# Patent

## Title
Ink jet ink, method for producing ink jet ink, ink jet recording method and ink cartridge

## Abstract

An ink jet ink includes at least a coloring material. The coloring material is composed of at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure, and a compound represented by the following general formula (I) or a salt thereof

## Background
This application is a continuation of International Application No. PCT/JP2005/016196, filed Aug. 30, 2005, which claims the benefit of Japanese Patent Application Nos. 2004-252201, filed Aug. 31, 2004 and 2005-247599, filed Aug. 29, 2005.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet ink, a method for producing ink jet ink, an ink jet recording method and an ink cartridge.
2. Related Background Art
An ink jet recording method is a recording method of applying a small ink droplet to any one of recording media such as plain paper, glossy media and the like to form an image, has become rapidly widespread owing to reduction in its costs and improvement in its recording rate. In addition to improved quality of the recorded image, and concurrently with the rapid spread of digital cameras, users of the ink jet printers now demand to output recorded matter which is e comparable to a silver halide photograph.
A necessary requirement for a recorded matter which is obtained from an ink jet recording method to be comparable with a silver halide photograph, it is cited that both high color developability and durability of the obtained recorded matter are realized simultaneously. Compared with silver halide photographs, a recorded matter obtained from a conventional ink jet recording method has especially low durability, and when exposed for a long period of time to factors such as light, humidity, heat and environmental gases present in the air, the coloring material on the recorded matter would deteriorate. There has been, therefore, a problem that such recorded matters were susceptible to varying in color tone and fading of the image. Of the above-mentioned environmental gas, deterioration of the recorded matter from ozone is a particular problem.
Among the respective inks of yellow, magenta and cyan that are used in an ink jet recording method, cyan ink is the most susceptible to deterioration in durability (particularly ozone resistance). Thus, improving the ozone resistance of the cyan ink to match that of the yellow ink or magenta ink is an important matter.
The basic skeleton of coloring materials for ink jet ink having a cyan hue are roughly classified into a phthalocyanine skeleton and a triphenylmethane skeleton. Representative coloring materials of the former include C.I. Direct Blue 86 and 87, C.I. Direct Blue 199 and the like. Representative coloring materials of the latter include C.I. Acid Blue 9 and the like.
On the other hand, to improve environmental gas resistance, as represented by ozone resistance, inks which comprise a dye having a specific structure which exhibits extremely good environmental gas resistance have been proposed (e.g. see Japanese Patent No. 2942319).
SUMMARY OF THE INVENTION
As described above, there is a need for an ink jet ink which can provide images that have both high color developability and durability. However, regarding the color developability and durability of a recorded matter obtained from an ink jet recording method, there are users who are satisfied with the level of color developability and durability that can be obtained from a conventional ink jet ink.
In view of this, although there are at present a variety of recording media for ink jet recording method, it was discovered from investigations carried out by the present inventors that depending on the types of recording media and storage environment, a conventional ink jet ink may result in unsatisfactory color developability and durability even for such users.
Therefore, it turned out that it is necessary to improve the color developability and durability even in some degree over those of conventional ink jet inks.
Accordingly, an object of the present invention is to provide an ink jet ink which provides an image having excellent color developability and durability.
Another object of the present invention is to provide a method for producing an ink jet ink which provides images having excellent color developability and durability.
Still another object of the present invention is to provide an ink jet recording method and an ink cartridge which use the above-described ink jet ink.
The above objects are achieved by the following present invention. That is, the ink jet ink of the present invention comprises at least a coloring material, wherein the coloring material comprises at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure, and, a compound represented by the following general formula (I) or a salt thereof.




wherein l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 (provided that l+m+n=3 to 4); and a substitution position of a substituent is one of 4-position and 4′-position.

The method for producing an ink jet ink according to another embodiment of the present invention comprises a step of filling an ink jet ink tank which stores an ink jet ink comprising, as a coloring material, a compound represented by the following general formula (I) or a salt thereof, with an ink jet ink comprising, as a coloring material, at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure.




wherein l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 (provided that l+m+n=3 to 4); and a substitution position of a substituent is one of 4-position or 4′-position.

The ink jet ink according to another embodiment of the present invention is obtained by the method for producing an ink jet ink according to the above-described constitution.
The ink jet recording method according to another embodiment of the present invention comprises a step of ejecting an ink by ink jet method to conduct recording on a recording medium, wherein the ink is an ink jet ink according to the above-described constitution.
The ink cartridge according to another embodiment of the present invention comprises an ink storage portion for storing ink, wherein the ink comprises an ink jet ink according to the above-described constitution.
According to the present invention, an ink jet ink can be provided which provides images having excellent color developability and durability. Further, according to another embodiment of the present invention, a method for producing an ink jet ink can be provided which provides images having excellent color developability and durability. Further, according to another embodiment of the present invention, an ink jet recording method and an ink cartridge can be provided which use the above-described ink jet ink.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic explanatory diagram of a liquid-storing container (ink tank); and
FIG. 2 is a schematic explanatory diagram of another liquid-storing container (ink tank).



DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention will be described in more detail by way of preferred embodiments.
In the present invention, when a coloring material is a salt, the salt is dissociated into ions in ink, but this state is represented by using the phrase “contains a salt” for convenience.
<Ink>
The components and other substances which constitute the ink jet ink according to the present invention (hereinafter also referred to simply as “ink”) will be described below in detail.
(Coloring Material)
It is essential that the ink according to present invention comprise as a coloring material at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure. These coloring materials have excellent color developability, whereby images comparable to color developability of a silver-halide photograph can be formed by using an ink containing such a coloring material. To attain a good color developability in the present invention, the use of C.I. Direct Blue 199 as the compound having a copper phthalocyanine structure is especially preferable.
In addition to the above-described coloring materials, it is essential that the ink according to present invention comprise a compound represented by the following general formula (I) or a salt thereof. Since compounds represented by the below general formula (I) or a salt thereof have extremely high durability, the durability of the coloring material, which is at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure, can be improved even if they are contained in a minute amount in the ink. Further, a compound represented by the following general formula (I) or a salt thereof does not impair the excellent inherent color developability of the coloring material, which is at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure.
Specific examples of a counter ion in the salt of the compound represented by the general formula (I) include, for example, an alkali metal ion of lithium, sodium, potassium and the like, or an ammonium ion.




In the general formula (I), l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 (provided that l+m+n=3 to 4); and a substitution position of a substituent is one of 4-position or 4′-position.
The total content (mass %) of the coloring material in the ink according to the present invention is preferably from 0.1 mass % or more to 10.0 mass % or less with respect to the total mass of the ink. If the total content of the coloring material is less than 0.1 mass %, the durability and image density may not be sufficiently attained. If the total content of the coloring material exceeds 10.0 mass %, reliability as an ink jet ink, for instance sticking properties or similar properties, may be lowered. The content (mass %) of the compound represented by the general formula (I) or a salt thereof is preferably from 0.15 mass % or more to 2.0 mass % or less with respect to the total mass of the ink. If the content of the compound represented by the general formula (I) or salt thereof is less than 0.15 mass %, the durability may not be attained, whereas if it exceeds 2.0 mass %, the color developability may not be sufficiently attained. Further, the ratio of the content (mass %) of the compound represented by the general formula (I) or a salt thereof (mass %) to the total content of the coloring material is preferably from 9.0 mass % or more to 20.0 mass % or less. If the ratio is less than 9.0 mass %, the durability and image density may not be sufficiently attained, whereas if the ratio exceeds 20.0 mass %, the color developability may not be sufficiently attained.
It is noted that neither the upper limit of the content of the compound represented by the general formula (I) or a salt thereof, nor the upper limit of the content ratio of the compound represented by the general formula (I) or a salt thereof is particularly restricted. As long as the ink according to the present invention comprises at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure, it is preferable to incorporate therein more of the content and ratio of the compound represented by the general formula (I) or a salt thereof, in order to enhance the durability of the coloring materials.
(Method of Testing Coloring Material)
The compound represented by the general formula (I) or a salt thereof to be used in the present invention as a coloring material can be tested by following methods (1) to (3) each of which involves the use of high performance liquid chromatography (HPLC).

    (1) Retention time of a peak
    (2) Maximum absorption wavelength in the peak of (1)
    (3) M/Z (posi) of mass spectrum in the peak of (1)


Analysis conditions for high performance liquid chromatography are as shown below.
An ink solution diluted 50 times with pure water is analyzed by means of high performance liquid chromatography under the following conditions to measure the retention time of a peak and the maximum absorption wavelength of the peak.
Column: Symmetry C18 2.1 mm×150 mm
Column temperature: 40° C.
Flow rate: 0.2 ml/min
PDA: 210 nm to 700 nm
Mobile phase and gradient condition: Table 1










TABLE 1







0-15 min
15-30 min




















A Water
87.5% −> 0%
  0%



B Acetonitrile
10% −> 97.5%
97.5%



C 0.2 mol/l Ammonium
2.5%
 2.5%



acetate aqueous



solution










In addition, analysis conditions for mass spectrum are as shown below.
The mass spectrum of the resultant peak is measured under the following conditions, and the M/Z (posi) was measured.
Ionization Method

















ESI
Capillary voltage
3.5 kV




Desolvating gas
300° C.




Ion source temperature
120° C.










Detector
posi 40 V 500-2,000 amu/0.9 sec










Table 2 shows the values of the retention time, maximum absorption wavelength and M/Z (posi) of the compound represented by the general formula (I) or a salt thereof. When a compound has a value shown in Table 2, the compound can be determined to be a compound used in the present invention. In the coloring materials used in the present invention, the peak ratio of the mass spectrum obtained from a peak of the high-performance liquid chromatography (HPLC) varies depending on a mixing ratio of isomers different from each other in number, kinds, and substitution positions of substituents in the coloring material, but the peak of M/Z described in Table 2 below is characterized in that it is always detected. Therefore, the present method of testing a coloring material is effective in examining whether ink contains the coloring material used in the present invention.









TABLE 2





Retention
Maximum absorption



time [min]
wavelength [nm]
M/Z







6.9-7.2
600-620
1670-1672









(Other Coloring Materials)
In the present invention, other coloring materials may also be used in combination with at lease one selected from the group consisting of C.I. Acid Blue 9 and a copper phthalocyanine structure, and the compound represented by the general formula (I) or a salt thereof.
In addition, an ink having a color tone different from that of the ink according to the present invention may also be used in combination therewith in order to form full color images. Such an ink may be, for example, cyan ink, magenta ink, yellow ink, black ink and the like. Light-color inks having the same color tone as these inks may also be used in combination. Known coloring materials or newly synthesized coloring materials may be employed as a coloring material for an ink or light-color ink having such a different color tone.
Specific examples of coloring materials for color toning and coloring materials used in the other inks employed together with the ink according to the present invention will be shown according to their color tone. The present invention is, of course, not limited to these examples.
(Magenta Coloring Materials)
C.I. Direct Red 2, 4, 9, 11, 20, 23, 24, 31, 39, 46, 62, 75, 79, 80, 83, 89, 95, 197, 201, 218, 220, 224, 225, 226, 227, 228, 229, 230 and the like; C.I. Acid Red 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 42, 51, 52, 80, 83, 87, 89, 92, 106, 114, 115, 133, 134, 145, 158, 198, 249, 265, 289 and the like; C.I. Food Red 87, 92, 94 and the like; C.I. Direct Violet 107 and the like; C.I. Pigment Red 2, 5, 7, 12, 48:2, 48:4, 57:1, 112, 122, 123, 168, 184, 202 and the like.
(Cyan Coloring Materials)
C.I. Direct Blue 1, 15, 22, 25, 41, 76, 80, 90, 98, 106, 108, 120, 158, 163, 168, 199, 226 and the like; C.I. Acid Blue 1, 7, 15, 22, 23, 25, 29, 40, 43, 59, 62, 74, 78, 80, 90, 100, 102, 104, 117, 127, 138, 158, 161, 203, 204, 244 and the like; C.I. Pigment Blue 1, 2, 3, 15, 15:2, 15:3, 15:4, 16, 22, 60 and the like.
(Yellow Coloring Materials)
C.I. Direct Yellow 8, 11, 12, 27, 28, 33, 39, 44, 50, 58, 85, 86, 87, 88, 89, 98, 100, 110, 132, 173 and the like; C.I. Acid Yellow 1, 3, 7, 11, 17, 23, 25, 29, 36, 38, 40, 42, 44, 76, 98, 99 and the like; C.I. Pigment Yellow 1, 2, 3, 12, 13, 14, 15, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 138, 180 and the like.
(Orange Coloring Materials)
C.I. Acid Orange 7, 8, 10, 12, 24, 33, 56, 67, 74, 88, 94, 116, 142 and the like; C.I. Acid Red 111, 114, 266, 374 and the like; C.I. Direct Orange 26, 29, 34, 39, 57, 102, 118 and the like; C.I. Food Orange 3 and the like; C.I. Reactive Orange 1, 4, 5, 7, 12, 13, 14, 15, 16, 20, 29, 30, 84, 107 and the like; C.I. Disperse Orange 1, 3, 11, 13, 20, 25, 29, 30, 31, 32, 47, 55, 56 and the like; C.I. Pigment Orange 43 and the like; C.I. Pigment Red 122, 170, 177, 194, 209, 224 and the like.
(Green Coloring Materials)
C.I. Acid Green 1, 3, 5, 6, 9, 12, 15, 16, 19, 21, 25, 28, 81, 84 and the like; C.I. Direct Green 26, 59, 67 and the like; C.I. Food Green 3 and the like; C.I. Reactive Green 5, 6, 12, 19, 21 and the like; C.I. Disperse Green 6, 9 and the like; C.I. Pigment Green 7, 36 and the like.
(Blue Coloring Materials)
C.I. Acid Blue 62, 80, 83, 90, 104, 112, 113, 142, 203, 204, 221, 244 and the like; C.I. Reactive Blue 49 and the like; C.I. Acid Violet 17, 19, 48, 49, 54, 129 and the like; C.I. Direct Violet 9, 35, 47, 51, 66, 93, 95, 99 and the like; C.I. Reactive Violet 1, 2, 4, 5, 6, 8, 9, 22, 34, 36 and the like; C.I. Disperse Violet 1, 4, 8, 23, 26, 28, 31, 33, 35, 38, 48, 56 and the like; C.I. Pigment Blue 15:6 and the like; C.I. Pigment Violet 19, 23, 37 and the like.
(Black Coloring Materials)
C.I. Direct Black 17, 19, 22, 31, 32, 51, 62, 71, 74, 112, 113, 154, 168, 195 and the like; C.I. Acid Black 2, 48, 51, 52, 110, 115, 156 and the like; C.I. Food Black 1, 2 and the like; carbon black and the like.
(Aqueous Medium)
The ink according to the present invention can use water or an aqueous medium which is a mixed solvent of water and various water-soluble organic solvents.
The water-soluble organic solvent is not restricted as long as the solvent is soluble in water. Examples of solvents which can be used include alkyl alcohols having 1 to 4 carbon atoms, such as ethanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol; carboxylic acid amides such as N,N-dimethylformamide or N,N-dimethylacetamide; ketones and ketoalcohols such as acetone, methyl ethyl ketone and 2-methyl-2-hydroxypentan-4-one; cyclic ethers such as tetrahydrofuran and dioxane; polyalcohols such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2- or 1,3-propylene glycol, 1,2 or 1,4-butylene glycol, polyethylene glycol, 1,3-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, dithioglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives and trimethylolpropane; polyalcohol alkyl ethers such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, and triethylene glycol monoethyl (or butyl) ether; heterocycles such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and N-methylmorpholine; sulfur-containing compounds such as dimethylsulfoxide; and urea and urea derivatives. Each of those water-soluble organic solvents may be used alone, or two or more of them may be used as a mixture.
The content of such water-soluble organic solvent is preferably from 5.0 mass % to 90 mass %, more preferably from 10.0 mass % to 50.0 mass % with respect to the total mass of the ink. If the content is less than this range, there is a possibility that reliability, such as ejection properties, is lowered when used for an ink jet ink. If the content exceeds this range, there is a possibility that a problem may occur in ink supply due an increase in ink viscosity.
Deionized water (ion-exchanged water) is preferably used as water. The content of water is preferably from 10.0 mass % to 90.0 mass % with respect to the total mass of the ink.
(Other Additives)
In the present invention, various other additives, such as a surfactant, pH adjuster, chelating agent, corrosion inhibitor, preservative, mildew-proof agent, ultraviolet absorber, viscosity adjuster, defoaming agent and water-soluble polymer, may also be incorporated as needed.
Specific examples of a surfactant include anionic surfactants, ampholytic surfactants, cationic surfactants and nonionic surfactants.
Specific examples of anionic surfactants include alkyl sulfocarboxylate, α-olefin sulfonate, polyoxyethylene alkyl ether acetate, N-acylamino acid and salts thereof, N-acylmethyltaurine salts, alkyl sulfate polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate, lauryl alcohol sulfate, alkylphenol phosphate, alkyl phosphate, alkylaryl sulfonate, diethyl sulfosuccinate, diethylhexyl sulfosuccinate and dioctyl sulfosuccinate.
Specific examples of cationic surfactants include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.
Specific examples of amphoteric surfactants include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, palm oil fatty acid amidopropyldimethylaminoacetic acid betaines, polyoctylpolyaminoethyl glycine and other imidazoline derivatives.
Specific examples of nonionic surfactants include ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether and polyoxyarylkyl alkyl ether; esters such as polyoxyethylene oleic acid, polyoxyethylene oleic acid ester, polyoxyethylene distearic acid ester, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate and polyoxyethylene stearate; and acetylene glycols (e.g. Acetylenol EH and E100 manufactured by Kawaken Fine Chemicals Co., Ltd., and Surfynol 104, 82 and 465 and olfin STG manufactured by Nisshin Chemical Co., Ltd.) such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol and 3,5-dimethyl-1-hexyn-3-ol.
Any substance may be used as the pH adjuster as long as it can adjust the pH of the ink to a certain range. Examples of such substance include alcohol amine compounds such as diethanol amine, triethanol amine, isopropanol amine and trishydroxymethylamino methane; alkali metal hydroxides such as lithium hydroxide and potassium hydroxide; ammonium hydroxide; or alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate.
Specific examples of the preservative and the mildew-proof agent include, for example, organosulfur, organic nitrogen-sulfur, organohalogen, haloallylsulfone, iodopropargyl, N-haloalkylthio, benzothiazole, nitrile, pyridine, 8-oxyquinoline, benzothiazole, isothiazolin, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiadiazine, anilide, adamantane, dithiocarbamate, brominated indanone, benzylbromoacetate, and inorganic salt compounds.
Examples of an organohalogen compound include, for example, sodium pentachlorophenol, and examples of a pyridine compound include, for example, sodium 2-pyridinethiol-1-oxide. Examples of an inorganic salt compound include, for example, acetic anhydride soda, and examples of an isothiazolin compound include, for example, 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one magnesium chloride and 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride. Other specific examples of the preservative and the mildew-proof agent include sorbic acid soda and sodium benzoate, for example, Proxel GXL (S), Proxel XL-2 and the like manufactured by Avecia Limited.
Examples of a chelating agent include, for example, sodium citrate, sodium ethylenediaminetetraacetate, sodium sec-nitrotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate and sodium uramildiacetate.
Examples of the corrosion inhibitor include, for example, acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate and dicyclohexyl ammonium nitrite.
Examples of the ultraviolet absorber compound include, for example, compounds which absorb ultraviolet light and emit fluorescence as represented by benzophenone compounds, benztriazole compounds, cinnamic acid compounds, triazine compounds, stilbene compounds or benzoxazole compounds. What is called a fluorescent brightening agent may also be used.
In addition to the water-soluble organic solvents, examples of a viscosity adjuster include water-soluble polymeric compounds such as polyvinylalcohols, cellulose derivatives, polyamine and polyimines.
A fluorine or silicone compound may be employed as the defoaming agent as necessary.
<Ink Jet Recording Method>
The ink according to the present invention is particularly suitably used for an ink jet recording method comprising a step of ejecting ink by ink jet method. Examples of the ink jet recording method include a recording method which ejects ink by applying mechanical energy to the ink, and a recording method which ejects ink by applying thermal energy to the ink. In particular, in the present invention, an ink jet recording method in which thermal energy is utilized can be preferably used.
<Ink Cartridge>
An example of an ink cartridge suitable for conducting recording by using the ink according to the present invention includes an ink cartridge which is provided with an ink storage portion for storing the ink. Specific examples of such an ink cartridge will be described below.
FIG. 1 is a schematic explanatory view of a liquid-storing container serving as an ink cartridge. In FIG. 1, the liquid-storing container (ink tank) has a structure such that it is in communication with the atmosphere at an upper section via an air communication opening 112, is in communication with an ink supply port at a lower section, and is partitioned by a partitioning wall 138 into a negative-pressure generation member holding chamber 134, which holds a negative-pressure generation member, and a liquid-storing chamber 136, which is essentially sealed, that stores the liquid ink. The negative-pressure generation member holding chamber 134 and the liquid-storing chamber 136 are in communication with each other only through a communication hole 140 formed in the partitioning wall 138 near a bottom section of the liquid-storing container (ink tank), and an air lead-in groove (air lead-in path) 150, whose purpose is to promote the introduction of air into the liquid-storing chamber during liquid supply operation. A plurality of ribs are formed in an integrated manner on an upper wall of the liquid-storing container (ink tank) which forms the negative-pressure generation member holding chamber 134 so as to project into the inside, wherein the ribs are brought into contact with the negative-pressure generation member, which is held in a compressed state, in the negative-pressure generation member holding chamber 134. These ribs form an air buffer chamber between the upper wall and an upper surface of the negative-pressure generation member. A pressure contact member 146 which has greater capillary force than the negative-pressure generation member and possesses great physical strength, is provided on an ink supply pipe provided with a liquid-supply port 114, whereby the ink supply pipe is brought into pressure contact with the negative-pressure generation member.
Two capillary force generation type negative-pressure generation members, composed of a first negative-pressure generation member 132B and a second negative-pressure generation member 132A made from an olefin resin fiber such as polyethylene, are held as the negative-pressure generation members in the negative-pressure generation member holding chamber 134. The member 132C is a boundary layer between these two negative-pressure generation members, wherein the intersection of the boundary layer 132C with the partitioning wall 138 exists above the upper edge of the air lead-in groove (air lead-in path) 150 in the configuration in which the liquid-storing container is being used with its communication part positioned downward. The ink held in the negative-pressure generation members is present at a level higher than the above-described boundary layer 132C, as indicated by the liquid surface L of the ink.
Here, the first negative-pressure generation member 132B is brought into pressure contact with the boundary layer of the second negative-pressure generation member 132A, so that the compression ratio in the vicinity of the boundary layer of the negative-pressure generation members is higher than that in the other sections, whereby strong capillary force is generated. That is, if the capillary force of the first negative-pressure generation member 132B is represented by P1, the capillary force of the second negative-pressure generation member 132A by P2 and the capillary force possessed by the interface between the negative-pressure generation members by PS, the relationship P2<P1<PS is satisfied.
FIG. 2 is a schematic explanatory view of a liquid-storing container which is another ink cartridge. The liquid-storing container (ink tank) illustrated in FIG. 2 has a container 41 for storing three colors of inks (yellow (Y), magenta (M) and cyan (C)), and a cap member 42 which covers the container 41. The interior of the container 41 is partitioned into three spaces which have an approximately equal capacity by two partitioning plates 411 and 412 disposed parallel to each other for storing the three ink colors. These three spaces are aligned in the direction in which the ink tank is inserted when mounting the ink tanks onto an ink tank holder. Theses three spaces hold respectively an ink absorbing body 44Y for absorbing and retaining a yellow ink, an ink absorbing body 44M for absorbing and retaining a magenta ink, and an ink absorbing body 44C for absorbing and retaining a cyan ink. The inks held in these absorbing bodies 44Y, 44M and 44C, which act as negative-pressure generation members, are present at a level higher than the upper sections of the respective absorbing bodies, as indicated by the liquid surface L of the ink.
In FIG. 2, the reference characters 43Y, 43M and 43C, as well as 45Y, 45M and 45C, denote respectively yellow (Y), magenta (M) and cyan (C) ink supply ports and ink supply members of the three colors of inks. Further, reference characters 46, 47, 47C, 48 and 49 denote respectively a retaining claw, a latch lever, a bottom incline, a latch claw and a bump portion.
<Method for Producing Ink Jet Ink>
There is no specific limitation concerning the method for producing the ink jet ink according to the present invention, as long as the constitutional requirements necessary for the ink according to the present invention are satisfied, i.e. provided that the ink contains, as a coloring material, at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure, and, a compound represented by the general formula (I) or a salt thereof.
In the present invention, it is particularly preferable that the method has a step of filling an ink tank storing an ink in which a compound represented by the general formula (I) or a salt thereof is contained as a coloring material, with the ink containing, as a coloring material, at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure. This is because it is possible to reduce costs through the reuse of an ink containing a compound represented by the general formula (I) or a salt thereof, which has excellent durability, and an ink cartridge which stores such ink. In addition to the above advantages, this is also because an ink cartridge which has once stored ink can provide such an accompanying advantage that ink refill is easy.
EXAMPLES
Hereinafter, the present invention will be described in more detail by way of examples and comparative examples. However, the present invention is not limited to the following examples unless the examples depart from the gist of the present invention. Unless otherwise specified, the term “part(s)” of each ink component in examples and comparative examples represents “part(s) by mass”.
<Synthesis Coloring Material>
(1) Synthesis of Tetrasodium Copper Phthalocyanine Tetrasulfonate (Compound (2))




Sulfolane, monosodium 4-sulfophthalate, ammonium chloride, urea, ammonium molybdate, and copper (II) chloride were mixed, stirred, and washed with methanol. After that, water was added to the resultant product, and an aqueous solution of sodium hydroxide was used to adjust the pH of the solution to 11. An aqueous solution of hydrochloric acid was added to the resultant solution under stirring, and then sodium chloride was gradually added to precipitated crystals. The resultant crystals were filtered and washed with a 20% aqueous solution of sodium chloride, and then methanol was added. The separated out crystals were filtered out, washed with a 70% aqueous solution of methanol, and dried to yield tetrasodium copper phthalocyanine tetrasulfonate (Compound (2)) as blue crystals.
(2) Synthesis of Copper Phthalocyanine Tetrasulfonic Chloride (Compound (3))




Tetrasodium copper phthalocyanine tetrasulfonate (Compound (2)) thus prepared was gradually added to chlorosulfonic acid, and then thionyl chloride was added dropwise to perform reaction. After that, the reaction solution was cooled, and the precipitated crystals were filtered out to prepare a wet cake of copper phthalocyanine tetrasulfonic chloride.
(3) Synthesis of the Following Compound (4)




Lipal OH, cyanuric chloride, and monosodium aniline-2,5-disulfonate were added in an ice water, and was allowed to react while an aqueous solution of sodium hydroxide was added. Next, an aqueous solution of sodium hydroxide was added to the reaction solution to adjust the pH of the reaction solution to 10. 28% ammonia water and ethylenediamine were added to the reaction solution to perform a reaction. The precipitated crystals were filtered out and fractionated, and was washed with a 20% aqueous solution of sodium chloride to prepare a wet cake. Methanol and water were added to the resultant wet cake, and the whole was filtered, washed with methanol, and dried to yield the compound (4).
(4) Synthesis of the Compound Represented by the General Formula (I)
The wet cake of copper phthalocyanine tetrasulfonic chloride (Compound (3)) obtained in the above (2) was added to an ice water, and the whole was stirred to prepare a suspension. Ammonia water and the compound (4) synthesized in (3) were added to the suspension to perform a reaction. The resultant crystals were filtered, washed with an aqueous solution of sodium chloride, and filtered again, washed, and dried to yield a compound represented by the general formula (I) as blue crystals. In view of the above reaction, the compound is estimated to be a compound represented by the general formula (I) (sodium salt) and has average numbers of substituents in the general formula (I) of l=1.0 to 1.5, m=1.5 to 2.0 and n=2.0 to 2.5.
<Preparation of Ink>
The respective components shown in each of Tables 3 and 4 below were mixed and sufficiently stirred. After that, the resultant was filtered through a filter having a pore size of 0.2 μm under pressure to prepare each of inks of Examples 1 to 6 and Comparative Examples 1 to 4.









TABLE 3









Example














1
2
3
4
5
6

















C. I. Direct Blue 199
1.50

1.50

4.00



C. I. Acid Blue 9

1.50

1.50

4.00


Compound represented by the
0.14
0.14
0.15
0.15
0.60
0.60


general formula (I)


Glycerin
20.00
20.00
20.00
20.00
20.00
20.00


Acetylenol EH
1.00
1.00
1.00
1.00
1.00
1.00


Ion-exchange water
77.36
77.36
77.35
77.35
74.40
74.40



















TABLE 4









Comparative Example













1
2
3
4















C. I. Direct Blue 199
1.50

4.00



C. I. Acid Blue 9

1.50

4.00


Compound represented


by the general formula (I)


Glycerin
20.00
20.00
20.00
20.00


Acetylenol EH
1.00
1.00
1.00
1.00


Ion-exchange water
77.50
77.50
75.00
75.00









<Evaluation of Ink>
The above-obtained inks were each filled into an ink tank having the structure of FIG. 1. These ink tanks were mounted onto an ink jet recording apparatus (trade name: PIXUS 950i, manufactured by Canon Inc.) in which thermal energy was applied to the ink for ejecting ink droplets to conduct printing, where the recording conditions at this time were as follows: temperature of 23° C., humidity of 55%, recording density of 2400 dpi×1200 dpi and an ink ejection volume of 2.5 pl, and recording was conducted at a 50% duty on a recording medium (trade name: PR-101, manufactured by Canon Inc.). The obtained recorded matters were subsequently air dried for 24 hours at a temperature of 23° C. and a humidity of 55%.
The color developability of the recorded matters obtained using the inks of Examples 1 to 6 was visually evaluated from the viewpoint of comparison with inks containing ion-exchange water in place of the compound represented by the general formula (I) (i.e. Examples 1 and 3 were compared with Comparative Example 1; Examples 2 and 4 with Comparative Example 2; Example 5 with Comparative Example 3; and Example 6 with Comparative Example 4).
Next, the above air-dried recorded matters were placed in an ozone testing apparatus (trade name: OMS-H, manufactured by Suga Test Instruments Co., Ltd.), and subjected to ozone exposure for 20 hours in an environment (temperature: 40° C.; humidity: 55%; ozone gas concentration: 2 ppm).
The ozone resistance of recorded matters obtained using the inks of Examples 1 to 6 was visually evaluated from the viewpoint of comparison with an ink containing ion-exchange water in place of the compound represented by the general formula (I) (i.e. Examples 1 and 3 were compared with Comparative Example 1; Examples 2 and 4 with Comparative Example 2; Example 5 with Comparative Example 3; and Example 6 with Comparative Example 4).
The evaluation criteria for color developability and ozone resistance were as described below. The evaluation results are shown in Table 5.
A: Either color developability or ozone resistance was clearly improved over the Comparative Examples, and, neither color developability nor ozone resistance deteriorated as compared with the Comparative Examples.
B: Either color developability or ozone resistance was improved over the Comparative Examples, and, neither color developability nor ozone resistance deteriorated as compared with the Comparative Examples.
C: Neither color developability nor ozone resistance showed any improvement over the Comparative Examples, or, although one of color developability or ozone resistance was improved over the Comparative Examples, either of color developability or ozone resistance deteriorated as compared with the Comparative Examples.










TABLE 5








Evaluation



Example
Results









1
B



2
B



3
A



4
A



5
A



6
A










<Preparation of Ink>
The respective components shown in Table 6 below were mixed and sufficiently stirred. After that, the resultant was filtered through a filter having a pore size of 0.2 μm under pressure to prepare an ink.










TABLE 6









Compound Represented by
6.00



the General Formula (I)



Glycerin
20.00



Acetylenol EH
1.00



Ion-Exchange Water
73.00










Ink tanks having the structure illustrated in FIG. 1 were filled with 14.5 g of an ink prepared according to the formulation shown in Table 6. Then, 12.5 g of ink was discharged from each of the ink tanks. Subsequently, the above ink tanks were each filled with 10.0 g of the respective inks prepared in Comparative Examples 3 and 4, whereby the inks for Examples 7 and 8 were prepared. The inks of Examples 7 and 8 were extracted from the ink tanks. Analysis of their composition showed that these inks had a composition as shown in Table 7.










TABLE 7









Example











7
8













C. I. Direct Blue 199
3.33



C. I. Acid Blue 9

3.33


Compound Represented by
1.00
1.00


the General Formula (I)


Glycerin
20.00
20.00


Acetylenol EH
1.00
1.00


Ion-Exchange Water
74.67
74.67









<Evaluation of Ink>
The above-obtained inks of Example 7 and 8 were filled into ink tanks. These ink tanks were mounted onto an ink jet recording apparatus (trade name PIXUS 950i, manufactured by Canon Inc.) in which thermal energy was applied to the ink for ejecting ink droplets to conduct recording, where the recording conditions at this time were as follows: temperature of 23° C., humidity of 55%, recording density of 2400 dpi×1200 dpi and ink ejection volume of 2.5 pl, and recording was conducted at a 50% duty on a recording medium (trade name: PR-101, manufactured by Canon Inc.). The obtained recorded matters were subsequently air dried for 24 hours at a temperature of 23° C. and a humidity of 55%.
The color developability of the recorded matters obtained using the inks of Examples 7 and 8 was visually evaluated from the viewpoint of comparison with inks containing ion-exchange water in place of the compound represented by the general formula (I) (for the inks of Examples 7 and 8 were compared with the inks of Comparative Examples 5 and 6 which contained ion-exchange water in place of the compound represented by the general formula (I); Example 7 with Comparative Example 5; and Example 8 with Comparative Example 6).
Next, the above air-dried recorded matters were placed in an ozone testing apparatus (trade name: OMS-H, manufactured by Suga Test Instruments Co., Ltd.), and subjected to ozone exposure for 20 hours in an environment (temperature: 40° C.; humidity: 55%; ozone gas concentration: 2 ppm).
The ozone resistance of recorded matters obtained using the inks of Examples 7 and 8 was visually evaluated from the viewpoint of comparison with inks containing ion-exchange water in place of the compound represented by the general formula (I) (for the inks of Examples 7 and 8 were compared with the inks of Comparative Examples 5 and 6 which contained ion-exchange water in place of the compound represented by the general formula (I); Example 7 with Comparative Example 5; and Example 8 with Comparative Example 6).
The evaluation criteria for color developability and ozone resistance are as described below. The evaluation results are shown in Table 8.
A: Either color developability or ozone resistance was clearly improved over the Comparative Examples, and, neither color developability nor ozone resistance deteriorated as compared with the Comparative Examples.
B: Either color developability or ozone resistance was improved over the Comparative Examples, and, neither color developability nor ozone resistance deteriorated as compared with the Comparative Examples.
C: Neither color developability nor ozone resistance showed any improvement over the Comparative Examples, or, although one of color developability or ozone resistance was improved over the Comparative Examples, either of color developability or ozone resistance deteriorated as compared with the Comparative Examples.










TABLE 8








Evaluation



Example
Results









7
B



8
B










The present application claims priorities from Japanese Patent Application No. 2004-252201 filed on Aug. 31, 2004, and Japanese Patent Application No. 2005-247599 filed on Aug. 29, 2005, which are hereby incorporated by reference herein.

## Claims

1. An ink jet ink comprising at least a coloring material,
wherein the coloring material comprises at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure, and a compound represented by the following general formula (I) or a salt thereof




 wherein l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 provided that l+m+n=3 to 4; and a substitution position of a substituent is one of 4-position and 4′-position; and
wherein the content (mass %) of the compound represented by the general formula (I) or a salt thereof is less than the content (mass %) of the at least one selected from the group.

2. A method for producing an ink jet ink comprising a step of filling an ink jet ink tank which stores an ink jet ink comprising, as a coloring material, a compound represented by the following general formula (I) or a salt thereof, with an ink jet ink comprising, as a coloring material, at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure



wherein l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 provided that l+m+n=3 to 4, and a substitution position of a substituent is one of 4-position or 4′-position.

3. An ink jet ink obtained by the method for producing an ink jet ink according to claim 2.

4. An ink jet recording method comprising a step of ejecting an ink by ink jet method to conduct recording on a recording medium, wherein the ink is an ink jet ink according to claim 1.

5. An ink jet recording method comprising a step of ejecting an ink by ink jet method to conduct recording on a recording medium, wherein the ink is an ink jet ink according to claim 3.

6. An ink cartridge comprising an ink storage portion for storing ink, wherein the ink comprises an ink jet ink according to claim 1.

7. An ink cartridge comprising an ink storage portion for storing ink, wherein the ink comprises an ink jet ink according to claim 3.

8. An ink jet ink according to claim 1, wherein the ratio of the content (mass %) of the compound represented by the general formula (I) or a salt thereof (mass %) to the total content of the coloring material is from 9.0 mass % or more to 20.0 mass % or less.

9. An ink jet ink according to claim 3, wherein the ratio of the content (mass %) of the compound represented by the general formula (I) or a salt thereof (mass %) to the total content of the coloring material is from 9.0 mass % or more to 20.0 mass % or less.

10. An ink jet ink according to claim 1, wherein the compound having a copper phthalocyanine structure is C.I. Direct Blue 199.

11. An ink jet ink according to claim 3, wherein the compound having a copper phthalocyanine structure is C.I. Direct Blue 199.

12. An ink cartridge comprising an ink storage portion for storing ink, wherein the ink comprises an ink jet ink obtained by a method for producing an ink jet ink,
wherein the method for producing an ink jet ink comprises a step of filling the ink storage portion which stores an ink jet ink containing, as a coloring material, a compound represented by the following general formula (I) or a salt thereof, with an ink jet ink containing, as a coloring material, at least one selected from the group consisting of C.I. Acid Blue 9 and a compound having a copper phthalocyanine structure




 wherein l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 provided that l+m+n=3 to 4, and a substitution position of a substituent is one of 4-position and 4′-position.

13. A method for producing an ink cartridge comprising a step of filling an ink storage portion which stores an ink jet ink containing, as a coloring material, a compound represented by the following general formula (I) or a salt thereof, with an ink jet ink containing, as a coloring material, at least one selected from the group consisting of C.I. Acid
 Blue 9 and a compound having a copper phthalocyanine structure




 wherein l represents 0 to 2, m represents 1 to 3 and n represents 1 to 3 provided that l+m+n=3 to 4, and a substitution position of a substituent is one of 4-position and 4′-position.

14. An ink cartridge according to claim 12, wherein the compound having a copper phthalocyanine structure is C.I. Direct Blue 199.

15. A method for producing an ink cartridge according to claim 13, wherein the compound having a copper phthalocyanine structure is C.I. Direct Blue 199.