JP5089190B2 - Water-based ink, ink set, ink jet recording method, ink cartridge, recording unit and ink jet recording apparatus - Google Patents

Description

  The present invention relates to a technique for using a green pigment having a copper phthalocyanine skeleton as a coloring material for water-based ink. More specifically, the present invention relates to an aqueous ink (hereinafter referred to as ink), an ink set, an ink jet recording method using the ink, an ink cartridge, a recording unit, and an ink jet recording apparatus.

  It is well known to use an ink containing a pigment as a coloring material (pigment ink) in order to make an image obtained by the ink jet recording method excellent in light resistance, gas resistance and water resistance. However, pigments are generally inferior in color development compared to dyes. For this reason, in a color image formed using the three primary colors of cyan, magenta, and yellow, comparing the case where the dye ink is used with the case where the pigment ink is used, the image formed using the pigment ink is Obviously, the color reproduction range is narrowed. For this reason, there is a demand for the development of a technique capable of forming an image with excellent color balance and a wider color reproduction range by using pigment ink.

  On the other hand, when pigment ink is used, an image is formed using inks of intermediate colors such as red, green, and blue in addition to the three primary colors of cyan, magenta, and yellow. (See Patent Documents 1 to 3). In this case, the coloring material of the green ink for inkjet is generally C.I. which is a halogenated phthalocyanine pigment. I. Pigment Green 7 and C.I. I. Often Pigment Green 36 is used (for example, see Patent Document 4-7).

JP 2001-354886 A JP 2004-155826 A International Publication No. 2002/100959 Pamphlet JP 2000-355665 A JP 2004-339355 A JP 2002-332440 A JP 2003-012982 A

  The present inventors have proposed a green containing a green pigment having a copper phthalocyanine skeleton (hereinafter sometimes simply referred to as “green pigment”) as a coloring material for the purpose of expanding the color reproduction range of an image formed with pigment ink. The ink was mainly studied. In the course of the study, it was found that when the above-described green ink was ejected using an inkjet recording apparatus, ejection stability such as frequency responsiveness, stable ejection volume, and stable ejection speed may not be obtained. . This phenomenon is particularly remarkable in an ink jet recording apparatus that ejects ink from a recording head by the action of thermal energy. Furthermore, when the above-described ink is stored for a long period of time, the average particle size of pigment particles in the ink may increase or aggregates may precipitate.

  Accordingly, a first object of the present invention is to provide an ink having excellent ejection stability and storage stability despite the use of a green pigment having a copper phthalocyanine skeleton as a colorant for ink-jet ink. There is. The second object of the present invention is to provide an ink set that is excellent in color balance and can realize the formation of an image with a wider color reproduction range in an ink set that uses an ink that uses a green pigment having a copper phthalocyanine skeleton. It is to provide. Furthermore, another object of the present invention is to provide an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus using the ink or ink set.

The above object is achieved by the present invention described below. That is, the ink of the present invention is an ink-jet aqueous ink comprising at least a green pigment having a copper phthalocyanine skeleton and a water-soluble organic solvent, and the water-soluble organic solvent has at least a weight average molecular weight. The ratio of chlorine atom Kα ray intensity to bromine atom Kα ray intensity ( containing Kα ray intensity / bromine atom of chlorine atom) containing 1,000 or more polyethylene glycol and obtained by fluorescent X-ray analysis of the green pigment. (Kα ray intensity) of 3.3 or more and 10.0 or less.

  In addition, the ink set for inkjet according to another embodiment of the present invention is an ink set formed by combining a plurality of water-based inks, and the plurality of water-based inks include at least a green ink, a red ink, and a blue ink. The green ink is the water-based ink, and the color material of the red ink is C.I. I. Pigment red 149, and the color material of the blue ink is C.I. I. Pigment Violet 23.

  The ink jet recording method of the present invention is characterized in that the water-based ink or the ink jet ink set described above is used in an ink jet recording method in which ink is ejected by an ink jet recording method to perform recording on a recording medium.

  Further, the ink cartridge of the present invention is an ink cartridge having an ink storage portion for storing ink, wherein the ink stored is the water-based ink or the ink constituting the ink-jet ink set. And

  Further, the recording unit of the present invention is a recording unit including an ink storage portion that stores ink and a recording head that discharges ink, and the ink to be stored is the above-described water-based ink or the above ink-jet ink set. It is the ink which comprises.

  Further, the ink jet recording apparatus of the present invention is an ink jet recording apparatus having an ink containing portion for containing ink and a recording head for discharging the ink. It is the ink which comprises an ink set, It is characterized by the above-mentioned.

  According to the present invention, particularly when used in an ink jet recording system in which ink is continuously ejected from a recording head by the action of thermal energy, good ejection stability can be obtained, and when the ink is stored for a long period of time. A pigment ink having excellent storage stability is provided. According to another embodiment of the present invention, an ink set is provided that is excellent in color balance and can form an image in a wider color reproduction range. Furthermore, according to another embodiment of the present invention, it is possible to provide an ink jet recording method, an ink cartridge, a recording unit, and an ink jet recording apparatus that can stably obtain a high-quality image.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments. First, the background to the present invention will be described. In the course of studying a green ink containing a green pigment having a copper phthalocyanine skeleton, the present inventors have an influence on the ink ejection stability and storage stability due to the difference in substituents substituted on the skeleton of the pigment. I found out.

  Based on the above findings, the present inventors have made further detailed studies in order to make full use of the green pigment having a copper phthalocyanine skeleton as a coloring material for water-based ink. Green pigment having a copper phthalocyanine skeleton used in the aqueous ink of the present invention, C. I. Pigment green 7 and C.I. I. Pigment Green 36 is included. C. I. Pigment green 7 and C.I. I. Pigment Green 36 is a halogenated copper phthalocyanine pigment having both chlorine and bromine atoms as substituents. In addition, C.I. I. Pigment Green 36 is a C.I. I. Compared to Pigment Green 7, it is known that the proportion of bromine atoms is high. In the present invention, among the green pigments having a copper phthalocyanine skeleton, a halogenated copper phthalocyanine containing both a chlorine atom and a bromine atom as a substituent, particularly preferably a chlorine atom and a bromine atom are contained in a specific ratio. Use what you have.

  As a result of detailed studies by the present inventors, it has been found that the ratio of chlorine atoms and bromine atoms substituted for the halogenated copper phthalocyanine skeleton in the pigment has a great influence on the ejection stability and storage stability of the ink. . In particular, it has also been found that the influence on the ejection stability is conspicuous when ink is ejected using a so-called thermal ink jet recording apparatus that ejects ink from the recording head by the action of thermal energy.

  Therefore, the present inventors have found that the above-described green pigment configuration can be obtained, which is an ink containing a green pigment having a copper halide phthalocyanine skeleton, and can be an ink excellent in ejection stability and storage stability. The objective of 1 was examined. Specifically, as described below, several types of green pigments with different content ratios (substitution ratios) of chlorine atoms and bromine atoms substituted on the copper phthalocyanine skeleton were synthesized, and inks containing these pigments, The correlation with the characteristics was examined.

  First, in a eutectic salt of aluminum chloride and sodium chloride, copper phthalocyanine is dissolved and halogenated by introducing chlorine gas and bromine gas therein. The content ratio was changed. Furthermore, the ratio of chlorine atoms and bromine atoms bonded as substituents to the copper phthalocyanine skeleton of each pigment prepared as described above was determined using a fluorescent X-ray analyzer and the Kα-ray intensity of chlorine atoms and bromine atoms. This was done by measuring the Kα ray intensity of the atoms. Thereafter, a pigment dispersion was prepared using each of the pigments obtained above, and an ink material such as the pigment dispersion or an aqueous medium was mixed to prepare an ink. Each of the obtained inks was evaluated for ejection stability and storage stability, and the correlation between the content ratio of chlorine atoms and bromine atoms substituting for the copper phthalocyanine skeleton of the green pigment was examined.

  In the present invention, the ratio of the Kα ray intensity of chlorine atoms used to define the green pigment to the Kα ray intensity of bromine atoms (Kα ray intensity of chlorine atoms / Kα ray intensity of bromine atoms) is measured by the following method. did. That is, it can be calculated by using the peak intensity ratio of chlorine atoms and bromine atoms obtained by measurement under the conditions of an acceleration voltage of 40 KV and 1.20 mA using a fluorescent X-ray analyzer ZSXmin (manufactured by Rigaku Denki Kogyo). Of course, the present invention is not limited to this.

  Here, verification of whether or not the unknown ink contains the above-described green pigment can be performed by the following means. First, the ink is centrifuged, separating the solid and liquid components in the ink. Thereafter, only the precipitated solid component is collected and washed with ion exchange water. After the washed solid component is dried, it can be verified by measuring the Kα-ray intensity of chlorine atoms and the Kα-ray intensity of bromine atoms using an X-ray fluorescence analyzer and obtaining the ratio of these. .

  As a result of the above examination, it has been found that when a pigment having a ratio of the Kα-ray intensity of chlorine atoms to the Kα-ray intensity of bromine atoms smaller than 3.3 in the above-described green pigment is used, the ejection stability is lowered. . On the other hand, it was found that when a pigment larger than 10.0 is used, the storage stability is lowered. Therefore, in the present invention, a green pigment having a copper phthalocyanine skeleton is used in which the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms is within a specific range. That is, in the present invention, when a green pigment for obtaining the above effect is selected, the Kα-ray intensity of chlorine atoms and the Kα-ray intensity of bromine atoms obtained by fluorescent X-ray analysis of the pigment are measured, and the measured values are used. It prescribes | regulates so that the ratio of both calculated | required may become in the said specific range. As a result, a green pigment having a copper phthalocyanine skeleton that can function satisfactorily for the purpose of obtaining the effect can be defined.

  The reason why a large difference occurs in the ejection stability and storage stability of the ink by changing the content ratio (substitution ratio) of chlorine atom and bromine atom in the green pigment having a copper phthalocyanine skeleton is not clear. Guesses as follows.

[When the ratio of the Kα line intensity of chlorine atoms to the Kα line intensity of bromine atoms (= Kα line intensity of chlorine atoms / Kα line intensity of bromine atoms) is less than 3.3]
The green pigment used in the present invention is an aggregate of molecules in which a part of hydrogen atoms of the phthalocyanine skeleton are substituted with chlorine atoms and bromine atoms. Here, the atomic radius of bromine atoms is larger than the atomic radius of chlorine atoms. For this reason, it is considered that the higher the proportion of bromine atoms in the green pigment, the higher the bulk of the molecular aggregate. Ink jet ink is an aqueous ink containing an aqueous medium, and the pigment is insoluble in water. Therefore, the pigment as the coloring material is formed on the surface of the pigment particle with a resin (polymer dispersing agent), a surfactant, and further hydrophilic. A group or the like is present in the ink in an adsorbed or bonded state. As a result of the study by the present inventors, it has been found that as the molecules constituting the pigment are bulky, the resin, the surfactant, and further the hydrophilic group are difficult to adsorb or bind to the pigment surface. As a result of further detailed studies, the present inventors have determined that in the case of green pigments, resins and surfactants are pigments depending on the ratio of chlorine and bromine atom Kα-ray intensities measured by fluorescent X-ray analysis. It has been found that the range in which adsorption or binding to the surface is difficult can be quantified. More specifically, when a green pigment in which the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms is smaller than 3.3, a substance that enhances the hydrophilicity of the pigment surface such as a resin. It has been found that the amount of adsorbed or bound is reduced. In particular, it has also been found that when a resin is used as a substance for enhancing hydrophilicity, the higher the molecular weight of the resin or the higher the hydrophilicity, the more easily affected by steric hindrance and the resin is less likely to adsorb on the pigment surface.

  When an ink containing a pigment dispersion in which a substance that enhances hydrophilicity is not sufficiently adsorbed as described above is ejected using a thermal type ink jet recording apparatus, dispersion breakage occurs due to heat applied to the ink at the time of ejection. The frequency is thought to increase. The inventors presume that the reason why ejection failure occurs in an ink containing a green pigment in which the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms is less than 3.3 is as follows. Yes. That is, when such an ink is used for ink jet recording, it is considered that a large amount of dispersed debris is generated in the process of continuously discharging the ink because there is a shortage of substances that increase the hydrophilicity of the pigment surface. As a result, it is estimated that the frequency response, the discharge volume, and the discharge speed are reduced in the ink containing the green pigment having the above characteristics.

[When the ratio of the Kα ray intensity of the chlorine atom and the Kα ray intensity of the bromine atom (= Kα ray intensity of the chlorine atom / Kα ray intensity of the bromine atom) is greater than 10.0]
On the other hand, since the atomic radius of the chlorine atom is smaller than that of the bromine atom, it is considered that the smaller the bromine atom ratio, the smaller the steric hindrance. As a result, substances that enhance the hydrophilicity of the pigment surface, such as resins, surfactants, and even hydrophilic groups, tend to be adsorbed or bonded to the pigment surface, and should tend to improve dispersion stability. However, according to the study by the present inventors, if the ratio of bromine atoms becomes too small, more specifically, the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms becomes greater than 10.0. On the contrary, it was found that the dispersion stability tends to decrease. The present inventors presume this reason as follows. The pigment particles overlap each other to form one particle. At this time, if the proportion of bromine atoms having a large atomic radius is too small, the symmetry of the molecule is improved, and it is thought that this is because the crystallization of the molecules constituting the pigment particles is likely to proceed. . That is, the present inventors presume that the crystal growth becomes too difficult to disperse, and as a result, the dispersion stability decreases.

  Based on the above findings, the present inventors have found the following. That is, by using, as a color material, a green pigment in which the ratio between the Kα ray intensity of chlorine atoms and the Kα ray intensity of bromine atoms obtained by fluorescent X-ray analysis is 3.3 or more and 10.0 or less, ink discharge It was found that both stability and storage stability can be achieved. Here, FIG. 7 shows an example of the result of fluorescent X-ray analysis of a green pigment that can be used in the present invention. In FIG. 7, in this green pigment, the Kα ray intensity of chlorine atoms is 43.5 kcps, and the Kα ray intensity of bromine atoms is 11.2 kcps. Therefore, the ratio of the Kα line intensity of chlorine atoms to the Kα line intensity of bromine atoms (Kα line intensity of chlorine atoms / Kα line intensity of bromine atoms) is 3.9. In the ink of the present invention, the upper limit of the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms is more preferably 5.0 or less. Moreover, it is more preferable that the lower limit of the ratio of chlorine atoms to the Kα ray intensity of bromine atoms is not more than 4.0.

  In addition, as the coloring material of the ink for inkjet, the C.C. I. Pigment Green 7 and C.I. I. The use of pigment green 36 is well known. However, the C.I. I. Pigment Green 7 and C.I. I. Regarding the pigment green 36, when the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms was examined by the above method, the following was found. That is, the ratio of the Kα line intensity of chlorine atoms to the Kα line intensity of bromine atoms is the same for all investigated C.I. I. In Pigment Green 7, the value was greater than 10.0. Further, the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms is the same for all investigated C.I. I. In the pigment green 36, the value was smaller than 3.0. The reason for this is not clear, but is presumed as follows. Then, because it was with this arrangement, C. marketed for inkjet I. Pigment Green 7 and C.I. I. In the case of using Pigment Green 36, it is considered that the storage stability of the ink was not sufficient or the problem of ejection failure occurred.

  First, commercially available C.I. I. Since Pigment Green 7 contains a third substance called a crystal inhibitor, crystallization (pigment agglomeration) due to improved molecular symmetry as described above hardly occurs. Further, according to the study by the present inventors, as the proportion of chlorine atoms increases, it becomes less susceptible to steric hindrance. Therefore, the surface of the pigment such as a resin, a surfactant, or a hydrophilic group is not formed on the pigment surface. There is a tendency that a substance that enhances hydrophilicity is easily adsorbed. In view of the above, C.I. I. In Pigment Green 7, in order to obtain a stable pigment dispersion, a crystal inhibitor was included, and the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms was considered to be greater than 10.0. .

  In addition, C.I. I. Since Pigment Green 36 has a large number of bromine atoms substituted for the copper phthalocyanine skeleton, the molecular skeleton of the coloring material is considered to be large. For this purpose, conventional C.I. I. It is considered that the ink containing the pigment green 36 was a cause of insufficient ink storage stability. Furthermore, since it has the molecular structure as described above, commercially available C.I. I. It is considered that when ink containing Pigment Green 36 is applied to a thermal ink jet recording apparatus, ink ejection stability cannot be obtained sufficiently.

  According to the study by the present inventors, for the reasons described above, the conventional C.I. I. Pigment Green 7 and C.I. I. When the pigment green 36 is used, the following problems occur. In other words, it is considered that the crystal inhibitor may cause kogation or may be unfavorable in terms of ejection stability.

  Therefore, the present inventors have the following configuration as a configuration of an aqueous ink containing a green pigment having a copper phthalocyanine skeleton that can solve the problems of storage stability and ejection stability of the inkjet ink described above. I found it. That is, commercially available C.I. I. Pigment Green 7 and C.I. I. Using a green pigment having a copper phthalocyanine skeleton having a structure different from that of the pigment green 36. Specifically, a green pigment having a copper phthalocyanine skeleton “the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms is 3.3 or more and 10.0 or less” is used.

<Water-based ink>
The ink-jet aqueous ink that can achieve the first object of the present invention is as follows. That is, it comprises a green pigment having a copper phthalocyanine skeleton in which the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms obtained by fluorescent X-ray analysis is 3.3 or more and 10.0 or less. To do. However, the other ink configuration may be the same as that of the conventional water-based pigment ink for ink jet. Below, each component which comprises the water-based ink of this invention is demonstrated.

(Green pigment content)
The content of the green pigment as the color material in the aqueous ink of the present invention is 1.0% by mass or more and 10.0% by mass or less, further 2.0% by mass or more and 6% by mass or more based on the total mass of the aqueous ink. It is preferable that it is 0.0 mass% or less. If the content of the green pigment is less than 1.0% by mass, sufficient optical density may not be obtained, and if it exceeds 10.0% by mass, the sticking resistance may be lowered.

(Pigment dispersion method)
Any of the dispersion methods of the green pigment constituting the ink of the present invention can be used. Specifically, a resin dispersion type pigment (resin dispersion type pigment) that is dispersed using a dispersant can be used. It is also possible to use a microcapsule type pigment in which the surface of the pigment is coated with an organic polymer and encapsulated, or a self-dispersion type pigment (self-dispersion type pigment) in which a hydrophilic group is introduced on the surface of the pigment particle. it can. Furthermore, a pigment (polymer-bonded self-dispersing pigment) in which an organic group containing a polymer is chemically bonded to the surface of the pigment particle can also be used. Of course, these pigments having different dispersion methods can be used in combination. Hereinafter, these types of pigments will be described.

[Resin dispersion type pigment]
As the dispersant used for the resin-dispersed pigment, it is preferable to use a dispersant capable of stably dispersing the pigment in an aqueous medium by the action of a hydrophilic group, particularly an anionic group. As the dispersant, for example, the following can be used. Styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-maleic acid copolymer, styrene-maleic acid-alkyl acrylate copolymer. Styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer. Vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, styrene-maleic anhydride-maleic acid half ester copolymer, benzyl methacrylate-methacrylic acid copolymer, and the like. Or the salt of these copolymers.

  Moreover, it is preferable that the form of resin used as a dispersing agent is a block polymer. The reason is as follows. In the block polymer, hydrophilic units and hydrophobic units are regularly arranged in the molecular structure. On the other hand, in the random polymer, hydrophobic units and hydrophilic units are irregularly arranged in the molecular structure. For this reason, the block polymer has a hydrophobic unit that is easily adsorbed to the pigment locally to some extent in the resin structure as compared with the random polymer. Due to the difference in the form of the resin, the block polymer is less likely to be peeled off from the pigment than the random polymer, and it is easier to maintain high ejection stability. The block polymers that can be used in the present invention include the following. An AB block type in which a hydrophobic monomer unit (referred to as A block) and an ionic hydrophilic monomer unit (referred to as B block) are localized, or a nonionic hydrophilic monomer unit (referred to as C block), respectively. Examples include the added ABC block type. Of course, the present invention is not limited to this.

  The weight average molecular weight of the dispersing agent described above is preferably 1,000 to 30,000. In the present invention, the weight average molecular weight of the dispersant is particularly preferably 1,500 to 6,000, and more preferably 2,000 to 5,000. Here, the use of a resin having a weight average molecular weight of 1,500 or more and 6,000 or less as a dispersant is very rare in ordinary pigment inks for inkjet. However, in the present invention, it is particularly preferable to use a resin having such a low weight average molecular weight for the reasons described below. Since the green pigment used in the present invention adds a certain proportion of bulky atoms such as bromine atoms, it is considered difficult to adsorb substances such as resins that increase the hydrophilicity of the pigment surface. For this reason, in the case of the present invention, it is possible to use a resin having a weight average molecular weight of 1,500 to 6,000, and more preferably 2,000 to 5,000, which makes the ink ejection stability and long-term storage stability. It is more preferable to improve the property. The reason is not clear, the present inventors presume as follows.

  That is, in the case of a resin having a weight average molecular weight of 6,000 or less, and further 5,000 or less, since the weight average molecular weight is small, the adsorption amount of the resin due to steric hindrance peculiar to the green pigment used in the present invention is reduced. Difficult to be affected. As a result, even if the resin content in the ink is small, sufficient resin can be adsorbed on the pigment surface in order to disperse the green pigment in a stable state. Further, a resin having a weight average molecular weight of 1,500 or more, and further 2,000 or more can disperse the pigment in a sufficiently stable state. In addition, when the present inventors use a resin having a weight average molecular weight of 6,000 or less and further 5,000 or less as compared with a resin having a weight average molecular weight of 6,000 or more than 5,000, It was confirmed by the following method that the amount of adsorption of the resin to the green pigment surface is increased. That is, it confirmed by centrifuging the aqueous solution of the pigment dispersion which disperse | distributed the green pigment using resin from which a weight average molecular weight differs, and comparing the mass of the compound obtained by acidifying a supernatant liquid.

  Furthermore, a preferred resin when a green pigment having a ratio of chlorine atom and bromine atom as a substituent used in the present invention in a specific range is dispersed with a resin having a weight average molecular weight in the range of 1,500 to 6,000. The content of is as follows. That is, the content (mass%) of the resin in the ink is 0.5 times or more and 1.0 times or less based on the content (mass%) of the green pigment (resin content / green pigment content). It is preferable that

  If the content of the resin in the ink is 0.5 times or more based on the content of the pigment, even if the resin is peeled off from the pigment surface, the resin is again at the site where the resin is peeled off from the pigment surface. A sufficient resin is present in the ink to be adsorbed. As a result, even with a green pigment in which the resin is difficult to adsorb on the pigment surface due to the effect of steric hindrance, it is possible to adsorb enough resin to disperse the pigment in a stable state by configuring as described above. It is guessed. On the other hand, if the resin content in the ink is larger than 1.0 times based on the pigment content, the resin not adsorbed on the pigment increases in the case of the specific green pigment used in the present invention. To happen. For this reason, there is a case where the ejection stability is lowered due to an increase in the viscosity of the ink accompanying the evaporation of moisture in the ink in the vicinity of the ejection port of the recording head and the adhesion of the resin to the ejection port.

  The resin content (% by mass) in the ink is 0.5% by mass or more and 10.0% by mass or less, and further 0.5% by mass or more and 3.0% by mass or less, based on the total mass of the ink. Preferably there is. In particular, in the present invention, the resin content (% by mass) in the ink is particularly preferably 0.9% by mass or more and 1.8% by mass or less based on the total mass of the ink. When the resin content is 0.9% by mass or more and 1.8% by mass or less as described above, the discharge stability does not deteriorate, and excellent dispersion stability is obtained over a long period of time. Because it is.

[Self-dispersing pigment]
In the present invention, a self-dispersing pigment that can disperse a pigment in an aqueous medium without using a dispersant by binding an ionic group (for example, an anionic group) to the pigment surface can also be used. Examples of the self-dispersing pigment include an anionic pigment in which an anionic group as described below is bonded to the pigment surface.

Examples of the anionic self-dispersing pigment include those in which at least one anionic group such as —COOM, —SO ₃ M, —PO ₃ HM, and —PO ₃ M ₂ is bonded to the surface of the pigment. In the above formula, M represents a hydrogen atom, an alkali metal, ammonium, or organic ammonium.

[Microcapsule type pigment]
In the present invention, a microcapsule-type pigment obtained by coating a pigment with an organic polymer and microencapsulating it can also be used. Examples of the method for microencapsulating the pigment include a chemical production method, a physical production method, a physicochemical production method, and a mechanical production method. Specifically, interfacial polymerization method, in-situ polymerization method, submerged cured coating method, coacervation (phase separation) method, submerged drying method, melt dispersion cooling method, air suspension coating method, spray drying method , Acid precipitation method and phase inversion emulsification method.

[Polymer-bonded self-dispersing pigment]
In the present invention, a polymer-bonded self-dispersing pigment in which an organic group containing a polymer is chemically bonded to the surface of pigment particles can also be used. The polymer-bonded self-dispersing pigment contains a reaction product of a functional group chemically bonded to the surface of the green pigment directly or through another atomic group and a copolymer of an ionic monomer and a hydrophobic monomer. It is preferable to use it.

  Next, components other than the green pigment constituting the ink of the present invention will be described. As components other than the green pigment used in the present invention, any of those constituting conventional ink-jet inks can be used.

(Aqueous medium)
For the ink, it is preferable to use water or an aqueous medium containing water and a water-soluble organic solvent. The content (% by mass) of the water-soluble organic solvent in the ink is preferably 3.0% by mass or more and 50.0% by mass or less based on the total mass of the ink. The water content (% by mass) in the ink is preferably 50.0% by mass or more and 95.0% by mass or less based on the total mass of the ink.

  It is preferable to use deionized water as the water. Moreover, the following can be used for a water-soluble organic solvent, for example. Alkanols having 1 to 4 carbon atoms such as ethanol, isopropanol, n-butanol, isobutanol, secondary butanol and tertiary butanol. Carboxylic acid amides such as N, N-dimethylformamide or N, N-dimethylacetamide. Ketones or ketoalcohols such as acetone, methyl ethyl ketone, 2-methyl-2-hydroxypentan-4-one; Cyclic ethers such as tetrahydrofuran and dioxane. Glycerin. Glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2- or 1,3-propylene glycol, 1,2- or 1,4-butylene glycol, polyethylene glycol, and dithioglycol; 1,3-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, etc. Alcoholic alcohols. Alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether. Heterocycles such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylmorpholine. Sulfur-containing compounds such as dimethyl sulfoxide. These water-soluble organic solvents can be used alone or in combination of two or more.

  In the present invention, among the water-soluble organic solvents described above, it is particularly preferable to use glycerin, ethylene glycol, diethylene glycol, polyethylene glycol, or 2-pyrrolidone. Further, when the above-mentioned resin having a weight average molecular weight of 1,500 to 6,000, more preferably 2,000 to 5,000 is used as the dispersant for the green pigment, the average molecular weight is 1, It is particularly preferred to use 000 or more polyethylene glycol. This is because the ink containing the above-described resin having a weight average molecular weight and polyethylene glycol having an average molecular weight of 1,000 or more has particularly good ejection stability when ejected continuously for a long period of time. In addition, it is preferable that the upper limit of the average molecular weight of polyethylene glycol is 1,500 or less. Further, when the ink contains polyethylene glycol, particularly excellent discharge stability can be obtained when the polyethylene glycol content is equal to or greater than the content of the green pigment in the ink.

(Other additives)
In addition to the components described above, the ink of the present invention may further contain various additives as necessary. For example, solid humectants such as urea and urea derivatives, trimethylolethane, and trimethylolpropane can be used. Furthermore, in order to obtain an ink having desired physical properties, a surfactant such as an acetylene glycol derivative, an antifoaming agent, a preservative, and an antifungal agent can be used.

<Ink set>
Next, an ink set having excellent color balance and capable of forming an image with a wider color reproduction range will be described. The second object of the present invention is to make the color reproduction range in an image formed with a plurality of pigment inks including an ink containing a green pigment as excellent as an image formed with a dye ink. Various studies were conducted.

  As a result, in order to widen the color reproduction range in an image formed with pigment ink, it is sufficient to simply use ink containing a highly saturated color material in addition to the three primary color inks of cyan, magenta, and yellow. It was found that the effect is not obtained. In addition, in order to widen the color reproduction range of an image, in particular, the color materials used for these inks are selected in consideration of the mutual influence of the light absorption characteristics of the color materials used for the red, green, and blue inks. I also found it important. The inventors of the present invention have an excellent color balance and a wider color range by using an ink set that combines red, green, and blue inks each containing a color material selected in consideration of these matters. It was found that image formation in the reproduction range can be realized.

Therefore, the inventors decided to study the fourth, fifth, and sixth color inks that are used in addition to the three primary colors of cyan, magenta, and yellow. Specifically, after preparing dozens of types of pigment dispersions having almost the same particle size distribution and dispersant as the pigment, an ink material such as an aqueous medium usually used for ink-jet inks is mixed to obtain several tens of pigment dispersions. A variety of water-based inks were prepared. Next, each of the inks obtained above was applied to several types of recording media by an ink jet recording method to form an image. About the obtained image, the a ^* value and b ^* value in the L ^* a ^* b ^* color system specified by CIE (International Commission on Illumination) were measured, and the saturation was calculated from these values. Further, on the basis of the measurement result of the saturation, three types of inks having the highest saturation were selected in the blue region, the red region, and the green region. Then, an image including a multi-order color (secondary color, tertiary color, etc.) region was formed using the three types of inks, and the color balance and the color reproduction range were evaluated. By combining the three types of inks that give the highest saturation selected in this way, a level equivalent to the color balance and color reproduction range obtained by the conventional pigment ink set is reached. However, the level higher than that, of course, did not reach the same level as the dye ink.

  Therefore, the present inventors arbitrarily combined the tens of types of inks obtained above to form an image including a multi-color (secondary color, tertiary color, etc.) region, and the obtained image In the same manner as described above, the color balance and the color reproduction range were evaluated. As a result, it was found that the image formed by combining the inks constituting the ink set of the present invention described below has the best color balance and color reproduction range in the blue region, red region, and green region. It was. This means that even when a multi-order image is formed using a combination of a plurality of inks containing a coloring material that gives the highest saturation in each hue, the best color balance and color reproduction range are the widest. It means not.

  Based on the results of the above studies, the present inventors have found each pigment ink that constitutes the ink set of the present invention that is excellent in color balance and that can form an image with a wider color reproduction range. .

First, as green ink and blue ink used when forming images in the third and fourth quadrants represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by the CIE, It is preferable to use an ink containing the following coloring material. That is, the color material of the green ink is C.I. I. Pigment Green 7 and the blue ink color material is C.I. I. Pigment Violet 23 is preferable. By using a combination of such green ink and blue ink, the color reproduction ranges of the third and fourth quadrants represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by the CIE can be obtained. It can be particularly widened.

The color material of red ink used when forming images in the first quadrant and the second quadrant represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by the CIE is C . I. Pigment Red 149 is preferable. By using such a red ink, the color reproduction range of the first quadrant and the second quadrant represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by CIE can be particularly widened. .

In addition, as red ink and blue ink used when forming images in the first quadrant and the fourth quadrant represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by the CIE, It is preferable to use an ink containing the following coloring material. That is, the color material of red ink is C.I. I. Pigment Red 149, and the blue ink coloring material is C.I. I. Pigment Violet 23 is preferable. By using such red ink and blue ink in combination, the color reproduction ranges of the first quadrant and the fourth quadrant represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by the CIE can be obtained. It can be particularly widened.

As a result of the above examination, the optimum combination of green ink, blue ink, and red ink constituting the ink set is determined as an ink containing the following specific color materials. That is, the color material used in the ink set of the present invention is the same as that of the green ink. I. Pigment Green 7 and blue ink color material C.I. I. Pigment Violet 23, and the red ink coloring material is C.I. I. Pigment Red 149. By using a combination of such green ink, blue ink, and red ink as a set, the first quadrant represented by the a ^* b ^* coordinates in the L ^* a ^* b ^* color system defined by the CIE is used. In particular, the color reproduction range of the quadrant area can be expanded. Furthermore, an image excellent in color balance can be obtained by using such an ink set.

  An image formed with a plurality of inks each containing the above specific color material has a better color balance than an image formed with a plurality of inks each containing a color material that gives the highest saturation in each hue. , reason why becomes a wider color reproduction range is clearly not clear. The present inventors speculate about this reason as follows.

  When an image including a multi-color (secondary color, tertiary color, etc.) region is formed using each of the inks constituting the ink set of the present invention, a plurality of color materials are formed in the image region on the recording medium. It exists in a mixed state. At this time, it is considered that the light absorption characteristics unique to each color material have some influence on each other's light absorption characteristics. It is unclear at present what kind of influence each color material contained in each ink constituting the ink set of the present invention has on the recording medium. However, from the facts described above, it is considered that the combination of the respective inks constituting the ink set of the present invention produces a certain synergistic effect that mutually improves the light absorption characteristics inherent to the respective color materials. As a result, it is estimated that a wider color reproduction range than the performance specific to each color material can be obtained.

  The ink set of the present invention in which the blue, red, and green inks containing the specific color materials described above are combined may be used in combination with other inks. For example, in addition to the respective inks constituting the ink set of the present invention, three primary colors of cyan, magenta, and yellow, and further black ink can be used. Also in this case, when using an ink set composed of each of the blue, red, and green inks of the present invention in comparison with a combination of a plurality of inks containing a coloring material that gives the highest saturation in each hue. The color balance and the color reproduction range are better. The effects described above can be obtained particularly remarkably when the following inks are used as the three primary color inks. That is, C.I. I. Yellow ink containing CI Pigment Yellow 74, C.I. I. Magenta ink containing CI Pigment Red 122, and C.I. I. It is particularly preferable to use three primary colors of cyan ink containing CI Pigment Blue 15: 3. Of course, the ink that can be used in addition to the ink set of the present invention is not limited to the above.

  Each ink constituting the ink set of the present invention can obtain a remarkable effect when used in an ink jet recording method using thermal energy. This is because each ink constituting the ink set of the present invention has good ejection stability, so that a wider color reproduction range can be obtained even when the ejection amount is small.

  Next, the structures characterizing the green ink, the blue ink, and the red ink constituting the ink set of the present invention will be specifically described.

(Green ink)
As described above, the green ink constituting the ink set of the present invention is a C.I. I. Pigment Green 7 is contained. C. in green ink I. The content (% by mass) of Pigment Green 7 is 1.0% by mass or more and 10.0% by mass or less, and further 2.0% by mass or more and 6.0% by mass or less based on the total mass of the ink. preferable.

  Here, as the green ink constituting the ink set of the present invention, it is particularly preferable to use an ink containing a green pigment with a specified substituent among the aqueous inks of the present invention described above. Specifically, in the green ink, the ratio of the Kα ray intensity of chlorine atoms to the Kα ray intensity of bromine atoms obtained by fluorescent X-ray analysis of the contained green pigment is 3.3 or more and 10.0 or less. It is preferable that. Further, the green ink particularly preferably contains a resin having a weight average molecular weight in the range of 2,000 to 5,000 as the resin for dispersing the green pigment.

(Blue ink)
The blue ink constituting the ink set of the present invention is C.I. I. Pigment Violet 23 is contained. C. in blue ink I. The content (mass%) of Pigment Violet 23 is 0.1 mass% or more and 15.0 mass% or less, more preferably 1.0 mass% or more and 10.0 mass% or less, particularly 1 based on the total mass of the ink. It is preferable that it is 0.0 mass% or more and 3.0 mass% or less.

As the blue ink constituting the ink set of the present invention, an ink having the following light absorption characteristics is preferably used. That is, it is preferable that the absorption wavelength at the maximum absorption wavelength satisfies the following relationship, respectively, having a maximum absorption wavelength in a wavelength range of 530 nm to 540 nm and a wavelength range of 550 nm to 570 nm. The relationship between the absorbance (A) at the maximum absorption wavelength in the range of 530 nm to 540 nm and the absorbance (B) at the maximum absorption wavelength in the range of 550 nm to 570 nm satisfies the following formula (1). It is preferable. When the blue ink satisfies the condition of the following formula (1), the color developability in the image formed with the blue ink can be made particularly excellent.

(Red ink)
The red ink constituting the ink set of the present invention is C.I. I. Pigment Red 149 is contained. C. in the red ink I. The content (% by mass) of Pigment Red 149 is 1.0% by mass or more and 10.0% by mass or less, and further 3.0% by mass or more and 5.0% by mass or less, based on the total mass of the ink. preferable.

C. I. When magenta ink containing Pigment Red 122 is combined with each ink constituting the ink set of the present invention to form an image, the magenta ink and the red ink constituting the ink set preferably satisfy the following conditions: . That is, the absorbance of the diluted ink obtained by diluting the magenta ink and the red ink with water to the same magnification is measured. The absorbance at each wavelength is summed from the obtained absorption spectrum of each diluted ink. This is defined as an absorption spectrum obtained by adding up the absorbance. At this time, in the absorption spectrum obtained by adding up the absorbance, it is preferable that the relationship between the maximum absorbance (C) and the minimum absorbance (D) in the range of 450 nm to 570 nm satisfies the condition of the following formula (2). When magenta ink and red ink satisfy the condition of the following formula (2), the color reproduction range of the red region, that is, the a ^* b ^* coordinate in the L ^* a ^* b ^* color system defined by the CIE is expressed. The color reproduction range of the first quadrant can be expanded particularly effectively.

(Pigment dispersion method)
The blue ink, red ink, and green ink constituting the ink set of the present invention may be inks in which pigments used for each ink are dispersed in water or an aqueous medium containing water and a water-soluble organic solvent. preferable. The method for dispersing these pigments in an aqueous medium is not particularly limited, and a dispersion method similar to that of the aqueous ink (aqueous ink containing a green pigment) of the present invention described above can be used. At this time, as the dispersant for dispersing the pigment, the same resin as that used in the above-described aqueous ink of the present invention can be used.

(Aqueous medium and other additives)
The aqueous medium and other additives used for the blue ink, red ink, and green ink constituting the ink set of the present invention are the same as the aqueous medium and other additives used for the aqueous ink of the present invention as described above. Can be used. In this case, the content of the aqueous medium and other additives can be the same as that of the aqueous ink of the present invention.

<Inkjet recording method>
The inks and inks constituting the ink set of the present invention are particularly preferably used in an ink jet recording method in which ink is ejected by an ink jet recording method and recording is performed on a recording medium. Ink jet recording methods include a method of ejecting ink by applying mechanical energy to the ink, a method of ejecting ink by applying thermal energy to the ink, and the like. In particular, each ink constituting the ink or ink set of the present invention can obtain a remarkable effect when used in an ink jet recording method using thermal energy.

<Ink cartridge>
The ink cartridge of the present invention is characterized by including an ink storage portion that stores each ink constituting the ink or ink set of the present invention.

<Recording unit>
The recording unit of the present invention includes an ink storage unit that stores each ink constituting the ink or ink set of the present invention, and a recording head that discharges the ink. In particular, when the recording head is a recording unit that ejects ink by applying thermal energy to the ink, a remarkable effect can be obtained.

<Inkjet recording apparatus>
An ink jet recording apparatus according to the present invention includes an ink storage unit that stores each ink constituting the ink or ink set of the present invention, and a recording head that discharges the ink. In particular, when the recording head is an ink jet recording apparatus that ejects ink by applying thermal energy to the ink, a remarkable effect can be obtained.

  Below, the schematic structure of the mechanism part of an inkjet recording device is demonstrated. The ink jet recording apparatus includes a paper feeding unit, a transport unit, a carriage unit, a paper discharging unit, a cleaning unit, and an exterior unit that protects these parts and provides design properties from the role of each mechanism. Hereinafter, an outline of these will be described.

  FIG. 1 is a perspective view of the ink jet recording apparatus. 2 and 3 are diagrams for explaining the internal mechanism of the ink jet recording apparatus. FIG. 2 is a perspective view from the upper right portion, and FIG. 3 is a side sectional view of the ink jet recording apparatus. is there.

  When performing paper feeding, first, a predetermined number of recording media are sent to a nip portion including a paper feeding roller M2080 and a separation roller M2041 in a paper feeding unit including a paper feeding tray M2060 (FIGS. 1 and 3). reference). The recording medium is separated at the nip portion, and only the uppermost recording medium is conveyed. The recording medium sent to the conveyance unit is guided by the pinch roller holder M3000 and the paper guide flapper M3030, and is sent to the roller pair of the conveyance roller M3060 and the pinch roller M3070. A pair of rollers including a conveyance roller M3060 and a pinch roller M3070 is rotated by driving of the LF motor E0002, and the recording medium is conveyed on the platen M3040 by this rotation (see FIGS. 2 and 3 above).

  When forming an image, the carriage unit places the recording head H1001 (see FIG. 4) at a target image forming position, and ink is ejected onto the recording medium in accordance with a signal from the electric substrate E0014 (see FIG. 2). The The detailed configuration of the recording head H1001 will be described later. The main scanning in which the carriage M4000 (see FIG. 2) scans in the column direction while recording is performed by the recording head H1001, and the sub-scan in which the transport roller M3060 (see FIGS. 2 and 3) transports the recording medium in the row direction alternately. By repeating the above, an image is formed on the recording medium.

  Finally, the recording medium is sandwiched by the nip between the first paper discharge roller M3110 and the spur M3120 at the paper discharge unit (see FIG. 3), conveyed, and discharged to the paper discharge tray M3160 (see FIG. 1).

  The cleaning unit cleans the recording head H1001. When the pump M5000 (see FIG. 2) is operated in a state where the cap M5010 (see FIG. 2) is in close contact with the ejection port of the recording head H1001, the cleaning unit sucks ink or the like from the recording head H1001. Further, if the ink remaining in the cap M5010 is sucked with the cap M5010 opened, ink sticking and other harmful effects do not occur.

(Configuration of recording head)
The configuration of the head cartridge H1000 will be described (see FIG. 4). The head cartridge H1000 has a recording head H1001, means for mounting the ink cartridge H1900, and means for supplying ink from the ink cartridge H1900 to the recording head. The head cartridge H1000 is detachably mounted on the carriage M4000 (see FIG. 2).

  FIG. 4 is a diagram showing how the ink cartridge H1900 is mounted on the head cartridge H1000. The ink jet recording apparatus forms an image with, for example, yellow, magenta, cyan, black, red, green, and blue inks. Therefore, the ink cartridge H1900 is also prepared for seven colors independently. In the above, at least one of the ink, using the respective inks constituting the ink or ink set of the present invention. As shown in FIG. 4, each ink cartridge is detachable from the head cartridge H1000. The ink cartridge H1900 can be attached and detached while the head cartridge H1000 is mounted on the carriage M4000 (see FIG. 2).

  FIG. 5 is an exploded perspective view of the head cartridge H1000. The head cartridge H1000 includes a recording element substrate, a plate, an electric wiring substrate H1300, a tank holder H1500, a flow path forming member H1600, a filter H1700, a seal rubber H1800, and the like. The recording element substrate is composed of a first recording element substrate H1100 and a second recording element substrate H1101, and the plate is composed of a first plate H1200 and a second plate H1400.

  The first recording element substrate H1100 and the second recording element substrate H1101 are Si substrates, and a plurality of recording elements (nozzles) for ejecting ink are formed on one side thereof by a photolithography technique. An electric wiring such as Al for supplying electric power to each recording element is formed by a film forming technique, and a plurality of ink flow paths corresponding to individual recording elements are also formed by a photolithography technique. Further, an ink supply port for supplying ink to the plurality of ink flow paths is formed to open on the back surface.

  FIG. 6 is an enlarged front view illustrating the configuration of the first recording element substrate H1100 and the second recording element substrate H1101. H2000 to H2600 are printing element rows (hereinafter also referred to as nozzle rows) for supplying different inks. On the first recording element substrate H1100, nozzle rows for three colors, a nozzle row H2000 for yellow ink, a nozzle row H2100 for magenta ink, and a nozzle row H2200 for cyan ink, are formed. On the second recording element substrate H1101, nozzle rows for four colors, a red ink nozzle row H2300, a black ink nozzle row H2400, a green ink nozzle row H2500, and a blue ink nozzle row H2600, are formed. Yes.

Each nozzle row is composed of 768 nozzles arranged at an interval of 1,200 dpi (dot / inch; reference value) in the conveyance direction of the recording medium, and ejects about 2 picoliters of ink. The opening area at each discharge port is set to about 100 μm ² .

  Hereinafter, a description will be given with reference to FIGS. The first recording element substrate H1100 and the second recording element substrate H1101 are bonded and fixed to the first plate H1200. Here, an ink supply port H1201 for supplying ink to the first recording element substrate H1100 and the second recording element substrate H1101 is formed. Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200. The second plate H1400 holds the electrical wiring substrate H1300 so that the electrical wiring substrate H1300 is electrically connected to the first recording element substrate H1100 and the second recording element substrate H1101.

  The electrical wiring substrate H1300 applies an electrical signal for ejecting ink from each nozzle formed on the first recording element substrate H1100 and the second recording element substrate H1101. The electric wiring board H1300 is arranged on the electric wiring corresponding to the first recording element substrate H1100 and the second recording element substrate H1101, and an external part for receiving an electric signal from the ink jet recording apparatus. And a signal input terminal H1301. The external signal input terminal H1301 is positioned and fixed on the back side of the tank holder H1500.

  In the tank holder H1500 that holds the ink cartridge H1900, a flow path forming member H1600 is fixed by, for example, ultrasonic welding to form an ink flow path H1501 that communicates from the ink cartridge H1900 to the first plate H1200. A filter H1700 is provided at the ink cartridge side end of the ink flow path H1501 that engages with the ink cartridge H1900, and can prevent dust from entering from the outside. Further, a seal rubber H1800 is attached to the engaging portion with the ink cartridge H1900 so that the ink can be prevented from evaporating from the engaging portion.

  Furthermore, as described above, the head cartridge H1000 is configured by bonding the tank holder portion and the recording head portion H1001 by bonding or the like. The tank holder portion includes a tank holder H1500, a flow path forming member H1600, a filter H1700, and a seal rubber H1800. The recording head portion H1001 includes a first recording element substrate H1100, a second recording element substrate H1101, a first plate H1200, an electric wiring substrate H1300, and a second plate H1400.

  Here, as an embodiment of the recording head, a thermal ink jet recording head that performs recording using an electrothermal transducer (recording element) that generates thermal energy for causing ink to cause film boiling in accordance with an electrical signal. Said. About this typical structure and principle, for example, what is performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 is preferable. . This method can be applied to both a so-called on-demand type and a continuous type.

  Thermal ink jet system is particularly effective to apply to on-demand type. In the case of the on-demand type, at least one drive that applies a rapid temperature rise exceeding nucleate boiling corresponding to the recording information to the electrothermal transducer disposed corresponding to the liquid flow path holding the ink Apply a signal. As a result, thermal energy is generated in the electrothermal transducer, and film boiling occurs in the ink. As a result, bubbles in the ink corresponding to the drive signal on a one-to-one basis can be formed. At least one droplet is formed by ejecting ink through the ejection port by the growth and contraction of the bubbles. It is more preferable that the driving signal has a pulse shape, since the bubble grows and contracts immediately and appropriately, so that ink discharge with particularly excellent response can be achieved.

  In addition, each ink constituting the ink or ink set of the present invention is not limited to the thermal ink jet method described above, and can be preferably used in an ink jet recording apparatus using mechanical energy as described below. An ink jet recording apparatus having such a configuration includes a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed to face the nozzles, and ink filling the periphery of the pressure generating element. Become. Then, the pressure generating element is displaced by the applied voltage, and ink is ejected from the nozzle.

  As described above, the ink jet recording apparatus is not limited to one in which the recording head and the ink cartridge are separated from each other. Further, the ink cartridge is integrated with the recording head so as to be separable or non-separable and mounted on the carriage, and is provided at a fixed portion of the ink jet recording apparatus, and recording is performed via an ink supply member such as a tube. An ink may be supplied to the head. Further, when the ink cartridge is provided with a configuration for applying a preferable negative pressure to the recording head, the following configuration can be adopted. That is, a mode in which an absorber is disposed in the ink storage portion of the ink cartridge, or a mode in which a flexible ink storage bag and a spring portion that applies a biasing force in the direction of expanding the inner volume of the flexible ink storage bag are provided. It can be. The ink jet recording apparatus may take the form of a line printer in which recording elements are aligned over a range corresponding to the entire width of the recording medium, in addition to the serial type recording method described above.

Hereinafter, the present invention will be described more specifically with reference to Examples , Reference Examples and Comparative Examples. The present invention is not limited to these unless it exceeds the gist. In the following description, “parts” and “%” are based on mass unless otherwise specified.

<Preparation of green pigment>
(Preparation of green pigment A)
In a reactor having a stirrer and a halogen gas introduction tube, 180 g of aluminum chloride and 42 g of sodium chloride were heated at 160 ° C. for 5 hours with mixing. Thereafter, after further stirring for 2 hours, the temperature was raised to 100 ° C., and 60 g of copper phthalocyanine was added. Furthermore, chlorine gas and bromine gas in a ratio of 10: 1 were introduced into the reactor at a flow rate of 9 g / h to perform halogenation of copper phthalocyanine. The obtained substance was discharged into water, washed and dried to obtain 80 g of green pigment A. The obtained green pigment A is subjected to fluorescent X-ray analysis to calculate the Kα ray intensity of chlorine atoms and the Kα ray intensity of bromine atoms, and the ratio thereof (Kα ray intensity of chlorine atoms / Kα ray intensity of bromine atoms). ) The results are shown in Table 1.

(Preparation of green pigments B, C, D, and E)
Green pigments B, C, D, and different content ratios of chlorine atoms and bromine atoms in the same manner as green pigment A, except that the ratio of chlorine gas and bromine gas in the preparation of green pigment A is changed. E was prepared. In addition, the content ratio of the chlorine atom and the bromine atom in the green pigment was changed by appropriately changing the mixing ratio of the chlorine gas and the bromine gas used when halogenating copper phthalocyanine. Here, in general, in the mixed gas of chlorine gas and bromine gas, the content ratio of bromine atoms substituted for the copper phthalocyanine skeleton increases by increasing the bromine gas content. Then, X-ray fluorescence analysis of the obtained green pigments B, C, D, and E is performed to calculate the Kα ray intensity of the chlorine atom and the Kα ray intensity of the bromine atom, and the ratio thereof (the chlorine atom concentration). Kα ray intensity / bromine atom Kα ray intensity) was determined. The results are shown in Table 1.

<Preparation of green pigment dispersion>
Using each green pigment obtained above, each green pigment dispersion was prepared by the following procedure and composition.

(Preparation of Green Pigment Dispersion 1)
A pigment solution was prepared by mixing 15 parts of the green pigment A, 7.5 parts of a dispersant, and 77.5 parts of ion-exchanged water. The dispersant was obtained by neutralizing an AB block polymer having an acid value of 250 and a weight average molecular weight of 6,000, synthesized by a conventional method using benzyl methacrylate and methacrylic acid as raw materials, with an aqueous potassium hydroxide solution. Resin A was used. This pigment solution was charged into a batch type vertical sand mill (manufactured by IMEX), filled with 85 parts of 0.3 mm zirconia beads, and dispersed for 3 hours while cooling with water. Thereafter, the non-dispersed material containing coarse particles was removed by centrifugation. Furthermore, the green pigment dispersion 1 having a pigment content (solid content) of 10% by mass and a resin content of 5% by mass by pressure filtration with a micro filter (manufactured by Fuji Film) having a pore size of 3.0 μm. Was prepared.

(Preparation of Green Pigment Dispersion 2)
Green pigment dispersion 2 was prepared in the same manner as green pigment dispersion 1, except that green pigment B was used instead of green pigment A. The obtained green pigment dispersion 2 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of Green Pigment Dispersion 3)
A green pigment dispersion 3 was prepared in the same manner as the green pigment dispersion 1 except that the resin A as the dispersant was changed. The dispersant was obtained by neutralizing an AB type block polymer having an acid value of 250 and a weight average molecular weight of 5,000, synthesized by a conventional method using benzyl methacrylate and methacrylic acid as raw materials, with an aqueous potassium hydroxide solution. Resin B was used. The obtained green pigment dispersion 3 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 4)
A green pigment dispersion 4 was prepared in the same manner as the green pigment dispersion 1 except that the resin A as the dispersant was changed. The dispersant was obtained by neutralizing an AB type block polymer having an acid value of 250 and a weight average molecular weight of 2,000, synthesized by a conventional method using benzyl methacrylate and methacrylic acid as raw materials, with an aqueous potassium hydroxide solution. Resin C was used. The obtained green pigment dispersion 4 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 5)
Green pigment dispersion 5 was prepared in the same manner as green pigment dispersion 1, except that 15 parts of green pigment B, 6 parts of resin B, and 79 parts of ion-exchanged water were used. The obtained green pigment dispersion 5 had a pigment content (solid content) of 10% by mass and a resin content of 4% by mass.

(Preparation of green pigment dispersion 6)
A green pigment dispersion 6 was prepared in the same manner as the green pigment dispersion 1 except that the green pigment A was 15 parts, the resin B was 16.5 parts, and ion-exchanged water was 68.5 parts. . The obtained green pigment dispersion 6 had a pigment content (solid content) of 10% by mass and a resin content of 11% by mass.

(Preparation of green pigment dispersion 7)
A green pigment dispersion 7 was prepared in the same manner as the green pigment dispersion 1, except that 15 parts of the green pigment C, 7.5 parts of the resin A, and 77.5 parts of ion-exchanged water were used. . The obtained green pigment dispersion 7 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 8)
A green pigment dispersion 8 was prepared in the same manner as the green pigment dispersion 1 except that the resin A as the dispersant was changed. The dispersant was obtained by neutralizing an AB type block polymer having an acid value of 250 and a weight average molecular weight of 1,500, which was synthesized by a conventional method using benzyl methacrylate and methacrylic acid as raw materials, with an aqueous potassium hydroxide solution. Resin D was used. The obtained green pigment dispersion 8 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 9)
A green pigment dispersion 9 was prepared in the same manner as the green pigment dispersion 1 except that the resin A as the dispersant was changed. The dispersant is a resin E obtained by neutralizing a random polymer having an acid value of 250 and a weight average molecular weight of 5,000, synthesized by a conventional method using benzyl methacrylate and methacrylic acid as raw materials, with an aqueous potassium hydroxide solution. Was used. The obtained green pigment dispersion 9 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 10)
A green pigment dispersion 10 was prepared in the same manner as the green pigment dispersion 1 except that 15 parts of the green pigment A, 3 parts of the resin B, and 87 parts of ion-exchanged water were used. The obtained green pigment dispersion 10 had a pigment content (solid content) of 10% by mass and a resin content of 2% by mass.

(Preparation of green pigment dispersion 11)
A green pigment dispersion 11 was prepared in the same manner as the green pigment dispersion 1 except that 15 parts of the green pigment D, 7.5 parts of the resin A, and 77.5 parts of ion-exchanged water were used. . The obtained green pigment dispersion 11 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 12)
A green pigment dispersion 12 was prepared in the same manner as the green pigment dispersion 1 except that 15 parts of the green pigment E, 7.5 parts of the resin A, and 77.5 parts of ion-exchanged water were used. . The obtained green pigment dispersion 12 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass.

(Preparation of green pigment dispersion 13)
A pigment solution was prepared by mixing 10 parts of the green pigment A, 9 parts of the resin B, and 81 parts of ion-exchanged water. This pigment solution was charged into a circulating bead mill, filled with 85 parts of 0.3 mm zirconia beads, and dispersed for 3 hours at a peripheral speed of 4 m / sec while cooling with water. Thereafter, the non-dispersed material containing coarse particles was removed by centrifugation. Furthermore, the green pigment dispersion 13 having a pigment content (solid content) of 10% by mass and a resin content of 9% by mass by pressure filtration with a micro filter (manufactured by Fuji Film) having a pore size of 3.0 μm. Was prepared.

(Preparation of green pigment dispersion 14)
Instead of green pigment A, C.I. I. Green Pigment Dispersion 14 was prepared in the same manner as Green Pigment Dispersion 3, except that Pigment Green 36 (product name: Lionol Green 6YK; manufactured by Toyo Ink) was used and the dispersion time was 5 hours. The obtained green pigment dispersion 14 had a pigment content (solid content) of 10% by mass and a resin content of 5% by mass. The C.I. I. X-ray fluorescence analysis of Pigment Green 36 is performed to calculate the Kα ray intensity of the chlorine atom and the Kα ray intensity of the bromine atom, and obtain the ratio (Kα ray intensity of the chlorine atom / Kα ray intensity of the bromine atom). As a result, it was 0.06.

<Preparation of pigment dispersion of each color>
Using each commercially available pigment, a pigment dispersion of each color was prepared by the following procedure and composition.

(Preparation of Blue Pigment Dispersion 1)
Instead of green pigment A, C.I. I. Blue Pigment Dispersion 1 was prepared in the same manner as Green Pigment Dispersion 13, except that Pigment Violet 23 (product name: Hostaperm Violet RL SP; manufactured by Clariant) was used. The obtained blue pigment dispersion 1 had a pigment content (solid content) of 10% by mass and a resin content of 9% by mass.

(Preparation of blue pigment dispersion 2)
Instead of green pigment A, C.I. I. Blue Pigment Dispersion 2 was prepared in the same manner as Green Pigment Dispersion 13 except that Pigment Blue 60 (product name: Miracet Blue R; manufactured by Ciba Specialty Chemicals) was used. The obtained blue pigment dispersion 2 had a pigment content (solid content) of 10% by mass and a resin content of 9% by mass.

(Preparation of Red Pigment Dispersion 1)
Instead of green pigment A, C.I. I. Red Pigment Dispersion 1 was prepared in the same manner as Green Pigment Dispersion 13, except that Pigment Red 149 (product name: Hostaprint Red B 32; manufactured by Clariant) was used. The obtained red pigment dispersion 1 had a pigment content (solid content) of 10% by mass and a resin content of 9% by mass.

(Preparation of Red Pigment Dispersion 2)
Instead of green pigment A, C.I. I. Red Pigment Dispersion 2 was prepared in the same manner as Green Pigment Dispersion 13, except that Pigment Red 177 (product name: Chromophthal Red A2B; manufactured by Ciba Specialty Chemicals) was used. The obtained red pigment dispersion 2 had a pigment content (solid content) of 10% by mass and a resin content of 9% by mass.

(Preparation of yellow pigment dispersion 1)
A pigment solution was prepared by mixing 10 parts of pigment, 9 parts of dispersant, and 81 parts of ion-exchanged water. The pigment includes C.I. I. Pigment Yellow 74 (product name: Hansa Brilliant Yellow 5GX; manufactured by Clariant) was used. The dispersant was obtained by neutralizing a random polymer having an acid value of 202 and a weight average molecular weight of 6,500, which was synthesized by a conventional method using styrene, butyl acrylate and acrylic acid as raw materials, with an aqueous potassium hydroxide solution. Resin F was used. This pigment solution was charged into a batch type vertical sand mill (manufactured by Imex), filled with 150 parts of 0.3 mm zirconia beads, and dispersed for 12 hours while cooling with water. Thereafter, coarse particles were removed by centrifugation. Further, the yellow pigment dispersion 1 having a pigment content (solid content) of 10% by mass and a resin content of 9% by mass by pressure filtration with a micro filter (manufactured by Fuji Film) having a pore size of 3.0 μm. Was prepared.

(Preparation of magenta pigment dispersion 1)
C. I. Pigment Yellow 74 instead of C.I. I. Magenta Pigment Dispersion 1 was prepared in the same manner as Yellow Pigment Dispersion 1, except that Pigment Red 122 (product name: Hostaper Pink E; manufactured by Clariant) was used and the dispersion time was 3 hours. The obtained magenta pigment dispersion 1 had a pigment content (solid content) of 10% by mass and a resin content of 9% by mass.

(Preparation of Cyan Pigment Dispersion 1)
C. I. Pigment Yellow 74 instead of C.I. I. Cyan Pigment Dispersion 1 was prepared in the same manner as Yellow Pigment Dispersion 1 except that Pigment Blue 15: 3 (product name: IRGALITE Blue 8700; manufactured by Ciba Specialty Chemicals) was used. The obtained cyan pigment dispersion 1 had a pigment content (solid content) of 10% by mass and a resin content of 9% by mass.

<Preparation of ink>
Ingredients shown in Tables 2 and 3 below were mixed and sufficiently stirred, and then pressure filtered through a micro filter (manufactured by Fuji Film) having a pore size of 1.0 μm to prepare inks 1 to 17. Inks 1 to 7 and 9 to 14 are inks of Examples of the present invention, Ink 8 is ink of Reference Example, and Inks 15 to 17 are inks of Comparative Example. In Tables 2 and 3, “resin MW” means the weight average molecular weight of the resin.

<Evaluation of green ink>
(1) Ejection stability Although the ink jet recording apparatus PIXUS990i (manufactured by Canon), which is filled with each ink obtained above and ejects ink by the action of thermal energy, has been modified to perform one-way recording. Installed in cyan ink position. Thereafter, a solid image of 2 cm × 8 cm was recorded on a PPC paper office planner (manufactured by Canon Inc.) while changing the recording duty in steps of 25, 50, 75, and 100%. At this time, the printer driver selected the default mode. The state of non-ejection, the density of the obtained solid image and the state of recording unevenness were visually observed to evaluate the ejection stability. The evaluation criteria for ejection stability are as follows. The evaluation results are shown in Table 4.

AA: There is no non-ejection up to a recording duty of 100%, and there is no recording unevenness at any recording duty.
A: There is no non-ejection up to a recording duty of 100%, but recording unevenness due to a deviation in the landing position occurs somewhat in an image with a recording duty of 25%.
B: There is no non-ejection up to the recording duty of 100%, but the landing position shifts in the image with the recording duty of 25%, and the image density decreases due to the decrease in the ejection volume in the image with the recording duty of 25%.
C: Non-ejection occurs at a recording duty of 100%, or there is no non-ejection at all nozzles, but the solid image is blurred.

(2) Storage stability Each ink obtained above was put in a glass bottle, sealed, and stored in an oven kept at a temperature of 60 ° C. for 3 months. Thereafter, the glass bottle was removed from the oven and allowed to stand until the ink reached room temperature. And the lid | cover of the bottle was made to stand down and the quantity and magnitude | size of the deposit | attachment in the bottom of a bottle were confirmed visually. Storage stability was evaluated by the difference in the amount and size of deposits before and after storage. Further, the viscosity of each ink before and after storage, the surface tension, the average particle diameter of the pigment, and the light absorption characteristics were measured by a conventional method to evaluate the storage stability. The evaluation criteria for storage stability are as follows. The evaluation results are shown in Table 4.

AA: Compared with the case before storage at 60 ° C., the amount and size of the deposits were not changed.
A: Compared with before storage at 60 ° C., the amount of deposits was not increased, but the size was slightly larger.
B: Although the amount of deposits was slightly increased compared with that before storage at 60 ° C., there was almost no change in the viscosity, surface tension, average particle diameter, and light absorption characteristics of the ink.
C: The amount of deposits is greatly increased as compared with that before storage at 60 ° C., and any of the viscosity, surface tension, average particle diameter, and light absorption characteristics of the ink is a value before storage at 60 ° C. It has changed compared to.

<Preparation of ink>
Ingredients shown in Table 5 below were mixed and sufficiently stirred, followed by pressure filtration with a microfilter (manufactured by Fuji Film) having a pore size of 1.0 μm to prepare inks 18 to 26.

In addition, about the diluted ink obtained by diluting the ink 18 with ion-exchange water 1,500 times (mass times), it is 400 nm or more and 700 nm using a spectrophotometer (brand name: U-3300, Hitachi, Ltd.). Absorbance was measured in the following range. As a result, the absorbance (B) at the maximum absorption wavelength in the range of 530 nm to 540 nm was 1.01, and the absorbance (B) at the maximum absorption wavelength in the range of 550 nm to 570 nm was 0.97. Therefore, the value of (B) / (A) was 0.96, which satisfied the condition of the following formula (1).

Moreover, about the diluted ink obtained by diluting the ink 22 and the ink 25 with ion-exchange water 1,000 times, respectively, using a spectrophotometer (trade name: U-3300, manufactured by Hitachi, Ltd.), the absorbance is measured. Went. The absorbance at each wavelength was summed from the absorption spectra of the obtained diluted inks. This was made into the absorption spectrum which added the light absorbency. At this time, in the absorption spectrum obtained by adding up the absorbance, the maximum absorbance (C) in the range from 450 nm to 570 nm was 1.91, and the minimum absorbance (D) was 1.61. Therefore, the value of (D) / (C) was 0.84, which satisfied the condition of the following formula (2).

<The combination of the ink which comprises the ink set of Example 15 and Reference Example 16, and Comparative Examples 4-7>
The inks 15 and 18 to 23 obtained above were used in the combinations shown in Table 6 below to obtain ink sets of Example 15, Reference Example 16, and Comparative Examples 4 to 7. The green pigment D used for the ink 15 is commercially available C.I. I. This corresponds to CI Pigment Green 7.

<Evaluation of ink sets of Example 15 and Reference Example 16 and Comparative Examples 4 to 7>
An ink jet recording apparatus PIXUS990i (manufactured by Canon Inc.) that fills an ink cartridge with each of the inks constituting the ink sets of Example 15 and Reference Example 16 and Comparative Examples 4 to 7 and discharges the ink by the action of thermal energy is used for one-way recording. It was mounted on what was modified to do. Then, a color chart of ISO / JIS-SCID high-definition color digital standard image was recorded. The recording conditions and recording media are as follows.

Recording conditions / paper type: Pro photo paper / Print quality: Fine / Color adjustment: Automatic recording medium / Professional photo paper PR-101 (Canon)

(1) Color reproduction range For the image obtained above, using Spectrolino (manufactured by Gretag Macbeth), the a ^* value and b ^* value in the L ^* a ^* b ^* color system defined by the CIE are measured. The a ^* value and b ^* value were plotted. And the color area of the image formed with the ink set of Example 15 and Reference Example 16 and each image formed with the ink set of Comparative Examples 4-7 was compared. As a result, the area of the color space of the image formed with the ink sets of Example 15 and Reference Example 16 was much larger than the area of the color space of each image formed with the ink sets of Comparative Examples 4-7.

(2) Color balance Using the Spectrolino (manufactured by Gretag Macbeth), the a ^* value and b ^* value in the L ^* a ^* b ^* color system defined by the CIE are measured for the image obtained above, and a ^* Values and b ^* values were plotted. And the color balance of the image formed with the ink set of Example 15 and Reference Example 16 and each image formed with the ink set of Comparative Examples 4-7 was confirmed visually, and compared. As a result, the color balance of each image formed with the ink sets of Comparative Examples 4 to 7 was locally saturated compared to the color balance of the images formed with the ink sets of Example 15 and Reference Example 16. There was a part that could not be done (part where the color balance was lost).

<Combination of inks constituting ink sets of Example 17 and Comparative Example 8>
The inks 18 to 26 obtained above were used in the combinations shown in Table 7 below to obtain ink sets of Example 17 and Comparative Example 8.

<Evaluation of Ink Sets of Example 17 and Comparative Example 8>
An ink jet recording apparatus PIXUS990i (manufactured by Canon Inc.) that refills ink cartridges with inks constituting the ink sets of Example 17 and Comparative Example 8 and discharges ink by the action of thermal energy was modified to perform one-way recording. Mounted on things. Then, a color chart of ISO / JIS-SCID high-definition color digital standard image was recorded. The recording conditions and recording media are as follows.

Recording conditions / paper type: Pro photo paper / Print quality: Fine / Color adjustment: Automatic recording medium / Professional photo paper PR-101 (Canon)

(1) Color reproduction range For the image obtained above, using Spectrolino (manufactured by Gretag Macbeth), the a ^* value and b ^* value in the L ^* a ^* b ^* color system defined by the CIE are measured. The a ^* value and b ^* value were plotted. The color areas of the image formed with the ink set of Example 17 and each image formed with the ink set of Comparative Example 8 were compared. As a result, the area of the color space of the image formed with the ink set of Example 17 was much larger than the area of the color space of each image formed with the ink set of Comparative Example 8.

(2) Color balance Using the Spectrolino (manufactured by Gretag Macbeth), the a ^* value and b ^* value in the L ^* a ^* b ^* color system defined by the CIE are measured for the image obtained above, and a ^* Values and b ^* values were plotted. And the color balance of the image formed with the ink set of Example 17 and each image formed with the ink set of Comparative Example 8 was confirmed visually and compared. As a result, the color balance of each image formed with the ink set of Comparative Example 8 is a portion where color saturation is not locally obtained (color balance) compared with the color balance of the image formed with the ink set of Example 17. There was a part that collapsed).

It is a perspective view of an inkjet recording device. It is a perspective view of the mechanism part of an inkjet recording device. It is sectional drawing of an inkjet recording device. FIG. 6 is a perspective view illustrating a state where an ink cartridge is mounted on the head cartridge. It is a disassembled perspective view of a head cartridge. FIG. 6 is a front view showing a recording element substrate in the head cartridge. It is a graph which shows an example of the result of the fluorescent X ray analysis of a green pigment.

Explanation of symbols

M2041: Separation roller M2060: Paper feed tray M2080: Paper feed roller M3000: Pinch roller holder M3030: Paper guide flapper M3040: Platen M3060: Transport roller M3070: Pinch roller M3110: Paper discharge roller M3120: Spur M3160: Paper discharge tray M4000: Carriage M5000: Pump M5010: Cap E0002: LF motor E0014: Electric substrate H1000: Head cartridge H1001: Recording head H1100: First recording element substrate H1101: Second recording element substrate H1200: First plate H1201: Ink supply port H1300: Electric wiring board H1301: External signal input terminal H1400: Second plate H1500: Tank holder H1501: Ink channel H1600: Channel type Member H1700: filter H1800: seal rubber H1900: ink cartridge H2000: yellow nozzle row H2100: magenta nozzle row H2200: cyan nozzle row H2300: Red nozzle row H2400: black nozzle row H2500: green nozzle row H2600: Blue nozzle row

Claims (8)

At least a water- based ink for inkjet comprising a green pigment having a copper phthalocyanine skeleton and a water-soluble organic solvent ,
The water-soluble organic solvent contains at least polyethylene glycol having a weight average molecular weight of 1,000 or more, and
A water-based ink, wherein a ratio of chlorine atom Kα ray intensity to bromine atom Kα ray intensity obtained by fluorescent X-ray analysis of the green pigment is 3.3 or more and 10.0 or less.   The water-based ink according to claim 1, wherein the water-based ink contains a resin having a weight average molecular weight in the range of 2,000 to 5,000. In an ink set for inkjet that is a combination of a plurality of water-based inks,
The plurality of water-based inks include at least a green ink, a red ink, and a blue ink,
The green ink contains at least a green pigment having a copper phthalocyanine skeleton, and the ratio of chlorine atom Kα ray intensity to bromine atom Kα ray intensity obtained by fluorescent X-ray analysis of the green pigment. Is a water-based ink that is 3.3 or more and 10.0 or less ,
The color material of the red ink is C.I. I. Pigment red 149,
The blue ink color material is C.I. I. An ink set, which is CI Pigment Violet 23. In an ink set for inkjet that is a combination of a plurality of water-based inks,
The plurality of water-based inks include at least a green ink, a red ink, and a blue ink,
The green ink is the water-based ink according to claim 1 or 2 ,
The color material of the red ink is C.I. I. Pigment red 149,
The blue ink color material is C.I. I. An ink set, which is CI Pigment Violet 23. In an inkjet recording method for recording on a recording medium by ejecting ink by an inkjet recording method, the ink is a water-based ink according to claim 1 or 2 , or a plurality of ink sets constituting an ink set according to claim 3 or 4. An ink jet recording method, characterized by being an ink. An ink cartridge comprising an ink containing portion for containing ink, wherein the ink is a water-based ink according to claim 1 or 2 or a plurality of inks constituting the ink set according to claim 3 or 4. Ink cartridge. In the recording unit provided with the ink storage part which stores ink, and the recording head which discharges ink, the said ink comprises the water-based ink of Claim 1 or 2 , or the ink set of Claim 3 or 4. A recording unit comprising a plurality of inks. An ink jet recording apparatus comprising an ink containing portion for containing ink and a recording head for ejecting ink, wherein the ink is the water-based ink according to claim 1 or 2 , or the ink set according to claim 3 or 4. An ink jet recording apparatus comprising a plurality of inks.

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