Inkjet recording method, and inkjet recording device

Abstract

To provide an inkjet recording method that uses an inkjet recording device mounted with a recording unit in a form in which a recording head is assembled in an ink storage part, and enables recording an image that is reduced in bleeding and has high quality, while maintaining strength of the recording unit, in a case of using aqueous ink containing a dye.SOLUTION: An inkjet recording method records an image using an inkjet recording device which includes aqueous ink containing a dye, an ink storage part formed a thermoplastic resin composition containing a filler material, and a recording head. The ink storage part has three or more storage parts which are each independently divided by a partition part arranged perpendicularly to its longitudinal direction, the storage parts are arrayed in a predetermined one direction, the aqueous ink contains cyan ink, magenta ink, and yellow ink, and dynamic surface tension γ10 at a life of 10 milliseconds of the ink corresponding to a discharge port array arranged at a center is smallest.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, an ink storage section made only of thermoplastic resin has problems in that it is easily deformed and easily cracked due to external pressure such as impact caused by dropping. To solve these problems, ink storage containers have been proposed that are made of a material in which a filler such as a glass filler is added to a thermoplastic resin, thereby reducing the linear expansion coefficient and increasing the geometric rigidity (Patent Documents 1 and 2). In particular, in recent years, there has been an increase in the number of occasions in which ink cartridges incorporating a recording head are mailed, raising concerns about increased external pressure, and there is a demand for preventing cracking and chipping of the ink storage section even in such a usage environment.

[0005] By the way, a photographic image may be recorded on the entire surface of a recording medium by applying ink to an area slightly larger than the recording medium. In order to accommodate the miniaturization of the device, a so-called serial type recording head is adopted for a home inkjet recording device, which records an image while scanning the recording head back and forth in a main scanning direction perpendicular to the conveying direction (sub-scanning direction) of the recording medium. In the case of such a serial type recording head, it is necessary to scan in the main scanning direction until the ejection port array moves outside the width of the recording medium. For this reason, in addition to the width of the recording medium, it is necessary to provide a space in the recording device that is the width of the recording head for scanning the recording head. Therefore, in order to further miniaturize the recording device, it is necessary to reduce such space, and it is considered effective to reduce the width of the recording head in the main scanning direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-142935 A [Patent Document 2] JP 2007-038673 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors formed an ink storage section with a reduced width in the main scanning direction using a thermoplastic resin composition containing a filler material. Then, a recording head was attached to the formed ink storage section to prepare a recording unit (hereinafter, also simply referred to as a "recording unit"), and a water-based ink containing a dye was stored in the ink storage section. As a result, it was found that the ink storage section was prone to cracking due to external pressure such as an impact caused by dropping. In addition, when a color image was recorded with each of the cyan, yellow, and magenta inks stored in the ink storage section formed from the thermoplastic resin composition containing a filler material, bleeding sometimes occurred at the boundary between the colors.

[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 dye. That is, an object of the present invention is to provide an inkjet recording method that can record high-quality images with reduced bleeding while maintaining the strength of the recording head 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 using an inkjet recording apparatus including an aqueous ink containing a dye, an ink storage section formed of a thermoplastic resin composition containing a filler material and storing the aqueous ink, and a recording head attached to the ink storage section and having an ejection port array formed therein for ejecting the aqueous ink supplied from the ink storage section, the method comprising the steps of: applying the aqueous ink ejected from the ejection port array to a recording medium to record an image, the ink storage section having three or more storage sections independently divided from one another by partition sections arranged perpendicular to the longitudinal direction of the ink storage section, The inkjet recording method is characterized in that the aqueous inks are arranged in a predetermined direction, the aqueous inks include cyan ink, magenta ink, and yellow ink, three rows of the ejection openings corresponding to the cyan ink, the magenta ink, and the yellow ink, respectively, are formed in the recording head along the longitudinal direction of the ink storage section, and among the dynamic surface tensions γ10 of the cyan ink, the magenta ink, and the yellow ink over a lifetime of 10 milliseconds, the dynamic surface tension γ10 of the ink corresponding to the ejection opening row located in the center of the three rows of the ejection openings over a lifetime of 10 milliseconds is the smallest. 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 storage section formed of a thermoplastic resin composition containing a filler material, and to solve the problems that arise when using an aqueous ink containing a dye. That is, it is possible to provide an inkjet recording method that can record high-quality images with reduced bleeding while maintaining the strength of the recording unit even when using such a miniaturized recording device. 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 produced an ink containing section with a reduced width in the main scanning direction by using a thermoplastic resin composition containing a filler material, and prepared a recording unit formed by bonding a recording head to the ink containing section, and investigated the cause of cracks occurring in the ink containing section due to external pressure such as an impact caused by dropping the ink containing section.

[0014] The ink storage section usually contains a sponge-like ink absorber and a filter is placed below in the direction of gravity, and the ink that permeates the filter flows out of an ink supply port provided at the bottom of the ink storage section and flows to the ejection port of the recording head. The ink storage section is also divided by partitions independently for each type of ink to be mounted. As shown in FIG. 7E, some conventional ink storage sections are divided by partitions arranged in a T-shape so that the distance from the ink storage section to the ejection port of the recording head (the length of the ink flow path) does not vary significantly depending on the type of ink. However, when the width of the ink storage section is reduced in the main scanning direction, there is only one contact point between the partition arranged parallel to the longitudinal direction (sub-scanning direction) of the ink storage section and the outer peripheral wall of the ink storage section, and it is considered that cracks are more likely to occur due to external pressure.

[0015] As a result of the investigation, the inventors produced an ink storage section having three or more storage sections that are mutually independent and divided by partitions arranged perpendicular to the longitudinal direction, and that are arranged in a predetermined direction. Inks including cyan ink, magenta ink, and yellow ink are stored in each of the three or more storage sections. By configuring the ink storage section in this way, each partition comes into contact with the outer peripheral wall of the ink storage section at two points, which is thought to improve the strength and make the ink storage section less likely to crack even when subjected to external pressure.

[0016] As described above, when an image is recorded with each of the cyan, yellow, and magenta inks contained in the ink storage portion formed of the thermoplastic resin composition containing the filler material, bleeding may occur at the boundary between the colors. The gas barrier property of the ink storage portion formed of the thermoplastic resin composition containing the filler material is not necessarily high. For this reason, liquid components such as water of the ink stored in the ink storage portion tend to gradually evaporate. In particular, when three or more storage portions are arranged in one direction, it is difficult to reduce the variation in the amount of evaporation of the liquid components from each storage portion compared to the above-mentioned T-shaped arrangement. When the amount of evaporation of water, which is the most likely to evaporate among the liquid components, differs, the ink with a small amount of water evaporation tends to maintain its surface tension compared to before evaporation, while the ink with a large amount of water evaporation tends to have a lower surface tension compared to before evaporation. As a result, it is considered that the fluctuation range from the surface tension set by the ink composition is likely to differ between the inks, and bleeding occurs at the boundary between the colors.

[0017] As a result of the inventors' investigation into such a problem, they found that it is possible to record an image with reduced bleeding by adopting the following configuration. That is, a plurality of ejection port arrays are arranged parallel to the longitudinal direction of the ink storage section, and three ejection port arrays corresponding to cyan ink, magenta ink, and yellow ink are formed in the recording head. Among the dynamic surface tensions γ10 of the cyan ink, magenta ink, and yellow ink at a life time of 10 milliseconds, the dynamic surface tension γ10 of the ink corresponding to the ejection port array arranged at the center of the three ejection port arrays at a life time of 10 milliseconds is the smallest. Ink with a small value of dynamic surface tension at a life time of 10 milliseconds tends to permeate quickly when applied to a recording medium. When the dynamic surface tension value of the ink corresponding to the ejection port array arranged at the center of the three ejection port arrays is minimized, the ink permeates quickly into the recording medium even if it mixes with the ink ejected from the ejection ports of the ejection port arrays arranged on both sides. Therefore, bleeding at the boundary can be further suppressed.

[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 dye, 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 array 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 mutually independent and divided by partitions that are arranged perpendicular to the longitudinal direction of the ink storage section, and these storage sections are arranged in a predetermined direction. The ink includes cyan ink, magenta ink, and yellow ink. Three rows of ejection ports corresponding to the cyan ink, magenta ink, and yellow ink, respectively, are formed in the recording head along the longitudinal direction of the ink storage section. Of the dynamic surface tensions γ10 of cyan ink, magenta ink, and yellow ink over a lifespan of 10 milliseconds, the dynamic surface tension γ10 of the ink corresponding to the ejection port array located in the center of the three ejection port arrays over a lifespan of 10 milliseconds is the smallest.

[0019] The inkjet recording device of the present invention is an inkjet recording device including an ink containing a dye, 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 mutually independent and divided by partitions that are arranged perpendicular to the longitudinal direction of the ink storage section, and these storage sections are arranged in a predetermined direction. The ink includes cyan ink, magenta ink, and yellow ink. Three ejection port rows corresponding to the cyan ink, magenta ink, and yellow ink, respectively, are formed in the recording head along the longitudinal direction of the ink storage section. Of the dynamic surface tensions γ10 at a life time of 10 milliseconds of the cyan ink, magenta ink, and yellow ink, the dynamic surface tension γ10 at a life time of 10 milliseconds of the ink corresponding to the ejection port row arranged in the center of the three ejection port rows is the smallest.

[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 ink is held stationary in the main tank is longer. Depending on the usage conditions, the degree of deterioration in ejection performance due to adhesion in the second device configuration is likely to be greater than the degree of deterioration in ejection performance due to adhesion in the first device configuration. Furthermore, if there is a difference in the degree of deterioration in ejection performance due to adhesion for each ink, the difference becomes greater. For this reason, generally, the second device configuration is likely to cause a problem that the amount of waste ink is even greater than that of the first device configuration. In contrast, in the inkjet recording method of the present invention, even when the second device configuration is used, it is possible to reduce the amount of waste ink, and it is possible to achieve both a reduction in the frequency of ink replacement and a reduction in the amount of waste ink.

[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 of each other. These storage sections 31a to 31c are divided by a partition section 50 arranged perpendicular to the longitudinal direction (sub-scanning direction) of the ink storage section 37, and can store multiple types of ink including cyan ink, magenta ink, and yellow ink individually. The partition section 50 is formed of, for example, the same material as the housing. In addition, the recording head 36 has an ejection port surface in which multiple ejection port rows 38a to 38c, each of which is composed of multiple ejection ports, are arranged on the same recording element substrate. These ejection port rows 38a to 38c correspond to the multiple types of inks individually stored in the storage sections 31a to 31c, respectively, and the storage sections 31a to 31c are arranged in a predetermined direction. Among the cyan, magenta, and yellow inks, it is preferable to store the ink with the highest dye content in the storage portion 31b located on the inside. The storage portion 31b located on the inside has a relatively small contact area with the outside air, so water is less likely to evaporate from the stored ink compared to the storage portions 31a and 31c located on both sides. Furthermore, water moves from the storage portions 31a and 31c located on both sides to the storage portion 31b located on the inside, and the water content of the ink stored in the storage portion 31b increases slightly (humidifies). This is thought to further suppress the occurrence of color unevenness and allow for more uniform and high-quality images to be recorded.

[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 4.4 times or less, and more 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 4.4 times or less, and more 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 rows are arranged on the same recording element substrate, the suction operation is performed using the same cap. For example, when ejection port rows for ejecting 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 for the inks that are difficult to remove from the solidification must be continued even though the solidification of the ejection ports ejecting the inks that are easy to remove from the solidification has been removed, and the amount of waste ink increases.

[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 dye and applying the ink ejected from an ejection port to a recording medium. The ink includes cyan ink, magenta ink, and yellow ink from the viewpoints of color development and color gamut. 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 scope of the preferred embodiments shown below, the inks of each color may have the same composition or different compositions.

[0036] [Colorant] A dye is used as the coloring material of the ink. Compared to a pigment contained in a dispersed state in an aqueous medium, when a dye that dissolves in an aqueous medium at a molecular level is used as the coloring material, an image with excellent gloss can be recorded on special inkjet paper such as glossy paper. Therefore, by using an ink containing a dye, an image of higher quality can be recorded. It is preferable that the ink does not contain a pigment as a coloring material.

[0037] Examples of dyes include direct dyes, acid dyes, basic dyes, disperse dyes, and food dyes. Among them, it is preferable to use dyes having an anionic group. Specific examples of dye skeletons include azo, triphenylmethane, phthalocyanine, azaphthalocyanine, xanthene, and anthrapyridone. It is also preferable to use dyes with CI numbers. For example, CI Food Black 2; CI Direct Black 195; CI Direct Yellow: 86, 132, 173; CI Acid Yellow: 17, 23; CI Acid Red: 52, 249, 289; CI Acid Blue 9; CI Direct Blue: 86, 199, and the like.

[0038] The content (mass %) of the dye in the ink is preferably from 0.10% to 15.00% by mass, and more preferably from 0.50% to 10.00% by mass, based on the total mass of the ink.

[0039] [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.

[0040] The water-soluble organic solvent may be any of those usable in inkjet inks, such as alcohols, glycols, (poly)alkylene glycols, nitrogen-containing compounds, and sulfur-containing compounds. The content (mass %) of the water-soluble organic solvent in the ink is preferably 3.00% by mass or more and 50.00% by mass or less, based on the total mass of the ink.

[0041] [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.

[0042] 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.

[0043] 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.

[0044] The ink preferably contains an acetylene glycol surfactant. The acetylene glycol surfactant has a good balance between the amount added to the ink and the ability to reduce surface tension. For this reason, by using an ink containing an acetylene glycol surfactant, it is possible to record images of higher quality.

[0045] 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.

[0046] [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.

[0047] [Ink properties] 〔viscosity〕 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. In addition, among the viscosities of the cyan ink, magenta ink, and yellow ink, the difference (η1-η2) between the maximum viscosity η1 (mPa·s) and the minimum viscosity η2 (mPa·s) is preferably 0.2 mPa·s or less. When "η1-η2" is 0.2 mPa·s or less, the three color inks are ejected uniformly, and the uniformity of the image can be further improved. The viscosity of the ink can be appropriately adjusted, for example, by setting the type and amount of the water-soluble organic solvent and surfactant.

[0048] [Static surface tension] The static surface tension of the ink at 25°C is preferably 28.0 mN / m or more and 45.0 mN / m or less. In addition, it is preferable that the length of the horizontal portion of the ink flow path through which the ink flows between the ink storage unit and the ejection port, which corresponds to the ink with the smallest static surface tension (mN / m) among the cyan ink, magenta ink, and yellow ink, is the longest. If bubbles are mixed into the ink passing through the ink flow path, the ejection is likely to be affected. And, the longer the ink flow path from the ink storage unit to the ejection port, the more bubbles are likely to be mixed in. By minimizing the static surface tension of the ink flowing through the ink flow path with the longest horizontal portion, the wettability of the ink to the ink flow path is increased, making it difficult for bubbles to be generated, and making it easier to make the amount of bubbles generated the same as the other two colors. This makes it possible to eject the three colors of ink more uniformly, and the uniformity of the recorded image can be further improved.

[0049] Among the static surface tensions of the cyan ink, magenta ink, and yellow ink, the static surface tension of the ink with the smallest lightness is "γs1 (mN / m)" and the static surface tension of the ink with the largest lightness is "γs2 (mN / m)". In this case, the difference (γs1-γs2) between the "static surface tension γs1 (mN / m) of the ink with the smallest lightness" and the "static surface tension γs2 (mN / m) of the ink with the largest lightness" is preferably 0.0 mN / m or more and 2.0 mN / m or less. When inks of different hues are applied adjacent to each other on a recording medium, the inks may partially mix at the boundary, causing the boundary to bleed and reducing the quality of the image. In particular, when two types of inks with a large lightness difference are applied adjacent to each other on a recording medium, the bleed at the boundary is easily noticeable. In addition, at the boundary, the ink with the high static surface tension tends to easily draw in the ink with the low static surface tension. Therefore, by setting "γs1-γs2" within the above range, it is possible to print images with less bleeding and with higher quality.

[0050] [Dynamic surface tension] As described above, in the inkjet recording apparatus of this embodiment, a plurality of ejection ports are arranged in parallel with the longitudinal direction of the ink storage section, and three ejection port arrays corresponding to cyan ink, magenta ink, and yellow ink are formed in the recording head. Among the three ejection port arrays, the ink corresponding to the ejection port array arranged in the center has the smallest dynamic surface tension γ10 (mN / m) at 25°C and a life time of 10 milliseconds. Ink with a small dynamic surface tension value at a life time of 10 milliseconds tends to penetrate quickly when applied to a recording medium. If the dynamic surface tension value of the ink corresponding to the ejection port array arranged in the center among the three ejection port arrays is minimized, the ink will penetrate quickly into the recording medium even if it mixes with ink ejected from the ejection ports of the ejection port arrays arranged on both sides. Therefore, bleeding at the boundary can be further suppressed. The dynamic surface tension of the ink at 25°C is preferably 35.0 mN / m or more and 55.0 mN / m or less.

[0051] The static surface tension of the ink can be measured by the Wilhelmy method (plate method). The static surface tension of the ink can be appropriately adjusted, for example, by setting the type and amount of the water-soluble organic solvent and surfactant. The dynamic surface tension of the ink can be measured by the maximum bubble pressure method. The dynamic surface tension of the ink can be appropriately adjusted, for example, by setting the type and amount of the water-soluble organic solvent.

[0052] 〔brightness〕 As described above, when three nozzle rows corresponding to cyan ink, magenta ink, and yellow ink are formed on the print head, the three nozzle rows are preferably arranged in the order of the brightness of the corresponding ink. An image is printed by applying ink ejected from the nozzles of the nozzle rows on both sides to the print medium so as to fill in the brightness difference with respect to the ink ejected from the nozzles of the nozzle row arranged in the center. As a result, even if bleeding occurs, the brightness difference is reduced and is less noticeable, making it possible to print a higher quality image.

[0053] The ink brightness is determined by the L standard set by the CIE (International Commission on Illumination). * a * b * L in the display system * The brightness can be measured using a spectrophotometer by diluting the ink with water to an appropriate ratio so that the absorbance value is suitable for measurement. The brightness of the ink may vary depending on the content of the coloring material in the ink. For this reason, when comparing the brightness of multiple inks, the multiple inks can be diluted with water to the same ratio. The brightness of the ink can be adjusted as appropriate by setting the type and amount of dye.

[0054] [pH] The pH of the ink at 25° C. is preferably 5.0 or more and 9.5 or less. The pH of the ink can be appropriately adjusted by a pH adjuster, etc. The pH of the ink tends to be easily affected by the counter ion of the ionic group of the water-soluble dye. EXAMPLES

[0055] 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.

[0056] <Preparation of dye solution> As dyes, CI Direct Blue 199, CI Acid Blue 9, CI Acid Red 249, CI Direct Yellow 132, Compound 1, Compound 2, and Compound 3 were prepared. The prepared dyes were dissolved in pure water to prepare aqueous solutions of each dye with a dye content of 10.00%. Details of Compound 1, Compound 2, and Compound 3 are shown below.

[0057] (Compound 1) According to the description of JP-A-10-306221, a sodium salt of a compound represented by the following formula (1) in free acid form (Compound 1) was obtained.

[0058] TIFF2025024683000002.tif53170

[0059] (Compound 2) According to the description of JP 2006-143989 A, a sodium salt of a compound represented by the following formula (2) in free acid form (Compound 2) was obtained.

[0060] TIFF2025024683000003.tif76170

[0061] (Compound 3) According to the description of JP2012-149212A, a potassium salt of a compound represented by the following formula (3) in free acid form (Compound 3) was obtained.

[0062] TIFF2025024683000004.tif51170

[0063] <Ink Preparation> (Inks C1-C9, M1-M4, Y1-Y3) Each ink was prepared by mixing the components (unit: %) shown in the upper part of Tables 1-1 and 1-2, thoroughly stirring, and then filtering under pressure through a filter with a pore size of 0.20 μm. In Tables 1-1 and 1-2, "Acetylenol E100" and "Acetylenol E60" are both trade names for acetylene glycol-based nonionic surfactants (manufactured by Kawaken Fine Chemicals).

[0064] The properties of each ink are shown in the lower part of Tables 1-1 and 1-2. The viscosity of the ink was measured at a temperature of 25°C using a rotational viscometer (product name "RE80 type viscometer", manufactured by Toki Sangyo Co., Ltd.). The static surface tension γs of the ink was measured at a temperature of 25°C using an automatic surface tensiometer (product name "DY-300", manufactured by Kyowa Interface Science Co., Ltd.). The dynamic surface tension γ10 of the ink at a life time of 10 milliseconds was measured at a temperature of 25°C using a dynamic surface tensiometer based on the maximum bubble pressure method (product name "BUBBLE PRESSURE TENSIOMETER BP-2", manufactured by KRUSS Co., Ltd.). The brightness of the ink was measured using an ultraviolet-visible spectrophotometer (product name "U-3900H", manufactured by Hitachi, Ltd.) under the conditions of light source: C and field of view: 2° after diluting the ink 2,000 times with pure water. The brightness of the ink was measured using the L * a * b * Lightness L based on the display system * It is.

[0065] TIFF2025024683000005.tif124170

[0066] TIFF2025024683000006.tif142170

[0067] (Ink C10, M5, Y4) In accordance with the description of Patent Document 2, the components (unit: %) shown in the upper part of Table 2 were mixed, thoroughly stirred, and then pressure filtered through a filter with a pore size of 0.20 μm to prepare each ink. The inks in Table 2 correspond to inks C1, M1, and Y1 described in Patent Document 2. In Table 2, "Acetylenol E100" is the trade name of an acetylene glycol-based nonionic surfactant (manufactured by Kawaken Fine Chemicals). The properties of each ink are shown in the lower part of Table 2. The measurement conditions were the same as those for the inks described in Tables 1-1 and 1-2.

[0068] TIFF2025024683000007.tif123170

[0069] <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 4.5 ng. A thermoplastic resin composition was molded to obtain recording units 1 to 13 having storage portions arranged in the manner shown in Figs. 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 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. An ink flow path through which ink flows between the ink storage portion and the ejection port was formed so that the ink storage portions a to c shown in Figs. 7A to 7E and the positions of the ink storage portions corresponding to each of the ejection port arrays (left side, center, and right side) are in the relationship shown in Table 3.

[0070] 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 perpendicular 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 9, 10, and 12 shown in Table 3 were obtained by molding a thermoplastic resin that is a mixture of a styrene-based resin and polyphenylene ether, that is, a thermoplastic resin to which no filler material is added. A recording unit was manufactured by bonding a recording head to the obtained ink storage section without interposing any other member.

[0071] TIFF2025024683000008.tif107170

[0072] <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 4.5 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 unacceptable levels. The evaluation results are shown in Table 4. In Table 4, the symbols (a to c) indicating the positions of each color ink correspond to the symbols (a to c) in FIGS. 7A to 7E.

[0073] (Strength of ink storage section) To promote thermal deformation of the ink storage part (housing), the recording unit was stored in an environment at 60°C for one month and two months. 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: Even after storing at 60°C for two months, no cracks or chips occurred in the ink storage area. B: No cracks or chips occurred in the ink storage section after storage at 60°C for one month, but cracks and chips occurred in the ink storage section after storage at 60°C for two months. C: After storage at 60°C for one month, cracks and chips occurred in the ink storage area.

[0074] (Image bleed) Using the above-mentioned inkjet recording device, solid images of cyan, magenta, and yellow inks with a recording duty of 100% were recorded adjacently on a recording medium. In other words, this image includes three adjacent portions. Glossy paper (product name "Canon Photo Paper Glossy Gold GL-101", manufactured by Canon) was used as the recording medium. The adjacent portions of the recorded solid images were visually inspected, and the bleeding of the image was evaluated according to the following evaluation criteria. A: No bleeding was observed in any adjacent areas of the image. B: There was one adjacent area where bleeding was observed. C: Bleeding was observed in two or more adjacent areas.

[0075] (Image uniformity) Using the above-mentioned inkjet recording device, a three-color solid image with a recording duty of 33% was recorded on the entire surface of an A4-sized recording medium. The recording medium used was glossy paper (product name "Canon Photo Paper Gloss Gold GL-101", manufactured by Canon), and recording was performed under the condition of "Full borderless recording off." Both ends of the recorded solid image were visually inspected, and the uniformity of the image was evaluated according to the evaluation criteria shown below. A: All three solid color images were uniform with no color unevenness observed. B: Color unevenness was observed in a solid image of one color. C: Color unevenness was observed in a solid image of two or more colors.

[0076] (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.

[0077] TIFF2025024683000009.tif200170

Claims

1. an inkjet recording device is used, the inkjet recording device comprising: an aqueous ink containing a dye; an ink storage section for storing the aqueous ink and formed of a thermoplastic resin composition containing a filler material; and a recording head, which is bonded to the ink storage section and has an ejection port array formed therein 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 port array to a recording medium to record an image, the ink storage section has three or more storage sections that are mutually independent and divided by partitions that are arranged perpendicular to the longitudinal direction of the ink storage section, and the storage sections are arranged in a predetermined direction; the water-based inks include a cyan ink, a magenta ink, and a yellow ink; three rows of the ejection openings corresponding to the cyan ink, the magenta ink, and the yellow ink, respectively, are formed in the recording head along a longitudinal direction of the ink containing section, an ink jet recording method, characterized in that, among the dynamic surface tensions γ10 of the cyan ink, the magenta ink, and the yellow ink over a lifetime of 10 milliseconds, the dynamic surface tension γ10 of the ink corresponding to the ejection port array located in the center of the three ejection port arrays over a lifetime of 10 milliseconds is the smallest.

2. the inkjet recording apparatus further comprises an ink flow path including a horizontal portion through which the water-based ink flows between the ink storage unit and the ejection port, 2. The ink jet recording method according to claim 1, wherein the length of the horizontal portion corresponding to the ink having the smallest static surface tension (mN / m) among the cyan ink, the magenta ink, and the yellow ink is the longest.

3. 2. The ink jet recording method according to claim 1, wherein the ink having the largest dye content among the cyan ink, the magenta ink, and the yellow ink is contained in the containing portion disposed on the inside.

4. 2. The inkjet recording method according to claim 1, wherein a difference (η1-η2) between a maximum viscosity η1 (mPa·s) and a minimum viscosity η2 (mPa·s) of the viscosities of the cyan ink, the magenta ink, and the yellow ink is 0.2 mPa·s or less.

5. 2. The inkjet recording method according to claim 1, wherein a difference (γs1-γs2) between a static surface tension γs1 (mN / m) of an ink having the smallest lightness and a static surface tension γs2 (mN / m) of an ink having the largest lightness among the static surface tensions of the cyan ink, the magenta ink, and the yellow ink is 0.0 mN / m or more and 2.0 mN / m or less.

6. 6. The ink jet recording method according to claim 1, wherein the three ejection port arrays are arranged in order of the lightness of the corresponding inks.

7. 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 4.4 times or less.

8. 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.

9. 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.

10. An inkjet recording device comprising: an aqueous ink containing a dye; 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 array for ejecting the aqueous ink supplied from the ink storage section, the ink storage section has three or more storage sections that are mutually independent and divided by partitions that are arranged perpendicular to the longitudinal direction of the ink storage section, and the storage sections are arranged in a predetermined direction; the water-based inks include a cyan ink, a magenta ink, and a yellow ink; three rows of the ejection openings corresponding to the cyan ink, the magenta ink, and the yellow ink, respectively, are formed in the recording head along a longitudinal direction of the ink containing section, An inkjet recording device characterized in that, among the dynamic surface tensions γ10 of the cyan ink, the magenta ink, and the yellow ink over a lifetime of 10 milliseconds, the dynamic surface tension γ10 of the ink corresponding to the ejection port array located in the center of the three ejection port arrays over a lifetime of 10 milliseconds is the smallest.

Images