device 1200 applies a reaction liquid and ink to a desired position of the recording medium 1100 conveyed by the conveying member 1300. Each liquid applying device 1200 receives an image signal of recording data and applies the necessary reaction liquid and ink to each position. FIG. 1 shows the conveying member 1300 in the form of a conveying belt, but a spur, a conveying drum, or the like may be used as long as it has the function of conveying the recording medium 1100. In order to improve the conveying accuracy, a material that can fix the recording medium 1100 can be used as the conveying member 1300. Specifically, a method of providing a hole in the conveying member 1300 and fixing the recording medium 1100 by sucking from the back side, a method of forming the conveying member 1300 from an appropriate material and fixing the recording medium 1100 by electrostatic adsorption, etc. can be mentioned.

[0029] [Maintenance system] As shown in FIG. 1, the recording unit 1000 is configured to include a maintenance device 1600. The maintenance device 1600 performs maintenance to restore the liquid ejection performance of the liquid deposition device 1200. The maintenance device 1600 is configured to include, for example, a capping unit 1701 (see FIG. 5) that protects the ejection port surface 1207 (see FIG. 3) and a cleaning unit 1801 (see FIG. 6) that cleans the ejection port surface 1207 (see FIG. 3). The maintenance device 1600 further includes a drive device and rails (not shown), and is configured to be movable in the X direction in FIG. 1 along the rails. When maintenance of the liquid deposition device 1200 is performed, the maintenance device moves directly below the liquid deposition device 1200, and when maintenance of the liquid deposition device 1200 is not performed, the maintenance device moves to a position retreated from directly below the liquid deposition device 1200.

[0030] Next, the configuration of the maintenance device 1600 will be described. The maintenance device 1600 shown in Fig. 1 is equipped with a capping tray 1700 having a capping unit 1701 (see Fig. 5) and a cleaning tray 1800 having a cleaning unit 1801 (see Fig. 6). The capping tray 1700 and the cleaning tray 1800 are configured to be movable in the longitudinal direction of the inkjet recording apparatus (X direction in Fig. 1) by a driving motor (not shown) and rails provided on the housing of the inkjet recording apparatus 100.

[0031] FIG. 5 is a perspective view showing an example of a capping tray 1700. The capping tray 1700 has a plurality of capping units 1701 for protecting the ejection port surfaces of the reaction liquid applying device 1201 and the ink applying device 1202, which are the liquid applying device 1200. The capping unit 1701 has a plurality of spherical second positioning portions 1702 used for positioning the capping unit 1701 with respect to the liquid applying device 1200. One second positioning portion 1702 is disposed at one end in the longitudinal direction of one capping unit 1701, and two second positioning portions 1702 are disposed at the other end. The positions of the liquid applying device 1200 and the capping unit 1701 are regulated by abutment between the first positioning portions 1225 (see FIG. 2) provided at both ends of the liquid applying device 1200 and the second positioning portions 1702 of the capping unit 1701. The capping unit 1701 covers the discharge port surface side of the liquid deposition apparatus 1200 when the liquid deposition apparatus 1200 is not in use, thereby protecting the discharge port surface 1207 (see FIG. 3) of the liquid deposition apparatus 1200 and enabling suction by a negative pressure deposition apparatus described later.

[0032] A capping liquid supply flow path 1703 shown in Fig. 5 is a flow path through which the maintenance liquid is supplied to the capping unit 1701. As shown in Fig. 5, the capping liquid supply flow path 1703 of the capping unit 1701 corresponding to each liquid deposition device 1200 includes a plurality of cap upstream three-way valves 1704, and has a three-way valve upstream flow path and a three-way valve downstream flow path. The upstream side (the maintenance liquid sub-tank 1603 (see Fig. 7) side) of each cap upstream three-way valve 1704 is the three-way valve upstream flow path, and the downstream side is the three-way valve downstream flow path. The plurality of cap upstream three-way valves 1704 are supported by a three-way valve support member 1705 by a fixing method not shown.

[0033] FIG. 6 is a perspective view showing an example of a cleaning tray 1800. The cleaning tray 1800 has a plurality of cleaning units 1801 for cleaning the ejection port surface 1207. The cleaning tray 1800 also has a plurality of spherical third positioning parts 1802 used for positioning the cleaning units 1801 with respect to the liquid deposition device 1200. The third positioning parts 1802 are arranged on beam members 1803a and 1803b arranged on both sides of the width direction (Y direction in FIG. 1) of the recording medium 1100 to be conveyed inside the cleaning tray 1800. Three third positioning parts 1802 are required to position one liquid deposition device 1200 with respect to the cleaning tray 1800. Specifically, one third positioning part 1802 is arranged on the beam member 1803a on the front side of the drawing in the Y direction in FIG. 1 in the cleaning tray 1800, and two third positioning parts 1802 are arranged on the beam member 1803b on the back side of the drawing. The positions of the liquid deposition apparatus 1200 and the cleaning tray 1800 are regulated by abutment between first positioning portions 1225 provided on both ends of the liquid deposition apparatus 1200 and third positioning portions 1802 of the cleaning tray 1800 .

[0034] The configuration for positioning the first positioning portion 1225 and the second positioning portion 1702 and / or the third positioning portion 1802 is not limited to a configuration using a spherical positioning portion. For example, a configuration in which a part of the liquid deposition device 1200 is abutted against the inside of the capping unit 1701 or the cleaning tray 1800 may be used. Also, for example, a configuration in which the liquid deposition device 1200 and a hole provided in the capping unit 1701 or the cleaning tray 1800 are positioned using a pin may be used.

[0035] The cleaning unit 1801 includes a maintenance liquid applying device 1850, a liquid removing device 1860, and a negative pressure applying device 1870. The maintenance liquid applying device 1850 applies the maintenance liquid to the ejection port surface 1207 of the liquid applying device 1200. The liquid removing device 1860 is a device for removing the maintenance liquid from the ejection port surface 1207 of the liquid applying device 1200, and is a device that can remove the liquid, paper powder, maintenance liquid, and the like that are attached to the liquid applying device 1200. The negative pressure applying device 1870 is a device for removing ink that has adhered to the ejection port and removing bubbles in the first flow path 1208 and the second flow path 1209 by applying a negative pressure to the ejection port surface 1207 of the liquid applying device 1200 and sucking the ink. As shown in FIG. 6, the cleaning unit 1801 is configured to be movable along a wiping direction (direction D in FIG. 6) that is perpendicular to the transport direction of the recording medium 1100. The cleaning unit 1801 removes the liquid, paper powder, maintenance liquid, and the like from the ejection port surface 1207 of the liquid deposition device 1200 by means of a maintenance liquid deposition device 1850 , a liquid removal device 1860 , and a negative pressure deposition device 1870 .

[0036] (Maintenance equipment supply system) 7, a supply system such as a maintenance liquid supply path, a suction flow path, and a waste liquid flow path of the maintenance device 1600 will be described. The maintenance liquid is sent from a maintenance liquid pack 1601 to a maintenance liquid sub-tank 1603 by a pump 1602. From the maintenance liquid sub-tank 1603, the maintenance liquid can be sent to the capping unit 1701, the maintenance liquid deposition device 1850, and the negative pressure application device 1870 by a maintenance liquid supply pump 1604. The maintenance liquid supply pump 1604 is provided in a maintenance liquid and negative pressure supply unit 1650 (Y: yellow, M: magenta, C: cyan, Bk: black, P: reaction liquid) corresponding to the liquid deposition device 1200. In addition, the timing of supplying the maintenance liquid to the capping unit 1701, the maintenance liquid deposition device 1850, and the negative pressure application device 1870 can be controlled by each of opening and closing valves 1605, 1606, and 1607.

[0037] Negative pressure is applied to the capping unit 1701 and the negative pressure applying device 1870 by a suction pump 1616 connected to a negative pressure tank 1615. Negative pressure can be applied to each of the capping units 1701 and each of the negative pressure applying devices 1870 through the opening and closing valves 1617, 1618, and 1619 via each negative pressure tank 1615. When liquid is sucked using the capping unit 1701 and the negative pressure applying device 1870, waste liquid sucked from the liquid applying device 1200 is stored in the drain sub-tank 1613 from the negative pressure tank 1615 by the pump 1614. Then, the waste liquid is stored in the waste liquid tank 1611 from the drain sub-tank 1613 by the pump 1612. In addition, a collection tray 1630 for collecting the maintenance liquid overflowing from the maintenance liquid applying device 1850 is provided in the supply system, and the excess maintenance liquid is sent to the drain sub-tank 1613 by the pump 1621. The capacity of the waste liquid tank 1611 is detected by a waste liquid tank detection sensor (not shown), and when the capacity approaches the upper limit, the user is prompted to replace the waste liquid tank 1611.

[0038] The waste liquid from the reaction liquid deposition device 1201 is accommodated in a drain sub-tank 1633 for the reaction liquid by a pump 1634, separately from the waste liquid flow path from the ink deposition device 1202, and is stored in a waste liquid tank 1631 for the reaction liquid by a pump 1632. This prevents the reaction liquid and the ink from mixing in the waste liquid flow path, making it possible to suppress clogging of the flow path due to ink solidifying in the flow path.

[0039] As in the supply system described above, the maintenance liquid and negative pressure supply unit 1650 corresponding to each liquid deposition device is provided with a maintenance liquid supply pump 1604 and on-off valves 1605, 1606, and 1607 for controlling the supply of maintenance liquid to each flow path. The maintenance liquid and negative pressure supply unit 1650 is also provided with a negative pressure tank 1615, a suction pump 1616 for suction, and on-off valves 1617, 1618, and 1619 for controlling the application of negative pressure to each part. The maintenance liquid and negative pressure supply unit 1650 may be provided with a filter 1622.

[0040] (Operation to prevent flow path sticking of maintenance device) The operation of the maintenance device for preventing the flow passage from sticking will be described with reference to FIG. 7. When the liquid is sucked from the liquid application device 1200 using the capping unit 1701, the liquid is prevented from sticking in the capping unit 1701 and in the supply system leading to the waste liquid tanks 1611 and 1631, causing blockage of the flow passage. For this purpose, after sucking the liquid, the liquid application device 1200 is separated from the capping unit 1701, and then an empty suction operation is performed. As a result, the liquid inside the capping unit 1701 and in the flow passage is sent to the waste liquid tanks 1611 and 1631, and then the cap upstream three-way valve 1704 is opened, and the maintenance liquid is filled in the capping unit 1701 through the valve. Next, the empty suction operation is performed in the same manner to send the maintenance liquid to the waste liquid tanks 1611 and 1631, thereby cleaning the inside of the capping unit 1701 and in the flow passage, and preventing sticking in the supply system. In order to achieve a high level of sticking prevention, it is preferable to perform the cleaning process using the maintenance liquid multiple times, particularly about 3 to 5 times.

[0041] The liquid can be preliminarily discharged from the liquid deposition device 1200 to the capping unit 1701. The preliminarily discharge is an operation performed to stabilize the discharge state when replacing the liquid deposition device 1200 or performing maintenance on the liquid deposition device, or to normalize the discharge state at any timing, such as before the start of recording, during recording, or after recording. When performing preliminarily discharge with the maintenance device, the cap upstream three-way valve 1704 is opened, the capping unit 1701 is filled with the maintenance liquid, and then a predetermined amount of liquid is preliminarily discharged from the liquid deposition device 1200 into the capping unit 1701. Thereafter, an idle suction operation is performed to send the liquid inside the capping unit 1701 and in the flow path together with the maintenance liquid to the waste liquid tanks 1611 and 1631. If necessary, a flow path cleaning process may be performed in the same manner as described above, in which the cap upstream three-way valve 1704 is opened, the capping unit 1701 is filled with the maintenance liquid, and then an idle suction operation is performed in the same manner to send the maintenance liquid to the waste liquid tanks 1611 and 1631.

[0042] (Capping of liquid application device) The capping operation of the liquid applying device will be described with reference to FIG. 5 and FIG. 7. When the recording operation is completed and no recording is performed for a certain period of time, the liquid applying device 1200 preferably caps the discharge port surface to suppress evaporation in order to suppress adhesion of the liquid in the flow path. The liquid applying device 1200 can be abutted against the capping unit 1701 shown in FIG. 5 to be capped. Before the capping unit 1701 is abutted against the capping unit 1701, the cap upstream three-way valve 1704 shown in FIG. 7 is opened to fill the capping unit 1701 with the maintenance liquid. Then, the liquid applying device 1200 is abutted against the capping unit 1701 to cap it, thereby effectively suppressing adhesion of the liquid in the flow path of the liquid applying device 1200. Even if the capping state continues for a certain period of time, if the liquid applying device 1200 has a liquid circulation mechanism (not shown) in the flow path, the liquid can be stably discharged from the initial stage of resuming recording by the liquid circulation operation in the flow path in the recording preparation operation.

[0043] (Cleaning unit configuration) FIG. 8 is an enlarged perspective view of the dashed line portion shown in FIG. 6, and shows the configuration of a cleaning unit 1801 arranged in a cleaning tray 1800. The cleaning unit 1801 is configured with a maintenance liquid applying device 1850, a liquid removing device 1860, and a negative pressure applying device 1870. The liquid removing device 1860 is configured with a wiper blade 1861 formed of a flexible material such as urethane rubber. FIG. 8 shows an example in which two wiper blades are arranged, but the size and number of wiper blades can be set in consideration of the structure and removal performance of the discharge port surface of the liquid applying device 1200. The negative pressure applying device 1870 is formed of a flexible member 1871, and it is preferable to select a material that can efficiently remove liquid, bubbles, etc. by negative pressure when it comes into contact with the discharge port surface 1207 of the liquid applying device 1200.

[0044] 9A to 9C are schematic diagrams showing a configuration of a maintenance liquid deposition device 1850. FIG. 9A is a perspective view showing the maintenance liquid deposition device 1850. FIG. 9B is a cross-sectional view of the maintenance liquid deposition device 1850 shown in FIG. 9A taken along line AA. FIG. 9C is a cross-sectional view of the maintenance liquid deposition device 1850 shown in FIG. 9A taken along line BB. The maintenance liquid deposition device 1850 has a flexible maintenance liquid deposition member 1851. The maintenance liquid deposition device 1850 also has a maintenance liquid deposition member holder 1852 that holds the maintenance liquid deposition member 1851 and has a flow path formed therein for supplying the maintenance liquid to the inside of the maintenance liquid deposition member 1851. The maintenance liquid deposition device 1850 also has a maintenance liquid deposition member cover 1853 that covers the maintenance liquid deposition member 1851. The maintenance liquid deposition member 1851 is held between the maintenance liquid deposition member holder 1852 and the maintenance liquid deposition member cover 1853. 9B, a maintenance liquid supply tube 1854 is connected to the maintenance liquid application member holder 1852. The maintenance liquid supplied from the maintenance liquid supply tube 1854 passes through the maintenance liquid application member holder 1852, and is applied to the discharge port surface 1207 by the maintenance liquid application member 1851. The maintenance liquid application device 1850 also has a biasing member 1855, and while the maintenance liquid is being applied to the discharge port surface 1207, the maintenance liquid application member 1851 is pressed against the discharge port surface 1207. The maintenance liquid application device 1850 is attached to the cleaning tray 1800 by a support portion 1857.

[0045] As shown in FIGS. 9A to 9C, the maintenance liquid application member 1851 has a notch in a part of the surface that contacts the ejection port surface 1207. The maintenance liquid application member 1851 has a surface 1851a (first surface) on the upstream side (+Y direction) and a surface 1851c (third surface) on the downstream side (-Y direction) with respect to the application direction of the maintenance liquid, and also has a surface 1851b (second surface) that intersects with the first surface 1851a. When the maintenance liquid is applied to the ejection port surface 1207, the first surface 1851a on the upstream side with respect to the application direction of the maintenance liquid and the second surface 1851b that intersects with the first surface 1851a come into contact with the ejection port surface 1207 and are pressed against it. At this time, a gap 1856 is formed between the third surface 1851c on the downstream side with respect to the application direction of the maintenance liquid and the ejection port surface 1207. In the illustrated example, the contact length of the first surface 1851a with the ejection port surface 1207 is longer than the contact length of the second surface 1851b with the ejection port surface 1207, making it easier for the maintenance liquid application member 1851 to conform to the surface shape of the ejection port surface 1207.

[0046] 9B, a first surface 1851a on the upstream side in the direction in which the maintenance liquid is applied, which contacts the ejection port surface 1207, is formed to be thinner than a base portion 1851d thereof. As shown in FIG. 9C, a second surface 1851b that intersects with the first surface 1851a on the upstream side in the direction in which the maintenance liquid is applied, is formed to be thinner than a base portion 1851e thereof. With these configurations, the tip of the maintenance liquid application member 1851 has a thin wall thickness and is easily deformed. Therefore, when the maintenance liquid application member 1851 is pressed against the ejection port surface 1207 having projections and recesses, it is possible for the maintenance liquid application member 1851 to follow the projections and recesses of the ejection port surface 1207.

[0047] 10 is a schematic diagram showing the positional relationship between the liquid deposition device and the cleaning unit. In this example, a state in which a maintenance liquid deposition device 1850, a liquid removal device 1860, and a negative pressure application device 1870 are in contact with the discharge port surface 1207 of the liquid deposition device 1200 is shown. The maintenance liquid deposition device 1850, the liquid removal device 1860, and the negative pressure application device 1870 are each configured to be able to come into contact with or separate from the discharge port surface 1207. Therefore, each of these can be swept in the longitudinal direction of the liquid deposition device 1200 to deposit maintenance liquid, remove the liquid or a mixture of the maintenance liquid by suction, and wipe the liquid deposition device 1200.

[0048] The cleaning process of the discharge port surface 1207 of the liquid deposition device 1200 will be described. As an example of how cleaning can be performed efficiently, FIG. 11 shows a schematic diagram of an example of the cleaning operation of the liquid deposition device 1200. The present invention is not limited to this method. First, a maintenance liquid deposition device 1850 is swept in a state in which it is in contact with the liquid deposition device 1200, so that the maintenance liquid is deposited on the discharge port surface 1207 and the first protective member 1224 (FIG. 11(a)). Next, a liquid removal device 1860 is swept in a state in which it is in contact with the discharge port surface 1207 and the first protective member 1224, so that the liquid adhering to the discharge port surface 1207 of the liquid deposition device 1200 together with the maintenance liquid previously deposited is wiped off (FIG. 11(b)). By sweeping the negative pressure applying device 1870 while it is in contact with the discharge port surface 1207 of the liquid applying device 1200, it is possible to remove liquid that has solidified near the discharge ports present on the discharge port surface 1207 and to remove bubbles within the flow paths (FIG. 11(c)). Each step in FIG. 11(a) to (c) may be performed in this order, or each step may be performed in parallel.

[0049] Furthermore, when the liquid removing device 1860 is swept while in contact with the ejection port surface 1207 and the first protective member 1224 to wipe off liquid and the like adhering to the ejection port surface 1207, the sweeping direction of the liquid removing device 1860 may be either the +Y direction or the -Y direction in Fig. 6. Similarly, when the negative pressure applying device 1870 is swept while in contact with the ejection port surface 1207 to remove solidified liquid present on the ejection port surface 1207, the sweeping direction of the negative pressure applying device 1870 may be either the +Y direction or the -Y direction in Fig. 6.

[0050] The scanning speed of the maintenance liquid applicator 1850 is preferably 40 mm / s or more and 120 mm / s or less. The scanning speed of the liquid remover 1860 is preferably 50 mm / s or more and 150 mm / s or less. The scanning speed of the negative pressure applicator 1870 is preferably 1.0 mm / s or more and 15.0 mm / s or less. In addition, the negative pressure applied by the negative pressure applicator 1870 is preferably -20 kPa or less.

[0051] For example, by employing the above-mentioned configuration related to the maintenance system, the recording method of the present invention preferably includes the following steps. That is, it is preferable to include a step of ejecting water-based ink from the ejection ports of a liquid application device to record an image on a recording medium; a step of applying a maintenance liquid to an ejection port surface having ejection ports in the liquid application device; and a step of cleaning the ejection port surface of the liquid application device. It is also preferable to carry out a step of cleaning the ejection port surface after the step of applying the maintenance liquid to the ejection port surface. It is also preferable that in the step of cleaning the ejection port surface of the liquid application device (cleaning step), the ejection port surface is cleaned by a wiper blade and by applying negative pressure.

[0052] Also, it is preferable that the liquid applying device 1200 has a protective member (hereinafter, also referred to as "second protective member") for protecting the discharge port surface 1207 of the discharge element substrate 1203. That is, it is preferable that the liquid applying device 1200 has a second protective member for protecting the discharge port surface 1207. The second protective member can have an opening corresponding to a discharge port array in which a plurality of discharge ports 1204 are arranged in a predetermined direction. Specifically, a second protective member having a rectangular opening corresponding to the discharge port array is bonded to the discharge port surface 1207 by an adhesive. With such a configuration, when the recording medium 1100 floats up during transportation, the second protective member plays a role of suppressing contact between the recording medium 1100 and the discharge element substrate 1203, and damage to the liquid applying device 1200 can be suppressed. Therefore, it is preferable that the second protective member has sufficient mechanical strength, and for example, a metal material such as stainless steel or aluminum, silicone, or alumina can be suitably used as a material.

[0053] The second protective member has rectangular openings formed therein corresponding to the rows of ejection ports. The openings can be formed to correspond to any number of rows of ejection ports, but it is preferable that one second protective member has a plurality of openings. It is preferable that one opening is formed for one row of ejection ports.

[0054] It is also preferable that the length of the opening of the second protective member in the direction substantially intersecting with the ejection port array direction is 250 μm or more and less than the interval between adjacent ejection port arrays, and the thickness of the second protective member is less than 50 μm. This allows the maintenance device 1600 of the recording device to more suitably recover the liquid on the ejection port surface 1207 of the liquid deposition device 1200 when the maintenance device 1600 comes into contact with the liquid deposition device 1200 during maintenance.

[0055] [Heating section] As shown in Fig. 1, the heating section 2000 is configured to include a heating device 2100 and a transport member 2200. The recording medium 1100, to which the reaction liquid and ink have been applied and an image has been recorded, is heated by the heating device 2100 while being transported by the transport member 2200, thereby evaporating and drying the liquid components of the image. It is preferable to further include a drying step between the ink application step and the fixing step, in which the recording medium to which the ink has been applied is heated in a non-contact manner to dry the ink. By including such a drying step, deformation (cockling and curling) of the recording medium 1100 can be effectively suppressed.

[0056] The heating device 2100 may have any configuration as long as it can heat the recording medium 1100, and various conventionally known devices such as a hot air dryer and a heater can be used. Among them, the use of a non-contact heater such as an electric heating wire or infrared heater is preferable from the standpoint of safety and energy efficiency. In addition, if a mechanism for blowing hot air with a built-in fan for spraying heated gas onto the recording medium 1100 is used, the drying efficiency can be easily improved.

[0057] Regarding the method of heating, the recording medium 1100 may be heated from the side (recording surface (front side)) to which the reaction liquid and the ink are applied, or from the back side, or from both sides. The conveying member 2200 may be provided with a heating function. FIG. 1 shows the conveying member 2200 using a conveying belt, but a spur, conveying drum, or the like may be used as long as it has the function of conveying the recording medium 1100. From the viewpoint of suppressing deformation of the recording medium 1100 due to heating, it is preferable to have a configuration in which the recording medium 1100 is conveyed while being in close contact with the conveying member 2200 by blowing air from the heating unit 2000, or to have a mechanism for fixing the recording medium to the conveying member 2200. Specifically, a method of providing a hole in the conveying member 2200 and fixing the recording medium 1100 by suction from the back side, a method of forming the conveying member 2200 from an appropriate material, and fixing the recording medium 1100 by electrostatic adsorption, etc. can be mentioned.

[0058] The heating temperature is preferably set so as to quickly evaporate the liquid components and not to over-dry the recording medium 1100 in terms of suppressing deformation of the recording medium. The temperature of the drying means can be set so that the recording medium reaches a desired temperature, taking into consideration the conveying speed and the environmental temperature. Specifically, the temperature of the drying means (such as hot air) is preferably set to 40°C or higher and 100°C or lower, and more preferably 60°C or higher and 80°C or lower. In addition, when the recording medium 1100 is heated by blowing heated gas, the wind speed is preferably set to 1 m / s or higher and 100 m / s or lower. The temperature of the wind such as the hot air can be measured using a K-type thermocouple thermometer. A specific measuring device can be, for example, the product name "AD-5605H" (manufactured by A&D).

[0059] Fig. 12 is a schematic diagram showing another example of the heating section. Here, the difference from the heating section shown in Fig. 1 and described above will be described. The heating section 2000 shown in Fig. 12 includes a first heating device 2101 and a second heating device 2102, and a first conveying member 2201 and a second conveying member 2202 arranged opposite the first heating device 2101 and the second heating device 2102, respectively.

[0060] The first conveying member 2201 does not have a mechanism for sucking and fixing the recording medium 1100. The recording medium 1100 is pressed against the first conveying member 2201 by hot air from the first heating device 2101 to convey the recording medium 1100. This allows the recording medium 1100 to be transferred with high precision from the conveying member 1300 (FIG. 1) to the first conveying member 2201, and from the first conveying member 2201 to the second conveying member 2202. Furthermore, it is possible to reduce conveyance deviations caused by slight differences in conveying speed between the conveying member 1300 (FIG. 1) and the first conveying member 2201. On the other hand, a conveying belt having holes that can pass gas is used as the second conveying member 2202, and the recording medium 1100 is conveyed while being fixed to the second conveying member 2202 by a suction mechanism (not shown).

[0061] An air knife 2300 is disposed between the transport member 1300 (FIG. 1) and the first transport member 2201, between the first transport member 2201 and the second transport member 2202, and between the second transport member 2202 and the transport member 3200 (FIG. 1). The air pressure from the air knife 2300 prevents the leading edge of the transported recording medium 1100 from floating up. This makes it possible to prevent the leading edge of the recording medium 1100 from colliding with the first heating device 2101, the second heating device 2102, and the fixing member 3100 (FIG. 1), and to suppress the occurrence of transport failure.

[0062] The first heating device 2101 and the second heating device 2102 can have the same configuration as the above-mentioned heating device 2100. The temperatures of the first heating device 2101 and the second heating device 2102 and the wind speed when blowing heated gas for heating may be the same or different. Furthermore, heating may be performed from the first conveying member 2201 and the second conveying member 2202 as necessary.

[0063] [Fixing section] As shown in FIG. 1, the fixing unit 3000 is a contact-type heating and pressurizing mechanism having a fixing member 3100 as a fixing belt such as an endless belt and a conveying member 3200. In the fixing unit 3000, the recording medium 1100 is conveyed by the conveying member 3200, and the fixing member 3100 is brought into contact with the recording medium 1100 under pressure, and the liquid such as the reaction liquid or ink applied to the recording medium 1100 is heated. In this way, an image can be fixed on the recording medium 1100. From the recording medium 1100 on which an image has been recorded, the liquid components of the reaction liquid or ink permeate the recording medium 1100 or evaporate by passing through the heating unit 2000, and then the image is fixed in the fixing unit 3000, completing the image. By heating and pressurizing the recording medium 1100 sandwiched between the fixing member 3100 and the conveying member 3200, the image of the recording medium 1100 and the fixing member 3100 come into close contact with each other, and the image is fixed on the recording medium 1100. When a liquid such as ink containing resin particles and coloring material is used, the resin particles are softened and form a film mainly by heating in the fixing unit 3000 , and the coloring material can be bound onto the recording medium 1100 .

[0064] The fixing member 3100 may be heated by providing a heat source such as a halogen heater inside a roller that drives the fixing member 3100 as a fixing belt. Alternatively, a heat source such as an infrared heater may be provided at a location separate from the fixing member 3100. These methods may be combined. If necessary, the conveying member 3200 may be heated. The temperature of the fixing member 3100 may be set so that the surface of the recording medium has a desired temperature, taking into account the conveying speed and the environmental temperature. Specifically, the temperature of the fixing member 3100 is preferably 50° C. or higher and 120° C. or lower, and more preferably 60° C. or higher and 110° C. or lower. The temperature of the contact-type heating and pressing mechanism (fixing member 3100) and the surface temperature of the recording medium immediately after passing through the contact-type heating and pressing mechanism can both be measured using a radiation thermometer. The radiation thermometer may be installed near the end (terminal end) of the contact-type heating and pressing mechanism. A specific example of the radiation thermometer is a product name "Radiation Thermometer IT-545S" (manufactured by Horiba, Ltd.).

[0065] When the ink contains resin particles, if the temperature of the fixing member 3100 is set to a temperature equal to or higher than the glass transition temperature of the resin particles in the ink, the resin particles soften and are more likely to form a film, improving the scratch resistance of the image. When the ink contains wax particles, it is preferable to set the temperature of the fixing member 3100 lower than the melting point of the wax that constitutes the wax particles. This makes it easier for the wax, which is prevented from melting, to remain on the surface of the image, improving the scratch resistance of the image.

[0066] The nip pressure of the fixing member 3100 and the conveying member 3200, i.e., the pressure applied to the recording medium when it passes through the contact-type heating and pressing mechanism, is preferably from 10 Pa to 1,000 Pa, and more preferably from 10 Pa to 500 Pa. Also, it is particularly preferably from 10 Pa to 400 Pa. The time required for the recording medium to pass through the contact-type heating and pressing mechanism (nip time) is preferably from 0.25 seconds to 5.0 seconds, more preferably from 0.5 seconds to 4.0 seconds, and particularly preferably from 1.0 seconds to 3.0 seconds.

[0067] FIG. 13 is a schematic diagram showing another example of the fixing unit. Here, the difference from the fixing unit shown in FIG. 1 and described above will be described. The fixing unit 3000 shown in FIG. 13 is a contact type heating and pressurizing mechanism including a plurality of fixing rollers 3101 and a plurality of conveying members 3201 arranged opposite to these fixing rollers 3101. An image is fixed on the recording medium 1100 to which a liquid such as ink has been applied by passing between the fixing rollers 3101 and the conveying members 3201. The degree of image fixing on the recording medium can be adjusted by controlling the number of fixing rollers 3101 and the conveying members 3201, the nip time of the recording medium by these, the temperature, the pressure, and the like.

[0068] [Cooling section] The cooling section 4000 is configured to include a cooling member 4100 and a conveying member 4200 (FIG. 1). The cooling section 4000 cools the recording medium 1100, which has been heated to a high temperature after passing through the heating section 2000 and the fixing section 3000. The cooling member 4100 may have any configuration as long as it can cool the recording medium 1100, and methods such as air cooling and water cooling can be used. Among them, blowing unheated gas is preferable in terms of safety and energy efficiency. In addition, if a fan is built in to inject gas onto the recording medium 1100 and a mechanism for blowing air is used, it is easy to improve cooling efficiency. The temperature of the cooling means can be set so that the image on the recording medium has a desired temperature, taking into account the conveying speed and the environmental temperature. Specifically, the temperature of the cooling means (such as air blowing) is preferably 20° C. or higher and 60° C. or lower, and more preferably 25° C. or higher and 50° C. or lower. When cooling by blowing gas, the wind speed is preferably 1 m / s or higher and 100 m / s or lower. By setting such conditions, it is possible to suppress deformation of the recording medium 1100 loaded in the paper discharge unit 6000 described later and image sticking (blocking).

[0069] [Inverted part] When performing double-sided recording, the recording medium 1100 is inverted using the inversion unit 5000 (FIG. 1). The recording medium 1100 with an image recorded on its recording surface (front side) passes through the cooling unit 4000, is branched and transported, and is inverted by the inversion device 5100. The inverted recording medium 1100 is transported to the paper feeder 1400 of the recording unit 1000 with liquid applied to its back side (the side opposite to the recording surface (front side)).

[0070] [Paper output section] After the image is recorded, the recording medium 1100 is stored in a paper discharge section 6000 (FIG. 1). After single-sided or double-sided recording is performed, the recording medium 1100 passes through the cooling section 4000, is transported by a transport member 6100, and is finally stored in a stacked state in a recording medium storage section 6200. Two or more recording medium storage sections 6200 may be provided to store different recorded materials, etc.

[0071] <Maintenance fluid> Next, the maintenance liquid of the present invention that can be used in the ink set, recording method, and recording apparatus described above will be described in detail. This maintenance liquid is used in the ink jet recording method using the ink set described above. The maintenance liquid contains aminosulfonic acid, which is a compound having a sulfo group and an amino group in the molecule.

[0072] (Aminosulfonic acid) The maintenance liquid contains aminosulfonic acid. Aminosulfonic acid is a compound having a sulfo group (-SO3H) and an amino group (-NH2) in the molecule. Examples of aminosulfonic acid include aminomethanesulfonic acid, 2-aminoethanesulfonic acid (also known as taurine), 3-amino-1-propanesulfonic acid, 2-aminobenzenesulfonic acid, and 3-aminobenzenesulfonic acid. One of these may be contained alone or two or more may be contained in combination in the maintenance liquid.

[0073] Among aminosulfonic acids, aminosulfonic acids having a pKa1 of 2.0 or less are preferred. By containing an aminosulfonic acid having a pKa1 of 2.0 or less in the maintenance liquid, the dispersibility of the adhered matter in the maintenance liquid can be increased, and the removability of the adhered matter from the discharge port surface can be increased. Among the specific examples of aminosulfonic acids listed above, 3-amino-1-propanesulfonic acid (pKa1=1.1) and 2-aminoethanesulfonic acid (pKa1=1.5) can be listed as aminosulfonic acids having a pKa1 of 2.0 or less. pKa indicates the ease of dissociation of protons in an acid, and is the negative common logarithm (pKa=-log10Ka) of the acid dissociation constant (Ka). The amount of acid dissociated in the maintenance liquid mainly depends on the pKa of the first-stage dissociation reaction in which hydrogen ions are released from the acid. For this reason, in the case of a compound with multiple pKa's, the pKa of an aminosulfonic acid refers to the pKa (pKa1) of the first dissociation reaction in which a hydrogen ion is released from the acid.

[0074] As the aminosulfonic acid, it is particularly preferable to use 2-aminoethanesulfonic acid (taurine). 2-aminoethanesulfonic acid has a structure in which an amino group and a sulfo group are connected by two carbons (ethylene groups). As a result, the distance between the amino group that acts on the adhered matter and the sulfo group that imparts dispersibility is appropriate, so that the dispersibility of the adhered matter in the maintenance liquid can be increased, and the removability of the adhered matter from the discharge port surface can be further increased.

[0075] The content (mass %) of aminosulfonic acid in the maintenance liquid is preferably 0.1 mass % or more and 1.0 mass % or less, and more preferably 0.1 mass % or more and 0.7 mass % or less, based on the total mass of the maintenance liquid. When the content of aminosulfonic acid in the maintenance liquid is 0.1 mass % or more, it is easy to ensure the amount of aminosulfonic acid that acts on the stuck-on substances, and it is easy to improve the removability of the stuck-on substances from the discharge port surface. On the other hand, when the content of aminosulfonic acid in the maintenance liquid is 1.0 mass % or less, it is difficult for aminosulfonic acid to precipitate when the water in the maintenance liquid remaining on the discharge port surface evaporates, and it is easy to prevent the occurrence of non-discharge due to the precipitate adhering to the discharge port surface.

[0076] (aqueous medium) The maintenance liquid is preferably an aqueous maintenance liquid containing at least water as an aqueous medium. The maintenance liquid may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used. The water content (mass %) in the maintenance liquid is preferably 50.0 mass % or more and 99.0 mass % or less, and more preferably 60.0 mass % or more and 97.0 mass % or less, based on the total mass of the maintenance liquid.

[0077] The maintenance liquid preferably contains a water-soluble organic solvent. The action of the water-soluble organic solvent causes the adhered matter to swell, resulting in some parts being peeled off from the ejection port surface. This allows the maintenance liquid to penetrate between the ejection port surface and the adhered matter, and the maintenance liquid acts on the adhered matter efficiently. As a result, the dispersibility of the adhered matter can be increased, and the ease of removing the adhered matter from the ejection port surface can be increased.

[0078] The content (mass %) of the water-soluble organic solvent in the maintenance liquid is preferably 2.0 mass % or more and 10.0 mass % or less, and more preferably 3.0 mass % or more and 9.0 mass % or less, based on the total mass of the maintenance liquid.

[0079] In addition to removing the solidified matter adhering to the ejection port surface, the maintenance liquid can also be used as a moisturizing liquid when the head is left unattended to prevent non-ejection when the head is left unattended. When recording is not performed temporarily, the recording head is capped and left unattended to prevent the ink from drying and forming a film due to evaporation of moisture from the ejection port. At that time, the maintenance liquid is filled into the cap to moisturize the inside of the recording head, thereby preventing non-ejection when the head is left unattended. In this case, by making the content of the water-soluble organic solvent in the maintenance liquid 2.0% by mass or more, the speed of evaporation of moisture in the maintenance liquid can be suppressed, and the moisturizing effect inside the cap can be easily obtained, and as a result, the occurrence of non-ejection of ink can be easily prevented. On the other hand, by making the content of the water-soluble organic solvent in the maintenance liquid 10.0% by mass or less, the moisture content in the maintenance liquid can be ensured. As a result, while the recording head is capped and left unattended, the humidity inside the cap can be easily kept constant by the moisture in the maintenance liquid and the moisture in the ink inside the ejection port, and as a result, the occurrence of non-ejection of ink can be easily prevented.

[0080] The SP value of the water-soluble organic solvent contained in the maintenance liquid according to the Fedors method [unit: (cal / cm 3 ) 1 / 2 ] is preferably 11.0 or more and 15.0 or less.

[0081] As described above, the maintenance liquid can be used to remove any solidified material adhering to the ejection port surface and as a moisturizing liquid to prevent non-ejection when the cap is left unattended, and can also be used to prevent the accumulation of solidified material due to preliminary ejection inside the cap and to prevent adhesion inside the ink flow path.

[0082] If ink with low dispersibility in the maintenance liquid is continuously pre-ejected into the cap, solidified matter will accumulate inside the cap as the water in the ink evaporates, and when the print head is capped, the deposits may come into contact with the nozzle face of the print head and affect the printed image. To prevent this, the place where the ink is pre-ejected (for example, the cap absorber) is impregnated with maintenance liquid, and the pre-ejected ink diffuses into the maintenance liquid, which has the effect of preventing the accumulation of solidified matter.

[0083] Furthermore, when ink is sucked by cap suction, ink flows into the cap and into the waste ink flow path. If the flow path is left as it is after that, the ink will solidify as the moisture evaporates, blocking the flow path and making it difficult for ink to pass through. To prevent this, the flow path is washed with maintenance liquid after the ink has been sucked, which has the effect of preventing ink from solidifying in the flow path.

[0084] When the SP value of the water-soluble organic solvent in the maintenance liquid is 11.0 or more, when the water in the mixture of the ink and the maintenance liquid evaporates, the SP value of the water-soluble organic solvent is high, so it is easy to suppress the formation of a resin film. This makes it easier to obtain the effect of suppressing the accumulation of solidified matter in the cap and the effect of suppressing solidification in the flow path. On the other hand, when the SP value of the water-soluble organic solvent in the maintenance liquid is 15.0 or less, the effect of swelling solidified matter on the ejection port surface is enhanced, so it is easier to obtain the effect of including the water-soluble organic solvent in the maintenance liquid.

[0085] The SP value (δ) of the water-soluble organic solvent is a value calculated by the Fedors method based on the following formula (A) [unit: (cal / cm 3 ) 1 / 2 ].

[0086] TIFF2025036165000001.tif16170 (In formula (A), ΔEvap represents the molar heat of vaporization (cal / mol) of the water-soluble organic solvent, and V represents the molar volume (cc / mol) of the water-soluble organic solvent at 25°C.)

[0087] As the water-soluble organic solvent that can be contained in the maintenance liquid, any water-soluble organic solvent that is generally used in water-based inks for inkjet printing can be used. For such water-soluble organic solvents, the SP value according to the Fedors method is shown in parentheses in units of (cal / cm 3 ) 1 / 2 When the above is omitted, the following specific examples can be given: The following water-soluble organic solvents can be contained in the maintenance liquid either alone or in combination of two or more.

[0088] Glycerin (16.4), 1-hydroxy-2-pyrrolidone (16.4), 1,3-propanediol (16.1), trimethylolpropane (15.9), 1,4-butanediol (15.0), diethylene glycol (15.0), ethylene glycol (14.8), 1,3-butanediol (14.8), 2-methyl-1,3-propanediol (14.8), 1,2,6-hexanetriol (14.5), urea (14.4), ethyleneurea (14.2), 1,5-pentanediol (14.2), 1-(hydroxymethyl)-2-pyrrolidone ( 14.2), 1,2,7-heptanetriol (13.9), methanol (13.8), triethanolamine (13.7), triethylene glycol (13.6), 1,6-hexanediol (13.5), 1-(2-hydroxyethyl)-2-pyrrolidone (13.5), propylene glycol (13.5), 3-methyl-1,5-pentanediol (13.4), 2-ethylpropane-1,3-diol (13.2), 2-methylpentane-2,4-diol (13.1), tetramethylene sulfoxide (12.9), 1-(3-hydroxypropyl) -2-pyrrolidone (12.9), tetraethylene glycol (12.8), polyethylene glycol with number average molecular weight of 200 (12.8), 1,2-butanediol (12.8), 2-pyrrolidone (12.6), 1-(4-hydroxybutyl)-2-pyrrolidone (12.5), 1,2-pentanediol (12.2), 3-methylsulfolane (12.1), ethylene glycol monomethyl ether (12.0), n-propanol (11.8), 1,2-hexanediol (11.8), isopropanol (11.6), N-methyl-2-pyrrolidone (11. 5), ethylene glycol monoethyl ether (11.5), 1,3-dimethyl-2-imidazolidinone (11.4), n-butanol (11.3), diethylene glycol monomethyl ether (11.2), 2-butanol (11.1), isobutanol (11.1), diethylene glycol monoethyl ether (10.9), triethylene glycol monoethyl ether (10.6), polyethylene glycol with a number average molecular weight of 600 (10.5), diethylene glycol monobutyl ether (10.5), 3-methoxy-3-methylbutanol (10.5), triethylene glycol monobutyl ether (10.3), tetraethylene glycol monobutyl ether (10.2), polyethylene glycol with a number average molecular weight of 1000 (10.1), gamma-butyrolactone (9.9), 3-methoxy-N,N-dimethylpropionamide (9.2), tetraethylene glycol dimethyl ether (8.5), triethylene glycol butyl methyl ether (8.4), ethylene glycol dimethyl ether (7.6).

[0089] (Other Ingredients) In addition to the above components, the maintenance liquid may contain various additives as necessary, such as an antifoaming agent, a surfactant, a pH adjuster, a viscosity adjuster, an antirust agent, an antiseptic, an antifungal agent, an antioxidant, an antireducing agent, etc. The surfactant is preferably at least one selected from the group consisting of silicone-based surfactants and acetylene-based surfactants.

[0090] (Physical properties of maintenance fluid) The pH of the maintenance liquid at 25°C is preferably 7.0 or more and 12.0 or less, more preferably 8.0 or more and 11.0 or less, and even more preferably 8.5 or more and 10.5 or less. By making the pH of the maintenance liquid 7.0 or more, it is possible to obtain stable dispersibility of the fixed matter. On the other hand, by making the pH of the maintenance liquid 12.0 or less, it is easy to suppress corrosion of the members and recording head materials that come into contact with the maintenance liquid, and elution of organic matter due to corrosion. In addition, by making it easy to suppress elution of organic matter, it is easy to suppress the generation of aggregates caused by the eluted organic matter adhering to the ejection port surface and mixing with the ink.

[0091] The dynamic surface tension (mN / m) of the maintenance liquid at 25°C with a life time of 10 ms is preferably 45 mN / m or more. If the dynamic surface tension of the maintenance liquid with a life time of 10 ms is 45 mN / m or more, the maintenance liquid can remain in a certain area on the surface of the fixed object for a while after the maintenance liquid comes into contact with the surface of the fixed object, and the anionic group and the amino group can act efficiently. As a result, the dispersibility of the fixed object can be increased, and the removability of the fixed object from the ejection orifice surface can be increased. The dynamic surface tension of the maintenance liquid with a life time of 10 ms is more preferably 50 mN / m or more, and more preferably 62 mN / m or less.

[0092] The dynamic surface tension of the maintenance liquid is measured by the maximum bubble pressure method. The maximum bubble pressure method is a method in which the maximum pressure required to release bubbles generated at the tip of a probe (thin tube) immersed in the liquid to be measured is measured, and the surface tension of the liquid is calculated from the measured maximum pressure. Specifically, the maximum pressure is measured while continuously generating bubbles at the tip of the probe. The time from when a new bubble surface is generated at the tip of the probe to when the maximum bubble pressure (the point when the radius of curvature of the bubble is equal to the radius of the tip of the probe) is reached is called the "lifetime". In other words, the maximum bubble pressure method is a method for measuring the surface tension of a liquid in a moving state. The dynamic surface tension of the maintenance liquid at 10 milliseconds can be easily adjusted by the type and content of the water-soluble organic solvent and surfactant.

[0093] The viscosity of the maintenance liquid at 25° C. is preferably 0.5 mPa·s or more and 10.0 mPa·s or less.

[0094] <Reaction solution> The recording method of the present invention preferably includes a reaction liquid application step of applying an aqueous reaction liquid containing a reactant that reacts with the aqueous ink to a recording medium. The ink set described above may further include an aqueous reaction liquid in addition to the aqueous ink and the maintenance liquid. Each component used in the reaction liquid will be described in detail below.

[0095] [Reactants] The reaction liquid reacts with the ink when it comes into contact with the ink, and aggregates the components in the ink (components having anionic groups, such as resins, surfactants, and self-dispersing pigments), and contains a reactant. The presence of the reactant can destabilize the state of the components having anionic groups in the ink when the ink and the reactant come into contact with each other on the recording medium, and promote the aggregation of the ink. Examples of the reactant include cationic components such as polyvalent metal ions and cationic resins, and organic acids. The reactant may be used alone or in combination of two or more.

[0096] Examples of polyvalent metal ions constituting polyvalent metal salts include Ca. 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Sr 2+ , B.A. 2+ , and Zn 2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ , and Al 3+ Examples of the polyvalent metal ion include trivalent metal ions such as Cl. One of these polyvalent metal ions can be contained in the reaction solution alone, or two or more of them can be combined. In order to contain the polyvalent metal ion in the reaction solution, a water-soluble polyvalent metal salt (which may be a hydrate) formed by combining a polyvalent metal ion with an anion can be used. Examples of the anion include Cl. - , Br - , I - , ClO - , ClO2 - , ClO3 - , ClO4 - , NO2 - , NO3 - , SO4 2- , CO3 2- , HCO3 - , PO4 3- , HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO- ), CH3COO - , CH3CH(OH)COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2, and CH3SO3 - In the case where a polyvalent metal ion is used as a reactant, the content (mass%) of the polyvalent metal salt in the reaction solution is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction solution. In this specification, when the polyvalent metal salt is a hydrate, the "content (mass%) of the polyvalent metal salt" in the reaction solution means the "content (mass%) of the anhydride of the polyvalent metal salt" excluding water as the hydrate.

[0097] The reaction liquid containing an organic acid has a buffering ability in the acidic range (less than pH 7.0, preferably pH 2.0 to 5.0), and thus efficiently converts the anionic groups of the components present in the ink into an acid form and causes them to aggregate. Examples of the organic acid include monocarboxylic acids and salts thereof, such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and salts and hydrogen salts thereof, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and salts and hydrogen salts thereof, such as citric acid and trimellitic acid; and tetracarboxylic acids and salts and hydrogen salts thereof, such as pyromellitic acid. One of these organic acids can be contained alone or in combination of two or more of them in the reaction liquid. When an organic acid is used as the reactant, the content (mass %) of the organic acid in the reaction liquid is preferably 1.0 mass % or more and 50.0 mass % or less based on the total mass of the reaction liquid.

[0098] Examples of the cationic resin include resins having a structure of primary to tertiary amines and resins having a structure of quaternary ammonium salts. Specific examples include resins having a structure of vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensate. One of these cationic resins can be contained alone or in combination of two or more in the reaction liquid. In order to increase the solubility in the reaction liquid, the cationic resin can be used in combination with an acidic compound or the cationic resin can be subjected to a quaternary treatment. When a cationic resin is used as a reactant, the content (mass%) of the cationic resin in the reaction liquid is preferably 0.1 mass% or more and 10.0 mass% or less based on the total mass of the reaction liquid.

[0099] [Aqueous medium] The reaction liquid is an aqueous reaction liquid containing at least water as an aqueous medium. The aqueous medium used in the reaction liquid can be the same as the aqueous medium that can be contained in the ink described later. The aqueous medium used in the reaction liquid can contain the water-soluble organic solvent that can be contained in the ink described later. The content (mass%) of the water-soluble organic solvent in the reaction liquid is preferably 1.0 mass% or more and 45.0 mass% or less based on the total mass of the reaction liquid. The water-soluble organic solvent preferably contains a specific water-soluble hydrocarbon compound described later. The content (mass%) of the water-soluble hydrocarbon compound in the reaction liquid is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction liquid. In addition, the content (mass%) of water in the reaction liquid is preferably 50.0 mass% or more and 95.0 mass% or less based on the total mass of the reaction liquid.

[0100] [Other ingredients] The reaction liquid may contain various other components as necessary, including the same components as those that can be contained in the ink, which will be described later.

[0101] [Physical properties of reaction solution] The reaction liquid is an aqueous reaction liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the reaction liquid at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the reaction liquid at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the reaction liquid at 25°C is preferably 5.0 or more and 9.5 or less, and more preferably 6.0 or more and 9.0 or less.

[0102] <Ink> The ink set of the present invention includes an ink as well as the maintenance liquid. The recording method uses an ink set including an ink as well as the maintenance liquid. The ink used in this recording method is an inkjet water-based ink that contains a pigment dispersed by the action of anionic groups and resin particles dispersed by the action of anionic groups. In the recording method of the present invention, the water-based ink can be ejected from the ejection port of a liquid application device to record an image on a recording medium. Each component used in the ink will be described in detail below.

[0103] [Colorant] The ink contains a pigment dispersed by the action of an anionic group as a coloring material, and the content (mass %) of the pigment in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

[0104] Specific examples of pigments include inorganic pigments such as carbon black and titanium oxide, and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, dioxazine, etc. The pigments may be used alone or in combination of two or more.

[0105] As the dispersion method of the pigment, a resin-dispersed pigment using a resin as a dispersant, a self-dispersed pigment in which a hydrophilic group is bonded to the pigment particle surface, etc. can be used. In addition, a resin-bonded pigment in which an organic group containing a resin is chemically bonded to the pigment particle surface, and a microcapsule pigment in which the surface of the pigment particle is coated with a resin, etc. can be used. It is also possible to use a combination of pigments with different dispersion methods among these. In particular, it is preferable to use a resin-dispersed pigment in which a resin as a dispersant is physically adsorbed on the pigment particle surface, rather than a resin-bonded pigment or a microcapsule pigment.

[0106] As the resin dispersant for dispersing the pigment in the aqueous medium, it is preferable to use one that can disperse the pigment in the aqueous medium by the action of anionic groups. As the resin dispersant, a resin having an anionic group can be used, and it is preferable to use a resin as described below, especially a water-soluble resin. The content (mass%) of the pigment in the ink is preferably 0.3 times or more and 10.0 times or less in mass ratio to the content (mass%) of the resin dispersant.

[0107] As the self-dispersing pigment, an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group can be used, which is bonded to the particle surface of the pigment directly or via another atomic group (-R-). The anionic group may be either an acid type or a salt type, and when it is a salt type, it may be either a partially dissociated state or a completely dissociated state. When the anionic group is a salt type, examples of the cation that serves as the counter ion include an alkali metal cation, ammonium, and organic ammonium. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms; an arylene group such as a phenylene group or a naphthylene group; a carbonyl group; an imino group; an amide group; a sulfonyl group; an ester group; and an ether group. In addition, it may be a group that is a combination of these groups.

[0108] The ink may contain a dye as a coloring material together with a pigment. It is preferable to use a dye having an anionic group as the dye. Specific examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, and anthrapyridone dyes. The dye may be used alone or in combination of two or more kinds. The coloring material is preferably a pigment, and more preferably a resin-dispersed pigment or a self-dispersed pigment.

[0109] [resin] The ink contains resin particles dispersed by the action of anionic groups. By using an ink containing resin particles, an image with improved abrasion resistance can be recorded. The ink can also contain a water-soluble resin that can be dissolved in an aqueous medium. Hereinafter, the resin particles and the water-soluble resin may be collectively referred to simply as "resin". The resin can be added to the ink (i) to stabilize the dispersion state of the pigment, that is, as a resin dispersant or its auxiliary. Also, the resin can be added to the ink (ii) to improve various properties of the recorded image.

[0110] The content (mass%) of the resin in the ink is preferably 0.1% by mass or more and 20.0% by mass or less, more preferably 0.5% by mass or more and 15.0% by mass or less, based on the total mass of the ink. Examples of the form of the resin include block copolymers, random copolymers, graft copolymers, and combinations thereof. The resin may be used alone or in combination of two or more kinds.

[0111] [Resin Composition] Examples of the resin include acrylic resins, urethane resins, olefin resins, etc. Among them, acrylic resins and urethane resins are preferred, and acrylic resins composed of units derived from (meth)acrylic acid or (meth)acrylate are more preferred.

[0112] The acrylic resin preferably has a hydrophilic unit and a hydrophobic unit as constituent units. Among them, the water-soluble resin preferably has a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one of a monomer having an aromatic ring and a (meth)acrylic acid ester monomer. The monomer having an aromatic ring is more preferably at least one of styrene and α-methylstyrene. These resins are easily interacted with pigments, and therefore can be suitably used as a resin dispersant for dispersing pigments. In addition, the resin particles are particularly preferably formed from an acrylic resin. Among them, in order to prevent the hydrophobicity of the resin particles from becoming too high, those formed from a resin that does not have a unit having a naphthalene structure are preferred.

[0113] The hydrophilic unit is a unit having a hydrophilic group such as an anionic group. The hydrophilic unit can be formed, for example, by polymerizing a hydrophilic monomer having a hydrophilic group. Specific examples of the hydrophilic monomer having a hydrophilic group include acidic monomers having a carboxylic acid group such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid, and anionic monomers such as anhydrides and salts of these acidic monomers. Examples of cations constituting the salts of acidic monomers include ions of lithium, sodium, potassium, ammonium, and organic ammonium. One or more types of hydrophilic monomers can be used for the resin.

[0114] The hydrophobic unit is a unit that does not have a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer that does not have a hydrophilic group such as an anionic group. Specific examples of the hydrophobic monomer include monomers having an aromatic ring such as styrene, α-methylstyrene, and benzyl (meth)acrylate; and (meth)acrylic acid ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. One or more types of hydrophobic monomers can be used in the resin.

[0115] The urethane resin can be obtained by reacting, for example, polyisocyanate with a polyol. In addition, a chain extender may be further reacted with the urethane resin. Examples of the olefin resin include polyethylene and polypropylene.

[0116] [Resin properties] In this specification, the term "resin particles" means that when the resin is neutralized with an alkali equivalent to the acid value, it is present in an aqueous medium in a state in which it forms particles whose particle diameter can be measured by dynamic light scattering. In addition, in this specification, the term "a resin is water-soluble" means that when the resin is neutralized with an alkali equivalent to the acid value, it is present in an aqueous medium in a state in which it does not form particles whose particle diameter can be measured by dynamic light scattering. Whether or not it is a resin particle can be determined according to the following method. First, a liquid (resin solid content: 10 mass%) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to the acid value is prepared. Next, the prepared liquid is diluted 10 times (volume basis) with pure water to prepare a sample solution. Then, when the particle diameter of the resin in the sample solution is measured by dynamic light scattering, if particles having a particle diameter are measured, the resin can be determined to be a resin particle. In addition, if particles having a particle diameter are not measured, the resin can be determined to be water-soluble. The measurement conditions at this time can be, for example, SetZero: 30 seconds, number of measurements: 3 times, and measurement time: 180 seconds. As the particle size distribution measuring device, a particle size analyzer using a dynamic light scattering method (for example, the product name "UPA-EX150" manufactured by Nikkiso) can be used. Of course, the particle size distribution measuring device and the measurement conditions used are not limited to those described above.

[0117] The acid value of the water-soluble resin is preferably 100 mgKOH / g or more and 250 mgKOH / g or less, and the weight average molecular weight of the water-soluble resin is preferably 3,000 or more and 15,000 or less.

[0118] The acid value of the resin constituting the resin particles is preferably 5 mgKOH / g or more and 100 mgKOH / g or less. The weight average molecular weight of the resin constituting the resin particles is preferably 1,000 or more and 3,000,000 or less, and more preferably 100,000 or more and 3,000,000 or less. The volume-based cumulative 50% particle diameter (D 50) is preferably 50 nm or more and 500 nm or less. The volume-based cumulative 50% particle diameter of the resin particles is the diameter of the particles that is 50% of the total volume of the measured particles when integrated from the small particle diameter side in a particle diameter integration curve. The volume-based cumulative 50% particle diameter of the resin particles can be measured using the dynamic light scattering particle size analyzer and measurement conditions described above. The glass transition temperature of the resin particles is preferably 40° C. or more and 120° C. or less, and more preferably 50° C. or more and 100° C. or less. The glass transition temperature (° C.) of the resin particles can be measured using a differential scanning calorimeter (DSC). The resin particles do not need to contain a coloring material.

[0119] [Wax particles] The ink may contain particles formed of wax (wax particles). By using an ink containing wax particles, an image with improved abrasion resistance can be recorded. In this specification, the wax may be a composition containing components other than wax, or the wax itself. The wax particles may be dispersed by a dispersant such as a surfactant or a resin. The wax may be used alone or in combination of two or more kinds. The content (mass %) of the wax particles in the ink is preferably 0.1 mass % or more and 10.0 mass % or less, and more preferably 1.0 mass % or more and 5.0 mass % or less, based on the total mass of the ink.

[0120] In the narrow sense, wax is an ester of a water-insoluble higher monohydric or dihydric alcohol and a fatty acid, and includes animal waxes and vegetable waxes, but does not include oils and fats. In the broad sense, wax includes high melting point fats, mineral waxes, petroleum waxes, and blends and modified products of various waxes. In the present invention, any wax in the broad sense can be used without particular restrictions. Wax in the broad sense can be classified into natural waxes, synthetic waxes, blends thereof (blended waxes), and modified products thereof (modified waxes).

[0121] Examples of natural waxes include animal waxes such as beeswax, spermaceti, and wool wax (lanolin); vegetable waxes such as wood wax, carnauba wax, sugarcane wax, palm wax, candelilla wax, and rice wax; mineral waxes such as montan wax; and petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum. Examples of synthetic waxes include hydrocarbon waxes such as Fischer-Tropsch wax and polyolefin wax (e.g., polyethylene wax and polypropylene wax). The blended wax is a mixture of the above-mentioned various waxes. The modified wax is a wax obtained by subjecting the above-mentioned various waxes to a modification treatment such as oxidation, hydrogenation, alcohol modification, acrylic modification, and urethane modification. One of the above waxes may be used alone, or two or more may be used in combination. The wax is preferably at least one selected from the group consisting of microcrystalline wax, Fischer-Tropsch wax, polyolefin wax, paraffin wax, and modified or blended products thereof. Among them, a blend of multiple types of wax is more preferable, and a blend of a petroleum wax and a synthetic wax is particularly preferable.

[0122] The wax is preferably solid at room temperature (25°C). The melting point (°C) of the wax is preferably 40°C or higher and 120°C or lower, and more preferably 50°C or higher and 100°C or lower. The melting point of the wax can be measured in accordance with the test method described in 5.3.1 (melting point test method) of JIS K2235:1991 (petroleum wax). In the case of microcrystalline wax, petrolatum, and a mixture of multiple types of wax, the test method described in 5.3.2 can be used to measure more accurately. The melting point of the wax is easily affected by characteristics such as molecular weight (the higher the molecular weight, the higher the melting point), molecular structure (the higher the melting point if the chain is straight, and the lower the melting point if there is branching), crystallinity (the higher the crystallinity, the higher the melting point), and density (the higher the crystallinity, the higher the melting point). Therefore, by controlling these characteristics, it is possible to obtain a wax having a desired melting point. The melting point of the wax in the ink can be measured in accordance with the above test method, for example, after the ink is subjected to ultracentrifugation, the wax separated is washed and dried.

[0123] [Aqueous medium] The ink is an aqueous ink containing at least water as an aqueous medium. The ink may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used. The content (mass%) of water in the aqueous ink is preferably 50.0 mass% or more and 95.0 mass% or less based on the total mass of the ink. In addition, the content (mass%) of the water-soluble organic solvent in the aqueous ink is preferably 2.0 mass% or more and 40.0 mass% or less based on the total mass of the ink. As the water-soluble organic solvent, any of those usable for inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing solvents, and sulfur-containing solvents, can be used. The water-soluble organic solvent may be used alone or in combination of two or more.

[0124] [Water-soluble hydrocarbon compounds] The water-soluble organic solvent contained in the ink preferably contains a specific water-soluble hydrocarbon compound. This water-soluble hydrocarbon compound is a compound having a hydrocarbon chain having three or more carbon atoms substituted with two or more hydrophilic groups selected from the group consisting of hydroxyl groups, amino groups, and anionic groups. However, the hydrocarbon chain may be interrupted by a sulfonyl group or an ether group. When the hydrocarbon chain has three or four carbon atoms, the hydrophilic group contains an anionic group, or the hydrocarbon chain is interrupted by a sulfonyl group.

[0125] In the present invention, a hydrocarbon compound that is dissolved in water at 25°C at the content of the compound in the ink is considered to be "water-soluble". In other words, the solubility in water at 25°C is greater than the content in the ink. The fact that the hydrocarbon chain is interrupted by a sulfonyl group or an ether group means that a sulfonyl group (-S(=O)2-) or an ether group (-O-) is present in the middle of the hydrocarbon chain. Water-soluble hydrocarbon compounds have hydrogen-bonding groups such as hydroxyl groups, amino groups, anionic groups, sulfonyl groups, and ether groups. Therefore, by using an ink containing this hydrocarbon compound, cockling and curling of a recording medium on which an image is recorded can be suppressed. General hydrocarbon compounds having a hydrocarbon chain with a relatively small number of carbon atoms (3 or 4) tend to have a small molecular weight and a low vapor pressure. However, since the above water-soluble hydrocarbon compounds have anionic groups of hydrogen bonds or the hydrocarbon chain is interrupted by a sulfonyl group, they are difficult to evaporate due to inter- or intra-molecular interactions, and remain between fibers to suppress cockling and curling. The content (mass %) of the water-soluble hydrocarbon compound in the ink is preferably 1.0 mass % or more and 20.0 mass % or less based on the total mass of the ink.

[0126] The number of carbon atoms in the hydrocarbon chain constituting the water-soluble hydrocarbon compound is preferably from 3 to 50, and more preferably from 3 to 10. Examples of the anionic group include a sulfonic acid group and a carboxylic acid group. Specific examples of water-soluble hydrocarbon compounds include alkanediols such as 1,5-pentanediol and 1,6-hexanediol; amino acids such as alanine, β-alanine, trimethylglycine, amidosulfuric acid (also known as sulfamic acid), aminomethanesulfonic acid, taurine (also known as 2-aminoethanesulfonic acid), carbamic acid, glycine, aspartic acid, glutamic acid, sulfanilic acid, or salts of the above-mentioned acids, phenylalanine, leucine, isoleucine, threonine, tryptophan, valine, methionine, lysine, and arginine; sulfonyl compounds such as bis(2-hydroxyethyl)sulfone; alkylene glycols such as triethylene glycol, tetraethylene glycol, tripropylene glycol, and polyethylene glycols having a number average molecular weight of about 200 to 1,000; and sugars such as sorbitol, D-sorbitol, xylitol, trehalose, fructose, and D(+)-xylose. The water-soluble hydrocarbon compounds may be used alone or in combination of two or more.

[0127] [Other ingredients] The ink may contain various other components as necessary. Examples of other components include various additives such as defoamers, surfactants, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors. However, it is preferable that the ink does not contain a reactant to be contained in the reaction liquid.

[0128] [Ink properties] The ink is a water-based ink applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the ink at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the ink at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the ink at 25°C is preferably 7.0 or more and 9.5 or less, and more preferably 8.0 or more and 9.5 or less. EXAMPLES

[0129] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples without departing from the gist of the invention. "Parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified.

[0130] <Preparation of reaction solution> The components shown below were mixed and thoroughly stirred, and then pressure filtered through a cellulose acetate filter (manufactured by Advantec Toyo) with a pore size of 3.0 μm to prepare a reaction liquid. Magnesium sulfate heptahydrate: 15.0% Glycerin: 8.0% Acetylenol E100 (surfactant made by Kawaken Fine Chemicals): 1.0% Ion-exchanged water: 76.0%

[0131] <Preparation of pigment dispersion> (Pigment dispersion 1) A styrene-ethyl acrylate-acrylic acid copolymer (resin 1) with an acid value of 150 mgKOH / g and a weight average molecular weight of 8,000 was prepared. 20.0 parts of resin 1 were neutralized with potassium hydroxide in an amount equimolar to the acid value, and an appropriate amount of pure water was added to prepare an aqueous solution of resin 1 with a resin (solid content) content of 20.0%. A mixture was obtained by mixing 10.0 parts of pigment (CI Pigment Blue 15:3), 15.0 parts of the aqueous solution of resin 1, and 75.0 parts of pure water. The obtained mixture and 200 parts of zirconia beads with a diameter of 0.3 mm were placed in a batch-type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. After removing coarse particles by centrifugation, the mixture was pressure-filtered with a cellulose acetate filter with a pore size of 3.0 μm (manufactured by Advantec Toyo). In this way, pigment dispersion 1 was prepared, which contained a pigment dispersed by the action of the anionic groups of the resin dispersant, with the pigment content being 10.0% and the resin dispersant (resin 1) content being 3.0%.

[0132] (Pigment dispersion 2) Except for changing the pigment to CI Pigment Red 122, pigment dispersion 2 was prepared in the same manner as pigment dispersion 1 described above. The pigment content was 10.0% due to the action of the anionic groups of the resin dispersant, and the resin dispersant (resin 1) content was 3.0%.

[0133] (Pigment dispersion 3) Except for changing the pigment to CI Pigment Yellow 74, the same procedure as for Pigment Dispersion 1 described above was used to prepare Pigment Dispersion 3, which had a pigment content of 10.0% dispersed by the action of the anionic groups of the resin dispersant and a resin dispersant (Resin 1) content of 3.0%.

[0134] (Pigment Dispersion 4) Except for changing the pigment to carbon black, pigment dispersion 4 was prepared in the same manner as pigment dispersion 1 described above. The pigment content was 10.0% due to the action of the anionic groups of the resin dispersant, and the resin dispersant (resin 1) content was 3.0%.

[0135] (Pigment Dispersion 5) Pigment dispersion 5 was prepared in the same manner as pigment dispersion 1, except that resin 1 was changed to a styrene-2-hydroxyethyl acrylate copolymer (resin 2), which is a resin not having an anionic group. The pigment content of pigment dispersion 5 was 10.0%, and the resin dispersant (resin 2) content was 3.0%.

[0136] <Preparation of resin particles> (Resin particles 1) A solution was prepared by mixing 0.2 parts of potassium persulfate and 74.0 parts of ion-exchanged water in a four-neck flask equipped with a stirrer, a reflux condenser, and a nitrogen gas inlet tube. An emulsion was also prepared by mixing 24.0 parts of ethyl methacrylate, 1.5 parts of methacrylic acid, and 0.3 parts of a reactive surfactant (trade name "Aqualon KH-05", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). The emulsion was dropped into the solution in the four-neck flask over 1 hour under a nitrogen atmosphere, polymerized while stirring at 80°C, and then stirred for another 2 hours. After cooling to 25°C, an aqueous solution containing ion-exchanged water and potassium hydroxide equimolar to the acid value of the resin particles was added to obtain an aqueous dispersion of resin particles 1 having an anionic group-containing resin particle (solid content) content of 25.0%.

[0137] (Resin particles 2) In a four-neck flask equipped with a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 81.8 parts of ion-exchanged water and 0.2 parts of potassium persulfate were mixed. In addition, 16.1 parts of ethyl methacrylate, 1.6 parts of methoxypolyethylene glycol methacrylate, and 0.3 parts of a reactive surfactant (trade name "Aqualon KH-05", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were mixed to prepare an emulsion. As the methoxypolyethylene glycol methacrylate, "Blenmar PME1000" (manufactured by NOF Corp., the number of moles of ethylene oxide groups added is about 23) was used. Under a nitrogen atmosphere, the prepared emulsion was dropped into the four-neck flask over 1 hour, and a polymerization reaction was carried out for 2 hours while stirring at 80°C. After cooling to 25°C, ion-exchanged water and an aqueous solution containing potassium hydroxide equimolar to the acid value of the resin particles were added to prepare an aqueous dispersion of resin particles 2 in which the content of resin particles (solid content) without anionic groups is 25.0%.

[0138] <Ink Preparation> The components (unit: %) shown in Table 1 were mixed and thoroughly stirred, and then pressure filtered through a cellulose acetate filter (manufactured by Advantec Toyo) with a pore size of 3.0 μm to prepare each ink. "AQUACER515" is the product name of a wax emulsion manufactured by BYK-Chemie, and the wax particle content is 35% by mass. "Acetylenol E100" is the product name of a surfactant manufactured by Kawaken Fine Chemicals.

[0139] TIFF2025036165000002.tif93170

[0140] <Preparation of maintenance liquid> The components (unit: %) shown in Table 2 (Tables 2-1 to 2-4) were mixed and thoroughly stirred, and then pressure filtered using a cellulose acetate filter (manufactured by Advantec Toyo) with a pore size of 3.0 μm to prepare each maintenance liquid. "BYK3420" is the trade name of a silicone surfactant manufactured by BYK-Chemie. The dynamic surface tension of each maintenance liquid was measured at a life time of 10 milliseconds using a dynamic surface tensiometer (trade name "BUBBLE PRESSURE TENSIOMETER BP-100", manufactured by KRUSS) using the maximum bubble pressure method under conditions of 25°C.

[0141] TIFF2025036165000003.tif132170

[0142] TIFF2025036165000004.tif131170

[0143] TIFF2025036165000005.tif131170

[0144] TIFF2025036165000006.tif131170

[0145] <Evaluation> An inkjet recording apparatus 100 having the configuration shown in FIG. 1 was used to record an image on a recording medium in accordance with the evaluation conditions shown on the left side of Table 3. The reaction liquid application device 1201 of the inkjet recording apparatus 100 was filled with the above-mentioned reaction liquid. Furthermore, the ink application device 1202 and the maintenance liquid pack 101 (see FIG. 7) of the inkjet recording apparatus 100 were filled with the ink and maintenance liquid having the numbers shown on the left side of Table 3, respectively. The reaction liquid was applied to the recording medium by the inkjet method before application of the ink. Furthermore, the ink was also applied to the recording medium by the inkjet method. The amount of reaction liquid applied to the recording medium was set to 2 g / m. 2 , the amount of ink applied was 8 g / m 2 A solid image measuring 1.5 cm x 13 cm was recorded on a recording medium (product name "OK Topcoat+", manufactured by Oji Paper Co., Ltd.). In the heating section 2000 preceding the fixing section 3000 of the inkjet recording device 100, the temperature of the hot air and the conveying speed of the recording medium were adjusted so that hot air at 80°C was applied to the recording medium for 2 seconds. In the fixing section 3000, the pressure applied to the recording medium by the contact-type heating and pressurizing mechanism (fixing pressure (Pa)) was controlled by adjusting the pressure-adjusting spring pressure, and the image was fixed on the recording medium at a nip pressure of 20 Pa, a nip time of 2 seconds, and a heating temperature of 85°C.

[0146] The recorded images were evaluated as follows. In this example, in the evaluation criteria for each item below, "A" and "B" were considered acceptable levels, and "C" was considered unacceptable. The evaluation results are shown on the right side of Table 3.

[0147] (Abrasion resistance) The recorded image was left for 24 hours in an environment with a temperature of 25°C and a relative humidity of 55%, and then rubbed 10 times with a load of 500g using a Gakushin-type abrasion resistance tester (product name "AB-301", manufactured by Tester Sangyo). A recording medium of the same type as the recording medium on which the image was recorded was attached to the friction element as a recording medium for evaluation. The surfaces of the image and the recording medium for evaluation after rubbing were visually observed, and the abrasion resistance of the image was evaluated according to the following evaluation criteria. A: The image was fixed on the recording medium, the white background of the recording medium was not visible, and there was no dirt on the recording medium for evaluation. B: The image was fixed on the recording medium, the white background of the recording medium was no longer visible, and the evaluation recording medium was stained. C: The image was peeled off from the recording medium, revealing the white background of the recording medium.

[0148] (Removability of Adherent Matter from the Discharge Nozzle Surface of a Liquid Applicator) After spraying ink in mist form using a nebulizer onto the ejection port surface of the liquid applicator, the liquid applicator was placed in a 46°C oven and left there for 30 minutes, after which cleaning was performed to remove the ink that had adhered to the ejection port surface using any of the following cleaning conditions 1 to 4. Thereafter, the ejection port surface of the liquid applicator was observed, and the ability to remove the adhered matter from the ejection port surface was evaluated according to the following evaluation criteria. A: Sticking was observed in less than 5% of all outlets. B: Adherence was observed in more than 5% but less than 10% of all outlets. C: Adherence was observed in more than 10% of all outlets.

[0149] [Cleaning condition 1] (Maintenance liquid dispenser, wiper, ink suction) 0.4 g of maintenance liquid was applied to the ejection element substrate including the ejection orifice surface of the liquid applying device by the maintenance liquid applying device. Next, the ejection orifice surface of the liquid applying device was wiped with a wiper blade of the liquid removing device (scanning speed 80 mm / s), and then ink was sucked by a negative pressure applying device (negative pressure -40 kPa or less, scanning speed 5.6 mm / s) to clean the ejection orifice surface.

[0150] [Cleaning condition 2] (No maintenance liquid dispenser, with wiper, with ink suction) 0.4 g of maintenance liquid was applied to the wiper blade of the liquid removal device. At the same time that the maintenance liquid was applied to the discharge element substrate including the discharge port surface of the liquid application device with the wiper blade, the discharge port surface was wiped with the wiper blade (scanning speed 80 mm / s). After that, ink was sucked with a negative pressure application device (negative pressure -40 kPa or less, scanning speed 5.6 mm / s) to clean the discharge port surface.

[0151] [Cleaning condition 3] (Maintenance liquid dispenser included, wiper included, no ink suction) 0.4 g of the maintenance liquid was applied to the ejection element substrate including the ejection orifice surface of the liquid applying device by the maintenance liquid applying device. Next, the ejection orifice surface of the liquid applying device was wiped with a wiper blade of the liquid removing device (scanning speed: 80 mm / s) to clean the ejection orifice surface.

[0152] [Cleaning condition 4] (Maintenance liquid dispenser included, no wiper, ink suction included) The maintenance liquid was applied to the ejection element substrate including the ejection port surface of the liquid applying device by 0.4 g of the maintenance liquid. After that, the ejection port surface was cleaned by sucking the ink with a negative pressure applying device (negative pressure of -40 kPa or less, scanning speed of 5.6 mm / s).

[0153] (Recovery after leaving the cap on) The ink applicator 1202 was filled with ink, and using the inkjet recording apparatus 100 having the configuration shown in Fig. 1, it was confirmed that ink was being ejected from all of the ejection ports of the ink applicator 1202 by using a pattern that could confirm the presence or absence of ejection from all of the ejection ports. The ink applicator filled with ink was capped using a cap with 20 g of maintenance liquid impregnated in the cap absorber, and left for two weeks in an environment with a temperature of 30°C and a relative humidity of 10%. After two weeks, the ink applicator was used to circulate ink inside the ink applicator as a recovery operation, and then a pattern that could confirm the ejection state of all the ejection ports was recorded, and the recovery after leaving the cap alone was evaluated according to the evaluation criteria shown below. A: The number of non-discharges was less than 5% of all discharge ports. B: The number of non-discharge ports was between 5% and 10% of all discharge ports. C: The number of non-discharge nozzles was 10% or more of all nozzles.

[0154] (Pre-ejection deposition) The cap absorbent was impregnated with 20 g of maintenance liquid, and 30 shots of ink were ejected from all ejection ports into the cap using the inkjet recording apparatus 100 configured as shown in Fig. 1, followed by a 5-minute pause, which was repeated 100 times. After that, the state of ink accumulation on the cap absorbent was observed, and preliminary ejection accumulation was evaluated according to the following evaluation criteria. A: No ink buildup was observed. B: Ink accumulation was observed on the cap absorber, but even when the ink applicator was capped, there was no adhesion to the ejection port surface of the ink applicator. C: Ink was deposited on the cap absorber, and when the ink applicator was capped, the deposit adhered to the ejection port surface of the ink applicator.

[0155] (Stuck inside the tube) After 50 g of ink was passed through the tube, 50 g of maintenance liquid was passed through it. After leaving this tube in an open state in an environment of a temperature of 30°C and a relative humidity of 10% for 5 days, 50 g of ink was passed through it and adhesion inside the tube was evaluated according to the following criteria. A: There was no blockage in the flow path, and the ink was able to pass through. B: There was a blockage in the flow path, but ink was able to pass through. C: Ink could not pass through due to a blockage in the flow path.

[0156] TIFF2025036165000007.tif240170

Claims

1. An ink set including a water-based ink and a maintenance liquid used together with the water-based ink, the aqueous ink contains a pigment dispersed by the action of an anionic group and a resin particle having an anionic group; The ink set, wherein the maintenance liquid contains aminosulfonic acid.

2. 2. The ink set according to claim 1, wherein the aminosulfonic acid has a pKa1 of 2.0 or less.

3. 2. The ink set according to claim 1, wherein the aminosulfonic acid is 2-aminoethanesulfonic acid.

4. 2. The ink set according to claim 1, wherein a content (% by mass) of the aminosulfonic acid in the maintenance liquid is 0.1% by mass or more and 1.0% by mass or less based on the total mass of the maintenance liquid.

5. 2. The ink set according to claim 1, wherein the maintenance liquid has a pH value at 25° C. of 7.0 or more and 12.0 or less.

6. 2. The ink set according to claim 1, wherein the maintenance liquid has a dynamic surface tension of 45 mN / m or more at 25[deg.] C. and a life time of 10 ms.

7. The ink set according to claim 1 , wherein the maintenance liquid contains a water-soluble organic solvent.

8. 8. The ink set according to claim 7, wherein the content (mass %) of the water-soluble organic solvent in the maintenance liquid is 2.0 mass % or more and 10.0 mass % or less based on the total mass of the maintenance liquid.

9. The SP value of the water-soluble organic solvent according to the Fedors method [unit: (cal / cm ３ ) １／２ 8. The ink set according to claim 7, wherein the ratio of the total color density to the total color density is 11.0 or more and 15.0 or less.

10. The ink set according to claim 1 , wherein the water-based ink contains wax particles.

11. An inkjet recording method using an ink set including a water-based ink and a maintenance liquid used together with the water-based ink, comprising: the aqueous ink contains a pigment dispersed by the action of an anionic group and a resin particle having an anionic group; The ink-jet recording method, wherein the maintenance liquid contains an aminosulfonic acid.

12. A step of discharging the water-based ink from a discharge port of a liquid application device to record an image on a recording medium; applying the maintenance liquid to a discharge port surface of the liquid application device, the discharge port surface having the discharge port; and cleaning the ejection port surface of the liquid application device; Including, The inkjet recording method according to claim 11, further comprising the step of cleaning the ejection port surface after the step of applying the maintenance liquid to the ejection port surface.

13. The inkjet recording method according to claim 12, wherein in the step of cleaning the ejection port surface of the liquid application device, the ejection port surface is cleaned by a wiper blade and by applying negative pressure.

14. An inkjet recording apparatus including an ink set containing a water-based ink and a maintenance liquid used together with the water-based ink, the aqueous ink contains a pigment dispersed by the action of an anionic group and a resin particle having an anionic group; The inkjet recording apparatus according to claim 1, wherein the maintenance liquid contains aminosulfonic acid.

15. A maintenance liquid for use in an inkjet recording method using an ink set including a water-based ink and a maintenance liquid for use together with the water-based ink, comprising: the aqueous ink contains a pigment dispersed by the action of an anionic group and a resin particle having an anionic group; The maintenance liquid comprises an aminosulfonic acid.

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