Inkjet recording method, and inkjet recording device

Abstract

To provide an inkjet recording method that uses a miniaturized inkjet recording device mounted with a recording unit in a form in which a recording head is assembled in an ink storage part, and is excellent in sticking recoverability while maintaining strength of the recording unit, even in a case of using aqueous ink containing a pigment.SOLUTION: An inkjet recording method records an image using an inkjet recording device which includes aqueous ink, an ink storage part formed of a thermoplastic resin composition containing a filler material, and a recording head for discharging the aqueous ink supplied from the ink storage part. The ink storage part 37 has three or more storage parts which are each independently divided and are arrayed in a predetermined one direction, and specific gravity of the pigment in the aqueous ink stored in the storage part arranged inside is large compared to specific gravity of the pigment in the aqueous ink stored in the storage parts arranged on both ends.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] In recent years, the demand for home inkjet recording devices has increased due to an increase in remote work at home. In addition, there is a demand for inkjet recording devices to be further miniaturized for home use. In order to miniaturize inkjet recording devices, miniaturization of the recording head and ink storage unit is essential. For example, there is an inkjet recording device equipped with a miniaturized recording unit that integrates the ink storage unit and the recording head.

[0003] Some of these inkjet recording devices employ a recording head that ejects ink by the action of thermal energy, from the viewpoint of enabling a more compact design. Also, efforts have been made to miniaturize the recording head by providing ejection port rows that eject ink of multiple colors on the same recording element substrate. Still other inkjet recording devices have a recording unit that is miniaturized by bonding the recording head to the ink storage section without using any other members. The ink storage section is made of a thermoplastic resin to reduce the weight of the recording unit and to reduce the rigidity required for the carriage section, thereby miniaturizing the device.

[0004] However, ink storage parts made only of thermoplastic resins have the problem that they are easily deformed and easily cracked due to external pressure such as the impact of being dropped. To solve these problems, an ink storage container has been proposed that is made of a material in which a filler such as glass filler is added to a thermoplastic resin, thereby reducing the linear expansion coefficient (Patent Document 1).

[0005] In the case of inkjet recording devices that are also expected to output documents for business purposes such as remote work at home, a high level of robustness is required for color images, and therefore pigment inks using pigments as coloring materials are preferably used. From the viewpoint of image color development, phthalocyanine pigments are widely used as pigments for cyan inks, quinacridone pigments are widely used as pigments for magenta inks, and azo pigments are widely used as pigments for yellow inks. If ink containing pigments as coloring materials is left without being discharged for a long period of time, it may become stuck at the discharge port of the recording head, making it difficult to discharge. For this reason, inkjet recording devices equipped with a means for capping and sucking the discharge port to recover from the stuck state are widely used. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-142935 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have studied an ink storage section formed of a thermoplastic resin composition containing a filler material, as proposed in Patent Document 1. Specifically, a recording unit (hereinafter, also simply referred to as a "recording unit") formed by bonding a recording head to this ink storage section was prepared. Then, cyan, magenta, and yellow pigment inks were respectively stored in the divided storage sections of an ink storage container (ink storage section) having the structure disclosed in Patent Document 1, and left for three months in an environment at a temperature of 35°C and a relative humidity of 20%. Then, after leaving it, an image was recorded without performing a suction operation, and for each ink, the ink was fixed near the ejection port, causing non-ejection. When a suction operation was performed, it was found that the number of suction operations required to resolve the non-ejection differed for each color of ink, and it was necessary to improve the fixation recovery property.

[0008] Therefore, an object of the present invention is to solve the problems that arise when using a recording device equipped with a recording unit in which a recording head is incorporated in an ink reservoir formed of a thermoplastic resin composition containing a filler material, and using an aqueous ink containing a pigment. That is, an object of the present invention is to provide an inkjet recording method that is excellent in adhesion recovery of an aqueous ink containing a pigment while maintaining the strength of the recording unit even when using such a miniaturized recording device. Another object of the present invention is to provide an inkjet recording device used in this inkjet recording method. [Means for solving the problem]

[0009] That is, according to the present invention, there is provided an inkjet recording method comprising the steps of: using an inkjet recording device comprising: an aqueous ink containing a pigment; an ink storage section formed of a thermoplastic resin composition containing a filler material and containing the aqueous ink; and a recording head attached to the ink storage section and having an ejection port for ejecting the aqueous ink supplied from the ink storage section; and applying the aqueous ink ejected from the ejection port to a recording medium to record an image, wherein the ink storage section has three or more storage sections divided independently of one another, the storage sections are arranged in a predetermined direction, and the specific gravity of the pigment in the aqueous ink contained in the storage section located on the inside is greater than the specific gravity of the pigment in the aqueous ink contained in the storage sections located at both ends. Effect of the Invention

[0010] According to the present invention, it is possible to use a recording device equipped with a recording unit in which a recording head is incorporated in an ink reservoir formed of a thermoplastic resin composition containing a filler material, and to solve the problems that arise when using aqueous ink containing a pigment. That is, even when using such a miniaturized recording device, it is possible to provide an inkjet recording method that is excellent in adhesion recovery of aqueous ink containing a pigment while maintaining the strength of the recording unit. Furthermore, according to the present invention, it is possible to provide an inkjet recording device used in this inkjet recording method. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view illustrating an embodiment of an inkjet recording apparatus of the present invention. [Diagram 2] 1 is a perspective view showing a schematic internal structure of an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 3] 1A and 1B are diagrams illustrating an example of a recording unit, in which FIG. 1A is a perspective view and FIG. 1B is a perspective view in an exploded state. [Figure 4] 1A and 1B are diagrams showing an example of a recording unit, in which (a) is a diagram seen from above with a tank lid removed, and (b) is a diagram seen from below. [Diagram 5] 11A and 11B are diagrams showing another example of a recording unit, in which (a) is a diagram seen from above with a tank lid removed, and (b) is a diagram seen from below. [Figure 6] FIG. 2 is a schematic diagram showing an example of a suction unit. [Figure 7A] FIG. 4 is a schematic diagram showing an example of an arrangement mode of the storage parts. [Figure 7B] 13 is a schematic diagram showing another example of an arrangement mode of the storage parts. FIG. [Figure 7C] 13 is a schematic diagram showing another example of an arrangement mode of the storage parts. FIG. [Figure 7D] 13 is a schematic diagram showing another example of an arrangement mode of the storage parts. FIG. [Figure 7E] 13 is a schematic diagram showing another example of an arrangement mode of the storage parts. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in more detail below with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is present in the ink in the form of dissociation into ions, but for convenience, it is expressed as "containing a salt." In addition, water-based ink for inkjet printing may be simply referred to as "ink." Physical property values ​​are values ​​at room temperature (25°C) unless otherwise specified.

[0013] The present inventors have investigated the factors that cause the adhesion recovery to decrease when an inkjet recording device is used that is equipped with a recording unit in which a recording head is incorporated in an ink storage section formed of a thermoplastic resin composition containing a filler material. Specifically, the inventors have investigated the reasons why the adhesion recovery to decrease occurs due to differences in the number of suction operations required to resolve non-ejection for each color of ink.

[0014] A recording unit in which a recording head is incorporated in an ink reservoir formed of a thermoplastic resin composition containing a filler material is usually stored with the ink reservoir filled with ink, and is set in an inkjet recording device when the device is first used. As a result of the investigation, it was found that inorganic metals such as calcium (Ca), magnesium (Mg), iron (Fe), and aluminum (Al) are eluted from the filler material during storage and are easily dissolved in the ink. In addition, when a pigment ink containing a resin is used, the pH of the ink may be set high in order to suppress the precipitation of the resin. However, it was found that inorganic metals are more easily dissolved in ink with a high pH setting. It is considered that when inorganic metals are dissolved in the ink, the dispersion state of the pigment is easily destabilized, and the fixation recovery property is reduced.

[0015] In addition, the gas barrier properties of the ink storage portion formed of the thermoplastic resin composition containing the filler material are not necessarily high. For this reason, the liquid components such as water in the ink stored in the ink storage portion gradually evaporate, causing the pigment concentration in the ink to relatively increase, destabilizing the pigment dispersion state and promoting the sedimentation of the pigment, which are thought to be factors in the deterioration of the fixation recovery properties.

[0016] Furthermore, the inventors have produced an ink storage unit having three or more storage sections that are divided independently of each other and arranged in a predetermined direction. Then, cyan ink, magenta ink, and yellow ink are stored in the storage sections arranged in a row, respectively, and left for three months in an environment at a temperature of 35°C and a relative humidity of 20%, which are conditions under which the inks tend to evaporate. After that, a fixation recovery test was carried out to recover the fixation of the ink by performing a suction operation. As a result, it was found that the number of suction operations required to recover the fixation differed depending on the ink. Specifically, it was found that the number of suction operations required to recover the fixation of the cyan ink was greater than the specific gravity of the quinacridone pigment and azo pigment used as the pigments of the magenta ink, and the specific gravity of the azo pigment used as the pigment of the yellow ink. It is believed that the pigment, which has a relatively large specific gravity, is prone to settling, which makes the cyan ink more likely to adhere, resulting in a decrease in adhesion recovery.

[0017] Next, the inventors prepared an ink storage unit having three or more storage parts that are divided independently of each other and arranged in a predetermined direction. They found that the fixation recovery property can be improved by making the specific gravity of the pigment in the water-based ink stored in the storage part arranged on the inside larger than the specific gravity of the pigment in the water-based ink stored in the storage parts arranged on both ends, and arrived at the present invention. When three or more storage parts are arranged in one direction, water moves from the storage parts arranged on both sides to the storage part arranged on the inside, and the water content of the ink stored in the storage part arranged on the inside increases slightly (humidifies). Furthermore, since the storage part arranged on the inside has a relatively small contact area with the outside air, the water in the ink stored is less likely to evaporate compared to the storage parts arranged on both sides. Then, by storing an ink containing a pigment that has a relatively large specific gravity and is more likely to settle in the storage part arranged on the inside, it is possible to reduce the fixation of the cyan ink, which is more likely to fix due to settling. As a result, it is possible to reduce the difference in fixation recovery property between inks, and the number of suction operations required for fixation recovery can be reduced, and fixation recovery property can be improved.

[0018] <Inkjet recording method and inkjet recording apparatus> The inkjet recording method of the present invention is a recording method using an inkjet recording device including an ink containing a pigment, an ink storage section that stores the ink, and a recording head that is bonded to the ink storage section. The ink storage section is formed of a thermoplastic resin composition that contains a filler material. The recording head is formed with an ejection port that ejects the ink supplied from the ink storage section. The inkjet recording method of the present invention includes a step of applying the ink ejected from the ejection port to a recording medium to record an image. The ink storage section has three or more storage sections that are divided independently of each other, and these storage sections are arranged in a predetermined direction. The specific gravity of the pigment in the ink stored in the storage section located inside is greater than the specific gravity of the pigment in the ink stored in the storage sections located at both ends.

[0019] The inkjet recording device of the present invention is an inkjet recording device including an ink containing a pigment, an ink storage section that stores the ink, and a recording head that is bonded to the ink storage section. The ink storage section is formed of a thermoplastic resin composition that contains a filler material. The recording head is formed with an ejection port that ejects the ink supplied from the ink storage section. The ink storage section has three or more storage sections that are divided independently of each other, and these storage sections are arranged in a predetermined direction. The specific gravity of the pigment in the ink stored in the storage section located on the inside is greater than the specific gravity of the pigment in the ink stored in the storage sections located at both ends.

[0020] (Inkjet recording device) Fig. 1 is a perspective view showing a schematic diagram of an embodiment of an inkjet recording apparatus of the present invention. As shown in Fig. 1, an inkjet recording apparatus 70 of this embodiment has an exterior 71 and a cover member 72 provided on the upper surface of the exterior 71. The cover member 72 is a member that can be opened and closed in the vertical direction, and by opening it in the upward direction, the inside of the inkjet recording apparatus 70, which has a substantially rectangular parallelepiped shape, can be seen.

[0021] FIG. 2 is a perspective view showing a schematic internal structure of an embodiment of an inkjet recording device of the present invention. A recording unit 30 in which a recording head and an ink storage unit are integrally formed is configured to be mountable on a carriage (support member) 81, and is mounted on the carriage by connecting to a joint (not shown) provided on the upper part of the carriage 81. The recording unit 30 is connected to a tube 82 which is a flexible member, and the other end of the tube 82 is connected to a main tank (second ink storage unit) 73 which is a second ink storage unit. When the recording unit 30 is mounted on the carriage 81, the recording head 36 (FIG. 3) communicates with the main tank 73 via the joint and the tube 82. The inkjet recording device 70 of this embodiment is a serial scan type recording device, and the carriage 81 is guided by a guide shaft so as to be freely movable in the main scanning direction. The carriage 81 reciprocates in the main scanning direction by a driving force transmission mechanism such as a carriage motor and a belt which transmits the driving force of the carriage motor (both not shown).

[0022] The recording medium is transported in a sub-scanning direction perpendicular to the main scanning direction of the carriage 81 by the transport roller. The inkjet recording device 70 moves the recording head 36 (FIG. 3) in the main scanning direction while repeatedly performing a recording operation in which ink is ejected toward a recording area of ​​the recording medium on the platen, and a transport operation in which the recording medium is transported in the sub-scanning direction by a distance corresponding to the recording width. In this way, images are sequentially recorded on the recording medium.

[0023] FIG. 3 is a drawing showing an example of a recording unit, where (a) is a perspective view and (b) is a perspective view in an exploded state. The recording unit shown in FIG. 3 has an ink storage section 37, which is a housing formed of a thermoplastic resin composition containing a filler material, and a recording head 36. Examples of the thermoplastic resin composition include polyester, polycarbonate, polypropylene, polyethylene, polystyrene, polyphenylene ether, and mixtures or modified products thereof. Examples of the filler material include flake fillers such as mica and fibrous fillers such as glass fiber. Glass fiber is a material called E-glass (alkali-free glass), and is generally cut to a predetermined length (chopped strands). It is preferable that the recording head 36 is bonded to the ink storage section 37 without any other members. The ink storage section 37 is lightweight because it is a housing formed of a thermoplastic resin composition. By bonding the recording head 36 to the ink storage section 37 without any other members such as a heat sink, the entire recording unit is made smaller and lighter. By using such a recording unit, the inkjet recording device as a whole can be made smaller and lighter. The heat sink can be made of a material such as a metal oxide, such as alumina. In addition, the ink storage section 37 made of a thermoplastic resin composition containing a filler has a lower linear expansion coefficient than one made of a thermoplastic resin that does not contain a filler. This prevents the housing from being deformed and also prevents cracks caused by external pressure, such as when the housing is dropped.

[0024] The recording head 36 is provided with a plurality of ejection ports for ejecting ink, and an energy generating element for generating energy for ejecting ink. The energy generating element can be driven by, for example, power supplied through the electric wiring member 32. The energy generating element is an element that generates thermal energy or mechanical energy, and can eject ink from the ejection port by the action of the generated energy. An example of the element that generates thermal energy is an electrothermal converter. An example of the element that generates mechanical energy is a piezoelectric element. Among these, a recording head that ejects ink by the action of thermal energy is preferable because it can be designed to be compact.

[0025] The recording head 36 has an ejection port surface in which multiple ejection port arrays each consisting of multiple ejection ports are arranged on the same recording element substrate. By arranging multiple ejection port arrays on the same recording element substrate, it is possible to eject multiple inks with one recording unit, and the inkjet recording device can be made smaller. It is preferable that the multiple ejection port arrays are arranged in a direction (sub-scanning direction) perpendicular to the reciprocating movement direction (main scanning direction) of the recording unit in which the recording head is incorporated. In addition, by configuring the ejection port array with multiple ejection ports, the area that can be printed during the reciprocating movement of the recording head is widened, allowing for faster printing.

[0026] Sponge-like ink absorbers 34a to 34c are stored in the ink storage section 37. Filters 35a to 35c are disposed below the ink storage section 37 in the direction of gravity. By using the capillary force of the sponge-like ink absorbers 34a to 34c to generate negative pressure, it is possible to prevent ink from leaking from the ejection openings. Furthermore, by disposing the filters 35a to 35c, it is possible to prevent fine foreign matter such as dust from entering the ejection openings. Furthermore, by providing the tank lid 33 by thermocompression bonding above the ink storage section 37 in the direction of gravity, it is possible to prevent ink from leaking from the ink storage section 37.

[0027] The printhead preferably has a heating means for heating the ink in the printhead. The heating means may be any means capable of heating the ink in the printhead to a temperature higher than the printing environment temperature, such as room temperature (25° C.). Examples of such heating means include a heater for adjusting the ink temperature, which is disposed in contact with the printhead, and a heater for ink ejection. To heat the ink using a heater for ink ejection, for example, a current that is not strong enough to eject the ink may be repeatedly applied.

[0028] The inkjet recording device preferably further includes a second ink storage unit such as a main tank having a larger capacity than the ink storage unit (first ink storage unit) such as a sub-tank, and a tube through which ink flows between the second ink storage unit and the ink storage unit. Considering the usage mode in remote work at home, it is important to reduce the frequency of replacing the ink cartridge as well as to reduce the size of the device. For this reason, by further providing a second ink storage unit such as a main tank, it is possible to reduce the frequency of ink replacement while avoiding an increase in the size of the device body. Hereinafter, an inkjet recording device in which only a first ink storage unit such as a sub-tank bonded to the recording head is provided as an ink storage unit is also referred to as a "first device configuration". In the case of the first device configuration, when the ink stored inside the ink storage unit is consumed, it is replaced with another ink storage unit (ink storage unit filled with ink). Therefore, compared to the second device configuration, the main tank and tube can be omitted, and the weight of the inkjet recording device can be reduced. An inkjet recording device further provided with a second ink containing unit, such as a main tank having a larger capacity than the sub-tank, as an ink containing unit, is also referred to as a "second device configuration." In the case of the second device configuration, for example, by forming a connection part for connecting to a tube on the tank lid 33 shown in FIG. 3, the ink containing unit 37 and the second ink containing unit, such as the main tank, can be connected.

[0029] In the case of the second device configuration, the frequency of ink replacement is reduced compared to the first device configuration, so that the period during which the ink is held in a stationary state in the main tank is longer. In addition, in the case of pigment ink, the pigment is more likely to settle if the period during which the ink is held in a stationary state is longer. The decrease in ejection performance due to adhesion occurs due to the ink drying in the flow path and the pigment coagulating, so it becomes more noticeable when an ink with a high pigment content is used. Depending on the usage conditions, the adhesion recovery performance of the second device configuration is often inferior to that of the first device configuration. In particular, adhesion due to sedimentation is more likely to occur in ink with a high pigment specific gravity. In contrast, the inkjet recording method of the present invention can reduce adhesion of ink with a high pigment specific gravity, so that it is possible to achieve both a reduction in the frequency of ink replacement and an improvement in adhesion recovery performance.

[0030] FIG. 4 is a diagram showing an example of a recording unit, in which (a) is a view from above with the tank lid removed, and (b) is a view from below (the recording head side). As shown in FIG. 4, the ink storage section 37 has three or more storage sections 31a to 31c that are divided independently from each other. These storage sections 31a to 31c are divided by a partition section 50 made of the same material as the housing, for example, and can store multiple types of ink individually. In addition, the recording head 36 has an ejection port surface in which multiple ejection port arrays 38a to 38c consisting of multiple ejection ports are arranged on the same recording element substrate. These ejection port arrays 38a to 38c correspond to the multiple types of ink individually stored in the storage sections 31a to 31c, respectively, and are arranged in a predetermined direction. The specific gravity of the pigment in the ink stored in the storage section 31b arranged on the inside is greater than the specific gravity of the pigment in the ink stored in the storage sections 31a and 31c arranged at both ends. Since the surface area of ​​the ink in the ink storage portion 31b located on the inside is relatively small, water is less likely to evaporate from the ink stored therein than in the ink storage portions 31a and 31c located on both sides. Furthermore, water moves from the ink storage portions 31a and 31c located on both sides to the ink storage portion 31b located on the inside, causing the water content of the ink stored in the ink storage portion 31b to increase slightly (become humidified). This is believed to reduce adhesion of the ink stored in the ink storage portion 31b, which contains a pigment with a relatively large specific gravity, and improve adhesion recovery.

[0031] FIG. 5 is a drawing showing another example of the recording unit, where (a) is a view from above with the tank lid removed, and (b) is a view from below (the recording head side). The ink storage section 57 shown in FIG. 5 has three or more storage sections 51a to 51c that are divided independently of each other, and these storage sections 51a to 51c are arranged in a predetermined direction. The arrangement direction of the multiple storage sections may be in one predetermined direction. For example, they may be arranged in a direction perpendicular to the main scanning direction of the recording head 36 as shown in FIG. 4, or they may be arranged in a direction parallel to the main scanning direction of the recording head 36 as shown in FIG. From the viewpoint of the strength of the ink storage section, it is particularly preferable that the arrangement direction of the multiple storage sections is arranged in a direction perpendicular to the main scanning direction of the recording head 36.

[0032] The ratio (A / B) of the length A in the longitudinal direction (sub-scanning direction) of the ink storage section to the length B in the lateral direction (main scanning direction) is preferably 2.0 times or more and 4.0 times or less (FIG. 4(a)). By making the A / B ratio 2.0 times or more, the width of the device can be made compact. In order to record an image on the entire surface of a recording medium using a so-called serial type inkjet recording device that records an image while scanning the recording head back and forth in the main scanning direction perpendicular to the conveying direction of the recording medium, it is necessary to move the ejection port array from one end of the recording medium to the other end. If the width of the recording head is wide, the width of the inkjet recording device will inevitably be wide. In addition, if the A / B ratio of the ink storage section is too large, when an external force is applied to the housing, stress is concentrated in the longitudinal direction, and deformation due to insufficient strength of the housing may easily occur. For this reason, the A / B ratio is preferably 4.0 times or less.

[0033] FIG. 6 is a schematic diagram showing an example of a suction means. As shown in FIG. 6, the inkjet recording device includes a cap 61 that abuts against an area including the discharge port surface of the recording head 36 and covers a plurality of discharge port rows. A tube 63 that functions as an air communication part and a waste ink tube 66 that discharges waste ink that is accumulated in the cap 61 and is not used for recording are connected to the cap 61. An air communication valve 62 is provided in the middle of the tube 63. Waste ink discharged from the discharge ports of the recording head 36 is stored in a waste ink storage part 67. A suction valve 64 is provided in the middle of the waste ink tube 66, and a suction operation is performed to discharge unnecessary waste ink using a pump 65. In this example, the suction operation using a pump provided downstream of the recording head has been described as an example, but waste ink not used for recording may be discharged from the discharge ports by a pressurizing operation using a pump provided upstream of the recording head.

[0034] In cases where ink dries and solidifies in flow paths connected to the ejection ports, making normal ejection difficult, the state where normal ejection is difficult can be resolved by circulating new ink from the ink storage section 37 through a suction operation. Normally, when multiple ejection port arrays are arranged on the same recording element substrate, the suction operation is performed using the same cap. For example, when ejection port arrays that eject cyan ink, magenta ink, and yellow ink are arranged on the same recording element substrate, these inks are sucked together using the same cap. Generally, when inks that are easy to remove from the solidification and inks that are difficult to remove from the solidification are mixed, the suction operation of the inks that are difficult to remove from the solidification must be continued even though the solidification of the ejection ports that eject the inks that are easy to remove from the solidification has been removed, and the recovery from the solidification is reduced.

[0035] (Water-based ink) The inkjet recording method of the present invention includes a step of recording an image by using an ink containing a pigment and applying the ink ejected from an ejection port to a recording medium. The ink includes, for example, cyan ink, magenta ink, and yellow ink. The components constituting the ink are described below. When it is not necessary to distinguish between cyan ink, magenta ink, and yellow ink, each ink is collectively referred to as "ink". Within the range of the preferred embodiments shown below, the inks of each color may have the same composition or different compositions.

[0036] [Colorant] Pigments are used as the coloring material for the ink in order to improve image fastness, etc. The specific gravity of the pigment in the ink contained in the innermost storage section among the three or more storage sections arranged in a predetermined direction must be greater than the specific gravity of the pigment in the ink contained in the storage sections arranged at both ends.

[0037] From the viewpoint of color development, it is preferable to use a phthalocyanine pigment for cyan ink, a quinacridone pigment for magenta ink, and an azo pigment for yellow ink. The specific gravity of the pigment is preferably 1.0 or more and 2.0 or less, and more preferably 1.2 or more and 2.0 or less. The numbers in parentheses attached to the pigments shown below are the true specific gravity of the pigment. Examples of pigments used in cyan ink include CI Pigment Blue 15:3 (1.6) and CI Pigment Blue 15:4 (1.7). Examples of pigments used in magenta ink include quinacridone pigments such as CI Pigment Red 122 (1.4), CI Pigment Red 202 (1.5), and CI Pigment Violet 19 (1.5). In order to adjust the color tone, the magenta ink may contain a diketopyrrolopyrrole pigment such as CI Pigment Red 254 (1.6), an azo pigment such as CI Pigment Red 150 (1.5), a dioxazine pigment such as CI Pigment Violet 23 (1.5), or a perylene pigment such as CI Pigment Red 149 (1.4) in combination with a quinacridone pigment. Examples of pigments used in the yellow ink include CI Pigment Yellow 74 (1.4), CI Pigment Yellow 128 (1.5), and CI Pigment Yellow 155 (1.4).

[0038] The specific gravity of the pigment is a value (true specific gravity) measured in accordance with JIS Z8807:2012, "Method of measuring density and specific gravity of solids". The specific gravity may be measured for a pigment appropriately taken out of a pigment dispersion or ink, or may be measured using the pigment dispersion or ink. The specific gravity of the pigment particles in the ink can be measured using a density specific gravity meter (for example, a portable density specific gravity meter under the trade name "DA-130N" (manufactured by Kyoto Electronics Co., Ltd.)). When measuring the specific gravity of the pigment particles using a pigment dispersion or ink, it is preferable to use a measurement sample that has been concentrated or diluted with water to adjust the content (mass%) of the pigment particles in the liquid to be within a range of 1.0 mass% to 10.0 mass% based on the total mass of the liquid. In addition, values ​​described in the Organic Pigment Handbook (written by Isao Hashimoto, Color Office Co., Ltd., 2006) may be used.

[0039] The pigment content (mass %) in the ink is preferably from 0.50 to 10.00 mass %, and more preferably from 1.00 to 8.00 mass %, based on the total mass of the ink.

[0040] Of the three or more storage sections arranged in a predetermined direction, the content of the pigment in the ink stored in the storage section arranged on the inside is preferably less than the content of the pigment in the ink stored in the storage sections arranged at both ends. When a suction operation is performed to eliminate the adhesion of ink, ink with a lower viscosity is sucked more efficiently. In addition, in the suction operation, a plurality of ejection ports corresponding to each ink are usually sucked together. When an ink whose adhesion has been eliminated and an ink whose adhesion has not been eliminated coexist, the negative pressure applied to the ink whose adhesion has not been eliminated decreases relatively. As a result, the degree of reduction in adhesion of the ink whose adhesion has not been eliminated tends to decrease. Here, by relatively reducing the content of the pigment in the ink stored in the storage section arranged on the inside, which is prone to adhesion, it is possible to reduce the difference in adhesion recovery between the inks, and the adhesion recovery can be further improved.

[0041] Examples of pigment dispersion methods include resin-dispersed pigments that use a resin (resin dispersant) as a dispersant, and self-dispersed pigments in which hydrophilic groups are bonded to the pigment particle surface. In addition, resin-bonded pigments in which organic groups containing a resin are chemically bonded to the pigment particle surface, and microcapsule pigments in which the pigment particle surface is coated with a resin, etc. can be used. Among these, it is particularly preferable to use a resin-dispersed pigment in which a resin dispersant having a hydrophobic portion and a hydrophilic portion is used, the hydrophobic portion of the resin dispersant is adsorbed to the pigment particle surface, and the pigment is dispersed by the hydrophilic portion.

[0042] As the resin dispersant, it is preferable to use a resin that can disperse the pigment in an aqueous medium by the action of an anionic group. As the resin dispersant, a water-soluble resin described below can be used. When a resin-dispersed pigment is used, the content (mass%) of the pigment in the ink is preferably 0.3 to 10.0 times the content (mass%) of the resin dispersant in terms of mass ratio.

[0043] 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.

[0044] The average particle diameter D50 (nm) of the pigment in the ink is preferably 80 nm or more and 200 nm or less, and more preferably 100 nm or more and 150 nm or less. In this specification, "average particle diameter" means "cumulative 50% particle diameter (D50) based on volume." The cumulative 50% particle diameter (D50) based on volume of the pigment can be measured using a particle size distribution measuring device using a dynamic light scattering method (for example, product name "UPA-EX150", manufactured by Nikkiso). The measurement conditions can be, for example, SetZero: 30 seconds, number of measurements: 3 times, and measurement time: 180 seconds.

[0045] Of the three or more storage sections arranged in a given direction, it is preferable that the average particle diameter of the pigment in the ink stored in the storage section located on the inside is smaller than the average particle diameter of the pigment in the ink stored in the storage sections located at both ends. By making the average particle diameter of the pigment in the ink stored in the storage section located on the inside, which is prone to adhesion, relatively smaller, it is possible to reduce the difference in adhesion recovery properties between inks, and further improve adhesion recovery properties.

[0046] [resin] The ink may contain a resin such as a water-soluble resin. The content (mass%) of the resin in the ink is preferably 0.10% by mass or more and 20.00% by mass or less, and more preferably 0.50% by mass or more and 15.00% by mass or less, based on the total mass of the ink. The resin may be added to the ink (i) to stabilize the dispersion state of the pigment, that is, as a resin dispersant or its auxiliary. Also, the resin may be added to the ink (ii) to improve various properties of the recorded image. 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.

[0047] Examples of the resin include acrylic resin, urethane resin, and olefin resin. Among them, acrylic resin and urethane resin are preferred, and acrylic resin is more preferred. The acrylic resin is preferably one having a hydrophilic unit as a hydrophilic part and a hydrophobic unit as a hydrophobic part as a constituent unit. 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. 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; anionic monomers such as anhydrides and salts of these acidic monomers; and the like. Examples of the cations constituting the salts of the acidic monomers include ions such as lithium, sodium, potassium, ammonium, and organic ammonium. The hydrophobic unit is a unit that does not have a hydrophilic group such as an anionic group. The hydrophobic unit can be formed, for example, by polymerizing a hydrophobic monomer that does not have a hydrophilic group such as an anionic group. Examples of hydrophobic monomers 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.

[0048] Among them, acrylic resins having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one monomer selected from the group consisting of a monomer having an aromatic ring and a (meth)acrylic acid ester monomer are preferred. In particular, acrylic resins having a hydrophilic unit derived from (meth)acrylic acid and a hydrophobic unit derived from at least one monomer of styrene and α-methylstyrene are preferred. These acrylic resins are easily interacted with pigments, and therefore can be suitably used as resin dispersants for dispersing pigments.

[0049] The urethane resin can be obtained, for example, by reacting a 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.

[0050] In this specification, "a resin is water-soluble" means that when the resin is neutralized with an alkali equivalent to the acid value, it exists in an aqueous medium in a state in which it does not form particles whose particle size can be measured by dynamic light scattering. 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 dynamic light scattering, if particles having a particle size are not measured, the resin can be determined to be water-soluble. On the other hand, if particles having a particle size are measured, the resin can be determined to be "resin particles" (i.e., "water-dispersible resin"). The measurement conditions at this time can be, for example, as follows. [Measurement conditions] SetZero: 30 seconds Number of measurements: 3 Measurement time: 180 seconds

[0051] As the particle size distribution measuring device, a particle size analyzer using a dynamic light scattering method (for example, the product name "UPA-EX150" manufactured by Nikkiso Co., Ltd.) can be used. Of course, the particle size distribution measuring device and the measurement conditions to be used are not limited to those described above.

[0052] [Aqueous medium] The ink is an aqueous ink containing an aqueous medium that is water or a mixed solvent of water and a water-soluble organic solvent. As the water, deionized water (ion-exchanged water) is preferably used. The content (mass%) of water in the ink is preferably 50.00% by mass or more and 95.00% by mass or less based on the total mass of the ink.

[0053] As the water-soluble organic solvent, any of those usable for inkjet inks, such as alcohols, glycols, (poly)alkylene glycols, nitrogen-containing compounds, and sulfur-containing compounds, can be used. The content (mass%) of the water-soluble organic solvent in the ink is preferably 3.00 mass% or more and 50.00 mass% or less based on the total mass of the ink. Usually, a "water-soluble organic solvent" is liquid, but in the present invention, for the sake of convenience, those that are solid at 25°C (room temperature) are also included in the water-soluble organic solvent. Examples of water-soluble organic solvents that are generally used in aqueous inks and are solid at 25°C include 1,6-hexanediol, trimethylolpropane, ethylene urea, urea, polyethylene glycol with a number average molecular weight of 1,000, and sugars.

[0054] Of the three or more storage sections arranged in a predetermined direction, the content of the water-soluble organic solvent in the ink stored in the storage section arranged on the inside is preferably higher than the content of the water-soluble organic solvent in the ink stored in the storage sections arranged at both ends. When storage sections each storing two inks with different contents of water-soluble organic solvent are arranged adjacent to each other, water moves from the ink with the higher content of water-soluble organic solvent to the ink with the lower content of water-soluble organic solvent. By relatively increasing the content of water-soluble organic solvent in the ink stored in the storage section arranged on the inside, water moves from the storage sections arranged at both ends to the storage section arranged on the inside, thereby further improving adhesion recovery.

[0055] [Surfactants] The ink preferably further contains a surfactant. Examples of the surfactant include anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, and other surfactants. Of these, it is preferable to use a nonionic surfactant.

[0056] Examples of anionic surfactants include polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkyl ether sulfonates, polyoxyethylene alkyl phenyl ether sulfate salts, polyoxyethylene alkyl phenyl ether sulfonates, alpha sulfo fatty acid ester salts, alkyl benzene sulfonates, alkyl phenol sulfonates, alkyl naphthalene sulfonates, alkyl tetralin sulfonates, and dialkyl sulfosuccinates. Examples of cationic surfactants include alkyl trimethyl ammonium salts and dialkyl dimethyl ammonium chlorides.

[0057] Examples of nonionic surfactants include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene alkyl phenyl ethers, fatty acid diethanolamides, and polyoxyethylene-polyoxypropylene block copolymers. Examples of amphoteric surfactants include alkyl carboxybetaines. Other examples of surfactants include fluorine-based surfactants, silicon-based surfactants, and the like.

[0058] The content (mass %) of the surfactant in the ink is preferably from 0.10 to 5.00% by mass, and more preferably from 0.10 to 2.00% by mass, based on the total mass of the ink.

[0059] [Other ingredients] In addition to the above components, the ink may contain various additives, such as antifoaming agents, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and reduction inhibitors, as necessary.

[0060] [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 static surface tension of the ink at 25°C is preferably 28 mN / m or more and 45 mN / m or less. Furthermore, the viscosity of the ink at 25°C is preferably 1.0 mPa·s or more and 5.0 mPa·s or less, and more preferably 1.0 mPa·s or more and 3.0 mPa·s or less. The pH of the ink at 25°C is preferably 5.0 or more and 9.5 or less.

[0061] Of the three or more storage sections arranged in a predetermined direction, the viscosity of the ink stored in the storage section arranged on the inside is preferably lower than the viscosity of the ink stored in the storage sections arranged at both ends. When a suction operation is performed to eliminate the adhesion of ink, ink with a lower viscosity is sucked more efficiently. In addition, in the suction operation, a plurality of ejection ports corresponding to each ink are usually sucked together. When ink whose adhesion has been eliminated and ink whose adhesion has not been eliminated coexist, the negative pressure applied to the ink whose adhesion has not been eliminated decreases relatively. As a result, there are cases where it is difficult to reduce the adhesion of the ink whose adhesion has not been eliminated. Here, by relatively lowering the viscosity of the ink stored in the storage section arranged on the inside, which is prone to adhesion, it is possible to reduce the difference in adhesion recovery between the inks, and the adhesion recovery can be further improved. The viscosity of the ink can be measured by a rotational viscometer. EXAMPLES

[0062] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples without departing from the gist of the invention. "Parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified.

[0063] <Preparation of pigment dispersion> Hereinafter, the average particle size of the pigment (cumulative 50% particle size on a volume basis, D50) was measured using a particle size analyzer using the dynamic light scattering method (product name "UPA-EX150", manufactured by Nikkiso) under the following conditions: SetZero: 30 seconds, number of measurements: 3, measurement time: 180 seconds.

[0064] (Pigment dispersion 1) The water-soluble resin was neutralized with potassium hydroxide in an amount equimolar to the acid value and dissolved in ion-exchanged water to prepare an aqueous solution of the resin dispersant with a resin (solid content) content of 20.00%. As the water-soluble resin, a styrene / acrylic acid copolymer (composition (molar) ratio = 33:67, weight average molecular weight 10,000, acid value 200 mg KOH / g) was used. A mixture of 15.0 parts of CI Pigment Blue 15:3, 22.5 parts of the aqueous solution of the resin dispersant, and 62.5 parts of water was placed in a sand grinder and dispersed for 1 hour, followed by centrifugation to remove coarse particles. The specific gravity of CI Pigment Blue 15:3 is 1.6 g / cm 3 After pressure filtration using a microfilter (manufactured by Fujifilm) with a pore size of 3.0 μm, an appropriate amount of ion-exchanged water was added to obtain pigment dispersion 1. The pigment content in pigment dispersion 1 was 10.00%, the resin dispersant content was 3.00%, and the average pigment particle diameter D50 was 120 nm.

[0065] (Pigment dispersion 2) Except for changing the dispersion treatment time from 1 hour to 45 minutes, Pigment Dispersion 2 was obtained in the same manner as Pigment Dispersion 1. The pigment content in Pigment Dispersion 2 was 10.00%, the resin dispersant content was 3.00%, and the average pigment particle diameter D50 was 129 nm.

[0066] (Pigment dispersion 3) Except for changing the dispersion treatment time from 1 hour to 30 minutes, Pigment Dispersion 3 was obtained in the same manner as Pigment Dispersion 1. The pigment content in Pigment Dispersion 3 was 10.00%, the resin dispersant content was 3.00%, and the average pigment particle diameter D50 was 135 nm.

[0067] (Pigment Dispersion 4) Pigment Dispersion Liquid 4 was obtained in the same manner as in Pigment Dispersion Liquid 1, except that CI Pigment Violet 19 was used instead of CI Pigment Blue 15:3. The specific gravity of CI Pigment Violet 19 was 1.5 g / cm 3 The pigment content in Pigment Dispersion Liquid 4 was 10.00%, the resin dispersant content was 3.00%, and the average pigment particle diameter D50 was 130 nm.

[0068] (Pigment Dispersion 5) Pigment Dispersion Liquid 5 was obtained in the same manner as in Pigment Dispersion Liquid 1, except that CI Pigment Red 150 was used instead of CI Pigment Blue 15:3. The specific gravity of CI Pigment Red 150 was 1.5 g / cm 3 The pigment content in Pigment Dispersion Liquid 5 was 10.00%, the resin dispersant content was 3.00%, and the average pigment particle diameter D50 was 130 nm.

[0069] (Pigment Dispersion 6) Pigment Dispersion Liquid 6 was obtained in the same manner as in Pigment Dispersion Liquid 1, except that CI Pigment Red 122 was used instead of CI Pigment Blue 15:3. The specific gravity of CI Pigment Red 122 was 1.4 g / cm 3 The pigment content in Pigment Dispersion Liquid 6 was 10.00%, the resin dispersant content was 3.00%, and the average particle diameter D50 of the pigment was 130 nm.

[0070] (Pigment Dispersion 7) Pigment Dispersion 7 was obtained in the same manner as in Pigment Dispersion 1, except that CI Pigment Yellow 74 was used instead of CI Pigment Blue 15:3. The specific gravity of CI Pigment Yellow 74 was 1.4 g / cm 3 The pigment content in Pigment Dispersion Liquid 7 was 10.00%, the resin dispersant content was 3.00%, and the average pigment particle diameter D50 was 130 nm.

[0071] (Pigment Dispersion 8) Pigment Dispersion Liquid 8 was obtained in the same manner as in Pigment Dispersion Liquid 1, except that CI Pigment Yellow 155 was used instead of CI Pigment Blue 15:3. The specific gravity of CI Pigment Yellow 155 was 1.5 g / cm 3 The pigment content in the pigment dispersion 8 was 10.00%, the resin dispersant content was 3.00%, and the average particle diameter D50 of the pigment was 130 nm.

[0072] <Preparation of dye-containing liquid> Dyes 1 to 3 shown below were each dissolved in ion-exchanged water to obtain liquids containing dyes 1 to 3, respectively (dye content: 10.00%). Dye 1: CI Direct Blue 199 Dye 2: CI Acid Red 289 Dye 3: CI Direct Yellow 132

[0073] <Ink Preparation> Each component (unit: %) shown in the upper part of Tables 1-1 and 1-2 was mixed, thoroughly stirred, and then pressure filtered through a polypropylene filter (manufactured by Pall) with a pore size of 2.5 μm to prepare each ink. In Tables 1-1 and 1-2, the numerical value attached to polyethylene glycol is the number average molecular weight. Also, "Acetylenol E100" is the trade name of an acetylene glycol-based nonionic surfactant (manufactured by Kawaken Fine Chemicals). The physical properties of the prepared inks are shown in the lower part of Tables 1-1 and 1-2. The viscosity of the ink was measured using a rotational viscometer (trade name "RE80 type viscometer", manufactured by Toki Sangyo) at a temperature condition of 25°C. The average particle size of the pigment in each ink was equivalent to the value measured for the pigment in the pigment dispersion.

[0074] TIFF2025024684000002.tif145170

[0075] TIFF2025024684000003.tif165170

[0076] <Recording unit configuration> A recording head was prepared that ejects ink by applying thermal energy. A recording element substrate constituting the recording head has an ejection port array in which 384 ejection ports are arranged at an array density of 600 dpi. The mass of an ink droplet ejected from one ejection port is 5.5 ng. A thermoplastic resin composition was molded to obtain recording units 1 to 9 having storage portions arranged in the manner shown in Figures 7A to 7E. The thermoplastic resin composition used was a mixture of 100 parts of a thermoplastic resin, which is a mixture of a styrene-based resin and polyphenylene ether, to which 25 parts of chopped strands of E glass having a length of 5 mm were added as a filler material. The characteristics of the obtained recording unit are shown in Table 2.

[0077] In the ink storage section 37 shown in FIG. 7A, three storage parts a to c are arranged in a direction perpendicular to the scanning direction of the recording head. In the ink storage section 77 shown in FIG. 7B, three storage parts a to c are arranged in a direction perpendicular to the scanning direction of the recording head. In the ink storage section 87 shown in FIG. 7C, three storage parts a to c are arranged in a direction parallel to the scanning direction of the recording head. In the ink storage section 107 shown in FIG. 7D, three storage parts a to c are arranged in a direction parallel to the scanning direction of the recording head. In the ink storage section 117 shown in FIG. 7E, three storage parts a to c are arranged in a T-shape, not in one direction. The ink storage sections of the recording units 7 and 8 shown in Table 2 were obtained by molding a thermoplastic resin that is a mixture of a styrene resin and polyphenylene ether, that is, a thermoplastic resin to which no filler material is added. Then, a recording head was attached to the obtained ink storage section without interposing any other member, to manufacture a recording unit.

[0078] TIFF2025024684000004.tif75170

[0079] <Evaluation> (Inkjet recording device) As the device 1, a product name "PIXUS TS5130S" (manufactured by Canon) was prepared as an inkjet recording device of the type in which the ink contained in the ink container (ink cartridge) is replaced with a new ink container filled with ink when the ink is consumed. As the device 2, a product name "G3370" (manufactured by Canon) was prepared as an inkjet recording device of the type in which the ink container (sub tank) on the carriage and the ink container (main tank) placed inside the device are connected by a tube through which the ink flows. These devices were modified so that the recording unit prepared above could be mounted. In this embodiment, the recording duty of a solid image recorded under the condition that two ink droplets with a mass of 5.5 ng per droplet are applied to a unit area of ​​1 / 600 inch x 1 / 600 inch is defined as 100%. In the present invention, in the evaluation criteria for each item shown below, "A" and "B" were considered to be acceptable levels, and "C" was considered to be an unacceptable level. The evaluation results are shown in Table 3. In Table 3, the symbols (a to c) indicating the positions of each color ink correspond to the symbols (a to c) in FIGS. 7A to 7E.

[0080] (Strength of ink storage section) To promote thermal deformation of the ink storage part (housing), the recording unit was stored in an environment at a temperature of 60°C for one month. With the top surface of the ink storage part facing downward in the direction of gravity and the ejection port surface of the recording head facing upward, the recording unit was dropped twice onto lauan wood from a height of 80 cm. After the drop, the ink storage part of the recording unit was visually observed and the strength of the ink storage part was evaluated according to the evaluation criteria shown below. A: No cracks or chips occurred in the ink storage area. B: Cracks or chips were found in the ink storage area, but no ink leakage was observed. C: Cracks or chips were found in the ink storage area, and ink leakage was confirmed.

[0081] (Adhesion recovery) The ink container was filled with the type of ink shown in Table 3, and the ink was attached to an inkjet recording device. A pump was used to supply ink to the recording head, and a nozzle check pattern for device 1 or 2 was recorded. After confirming that the ink was discharged from all of the nozzles, the device was left for three months in an environment with a temperature of 35°C and a relative humidity of 20%. After leaving the device, the number of times that suction was performed until the ink adhesion was restored was counted, and the adhesion recovery property was evaluated according to the evaluation criteria shown below. A: The number of suction operations required until ink was ejected from all of the ejection ports was two or less. B: The number of suction operations required until ink was ejected from all of the ejection ports was three. C: The number of suction operations required until ink was ejected from all of the ejection ports was four or more.

[0082] (Device size) Device 1 or 2 was modified so that a recording unit could be installed. The size of the device before and after the modification was compared, and the device size was evaluated according to the evaluation criteria shown below. A: We were able to modify it and make it smaller. B: It has been modified to the same size. C: It was modified and enlarged.

[0083] TIFF2025024684000005.tif255166

Claims

1. an inkjet recording device is used, the inkjet recording device comprising: an aqueous ink containing a pigment; an ink storage section for storing the aqueous ink and formed of a thermoplastic resin composition containing a filler material; and a recording head attached to the ink storage section and having an ejection port for ejecting the aqueous ink supplied from the ink storage section; An inkjet recording method comprising a step of applying the water-based ink ejected from the ejection orifice to a recording medium to record an image, the ink storage section has three or more storage sections that are divided independently from one another, and the storage sections are arranged in one predetermined direction; an ink jet recording method, characterized in that the specific gravity of the pigment in the aqueous ink contained in the storage portion located on the inside is greater than the specific gravity of the pigment in the aqueous ink contained in the storage portions located at both ends.

2. the water-based ink further contains a water-soluble organic solvent, 2. The inkjet recording method according to claim 1, wherein the content of the water-soluble organic solvent in the aqueous ink contained in the storage portion located on the inside is greater than the content of the water-soluble organic solvent in the aqueous ink contained in the storage portions located at both ends.

3. 2. The inkjet recording method according to claim 1, wherein the content of the pigment in the aqueous ink contained in the storage portion arranged on the inside is smaller than the content of the pigment in the aqueous ink contained in the storage portions arranged at both ends.

4. 2. The inkjet recording method according to claim 1, wherein an average particle diameter of the pigment in the aqueous ink contained in the storage portion arranged on the inside is smaller than an average particle diameter of the pigment in the aqueous ink contained in the storage portions arranged at both ends.

5. 2. The inkjet recording method according to claim 1, wherein the viscosity of the water-based ink contained in the containing portion disposed on the inner side is lower than the viscosity of the water-based ink contained in the containing portions disposed on both ends.

6. a nozzle row is formed in the recording head, the nozzle row being arranged in parallel with a longitudinal direction of the ink storage section; 6. The ink jet recording method according to claim 1, wherein a ratio (A / B) of a length A in a longitudinal direction of the ink storage section to a length B in a lateral direction perpendicular to the longitudinal direction is 2.0 times or more and 4.0 times or less.

7. 6. The ink jet recording method according to claim 1, wherein the ink containing unit is replaced with another ink containing unit after the water-based ink contained therein is consumed.

8. 6. The inkjet recording method according to claim 1, further comprising: a second ink containing section having a larger capacity than the ink containing section; and a tube through which the water-based ink circulates between the second ink containing section and the ink containing section.

9. An inkjet recording device comprising: an aqueous ink containing a pigment; an ink storage section for storing the aqueous ink and formed of a thermoplastic resin composition containing a filler material; and a recording head bonded to the ink storage section and having an ejection port for ejecting the aqueous ink supplied from the ink storage section, the ink storage section has three or more storage sections that are divided independently from one another, and the storage sections are arranged in one predetermined direction; An inkjet recording device, characterized in that the specific gravity of the pigment in the water-based ink contained in the storage portion located on the inside is greater than the specific gravity of the pigment in the water-based ink contained in the storage portions located at both ends.

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