Inkjet recording method, inkjet recording device, and liquid composition

Abstract

To provide an inkjet recording method excellent in continuous discharge stability, and intermittent discharge stability, and capable of accurately detecting a state of a liquid composition including ink.SOLUTION: An inkjet recording method for recording an image on a recording medium includes: using an inkjet recording device provided with a liquid discharging head for discharging a liquid composition, and a detector for detecting a state of the liquid composition. The liquid composition contains a material such as a coloring material, and a nonionic surface active agent, the conductivity of the liquid composition is 10 μS / cm or higher, the liquid discharging head has a circulation passage for circulating the liquid composition through a liquid chamber, the detector detects a state of the liquid composition by electrical conduction between a pair of electrodes, and a discharge element substrate includes a first protective layer for blocking the contact of a heater for liquid discharge with the liquid composition, a second protective layer formed with a metal material, and means for applying a voltage to the second protective layer.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In recent years, inkjet recording methods have made it possible to record high-definition, highly colored images, similar to those achieved by silver halide photography and offset printing, and the demands on ink reliability have become stricter. Methods for ejecting ink from a recording head include a method using mechanical energy and a method using thermal energy. In the case of a thermal method in which ink is ejected from a recording head by the action of thermal energy, the heater for ejecting ink from the recording head becomes hot. Furthermore, the heater is subjected to a combination of physical effects, such as impacts caused by cavitation due to the foaming of ink and the contraction of bubbles, and chemical effects caused by the ink. To protect the heater from these effects, a protective layer is provided on the heater portion.

[0003] When ink is repeatedly ejected, the components in the ink heated to high temperatures change into a substance that is poorly soluble or poorly dispersible, known as "kogane," and this "kogane" adheres to the surface of the protective layer. When kogane adheres to and accumulates on the surface of the protective layer, the thermal energy generated by the ejection heater is not sufficiently transmitted to the ink, and the thermal energy imparted to the ink is reduced, which can affect the ejection properties. The deterioration of the ink ejection properties causes image unevenness.

[0004] Various measures have been proposed to suppress the deterioration of ejection performance due to the adhesion of kogation. For example, a recording head has been proposed in which the surface layer (upper protective layer) of the protective layer is made of a metal such as iridium, and this upper protective layer is used as an electrode to cause an electrochemical reaction, dissolving the upper protective layer and removing the accumulated kogation (Patent Document 1). In addition, a recording head has been proposed in which the protective layer is charged to the same polarity as the components in the ink that can become kogation, thereby performing voltage control to generate electrical repulsion and suppressing the adhesion of substances that cause kogation (Patent Document 2).

[0005] In addition, the liquid components in the ink evaporate from the nozzles of the recording head, and the ink near the nozzles may become thicker and more viscous. Such thickening of the ink may reduce the ink droplet ejection speed, and the ink application position may deviate from the intended position. In particular, when the pause time before the next ink droplet is ejected is long or when the ink contains a large amount of solids, the ink thickening due to the evaporation of the liquid components becomes significant. In order to suppress such thickening of the ink, a recording head has been proposed in which a circulation flow path through which the ink circulates is provided near the ejection element (Patent Document 3). However, in the case of the recording head proposed in Patent Document 3, if the connection to the device is not properly performed at the connection part of the ink supply path, a large amount of ink may leak out in a short time. For this reason, an inkjet recording device has been proposed that can quickly detect the occurrence of ink leakage by measuring the resistance value of a detection means composed of a pair of electrode pins provided at the connection part of the ink supply flow path (Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-105364 A [Patent Document 2] JP 2009-051146 A [Patent Document 3] Patent Publication No. 2022-065137 [Patent Document 4] JP 2019-177594 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have conducted a study to achieve both continuous ejection stability and intermittent ejection stability. Specifically, an image was recorded on a recording medium using an inkjet recording device equipped with a recording head having the protective layer proposed in Patent Document 2, the circulation flow path proposed in Patent Document 3, and the detection means (a pair of electrode pins) proposed in Patent Document 4. As a result, it was found that a new problem occurred, such as the accuracy of detecting liquid leakage decreasing over time.

[0008] It is therefore an object of the present invention to provide an inkjet recording method which is excellent in continuous ejection stability and intermittent ejection stability and which is capable of detecting the state of a liquid composition such as ink with high accuracy. It is also an object of the present invention to provide an inkjet recording apparatus and a liquid composition for use 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 recording an image on a recording medium using an inkjet recording apparatus including an aqueous liquid composition, a container for containing the liquid composition, a liquid ejection head for ejecting the liquid composition supplied from the container via a supply system, and a detector for detecting a state of the liquid composition, the liquid composition containing (1) a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group selected from the group consisting of a colorant, a resin, and a reactant, and (2) a nonionic surfactant, the liquid composition having a conductivity of 10 μS / cm or more, the liquid ejection head including a discharge element substrate having a discharge port for ejecting the liquid composition and including a liquid chamber filled therein, and a discharge element substrate including a discharge port for discharging the liquid composition and including a liquid chamber filled therein, the liquid composition being supplied from the container to the liquid ejection head via the liquid chamber, and a circulation flow path through which the liquid composition circulates, and the detector detects a state of the liquid composition by electrical conduction between a pair of electrodes arranged in the supply system, and the ejection element substrate comprises: a heater for liquid ejection arranged in a flow path through which the liquid composition flows, the flow path being connected to the ejection port; a first protective layer arranged at a position in the flow path corresponding to the heater, for blocking contact between the heater and the liquid composition in the flow path; a second protective layer made of a metal material arranged at a position corresponding to the heater in the flow path and in contact with the liquid composition; and a voltage application means for applying a voltage such that the second protective layer becomes an electrode charged with the same polarity as the material, and a portion electrically connected via the liquid composition becomes an electrode charged with a polarity opposite to that of the material. Effect of the Invention

[0010] According to the present invention, it is possible to provide an inkjet recording method that is excellent in continuous ejection stability and intermittent ejection stability and is capable of detecting the state of a liquid composition such as ink with high accuracy. Furthermore, according to the present invention, it is possible to provide an inkjet recording apparatus and a liquid composition used in the inkjet recording method. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of an inkjet recording apparatus of the present invention. [Diagram 2] FIG. 2 is a perspective view illustrating an example of a recording head. [Diagram 3] FIG. 2 is a cross-sectional perspective view showing an example of a discharge element substrate. [Figure 4] FIG. 2 is a plan view showing a schematic view of the vicinity of a heater for liquid ejection of the ejection element substrate. [Diagram 5] 5 is a cross-sectional view that shows a schematic diagram of the ejection element substrate cut vertically along the XY line in FIG. 4. [Figure 6] FIG. 4 is a schematic diagram showing an example of a voltage control procedure. [Figure 7] FIG. 2 is a schematic diagram showing an example of a liquid composition supply system. [Figure 8] FIG. 13 is a schematic diagram showing another example of the heating unit. [Figure 9] 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 liquid composition dissociated into ions, but for convenience, it is expressed as "containing a salt". Aqueous liquid compositions for inkjet (ink, reaction liquid, etc.) may be simply referred to as "liquid composition", "ink" and "reaction liquid". Physical property values ​​are values ​​at room temperature (25°C) and normal pressure (1 atm) unless otherwise specified.

[0013] As mentioned above, the present inventors have studied an inkjet recording device equipped with a recording head having the protective layer proposed in Patent Document 2, the circulation flow path proposed in Patent Document 3, and the detection means (a pair of electrode pins) proposed in Patent Document 4. As a result, they have found that after ejecting ink for a long period of time, a new problem arises in that the accuracy of detecting conditions such as ink leakage and remaining amount decreases over time. The present inventors speculate as follows about the reason why such a problem arises when using an inkjet recording device having the above configuration.

[0014] The detection means proposed in Patent Document 4 includes detection pins (a pair of electrode pins) for detecting ink leakage. In this detection means, a predetermined voltage is applied to two electrode pins inserted into a joint where ink supplied from a storage unit flows into a recording head, and the potential difference between the electrode pins is measured to detect the presence or absence of ink leakage. A liquid composition such as ink usually contains an electrolyte consisting of a cation and an anion. In particular, water-based ink is easy to conduct electricity in the presence of an electrolyte because the relative dielectric constant of water is high. Therefore, when a voltage is applied to the electrode pins while the ink leaked at the connection unit is in contact with the two electrode pins, a current flows between the electrode pins via the ink. On the other hand, when the ink is not in contact with the electrode pins (not leaking), there is no path for the current to flow between the electrode pins, and no current flows. The inventors of the present invention have studied and found that when the conductivity of the ink is 10 μS / cm or more, a current flows reliably between the electrodes, making it easy to detect the state of the ink. However, it was found that even if the conductivity of the ink is 10 μS / cm or more, the detection accuracy decreases over time when using a recording head having the protective layer proposed in Patent Document 2 and the circulation flow path proposed in Patent Document 3. The inventors speculate that the reason for this is as follows.

[0015] The protective layer proposed in Patent Document 2 is made of a metal material, and when ink is ejected, a voltage is applied to the protective layer, polarizing the protective layer and the electrode disposed opposite the protective layer. That is, when a voltage is applied, the protective layer becomes a cathode or an anode, and the electrode disposed opposite the protective layer becomes an anode or a cathode. When the protective layer is a cathode, cations in the ink adhere to the protective layer by electrostatic attraction, and anions adhere to the electrode disposed opposite the protective layer. When an ejection operation is performed, the ink near the heater for ejecting liquid and the ejection port is ejected from the ejection port to the outside of the recording head. As a result, the cations attached to the protective layer of the heater are ejected outside the recording head together with the ink.

[0016] On the other hand, in the circulation flow path proposed in Patent Document 3, ink circulates through the position corresponding to the heater, so that ink containing cations is constantly supplied to the vicinity of the heater. Therefore, even if cations are discharged outside the recording head by the discharge operation, the cations in the ink that is continuously supplied adhere to the protective layer of the heater, which serves as the cathode. As a result, cations are discharged outside the recording head again by the discharge operation, but cations are still supplied to the vicinity of the heater via the circulation flow path. By repeating such a cycle, the concentration of electrolytes in the ink gradually decreases, and the conductivity of the ink falls below 10 μS / cm, which is thought to cause the detection accuracy to decrease over time.

[0017] As a result of further investigation, the present inventors have found that by using a liquid composition such as an ink containing a nonionic surfactant, the detection accuracy of the state of the liquid composition can be maintained for a long period of time, even when a recording head having a specific protective layer and a circulation flow path is used. Hereinafter, the mechanism by which the effect of maintaining the detection accuracy of the state of the liquid composition for a long period of time by using a liquid composition containing a nonionic surfactant will be described.

[0018] When a metal material and a surfactant coexist, the surfactant is coordinated to the metal material with the hydrophilic portion facing the metal material side and the hydrophobic portion facing the opposite side of the metal material. It is presumed that the surfactant is coordinated to the metal material in this manner because free electrons are exchanged between the metal material and the hydrophilic portion of the surfactant. Therefore, when a protective layer formed of a metal material and a surfactant coexist, it is considered that the surfactant is coordinated to the protective layer with the hydrophilic portion facing the protective layer side and the hydrophobic portion facing the opposite side of the protective layer. Furthermore, since no voltage is applied to the protective layer and the electrodes disposed opposite to each other before ejection, it is considered that cations and anions are not supplied and the surfactant is mainly coordinated to the protective layer.

[0019] When an anionic surfactant is used, the surfactant coordinated to the protective layer and the electrode disposed opposite to it is released by electrostatic repulsion when a voltage is applied to the protective layer. In contrast, when a nonionic surfactant is used, the surfactant is not released even when a voltage is applied to the protective layer because it is electrically neutral, and remains in the vicinity of the heater. Therefore, the protective layer and the electrode disposed opposite to it are kept covered with the nonionic surfactant, and the adhesion of cations and anions to the cathode and anode is suppressed, making it difficult for these ions to be ejected outside the recording head. This maintains the concentration of electrolytes in the liquid composition at a constant level, and it is believed that the detection accuracy is maintained for a long period of time.

[0020] <Inkjet recording method, inkjet recording apparatus, and liquid composition> The inkjet recording method of the present invention (hereinafter, simply referred to as "recording method") is an inkjet recording method for recording an image on a recording medium using an inkjet recording device. The inkjet recording device includes an aqueous liquid composition, a container for containing the liquid composition, a liquid ejection head for ejecting the liquid composition supplied from the container through a supply system, and a detector for detecting the state of the liquid composition. The liquid composition contains (1) a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group selected from the group consisting of a coloring material, a resin, and a reactant, and (2) a nonionic surfactant. The liquid composition has a conductivity of 10 μS / cm or more. The liquid ejection head includes a discharge element substrate having a discharge port for ejecting the liquid composition and including a liquid chamber filled with the liquid composition, and a circulation flow path through which the liquid composition circulates between the container and the liquid ejection head via the liquid chamber. The detector detects the state of the liquid composition by electrical conduction between a pair of electrodes arranged in the supply system. The ejection element substrate includes a heater for ejecting liquid, a first protective layer, a second protective layer, and a means for applying a voltage (voltage application means). The heater is a member disposed in a flow path through which the liquid composition flows, which is connected to the ejection port. The first protective layer is a portion disposed in a position corresponding to the heater in the flow path, and blocks contact between the heater and the liquid composition in the flow path. The second protective layer is a portion formed of a metal material, disposed in a position corresponding to the heater in the flow path and in contact with the liquid composition. The voltage application means is a means for applying a voltage so that the second protective layer becomes an electrode charged with the same polarity as the material (the "material (1)" in the liquid composition) and the portion electrically connected via the liquid composition becomes an electrode charged with a polarity opposite to that of the material.

[0021] The inkjet recording apparatus (hereinafter, also simply referred to as "recording apparatus") of the present invention includes an aqueous liquid composition, a storage unit that stores the liquid composition, a liquid ejection head that ejects the liquid composition supplied from the storage unit through a supply system, and a detector that detects the state of the liquid composition. The liquid composition contains (1) a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group selected from the group consisting of a colorant, a resin, and a reactant, and (2) a nonionic surfactant. The liquid composition has a conductivity of 10 μS / cm or more. The liquid ejection head includes an ejection element substrate having an ejection port for ejecting the liquid composition and including a liquid chamber filled with the liquid composition, and a circulation flow path through which the liquid composition circulates between the storage unit and the liquid ejection head via the liquid chamber. The detector detects the state of the liquid composition by electrical conduction between a pair of electrodes arranged in the supply system. The ejection element substrate includes a heater for ejecting liquid, a first protective layer, a second protective layer, and a means for applying a voltage (voltage application means). The heater is a member that is connected to the discharge port and is disposed in a flow path through which the liquid composition flows. The first protective layer is a part that is disposed in a position corresponding to the heater in the flow path and blocks contact between the heater and the liquid composition in the flow path. The second protective layer is a part that is disposed in a position corresponding to the heater in the flow path and in contact with the liquid composition and is made of a metal material. The voltage application means is a means for applying a voltage so that the second protective layer becomes an electrode that is charged with the same polarity as the material (the "material (1)" in the liquid composition) and so that the part that is conductive via the liquid composition becomes an electrode that is charged with a polarity opposite to that of the material.

[0022] The liquid composition of the present invention is a composition used in an inkjet recording method for recording an image on a recording medium using an inkjet recording device. The inkjet recording device includes an aqueous liquid composition, a container for containing the liquid composition, a liquid ejection head for ejecting the liquid composition supplied from the container through a supply system, and a detector for detecting the state of the liquid composition. The liquid composition of the present invention contains (1) a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group selected from the group consisting of a colorant, a resin, and a reactant, and (2) a nonionic surfactant. The liquid composition of the present invention has a conductivity of 10 μS / cm or more. The liquid ejection head includes an ejection element substrate having an ejection port for ejecting the liquid composition and including a liquid chamber filled with the liquid composition, and a circulation flow path through which the liquid composition circulates between the container and the liquid ejection head via the liquid chamber. The detector detects the state of the liquid composition by electrical conduction between a pair of electrodes arranged in the supply system. The ejection element substrate includes a heater for ejecting the liquid, a first protective layer, a second protective layer, and a means for applying a voltage (voltage application means). The heater is a member that is connected to the discharge port and is disposed in a flow path through which the liquid composition flows. The first protective layer is a part that is disposed in a position corresponding to the heater in the flow path and blocks contact between the heater and the liquid composition in the flow path. The second protective layer is a part that is disposed in a position corresponding to the heater in the flow path and in contact with the liquid composition and is made of a metal material. The voltage application means is a means for applying a voltage so that the second protective layer becomes an electrode that is charged with the same polarity as the material (the "material (1)" in the liquid composition) and so that the part that is conductive via the liquid composition becomes an electrode that is charged with a polarity opposite to that of the material.

[0023] (Inkjet recording device) The inkjet recording apparatus will be described in detail below with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of the inkjet recording apparatus of the present invention. The inkjet recording apparatus of this embodiment is an inkjet recording apparatus that records an image on a recording medium using ink and a reaction liquid containing a reactant that reacts with the ink. The X direction, Y direction, and Z direction respectively indicate the width direction (total length direction), depth direction, and height direction of the inkjet recording apparatus. The recording medium is transported in the X direction.

[0024] The inkjet recording apparatus 100 of the embodiment shown in FIG. 1 is configured to include a recording unit 1000, a heating unit 2000, a fixing unit 3000, a cooling unit 4000, an inverting unit 5000, and a paper discharge unit 6000. In the recording unit 1000, various liquids are applied by a liquid application unit 1200 to a recording medium 1100 conveyed from a paper feeder 1400 by a conveying member 1300. In the heating unit 2000, the liquid applied to the recording medium 1100 is heated by a heating unit 2100, and volatile components such as water in the liquid are evaporated and dried. In the fixing unit 3000, a fixing member 3100 is brought into contact with the area of ​​the recording medium 1100 to which the liquid has been applied, and heated to promote fixing of the image to the recording medium 1100. The recording medium 1100 is then cooled by a cooling member 4100 of the cooling unit 4000. When an image is to be recorded on the back side following the front side (recording surface), the recording medium 1100 is first inverted by an inversion device 5100 of an inversion section 5000. Next, an image is recorded on the back side in the same manner as the front side, and then the recording medium is transported by a transport member 6100 of a paper discharge section 6000 and stacked and stored in a recording medium storage section 6200.

[0025] Any recording medium may be used as the recording medium 1100. For example, recording media having ink absorbency (permeability) such as recording media without a coating layer, such as plain paper, uncoated paper, and synthetic paper, and recording media with a coating layer, such as printing paper, glossy paper, and art paper, may be used. In addition, recording media having no permeability, such as films or sheets made of resin materials such as polyvinyl chloride (PVC) and polyethylene terephthalate (PET), may be used. The basis weight (g / m2) of the recording medium 1100 may be determined by the following formula: 2 ) is 30g / m2 More than 500g / m 2 It is preferable that the thickness is less than 50 g / m 2 More than 450g / m 2 It is even more preferable that:

[0026] [Recording Section] The recording unit 1000 includes a liquid applying device 1200. The liquid applying device 1200 includes a reaction liquid applying device 1201 and an ink applying device 1202. The reaction liquid applying device 1201 shown in FIG. 1 is an example of a unit using an inkjet type ejection head. In addition, the reaction liquid applying device may be configured using a gravure coater, an offset coater, a die coater, a blade coater, or the like. The reaction liquid may be applied by the reaction liquid applying device 1201 either before or after the ink application as long as it can come into contact with the ink on the recording medium 1100. However, in order to record high-quality images on various recording media having different liquid absorption characteristics, it is preferable to apply the reaction liquid before the ink is applied. An inkjet type ejection head (recording head) is used as the ink applying device 1202. The ejection method of the ejection head as the liquid applying device 1200 can be exemplified by a method of ejecting liquid by generating film boiling in the liquid by an electrothermal converter to form bubbles, and a method of ejecting liquid by an electromechanical converter.

[0027] The liquid deposition device 1200 is a line head extending in the Y direction, and has ejection ports arranged in a range that covers an image recording area of ​​the widest usable recording medium. The ejection head has an ejection port surface 1207 (FIG. 3) on which ejection ports are formed on its lower side (the recording medium 1100 side), and the ejection port surface faces the recording medium 1100 at a very small distance of about a few millimeters.

[0028] 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 the "liquid composition" or "liquid." Furthermore, the "liquid ejection head" may be referred to as the "recording head."

[0029] Fig. 2 is a perspective view showing an example of a liquid applying device. The liquid applying device 1200 shown in Fig. 2 is a line head, in which a plurality of ejection element substrates 1203, each having an ejection port array, are arranged in a straight line. A plurality of ejection port arrays are arranged on the ejection element substrate 1203. Ink is supplied to the liquid applying device 1200 from an ink storage section (a subtank to be described later) via a connection section (inflow section) 1507 in Fig. 7.

[0030] FIG. 3 is a cross-sectional perspective view showing an example of a discharge element substrate. The discharge element substrate 1203 shown in FIG. 3 includes a discharge port forming member 1206 having a discharge port 1204 opened therein, and a substrate 1205 having discharge elements (not shown) disposed thereon. The discharge port forming member 1206 and the substrate 1205 are laminated to form a first flow path 1208 and a second flow path 1209 through which liquid flows. The first flow path 1208 is a region from an inlet 1212 through which liquid flows in from an inflow path 1210 to a portion between the discharge port 1204 and the discharge element (FIG. 7, liquid chamber 1508). The second flow path 1209 is a region from a portion between the discharge port 1204 and the discharge element (FIG. 7, 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. 3). The liquid that has passed through the inlet 1210 and the inlet 1212 enters the first flow path 1208. Then, the liquid that has passed through the portion between the outlet 1204 and the ejection element (liquid chamber 1508 in FIG. 7) flows through the second flow path 1209 and the outlet 1213 to the outlet path 1211.

[0031] [Ejection element board] FIG. 4 is a plan view showing the vicinity of a heater for liquid ejection of the ejection element substrate. FIG. 5 is a cross-sectional view showing the ejection element substrate cut vertically along the XY line in FIG. 4. The ejection element substrate 101 is composed of a silicon base 102, a heat storage layer 103, a heating resistor layer 104, and an electric wiring layer 105. The heat storage layer 103 is made of materials such as a thermally oxidized silicon film, a silicon oxide film, and a silicon nitride film. The electric wiring layer 105 is a wiring made of a metal material such as aluminum, aluminum-silicon, and aluminum-copper. The heating portion 104a as a heater (electrothermal conversion element) is formed by removing a part of the electric wiring layer 105 to form a gap and exposing the heating resistor layer 104 at that part. The electric wiring layer 105 is connected to a driving element circuit (not shown) or an external power supply terminal (not shown) and receives power from the outside. In the illustrated example, the electric wiring layer 105 is disposed as a layer adjacent to the heating resistor layer 104. However, the present invention is not limited to this configuration. The electrical wiring layer 105 may be formed as a layer adjacent to the silicon substrate 102 or the heat storage layer 103, a part of which may be partially removed as a gap, and the heating resistor layer 104 may be disposed therein.

[0032] The first protective layer 106 is made of a material such as silicon oxide and silicon nitride, and is provided adjacent to the heat generating portion 104a and the electrical wiring layer 105 with the electrical wiring layer 105 partially interposed therebetween. The first protective layer 106 also functions as an insulating layer that blocks contact between the heat generating portion 104a and the liquid composition in the flow channel.

[0033] The second protective layer 107 is the outermost layer that comes into contact with the liquid composition in the flow path. The region of the second protective layer 107 that is located on the flow path side of the heat generating portion 104a and that applies the heat generated by the heat generating portion 104a to the liquid composition corresponds to the heater 108 for discharging liquid. The second protective layer 107 protects the heater 108 from chemical shocks and physical shocks (cavitation) that occur with the heat generated by the heat generating portion 104a, and also functions as an electrode. In order to achieve both of these characteristics, the second protective layer 107 is made of a metal material.

[0034] It is preferable that the protective layer is strong against physical effects such as impacts due to cavitation and chemical effects due to the liquid composition. For this reason, it is preferable to use a metal material containing at least one metal element selected from the group consisting of iridium, ruthenium, and tantalum as the material constituting the protective layer. Examples of such metal materials include these metal elements and alloys of these metal elements with other metals. In the case of alloys, the higher the ratio of the above metal elements, the stronger the protective layer is likely to be against physical and chemical effects. It is preferable to use iridium, ruthenium, or tantalum rather than alloys. Since it is difficult to form a strong oxide film even when heated and the potential can be generated more uniformly, it is particularly preferable to use iridium or ruthenium from the viewpoint of easily removing components having ionic groups attached to the electrode, and therefore the continuous ejection stability can be further improved. In addition, the surface of the second protective layer is heated to about 300°C or more and 600°C or less by the heat generated by the heater 108, but it is more preferable to use iridium because iridium does not form an oxide film up to 800°C even in the atmosphere, which is a condition in which oxygen is more abundant than in the liquid composition.

[0035] For the second protective layer 107, at least one metal element selected from the group consisting of iridium, ruthenium, and tantalum, or a metal material containing these metal elements can be used. In particular, the metal material forming the second protective layer 107 is preferably at least one selected from the group consisting of iridium and ruthenium. However, such metal materials have poor adhesion. For this reason, an adhesion layer 109 is disposed between the first protective layer 106 and the second protective layer 107 to improve the adhesion of the second protective layer 107 to the first protective layer 106. The adhesion layer 109 is formed from a material having electrical conductivity.

[0036] The second protective layer 107 is inserted into the through-hole 110 and electrically connected to the electrical wiring layer 105 via the adhesive layer 109. The electrical wiring layer 105 extends to the end of the ejection element substrate 101, and its tip becomes an external electrode 111 for electrical connection to the outside. A flow path forming member 112 is joined to the ejection element substrate 101 having the above-mentioned configuration. The flow path forming member 112 has an ejection port 113 at a position corresponding to the heater 108, and forms a flow path that communicates with the ejection port 113 from a supply port (not shown) provided through the ejection element substrate 101, via the heater 108.

[0037] A method of controlling the voltage in the above-mentioned recording head will be described. The second protective layer 107 is composed of two regions, a region (heater side region 107a) including the heater 108 formed at a position corresponding to the heat generating portion 104a, and the other region (counter electrode side region 107b), and each region is electrically connected. When no liquid is present in the flow path, no electrical connection is made between the heater side region 107a and the counter electrode side region 107b. However, the liquid such as the liquid composition contains electrolytes as components having anionic groups, components having cationic groups, and components having ionic groups such as soluble metal ions. Therefore, when the flow path is filled with liquid, the heater side region 107a and the counter electrode side region 107b as a region conducting through the liquid composition are conducting through the liquid.

[0038] When voltage control is performed, between the heater side region and the counter electrode side region, scorching and its causative substances are likely to adhere to the heater side region that is heated during ejection. This is because the dispersibility of particles becomes unstable and the aggregation and precipitation of low solubility materials occur due to temperature increase and pressure increase. Since coloring materials, resins, reactants, and the like among the components of the liquid composition are likely to be causative substances of scorching, it is preferable to apply a voltage to the heater side so that it is charged with a polarity opposite to the polarity of the components such as coloring materials, resins, and reactants. For example, when a liquid containing an anionic component such as a coloring material having an anionic group is used, a voltage is applied so that the heater side is the cathode and the counter electrode side is the anode. Also, when a liquid containing a cationic component such as a polyvalent metal or a cationic resin is used, a voltage is applied so that the heater side is the anode and the counter electrode side is the cathode.

[0039] When a liquid composition containing an anionic component is used, a potential difference is generated between the heater side region 107a as a cathode and the counter electrode side region 107b as an anode when electricity is applied. The component having an anionic group is electrically repelled by the heater side region 107a, and the soluble metal ions are electrically repelled by the counter electrode side region 107b, respectively, so that the distribution state of each component changes according to the charging state of each electrode. Since the heater side region 107a is negatively charged, the component having an anionic group moves away from the vicinity of the heater 108 due to electrical repulsion, and is less likely to adhere to the heater, and the decrease in ejection performance is suppressed. Since the counter electrode side region 107b is positively charged, the component having an anionic group moves in a direction approaching it, and some of them temporarily adhere to the counter electrode side region 107b. However, the component having an anionic group can be removed by soluble metal ions that may be present in the vicinity. In addition, when a liquid composition containing a cationic component is used, a potential difference occurs between the heater side region 107a as an anode and the counter electrode side region 107b as a cathode when electricity is applied. Components having cationic groups can be removed by the same mechanism as when a liquid composition containing an anionic component is used, except that the charged state is reversed. In this way, the behavior of the heater side region 107a and the counter electrode side region 107b works together to suppress the adhesion of kogation and the deterioration of ejection performance when the voltage of the recording head is controlled.

[0040] [Voltage control procedure] The procedure for performing voltage control will be described. FIG. 6 is a schematic diagram showing an example of the procedure for voltage control. When the recording device receives image data, the image data is developed as data suitable for the recording device (step S1). Next, a potential difference is generated between the heater side area 107a and the counter electrode side area 107b of the second protective layer 107 in the recording head 100 (step S2). At this time, a voltage is applied from the voltage application means of the recording device through the ejection element substrate 101 of the recording head 100, with the heater side area 107a of the second protective layer 107 as a cathode and the counter electrode side area 107b as an anode. Thereafter, recording is started by ejecting liquid (step S3). After the recording is completed (step S4), the application of the voltage between the heater side area 107a and the counter electrode side area 107b of the second protective layer 107 is stopped, and the potential difference generated between them is released (step S5). In this embodiment, the printing operation by ejecting liquid includes not only the period during which the print head is ejecting liquid to perform printing, but also the period from when a print start command is received to when the ejection of liquid ends.

[0041] The voltage control is performed to suppress the adhesion of substances that cause scorching to the heater for liquid ejection. Therefore, it is preferable to continuously perform the voltage control from a certain time before to a certain time after the timing of the liquid ejection operation based on the recording data and the preliminary ejection data. In this case, the period during which the voltage control is continued may be appropriately set in consideration of the power consumption, etc. The voltage Eb (V) applied to the second protective layer when ejecting the liquid from the liquid ejection head is preferably less than 2.5V from the viewpoint of ejection stability during continuous recording. When controlling by applying a voltage of less than 2.5V, the amount of hydrogen ions generated is small because electrolysis of water is unlikely to occur. This reduces the amount of precipitation of components having ionic groups, and the occurrence of scorching can be further suppressed. The voltage Eb (V) may be considered as an absolute value, but in the examples described later, the voltage Eb (V) is shown as the potential difference between the second protective layer and the counter electrode.

[0042] When the heater side region 107a of the second protective layer 107 is used as a cathode and the counter electrode side region 107b is used as an anode, a voltage may be applied and controlled so that these electrodes have the above-mentioned cathode and anode relationship (FIG. 5). Methods for controlling by applying a voltage include the following methods (1) to (3). Among them, method (1) is preferable. When the heater side region 107a is used as an anode and the counter electrode side region 107b is used as a cathode, a voltage opposite to the above may be applied. (1) A method in which the heater side region 107a is used as a ground and a positive potential is applied to the counter electrode side region 107b. (2) A method in which a negative potential is applied to the heater side region 107a and the counter electrode side region 107b is grounded. (3) A method of applying a potential to both the heater side region 107a and the counter electrode side region 107b.

[0043] [Supply system] In the recording method of the present invention, an inkjet recording device is used that includes a liquid ejection head having a discharge element substrate including a liquid chamber filled with a liquid composition, and a circulation flow path in which the liquid composition circulates from a storage unit to the liquid ejection head via the liquid chamber. FIG. 7 is a schematic diagram showing an example of a supply system for a liquid such as ink. A supply unit 1500 of a liquid application device 1200 shown in FIG. 7 includes 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 that 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 application device 1200 by discharging (discharging) the liquid from the discharge port for image recording, suction recovery, and the like. The refill pump 1506 transfers the liquid corresponding to the consumed amount from the main tank 1504 to the sub-tank 1503.

[0044] 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.

[0045] The negative pressure control unit 1509 includes two pressure adjustment mechanisms with mutually different control pressures set. 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, respectively, 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, as well as inflow channels 1210 and outflow channels 1211 that communicate with the liquid chamber 1508, which is a portion between the ejection port 1204 (FIG. 3) and the ejection element (not shown). Since the inlet channel 1210 and the outlet channel 1211 are respectively connected to the common inlet channel 1514 and the common outlet channel 1515, a flow (arrow in FIG. 7) occurs in which a part of the liquid flows from the common inlet channel 1514 through the inside of the liquid chamber 1508 to the common outlet channel 1515. The arrow in FIG. 3 indicates the flow of the liquid inside the liquid chamber 1508. That is, as shown in FIG. 3, the liquid in the first flow channel 1208 flows to the second flow channel 1209 through between the ejection port 1204 and the ejection element.

[0046] In the ejection element substrate 1203, in addition to a flow path A in which part of the liquid flows from the common inflow path 1514 via the liquid chamber 1508 into the common outflow path 1515, there is also a flow path B in which part of the liquid flows through the common outflow path 1515 without passing through the liquid chamber 1508. The liquid that joins in the common outflow path 1515 flows out from a connection part (outflow part) 1507 to the outside of the liquid deposition device 1200.

[0047] In order to stably eject the liquid, it is necessary to suppress the change in physical properties, such as the increase in viscosity of the liquid composition caused by the evaporation of the liquid components from the ejection port and the precipitation of non-volatile components (solids). In order to suppress such a change in physical properties, it is effective to increase the flow rate of the liquid. When the flow rate of the liquid is increased, the evaporation ratio of the liquid components in the liquid composition can be reduced. The ejection element substrate 1203 has a flow path B in addition to the flow path A, so that the flow rate of the liquid can be increased. Also, if the amount of the liquid components evaporated from the ejection port is large, the physical properties of the liquid are likely to change in the outflow path 1211, and the non-volatile components (solids) are likely to precipitate. In response to this, by providing a flow path B in which a part of the liquid flows in the common outflow path 1515 without passing through the liquid chamber 1508, the liquid that has passed through the liquid chamber 1508 and the liquid that has not passed through the liquid chamber 1508 can be merged in the common outflow path 1515. This makes it possible to suppress the increase in viscosity of the liquid and the change in physical properties, such as the precipitation of non-volatile components (solids).

[0048] 7, 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. This also causes a pressure difference between an inlet 1212 (FIG. 3) communicating with the inflow channel 1210 and an outlet 1213 (FIG. 3) communicating with the outflow channel 1211. When the liquid is caused to flow by the pressure difference between the inlet 1212 and the outlet 1213, it is preferable to control the circulation flow rate (mm / s) of the liquid composition flowing through the circulation channel to 0.1 mm / s or more from the viewpoint of further improving the detection accuracy. By setting the flow rate of the liquid composition to 0.1 mm / s or more, even if a part of the nonionic surfactant is discharged outside the system, another nonionic surfactant will quickly adhere to the heater for discharging the liquid, maintaining the ion concentration in the liquid, and it is considered that the detection accuracy will be further improved. When the liquid composition is caused to flow by the pressure difference between the inlet 1212 and the outlet 1213, it is preferable to control the circulation flow rate (mm / s) of the liquid composition flowing through the circulation flow path to 10.0 mm / s or less.

[0049] The negative pressure control unit 1509 has a function of maintaining the pressure in the liquid chamber 1508 at a preset constant pressure even if the flow rate of the liquid composition in the liquid chamber 1508 fluctuates due to the difference in the discharge amount of each discharge port 1204 (FIG. 3). The two pressure adjustment mechanisms constituting the negative pressure control unit 1509 may be any mechanism capable of controlling the pressure downstream of the negative pressure control unit 1509 within a certain range centered on a desired set value. For example, a mechanism similar to a so-called "pressure reducing regulator" can be cited as such a pressure adjustment mechanism. By providing such a pressure adjustment mechanism, it is possible to prevent the backflow of liquid in the liquid chamber 1508. When recording based on the recording data, the discharge amount of the liquid differs for each discharge port. By providing a pressure adjustment mechanism, it is possible to generate a uniform flow of liquid even in discharge ports that are not discharging liquid and in their flow paths, so that it is possible to suppress changes in physical properties such as an increase in the viscosity of the liquid and precipitation of solids. In addition, it is preferable to adjust the temperature of the liquid flowing through the liquid deposition device 1200 to a range of 15°C or higher and 50°C or lower, and more preferably 30°C or higher and 45°C or lower, in order to maintain constant physical properties of the liquid and enable stable ejection.

[0050] [Detector] In the recording method of the present invention, an inkjet recording device equipped with a detector for detecting the state of the liquid composition is used. This detector is a system that detects the state of the liquid composition, such as the presence or absence of leakage of the liquid composition in the supply path and the remaining amount of the liquid composition in the container, by electrical conduction between a pair of electrodes arranged in the supply system. The detector is arranged, for example, at any position in the supply system of the liquid composition shown in FIG. 7.

[0051] A method for detecting leakage of the liquid composition will be described. As a detector for detecting leakage of the liquid composition, a pair of electrode pins 214a and 214b provided at the connection part (inlet part) 1507 and a control board (not shown) connected thereto are used. The presence or absence of leakage of the liquid composition is detected by applying a voltage so that a current flows from the electrode pin 214a to the electrode pin 214b, and measuring the potential difference (resistance value) between them. When the liquid composition is leaking, a current flows between the pair of electrode pins 214a and 214b through a component having an ionic group, which is an electrolyte in the liquid composition. At this time, the potential on the electrode pin 214b side is lower than that on the electrode pin 214a side, and therefore the presence or absence of leakage of the liquid composition can be detected by detecting the potential difference between them using a detection means (not shown). That is, when a potential difference is detected, it is determined that the liquid composition is leaking at the connection part (inlet part) 1507.

[0052] A method for detecting the remaining amount of the liquid composition will be described. As a detector for detecting the remaining amount of the liquid composition, a pair of electrode pins 213a and 213b provided in the subtank 1503 and a control board (not shown) connected thereto are used. When the liquid composition is consumed, the remaining amount is detected by applying a voltage so that a current flows from the electrode pin 213a to the electrode pin 213b, and measuring the potential difference (resistance value) between them. When the remaining amount of the liquid composition is less than a certain value, no conduction occurs through the component having an ionic group, which is an electrolyte in the liquid composition, so that the potential difference is not detected. Conversely, when the remaining amount of the liquid composition is equal to or greater than a certain value, a current flows between the pair of electrode pins 213a and 213b through the component having an ionic group, which is an electrolyte in the liquid composition. At this time, the potential on the electrode pin 213b side is lower than that on the electrode pin 213a side, so that the remaining amount of the liquid composition is determined to be equal to or greater than a certain value by detecting the potential difference between them using a detection means (not shown).

[0053] When the voltage applied to the electrode pins is increased, the potential difference becomes easier to detect, and the detection accuracy is improved. Therefore, the voltage Ea (V) applied to the electrodes when the detector detects the state of the liquid composition is preferably 2.5 V or more. Ea (V) is more preferably 2.5 V or more and 5.0 V or less, and particularly preferably 2.5 V or more and 4.0 V or less. The voltage applied to the electrodes (electrode pins 214a and 214b) when the detector detects the state of the liquid composition is defined as "Ea (V)", and the voltage applied to the second protective layer 107 (FIG. 5) when the liquid ejection head ejects the liquid composition is defined as "Eb (V)". In this case, it is preferable to satisfy the relationship Eb<2.5≦Ea. If the voltage Ea (V) is less than 2.5 V, the detection accuracy may be slightly decreased. If the voltage Eb (V) is 2.5 V or more, the continuous ejection stability may be slightly decreased. That is, by satisfying the relationship Eb<2.5≦Ea, it is possible to further improve the detection accuracy and the continuous ejection stability. The absolute value of Eb(V) is preferably 0.0V or more and less than 2.5V.

[0054] [Transport system] As shown in FIG. 1, the recording unit 1000 is configured to include a liquid applying device 1200 and a conveying member 1300 that conveys the recording medium 1100. The liquid applying device 1200 applies a reaction liquid and ink to a desired position of the recording medium 1100 conveyed by the conveying member 1300. Each liquid applying device receives an image signal of recording data and applies the necessary reaction liquid and ink to each position. FIG. 1 shows the conveying member 1300 in the form of a conveying belt, but a spur, a conveying drum, or the like may be used as long as it has the function of conveying the recording medium 1100. In order to improve the conveying accuracy, a material that can fix the recording medium 1100 can be used as the conveying member 1300. Specifically, a method of providing a hole in the conveying member 1300 and fixing the recording medium 1100 by sucking from the back side, a method of forming the conveying member 1300 from an appropriate material and fixing the recording medium 1100 by electrostatic adsorption, etc. can be mentioned.

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

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

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

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

[0059] Fig. 8 is a schematic diagram showing another example of the heating section. Here, the difference from the heating section shown in Fig. 1 and described above will be described. The heating section 2000 shown in Fig. 8 includes a first heating device 2101 and a second heating device 2102, and a first conveying member 2201 and a second conveying member 2202 arranged opposite the first heating device 2101 and the second heating device 2102, respectively.

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

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

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

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

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

[0065] When a liquid such as a reaction liquid or 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 liquid, the resin particles soften and are easily formed into a film, and the scratch resistance of the image can be improved. When a liquid such as a reaction liquid or 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, and the scratch resistance of the image can be improved.

[0066] The nip pressure of the fixing member 3100 and the conveying member 3200, i.e., the pressure applied to the recording medium when passing 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 100 Pa. The time required for the recording medium to pass through the contact-type heating and pressing mechanism (nip time) is preferably from 0.25 seconds to 5.0 seconds, more preferably from 0.5 seconds to 4.0 seconds, and particularly preferably from 1.0 seconds to 3.0 seconds.

[0067] FIG. 9 is a schematic diagram showing another example of the fixing unit. Here, the difference from the fixing unit shown in FIG. 1 and described above will be described. The fixing unit 3000 shown in FIG. 9 is a contact type heating and pressurizing mechanism including a plurality of fixing rollers 3101 and a plurality of conveying members 3201 arranged opposite to these fixing rollers 3101. An image is fixed on the recording medium 1100 to which a liquid such as ink has been applied by passing between the fixing rollers 3101 and the conveying members 3201. The degree of image fixing on the recording medium can be adjusted by controlling the number of fixing rollers 3101 and the conveying members 3201, the nip time of the recording medium by these, the temperature, the pressure, and the like.

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

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

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

[0071] <Liquid composition> The aqueous liquid composition used in the recording method of the present invention is an inkjet composition containing (1) a material selected from the group consisting of a coloring material, a resin, and a reactant, which can be dissolved or dispersed in the liquid composition by the action of an ionic group, and (2) a nonionic surfactant. Specific examples of the liquid composition include a "reaction liquid" containing a reactant that reacts with the ink, and an "ink" containing a coloring material and a resin. The ink may be a clear ink that does not substantially contain a coloring material. Although the reaction liquid and the clear ink are liquid compositions that do not substantially contain a coloring material, it is possible to record an image using only the reaction liquid or the clear ink without using an ink containing a coloring material, depending on the type of recording medium. Of course, an image can also be recorded using a liquid composition that does not substantially contain a coloring material (reaction liquid or clear ink) in combination with a liquid composition (ink) containing a coloring material.

[0072] (conductivity) The electrical conductivity of the liquid composition is 10 μS / cm or more. Since even a small amount of leakage of the liquid composition can be detected, the electrical conductivity of the liquid composition is preferably 100 μS / cm or more. There is no particular upper limit to the electrical conductivity of the liquid composition, and it may be, for example, 3,000 μS / cm or less.

[0073] The electrical conductivity of the liquid composition can be measured using a general-purpose electrical conductivity meter. The electrical conductivity of the liquid composition can be controlled, for example, by adjusting the type and content of ionic components in the liquid composition.

[0074] (Surfactant) The liquid composition contains a nonionic surfactant. The nonionic surfactant is preferably a hydrocarbon-based nonionic surfactant. Examples of the hydrocarbon-based nonionic surfactant include polyoxyethylene alkyl ether, ethylene oxide adduct of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymer.

[0075] The liquid composition may further contain various surfactants. Examples of the surfactants include hydrocarbon surfactants, fluorine surfactants, and silicone surfactants. These surfactants may be any of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0076] The content (mass %) of the surfactant, including the nonionic surfactant, in the liquid composition is preferably 0.1 mass % or more and 5.0 mass % or less, and more preferably 0.2 mass % or more and 1.5 mass % or less, based on the total mass of the liquid composition.

[0077] (Reaction solution) The recording method of the present invention preferably includes a reaction liquid application step of applying an aqueous reaction liquid containing a reactant that reacts with the aqueous ink to a recording medium. The reaction liquid containing a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group can be used as the liquid composition described above. Each component used in the reaction liquid will be described in detail below.

[0078] [Reactants] The reaction liquid reacts with the ink when it comes into contact with the ink, and aggregates the components in the ink (components having anionic groups, such as resins, surfactants, and self-dispersing pigments), and contains a reactant. The presence of the reactant can destabilize the state of the components having anionic groups in the ink when the ink and the reactant come into contact with each other on the recording medium, and promote the aggregation of the ink. Examples of the reactant include cationic components such as polyvalent metal ions and cationic resins, and organic acids. The reactant may be used alone or in combination of two or more.

[0079] Examples of polyvalent metal ions constituting polyvalent metal salts include Ca. 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Sr 2+ , B.A. 2+ , and Zn2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ , and Al 3+ In order to add a polyvalent metal ion to the reaction solution, a water-soluble polyvalent metal salt (which may be a hydrate) formed by combining a polyvalent metal ion with an anion can be used. Examples of the anion include Cl. - , Br - , I - , ClO - , ClO2 - , ClO3 - , ClO4 - , NO2 - , NO3 - , SO4 2- , CO3 2- , HCO3 - , PO4 3- , HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO - ), CH3COO - , CH3CH(OH)COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2, and CH3SO3 - In the case where a polyvalent metal ion is used as a reactant, the content (mass%) of the polyvalent metal salt in the reaction solution is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction solution. In this specification, when the polyvalent metal salt is a hydrate, the "content (mass%) of the polyvalent metal salt" in the reaction solution means the "content (mass%) of the anhydride of the polyvalent metal salt" excluding water as the hydrate.

[0080] The reaction liquid containing an organic acid has a buffering ability in the acidic range (less than pH 7.0, preferably pH 2.0 to 5.0), and thus efficiently converts the anionic groups of the components present in the ink into an acid form and causes them to aggregate. Examples of the organic acid include monocarboxylic acids and salts thereof, such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and salts and hydrogen salts thereof, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and salts and hydrogen salts thereof, such as citric acid and trimellitic acid; and tetracarboxylic acids and salts and hydrogen salts thereof, such as pyromellitic acid. When an organic acid is used as the reactant, the content (mass %) of the organic acid in the reaction liquid is preferably 1.0 mass % or more and 50.0 mass % or less based on the total mass of the reaction liquid.

[0081] Examples of cationic resins include resins having a structure of primary to tertiary amines and resins having a structure of quaternary ammonium salts. Specific examples include resins having a structure of vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensate. In order to increase the solubility in the reaction solution, the cationic resin may be used in combination with an acidic compound or the cationic resin may be subjected to a quaternary treatment. When a cationic resin is used as a reactant, the content (mass%) of the cationic resin in the reaction solution is preferably 0.1 mass% or more and 10.0 mass% or less based on the total mass of the reaction solution.

[0082] The reactant is preferably a polyvalent metal ion. By using a reaction solution containing a polyvalent metal ion as a reactant, the continuous ejection stability can be further improved. Compared with organic acids and cationic resins, the anions of water-soluble polyvalent metal salts, which can generate polyvalent metal ions by ionic dissociation, are less likely to corrode metals. For this reason, it is believed that the use of a reaction solution containing a polyvalent metal ion as a reactant makes the electrodes less likely to wear even with long-term and continuous use, improving the continuous ejection stability.

[0083] [Aqueous medium] The reaction liquid is an aqueous reaction liquid containing at least water as an aqueous medium. The aqueous medium used in the reaction liquid can be the same as the aqueous medium that can be contained in the ink described later. The aqueous medium used in the reaction liquid can contain the water-soluble organic solvent that can be contained in the ink described later. The content (mass%) of the water-soluble organic solvent in the reaction liquid is preferably 1.0 mass% or more and 45.0 mass% or less based on the total mass of the reaction liquid. The water-soluble organic solvent preferably contains a specific water-soluble hydrocarbon compound described later. The content (mass%) of the water-soluble hydrocarbon compound in the reaction liquid is preferably 1.0 mass% or more and 20.0 mass% or less based on the total mass of the reaction liquid. In addition, the content (mass%) of water in the reaction liquid is preferably 50.0 mass% or more and 95.0 mass% or less based on the total mass of the reaction liquid.

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

[0085] [Physical properties of reaction solution] The reaction liquid is an aqueous reaction liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the reaction liquid at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the reaction liquid at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the reaction liquid at 25°C is preferably 5.0 or more and 9.5 or less, and more preferably 6.0 or more and 9.0 or less.

[0086] (ink) The recording method of the present invention includes, for example, an ink application step of applying an aqueous inkjet ink to a recording medium to record an image. An ink containing a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group can be used as the liquid composition described above. The ink does not need to be cured by active energy rays such as ultraviolet rays or electron beams, and therefore does not need to contain a monomer that polymerizes when irradiated with active energy rays. Each component used in the ink will be described in detail below.

[0087] [Colorant] The ink preferably contains a coloring material. Pigments or dyes can be used as the coloring material. The content (mass %) of the coloring material in the ink is preferably 0.5% by mass or more and 15.0% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

[0088] 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.

[0089] 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.

[0090] As the resin dispersant for dispersing the pigment in the aqueous medium, it is preferable to use one that can disperse the pigment in the aqueous medium by the action of anionic groups. As the resin dispersant, a resin having an anionic group can be used, and it is preferable to use a resin as described below, especially a water-soluble resin. The content (mass%) of the pigment in the ink is preferably 0.3 times or more and 10.0 times or less in mass ratio to the content (mass%) of the resin dispersant.

[0091] 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.

[0092] It is preferable to use a dye having an anionic group. Specific examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, and anthrapyridone dyes. The dye may be used alone or in combination of two or more.

[0093] The coloring material is preferably at least one selected from the group consisting of self-dispersed pigments having an anionic group and resin-dispersed pigments dispersed with a resin dispersant having an anionic group. By using an ink containing such a self-dispersed pigment or resin-dispersed pigment as a coloring material, the continuous ejection stability can be further improved. Unlike dyes, which are coloring materials that exist in a dissolved state, pigments that are not dissolved in the ink have a low probability of contacting the heater of the recording head and have excellent liquid contact properties. For this reason, it is considered that the use of an ink containing such a self-dispersed pigment or resin-dispersed pigment as a coloring material makes the electrodes less likely to wear out even with long-term and continuous use, improving the continuous ejection stability.

[0094] [resin] The ink can contain a resin. By using an ink containing a resin, an image with improved abrasion resistance can be recorded. The resin can be added to the ink (i) to stabilize the dispersion state of the pigment, that is, as a resin dispersant or its auxiliary, or (ii) to improve various properties of the recorded image.

[0095] The content (mass %) of the resin in the ink is preferably 0.1% by mass or more and 20.0% by mass or less, more preferably 0.5% by mass or more and 15.0% by mass or less, based on the total mass of the ink. Examples of the form of the resin include block copolymers, random copolymers, graft copolymers, and combinations thereof. The resin may be 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.

[0096] The resin is preferably at least one selected from the group consisting of resin particles formed of a resin having an anionic group and resin particles dispersed with a dispersant. By using an ink containing these resin particles, the intermittent ejection stability can be further improved. Resin particles present in the ink in a particulate state have a small contact area with the water-soluble organic solvent in the ink, so they are unlikely to form a gel-like substance. For this reason, by using an ink containing such resin particles, the ink is unlikely to thicken even if the liquid components evaporate, and it is considered that the intermittent ejection stability is improved.

[0097] [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.

[0098] 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 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 of styrene and α-methylstyrene is preferred. These resins are easily interacted with pigments, and therefore can be suitably used as a resin dispersant for dispersing pigments.

[0099] 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.

[0100] 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.

[0101] [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.

[0102] 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.

[0103] The acid value of the resin constituting the resin particles is preferably 5 mgKOH / g or more and 100 mgKOH / g or less. The weight average molecular weight of the resin constituting the resin particles is preferably 1,000 or more and 3,000,000 or less, and more preferably 100,000 or more and 3,000,000 or less. The volume-based cumulative 50% particle diameter (D 50) is preferably 50 nm or more and 500 nm or less. The volume-based cumulative 50% particle diameter of the resin particles is the diameter of the particles that is 50% of the total volume of the measured particles when integrated from the small particle diameter side in a particle diameter integration curve. The volume-based cumulative 50% particle diameter of the resin particles can be measured using the dynamic light scattering particle size analyzer and measurement conditions described above. The glass transition temperature of the resin particles is preferably 40° C. or more and 120° C. or less, and more preferably 50° C. or more and 100° C. or less. The glass transition temperature (° C.) of the resin particles can be measured using a differential scanning calorimeter (DSC). The resin particles do not need to contain a coloring material.

[0104] [Wax particles] The ink may contain particles formed of wax (wax particles). By using an ink containing wax particles, an image with improved abrasion resistance can be recorded. In this specification, the wax may be a composition containing components other than wax, or the wax itself. The wax particles may be dispersed by a dispersant such as a surfactant or a resin. The wax may be used alone or in combination of two or more kinds. The content (mass %) of the wax particles in the ink is preferably 0.1 mass % or more and 10.0 mass % or less, and more preferably 1.0 mass % or more and 5.0 mass % or less, based on the total mass of the ink.

[0105] In the narrow sense, wax is an ester of a water-insoluble higher monohydric or dihydric alcohol and a fatty acid, and includes animal waxes and vegetable waxes, but does not include oils and fats. In the broad sense, wax includes high melting point fats, mineral waxes, petroleum waxes, and blends and modified products of various waxes. In the present invention, any wax in the broad sense can be used without particular restrictions. Wax in the broad sense can be classified into natural waxes, synthetic waxes, blends thereof (blended waxes), and modified products thereof (modified waxes).

[0106] 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.

[0107] 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.

[0108] [Aqueous medium] The ink used in the recording method of the present invention is an aqueous ink containing at least water as an aqueous medium. The ink can contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water or ion-exchanged water is preferably used. The content (mass%) of water in the aqueous ink is preferably 50.0 mass% or more and 95.0 mass% or less based on the total mass of the ink. In addition, the content (mass%) of the water-soluble organic solvent in the aqueous ink is preferably 2.0 mass% or more and 40.0 mass% or less based on the total mass of the ink. As the water-soluble organic solvent, any of those usable for inkjet inks, such as alcohols, (poly)alkylene glycols, glycol ethers, nitrogen-containing solvents, and sulfur-containing solvents, can be used. The water-soluble organic solvent may be used alone or in combination of two or more.

[0109] [Water-soluble hydrocarbon compounds] The water-soluble organic solvent contained in the ink preferably contains a specific water-soluble hydrocarbon compound. This water-soluble hydrocarbon compound is a compound having a hydrocarbon chain having three or more carbon atoms substituted with two or more hydrophilic groups selected from the group consisting of hydroxyl groups, amino groups, and anionic groups. However, the hydrocarbon chain may be interrupted by a sulfonyl group or an ether group. When the hydrocarbon chain has three or four carbon atoms, the hydrophilic group contains an anionic group, or the hydrocarbon chain is interrupted by a sulfonyl group.

[0110] In the present invention, a hydrocarbon compound that is dissolved in water at 25°C at the content of the compound in the ink is considered to be "water-soluble". In other words, the solubility in water at 25°C is greater than the content in the ink. The fact that the hydrocarbon chain is interrupted by a sulfonyl group or an ether group means that a sulfonyl group (-S(=O)2-) or an ether group (-O-) is present in the middle of the hydrocarbon chain. Water-soluble hydrocarbon compounds have hydrogen-bonding groups such as hydroxyl groups, amino groups, anionic groups, sulfonyl groups, and ether groups. Therefore, by using an ink containing this hydrocarbon compound, cockling and curling of a recording medium on which an image is recorded can be suppressed. General hydrocarbon compounds having a hydrocarbon chain with a relatively small number of carbon atoms (3 or 4) tend to have a small molecular weight and a low vapor pressure. However, since the above water-soluble hydrocarbon compounds have anionic groups of hydrogen bonds or the hydrocarbon chain is interrupted by a sulfonyl group, they are difficult to evaporate due to inter- or intra-molecular interactions, and remain between fibers to suppress cockling and curling. The content (mass %) of the water-soluble hydrocarbon compound in the ink is preferably 1.0 mass % or more and 20.0 mass % or less based on the total mass of the ink.

[0111] The number of carbon atoms in the hydrocarbon chain constituting the water-soluble hydrocarbon compound is preferably from 3 to 50, and more preferably from 3 to 10. Examples of the anionic group include a sulfonic acid group and a carboxylic acid group. Specific examples of water-soluble hydrocarbon compounds include alkanediols such as 1,5-pentanediol and 1,6-hexanediol; amino acids such as alanine, β-alanine, trimethylglycine, amidosulfuric acid (also known as sulfamic acid), aminomethanesulfonic acid, taurine (also known as 2-aminoethanesulfonic acid), carbamic acid, glycine, aspartic acid, glutamic acid, sulfanilic acid, or salts of the above-mentioned acids, phenylalanine, leucine, isoleucine, threonine, tryptophan, valine, methionine, lysine, and arginine; sulfonyl compounds such as bis(2-hydroxyethyl)sulfone; alkylene glycols such as triethylene glycol, tetraethylene glycol, tripropylene glycol, and polyethylene glycols having a number average molecular weight of about 200 to 1,000; and sugars such as sorbitol, D-sorbitol, xylitol, trehalose, fructose, and D(+)-xylose. The water-soluble hydrocarbon compounds may be used alone or in combination of two or more.

[0112] [Other ingredients] The ink may contain various other components as necessary. Examples of other components include various additives such as defoamers, surfactants, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors. However, it is preferable that the ink does not contain a reactant to be contained in the reaction liquid.

[0113] [Ink properties] The ink is a water-based ink applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the ink at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the ink at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the ink at 25°C is preferably 7.0 or more and 9.5 or less, and more preferably 8.0 or more and 9.5 or less. EXAMPLES

[0114] 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 present invention. "Parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified.

[0115] <Preparation of pigment dispersion> (Pigment dispersion 1) A solution obtained by dissolving 5.0 g of concentrated hydrochloric acid in 5.5 g of water was cooled to 5°C, and in this state, 1.8 g of 4-amino-1,2-benzenedicarboxylic acid was added. The container containing this solution was placed in an ice bath, and while stirring to maintain the temperature of the solution at 10°C or less, a solution obtained by dissolving 1.8 g of sodium nitrite in 9.0 g of 5°C ion-exchanged water was added. After stirring for 15 minutes, carbon black (BET specific surface area 254 m 2 6.0 g of ethanol (1.0 g / g, DBP oil absorption 180 mL / 100 g) was added under stirring, and further stirred for 15 minutes to obtain a slurry. The obtained slurry was filtered with filter paper (product name "Standard Filter Paper No. 2", Advantec), and the particles were thoroughly washed with water and dried in an oven at 110°C. An appropriate amount of ion-exchanged water was added to adjust the pigment (carbon black) content, and Pigment Dispersion 1 with a pigment content of 10.0% was obtained. The obtained Pigment Dispersion 1 contained a self-dispersing pigment in which -C6H3-(COONa)2 groups were bonded to the pigment (carbon black) particle surface.

[0116] (Pigment dispersion 2) A styrene-ethyl acrylate-acrylic acid copolymer (resin 1) with an acid value of 150 mgKOH / g and a weight average molecular weight of 8,000 was prepared. 20.0 parts of resin 1 were neutralized with potassium hydroxide in an amount equimolar to the acid value, and an appropriate amount of pure water was added to prepare an aqueous solution of resin 1 with a resin (solid content) content of 20.0%. 10.0 parts of pigment (carbon black), 15.0 parts of the aqueous solution of resin 1, and 75.0 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 2 with a pigment content of 10.0% and a resin dispersant (resin 1) content of 3.0%.

[0117] (Pigment dispersion 3) Pigment dispersion 3 was prepared using the same procedure as for pigment dispersion 2 described above, except that the pigment was changed to CI Pigment Blue 15:3. The pigment content was 10.0% and the resin dispersant (resin 1) content was 3.0%.

[0118] (Pigment Dispersion 4) Pigment dispersion 4 was prepared in the same manner as for pigment dispersion 2 described above, except that the pigment was changed to CI Pigment Red 122. The pigment content was 10.0% and the resin dispersant (resin 1) content was 3.0%.

[0119] (Pigment Dispersion 5) Pigment dispersion 5 was prepared in the same manner as in Pigment Dispersion 2 described above, except that the pigment was changed to CI Pigment Yellow 74. The pigment content was 10.0% and the resin dispersant (Resin 1) content was 3.0%.

[0120] (Pigment Dispersion 6) A mixture was obtained by mixing 30.0 parts of pigment, 4.0 parts of dispersant, 0.2 parts of defoamer (product name "Surfynol 104E", manufactured by Nissin Chemical Industry Co., Ltd.), and 70.8 parts of ion-exchanged water. As the dispersant, a nonionic surfactant (product name "NIKKOL BC-20", polyoxyethylene cetyl ether) was used. As the pigment, carbon black (product name "MCF#1000", manufactured by Mitsubishi Chemical Co., Ltd.) was used. The obtained mixture was placed in a paint shaker (manufactured by Toyo Seiki Co., Ltd.) filled with zirconia beads having a diameter of 0.3 mm, and dispersed for 60 minutes to obtain pigment dispersion 6 having a pigment content of 30.0% and a dispersant (surfactant) content of 4.0%.

[0121] <Preparation of dye aqueous solution> After dissolving the dye (CI Direct Blue 199) in pure water, excess acid was added to precipitate the dye. The precipitated dye was separated by filtration, and the dye with the anionic groups in the acid form was obtained as a wet cake. The obtained wet cake was added to pure water, and an aqueous solution of sodium hydroxide in an equimolar amount to the anionic groups of the dye was added to neutralize the anionic groups and dissolve the dye. An appropriate amount of pure water was further added to obtain dye aqueous solution 1 with a dye content of 10.0%.

[0122] <Preparation of resin particles> [Cumulative 50% particle size of resin particles based on volume] The aqueous dispersion of resin particles was diluted with pure water to prepare a liquid containing resin particles with a resin particle content of 1.0% as a measurement sample. A particle size distribution meter (product name "Nanotrac UPA-EX150", manufactured by Nikkiso) using dynamic light scattering was used to measure the volume-based cumulative 50% particle diameter (D50 (nm)) of the resin particles in the measurement sample. The measurement conditions were SetZero: 30 seconds, number of measurements: 3, measurement time: 180 seconds, shape: spherical, refractive index: 1.6.

[0123] [Glass transition temperature of resin particles] A resin sample was prepared by drying an aqueous dispersion of resin particles. A differential scanning calorimeter (trade name "Q200", manufactured by TA Instruments) was used to measure the glass transition temperature (Tg (℃)) of the resin particles by performing two temperature cycles in which the temperature was increased from -70℃ to 180℃ at a rate of 10℃ / min.

[0124] (Resin particles 1) A solution was prepared by mixing 0.2 parts of potassium persulfate and 74.0 parts of ion-exchanged water. An emulsion was prepared by mixing 19.0 parts of ethyl methacrylate, 5.0 parts of n-butyl methacrylate, 1.5 parts of methacrylic acid, and 0.3 parts of a reactive surfactant. A nonionic surfactant (trade name "ADEKA REASOAP ER20", manufactured by ADEKA, number of ethylene oxide groups: 20) was used as the reactive surfactant. The emulsion was dropped into the solution over 1 hour under a nitrogen atmosphere, polymerized while stirring at 80°C, and then stirred for another 2 hours. After cooling to room temperature, ion-exchanged water and an aqueous potassium hydroxide solution were added to obtain an aqueous dispersion of resin particles 1 with a content of resin particles 1 of 25.0%. The volume-based cumulative 50% particle diameter (D50) of resin particles 1 measured by the above-mentioned method was 100 nm, and the glass transition temperature (Tg) was 60°C.

[0125] (Resin particles 2) An aqueous dispersion of nonionic resin particles (product name "Vinyblan 1225", manufactured by Nissin Chemical Industry Co., Ltd., vinyl acetate-acrylic resin-based resin particles, resin particle content 45.0%) was diluted with ion-exchanged water to prepare an aqueous dispersion of resin particles 2 with a content of resin particles 2 of 25.0%. The volume-based cumulative 50% particle diameter (D50) of resin particles 2 was 100 nm, and the glass transition temperature (Tg) was 9°C.

[0126] <Preparation of Water-Soluble Resin> (Water-soluble resin 1) 20.0 parts of styrene-acrylic acid copolymer (water-soluble resin 1) synthesized by a conventional method was dissolved in ion-exchanged water using sodium hydroxide in an amount equivalent to the acid value to obtain an aqueous solution. The weight-average molecular weight of water-soluble resin 1 was 8,000, and the acid value was 120 mgKOH / g. The obtained aqueous solution was pressure-filtered with a microfilter (manufactured by Fujifilm) with a pore size of 3.0 μm. The resin content was adjusted by adding ion-exchanged water to obtain an aqueous solution of water-soluble resin 1 with a resin content of 20.0%.

[0127] (Water-soluble resin 2) A four-neck flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, and a reflux tube was prepared. 34.5 parts of isophorone diisocyanate and 49.8 parts of polypropylene glycol (number average molecular weight 2,000) were placed in this four-neck flask. Then, the mixture was reacted at 100°C for 2 hours under a nitrogen gas atmosphere. Next, 0.3 parts of ethylenediamine, 14.1 parts of dimethylolpropionic acid, and 150.0 parts of methyl ethyl ketone were added. Then, the residual rate of the isocyanate group was confirmed by FT-IR, and the mixture was reacted at 78°C until the desired residual rate was reached. Furthermore, 1.3 parts of methanol and 300.0 parts of ion-exchanged water were added to obtain a reaction liquid. The obtained reaction liquid was cooled to 40°C, and then ion-exchanged water was added, and a neutralizing agent (potassium hydroxide) was added while stirring at high speed with a homomixer. Methyl ethyl ketone was distilled off by heating and reducing pressure, and an aqueous solution of water-soluble resin 2 with a urethane resin (water-soluble resin 2) content of 20.0% was obtained. The weight average molecular weight of the water-soluble resin 2 was 12,000, and the acid value was 59 mgKOH / g.

[0128] <Preparation of Liquid Composition> The components (unit: %) shown in Tables 1-1 to 1-3 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 each liquid composition. In Tables 1-1 to 1-3, the numerical value attached to the polyethylene glycol indicates the number average molecular weight of the polyethylene glycol. Details of the product names in Tables 1-1 to 1-3 are shown below. In addition, the conductivity of the prepared liquid compositions at 25° C. was measured using a conductivity meter (product name "ES-51", manufactured by HORIBA). The measurement results are shown in Tables 1-1 to 1-3. PAA08: Cationic polymer, Nittobo Acetylenol E100: Nonionic surfactant (ethylene oxide adduct of acetylene glycol), manufactured by Kawaken Fine Chemicals NIKKOL BC-20: Nonionic surfactant (polyoxyethylene cetyl ether), manufactured by Nikko Chemicals, HLB value 17.0, carbon number 16 Pluronic(R) L31: Nonionic surfactant (triblock copolymer of ethylene oxide and propylene oxide), manufactured by ADEKA Silface SAG005: Nonionic surfactant (polyether modified siloxane compound), manufactured by Nissin Chemical Industry Co., Ltd.

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[0130] TIFF2025036182000002.tif198170

[0131] TIFF2025036182000003.tif199170

[0132] <Preparing the recording head> With reference to the description in Patent Document 2, liquid ejection heads 1 to 4 were manufactured as liquid application devices having the configuration shown in Fig. 2. As the constituent material of the second protective layer, iridium was used for liquid ejection heads 1 and 4, ruthenium for liquid ejection head 2, and tantalum for liquid ejection head 3. Then, the liquid ejection heads shown in Tables 2-1 and 2-2 were attached to an inkjet recording device having the configuration shown in Fig. 1, and liquid compositions 1 to 29 shown in Tables 2-1 and 2-2 were filled in the inkjet recording device.

[0133] In Examples 1 to 31, 36 and Comparative Examples 1 to 7, 9, and 10, voltage control was performed to charge the heater side region 107a of the second protective layer negatively and the counter electrode side region 107b positively (FIGS. 4 and 5). Specifically, a DC voltage corresponding to the absolute value of the voltage Eb (V) shown in Tables 2-1 and 2-2 was applied to the external electrode 111 connected to the heater side region 107a of the second protective layer (step S2). In Tables 2-1 and 2-2, the voltage Eb (V) column is shown as a numerical value with "+" to indicate the voltage applied to the external electrode, but the heater side region of the second protective layer is negatively charged. In Examples 32 to 35, voltage control was performed to charge the heater side region 107a of the second protective layer positively and the counter electrode side region 107b negatively. Specifically, a DC voltage corresponding to the absolute value of the voltage Eb (V) shown in Tables 2-1 and 2-2 was applied to the external electrode 111 connected to the heater side region 107a of the second protective layer (step S2). In Tables 2-1 and 2-2, the voltage Eb (V) column is shown as a numerical value with a "-" to indicate the voltage applied to the external electrode 111, and the heater side region 107a of the second protective layer is positively charged. In Comparative Examples 8, 11 to 13, no DC voltage was applied to the external electrodes 111 connected to the heater side region 107a and the counter electrode side region 107b.

[0134] As shown in Fig. 7, the recording heads 1 to 3 have a circulation flow path in which the liquid composition circulates from the subtank 1503 to the liquid application device 1200 (recording head) via a liquid chamber 1508. On the other hand, the recording head 4 does not have a circulation flow path via the liquid chamber 1508, and has only a circulation flow path in which the ink circulates between a connection part (inlet part) 1507 and a connection part (outlet part) 1507. In addition, for each recording head, the flow rate of the liquid composition in the circulation flow path was controlled by adjusting the pressure using a negative pressure control unit 1509 shown in Fig. 7.

[0135] <Detection Method> In carrying out the evaluation described below, the liquid composition was discharged while performing the detection described below (denoted as "leakage" and "remaining amount" in the target columns of Tables 2-1 and 2-2), and an image was recorded. In Examples 1 to 36 and Comparative Examples 1 to 6, 8, 9, and 12, the state of the liquid composition was detected using a pair of electrode pins. In Examples 1 to 14, 16 to 36, and Comparative Examples 1 to 6, 8, 9, and 12, a pair of electrode pins 214a and 214b provided at the connection part (inlet part) 1507 shown in FIG. 7 was used, and a control board connected to the electrode pins was operated. Then, a voltage Ea (V) shown in Tables 2-1 and 2-2 was applied to the electrode pin 214a, and leakage of the liquid composition was detected from the potential difference between the electrode pins. In Comparative Examples 7, 10, 11, and 13, the state of the liquid composition was detected using an optical sensor provided at the connection part (inlet part) of FIG. 7. In Example 15, a pair of electrode pins 213a and 213b provided in a subtank 1503 shown in Fig. 7 was used, and a control board connected to the electrode pins was operated. Then, a voltage Ea (V) shown in Tables 2-1 and 2-2 was applied to the electrode pin 213a, and the remaining amount of liquid composition was detected from the potential difference between the electrode pins.

[0136] <Evaluation> The following evaluations were carried out using an inkjet recording apparatus having the configuration shown in FIG. 2 The print duty of an image printed at 100% is defined as 100%. In the present invention, in the evaluation criteria shown below, "A" and "B" are acceptable levels, and "C" is an unacceptable level. The evaluation results are shown in Tables 2-1 and 2-2.

[0137] (Continuous discharge stability) An inkjet recording device equipped with a recording head of the type shown in Tables 2-1 and 2-2 was used, and a voltage for ejecting the liquid composition was applied to the heat generating portion 104a while maintaining a voltage controlled state (step S3 in FIG. 5 and FIG. 6). Specifically, a driving pulse having a voltage of 20.0 V, a pulse width of 1.5 μs, and a frequency of 0.5 kHz was applied to the heat generating portion 104a at 1.5×10 8 The liquid composition was discharged by applying the voltage 100 times. The discharge conditions were assumed to be such that, if the voltage was not controlled, scorching would occur on the heater for discharging the liquid.

[0138] After the above continuous ejection, solid images with a recording duty of 100% and 60% were recorded on glossy paper (product name "Canon Photo Paper Gloss Gold", manufactured by Canon). Since the liquid compositions used in Examples 13, 32 to 35 and Comparative Examples 1 and 5 did not contain a coloring material, similar solid images were recorded on an OHP film (product name "KOKUYO OHP Film VF-1420N", manufactured by KOKUYO) so that the recorded images could be easily confirmed. After the recording was completed (step S4), the voltage control was stopped (step S5). The state of unevenness in the recorded images was visually confirmed, and the continuous ejection stability was evaluated according to the following evaluation criteria. A: No unevenness was observed in any of the solid images. B: Irregularities were observed in a solid image with a print duty of 100%, but no unevenness occurred in a solid image with a print duty of 60%. C: Unevenness occurred in all solid images.

[0139] (Detection accuracy) After the evaluation of the continuous discharge stability described above, the ink in the device was used to simulate the suppression of deterioration of the detection accuracy over time in the following manner. Specifically, ink was extracted from the subtank 1503 and placed in a beaker. Then, a pair of electrode pins similar to those of 213a and 213b were immersed in the ink from the bottom to a predetermined length, electricity was applied, and whether a potential difference was detected was measured. The detection accuracy was evaluated by bringing the liquid composition into contact with the electrodes according to the conditions shown below. If the detection accuracy decreases, it becomes difficult to detect a potential difference even if the contact portion with the electrode pin is long, so if a potential difference is detected even if the immersion portion of the electrode pin is short, it means that the detection accuracy is excellent. Note that when the detection target is leakage of the liquid composition, if a potential difference is not detected despite leakage, it may be mistakenly determined that no leakage has occurred, so if the detection accuracy is excellent using the following method, leakage can be detected with high accuracy. A: A potential difference was detected even when the liquid composition was immersed to only 25% of the length from the bottom of the electrode pin. B: When the liquid composition was immersed to only 25% of the length from the bottom of the electrode pin, no potential difference was detected, but when the liquid composition was immersed to 50% of the length from the bottom of the electrode pin, a potential difference was detected. C: No potential difference was detected even when the liquid composition was immersed up to 50% of the length from the bottom of the electrode pin.

[0140] (Intermittent ejection stability) An inkjet recording device equipped with the types of recording heads shown in Tables 2-1 and 2-2 was used, and a driving pulse with a voltage of 20.0 V and a pulse width of 1.5 μsec was applied to the heat generating portion 104a at a frequency of 0.5 kHz to perform one ejection operation. After that, a predetermined rest time was provided, and a solid image was recorded on glossy paper (product name "Canon Photo Paper Gloss Gold", manufactured by Canon) with a recording duty of 100%. Since the liquid compositions used in Examples 13, 32 to 35, and Comparative Examples 1 and 5 do not contain coloring materials, a similar solid image was recorded on an OHP film (product name "KOKUYO OHP Film VF-1420N", manufactured by KOKUYO) so that the recorded image could be easily confirmed. The recorded image was observed, and the intermittent ejection stability was evaluated according to the following evaluation criteria. If the image does not have unevenness even if the rest time is long, it means that the intermittent ejection stability is excellent. A: No unevenness was observed in the image even with a 10 second rest period. B: Unevenness was observed in the image after a 10 second rest period, but no unevenness was observed in the image after a 5 second rest period. C: Unevenness was observed in the image after a rest period of 5 seconds.

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Claims

1. An inkjet recording method for recording an image on a recording medium by using an inkjet recording device including: an aqueous liquid composition; a storage unit for storing the liquid composition; a liquid ejection head for ejecting the liquid composition supplied from the storage unit through a supply system; and a detector for detecting a state of the liquid composition, the liquid composition contains (1) a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group, the material being selected from the group consisting of a coloring material, a resin, and a reactant, and (2) a nonionic surfactant; The electrical conductivity of the liquid composition is 10 μS / cm or more; the liquid ejection head comprises an ejection element substrate having an ejection port for ejecting the liquid composition and including a liquid chamber filled with the liquid composition, and a circulation flow path through which the liquid composition circulates from the container to the liquid ejection head via the liquid chamber, the detector detects the state of the liquid composition based on electrical conduction between a pair of electrodes disposed in the supply system; an inkjet recording method characterized in that the ejection element substrate comprises: a heater for liquid ejection arranged in a flow path through which the liquid composition flows, the heater communicating with the ejection port; a first protective layer arranged at a position in the flow path corresponding to the heater, blocking contact between the heater and the liquid composition in the flow path; a second protective layer made of a metal material arranged at a position corresponding to the heater in the flow path and in contact with the liquid composition; and a means for applying a voltage so that the second protective layer becomes an electrode charged with the same polarity as the material, and so that a portion that is conductive via the liquid composition becomes an electrode charged with a polarity opposite to that of the material.

2. 2. The inkjet recording method according to claim 1, wherein a voltage Ea (V) applied to the electrode when the detector detects the state of the liquid composition and a voltage Eb (V) applied to the second protective layer when the liquid ejection head ejects the liquid composition satisfy the relationship Eb<2.5≦Ea.

3. 2. The ink jet recording method according to claim 1, wherein the liquid composition has a conductivity of 100 [mu]S / cm or more.

4. 2. The ink jet recording method according to claim 1, wherein the metal material forming the second protective layer is at least one selected from the group consisting of iridium and ruthenium.

5. 2. The ink jet recording method according to claim 1, wherein the liquid composition flows through the circulation flow path at a circulation flow rate of 0.1 mm / s or more.

6. 6. The inkjet recording method according to claim 1, wherein the colorant is at least one selected from the group consisting of a self-dispersing pigment having an anionic group and a resin-dispersed pigment dispersed with a resin dispersant having an anionic group.

7. 6. The inkjet recording method according to claim 1, wherein the resin is at least one selected from the group consisting of resin particles formed of a resin having an anionic group and resin particles dispersed with a dispersant having an anionic group.

8. 6. The ink jet recording method according to claim 1, wherein the reactant is a polyvalent metal ion.

9. An inkjet recording apparatus comprising: an aqueous liquid composition; a container for containing the liquid composition; a liquid ejection head for ejecting the liquid composition supplied from the container through a supply system; and a detector for detecting a state of the liquid composition, the liquid composition contains (1) a material that can be dissolved or dispersed in the liquid composition by the action of an ionic group, the material being selected from the group consisting of a coloring material, a resin, and a reactant, and (2) a nonionic surfactant; The electrical conductivity of the liquid composition is 10 μS / cm or more; the liquid ejection head comprises an ejection element substrate having an ejection port for ejecting the liquid composition and including a liquid chamber filled with the liquid composition, and a circulation flow path through which the liquid composition circulates from the container to the liquid ejection head via the liquid chamber, the detector detects the state of the liquid composition based on electrical conduction between a pair of electrodes disposed in the supply system; an inkjet recording device characterized in that the ejection element substrate comprises: a heater for liquid ejection arranged in a flow path through which the liquid composition flows, the heater communicating with the ejection port; a first protective layer arranged at a position in the flow path corresponding to the heater, blocking contact between the heater and the liquid composition in the flow path; a second protective layer made of a metal material arranged at a position corresponding to the heater in the flow path and in contact with the liquid composition; and a means for applying a voltage so that the second protective layer becomes an electrode charged with the same polarity as the material, and so that a portion that is conductive via the liquid composition becomes an electrode charged with a polarity opposite to that of the material.

10. A liquid composition for use in an inkjet recording method for recording an image on a recording medium by using an inkjet recording apparatus comprising: an aqueous liquid composition; a storage unit for storing the liquid composition; a liquid ejection head for ejecting the liquid composition supplied from the storage unit via a supply system; and a detector for detecting a state of the liquid composition, (1) a material selected from the group consisting of a coloring material, a resin, and a reactant, which can be dissolved or dispersed in the liquid composition by the action of an ionic group, and (2) a nonionic surfactant; Its electrical conductivity is 10 μS / cm or more, the liquid ejection head comprises an ejection element substrate having an ejection port for ejecting the liquid composition and including a liquid chamber filled with the liquid composition, and a circulation flow path through which the liquid composition circulates from the container to the liquid ejection head via the liquid chamber, the detector detects the state of the liquid composition based on electrical conduction between a pair of electrodes disposed in the supply system; The liquid composition is characterized in that the ejection element substrate comprises: a heater for liquid ejection arranged in a flow path through which the liquid composition flows, the heater communicating with the ejection port; a first protective layer arranged at a position in the flow path corresponding to the heater, which blocks contact between the heater and the liquid composition in the flow path; a second protective layer made of a metallic material arranged at a position corresponding to the heater in the flow path and in contact with the liquid composition; and a means for applying a voltage so that the second protective layer becomes an electrode charged with the same polarity as the material, and so that a portion that is conductive via the liquid composition becomes an electrode charged with a polarity opposite to that of the material.

Images