JP2008195794A - Black ink composition, ink cartridge, ink jet recording method and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a black ink composition giving a recorded matter having excellent hue and color development of a high-duty part on a glossy paper. <P>SOLUTION: The black ink composition at least contains water, a colorant expressed by formula (1) and a colorant expressed by formula (2). The compounding ratio of the colorant expressed by formula (1) to the colorant expressed by formula (2) is preferably (4-7):1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a black ink composition capable of obtaining a recorded matter excellent in hue and color development of a high duty part on glossy paper, an ink cartridge containing the black ink composition, and an ink jet recorded matter using the same. It relates to the manufacturing method.

  The ink jet recording method is a method of recording characters and figures on the surface of a recording medium such as paper by discharging ink droplets from a fine nozzle head. As an ink jet recording method, a piezoelectric element is used to convert an electrical signal into a mechanical signal, and ink droplets stored in the nozzle head portion are intermittently ejected to record characters and symbols on the surface of the recording medium. Part of the ink liquid is rapidly heated at a part close to the discharge part of the ink to generate bubbles, and ink droplets are intermittently discharged by the volume expansion caused by the bubbles to record characters and symbols on the surface of the recording medium. The method of doing is put into practical use.

  Ink for ink-jet recording is generally prepared by dissolving various dyes in water, organic solvents, or a mixture thereof from the viewpoint of safety and printing characteristics, but ink for writing instruments such as fountain pens and ballpoint pens. More stringent conditions are required compared to the composition.

In particular, black ink is required to have a high color developability at a so-called solid portion in order to improve the tightness of the image.
In such a background, various attempts have been made to improve image density (see Patent Documents 1 to 5).

In particular, in a high duty area, color saturation, that is, when the applied amount exceeds a certain level, it may become impossible to observe an increase in the density of the printed matter. If the final density in this case is low, the color developability deteriorates. This color saturation in the high duty portion is particularly noticeable when recording on glossy paper.
In this case, there is a problem that not only improvement in characteristics can be realized by simply increasing the color material concentration, but also the reliability of printing and clogging recovery is deteriorated due to an increase in solid portions in the ink.

JP 2000-290552 JP JP 2000-318300 A JP 2002-275380 A Japanese Patent Laid-Open No. 2003-292808 JP 2006-45538 A

  As described above, the conventional black ink composition has not been able to realize a recorded matter excellent in hue and color development of a high duty portion on glossy paper.

  Accordingly, an object of the present invention is to provide a black ink composition, an ink cartridge, and an ink jet recording method capable of obtaining a recorded material excellent in hue and color development of a high duty portion on glossy paper.

The inventors of the present invention provide a recorded matter excellent in hue and color development of a high duty portion on glossy paper by using a black ink composition containing at least water, a specific colorant, and a specific colorant as a complementary color. As a result, the present invention has been completed.
The reason why the remarkable effect by including such two specific colorants is achieved is not clear, but is presumed to be related to the penetration behavior of the colorant.

（式（１）中、Ｒ¹は置換基を有するフェニル基または置換基を有するナフチル基を表し、Ｒ²は置換基を有するフェニレン基または置換基を有するナフチレン基を表し、Ｒ³は少なくとも１つの二重結合及び置換基を有する５〜７員環の複素環基を表す。さらにＲ¹〜 Ｒ³における前記置換基は独立して、ＯＨ 、ＳＯ₃Ｍ 、ＰＯ₃Ｍ₂、ＣＯ₂Ｍ 、ＮＯ₂、Ｃ１〜４のアルキル基、置換されたアルキル基、Ｃ１〜４のアルコキシ基、置換されたアルコキシ基、置換されたアミノ基、及び置換されたフェニル基からなる群から選ばれる基を表す。ＭはＬｉ又はＮａを示す。）

（式（２）中、ＭはＬｉ又はＮａを示す。）；
〔２〕式（１）で表される着色剤と式（２）で表される着色剤との配合比が、４：１〜７：１である前記〔１〕に記載の黒色インク組成物；
〔３〕式（１）で表される着色剤の固形分濃度が、前記黒色インク組成物の総重量に対して５〜８重量％である前記〔１〕又は〔２〕に記載の黒色インク組成物；
〔４〕ノニオン系界面活性剤を含有する前記〔１〕〜〔３〕のいずれか一項に記載の黒色インク組成物；
〔５〕ノニオン系界面活性剤が、アセチレングリコール系界面活性剤である前記〔４〕に記載の黒色インク組成物；
〔６〕ノニオン系界面活性剤を０．１〜５重量％含有する前記〔４〕又は〔５〕に記載の黒色インク組成物；
〔７〕さらに、浸透促進剤を含有する前記〔１〕〜〔６〕のいずれか一項に記載の黒色インク組成物；
〔８〕浸透促進剤がグリコールエーテル類である前記〔７〕に記載の黒色インク組成物；
〔９〕インク組成物調整直後の２０℃におけるｐＨが７．０〜８．５である前記〔１〕〜〔８〕のいずれか一項に記載の黒色インク組成物；
〔１０〕ｐＨ調整剤として、有機酸及び／又は有機塩基を含有する前記〔１〕〜〔９〕のいずれか一項に記載の黒色インク組成物；
〔１１〕前記〔１〕〜〔１０〕のいずれか一項に記載された黒色インク組成物を独立に、または他色のインクと一体的に収容してなるインクカートリッジ；
〔１２〕前記〔１〕〜〔１１〕のいずれか一項に記載の黒色インク組成物の液滴を吐出し、該液滴を記録媒体に付着させて記録を行うインクジェット記録方法；
〔１３〕圧電素子の機械的変形によりインク滴を形成するインクジェットヘッドを用いた記録方法である前記〔１２〕に記載のインクジェット記録方法；
〔１４〕前記〔１２〕又は〔１３〕に記載されたインクジェット記録方法によって記録されたことを特徴とする記録物；を提供する。 That is, the present invention
[1] A black ink composition comprising at least water, a colorant represented by the following formula (1), and a colorant represented by the following formula (2):

(In Formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent, R ² represents a phenylene group having a substituent or a naphthylene group having a substituent, and R ³ is at least 1) Represents a 5- to 7-membered heterocyclic group having two double bonds and a substituent, and the substituents in R ¹ to R ³ are independently OH ₃ , SO ₃ M, PO ₃ M ₂ , CO ₂ M , NO ₂ , a group selected from the group consisting of a C1-4 alkyl group, a substituted alkyl group, a C1-4 alkoxy group, a substituted alkoxy group, a substituted amino group, and a substituted phenyl group. M represents Li or Na.)

(In formula (2), M represents Li or Na);
[2] The black ink composition according to [1], wherein a mixing ratio of the colorant represented by the formula (1) and the colorant represented by the formula (2) is 4: 1 to 7: 1. ;
[3] The black ink according to [1] or [2], wherein the solid content concentration of the colorant represented by the formula (1) is 5 to 8% by weight with respect to the total weight of the black ink composition. Composition;
[4] The black ink composition according to any one of [1] to [3], which contains a nonionic surfactant;
[5] The black ink composition according to [4], wherein the nonionic surfactant is an acetylene glycol surfactant;
[6] The black ink composition as described in [4] or [5] above, containing 0.1 to 5% by weight of a nonionic surfactant;
[7] The black ink composition according to any one of [1] to [6], further including a penetration accelerator;
[8] The black ink composition according to [7], wherein the penetration accelerator is a glycol ether;
[9] The black ink composition according to any one of [1] to [8], wherein the pH at 20 ° C. immediately after the ink composition is adjusted is 7.0 to 8.5;
[10] The black ink composition according to any one of [1] to [9], which contains an organic acid and / or an organic base as a pH adjuster;
[11] An ink cartridge containing the black ink composition described in any one of [1] to [10] independently or integrally with other color inks;
[12] An ink jet recording method for performing recording by discharging droplets of the black ink composition according to any one of [1] to [11] and attaching the droplets to a recording medium;
[13] The inkjet recording method according to [12], which is a recording method using an inkjet head that forms ink droplets by mechanical deformation of a piezoelectric element;
[14] A recorded matter recorded by the inkjet recording method described in [12] or [13].

  According to the method for producing a black ink composition, an ink cartridge, and an ink jet recorded product of the present invention, a recorded product excellent in hue and color developability of a high duty part on glossy paper can be obtained.

  Next, an embodiment of the present invention will be described. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. The present invention can be implemented in various forms without departing from the gist thereof.

（式（１）中、Ｒ¹は置換基を有するフェニル基または置換基を有するナフチル基を表し、Ｒ²は置換基を有するフェニレン基または置換基を有するナフチレン基を表し、Ｒ³は少なくとも１つの二重結合及び置換基を有する５〜７員環の複素環基を表す。さらにＲ¹〜 Ｒ³における前記置換基は独立して、ＯＨ 、ＳＯ₃Ｍ 、ＰＯ₃Ｍ₂、ＣＯ₂Ｍ 、ＮＯ₂、Ｃ１〜４のアルキル基、置換されたアルキル基、Ｃ１〜４のアルコキシ基、置換されたアルコキシ基、置換されたアミノ基、及び置換されたフェニル基からなる群から選ばれる基を表す。ＭはＬｉ又はＮａを示す。）

（式（２）中、ＭはＬｉ又はＮａを示す。） The black ink composition of the present invention contains at least water, a colorant represented by the following formula (1), and a colorant represented by the following formula (2).

(In Formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent, R ² represents a phenylene group having a substituent or a naphthylene group having a substituent, and R ³ is at least 1) Represents a 5- to 7-membered heterocyclic group having two double bonds and a substituent, and the substituents in R ¹ to R ³ are independently OH ₃ , SO ₃ M, PO ₃ M ₂ , CO ₂ M , NO ₂ , a group selected from the group consisting of a C1-4 alkyl group, a substituted alkyl group, a C1-4 alkoxy group, a substituted alkoxy group, a substituted amino group, and a substituted phenyl group. M represents Li or Na.)

(In formula (2), M represents Li or Na.)

According to the black ink composition, it is possible to obtain a recorded matter excellent in hue and color development of a high duty portion on glossy paper.
That is, the colorant represented by the formula (1) itself has a completely neutral hue, that is, an achromatic color, and generally has a bluish hue. In the present invention, the hue of the black ink composition can be adjusted by adding the colorant represented by the formula (2) to the colorant represented by the formula (1) as a complementary color dye. Excellent storage stability of images (image storage stability), and sufficient color density can be obtained. When other dyes are used as the complementary color dyes, the hue can be adjusted, but the effect of improving the color developability cannot be obtained, and the bronze phenomenon may occur at the same time.

Further, the substituted alkyl group is selected from C1-4 alkyl groups substituted with one or more groups selected from the group consisting of OH ₃ , SO ₃ M, PO ₃ M ₂ , and CO ₂ M groups. It is preferable that Also, substituted alkoxy groups mentioned, OH, is selected from _{SO 3 M, PO 3 M 2} , and C1~4 alkoxy group substituted with one or more groups selected from the group consisting of CO ₂ M It is preferable. The substituted amino group is a C1-4 alkyl group substituted with one or more groups selected from the group consisting of OH ₃ , SO ₃ M, PO ₃ M ₂ , and CO ₂ M. It is preferably selected from the group consisting of one or two amino groups. Further, the substituents phenyl groups are selected _{OH, SO 3 M, PO 3} M 2, CO 2 M, from the group consisting of alkyl groups and substituted C1~4 alkyl group, a C1~4 It is preferably selected from the group consisting of phenyl groups having one or two substituents.

  Specific examples of the colorant represented by the above formula (1) include colorants as shown in the following formulas (1-1) to (1-7). These colorants may be used alone or in combination of two or more.

（式（１−１）〜（１−７）中、Ｍは、Ｌｉ又はＮａを示す。ただし、全てのＭがＮａとなることはない。）

(In formulas (1-1) to (1-7), M represents Li or Na. However, not all M is Na.)

  The compounds represented by the above formula (1) or (1-1) to (1-7) can be appropriately synthesized by using a preferable method, and are, for example, bonded by three azo groups in each compound. It can be synthesized by combining building blocks having four corresponding structures by azo coupling.

The blending ratio (weight ratio) between the colorant represented by formula (1) and the colorant represented by formula (2) is not particularly limited, but is preferably 4: 1 to 7: 1.
If the blending ratio of either the colorant represented by the formula (1) and the colorant represented by the formula (2) is too large, the hue may not be neutral.

The solid content concentration of the colorant represented by the formula (1) is preferably 5 to 8% by weight with respect to the total weight of the black ink composition.
By setting such a solid content concentration, it is possible to achieve a high level of reliability such as color development and clogging on glossy paper. This is because, on glossy paper, only the colorant remaining in the vicinity of the glossy paper surface affects the color developability, and thus there is a certain saturation point in the effect of improving the color developability by increasing the solid content concentration. This is because the saturation point can be raised by combining the colorant represented by formula (2) with the colorant represented by formula (2).

  The black ink composition may contain a surfactant, a penetration enhancer, and other additives as necessary.

(Surfactant)
The black ink composition may contain a surfactant.
Examples of the surfactant include a nonionic surfactant, a cationic surfactant, and an anionic surfactant. Among these, the nonionic surfactant is a quick fixability of ink (permeability). And is an additive that is effective for maintaining the roundness of 1 dot, and is preferable.

Examples of the nonionic surfactant include acetylene glycol surfactants. Specific examples of the acetylene glycol surfactant include Surfynol 465, Surfynol 104 (above, manufactured by Air Products), Olphine STG, Olphine E1010 (above, manufactured by Nissin Chemical Industry Co., Ltd.), and the like. .
The addition amount of the nonionic surfactant in the black ink composition is 0. 1 to 5% by weight is preferable. 5 to 2% by weight is more preferable. If the addition amount of the nonionic surfactant in the black ink composition is 0.1% by weight or more, when recording, remarkable penetrability with respect to the recording material can be obtained, and 5% by weight or less. If so, the blur of the image can be kept good.

(Penetration enhancer)
The black ink composition may contain a penetration enhancer.
The penetration enhancer is not particularly limited, but glycol ethers are particularly preferable.
Examples of the glycol ethers include ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and triethylene. Examples include glycol monobutyl ether. Among these, triethylene glycol monobutyl ether is preferable.
If the addition amount of the penetration accelerator in the black ink composition is 3% by weight or more, bleeding of the black color material when performing solid printing can be prevented, and if it is 30% by weight or less, these Glycol ethers can be kept without oily separation.

(Other additives)
The black ink composition may contain a pH adjuster.
The pH adjuster is not particularly limited, and various compounds can be used. For example, inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid; inorganic bases such as lithium hydroxide, sodium hydroxide and potassium hydroxide Organic bases such as ammonia, triethanolamine, diethanolamine, monoethanolamine, and tri-iso-propanolamine; organic acids such as adipic acid, citric acid, and succinic acid. Among the above, the pH adjuster is preferably an organic acid and / or an organic base.
In particular, when an organic acid and an organic base are used in combination, the pH buffering capacity is greater than that of an inorganic acid and an inorganic base, an inorganic acid and an organic base, or an organic acid and an inorganic base. For this reason, when it combines and uses an organic acid and an organic base, there exists an effect that a pH fluctuation inhibitory effect is higher and it is easy to set to desired pH.

The black ink composition may contain a humectant.
Examples of the humectant include water-soluble organic solvents and saccharides, but water-soluble organic solvents are preferred from the viewpoint of the moisturizing effect.
The water-soluble organic solvent refers to a medium having the ability to dissolve solutes. Specifically, propylene glycol, butanediol, pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, diethylene glycol, triethylene glycol, Polyhydric alcohols such as dipropylene glycol and 1,2-alkanediol; alkyl alcohols such as methyl alcohol, ethyl alcohol, n-propylene alcohol and n-butyl alcohol; ketones such as acetonyl acetone; γ-butyrolactone, Examples include esters such as triethyl phosphate; furfuryl alcohol, tetrahydrofurfuryl alcohol, thiodiglycol, glycerin and the like. Among these, triethylene glycol, glycerin and 1,2-hexanediol are preferable.

An antioxidant / ultraviolet absorber can be added to the black ink composition.
The antioxidant / ultraviolet absorber is not particularly limited, and various compounds can be used. For example, allophanates such as allophanate and methylallohanate, biurets such as biuret, dimethylbiuret, and tetramethylbiuret. And L-ascorbic acid and its salts.

A preservative and fungicide can be added to the black ink composition.
The antiseptic / antifungal agent is not particularly limited, and various compounds can be used. For example, sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate , Sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN from Arch Chemicals) and the like.

The main solvent contained in the black ink composition is water.
As this water, ion exchange water, ultrafiltration water, reverse osmosis water, pure water such as distilled water, or ultrapure water can be used. In particular, it is preferable to use water sterilized by ultraviolet irradiation or addition of hydrogen peroxide in order to prevent the generation of mold and bacteria and enable long-term storage of the ink composition.

The black ink composition preferably has a pH of 7.0 to 8.5 at 20 ° C. immediately after adjustment of the ink composition. A more preferable pH range is 7.5 to 8.0.
The pH can be adjusted by adding the pH adjusting agent as necessary.
If the pH of the ink composition at 20 ° C. is too low, the eutectoid plating of the print head of the ink jet printer may be peeled off. If the pH is too high, the attack property to the ink contact member becomes strong or the stability of the ink Inferior in terms of sex. By adjusting the pH of the black ink composition at 20 ° C. to the above preferable range, the above-described problems are not caused, and the ejection characteristics and the storage stability of the black ink composition are improved.

(ink cartridge)
The ink cartridge of the present invention can be obtained by integrally storing the black ink compositions in a single container (cartridge) having a partition. Alternatively, the black ink compositions can be separately provided in separate containers. It can also be obtained in a (cartridge).
As the container, those generally used as an ink cartridge can be used, and among them, an ink cartridge for an ink jet printer is preferable.

(Manufacturing method of ink jet recorded matter)
The black ink composition can be suitably used for writing instruments such as pens, stamps and the like, but can be more suitably used as an ink composition for inkjet recording.
A method for producing an ink jet recorded material is a method of performing recording by ejecting the black ink composition as droplets from a fine nozzle and attaching the droplets to a recording medium, wherein the recording of the droplets is performed. This is particularly effective when the amount of driving into the medium is 1.5 to 2.2 mg / cm ² . A specific example will be described below.

  As a first method, there is an electrostatic suction method, in which a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, and ink is continuously ejected from the nozzle in the form of droplets. This is a method in which a print information signal is applied to the deflection electrode while the ink droplet is flying between the deflection electrodes for recording, or a method in which the ink droplet is ejected in response to the print information signal without being deflected.

  The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element (piezo element), in which a pressure and a print information signal are simultaneously applied to an ink liquid by a piezoelectric element, and ink droplets are ejected and recorded by mechanical deformation of the piezoelectric element.

  The fourth method is a method in which the ink liquid is rapidly expanded in volume by the action of heat energy, and the ink liquid is heated and bubbled by a microelectrode in accordance with a print information signal to eject and record ink droplets.

  Any of the above methods can be used in the ink jet recording method, and can be filled in the ink jet cartridge of each method.

(recoding media)
Further, the recording medium in this specification includes, for example, paper (Xerox P (trade name: manufactured by Fuji Xerox Co., Ltd.), Xerox 4024 (trade name: Xerox Co. (USA)), photographic paper crispia <high gloss> ( Product name: manufactured by Seiko Epson Corporation)) and the like, but is not particularly limited thereto.

(Recorded material)
Recording is performed by the ink jet recording method to obtain a recorded matter.
By using the above black ink composition, this recorded matter is excellent in hue and color developability of a high duty portion on glossy paper.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. Those skilled in the art can implement various modifications as well as the embodiments shown below, and such modifications are also included in the scope of the claims.

[Examples 1-4 and Comparative Examples 1-3]
Each component is mixed and dissolved at the blending ratio shown in Table 1, and pressure filtration is performed with a membrane filter having a pore diameter of 0.8 μm to prepare the black ink compositions of Examples 1 to 4 and Comparative Examples 1 to 3. did. In Table 1, the salt of Formula (1-1) and Formula (2) used what is Li: Na = 8: 2 (weight ratio).
Further, instead of the colorant of the formula (2), in Comparative Example 1, C.I. I. Direct Yellow 86 is a C.I. I. A black ink composition was prepared using Direct Red 227.

Using the ink jet printer PM-A700 (manufactured by Seiko Epson Corporation), the black ink composition described in Examples 1 to 4 and Comparative Examples 1 to 3 is filled into this dedicated cartridge (black). Specify the monochrome print setting on the printer driver for the inkjet recording medium “Photo Paper <Glossy>: Model No. KA420PSK (manufactured by Seiko Epson Corporation)” so that the shot amount is 1.5 to 2.2 mg / cm ^2. Solid print.

《Color development evaluation》
The OD value of each printed matter was measured using a densitometer (Spectroino: manufactured by Gretag).
The criteria for color development were determined as follows.
A: OD value 2.3 or more B: OD value 1.7 or more and less than 2.3 C: OD value 1.1 or more and less than 1.7 D: OD value less than 1.1

<Hue evaluation>
The hue was evaluated by visual observation as to whether it was close to an achromatic color. The evaluation is that “the most preferable hue” is the one that does not feel the most hue, the “preferable hue” is the one that feels a slight hue, and the “redness” is the one that clearly shows the red, green, and blue colors. ”,“ Green ”, and“ blue ”.

  The obtained results are shown in Table 2.

  As shown in Table 2, when recording was performed using the black ink composition of the example, the color developability was excellent.

Claims (14)

A black ink composition comprising at least water, a colorant represented by the following formula (1), and a colorant represented by the following formula (2).

(In Formula (1), R ¹ represents a phenyl group having a substituent or a naphthyl group having a substituent, R ² represents a phenylene group having a substituent or a naphthylene group having a substituent, and R ³ is at least 1) Represents a 5- to 7-membered heterocyclic group having two double bonds and a substituent, and the substituents in R ¹ to R ³ are independently OH ₃ , SO ₃ M, PO ₃ M ₂ , CO ₂ M , NO ₂ , a group selected from the group consisting of a C1-4 alkyl group, a substituted alkyl group, a C1-4 alkoxy group, a substituted alkoxy group, a substituted amino group, and a substituted phenyl group. M represents Li or Na.)

(In formula (2), M represents Li or Na.)   2. The black ink composition according to claim 1, wherein a mixing ratio of the colorant represented by the formula (1) and the colorant represented by the formula (2) is 4: 1 to 7: 1.   The black ink composition according to claim 1 or 2, wherein a solid content concentration of the colorant represented by the formula (1) is 5 to 8% by weight with respect to a total weight of the black ink composition.   The black ink composition as described in any one of Claims 1-3 containing a nonionic surfactant.   The black ink composition according to claim 4, wherein the nonionic surfactant is an acetylene glycol surfactant.   The black ink composition according to claim 4 or 5, which contains 0.1 to 5% by weight of a nonionic surfactant.   Furthermore, the black ink composition as described in any one of Claims 1-6 containing a penetration enhancer.   The black ink composition according to claim 7, wherein the penetration accelerator is a glycol ether.   The black ink composition according to any one of claims 1 to 8, wherein the pH at 20 ° C immediately after preparation of the ink composition is 7.0 to 8.5.   The black ink composition according to any one of claims 1 to 9, comprising an organic acid and / or an organic base as a pH adjuster.   An ink cartridge comprising the black ink composition according to claim 1 independently or integrally with ink of another color.   An ink jet recording method for performing recording by discharging a droplet of the black ink composition according to claim 1 and attaching the droplet to a recording medium.   The inkjet recording method according to claim 12, wherein the inkjet recording method uses an inkjet head that forms ink droplets by mechanical deformation of a piezoelectric element.   A recorded matter recorded by the ink jet recording method according to claim 12 or 13.