Inkjet recording method, inkjet recording device, and set of aqueous ink and aqueous reaction liquid

Abstract

To provide an inkjet recording method which suppresses burial of ink into an image when a plurality of ink is imparted to a non-absorbable recording medium in a superposed manner, and enables recording of an image excellent in adhesion.SOLUTION: An inkjet recording method discharges first ink, second ink, a first reaction liquid and a second reaction liquid from a recording head, and records an image on a recording medium. The inkjet recording method includes a first reaction liquid application step, a first ink application step, a second reaction liquid application step, and a second ink application step, in this order. Viscosity of a mixed liquid 1-1 prepared by mixing the first reaction liquid and the first ink in a mass ratio of 7:100 is higher than viscosity of a mixed liquid 2-1 prepared by mixing the second reaction liquid and the first ink in the mass ratio of 7:100, and viscosity of a mixed liquid 1-2 prepared by mixing the first reaction liquid and the second ink in the mass ratio of 7:100 is higher than viscosity of a mixed liquid 2-2 prepared by mixing the second reaction liquid and the second ink in the mass ratio of 7:100.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In recent years, inkjet recording methods have been increasingly used in the field of sign and display, such as printing posters and large-format advertisements. In this field, inkjet recording devices are characterized by a larger recording area than home inkjet recording devices. In addition, since images need to be eye-catching, inks that can record images with high color development are required.

[0003] In the sign and display field, non-absorbent recording media, whose surfaces are made of polyvinyl chloride (PVC) or polyethylene terephthalate (PET), and whose surfaces have almost no ink absorption, are often used. For this reason, it is necessary to suppress bleeding of images on non-absorbent recording media. Hereinafter, recording media whose surfaces have almost no ink absorption will also be referred to as "non-absorbent recording media." In the inkjet recording method for recording on non-absorbent recording media, it is important to suppress bleeding by preventing ink dots from being repelled by the recording medium. To achieve this, it is necessary to rapidly thicken the ink after it is applied to the recording medium and fix it to the recording medium.

[0004] As a method for recording on a non-absorbent recording medium, a recording method using a solvent-based ink containing an organic solvent as a main component or a curable ink containing a polymerizable monomer is known. However, in recent years, from the viewpoint of environmental load, odor, etc., there is an increasing need for a recording method that can record on a non-absorbent recording medium using a water-based ink.

[0005] Methods of recording on non-absorbent recording media using aqueous ink include a method of evaporating the water content of the ink on the surface of the non-absorbent recording media, and a method of using a reaction liquid that aggregates the ink components. The former is advantageous in terms of running costs because there is no need to provide a means for applying the reaction liquid, but it is necessary to slow down the recording speed, which reduces productivity. For this reason, a method using a reaction liquid has been considered (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-147405 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors recorded on a non-absorbent recording medium using the first reaction liquid, the second reaction liquid, the first ink, and the second ink described in Patent Document 1, and evaluated various characteristics. As a result, although a certain degree of image quality was obtained, it was found that when the inks were applied in layers, the ink applied later was buried in the ink layer that was applied earlier to the recording medium. It was also found that the adhesion of the image (recording medium and ink, ink and ink) was insufficient. When the inks were applied in layers, the phenomenon that the ink applied later was buried in the ink layer that was applied earlier to the recording medium is a phenomenon that can usually occur. However, as a result of the ink being buried in the ink layer, it was found that the image looked different and the intended image could not be obtained. In this specification, "an image in which the ink is prevented from being buried in the image" means an image in which the ink applied later is prevented from mixing with the ink applied earlier, causing a decrease in image quality such as color development.

[0008] Therefore, an object of the present invention is to provide an inkjet recording method that can prevent ink from being buried in an image when a plurality of inks are applied in layers to a non-absorbent recording medium, and can record an image with excellent adhesion. Another object of the present invention is to provide an inkjet recording apparatus and a set of an aqueous ink and an aqueous reaction liquid used in the inkjet recording method. [Means for solving the problem]

[0009] That is, according to the present invention, there is provided an inkjet recording method for ejecting a first ink, a second ink, a first reaction liquid, and a second reaction liquid from a recording head to record an image on a recording medium in which the first ink, the second ink, the first reaction liquid, and the second reaction liquid overlap in at least a partial area, the method comprising: a first reaction liquid applying step of applying the first reaction liquid to the recording medium; a first ink applying step of applying the first ink to an area to which the first reaction liquid is to be applied; a second reaction liquid applying step of applying the second reaction liquid to the recording medium; and a second ink applying step of applying the second ink to an area to which the second reaction liquid is to be applied, in this order; the first ink is an aqueous ink containing a pigment, and the second ink is an ink selected from the group consisting of pigments and resin particles. a water-based ink containing at least one kind of particulate matter that reacts with the ink, the first reaction liquid and the second reaction liquid each being an aqueous reaction liquid containing a reactant that reacts with the ink, the first reaction liquid containing a water-soluble cationic resin, a viscosity of a mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink at a ratio of 7:100 (mass ratio) is higher than a viscosity of a mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink at a ratio of 7:100 (mass ratio), and a viscosity of a mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink at a ratio of 7:100 (mass ratio) is higher than a viscosity of a mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink at a ratio of 7:100 (mass ratio), and 1 / 2 Water absorption up to 10mL / m 2 There is provided an ink jet recording method characterized in that: Effect of the Invention

[0010] According to the present invention, it is possible to provide an inkjet recording method capable of suppressing ink from being buried in an image when a plurality of inks are applied in layers to a non-absorbent recording medium and capable of recording an image having excellent adhesion. Also, according to the present invention, it is possible to provide an inkjet recording apparatus used in the inkjet recording method, and a set of an aqueous ink and an aqueous reaction liquid. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view illustrating an embodiment of an inkjet recording apparatus of the present invention. [Diagram 2] 1 is a side view diagrammatically illustrating an embodiment of an inkjet recording apparatus of the present invention. [Diagram 3] FIG. 1 is a schematic diagram illustrating an embodiment of an inkjet recording apparatus of the present invention. [Figure 4] FIG. 2 is a perspective view showing an example of a liquid application device. [Diagram 5] FIG. 2 is a cross-sectional perspective view showing an example of a discharge element substrate. [Figure 6] FIG. 2 is a schematic diagram showing an example of a liquid supply system. [Figure 7] FIG. 13 is a schematic diagram showing another example of the heating unit. [Figure 8] FIG. 11 is a schematic diagram showing another example of the fixing unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] The present inventors first investigated the reason why the ink was buried and the fixability of the image was reduced in the inkjet recording method using two kinds of reaction liquids and two kinds of inks described in Patent Document 1. In order to suppress the ink from being buried, it is necessary for the ink (first ink) applied first to quickly aggregate and form a first ink layer. Therefore, it is necessary for the reaction liquid (first reaction liquid) applied together with the first ink to be one that quickly causes the ink to aggregate (highly reactive). In addition, if the second reaction liquid applied together with the second ink is one that is as highly reactive as the first reaction liquid, it becomes difficult for it to follow the first ink layer. As a result, it is considered that adhesion cannot be obtained between the first ink layer and the second ink layer, and peeling of the image occurs. Therefore, it was considered that the embedding of the ink in the image and the adhesion of the image would be improved by increasing the reactivity of the first reaction liquid and making the reactivity of the second reaction liquid lower than that of the first reaction liquid. However, it was found that the adhesion of the image was still not obtained even with the above configuration.

[0014] As a result of the study, the present inventors considered the reason why the image adhesion was not obtained as follows. When the reactivity of the first reaction liquid used together with the first ink is increased, unevenness is likely to occur on the surface of the first ink layer. It is considered that the occurrence of unevenness occurs not only on the surface in contact with the second ink but also on the surface in contact with the recording medium, which reduces the ability to follow the recording medium. As a result, the image adhesion becomes insufficient. In light of this situation, the present inventors further studied and found that by adding a water-soluble cationic resin to the first reaction liquid, the ink can be embedded in the image and the image adhesion can be improved.

[0015] That is, the inkjet recording method of the present inventor has the following features. First, the first ink is an aqueous ink containing a pigment. The second ink is an aqueous ink containing at least one particulate material selected from the group consisting of pigments and resin particles. The first reaction liquid and the second reaction liquid are each an aqueous reaction liquid containing a reactant that reacts with the ink, and the reactant of the first reaction liquid contains a water-soluble cationic resin. The viscosity of the mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink at a ratio of 7:100 (mass ratio) is higher than the viscosity of the mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink at a ratio of 7:100 (mass ratio). In addition, the viscosity of the mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink at a ratio of 7:100 (mass ratio) is higher than the viscosity of the mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink at a ratio of 7:100 (mass ratio). The recording medium is a liquid that has a viscosity of 30 msec from the start of contact in the Bristow method. 1 / 2 Water absorption up to 10mL / m 2 The method includes a first reaction liquid applying step, a first ink applying step, a second reaction liquid applying step, and a second ink applying step, in this order. The present inventors speculate that the mechanism by which the above configuration can prevent the ink from sinking into the image and improve the adhesion of the image is as follows.

[0016] The first reaction liquid and the second reaction liquid are aqueous reaction liquids containing a reactant that reacts with the ink. The first reaction liquid contains a water-soluble cationic resin. (i) The viscosity of the mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink at a ratio of 7:100 (mass ratio) is higher than the viscosity of the mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink at a ratio of 7:100 (mass ratio). (ii) The viscosity of the mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink at a ratio of 7:100 (mass ratio) is higher than the viscosity of the mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink at a ratio of 7:100 (mass ratio). Here, the viscosity of the mixed liquid obtained by mixing the reaction liquid and the ink at the above ratio by mass is a condition assuming the reactivity when the reaction liquid and the ink are applied to a recording medium and an image is recorded. The viscosity of the mixed liquid satisfying the relationship (i) means that the first reaction liquid has a higher reactivity with the first ink than the second reaction liquid. The viscosity of the mixed liquid satisfying the relationship (ii) means that the first reaction liquid is more reactive to the second ink than the second reaction liquid. The viscosity of the mixed liquid satisfying the relationships (i) and (ii) above can suppress the ink from being embedded in the image, as described above. If the relationship (i) above is not satisfied, it means that the reactivity of the first reaction liquid is lower than that of the second reaction liquid, or the reactivity of the first reaction liquid is equal to that of the second reaction liquid. If the reactivity of the first reaction liquid is lower than that of the second reaction liquid, or the reactivity of the first reaction liquid is equal to that of the second reaction liquid, it is not possible to suppress the ink from being embedded in the image, as described above. Furthermore, if the relationship (ii) above is not satisfied, it means that the second reaction liquid quickly aggregates the second ink, and the adhesion between the first ink layer and the second ink layer is not obtained. As a result, the adhesion of the image is not obtained.

[0017] By using the first reaction liquid containing a water-soluble cationic resin, the unevenness of the ink layer resulting from the increased reactivity is filled by the precipitated cationic resin. Then, the viscosity at the surface in contact with the recording medium is increased, and the adhesion of the image can be improved. If the first reaction liquid contains an organic acid or a polyvalent metal salt instead of a cationic resin as a reactant, the above-mentioned function of the cationic resin is not exerted, and the adhesion of the image cannot be obtained. When recording is performed on an absorbent recording medium, the liquid components of each reaction liquid and each ink are quickly absorbed into the recording medium, so that problems such as the second ink being buried in the first ink layer and the decrease in adhesion of the image do not occur.

[0018] <Inkjet recording method, inkjet recording apparatus, and set of aqueous ink and aqueous reaction liquid> The inkjet recording method of the present invention is a method in which an aqueous ink and an aqueous reaction liquid are ejected from an inkjet recording head by the action of thermal energy, and applied to a recording medium to record an image. The inkjet recording method of the present invention has a first reaction liquid application step, a first ink application step, a second reaction liquid application step, and a second ink application step, in this order. The first reaction liquid application step is a step of applying the first reaction liquid to a recording medium, and the first ink application step is a step of applying the first ink to an area to which the first reaction liquid is applied. The second reaction liquid application step is a step of applying the second reaction liquid to a recording medium, and the second ink application step is a step of applying the second ink to an area to which the second reaction liquid is applied. The first reaction liquid and the second reaction liquid are each an aqueous reaction liquid containing a reactant that reacts with the ink, and the first reaction liquid contains a water-soluble cationic resin. The first ink contains a pigment. The second ink contains at least one particulate component selected from the group consisting of pigments and resin particles.

[0019] The recording medium was exposed to the Bristow method for 30 msec. 1 / 2 Water absorption up to 10mL / m 2 The recording medium is as follows:

[0020] The inkjet recording apparatus of the present invention is an apparatus used in an inkjet recording method in which an aqueous ink and an aqueous reaction liquid are ejected from an inkjet recording head by the action of thermal energy and applied to a recording medium to record an image. The inkjet recording apparatus of the present invention is an apparatus suitable for use in the above-mentioned recording method. In the present invention, it is not necessary to provide a step of curing the image by irradiation with active energy rays or the like.

[0021] The set of aqueous ink and aqueous reaction liquid of the present invention is a set used in an inkjet recording method in which an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink are ejected from a recording head to record an image on a recording medium. The set is preferably used in the above-mentioned recording method. The form of the set includes a set of multiple ink cartridges each containing multiple inks (reaction liquids) independently, and an ink cartridge formed integrally by combining multiple ink containing parts each containing multiple inks (reaction liquids). The set of the present invention is not limited to the above form and may be in any form as long as it is configured so that the inks and reaction liquids can be used in combination.

[0022] The inkjet recording method and inkjet recording apparatus (hereinafter, also simply referred to as "recording method and recording apparatus") of the present invention will be described in detail below.

[0023] FIG. 1 is a perspective view showing an embodiment of an inkjet recording apparatus of the present invention. FIG. 2 is a side view showing an embodiment of an inkjet recording apparatus of the present invention. As shown in FIGS. 1 and 2, the recording apparatus of this embodiment includes an inkjet recording head 22 that ejects ink. The recording head 22 is a recording head that ejects ink by the action of thermal energy. A recording head that ejects ink by the action of thermal energy applies thermal energy to the ink by applying an electric pulse to an electrothermal conversion element, and ejects the ink from an ejection port. Here, a recording head that ejects ink by the action of thermal energy is taken as an example, but a recording head that ejects ink by the action of mechanical energy may also be adopted. The recording head may include a mechanism (temperature control mechanism) that heats the water-based ink ejected from the recording head. When the temperature control mechanism is provided, the heating temperature of the ink ejected from the recording head is preferably 35° C. or higher and 70° C. or lower. It is also preferable that the application of the first ink and the second ink, and the application of the first reaction liquid and the second reaction liquid to a unit area of ​​a recording medium are each performed by a plurality of relative scans of the recording head and the recording medium.

[0024] [Heating process] The recording method of the present invention may include a step of heating (heat treatment) the recording medium to which the ink has been applied. By heating the recording medium to which the ink has been applied, it is possible to promote drying and increase the strength of the image.

[0025] Examples of the means for heating the recording medium include known heating means such as a heater, air blowing means using air blowing such as a dryer, and a combination of these. Examples of the heating means include the above heating means, air blowing means, and a combination of these. Examples of the heat treatment method include a method of applying heat from the opposite side (back side) of the recording surface (ink application surface) of the recording medium using a heater, a method of applying warm or hot air to the recording surface of the recording medium, and a method of heating from the recording surface or back side using an infrared heater. A combination of these methods may also be used.

[0026] In order to enhance the abrasion resistance of the image, the heating temperature of the recording medium to which the ink and reaction liquid have been applied is preferably 50° C. or more and 90° C. or less. The heating temperature of the recording medium to which the ink has been applied may be read by a sensor incorporated in a position corresponding to the heating means of the recording device, or may be determined from the relationship between the amount of heat and the temperature of the recording medium, which is determined according to the type of ink and recording medium.

[0027] In the recording device shown in FIGS. 1 and 2, a heater 25 supported by a frame (not shown) is disposed downstream in the sub-scanning direction A from the position where the recording head 22 reciprocates in the main scanning direction B. The recording medium 1 to which ink has been applied can be heated by the heater 25. Specific examples of the heater 25 include a sheath heater and a halogen heater. The heater 25 is covered by a heater cover 26. The heater cover 26 is a member for efficiently irradiating the heat generated by the heater 25 to the recording medium 1. Furthermore, the heater cover 26 is also a member for protecting the heater 25. The recording medium 1 to which ink has been applied ejected from the recording head 22 is wound by a take-up spool 27 to form a roll-shaped wound medium 24.

[0028] 3 is a schematic diagram showing one embodiment of an 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.

[0029] The inkjet recording apparatus 100 of the embodiment shown in FIG. 3 is configured to include a first recording unit 1000, a heating unit 2000, a fixing unit 3000, a cooling unit 4000, a second recording unit 5000, an inverting unit 6000, and a paper discharge unit 7000. In the first recording unit 1000, various liquids are applied by a liquid application unit 1200 to a recording medium 1100 conveyed from a paper feed unit 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. After that, the recording medium 1100 is cooled by a cooling member 4100 of the cooling unit 4000. In the second recording section 5000, various liquids are applied to the recording medium 1100 by a liquid application device 5200. 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 6100 of the inversion section 6000. Next, after an image is recorded on the back side in the same manner as for the front side, the recording medium is transported by a transport member 7100 of the paper discharge section 7000 and stacked and stored in the recording medium storage section 7200.

[0030] [Recording Section] The first 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. Alternatively, 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 the reaction liquid 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 may include 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. From the viewpoint of image quality, it is preferable that the time until the reaction liquid comes into contact with the ink is short. Specifically, it is preferable that the time from when the reaction liquid is applied to when the ink is applied is 1100 milliseconds or less. The time from when the reaction liquid is applied to when the ink is applied can be adjusted by adjusting the interval between the application means or by adjusting the conveying speed. The above time may be the same or different between the first reaction liquid and the first ink, and between the second reaction liquid and the second ink.

[0031] 3, the application of the first ink and the second ink, and the first reaction liquid and the second reaction liquid to a unit area of ​​the recording medium may be performed by multiple relative scans of the recording head and the recording medium. In this case, from the viewpoint of forming a first ink layer, it is preferable that the application time difference between the application of the first ink and the second reaction liquid to a unit area on the recording medium is 5 seconds or more. If the application time difference is less than 5 seconds, the formation of the first ink layer may not be completed in time, and the ink may not be sufficiently suppressed from being buried in the image.

[0032] 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. 5) 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.

[0033] 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".

[0034] The second recording section 5000 includes a liquid applying device 5200. The liquid applying device 5200 includes a reaction liquid applying device 5201 and an ink applying device 5202. The second recording section may include the same components as those of the first recording section. The first recording section and the second recording section do not have to be separated as shown in FIG. 1. For example, a plurality of reaction liquid applying devices 1201 and ink applying devices 1202 may be arranged in the first recording section, and the recording medium may be returned to the first recording section downstream of the cooling section 4000 to perform recording. In that case, the reaction liquid applying device 1201 and the ink applying device 1202 used when passing through the first recording section 1000 for the first time may be the same as the reaction liquid applying device 1201 and the ink applying device 1202 used when passing through the second time, or may be different.

[0035] Fig. 4 is a perspective view showing an example of a liquid application device. The liquid application device 1200 shown in Fig. 4 is a line head, and a plurality of ejection element substrates 1203 each having an ejection port array are arranged in a straight line. The ejection element substrate 1203 has a plurality of ejection port arrays arranged thereon.

[0036] FIG. 5 is a cross-sectional perspective view showing an example of a discharge element substrate. The discharge element substrate 1203 shown in FIG. 5 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. 6, liquid chamber 1508). The second flow path 1209 is a region from a portion between the discharge port 1204 and the discharge element (FIG. 6, 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 a high-pressure inlet 1212 and a low-pressure outlet 1213, liquid can flow from the high-pressure side to the low-pressure side (in the direction of the arrow in FIG. 5). 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. 6) flows through the second flow path 1209 and the outlet 1213 to the outlet path 1211.

[0037] [Supply system] FIG. 6 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. 6 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.

[0038] 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.

[0039] 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. 6) is generated in which a 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. 5 indicate the flow of liquid inside the liquid chamber 1508. That is, as shown in Fig. 5, the liquid in the first flow path 1208 flows into the second flow path 1209 via the gap between the ejection port 1204 and the ejection element.

[0040] 6, 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. 5) communicating with the inflow channel 1210, and an outlet 1213 (FIG. 5) 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.

[0041] [Transport system] As shown in FIG. 3, the first 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 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 member 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 suctioning from the back side to fix the recording medium 1100, a method of forming the conveying member 1300 from an appropriate material and electrostatically adsorbing the recording medium 1100, and the like can be mentioned. The second recording unit 5000 can also be configured in the same manner as the first recording unit 1000.

[0042] [Heating section] As shown in Fig. 3, 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.

[0043] 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.

[0044] 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. 3 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.

[0045] 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).

[0046] Fig. 7 is a schematic diagram showing another example of the heating section. Here, the difference from the heating section shown in Fig. 7 and described above will be described. The heating section 2000 shown in Fig. 7 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.

[0047] 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. 3) 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. 3) 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).

[0048] An air knife 2300 is disposed between the transport member 1300 (FIG. 3) 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. 3). 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. 3), and to suppress transport failures.

[0049] 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.

[0050] [Fixing section] As shown in FIG. 3, 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 .

[0051] 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.).

[0052] 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.

[0053] 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.

[0054] FIG. 8 is a schematic diagram showing another example of the fixing unit. Here, the difference from the fixing unit shown in FIG. 3 and described above will be described. The fixing unit 3000 shown in FIG. 8 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.

[0055] [Cooling section] The cooling section 4000 is configured to include a cooling member 4100 and a conveying member 4200 (FIG. 3). The cooling section 4000 cools the recording medium 1100, which has passed through the heating section 2000 and the fixing section 3000 and is heated to a high temperature. 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 increase the 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).

[0056] The heating unit, fixing unit, and cooling unit may be provided after the second recording unit 5000. In this case, they may have the same configuration as the heating unit, fixing unit, and cooling unit, or may have different configurations.

[0057] [Inverted part] When performing double-sided recording, the recording medium 1100 is inverted using the inversion unit 6000 (FIG. 3). 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 6100. 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)).

[0058] [Paper output section] After the image is recorded, the recording medium 1100 is stored in a paper discharge section 7000 (FIG. 3). 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 7100, and is finally stored in a stacked state in a recording medium storage section 7200. Two or more recording medium storage sections 7200 may be provided to store different recorded materials, etc.

[0059] (Recording medium) In the recording method and recording device of the present invention, a non-absorbent recording medium (a low to non-absorbent recording medium) is used. The low to non-absorbent recording medium is a recording medium that is absorbed within 30 msec from the start of contact in the Bristow method described in JAPAN TAPPI Paper Pulp Test Method No. 51 "Liquid Absorbency Test Method for Paper and Paperboard". 1 / 2 Water absorption up to 0mL / m 2 More than 10mL / m 2 In the present invention, a recording medium that satisfies the above-mentioned condition of water absorption amount is defined as a "low to non-absorbent recording medium". A recording medium for inkjet recording having a coating layer (ink receiving layer) formed of inorganic particles (glossy paper, matte paper, etc.) and plain paper having no coating layer have a water absorption amount of 10 mL / m 2 It is an "absorbent recording medium" that exceeds this.

[0060] As the low to non-absorbent recording medium, a plastic film; a recording medium in which a plastic film is bonded to the recording surface of a substrate; a recording medium in which a resin coating layer is provided on the recording surface of a substrate containing cellulose pulp; and the like can be used. Among these, a plastic film is preferred, and a recording medium in which a resin coating layer is provided on the recording surface of a substrate containing cellulose pulp is also preferred. Note that the recording medium in this specification does not refer to a transfer body, but refers to a recording medium on which an image as a recorded matter is recorded.

[0061] <First reaction solution> The recording method of the present invention has a reaction liquid application step (first reaction liquid application step) of applying an aqueous reaction liquid containing a reactant that reacts with an aqueous ink to a recording medium. Each component used in the first reaction liquid will be described in detail below.

[0062] [Reactants] The first reaction liquid reacts with the ink by contacting 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 a recording medium, and can promote the aggregation of the ink. The first reaction liquid contains a water-soluble cationic resin as a reactant. The content (mass%) of the reactant including the water-soluble cationic resin in the first reaction liquid is preferably 0.1 mass% or more and 40.0 mass% or less, and more preferably 1.0 mass% or more and 20.0 mass% or less, based on the total mass of the reaction liquid. The reactant may be used alone or in combination of two or more. Examples of other reactants include polyvalent metal salts and organic acids. The first reaction liquid preferably further contains at least one reactant selected from the group consisting of polyvalent metal salts and organic acids.

[0063] [Water-soluble cationic resin] A water-soluble cationic resin (hereinafter, simply referred to as a cationic resin) is a reactant that has a cationic site in the resin structure and aggregates the pigment in the ink. Examples of the cationic resin include resins having a primary to tertiary amine structure and resins having a quaternary ammonium salt structure. Among them, the cationic resin of the first reaction liquid is preferably a resin having a quaternary ammonium salt structure. Specifically, examples of the cationic resin include resins having structures such as vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensate. In order to increase the solubility in the reaction liquid, the cationic resin may be used in combination with an acidic compound or the cationic resin may be subjected to a quaternary treatment.

[0064] The weight average molecular weight of the cationic resin is preferably 500 or more and 50,000 or less. The weight average molecular weight of the cationic resin can be measured, for example, as a value converted into polystyrene by gel permeation chromatography. In particular, the weight average molecular weight of the cationic resin is more preferably 30,000 or less. If the weight average molecular weight of the cationic resin exceeds 30,000, it forms large aggregates when reacting with the ink, making it difficult for the cationic resin to move, and there are cases in which sufficient adhesion of the image cannot be obtained. The content (mass %) of the cationic resin in the first reaction liquid is preferably 0.1 mass % or more and 10.0 mass % or less, and more preferably 0.1 mass % or more and 5.0 mass % or less, based on the total mass of the reaction liquid.

[0065] The cationic resin preferably has a cationic degree (meq / g) of 3 meq / g or more and 7 meq / g or less. If the cationic degree is less than 3 meq / g, the effect of agglomerating pigments and the like is weak, and the ink may not be sufficiently suppressed from being buried in the image. On the other hand, if the cationic degree is more than 7 meq / g, the effect of agglomerating pigments and the like is too strong, which may cause unevenness between the recording medium and the image, and the image may not have sufficient adhesion. The cationic degree is an index of the degree of cationicity of the resin, and is expressed by the number of millimoles of cationic groups per gram of resin, and the higher the cationic degree, the higher the number of moles of cationic groups.

[0066] The cationic degree of the cationic resin can be measured by colloid titration at 25° C. In the examples described later, the cationic degree of the cationic resin was measured by colloid titration using an automatic potentiometric titrator (product name "AT-510", manufactured by Kyoto Electronics Manufacturing Co., Ltd.) and a 1 / 400N potassium polyvinyl sulfate solution (manufactured by Fujifilm) as a titration reagent. The aqueous solution of the cationic resin used in the titration may be prepared by dissolving the cationic resin appropriately taken out from the first reaction solution in water.

[0067] [Polyvalent metal salt] Polyvalent metal salts are compounds formed from divalent or higher metal ions (polyvalent metal ions) and anions. Polyvalent metal salts dissociate in an aqueous reaction solution to produce polyvalent metal ions, and are therefore reactants that aggregate pigments in ink.

[0068] 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+ Among them, from the viewpoint of reactivity with ink, Ca 2+ and Mg2+ It is preferable to use at least one metal ion selected from the group consisting of:

[0069] In order to make the first reaction solution contain polyvalent metal ions, 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 - Among them, the polyvalent metal salt in the reaction solution is calcium lactate (Ca 2+ and CH3CH(OH)COO - A combination of magnesium sulfate (Mg 2+ and SO4 2- The polyvalent metal salt is preferably at least one compound selected from the group consisting of: (a combination of the above) By using the polyvalent metal salt, the reactivity with the ink can be further improved.

[0070] When a polyvalent metal ion is used as a reactant, the content (mass%) of the first reaction liquid calculated as polyvalent metal salt is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction liquid. In this specification, when the polyvalent metal salt is a hydrate, the "content (mass%) of the polyvalent metal salt in the reaction liquid means the "content (mass%) of the anhydride of the polyvalent metal salt" excluding water as the hydrate.

[0071] [Organic acid] The reaction liquid containing an organic acid as a reactant 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.

[0072] When an organic acid is used as a reactant, it is preferable to use a polycarboxylic acid from the viewpoint of more effectively suppressing the ink from being buried in the image. In other words, it is preferable that the organic acid used as the reactant is a polycarboxylic acid. When a monocarboxylic acid with low water solubility is used as a reactant, it is easy to precipitate due to the evaporation of the liquid components of the ink before it is applied to the recording medium, and it may not be possible to fully exert the function of making the anionic group into an acid type. As a result, it may not be possible to fully suppress the ink from being buried in the image. In addition, even if a monocarboxylic acid with high water solubility is used as a reactant, it may not be possible to fully exert the function of making the anionic group into an acid type, as described above, because it is highly volatile. As a result, it may not be possible to fully suppress the ink from being buried in the image.

[0073] The acid dissociation constant (pKa) of the organic acid at 25°C is preferably 5.0 or less. pKa indicates the ease of dissociation of the proton of the acid. When the organic acid has multiple anionic groups (carboxylic acid groups), it has multiple pKas, but the amount of the organic acid dissociated in the reaction solution can be said to depend on the first acid dissociation constant (pKa1). Therefore, in this specification, the acid dissociation constant of an organic acid having multiple anionic groups refers to the first acid dissociation constant. If the pKa of the organic acid is more than 5.0, the effect of aggregating the pigment becomes weak, and the ink may not be sufficiently suppressed from being buried in the image. The content (mass%) of the organic acid in the first reaction solution is preferably 1.0 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 reaction solution.

[0074] [Aqueous medium] The first reaction liquid is an aqueous reaction liquid containing at least water as an aqueous medium. The aqueous medium used in the reaction liquid may contain a water-soluble organic solvent that can be contained in the ink, as described below.

[0075] [Other ingredients] The first reaction liquid may contain various other components as necessary, such as the other components that can be contained in the inks (first ink and second ink) and will be described later.

[0076] [Physical properties of reaction solution] The first reaction liquid that can be suitably used in the recording method of the present invention is an aqueous reaction liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control its 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, more preferably 6.0 or more and 9.0 or less.

[0077] The viscosity of the mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink at a ratio of 7:100 (mass ratio) is higher than the viscosity of the mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink at a ratio of 7:100 (mass ratio). The viscosity of the mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink at a ratio of 7:100 (mass ratio) is higher than the viscosity of the mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink at a ratio of 7:100 (mass ratio). In particular, from the viewpoint of controlling the reactivity, the viscosity of the mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink at a ratio of 7:100 (mass ratio) is preferably at least twice the viscosity of the mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink at a ratio of 7:100 (mass ratio). The second reaction liquid, the first ink, and the second ink will be described in detail later. The viscosity of the mixed liquid may be measured, for example, by adding the reaction liquid and the ink in the above ratio to a suitable container such as a beaker at 25°C and thoroughly stirring the mixture. As long as the reaction can be sufficiently progressed, any stirring method may be used, such as using a stirrer. In the examples described below, the viscosity at the time of mixing was measured by mixing the liquids and using a vortex mixer (product name "TUBE MIXER TM-2N", manufactured by AS ONE) to stir for 10 seconds at a scale of 10, and then measuring the viscosity. The viscosity can be measured using a rotational viscometer, and in the examples described below, an E-type viscometer (product name "RE-80L", manufactured by Toki Sangyo) was used.

[0078] The viscosity of the mixed liquid can be adjusted, for example, by the content of the reactant, the content of the cationic resin, the molecular weight of the cationic resin, the cationic degree, the valence of the organic acid used in combination, and the like. It can also be adjusted by the ink used in combination. For example, when the ink contains a self-dispersed pigment, it can be adjusted by the density of the carboxylic acid group bonded directly or via another atomic group to the surface of the pigment particles. When the ink contains a resin-dispersed pigment, it can be adjusted by the acid value of the resin dispersant used, the ratio of the pigment to the resin dispersant, and the like. Furthermore, it can also be adjusted by the acid value and content of the resin particles that may be added to the ink, the acid value and content of the water-soluble resin, and the like. In order to increase the viscosity when mixed, it is sufficient to increase the size of the aggregates generated by the reaction or increase the amount of the aggregates. For this purpose, there are methods such as increasing the density of the anionic group (carboxylic acid group) of the self-dispersed pigment, increasing the acid value of the resin dispersant of the resin-dispersed pigment, increasing the acid value of the resin particles, and increasing the acid value of the water-soluble resin.

[0079] <Second reaction solution> The recording method of the present invention has a reaction liquid application step (second reaction liquid application step) of applying an aqueous reaction liquid containing a reactant that reacts with the aqueous ink to a recording medium. Each component used in the second reaction liquid will be described in detail below.

[0080] [Reactants] The second reaction liquid reacts with the ink when it comes into contact with the ink, and causes the components in the ink (components having anionic groups, such as resins, surfactants, and self-dispersing pigments) to aggregate, and contains a reactant. The presence of the reactant destabilizes the state of the components in the ink having anionic groups when the ink and the reactant come into contact with each other on the recording medium, and can promote the aggregation of the ink.

[0081] The second reaction liquid can be appropriately selected from the reactants listed above as usable for the first reaction liquid. The content (mass%) of the reactant in the second reaction liquid is preferably 0.1% by mass or more and 40.0% by mass or less based on the total mass of the reaction liquid. In particular, the second reaction liquid preferably contains a water-soluble cationic resin. By containing a water-soluble cationic resin in the second reaction liquid, the conformability to the first ink layer formed by the first reaction liquid and the first ink is improved, and the adhesion of the image can be further improved. In addition, when the second reaction liquid contains a water-soluble cationic resin, the content (mass%) of the cationic resin in the first reaction liquid is preferably larger than the content (mass%) of the cationic resin in the second reaction liquid. In particular, the difference between the content (mass%) of the cationic resin in the first reaction liquid and the content (mass%) of the cationic resin in the second reaction liquid is preferably 1.0% or more. By making the difference in cationic resin content between the first reaction liquid and the second reaction liquid 1.0% or more, the difference in reactivity between the first reaction liquid and the second reaction liquid becomes greater, and the ink can be further prevented from being embedded in the image.

[0082] The content (mass%) of the reactant in the first reaction liquid is preferably greater than the content (mass%) of the reactant in the second reaction liquid, and more preferably the difference between the content (mass%) of the reactant in the first reaction liquid and the content (mass%) of the reactant in the second reaction liquid is 1.0% or more.

[0083] [Aqueous medium] The second reaction liquid is an aqueous reaction liquid containing at least water as an aqueous medium. The aqueous medium used in the reaction liquid may contain a water-soluble organic solvent, which can be contained in the ink (the first ink or the second ink), as described below.

[0084] [Other ingredients] The second reaction liquid may contain various other components as necessary, such as the other components that can be contained in the inks (the first ink and the second ink) and will be described later.

[0085] [Physical properties of reaction solution] The second reaction liquid that can be suitably used in the recording method of the present invention is an aqueous reaction liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control its 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, more preferably 6.0 or more and 9.0 or less.

[0086] The surface tension of the second reaction liquid is preferably higher than that of the first reaction liquid. If the surface tension of the first reaction liquid is higher than that of the second reaction liquid, the probability of contact between the first reaction liquid and the first ink decreases, and the reactivity with the first ink may not be sufficiently obtained. As a result, the ink may not be sufficiently suppressed from being buried in the image. In particular, the difference between the surface tension of the second reaction liquid and the surface tension of the first reaction liquid is preferably 1.0 mN / m or more. The surface tension can be measured by a surface tensiometer using a plate method.

[0087] <First ink> The first ink used in the recording method of the present invention is a pigment-containing water-based ink for ink-jet recording. Each of the components constituting the first ink will be described in detail below.

[0088] [Colorant] The first ink contains a pigment as a coloring material. The content (mass %) of the pigment in the ink is preferably from 0.1% to 20.0% by mass, and more preferably from 1.0% to 15.0% by mass, based on the total mass of the ink.

[0089] 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.

[0090] 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.

[0091] 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 a resin as described below, especially a water-soluble resin, can be used. 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 of the resin dispersant.

[0092] 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.

[0093] The pigment of the first ink is preferably titanium oxide. Titanium oxide, which is commonly used as a coloring material for water-based inkjet inks, tends to have a larger particle size than other pigments in order to produce whiteness. Therefore, when titanium oxide is used as the pigment of the first ink, it is thought that the large particle size of the titanium oxide can prevent the ink from being buried in the image when the second ink is applied on top of the first ink, which is likely to be the cause of the ink being buried in the image when the second ink is applied on top of the first ink.

[0094] Inorganic oxides such as titanium oxide react with water molecules constituting the aqueous medium in the aqueous ink to generate hydroxyl groups (hereinafter, sometimes referred to as "surface hydroxyl groups") on the surface. For this reason, in the case of aqueous inkjet inks, in order to utilize the generated surface hydroxyl groups while further improving the storage stability of the ink, the ink is generally used in a state where the ink is surface-treated with inorganic oxides such as alumina or silica. The surface hydroxyl groups of titanium oxide particles have properties specific to the inorganic oxide corresponding to the inorganic compound used in the surface treatment, and the isoelectric point, which is an indicator of the strength of the acid, differs depending on the type of inorganic compound. Therefore, although titanium oxide itself is an inorganic oxide, the surface of titanium oxide particles shows the properties of an inorganic oxide corresponding to the inorganic compound used in the surface treatment, and the surface charge of titanium oxide particles is strongly dependent on the pH of the aqueous medium, the type of surface treatment agent, and the amount of the surface treatment agent used.

[0095] Titanium oxide is a white pigment, and has three crystal forms: rutile, anatase, and brookite. Among them, rutile titanium oxide is preferred. Titanium oxide can be industrially produced by the sulfuric acid method and the chlorine method, and the titanium oxide used in the present invention may be produced by either method.

[0096] Titanium oxide may be surface-coated (surface-treated) with an inorganic oxide or an organic substance. In particular, titanium oxide surface-treated with alumina and silica is preferably used. The surface treatment is expected to suppress photocatalytic activity and improve dispersibility. In this specification, "alumina" is a general term for oxides of aluminum such as aluminum oxide. In this specification, "silica" is a general term for silicon dioxide or a substance composed of silicon dioxide. Most of the alumina and silica that coat titanium oxide are present in the form of silicon dioxide and aluminum oxide.

[0097] The ratio of alumina and silica in titanium oxide particles, i.e., the amount of alumina and silica coating, can be measured, for example, by quantitative analysis of aluminum and silicon elements by inductively coupled plasma (ICP) emission spectrometry. In this case, it is assumed that all atoms coating the surface are in the form of oxides, and the obtained values ​​of aluminum and silicon can be converted to the oxides, i.e., alumina and silica, to calculate the amount of alumina and silica.

[0098] Surface treatment methods for titanium oxide include wet treatment and dry treatment. For example, titanium oxide can be dispersed in a liquid medium and then reacted with a surface treatment agent such as sodium aluminate or sodium silicate to perform surface treatment, and the desired characteristics can be achieved by appropriately changing the ratio of these surface treatment agents. In addition to alumina and silica, inorganic oxides such as zinc oxide and zirconia, and organic substances such as polyols can also be used for surface treatment, as long as the effects of the present invention are not impaired.

[0099] [resin] The first ink may contain a resin. By using an ink containing a resin, an image with improved abrasion resistance may be recorded. The resin may be added to the ink (i) to stabilize the dispersion state of the pigment, that is, as a resin dispersant or its auxiliary, or (ii) to improve various properties of the recorded image.

[0100] The content (mass %) of the resin in the first 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 a water-soluble resin that can be dissolved in an aqueous medium, or may be resin particles that are dispersed in an aqueous medium. The resin may be used alone or in combination of two or more kinds. In particular, it is preferable that the first ink further contains a water-soluble resin. It is considered that the inclusion of a water-soluble resin can improve the reactivity with the first reaction liquid and improve the adhesion to the recording medium.

[0101] When the first ink contains resin particles, the reactivity of the first ink can be adjusted, for example, by the density of the anionic groups of the resin particles, the acid value of the resin that constitutes the resin particles, etc. To increase the viscosity when mixed, there are methods such as increasing the density of the carboxylic acid groups of the resin particles or increasing the acid value of the resin particles.

[0102] [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.

[0103] The acrylic resin preferably has a hydrophilic unit and a hydrophobic unit as constituent units. Among them, a resin having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one monomer selected from the group consisting of a monomer having an aromatic ring and a (meth)acrylic acid ester monomer is preferred. In particular, a resin having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one monomer selected from the group consisting of styrene and α-methylstyrene is preferred. These resins are likely to interact with pigments, and therefore can be suitably used as a resin dispersant for dispersing pigments.

[0104] 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. The hydrophobic unit is a unit not having a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer not having 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, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0105] 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.

[0106] [Resin properties] In this specification, "a resin is water-soluble" means that when the resin is neutralized with an alkali equivalent to the acid value, the resin is present in an aqueous medium in a state in which it does not form particles whose particle size can be measured by a dynamic light scattering method. Whether or not a resin is water-soluble 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 size of the resin in the sample solution is measured by a dynamic light scattering method, if no particles having a particle size are 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. In addition, a particle size analyzer using a dynamic light scattering method (for example, the product name "UPA-EX150", manufactured by Nikkiso) can be used as a particle size distribution measuring device. Of course, the particle size distribution measuring device and the measurement conditions are not limited to those described above.

[0107] 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.

[0108] 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 particle size analyzer and measurement conditions described above using the dynamic light scattering method. 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.

[0109] [Wax particles] The first 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 water-soluble resin. The wax may be used alone or in combination of two or more kinds. The content (mass %) of the wax particles in the first 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.

[0110] 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 recording method of 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).

[0111] 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.

[0112] 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.

[0113] [Aqueous medium] The first ink used in the recording method of the present invention is an aqueous ink containing at least water as an aqueous medium. The first 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 first 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 first ink is preferably 3.0 mass% or more and 50.0 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, may be used. The water-soluble organic solvent may be used alone or in combination of two or more.

[0114] [Other ingredients] The first ink may contain various other components as necessary. Examples of other components include various additives such as antifoaming agents, surfactants, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors. However, it is preferable that the first ink does not contain a reactant to be contained in the reaction liquid.

[0115] [Ink properties] The first 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.

[0116] <Second ink> The second ink used in the recording method of the present invention is an aqueous inkjet ink containing at least one particulate material selected from the group consisting of pigments and resin particles. In other words, the second ink may be an ink that does not contain a pigment but contains resin particles. Such an ink is also called a clear ink. Each component constituting the second ink will be described in detail below.

[0117] [Colorant] The second ink preferably contains a pigment as a coloring material. The content (mass %) of the pigment in the second ink is preferably from 0.1% to 20.0% by mass, more preferably from 1.0% to 15.0% by mass, based on the total mass of the ink.

[0118] 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.

[0119] The pigment may be appropriately selected from those listed as usable for the first ink. The properties of the pigment may be determined in the same manner as those listed as usable for the first ink. In particular, the pigment as the particulate matter of the second ink is preferably at least one selected from the group consisting of carbon black and organic pigments. In other words, it is preferable that the first ink is a white ink and the second ink is a color ink (non-white ink). As described above, the second ink may not contain a pigment. Therefore, the first ink may be a white ink and the second ink may be a clear ink that does not contain a pigment.

[0120] [resin] The second ink contains at least one selected from the group consisting of pigments and resin particles. The second ink preferably further contains a water-soluble resin that is soluble in an aqueous medium. In this case, the acid value of the water-soluble resin in the first ink is preferably higher than the acid value of the water-soluble resin in the second ink. In particular, the difference between the acid value of the water-soluble resin in the first ink and the acid value of the water-soluble resin in the second ink is preferably 50 mgKOH / g or more. The acid value of the resin can be measured based on JIS K-0070.

[0121] The resin can be appropriately selected from those listed as usable for the first ink, and its properties can be determined in the same manner as those listed as usable for the first ink.

[0122] [Wax particles] The second 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 second 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.

[0123] The wax may be appropriately selected from those listed as usable for the first ink, and its properties may be determined in the same manner as those listed as usable for the first ink.

[0124] [Aqueous medium] The second ink used in the recording method of the present invention is an aqueous ink containing at least water as an aqueous medium. The second 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 second 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 second 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, may be used. The water-soluble organic solvent may be used alone or in combination of two or more.

[0125] [Other ingredients] The second ink may contain various other components as necessary. Examples of other components include various additives such as antifoaming agents, surfactants, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors. However, it is preferable that the second ink does not contain a reactant to be contained in the reaction liquid.

[0126] [Ink properties] The second 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

[0127] 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.

[0128] <Measurement of physical properties> (Viscosity of the mixture) The viscosity was measured when each reaction liquid and each ink were mixed at a mass ratio of 7:100 as follows. First, the reaction liquid and the ink were mixed at the above mass ratio. Then, using a vortex mixer (product name "TUBE MIXER TM-2N", manufactured by AS ONE), the mixture was stirred for 10 seconds at a setting of 10, and the viscosity was measured. An E-type viscometer (product name "RE-80L", manufactured by Toki Sangyo) was used to measure the viscosity.

[0129] (Acid value of resin) The acid value of the resin was measured by titration based on JIS K-0070. 0.5 to 2.0 g of the resin was precisely weighed and used as the sample to be measured. The sample was placed in a 50.0 mL beaker, and 25.0 mL of a mixture of tetrahydrofuran and ethanol (volume ratio = 2:1) was added to dissolve the sample. A 0.1 mol / L ethanol solution of potassium hydroxide was used as the titrant, and titration was performed by potentiometric titration, and the amount of titrant used was defined as S (mL). A blank not containing the sample was also titrated in the same manner, and the amount of the ethanol solution of potassium hydroxide used was defined as B (mL). An automatic titration device (trade name "COM-2500", manufactured by Hiranuma Sangyo Co., Ltd.) was used as the measuring device. The acid value was calculated from the obtained S and B using the following formula. f is the factor (titer) of the ethanol solution of potassium hydroxide, and M (g) is the precisely weighed value of the sample. Acid value [mgKOH / g]=(SB)×f×5.61 / M <Preparation of reaction solution> The components (unit: %) shown in Tables 1 to 6 were mixed and thoroughly stirred, and then pressure filtered through a cellulose acetate filter (manufactured by Advantec) with a pore size of 3.0 μm to prepare the first and second reaction solutions, respectively. In Tables 1 to 6, "Catiomaster PDT-2", "Catiomaster PD-7", and "Catiomaster PD-30" are the trade names of aqueous solutions of amine-epichlorohydrin condensation polymers manufactured by Yokkaichi Chemicals. "Acetylenol E60" is the trade name of a nonionic surfactant manufactured by Kawaken Fine Chemicals. "PAS-2401" is the trade name of an aqueous solution of diallyl methylethyl ammonium ethyl sulfate-sulfur dioxide copolymer manufactured by Nittobo Medical. "PAS-A-5" and "PAS-H-1L" are the trade names of aqueous solutions of diallyl dimethyl ammonium chloride manufactured by Nittobo Medical. "Polyquat40u05NV" is the trade name of an aqueous solution of diallyldimethylammonium chloride manufactured by Katpol GmbH. "PAA-HCL-01" is the trade name of an aqueous solution of allylamine hydrochloride polymer manufactured by Nittobo Medical. "PAS-92" is the trade name of an aqueous solution of diallylamine hydrochloride-sulfur dioxide copolymer manufactured by Nittobo Medical. "PAS-M-1L" is the trade name of an aqueous solution of methyldiallylamine acetate polymer manufactured by Nittobo Medical. "Proxel GXL(S)" is the trade name of a preservative manufactured by Arch Chemicals. The surface tension γ (mN / m) of the reaction solution is the static surface tension value measured using a Wilhelmy type surface tensiometer (trade name "Automatic Surface Tensiometer CBVP-Z", manufactured by Kyowa Interface Science) at 25°C.

[0130] Details of the cationic resin used in the preparation of the first reaction liquid and the second reaction liquid are shown below. Cation Master PDT-2 (product name): Yokkaichi Chemical Co., Ltd., weight average molecular weight: 1,000, cationic degree: 7 meq / g, resin content: 60.0%, quaternary ammonium salt Cation Master PD-7 (product name): Yokkaichi Chemical Co., Ltd., weight average molecular weight: 5,000, cationic degree: 7 meq / g, resin content: 50.0%, quaternary ammonium salt Cation Master PD-30 (product name): Yokkaichi Chemical Co., Ltd., weight average molecular weight: 9,000, cationic degree: 7 meq / g, resin content: 50.0%, quaternary ammonium salt PAS-2401 (product name): manufactured by Nittobo Medical, weight average molecular weight: 2,000, cationic degree: 2 meq / g, resin content: 25.0%, quaternary ammonium salt PAS-A-5 (product name): manufactured by Nittobo Medical, weight average molecular weight: 4,000, cationic degree: 3 meq / g, resin content: 40.0%, quaternary ammonium salt PAS-H-1L (product name): manufactured by Nittobo Medical, weight average molecular weight: 8,500, cationic degree: 5 meq / g, resin content: 28.0%, quaternary ammonium salt Polyquat40u05NV (product name): manufactured by Katpol GmbH, average molecular weight: 4,000, cationic degree: 6 meq / g, resin content: 40.0%, quaternary ammonium salt PAA-HCL-01 (product name): manufactured by Nittobo Medical, weight average molecular weight: 1,600, cationic degree: 9 meq / g, resin content: 33.0%, primary amine PAS-92 (product name): manufactured by Nittobo Medical, average molecular weight: 5,000, cationic degree: 5 meq / g, resin content: 20.0%, secondary amine PAS-M-1L (product name): manufactured by Nittobo Medical, weight average molecular weight: 5,000, cationic degree: 5 meq / g, resin content: 25.0%, tertiary amine

[0131] [Table 1]

[0132] [Table 2]

[0133] [Table 3]

[0134] [Table 4]

[0135] [Table 5]

[0136] [Table 6]

[0137] <Preparation of pigment dispersion> (Pigment dispersion 1) A styrene-ethyl acrylate-acrylic acid copolymer (resin 1) with an acid value of 100 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%. 15.0 parts of pigment (carbon black), 22.5 parts of the aqueous solution of resin 1, and 62.5 parts of pure water were mixed to obtain a mixture. 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 (manufactured by Advantec) with a pore size of 3.0 μm to prepare pigment dispersion 1 with a pigment content of 15.0% and a resin dispersant (resin 1) content of 4.5%.

[0138] (Pigment dispersion 2) Pigment dispersion 2 was prepared using the same procedure as for pigment dispersion 1 described above, except that resin 1 was changed to a resin (resin 2) with an acid value of 150 mg KOH / g and a weight-average molecular weight of 7,000. The pigment dispersion 2 had a pigment content of 15.0% and a resin dispersant (resin 2) content of 4.5%.

[0139] (Pigment dispersion 3) A solution of 5.0 g of concentrated hydrochloric acid in 5.5 g of water was cooled to 5°C, and 1.5 g of 4-aminophthalic acid was added. The container containing this solution was placed in an ice bath, and while stirring to keep the temperature of the solution below 10°C, a solution obtained by dissolving 0.9 g of sodium nitrite in 9.0 g of ion-exchanged water at 5°C was added. After stirring for 15 minutes, 6.0 g of carbon black was added under stirring, and the mixture was stirred for another 15 minutes to obtain a slurry. The obtained slurry was filtered with filter paper (product name "Standard Filter Paper No. 2", Advantec), the particles were thoroughly washed with water, and dried in an oven at 110°C. Thereafter, sodium ions were replaced with potassium ions by ion exchange to obtain a self-dispersing pigment in which -C6H3-(COOK)2 groups were bonded to the pigment particle surface. An appropriate amount of pure water was added to adjust the pigment content, and a pigment dispersion 3 with a pigment content of 15.0% was obtained.

[0140] (Pigment Dispersion 4) Pigment dispersion 4 was prepared using the same procedure as for pigment dispersion 1 described above, except that the pigment was changed to CI Pigment Blue 15:3. The pigment content was 15.0% and the resin dispersant (resin 1) content was 4.5%.

[0141] (Pigment Dispersion 5) Pigment dispersion 5 was prepared using the same procedure as for pigment dispersion 1 described above, except that the pigment was changed to CI Pigment Red 122. The pigment content was 15.0% and the resin dispersant (resin 1) content was 4.5%.

[0142] (Pigment Dispersion 6) Pigment dispersion 6 was prepared using the same procedure as for pigment dispersion 1 described above, except that the pigment was changed to CI Pigment Yellow 74. The pigment content was 15.0% and the resin dispersant (resin 1) content was 4.5%.

[0143] (Pigment Dispersion 7) 40.0 parts of rutile titanium dioxide (product name "TITANIX JR-403", surface treatment: alumina, silica), 1.2 parts of 3-(methoxy(polyoxyethylene)9-12)propyltrimethoxysilane, and ion-exchanged water making up a total of 100.0 parts of the components were mixed and pre-dispersed using a homogenizer. Then, using 0.5 mm zirconia beads, a dispersion treatment was carried out at 25°C for 12 hours using a paint shaker. The zirconia beads were filtered off, and an appropriate amount of ion-exchanged water was added as necessary to prepare pigment dispersion 7 with a pigment (titanium dioxide particles) content of 40.0%.

[0144] (Pigment Dispersion 8) Pigment dispersion 8, which had a pigment (titanium oxide particles) content of 40.0%, was prepared in the same manner as for pigment dispersion 7, except that the pigment was changed to rutile-type titanium oxide (product name "TITANIX JR-800", surface treatment: alumina, silica).

[0145] <Production of resin particles> (Aqueous dispersion of resin particles 1) In a four-neck flask equipped with a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 78.8 parts of ion-exchanged water and 0.2 parts of potassium persulfate (polymerization initiator) were placed, and nitrogen gas was introduced and stirred, and the temperature was raised to 80 ° C. A mixture of 2.3 parts of methacrylic acid, 90.0 parts of butyl methacrylate, and 90.0 parts of methyl methacrylate and a solution of 1.3 parts of t-butyl peroxide (polymerization initiator) were dropped over 2 hours. After aging for 2 hours, the mixture was cooled to 25 ° C. An appropriate amount of potassium hydroxide and ion-exchanged water were added to adjust the pH to 8.5, and an aqueous dispersion of resin particles 1 with a resin (solid content) content of 30.0% was obtained. The acid value of the resin constituting resin particles 1 was 8.2 mg KOH / g.

[0146] (Aqueous dispersion of resin particles 2) An aqueous dispersion of resin particles 2 having a resin (solid content) content of 30.0% was obtained in the same manner as in the aqueous dispersion of resin particles 1, except that 1.6 parts of methacrylic acid, 95.0 parts of butyl methacrylate, and 95.0 parts of methyl methacrylate were used. The acid value of the resin constituting resin particles 2 was 5.4 mgKOH / g.

[0147] <Preparation of wax particles> 25.0 parts of a commercially available Fischer-Tropsch wax (product name "FT-0165", melting point 73°C, manufactured by Nippon Seiro Co., Ltd.) and 5.0 parts of polyoxyethylene (15) cetyl ether were mixed, and the temperature and pressure were appropriately adjusted to disperse the wax. An appropriate amount of ion-exchanged water was added to dilute the mixture, and an aqueous dispersion of wax particles 1 with a wax particle content of 30.0% was obtained.

[0148] <Ink Preparation> The components (unit: %) shown in Tables 7 to 10 were mixed and thoroughly stirred, and then pressure filtered using a cellulose acetate filter (manufactured by Advantec) with a pore size of 3.0 μm to prepare the first ink and the second ink. However, the inks using Pigment Dispersions 7 and 8 were pressure filtered using a cellulose acetate filter (manufactured by Advantec) with a pore size of 5.0 μm. In Tables 7 to 10, "Joncryl 683" is the trade name of an acrylic resin (weight average molecular weight approximately 8,000, acid value 160 mgKOH / g) manufactured by BASF Japan. "Joncryl 819" is the trade name of an acrylic resin (weight average molecular weight approximately 15,000, acid value 75 mgKOH / g) manufactured by BASF Japan.

[0149] [Table 7]

[0150] [Table 8]

[0151] [Table 9]

[0152] [Table 10]

[0153] <Evaluation> The prepared reaction liquid and ink were filled in a cartridge, and the cartridge was set in an inkjet recording device (product name "imagePROGRAF PRO-2000", manufactured by Canon) equipped with a recording head that ejects ink by thermal energy. A heating device for drying the recording medium to which the reaction liquid and ink were applied by blowing air was incorporated in this recording device at a position downstream of the recording head in the conveying direction of the recording medium. The surface temperature of the recording medium was set to 80°C by heating with the heating device. The recording environment was set to a temperature of 25°C and a relative humidity of 50%. In this example, an image recorded under the condition that one drop of 4.0 ng of ink was applied to a unit area of ​​1 / 1200 inch x 1 / 1200 inch is defined as having a recording duty of 100%. Under the conditions shown in Tables 11 and 12, a 5 cm x 5 cm solid image was recorded with a recording duty of 10% for the first reaction liquid and a recording duty of 100% for the first ink. Thereafter, a 5 cm x 5 cm solid image was recorded so as to overlap the solid image, with the second reaction liquid having a recording duty of 10% and the second ink having a recording duty of 100%. The recording medium was a polyethylene terephthalate (PET) film (product name "Ultra-transparent PET film GIY-0305", manufactured by Lintec, 30 msec after the start of contact in the Bristow method). 1 / 2 Water absorption up to 0mL / m 2 More than 10mL / m 2 In Example 67, however, a highly transparent polyvinyl chloride (product name "3M Scotchcal Clear Graphic Film IJ8150", manufactured by 3M, 30 msec after the start of contact in the Bristow method) was used. 1 / 2 Water absorption up to 0mL / m 2 More than 10mL / m 2In Comparative Examples 7 and 8, a wood-free paper (product name "55PW8KCOC", manufactured by Lintec, 30 msec after the start of contact in the Bristow method) was used. 1 / 2 Water absorption rate up to 12 mL / m 2 ) was used. In addition, except for Comparative Example 5, recording was performed in the order of the first reaction liquid, the first ink, the second reaction liquid, and the second ink, and in Comparative Example 5, recording was performed in the order of the first reaction liquid, the second reaction liquid, the first ink, and the second ink.

[0154] In Example 2, instead of the inkjet recording device described above, the reaction liquid and the first ink shown in Table 11 were filled in the storage units communicating with the reaction liquid applying device 1201 and the ink applying device 1202 of the inkjet recording device 100 configured as shown in FIG. 3. The reaction liquid and the second ink shown in Table 11 were filled in the storage units communicating with the reaction liquid applying device 5201 and the ink applying device 5202 of the inkjet recording device 100 configured as shown in FIG. 3. Using the inkjet recording device 100, a 5 cm×5 cm solid image was recorded on a recording medium, with the recording duty of the first reaction liquid being 10% and the recording duty of the first ink being 100%. The conveying speed of the conveying member 1300 was adjusted so that the time difference between the application of the reaction liquid and the application of the ink was 500 milliseconds. Five seconds after the first reaction liquid was applied, a 5 cm x 5 cm solid image was printed so as to overlap the solid image, with the second reaction liquid having a printing duty of 10% and the second ink having a printing duty of 100%. In the present invention, in the evaluation criteria for each item below, "AA", "A" and "B" were defined as acceptable levels, and "C" was defined as an unacceptable level. The evaluation conditions and evaluation results are shown in Tables 11 and 12. In this embodiment, the application of ink and reaction liquid to a unit area is performed by one or more relative scans of the print head and print medium, so the number of relative scans is listed in the "Number of print passes" column in Tables 11 and 12.

[0155] (Prevents the second ink from sinking) [In the case of the second ink containing pigment] Regarding the obtained image, if the second ink is an ink containing carbon black, its lightness L * If the second ink contains a pigment other than carbon black, its chroma C * was measured. * , and C * The color difference was measured by the color difference display method specified by CIE using a fluorescence spectrodensitometer (product name "FD-7", manufactured by Konica Minolta). In order to equalize the conditions during the measurement, a highly transparent PVC (product name "3M Scotchcal Clear Graphic Film IJ8150", manufactured by 3M) was placed under the recording medium on which the image was recorded. The L * Or C * was measured. * Or C * The difference between the values ​​was calculated, and the suppression of the second ink from sinking was evaluated according to the following evaluation criteria. AA:L * Or C * The difference was 3 or less A:L * Or C * The difference was more than 3 and less than 5. B:L * Or C * The difference was more than 5 and less than 10. C:L * Or C * The difference was more than 10.

[0156] [In the case of the second ink that does not contain pigment] A friction test was conducted using an abrasion resistance tester (manufactured by Tester Sangyo), which is a friction tester II (Gakushin type) conforming to JIS L0849, and a white friction cloth (cotton) as specified in JIS L0803, by rubbing the surface of the recorded image back and forth 150 times with a load of 500g. The image after the friction test was visually inspected, and the suppression of embedding of the second ink was evaluated according to the evaluation criteria shown below. The absence of scratches on the image after the back and forth movement means that the second ink is not embedded and is present on top of the layer of the first ink. AA: No scratches were observed on the image after 150 strokes A: Scratch marks were observed on the image after 150 strokes, but no scratches were observed on the image after 100 strokes. B: Scratch marks were observed on the image after 100 strokes, but no scratches were observed on the image after 50 strokes. C: Scratch marks were observed on the image after 50 strokes.

[0157] (Adhesion) The image was left to stand in an environment at a temperature of 25° C. for 1 hour. Then, cellophane tape (product name "Cellotape (registered trademark)", width 15 mm, manufactured by Nichiban) was attached to the surface of the image in a length of 3 cm. The tape was peeled off at an angle of 120 degrees from the attachment direction at a speed of 2 cm / s, and peeling of the image was visually confirmed, and the fixation of the image was evaluated according to the following evaluation criteria. A: The image did not stick to the tape and did not peel off. B: Part of the image was attached to the tape, but the underlying layer of the recording medium was not visible in the peeled area. C: Part of the image was attached to the tape, and the underlying layer of the recording medium was visible in the peeled off area.

[0158] [Table 11]

[0159] [Table 12]

Claims

1. An inkjet recording method comprising: ejecting a first ink, a second ink, a first reaction liquid, and a second reaction liquid from a recording head to record an image on a recording medium in which the first ink, the second ink, the first reaction liquid, and the second reaction liquid overlap in at least a partial area, the method comprising: a first reaction liquid applying step of applying the first reaction liquid to a recording medium; a first ink applying step of applying the first ink to an area to which the first reaction liquid is to be applied; a second reaction liquid applying step of applying the second reaction liquid to a recording medium; a second ink applying step of applying the second ink to the region to which the second reaction liquid is applied, the first ink is a water-based ink containing a pigment, the second ink is an aqueous ink containing at least one particulate material selected from the group consisting of pigments and resin particles, the first reactive liquid and the second reactive liquid are each an aqueous reactive liquid containing a reactive agent that reacts with ink, the reactant of the first reaction solution contains a water-soluble cationic resin, The viscosity of a mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink in a ratio of 7:100 (mass ratio) is higher than the viscosity of a mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink in a ratio of 7:100 (mass ratio), and a viscosity of a mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink in a ratio of 7:100 (mass ratio) is higher than a viscosity of a mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink in a ratio of 7:100 (mass ratio); 30 msec from the start of contact of the recording medium in the Bristow method １／２ Water absorption up to 10 mL / m ２ An inkjet recording method, comprising the steps of:

2. 2. The ink jet recording method according to claim 1, wherein the cationic resin in the first reaction liquid is a resin having a quaternary ammonium salt structure.

3. The inkjet recording method according to claim 1 , wherein the reactant of the second reaction liquid contains a water-soluble cationic resin.

4. 2. The ink jet recording method according to claim 1, wherein the second reaction liquid has a higher surface tension than the first reaction liquid.

5. 2. The ink jet recording method according to claim 1, wherein the pigment of the first ink is titanium oxide.

6. 2. The inkjet recording method according to claim 1, wherein a viscosity of the mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink in a mass ratio of 7:100 is at least twice as high as a viscosity of the mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink in a mass ratio of 7:

100.

7. The inkjet recording method according to claim 3 , wherein a content (% by mass) of the cationic resin in the first reaction liquid is greater than a content (% by mass) of the cationic resin in the second reaction liquid.

8. 2. The ink jet recording method according to claim 1, wherein the reactant of the first reaction liquid contains at least one selected from the group consisting of polyvalent metal salts and organic acids.

9. The inkjet recording method according to claim 1 , wherein a content (% by mass) of the reactant in the first reaction liquid is greater than a content (% by mass) of the reactant in the second reaction liquid.

10. The ink jet recording method according to claim 1 , wherein the first ink further contains a water-soluble resin.

11. The second ink further contains a water-soluble resin, The inkjet recording method according to claim 10, wherein an acid value of the water-soluble resin in the first ink is higher than an acid value of the water-soluble resin in the second ink.

12. 2. The ink jet recording method according to claim 1, wherein the first ink is a white ink and the second ink is a color ink.

13. 2. The ink jet recording method according to claim 1, wherein the first ink is a white ink, and the second ink is a clear ink that does not contain a pigment.

14. 2. The inkjet recording method according to claim 1, wherein the application of the first ink and the second ink, and the application of the first reaction liquid and the second reaction liquid to a unit area of ​​the recording medium are each performed by a plurality of relative scans of the recording head and the recording medium.

15. applying the first ink and the second ink, and the first reaction liquid and the second reaction liquid to a unit area of ​​the recording medium, respectively, by one relative scan of the recording head and the recording medium; 2. The inkjet recording method according to claim 1, wherein the time difference between application of the first ink and the second reaction liquid to the unit area is 5 seconds or more.

16. an inkjet recording apparatus used for ejecting a first ink, a second ink, a first reaction liquid, and a second reaction liquid from a recording head, and recording an image on a recording medium in which the first ink, the second ink, the first reaction liquid, and the second reaction liquid are overlapped in at least a partial area, the inkjet recording apparatus comprising: a first reaction liquid applying means for applying the first reaction liquid to a recording medium; a first ink applying means for applying the first ink to an area to which the first reaction liquid is applied; A second reaction liquid applying means for applying the second reaction liquid to a recording medium; a second ink applying means for applying the second ink to an area to which the second reaction liquid is applied, the first ink is a water-based ink containing a pigment, the second ink is an aqueous ink containing at least one particulate material selected from the group consisting of pigments and resin particles, the first reactive liquid and the second reactive liquid are each an aqueous reactive liquid containing a reactive agent that reacts with ink, the reactant of the first reaction solution contains a water-soluble cationic resin, The viscosity of a mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink in a ratio of 7:100 (mass ratio) is higher than the viscosity of a mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink in a ratio of 7:100 (mass ratio), and a viscosity of a mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink in a ratio of 7:100 (mass ratio) is higher than a viscosity of a mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink in a ratio of 7:100 (mass ratio); 30 msec from the start of contact of the recording medium in the Bristow method １／２ Water absorption up to 10 mL / m ２ 1. An inkjet recording apparatus comprising:

17. A set of an aqueous ink and an aqueous reaction liquid for use in an inkjet recording method in which a first ink, a second ink, a first reaction liquid, and a second reaction liquid are ejected from a recording head to record an image on a recording medium in which the first ink, the second ink, the first reaction liquid, and the second reaction liquid are overlapped in at least a partial area, the set comprising: the inkjet recording method includes a first reaction liquid applying step of applying the first reaction liquid to a recording medium; a first ink applying step of applying the first ink to an area to which the first reaction liquid is to be applied; a second reaction liquid applying step of applying the second reaction liquid to a recording medium; a second ink applying step of applying the second ink to the region to which the second reaction liquid is applied, the first ink is a water-based ink containing a pigment, the second ink is an aqueous ink containing at least one particulate material selected from the group consisting of pigments and resin particles, the first reactive liquid and the second reactive liquid are each an aqueous reactive liquid containing a reactive agent that reacts with ink, the reactant of the first reaction solution contains a water-soluble cationic resin, The viscosity of a mixed liquid 1-1 obtained by mixing the first reaction liquid and the first ink in a ratio of 7:100 (mass ratio) is higher than the viscosity of a mixed liquid 2-1 obtained by mixing the second reaction liquid and the first ink in a ratio of 7:100 (mass ratio), and a viscosity of a mixed liquid 1-2 obtained by mixing the first reaction liquid and the second ink in a ratio of 7:100 (mass ratio) is higher than a viscosity of a mixed liquid 2-2 obtained by mixing the second reaction liquid and the second ink in a ratio of 7:100 (mass ratio); 30 msec from the start of contact of the recording medium in the Bristow method １／２ Water absorption up to 10 mL / m ２ A set of an aqueous ink and an aqueous reaction liquid, characterized in that:

Images