Recording apparatus, recording method, and ink composition

Abstract

To provide a recording apparatus having excellent visibility of an ink liquid level and initial filling properties.SOLUTION: A recording apparatus has an ink container, an ink supply part, an inkjet head, and an ink composition, where the ink container has an ink inlet to which the ink composition is injected, and a liquid level display part which displays an ink liquid level of the ink composition housed in the ink container, the inkjet head, after being supplied with the ink composition from the ink container via the ink supply part, ejects the ink composition to be attached on a recording medium, the ink composition is aqueous red-based ink containing azo-based pigment, acetylene glycol-based surfactant A having an HLB value of less than 10, and acetylene glycol-based surfactant B having an HLB value of 10 or more.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] 2. Description of the Related Art Inkjet recording apparatuses are known that record images or the like on a recording medium by ejecting minute ink droplets from nozzles of a recording head for inkjet recording. In addition, with the increase in remote work and SOHO, the number of opportunities to use inkjet recording devices at home and elsewhere is also increasing. An inkjet recording apparatus has an ink container (such as an ink cartridge) for supplying an ink composition to a recording head.

[0003] Known examples of such ink containers include a type in which the ink container itself is replaced when the ink composition inside the ink container falls below a certain amount (so-called ink cartridges), and a type in which the ink composition is replenished inside a continuous supply ink container without replacing the ink container (so-called continuous supply ink containers).

[0004] For example, Patent Document 1 describes an ink composition that is injected into an ink container having an ink chamber that can be refilled with the ink composition and an ink inlet that can be opened and closed, and the ink chamber can be communicated with the outside air, the ink composition containing a pigment, a resin, and an organic solvent, and having a static contact angle of 10° or more with a member that constitutes the inside of the wall that divides the ink chamber. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-061896 A Summary of the Invention [Problem to be solved by the invention]

[0006] An example of the ink container is the above-mentioned continuous supply ink container (also referred to as a CISS tank in this specification). A CISS tank has the advantage that it allows continuous printing without the trouble of replacing ink cartridges. In addition, there is no need to use an ink cartridge every time an ink cartridge is replaced, and it is sufficient to only refill the ink container with ink. However, although a CISS tank may have a liquid level indicator for checking the remaining amount of ink, the visibility of the liquid level indicator may be impaired by ink adhering to the wall surface. On the other hand, when filling a printer with ink for the first time, air bubbles may get into the inkjet head and impair the filling ability. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by using an inkjet recording apparatus having a specific configuration, thereby completing the present invention.

[0008] The present invention is as follows. The recording apparatus of the present invention is a recording apparatus having an ink container, an ink supply unit, an inkjet head, and an ink composition, the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates an ink liquid level of the ink composition contained in the ink container, the inkjet head receives the ink composition from the ink container via the ink supply unit, and ejects the ink composition onto a recording medium; The ink composition is a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more. The recording method of the present invention is a recording method performed by using a recording apparatus having an ink container, an ink supply unit, and an inkjet head, a supplying step of supplying an ink composition from the ink container to the inkjet head via the ink supply unit; a deposition step of ejecting the ink composition from the inkjet head and depositing the ink composition on a recording medium, the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates an ink liquid level of the ink composition contained in the ink container, The ink composition is a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more. The ink composition of the present invention is an ink composition for use in recording with a recording apparatus having an ink container, an ink supply unit, and an inkjet head, the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates an ink liquid level of the ink composition contained in the ink container, the inkjet head receives the ink composition from the ink container via the ink supply unit, and ejects the ink composition onto a recording medium; This is a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more. [Brief description of the drawings]

[0009] [Figure 1] 1 is a table showing the results of the examples. [Diagram 2] 1 is a table showing the results of the examples. [Diagram 3] 1 is a table showing the results of the examples. [Figure 4] FIG. 1 is a schematic diagram of an example of an inkjet recording apparatus according to an embodiment of the present invention. [Diagram 5] FIG. 4 is a schematic diagram of another example of the inkjet recording apparatus of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the "present embodiment"). However, the present invention is not limited to this embodiment, and various modifications are possible without departing from the gist of the present invention.

[0011] 1. Recording device The recording apparatus of the present embodiment is a recording apparatus having an ink container, an ink supply unit, an inkjet head, and an ink composition, wherein the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates the ink liquid level of the ink composition contained in the ink container, the ink supply unit supplies the ink composition from the ink container to the inkjet head, and the inkjet head receives the ink composition from the ink container via the ink supply unit and ejects the ink composition to deposit it on a recording medium, and the ink composition is a water-based red ink containing an azo pigment, an acetylene glycol-based surfactant A having an HLB value of less than 10, and an acetylene glycol-based surfactant B having an HLB value of 10 or more.

[0012] Conventionally, inks containing quinacridone pigments have been known as red inks such as magenta inks. However, inks containing quinacridone pigments may have insufficient color development and ink level visibility. Therefore, the present inventors have considered that the visibility of the ink level can be improved by adopting a red ink containing an azo pigment (red) with good color development. However, it was found that red inks containing azo pigments (red) have good color development properties, and once the ink adheres to the inner wall surface of the liquid level indicator, it impedes the visibility of the ink level, making it actually more difficult to see the liquid level. When ink is poured into the ink container, ink may adhere to the inner wall of the ink container. This is because the ink may splash or bubble during the pouring process. In addition, ink may adhere to the inner wall of the ink level indicator due to the shaking of the ink container. Furthermore, when ink is consumed and the ink level drops, the ink that was adhered to the inner wall of the ink level indicator remains. In these cases, if the ink has good runoff properties, the ink will run off the inner wall surface of the liquid level indicator quickly and will not stick to the surface. However, if the ink has poor runoff properties, the ink will run off the inner wall surface of the liquid level indicator slowly, and ink will remain stuck to the surface. Furthermore, if the ink flows slowly, the ink dries before it flows down, reducing its fluidity and making it even more difficult for the ink to flow down, which reduces the visibility of the ink level on the ink level indicator. The recording apparatus of this embodiment includes the above-mentioned configuration, and thus has excellent visibility of the ink level and excellent initial filling performance.

[0013] 1.1.Ink container The recording apparatus of this embodiment has an ink container. The ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that displays the ink liquid level of the ink composition contained in the ink container.

[0014] Unless otherwise specified, the ink container in this embodiment is not limited in shape. For example, in an ink container for each color (e.g., a CISS tank), the height from the ink inlet to the bottom may vary depending on the design or layout of the ink container. For example, an ink container may have a high height from the ink inlet to the bottom. For example, when ink containers are stacked in two layers to make the lateral length of the printer compact, an ink container with a height equivalent to two normal ink containers may be provided. Alternatively, when using an ink container with a large capacity, the width of the ink container in the lateral direction may be increased. When it is not desirable to increase the width of the ink container in the lateral direction from the viewpoint of layout, the height of the ink container may be increased. In that case, the height from the fill port to the tank bottom may be different in the CISS tank for each color. In addition, the CISS tanks for each color may be freely laid out so that they have the same capacity but different heights.

[0015] The ink inlet is an inlet for injecting the ink composition in order to fill the ink container with the ink composition. The ink composition injected from the ink inlet is contained in the ink container. When the ink composition is contained in the ink container, the ink level can be visually confirmed from the ink level indicator.

[0016] The liquid level indicator displays the ink level of the ink composition contained in the ink container, thereby allowing the remaining amount of the ink composition to be confirmed. Since the ink level indicator is included in the ink container, the material of the ink level indicator and the material of the ink container may be the same. The materials of the ink level indicator and the ink container are the materials of the inner parts that come into contact with the ink. The material of the liquid level indicator is not particularly limited, but is preferably a thermoplastic resin, more preferably a polyolefin, and more preferably polypropylene for the material of the inner wall of the liquid level indicator. The liquid level indicator is not particularly limited, and may be, for example, a transparent or semi-transparent resin, glass, etc. The liquid level indicator allows a user to visually check the ink liquid level of the ink composition contained in the ink container from outside the ink container.

[0017] The ink container has a volume of 10 cm to suppress foaming and improve initial filling. 3 ~500cm 3 It is preferable that the 3 ~400cm 3 It is preferable that the 3 ~300cm3 It is preferable that:

[0018] Specifically, the ink container may have the following configuration. The ink container supplies the ink composition to the inkjet head through the ink supply section. The ink container may have an ink inlet provided at the top and a liquid container section communicating with the ink inlet and the outside air. A user can inject the ink contained in the ink bottle into the ink container by inserting the refill port of the ink bottle into the ink inlet of the ink container. In other words, the ink container is preferably a so-called continuous supply type ink container in which ink is refilled from the outside without replacing the ink container even when the ink contained in the ink container runs out. Since the problem of foaming of the ink composition often occurs especially when refilling the ink, the inkjet recording device of this embodiment preferably has a continuous supply type ink container that allows refilling of the ink. A continuous supply type ink container that has an ink inlet through which the ink composition is injected and that can continuously supply ink to the inkjet head is called a CISS tank.

[0019] Inkjet printers equipped with such a continuous supply type ink container that allows ink to be replenished are often used in offices, small businesses, and the like to print characters and images on plain paper.

[0020] 1.2.Ink supply unit The recording apparatus of this embodiment has an ink supply unit. The ink supply unit supplies the ink composition from the ink container to the inkjet head. Specifically, the ink supply unit is, for example, an ink supply pipe or an ink tube, and is a component that distributes ink from the ink container to the inkjet head so that the ink is supplied from the ink container to the inkjet head. The ink container and the inkjet head are connected by an ink supply unit. The ink may be circulated by using a negative pressure or a height difference generated by ejecting the ink from the inkjet head, or by using a liquid delivery mechanism such as a pump.

[0021] 1.3.Inkjet head The recording apparatus of this embodiment has an inkjet head. The inkjet head receives the ink composition from the ink container via the ink supply unit, and ejects the ink composition to deposit it on a recording medium. The inkjet head has a nozzle surface provided at a position facing the recording surface of the recording medium, and may eject ink in the form of droplets from a plurality of nozzles provided on the nozzle surface to deposit the ink on the recording surface of the recording medium.

[0022] The inkjet head may be a line head or a serial head. In the line method using a line head, the head is fixed and the recording medium is moved along the sub-scanning direction (the vertical direction of the recording medium, the transport direction), and ink droplets are ejected from the nozzle openings of the head in conjunction with this movement to record an image on the recording medium. A line printer, which is an inkjet recording device using the line method, is equipped with a line head that is at least as long as the width of the recording medium. On the other hand, in the serial method using a serial head, the head is moved along the main scanning direction (horizontal direction, width direction of the recording medium) and ink droplets are ejected from the nozzle openings of the head in conjunction with this movement, thereby recording an image on the recording medium. A serial printer, which is an inkjet recording device using the serial method, performs a main scan (pass) in which the head ejects the ink composition while moving in the main scanning direction intersecting with the sub-scanning direction of the recording medium, and usually performs recording in two or more passes (multi-pass).

[0023] The inkjet head has a cavity for ejecting the stored ink composition from a nozzle, an ejection driving unit provided for each cavity for applying a driving force for ejection to the ink composition, and a nozzle provided for each cavity for ejecting the ink composition to the outside of the inkjet head. A single head may have a plurality of cavities, ejection driving units and nozzles provided for each cavity, each independent of one another. The ejection driving unit may be formed using an electromechanical conversion element such as a piezoelectric element that changes the volume of the cavity by mechanical deformation, or an electrothermal conversion element that generates heat to generate bubbles in the ink and eject it.

[0024] The inkjet recording device may be provided with one or more heads for each color of ink.

[0025] 1.4. Ink composition The inkjet recording apparatus of this embodiment has an ink composition (also simply referred to as "ink"). At least one of the ink compositions is a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more.

[0026] The ink composition in this embodiment may be designed to satisfy required characteristics based on the structure and properties of the recording apparatus, ink container, and the like. Components that may be contained in the ink composition (hereinafter simply referred to as "ink") in this embodiment will be described below.

[0027] 1.4.1. Azo pigments The ink composition of this embodiment contains an azo pigment. Examples of the azo pigment include a monoazo pigment, a disazo pigment, a condensed disazo pigment, and a benzimidazolone pigment. Among azo pigments, a pigment capable of producing red-based colors is used.

[0028] For example, an azo pigment that can produce an ink-jet ink composition as a red ink can be used, such as an azo pigment designated with the number CI Pigment Red. Specific examples of such azo pigments include CI Pigment Red 5, CI Pigment Red 17, CI Pigment Red 22, CI Pigment Red 31, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 146, CI Pigment Red 150, CI Pigment Red 185, CI Pigment Red 114, CI Pigment Red 146, CI Pigment Red 150, CI Pigment Red 170, CI Pigment Red 184, CI Pigment Red 185, CI Pigment Red 208, CI Pigment Red 245, CI Pigment Red 268, CI Pigment Red 269, and solid solutions thereof.

[0029] Among the above, from the viewpoint of obtaining an image with more excellent color development, the azo pigment is preferably one or more selected from the group consisting of CI Pigment Red 150, CI Pigment Red 269, and CI Pigment Red 17.

[0030] From the viewpoint of obtaining an image with even better color development, the azo pigment is preferably a compound represented by the following formula (I) or a solid solution thereof.

[0031] [ka]

[0032] (In formula (I), A represents a hydrogen atom or an aromatic group.)

[0033] Here, the aromatic group is a group having an aromatic ring such as a benzene ring or a naphthalene ring, and the aromatic ring can be substituted or unsubstituted. In addition, the aromatic ring is directly bonded to the nitrogen atom to which the aromatic group is bonded. Furthermore, when the aromatic ring has a substituent, the substituent is not particularly limited, and is, for example, an organic group or an inorganic group, and the number of the substituent can be selected arbitrarily. The substituent is not limited, but examples thereof include an alkyl group, a halo group, an alkoxy group, a hydroxyl group, a carboxyl group, an amino group, and a nitro group.

[0034] The azo pigment may be a resin-dispersed pigment dispersed in a resin, or a self-dispersed pigment in which a functional group has been introduced by treating the pigment surface. Resin-dispersed pigments are preferred.

[0035] The volume average particle diameter D50 of the azo pigment is preferably 110 nm or less. The volume average particle diameter D50 of the azo pigment can be measured by a particle size distribution measuring device. Examples of the particle size distribution measuring device include a particle size distribution meter using dynamic light scattering as the measurement principle (for example, the "Nanotrack Series" manufactured by Microtrack Bell). The volume average particle diameter is the D50 value.

[0036] The volume average particle size of the azo pigment is preferably 10 nm or more and 110 nm or less, more preferably 50 nm or more and 110 nm or less, even more preferably 80 nm or more and 110 nm or less, even more preferably 80 nm or more and less than 110 nm, and especially preferably 80 nm or more and 100 nm or less.

[0037] By setting the volume average particle size of the azo pigment within the above range, the pigment has good dispersion stability and better color development, and sedimentation of the components during storage is further suppressed.

[0038] The volume average particle size of the azo pigment may be adjusted, for example, by adjusting the degree of pulverization, such as the intensity and time of pulverization, in the pulverization step in which the pigment particles are pulverized. Alternatively, the volume average particle size may be adjusted by adjusting the intensity and time of stirring in the dispersion step in which the pigment particles are dispersed in a dispersion liquid. Alternatively, the particle size of the pigment may be adjusted by classifying the particles using a filter after pulverization or dispersion.

[0039] The ink composition of the present embodiment contains the above-mentioned azo pigment, and thus can be made into an ink with excellent color development. Therefore, the amount of ink attached to obtain excellent color development can be reduced. Therefore, the ink is consumed less, and the ink tends to remain contained in the ink container for a long period of time. Even in such a case, by setting the volume average particle diameter of the azo pigment within the above range, the pigment has good dispersion stability and better color development, and sedimentation of the components during storage is further suppressed.

[0040] The content of the azo pigment is preferably 1.0% by mass to 8.0% by mass, more preferably 3.0% by mass to 7.5% by mass, and even more preferably 4.0% by mass to 7.0% by mass, relative to the total amount of the ink composition. When the content of the azo pigment falls within this range, an image with even better color development can be obtained.

[0041] The ink composition may contain a pigment other than an azo pigment. The content of the azo pigment is preferably 70% by mass or more, 80% by mass to 100% by mass, or 90% by mass to 100% by mass, based on the total amount of pigments.

[0042] The ink composition of the present embodiment is a water-based red-based ink. The red-based ink is an ink that is mainly used to express the color red when printing is performed to reproduce secondary or higher colors using multiple color inks. For example, the ink is a magenta ink, a red ink, or an ink similar thereto.

[0043] The red ink is preferably a magenta ink. Here, the magenta ink generally means an ink used as an ink set together with a cyan ink, a yellow ink, and, if necessary, a black ink. For example, it includes ink generally named magenta ink in commercially available ink cartridges and inks generally associated with magenta ink.

[0044] Red refers to a color whose hue angle is within a predetermined range in the L*a*b* color system standardized by the CIE (International Commission on Illumination). The hue angle of red is preferably 5° to 60°, more preferably 15° to 50°, and even more preferably 25° to 40°. Red inks are inks that are primarily used when printing red. Preferably, the ink is capable of expressing the red color by itself.

[0045] The recording apparatus of this embodiment can also use inks other than the ink composition described above. The recording apparatus of this embodiment preferably further includes cyan ink, yellow ink, and black ink. In this case, the recording apparatus of this embodiment preferably includes an inkjet head C that ejects the cyan ink, an inkjet head Y that ejects the yellow ink, and an inkjet head B that ejects the black ink. The cyan ink, yellow ink and black ink contain coloring materials having the color development properties of cyan, yellow and black, respectively.

[0046] Surfactants The ink in this embodiment contains an acetylene glycol surfactant A having an HLB value of less than 10 and an acetylene glycol surfactant B having an HLB value of 10 or more. The surfactant has the function of reducing surface tension and improving wettability with a recording medium. In this specification, the term "HLB value" refers to a value defined by the Griffin method.

[0047] By including acetylene glycol surfactant A, the initial filling property of the ink in the recording device is improved. If air bubbles remain in the ink flow path or the components inside the head during initial filling of the ink (first filling, filling when the ink is empty), the air bubbles will cause poor ejection of the ink composition. The low HLB acetylene glycol surfactant increases the wetting of the ink to the components inside the ink flow path or the head and suppresses the remaining of air bubbles, thereby preventing poor ejection of the ink composition (initial filling property).

[0048] On the other hand, this increases the ink's wettability to the components, and when the ink adheres to the tank wall, it may not flow well and the visibility of the ink level may be impaired. In addition, acetylene glycol surfactant A increases the ink's foaming property, making it easier to foam. This makes it easier for bubbles to form when the ink is filled into the tank, which can cause the ink to spill from the tank. The bubbles also cause the ink to adhere to the tank wall.

[0049] Therefore, in this embodiment, in addition to the acetylene glycol surfactant A, an acetylene glycol surfactant B is used in combination. This improves the ink flow off the tank wall surface, further improving the visibility of the liquid level. In addition, the acetylene glycol surfactant B suppresses the ink wettability, improves the ink flow off, and further improves visibility. In addition, the acetylene glycol surfactant B suppresses ink foaming.

[0050] An example of the acetylene glycol surfactant is an acetylene glycol surfactant represented by the following formula (1).

[0051] [ka]

[0052] (In formula (1), R 1 , R 2 , and R 3each independently represents an alkyl group having 1 to 6 carbon atoms, and m, n, p, and q each independently represent an integer of 0 to 50. R 1 , R 2 , and R 3 is not particularly limited, but examples thereof include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, and tert-butyl. R 3 is preferably a methyl group.

[0053] The acetylene glycol surfactant A includes, for example, an acetylene glycol surfactant represented by formula (1), preferably one in which n+p and m+q in formula (1) are each independently 0 to 30. More preferably, n+p and m+q are each independently 15 or less, more preferably 10 or less, and even more preferably 5 or less. Furthermore, in formula (1), n+p+m+q is preferably 0 to 30, more preferably 15 or less, further preferably 10 or less, and particularly preferably 5 or less. Further, an acetylene glycol surfactant in which n, m, p and q are each 0 in the formula (1) is more preferred. Among these, for example, polyoxyethylene (4) acetylenic glycol ether, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and 2,4,7,9-tetramethyldec-5-yne-4,7-diol are preferably used. By including such a surfactant, the initial filling property tends to be improved.

[0054] The acetylene glycol surfactant B is preferably an alkylene oxide adduct of acetylene glycol. For example, in formula (1), n+p and m+q are each independently 1 or greater. Further, for example, in formula (1), n+p and m+q are each independently 1 to 50. More preferably, n+p and m+q are each independently 6 to 30, more preferably 11 to 30, and even more preferably 16 to 30. Alternatively, in the formula (1), n+p+m+q is preferably 1 to 50, more preferably 6 to 30, further preferably 11 to 30, and particularly preferably 16 to 30. In formula (1), the smaller the number of alkylene oxides added, the smaller the HLB value tends to be, and the larger the number of alkylene oxides added, the larger the HLB value tends to be. Therefore, for example, in formula (1), the HLB value of the acetylene glycol surfactant can be adjusted by adjusting the number of alkylene oxides added. For example, n+p and m+q in formula (1) of acetylene glycol surfactant A may be smaller than n+p and m+q in formula (1) of acetylene glycol surfactant B.

[0055] Commercially available acetylene glycol surfactants include, but are not limited to, Surfynol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37, CT111, CT121, CT131, CT136, TG, and GA (all trade names, manufactured by Air Products and Chemicals, Inc.), Ol Examples of such polyolefins include Finn B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP.4001, EXP.4036, EXP.4051, EXP.4200, EXP.4300, AF-103, AF-104, AK-02, SK-14, and AE-3 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), and Acetylenol E00, E00P, E40, and E100 (all trade names, manufactured by Kawaken Fine Chemical Co., Ltd.). From the above, an acetylene glycol surfactant A having an HLB value of less than 10 and an acetylene glycol surfactant B having an HLB value of 10 or more can be appropriately selected. As the acetylene glycol surfactant A, Surfynol 104 and Surfynol SE-F are preferred. As the acetylene glycol surfactant B, Olfine E1010 and EXP.4200 are preferred.

[0056] The content of the acetylene glycol surfactant A is preferably 0.1% by mass to 0.8% by mass with respect to the total amount of the ink composition. The content of the acetylene glycol surfactant B is preferably 0.1% by mass to 0.8% by mass with respect to the total amount of the ink composition. When the contents of the acetylene glycol surfactants A and B are within the above ranges, the visibility of the ink amount and the initial filling property tend to be excellent. From the above viewpoints, the contents of the acetylene glycol surfactants A and B are each more preferably 0.2% by mass to 0.75% by mass, and even more preferably 0.3% by mass to 0.7% by mass, relative to the total amount of the ink composition. The ratio of the content of the acetylene glycol surfactant B to the content of the acetylene glycol surfactant A is preferably 0.1 to 10, 0.3 to 5, 0.5 to 2, or 0.8 to 1.5. The HLB value of the acetylene glycol surfactant A is less than 10, preferably 7 or less, more preferably 6 or less, and even more preferably 5 or less. The lower limit is 0 or more. The HLB value of the acetylene glycol surfactant B is 10 or more, preferably 11-20, more preferably 12-17, and even more preferably 13-15.

[0057] Resins The ink in this embodiment may contain resins such as resin particles, fixing resins, water-soluble resins, and pigment dispersant resins. The resin particles have a function of improving the adhesion of the ink adhered to the recording medium, and the pigment dispersant resin has a function of improving the dispersibility of the pigment.

[0058] The resin may be in any type, such as a dissolved state or a particulate state such as an emulsion. For example, when the resin is particulate (hereinafter also referred to as "resin particles"), the volume-based average particle diameter of the resin particles (hereinafter also simply referred to as "average particle diameter of resin particles") is preferably 30 nm or more and 300 nm or less, and more preferably 50 nm or more and 200 nm or less. When the average particle diameter of the resin particles is within the above range, there is a tendency for the fixation of the ink to the recording medium to be improved and for clogging of the filter or recording head to be reduced.

[0059] The average particle size of the resin particles can be measured by a particle size distribution measuring device that uses the laser diffraction scattering method as its measurement principle. For example, a particle size distribution meter that uses the dynamic light scattering method as its measurement principle (e.g., "Microtrack UPA" manufactured by Nikkiso Co., Ltd.) can be used as the particle size distribution measuring device.

[0060] Examples of resin particles that can be used include acrylic resins, fluorene resins, urethane resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, ethylene vinyl acetate resins, etc. These resin particles may be used alone or in combination of two or more. The acrylic resin may be a styrene acrylic resin. As the resin particles, commercially available products may be used, and examples thereof include Superflex (registered trademark) 420 (polyurethane water dispersion, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and X-436 (styrene acrylic resin emulsion, manufactured by Seiko PMC Corporation).

[0061] Examples of the pigment dispersant resin include polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylic acid ester copolymers, acrylic acid-acrylic acid ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers, styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinyl naphthalene-acrylic acid copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and the like, and salts thereof.

[0062] Among these, acrylic resins are preferred. Acrylic resins are a general term for polymers obtained by polymerizing at least acrylic monomers such as acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters as one component. For example, resins obtained from acrylic monomers, copolymers of acrylic monomers and other monomers, etc. can be mentioned. For example, acrylic-vinyl resins, which are copolymers of acrylic monomers and vinyl monomers, can be mentioned, for example, copolymers with vinyl monomers such as styrene. For example, styrene-acrylic resins can be mentioned.

[0063] Among these, a copolymer of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and a polymer made of a monomer having both a hydrophobic functional group and a hydrophilic functional group are preferred. The copolymer may be in any form of a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer.

[0064] The resin content, calculated as solid content, is preferably less than 100 parts by mass, preferably from 0.5 to 60 parts by mass, preferably from 1.0 to 50 parts by mass, and preferably from 2.0 to 40 parts by mass, relative to 100 parts by mass of the pigment contained in the ink. By having the resin content less than the pigment content, the formation of a resin film adhered to the recording medium is less likely to be inhibited by the pigment, which tends to improve the adhesion of the ink to the recording medium.

[0065] The total content of the resin and pigment is preferably 20% by mass or less, calculated as solid content, relative to the total mass of the ink (100% by mass). By keeping the total amount 20% by mass or less, the occurrence of aggregates in the ink can be reduced. The total content of the resin and the pigment is more preferably from 2% by mass to 15% by mass, from 3% by mass to 15% by mass, and from 3% by mass to 11% by mass.

[0066] Organic Solvents The ink in this embodiment may contain an organic solvent, preferably a water-soluble organic solvent. Examples of the organic solvent include alkanediols, polyhydric alcohols, glycol ethers, nitrogen-containing heterocyclic compounds, urea, urea derivatives, etc. These may be used alone or in combination of two or more.

[0067] Examples of alkanediols include 1,2-alkanediols having 4 to 8 carbon atoms (for example, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, etc.), 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 2-ethyl-1,3-hexanediol. Alkanediols have functions such as improving the wettability of the ink to a recording medium and suppressing drying and solidification of the ink on the nozzle surface of a recording head, etc. They can also improve the ink runoff property, and are preferable because they provide better visibility of the liquid surface.

[0068] When alkanediols are contained, the content thereof is, from the viewpoint of preventing the wettability from being excessively improved, preferably from 0.1% by mass to 20% by mass, more preferably from 0.5% by mass to 15% by mass, even more preferably from 0.7% by mass to 10% by mass, and particularly preferably from 1.0% by mass to 4.0% by mass, relative to the total amount of the ink composition.

[0069] Among the above alkanediols, it is preferable to use 1,2-alkanediols having 5 or 6 carbon atoms, because these compounds improve the permeability and wettability of the ink to the recording medium while causing only a small decrease in the surface tension of the ink.

[0070] Examples of glycol ethers include alkylene glycol monoethers and alkylene glycol diethers.

[0071] Examples of alkylene glycol monoethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether.

[0072] Examples of alkylene glycol diethers include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether.

[0073] The glycol ethers may be used alone or in combination of two or more. Glycol ethers are preferably used because they improve the permeability and wettability of the ink to the recording medium while causing little decrease in the surface tension of the ink. When glycol ethers are contained, the content thereof can be, for example, 0.05% by mass to 6% by mass based on the total mass of the ink. Furthermore, in order to appropriately control the wettability while taking into consideration the precipitation of aggregates, the content is preferably 0.2% by mass to 4% by mass.

[0074] Examples of polyhydric alcohols (excluding the above-mentioned alkanediols) include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,3-pentanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, trimethylolpropane, and glycerin. Polyhydric alcohols can be preferably used from the viewpoint of suppressing drying and solidification of the ink on the nozzle surface of the head, thereby reducing clogging and ejection failure. When polyhydric alcohols are contained, the content thereof can be, for example, 5% by mass or more, and further 5% by mass or more and 30% by mass or less, based on the total mass of the ink.

[0075] Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, N-butyl-2-pyrrolidone, 5-methyl-2-pyrrolidone, and hydantoin. Examples of urea or urea derivatives include urea, ethyleneurea, tetramethylurea, and thiourea. These can be used alone or in combination of two or more. These can be used preferably from the viewpoint of suppressing drying and solidification of the ink on the nozzle surface of the head and reducing clogging and ejection failure, as with polyhydric alcohols. When these are contained, the content can be, for example, 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less, based on the total mass of the ink.

[0076] Polyhydric alcohols, nitrogen-containing heterocyclic compounds, urea, and urea derivatives function as moisturizing agents. Among the above, by using glycerin in combination with one or more selected from the group consisting of polyhydric alcohols (above-mentioned polyhydric alcohols excluding glycerin), nitrogen-containing heterocyclic compounds, urea, and urea derivatives, both long-term water evaporation and rapid water evaporation on the wall surface of the ink chamber can be effectively suppressed. In this case, more preferred polyhydric alcohols are propylene glycol, dipropylene glycol, 1,3-butanediol, diethylene glycol, triethylene glycol, and trimethylolpropane. Among the polyhydric alcohols, propylene glycol, dipropylene glycol, diethylene glycol, and 1,3-butanediol are preferred from the viewpoint of preventing precipitation. In addition, as the nitrogen-containing heterocyclic compounds, pyrrolidone derivatives and hydantoin are preferred, and 2-pyrrolidone and hydantoin are more preferred. Furthermore, as the urea derivatives, ethyleneurea, tetramethylurea, and thiourea are preferred.

[0077] When the ink in this embodiment contains one or more selected from 1,2-alkanediols having 4 to 8 carbon atoms, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 2-ethyl-1,3-hexanediol, and glycol ethers, it is desirable to add a humectant that combines glycerin with one or more selected from the group consisting of other polyhydric alcohols (the above-mentioned polyhydric alcohols excluding glycerin), nitrogen-containing heterocyclic compounds, urea, and urea derivatives, from the viewpoint of preventing precipitation of aggregates. The total content of the organic solvents is preferably from 0.1% by mass to 30% by mass, more preferably from 1.0% by mass to 25% by mass, and even more preferably from 5% by mass to 20% by mass, based on the total amount of the ink composition.

[0078] 1.4.5. Lactam compounds The ink composition of this embodiment preferably contains a lactam compound. By including a lactam compound, it is possible to prevent precipitation, crystallization, and the like of impurities in the dispersion liquid of the azo pigment while maintaining the saturation of the azo pigment. As a result, the generation of foreign matter at the gas-liquid interface is effectively suppressed, and the ink tends to have excellent clogging recovery properties, ejection stability, re-dissolvability, and the like. In addition, acetylene glycol-based surfactant A has relatively low solubility in water, and when the ink dries in a nozzle or the like, it undergoes phase separation from the water, causing ejection problems. However, by containing a lactam compound, phase separation of the acetylene glycol-based surfactant A when the ink dries tends to be suppressed. In addition, the pigment and other components of the ink may dry and aggregate at the gas-liquid interface of the liquid surface of the CISS tank or at the nozzle, which may cause clogging, but by containing a lactam compound in the ink, the aggregation of the pigment is suppressed, redispersibility is improved, and clogging tends to be suppressed. In particular, since a gas-liquid interface occurs at the liquid surface of a CISS tank, foreign matter at the gas-liquid interface is a problem, so the present invention is particularly preferred. Furthermore, when ink adhering to the tank wall dries and the pigments coagulate, the ink sticks to the wall, making it difficult for the ink to flow off and reducing the visibility of the liquid level. However, if the ink contains a lactam compound, this can prevent the ink from becoming difficult to flow off, resulting in better visibility of the liquid level.

[0079] As the lactam compound, any lactam compound can be used without any particular limitation. Among the above-mentioned nitrogen-containing heterocyclic compounds, lactam compounds can also be used as the lactam compound. Lactam compounds having 4 to 7 membered rings are preferred, and lactam compounds having 5 to 7 membered rings are more preferred. Examples include 2-pyrrolidone, δ-lactam, 1-(2-hydroxyethyl)-2-pyrrolidone, ε-caprolactam, etc. 1-(2-hydroxyethyl)-2-pyrrolidone and ε-caprolactam are preferred.

[0080] The content of the lactam compound is preferably 0.1% by mass to 7.0% by mass, more preferably 0.3% by mass to 6.0% by mass, and even more preferably 0.5% by mass to 5.5% by mass, relative to the total amount of the ink composition. By ensuring that the content of the lactam compound is equal to or greater than the above lower limit, the generation of foreign matter at the gas-liquid interface is effectively suppressed, and clogging recovery, ejection stability, re-dissolvability, and the like tend to be excellent. By ensuring that the content of the lactam compound is equal to or less than the above upper limit, precipitation of the lactam compound can be suppressed, and clogging recovery properties and the like tend to be excellent.

[0081] 1.4.6.Water The ink in this embodiment may contain water. The ink in this embodiment is preferably an aqueous ink in which water is the main solvent of the ink and is a component that evaporates and scatters when dried. The water content of the aqueous ink is preferably 40% by mass or more, more preferably 50% by mass or more, relative to the total mass of the ink. Also, 60% by mass to 99% by mass is preferable.

[0082] Examples of water include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water from which ionic impurities have been removed as much as possible. Furthermore, the use of water that has been sterilized by, for example, ultraviolet irradiation or the addition of hydrogen peroxide can prevent the growth of mold and bacteria when the ink is stored for a long period of time.

[0083] Other For the purpose of improving the performance of the ink in this embodiment, wax particles (e.g., polyolefin wax, paraffin wax, etc.), zwitterionic compounds (e.g., betaine-based compounds, amino acids and their derivatives, etc.), sugars (e.g., glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, sorbitol, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, reduced starch saccharification products, etc.), sugar alcohols, hyaluronic acids, ureas, preservatives and fungicides (e.g., sodium benzoate, sodium pentachlorophenol, 2-pyridinyl ether, etc.), and the like are added. It may contain, for example, sodium zinthiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-dibenzinethiazolin-3-one, pH adjusters (for example, potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia, diethanolamine, triethanolamine, triisopropanolamine, potassium carbonate, sodium carbonate, sodium bicarbonate, etc.), chelating agents (for example, ethylenediaminetetraacetic acid and salts thereof (disodium dihydrogen ethylenediaminetetraacetate salt, etc.), antifoaming agents (SN Wet 980 (manufactured by San Nopco Ltd.)), etc.

[0084] One aspect of the ink composition of the present embodiment is an ink composition used for recording in a recording device having an ink container, an ink supply unit, and an inkjet head, the ink container having an ink inlet through which the ink composition is injected and a liquid level indicator that indicates the ink liquid level of the ink composition contained in the ink container, the inkjet head receiving a supply of the ink composition from the ink container via the ink supply unit and ejecting the ink composition to deposit it on a recording medium, the ink composition being a water-based red ink containing an azo pigment, an acetylene glycol-based surfactant A having an HLB value of less than 10, and an acetylene glycol-based surfactant B having an HLB value of 10 or more.

[0085] 4 is a perspective view showing an example of an inkjet recording apparatus according to the present embodiment. The inkjet recording apparatus 1 has an ink container 50 and an ink supply tube 24 that supplies ink from the ink container to the inkjet head 17. The ink supply tube 24 is an ink supply unit. The ink supply unit may be any unit that can circulate ink therethrough and supply ink from the ink container to the inkjet head, like the ink supply tube 24. It is a component that constitutes an ink supply path. A sub-tank 20 may be provided at a relay point between the ink container 50 and the inkjet head 17, and ink supplied via the ink supply path 24 may be temporarily stored in the sub-tank 20 and then supplied to the inkjet head 17. Alternatively, the sub-tank 20 may not be provided, and ink may be directly supplied from the ink container 50 to the inkjet head 17 via the ink supply pipe 24.

[0086] The inkjet head 17 ejects droplets of an ink composition (hereinafter also simply referred to as "ink") to record an image on a recording medium. It also has a carriage 16 that is mounted with a sub-tank 20 and an inkjet head 17 and can move back and forth in the X-axis direction, a paper feed port 12 that feeds the recording medium, a paper discharge port 14 that discharges the recording medium, and a support section 13 that supports the recording medium fed to the paper feed port 12. The inkjet head 17 has a nozzle surface (not shown) disposed opposite the recording surface of the recording medium, and ejects ink in the form of droplets from a plurality of nozzles (not shown) disposed on the nozzle surface to deposit the ink on the recording surface of the recording medium.

[0087] Inkjet recording methods that can be used include, for example, a method in which a strong electric field is applied between a nozzle and an accelerating electrode placed in front of the nozzle, causing ink droplets to be continuously ejected from the nozzle, and a printing information signal is applied to a polarizing electrode while the ink droplets fly between deflection electrodes to record; a method in which ink droplets are ejected in response to a printing information signal without being deflected (electrostatic attraction method); a method in which pressure is applied to the ink liquid with a small pump and ink droplets are forcibly ejected by mechanically vibrating the nozzle with a quartz oscillator or the like; a method in which pressure and a printing information signal are simultaneously applied to the ink with a piezoelectric element to eject and record ink droplets (piezo method); and a method in which the ink is heated and foamed with a microelectrode in accordance with the printing information signal to eject and record ink droplets (thermal jet method).

[0088] 4, for example, four sub-tanks 20Bk, 20Cn, 20Ma, and 20Yw are provided for each color of ink to correspond to the respective colors of ink contained in the ink container 50. There are also four inkjet heads 17 corresponding to the respective colors of ink. The carriage 16 carries the inkjet head 17 and the subtank 20, and is moved back and forth along the X-axis by a carriage movement mechanism (not shown) consisting of a motor, a timing belt, etc. As the carriage 16 moves, the inkjet head 17 also moves back and forth along the X-axis direction, so that an image is recorded on the recording medium in the X-axis direction by the ejection of ink from the inkjet head 17 as the carriage 16 moves. In this embodiment, a so-called serial head type inkjet recording device will be described as an example, but the present invention is not limited to this, and the ink container according to the present invention can also be applied to a so-called line head type inkjet recording device.

[0089] The paper discharge port 14 is provided on the front side of the inkjet recording device 1. The paper feed port 12 is provided on the rear side of the inkjet recording device 1. By setting a recording medium in the paper feed port 12 and performing a recording operation, the recording medium is fed from the paper feed port 12, and after an image or the like is recorded inside, the print paper is discharged from the paper discharge port 14. The recording medium can be transported by a paper feed mechanism (not shown) for feeding the paper in the Y-axis direction. In this way, the image can be recorded on the recording medium in the Y-axis direction by the ejection of ink from the inkjet head 17 accompanying the movement of the recording medium by the paper feed mechanism.

[0090] The inkjet recording device 1 has a control unit (not shown) that controls the overall operation of the inkjet recording device 1, and the control unit may include, for example, a CPU, a ROM, and a RAM. The control unit controls operations such as reciprocating the carriage 16, feeding the recording medium, ejecting ink from the inkjet head 17, and supplying ink from the ink container 50.

[0091] 4 shows the entire ink container 50, but inside it has a plurality of ink containers separated for each ink, and each ink has an ink supply path 24 and an ink inlet 54. When ink is not being injected, the ink inlet 54 is covered with a lid such as a cap (not shown), which can be opened and closed, and when ink is injected, the lid is opened to inject the ink.

[0092] The ink container 50 may be divided into a plurality of ink containers by dividing the inside of the ink container 50 with walls, or a plurality of ink containers may be arranged side by side, thus forming a plurality of ink containers for each ink. The positional relationship of the multiple ink containers is not limited, and they may be arranged, for example, in the vertical direction (Z direction) or horizontal direction (X direction or Y direction). When arranged in the vertical direction, the overall horizontal length of the ink containers is reduced, and thus the horizontal length of the inkjet recording device is reduced, which is preferable because it allows the installation area of ​​the inkjet recording device to be reduced. The positional relationship of the multiple ink inlets 54 is not limited, and they may be arranged in the vertical direction (Z direction) or horizontal direction (X direction or Y direction). If the heights of the ink inlets 54 in the vertical direction are uniform, it is easy to confirm the position of the ink inlet when injecting ink, and it is easy to inject ink, which is preferable. A liquid level indicator (not shown) is provided on the ink container 50. The liquid level indicator is provided, for example, on the front surface of the ink container 50 in the Y direction or on the left side surface in the X direction. 5 is a perspective view showing the inkjet head and the ink container of another example of the inkjet recording apparatus according to the present embodiment, which may be the same as the example shown in FIG. 4 except for the following description. The inkjet head 102 has a nozzle surface (not shown) disposed opposite the recording surface of the recording medium, and ejects ink in the form of droplets from a plurality of nozzles (not shown) disposed on the nozzle surface, causing the ink to adhere to the recording surface of the recording medium, thereby recording an image on the recording medium 101. The carriage 103 is capable of reciprocating motion to mount the inkjet head 102 and move it in the X-axis direction (main scanning direction). The carriage 103 is supported so as to be movable along a guide rail 105 arranged along the X direction, and is fixed to an endless belt 106 that moves in parallel with the guide rail 105. The endless belt 106 reciprocates due to the driving force of a motor, thereby causing the carriage 103 to scan back and forth in the X direction. The transport rollers 107 transport the recording medium 101 in a transport direction Y. The ink container 108 and the inkjet head 102 are connected by an ink supply unit 104 that distributes ink, and ink is supplied from the ink container 108 to the inkjet head 102 via the ink supply unit 104.

[0093] Although one ink container 108 is shown in the figure, it is sufficient if the ink container 108 is the same as the number of ink compositions contained in the inkjet recording apparatus. The same applies to the inkjet head 102. When there are two or more inkjet heads, the inkjets may be integrated or separate when viewed from the outside. The same applies to the ink container. The ink container 108 is provided with an ink inlet 109 for injecting ink from outside the inkjet recording apparatus into the ink container 108. The ink inlet 109 may be provided on the upper surface 201 of the ink container 108 or the like. When using the inkjet recording device for the first time, when the amount of ink is low, etc., ink is injected from an ink bottle or the like. The user can open the ink injection port 109 and inject ink into the ink container 108. The ink container 109 is left in the inkjet recording device and is not replaced by itself. A liquid level indicator 115 is formed on the side of the ink container 108, which allows the liquid level, which is the upper surface of the ink 110 contained in the ink container 108, to be visually confirmed.

[0094] 2. Recording method The recording method of the present embodiment is a recording method performed using the recording apparatus of the present embodiment, and includes a supplying step of supplying an ink composition from the ink container to the inkjet head via the ink supply unit, and an adhering step of ejecting the ink composition from the inkjet head and adhering it to a recording medium, wherein the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that displays the ink liquid level of the ink composition contained in the ink container, and the ink composition is a water-based red ink containing an azo pigment, an acetylene glycol-based surfactant A having an HLB value of less than 10, and an acetylene glycol-based surfactant B having an HLB value of 10 or more.

[0095] The inkjet recording apparatus of this embodiment has an ink container for supplying an ink composition to an inkjet head. There are no particular limitations on the mode in which the ink composition is supplied from the ink container to the inkjet head. For example, the inkjet head and the ink container may communicate with each other via a communication part (ink supply part), and the ink composition may be supplied from the ink container to the inkjet head via the communication part. Specifically, the following aspects may be adopted. One end of the liquid supply tube is connected to the ink container, and the other end is connected to the inkjet head. Ink contained in the ink container is supplied to the inkjet head via the liquid supply tube.

[0096] The recording method of the present embodiment includes a deposition step of ejecting the ink composition from an inkjet head and depositing it onto a recording medium. The inkjet method is not particularly limited, but examples thereof include a charge deflection method, a continuous method, and an on-demand method (piezo type, bubble jet (registered trademark) type).

[0097] In the recording method of the present embodiment, in the deposition step, cyan ink, yellow ink and black ink may be further ejected from other inkjet heads to be deposited on the recording medium.

[0098] The method may also include a step of injecting ink into the ink container. This step is a step of opening a cover of an ink inlet of the ink container and injecting ink into the ink container through the ink inlet to replenish the ink container with ink. For example, ink contained in an ink bottle may be poured from the ink bottle into the ink inlet.

[0099] When the ink injection is completed, the ink level of the ink composition is displayed on the ink level indicator, allowing the remaining amount of the ink composition to be confirmed.

[0100] 2.1. Recording medium The constituent material of the recording medium is not particularly limited, but examples include resin materials such as polyurethane, polyethylene, polypropylene, polyester, polyamide, and acrylic resin, paper, glass, metal, ceramics, leather, wood, pottery, and fabric. The constituent materials of the recording medium include at least one of the above fibers, various natural fibers such as silk, wool, cotton, hemp, polyester, polyamide (nylon), acrylic, polyurethane, cellulose, linter, rayon, cupra, acetate, synthetic fibers, and semi-synthetic fibers. The recording medium may be one or a combination of two or more of the above constituent materials. The recording medium may also be a three-dimensional shape such as a sheet, a sphere, or a rectangular parallelepiped. Examples of the recording medium include an absorptive recording medium having ink absorbency, a low absorptive recording medium having low ink absorbency, and a non-absorbent recording medium that does not absorb ink. Examples of the absorbent recording medium include a recording medium having an ink-absorbing ink-receiving layer on the surface thereof, a recording medium in which the substrate itself has ink-absorbing properties, etc. Examples of the absorbent recording medium include fabric, plain paper, and paper for inkjet printing. The low-absorbency recording medium may be, for example, coated paper provided with a coating layer having low ink absorbency. Non-absorbent recording media are made of non-ink-absorbent materials such as glass, metal, and plastic, and examples of such recording media include recording media that do not have an ink-absorbent ink-receiving layer on their surface, and recording media that have a non-ink-absorbent layer on their surface. EXAMPLES

[0101] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0102] [Ingredients for ink composition] The main materials of the ink compositions used in the following examples and comparative examples are as follows. [Pigments] Dispersion A Dispersion containing PR150 (azo pigment, Pigment Red 150) Dispersion B Dispersion containing PV19 (quinacridone pigment, Pigment Violet 19) Dispersion C Dispersion containing PR17 (azo pigment, Pigment Red 17) Dispersion D Dispersion containing PR122 (quinacridone pigment, Pigment Red 122) [Preparation of Pigment Dispersion] Pure water was added to 20% by mass of each pigment and 7% by mass of sodium hydroxide neutralized styrene-acrylic acid copolymer (acid value 175 mgKOH / g, molecular weight 10,000) to make the total 100% by mass, and the mixture was stirred and mixed to obtain a mixture. This mixture was placed in a wet sand mill filled with 0.3 mm diameter zirconia beads and dispersed for 6 hours. The zirconia beads were then removed using a separator, and the mixture was filtered through a cellulose acetate filter with a pore size of 3.0 μm to prepare a pigment dispersion. The styrene-acrylic acid copolymer is a water-soluble polymer that is generally used as a dispersant for pigments. The volume average particle diameter D50 measured by a particle size distribution meter was 100 nm for each.

[0103] [Lactam Compounds] HEP: 1-(2-hydroxyethyl)-2-pyrrolidone ε-Caprolactam [Penetrating agent] 1,2-Hexanediol [Organic Solvent] Gly: Glycerin TEG: Triethylene glycol

[0104] [Surfactant] Olfin E1010 (HLB: 13-14, acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) Olfin EXP4200 (HLB: 10-12, acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd.) Surfynol 104 (HLB: 4, manufactured by Air Products and Chemicals, Inc.) Surfynol SE-F (HLB: 6, manufactured by Air Products and Chemicals, Inc.)

[0105] 〔resin〕 Superflex 420 (polyurethane water dispersion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 〔alkali〕 TEA: Triethanolamine

[0106] [Preparation of Ink Composition] The pigment dispersion and each material were mixed in the composition shown in Figures 1 to 3 below and thoroughly stirred to obtain each ink composition. In Figures 1 to 3, the units of values ​​are mass %, and the total is 100.0 mass %. The pigment is the mass % of the pigment in the ink. All of the inks were red inks that could be used as magenta inks. Although not described below, they were inks that could be used as a set by separately preparing a yellow ink, a black ink, and a cyan ink. It was also possible to use the ink of the present embodiment as a red ink by further separately preparing a magenta ink and using this as a set. Each ink composition was evaluated as follows.

[0107] <Evaluation> (Visibility of the ink level in the tank) A modified inkjet recording device (Epson Corporation EW-M873T) was prepared. A CISS tank was installed, and the material of the inner wall of the liquid level indicator of the CISS tank was polypropylene. 150 mL of ink was poured into the main tank (CISS tank). After that, the ink in the main tank was removed, and 75 mL of ink was poured again. Three minutes after refilling the ink, the part of the liquid level indicator corresponding to the difference between 150 mL and 75 mL in the main tank was visually observed for ink adhesion, coloration, and ink amount (liquid level), and the visibility of the ink amount was evaluated according to the evaluation criteria shown below. "A" and "B" were considered acceptable levels, and "C" and "D" were considered unacceptable levels. [Evaluation Criteria] A: There was no ink adhesion or discoloration, and the liquid level on the liquid level indicator could be seen from a distance of 30 cm. B: A small amount of ink was present or the gas-liquid boundary was thin, but the remaining ink level could be confirmed on the liquid level indicator from a distance of 30 cm. C: There was little ink adhesion, but the liquid surface boundary was thin, making it difficult to visually confirm the liquid level on the liquid level indicator from a distance of 30 cm. D: There was a lot of ink adhesion, and it was difficult to visually confirm the liquid level on the liquid level indicator from a distance of 30 cm.

[0108] (defoaming time) 20 g of the ink composition was weighed and poured into a 100 g screw tube. The screw tube was shaken vertically 20 times, and the time until a bubble-free area with a diameter of 1 cm was formed when the liquid level was observed from above the screw tube was defined as the defoaming time, and was evaluated according to the following evaluation criteria. [Evaluation Criteria] A: Defoaming time <5 minutes B: 5 minutes ≦ defoaming time < 30 minutes C: 30 minutes≦defoaming time

[0109] (Initial filling property) The filtered and degassed ink composition was injected into the CISS tank of the inkjet recording device, which was an unused printer, and after waiting for bubbles that had formed during ink injection to subside, the inkjet head was initially filled with the ink. After the initial filling, a nozzle check printing was performed, and the presence or absence of print distortion or non-ejection was visually confirmed, and evaluated according to the evaluation criteria shown below. [Evaluation Criteria] A: There was no print distortion or non-ejection. B: Print distortion or non-ejection occurred. Printing deviation refers to the deviation of the ink landing position. A deviation in the landing position of ink droplets that is 50% or more of the distance between adjacent nozzles at a distance of 0.5 mm from the nozzle in the ejection direction is defined as printing deviation.

[0110] (Redispersibility) It was confirmed whether the ink composition that had once dried on the nozzle surface or the like would dissolve again when new ink composition was added. The ink composition was dropped onto a slide glass (2 μL×5 drops) and dried at 60° C. for one day. The dried ink composition was placed in water and left to stand for 3 minutes, then turned upside down 5 times. The slide glass was then removed and the ink remaining on the glass and re-solubility in water were evaluated according to the following criteria. [Evaluation Criteria] A: All the ink droplets were redissolved. B: The ink droplets were redissolved, but there was residual dried ink composition on the slide. C: The ink droplet did not redissolve and remained solid on the slide.

[0111] [Printing] The ink droplet mass is 12.5 ng / dot, the basic resolution is 600 x 600 dpi, and the ink deposition amount in a solid pattern is 5 mg / inch. 2 The dot density was adjusted (the number of ink droplets per pixel was adjusted) so that the image was printed on Xerox P paper (plain paper).

[0112] (Color development) A monochrome test pattern was recorded under the above printing conditions. The test pattern was measured with a colorimeter (Xrite i1 (manufactured by Xrite) to evaluate the OD value, and the color development was evaluated according to the following evaluation criteria. [Evaluation Criteria] A:OD value ≧0.85 B: 0.85>OD value≧0.75 C: 0.75>OD value

[0113] (Discharge stability) Printing was carried out continuously for 1 hour under the above printing conditions, and after printing, the print was visually checked for any distortion or omissions, and the ejection stability was evaluated according to the following evaluation criteria. A: There was no distortion or omission of print. B: Printing distortion or omissions occurred.

[0114] (Phase separation in ink state) The ink composition was placed in a glass screw tube and left for 24 hours in an environment at 60° C. After removing it from the environment at 60° C., it was visually confirmed whether the surfactant had separated and floated on the ink surface, and the phase separation in the ink state was evaluated according to the following evaluation criteria. A: There was no separation of the surfactant. B: The surfactant was separated or oily. C: The surfactant was completely separated and formed into two layers.

[0115] As shown in FIGS. 1 to 3, in the examples using the recording apparatus of this embodiment, the visibility of the ink amount and the initial filling were rated A or B, and the visibility and initial filling of the ink amount were excellent. On the other hand, Comparative Examples 1 and 6 to 9, which did not contain an azo pigment, were poor in visibility of the ink amount. Comparative Examples 2 and 3, which did not contain acetylene glycol surfactant B having an HLB value of 10 or more, were poor in visibility of the ink amount. Furthermore, Comparative Examples 4 and 5, which did not contain acetylene glycol surfactant A having an HLB value of less than 10, were poor in initial filling properties. [Explanation of symbols]

[0116] 1 Inkjet recording device 12 Paper feed slot 13 Support part 14 Paper output port 16 Carriage 17 Inkjet head 20 (20Bk, 20Cn, 20Ma, 20Yw) Subtank 24 Ink supply pipe (ink supply path) 50 Ink container 54(51) Ink inlet XX axis YY axis ZZ axis

Claims

1. A recording device having an ink container, an ink supply unit, an inkjet head, and an ink composition, the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates an ink liquid level of the ink composition contained in the ink container, the inkjet head receives the ink composition from the ink container via the ink supply unit, and ejects the ink composition onto a recording medium; The ink composition is a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more. Recording device.

2. the content of the acetylene glycol surfactant A is 0.1% by mass to 0.8% by mass with respect to the total amount of the ink composition; the content of the acetylene glycol surfactant B is 0.1% by mass to 0.8% by mass with respect to the total amount of the ink composition; The recording apparatus according to claim 1 .

3. The content of the azo pigment is 1.0% by mass to 8.0% by mass with respect to the total amount of the ink composition. The recording apparatus according to claim 1 .

4. The content of the lactam compound is 0.1% by mass to 7.0% by mass relative to the total amount of the ink composition. The recording apparatus according to claim 1 .

5. The red ink is a magenta ink. The recording apparatus according to claim 1 .

6. the ink composition contains 1,2-alkanediols having 4 to 8 carbon atoms, the content of the 1,2-alkanediol is 1.0% by mass to 4.0% by mass with respect to the total amount of the ink composition; The recording apparatus according to claim 1 .

7. Further comprising a cyan ink, a yellow ink, and a black ink, an inkjet head C that ejects the cyan ink, an inkjet head Y that ejects the yellow ink, and an inkjet head B that ejects the black ink, The recording apparatus according to claim 1 .

8. The azo pigment is at least one selected from the group consisting of C.I. Pigment Red 150, C.I. Pigment Red 269 and C.I. Pigment Red 17; The recording apparatus according to claim 1 .

9. A recording method using a recording apparatus having an ink container, an ink supply unit, and an inkjet head, comprising the steps of: a supplying step of supplying an ink composition from the ink container to the inkjet head via the ink supply unit; a deposition step of ejecting the ink composition from the inkjet head and depositing the ink composition on a recording medium, the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates an ink liquid level of the ink composition contained in the ink container, The ink composition is a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more. Recording method.

10. An ink composition for use in recording with a recording device having an ink container, an ink supply unit, and an inkjet head, comprising: the ink container has an ink inlet through which the ink composition is injected, and a liquid level indicator that indicates an ink liquid level of the ink composition contained in the ink container, the inkjet head receives the ink composition from the ink container via the ink supply unit, and ejects the ink composition onto a recording medium; a water-based red ink containing an azo pigment, an acetylene glycol surfactant A having an HLB value of less than 10, and an acetylene glycol surfactant B having an HLB value of 10 or more; Ink composition.

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