JP2003261813A - Method for producing pigment dispersion - Google Patents

Abstract

(57) [Summary] (Modifications) [Problem] To provide a method for adjusting the average particle size of a pigment by washing a filter membrane to increase the filtration efficiency of a pigment dispersion stock solution. A method for adjusting the average particle size of a pigment, comprising:
Dispersing the pigment in a solvent to prepare a pigment dispersion stock solution, and subjecting the pigment dispersion stock solution to cross-flow membrane filtration,
This is achieved by a method comprising washing a filter membrane with the turbulent pigment dispersion stock solution. The means for making the undiluted solution turbulent stirs the undiluted solution, explodes, hits the step plate,
Alternatively, the irradiation is performed by ultrasonic irradiation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pigment dispersion in which the average particle diameter of pigment is adjusted.

2. Description of the Related Art Inkjet recording methods involve ejecting small drops of ink
This is a printing method in which printing is performed by adhering it to a recording medium such as paper. The ink used in the ink jet recording method generally contains water as a main component, and further contains a coloring component and a wetting agent such as glycerin. As colorants used in ink jet recording inks, water-soluble dyes are often used because of the high saturation of colorants, the wide variety of colorants that can be used, and the ease with which they can be dissolved in water. There is.

On the other hand, in recent years, the use of pigments as colorants in ink jet recording inks has been studied for the purpose of improving light resistance and water resistance. Since the pigment is generally insoluble in water, it is prepared as an aqueous ink after mixing and dispersing the pigment with a resin called a dispersant. In order to disperse the pigment in the aqueous solvent, it is necessary to study the pigment type, particle size, resin type, dispersing means, and the like. Many dispersion methods and methods for producing inkjet recording inks have been proposed so far.

In the production of such a pigment-based ink, after the pigment, the dispersant and the water-soluble organic solvent are mixed with an appropriate disperser or mixer, filtration is carried out to remove coarse particles and unnecessary substances. It is common to For example, Japanese Patent Laid-Open No. 10-287836 proposes a method for producing an ink jet recording ink, which comprises adsorbing a resin on carbon black and then removing a part of the resin not adsorbed on carbon black by ultrafiltration. ing.

However, as far as the inventors of the present invention know, the average particle size of the pigment can be reduced by washing the solid component deposited on the surface of the filter membrane while removing the coarse pigment particles by membrane filtration of the pigment dispersion stock solution. A method capable of efficiently obtaining a pigment dispersion having a controlled diameter has not been disclosed yet.

[0006]

SUMMARY OF THE INVENTION The present inventors have recently attempted to protect the filter membrane and prolong its service life by washing the solid components of the pigment dispersion stock solution deposited on the surface of the filter membrane while performing cross-flow membrane filtration. The present inventors have found that it is possible to produce a pigment dispersion liquid in which the average particle diameter of the pigment is adjusted within a certain range with a high recovery rate by performing the filtration efficiently. Further, the present inventors have found that when the pigment dispersion liquid obtained by this production method is used for ink, an image excellent in ejection stability and color reproducibility can be realized. The present invention is based on these findings.

Therefore, according to the present invention, it is possible to efficiently carry out cross-flow membrane filtration by protecting the filter membrane and prolonging its service life. As a result, the pigment dispersion liquid having an adjusted average particle diameter has a high recovery rate. It is an object of the present invention to provide a method for producing a pigment dispersion liquid, which can be obtained by

Therefore, according to the first aspect of the present invention, there is provided a method for producing a pigment dispersion in which the average particle diameter of the pigment is adjusted. This method comprises dispersing the pigment in a solvent to prepare a pigment dispersion stock solution. And subjecting the stock solution to cross-flow membrane filtration,
Collecting the liquid that has permeated through the filter membrane or the liquid that has not permeated through the filter membrane as a pigment dispersion, and washing the solid component of the stock solution deposited on the surface of the filter membrane while performing cross-flow membrane filtration of the stock solution. It consists of

According to a second aspect of the present invention, there is provided a method for producing a pigment dispersion liquid in which the average particle size of the pigment is adjusted. This method comprises dispersing the pigment in a solvent to prepare a pigment dispersion stock solution. And then subjecting the stock solution to the first stage cross-flow membrane filtration,
The liquid that has permeated the filter membrane is recovered, the permeated liquid is subjected to a second-stage crossflow membrane filtration, and the liquid that has not permeated the filter membrane is recovered as a pigment dispersion liquid, and the first-stage crossflow membrane is recovered. In filtration, the solid solution of the stock solution deposited on the surface of the filter membrane is washed while cross-flow membrane filtering the stock solution, or in the second step cross-flow membrane filtration, the permeate is cross-flow membrane filtered. Cleaning the solid components of the permeate deposited on the surface of the filter membrane, wherein the average pore size of the filter membrane of the first-stage crossflow membrane filtration is the same as that of the second-stage crossflow membrane filtration. It is larger than the average pore size of the filtration membrane.

According to a third aspect of the present invention, there is provided a method for producing a pigment dispersion liquid in which the average particle diameter of the pigment is adjusted. This method comprises dispersing the pigment in a solvent to prepare a pigment dispersion stock solution. And then subjecting the stock solution to the first stage cross-flow membrane filtration,
The liquid that did not pass through the filter membrane was recovered, the impermeable liquid was subjected to a second-stage crossflow membrane filtration, and the liquid that passed through the filter membrane was recovered as a pigment dispersion liquid, and the first-stage crossflow was performed. In the membrane filtration, the solid component of the stock solution deposited on the surface of the filter membrane is washed while the stock solution is cross-flow membrane filtered, or the impermeable liquid is cross-flow membrane filtered in the second-stage cross-flow membrane filtration. While cleaning the solid components of the impervious liquid deposited on the surface of the filter membrane, where:
The average pore size of the first stage cross-flow membrane filtration membrane is
It is smaller than the average pore diameter of the filter membrane of the stage cross-flow membrane filtration.

[0011]

Cross Flow Membrane Filtration The method according to aspects of the present invention utilizes cross flow membrane filtration. Here, the "cross flow" refers to an operation in which the stock solution is allowed to flow in the axial direction of the filter membrane and the filtrate is moved across the filter membrane in the membrane filtration. “Membrane filtration” refers to an operation of bringing a stock solution into contact with a filter membrane, preferably while applying pressure, to separate a component that permeates through the filter membrane and a component that does not permeate through the filter membrane. Specific examples of membrane filtration include ultrafiltration, microfiltration, osmosis, reverse osmosis, dialysis, etc. In the present invention, ultrafiltration and microfiltration are preferred.

Examples of the filter membrane that can be used in the present invention include polymer membranes and ceramic membranes. Specific examples of the polymer film include cellulose, nitrocellulose, polyvinyl alcohol, vinyl chloride, nylon, polyester, polyethylene, polysulfone, and polyether sulfone. A specific example of the ceramic membrane is an alumina porous filter membrane. The form of the filter membrane can be appropriately determined in consideration of usage conditions, and for example, tubular, hollow, flat,
Examples thereof include hollow fibers. In the present invention, a commercially available filter membrane can be used, and specific examples thereof include a Filton ultrafiltration system “Centramate” and the like (manufactured by Pall Ltd.), an ultrafiltration system “Minitan” (Millipore). Manufactured by the company).

First Aspect of the Present Invention A first aspect of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 (A) shows a cross-flow membrane filtration device 1. FIG. 1B is an enlarged view of the membrane filtration unit of the crossflow membrane filtration device 1.

In the apparatus 1 shown in FIG. 1 (A), a pigment dispersion stock solution (hereinafter referred to as "stock solution") is introduced from a stock solution reservoir 2 into a stock solution introducing device 4 (which is provided with a turbulent flow generating means) by a pressure pump 14. To do. The stock solution introducing device 4 continuously or intermittently makes the stock solution into a turbulent flow by the turbulent flow generating means, and introduces the turbulent stock solution into the filter membrane 9 of the filtration pipe 5.

Subsequently, in the inside of the filter membrane 9 in the cross-flow membrane filtration shown in FIG. 1 (B), the stock solution introduced in the direction of the arrow 6 is pressed in the direction across the filter membrane 9. As a result,
The stock solution containing the pigment particles 8 smaller than the average pore diameter of the filter membrane 9 permeates the filter membrane 9 and passes through the discharge port 10 as a permeate to form a liquid reservoir 11
Stored in. Pigment particles 7 larger than the average pore size of the filter membrane 9
The stock solution containing is not permeated through the filter membrane 9 and remains in the filter membrane 9 as an impermeable liquid. According to the first aspect of the present invention, the desired pigment dispersion is either the liquid stored in the liquid reservoir 11 or the liquid remaining in the filter membrane of the cross flow membrane filtration.

In the present invention, while the stock solution is being subjected to cross-flow membrane filtration, the filter solution 9 for cross-flow membrane filtration is washed with the stock solution which has been turbulent in the stock solution introducing device 4. Specifically, as shown in FIG. 1 (B), the turbulent undiluted solution is filtered through the filtration membrane 9
When introduced into the inside, this stock solution imparts turbulent flow in the direction of arrow 12 to remove the solid component 3 of the stock solution deposited on the surface of the filter membrane 9 from the surface of the filter membrane 9 or the solid component 3 of the deposited stock solution. It prevents the filter membrane 9 from adhering to the surface.

The turbulent flow generating means in the stock solution introducing device 4 will be described with reference to FIG. FIG. 2 is an enlarged view of the stock solution introducing device 4 including the turbulent flow generating means. FIG. 2 (A)-
The turbulent flow generating means shown in (D) is preferable in the embodiment of the present invention. The apparatus shown in FIG. 2 (A) has a stirring means, and this stirring means stirs the undiluted solution into a turbulent flow. The apparatus shown in FIG. 2 (B) has an explosive means, and the explosive means explodes the undiluted solution into a turbulent flow.
The device shown in FIG. 2C has a step plate, and the stock solution is applied to the step plate to create a turbulent flow. The apparatus shown in FIG. 2 (D) has an ultrasonic wave generating means, and makes the turbulent flow of the stock solution by the ultrasonic waves emitted from the ultrasonic wave generating means. FIG. 2 (A)-
In (D), a stock solution is introduced from the right side of each figure, and this stock solution is made turbulent by each turbulent flow generating means, and the turbulent stock solution is sent from the left side of each figure into the filtration membrane 9 of the cross-flow membrane filtration. .

As described above, according to the embodiment of the present invention, the filter membrane is washed while performing the cross-flow membrane filtration to effectively prevent the solid components such as the pigment and the dispersant from being deposited or attached to the filter membrane. You can do it. As a result, it is possible to prevent clogging and damage of the filter membrane, protect the filter membrane, and prolong its life. Further, cross-flow membrane filtration can be efficiently performed, and a desired pigment dispersion liquid can be obtained.

According to a preferred embodiment of the present invention, the washing of the filter membrane is preferably carried out continuously or intermittently. In the case of intermittent washing, the time and the number of times may be appropriately determined according to the type and amount of the pigment, pigment dispersion or ink composition to be filtered. According to a preferred embodiment of the present invention, in the case of intermittent cleaning, an apparatus having a program installed in which a sensor is attached to a filter membrane of cross-flow membrane filtration, and washing is performed when solid component deposition is sensed on the surface of the filter membrane. Preferably by

In the first embodiment of the present invention, the average pore size of the filter membrane for cross-flow membrane filtration may be appropriately determined in consideration of the average particle size of the desired pigment, but is in the range of about 1 nm to 1 μm. , Preferably about 0.01 to 1 μm. By performing membrane filtration using this filtration membrane, a pigment dispersion liquid in which the average particle diameter of the pigment is adjusted to be in the range of about 10 to 300 nm, preferably about 10 to 200 nm can be obtained. The time, pressure and the like for performing the cross-flow membrane filtration may be appropriately determined in consideration of the particle size of the pigment to be filtered, the cohesiveness and the like.

Second Aspect of the Present Invention A second aspect of the present invention will be described with reference to FIGS. 3, 4 and 5. FIG. 3 shows the first-stage crossflow membrane filtration device 2
1 shows a filtration device in which 1 and a second stage cross-flow membrane filtration device 41 are combined. In the first-stage cross-flow membrane filtration device 21 shown in FIG. 3, a pigment dispersion stock solution (hereinafter referred to as “stock solution”) from a stock solution reservoir 22 by a pressure pump 34 is a stock solution introduction device 24 (which is provided with turbulent flow generation means). To introduce. The stock solution introducing device 24 continuously or intermittently makes the stock solution into a turbulent flow by the turbulent flow generating means, and introduces the turbulent stock solution into the filter membrane 23 of the filtration pipe 25.

Subsequently, the stock solution introduced in the direction of arrow 26 is pressurized in the direction crossing the filter membrane 23 inside the filter membrane 23 in the first-stage cross-flow membrane filtration shown in FIG. As a result, the stock solution containing the pigment particles 27 and 28 smaller than the average pore size of the filter membrane 23 passes through the filter membrane 23 and is stored as a permeate in the liquid reservoir 31 through the outlet 30. Then, the permeated liquid is sent from the liquid reservoir 31 to the raw liquid reservoir 42 of the second-stage cross-flow membrane filtration device 41 shown in the lower part of FIG. Filter membrane 2
The stock solution containing the pigment particles 29 having an average pore size larger than 3 does not pass through the filter membrane 23 and remains in the filter membrane 23 as an impermeable liquid.

In the present invention, while the undiluted solution is being subjected to the first-stage cross-flow membrane filtration, the filter membrane 23 for cross-flow membrane filtration is washed with the pigment-dispersed undiluted solution turbulent in the undiluted solution introduction device 24. Specifically, as shown in FIG. 4, when the turbulent stock solution is introduced into the filter membrane 23, the stock solution flows in the direction of the arrow 32 to filter the solid component 33 of the stock solution deposited on the surface of the filter membrane 23. The solid component 33 of the stock solution removed or deposited from the surface of the membrane 23 is prevented from adhering to the surface of the filtration membrane 23.

Next, in the second-stage cross-flow membrane filtration device 41 shown in the lower part of FIG. 3, the stock solution (which is the liquid that has passed through the first-stage cross-flow filter membrane) is discharged from the stock solution reservoir 42 by the pressure pump 54. To the stock solution introducing device 44 (which is provided with a turbulent flow generating means). The stock solution introduction device 44 continuously or intermittently makes the stock solution into a turbulent flow by the turbulent flow generating means, and introduces the turbulent stock solution into the filter membrane 49 of the filtration pipe 45.

Subsequently, inside the filter membrane in the second-stage cross-flow membrane filtration shown in FIG. 5, the stock solution introduced in the direction of arrow 6 is pressurized in the direction crossing the filter membrane 49. As a result, the stock solution containing the pigment particles 28 smaller than the average pore size of the filter membrane 49 passes through the filter membrane 49, passes through the outlet 50, and is stored in the liquid reservoir 51 and discharged. On the other hand, the pigment particles 28
When it is confirmed that there is no stock solution containing the above, the second-stage crossflow filtration device 41 is stopped, and the stock solution containing the pigment particles 27 existing in the circulation path of the filter membrane 49 is recovered as a desired pigment dispersion liquid. To do.

In the present invention, while the stock solution is being subjected to the second-stage cross-flow membrane filtration, the filter solution 49 for cross-flow membrane filtration is washed with the stock solution which has been turbulent in the stock solution introducing device 44. Specifically, as shown in FIG. 5, when the turbulent stock solution is introduced into the filter membrane 49, the stock solution flows in the direction of the arrow 47 and the solid component 48 of the stock solution deposited on the surface of the filter membrane 49 is filtered. It prevents the solid component 48 of the stock solution that is removed from or deposited on the surface of the membrane 49 from adhering to the surface of the filtration membrane 49.
In the second aspect of the present invention, the filter membrane washing of the first-stage crossflow membrane filtration and the filter membrane washing of the first-stage crossflow membrane filtration may be the same as those of the first aspect of the present invention. .

In the second aspect of the present invention, the average pore diameter of the filter membrane for cross-flow membrane filtration can be appropriately determined in conformity with the average particle diameter of the pigment to be adjusted. In the second aspect of the present invention, the average pore size of the filter membrane of the first-stage cross-flow membrane filtration is
This is the case when it is larger than the average pore diameter of the filter membrane in the second-stage cross-flow membrane filtration. In this case, the average pore size of the filter membrane in the first-stage cross-flow membrane filtration is in the range of about 0.05 to 1 μm, preferably in the range of about 0.2 to 1 μm The average pore size of the filter membrane is 0.001
Range of about 0.1 μm, preferably 0.01 to 0.1 μm
The range is about m. By carrying out the first-stage and second-stage cross-flow membrane filtration using such a filtration membrane, the average particle size of the pigment is adjusted to a range of about 10 to 300 nm, preferably about 10 to 200 nm. It is possible to obtain a pigment dispersion.

Third Aspect of the Present Invention In a third aspect of the present invention, the second-stage cross-flow membrane filtration device 41 shown in the lower part of FIG. 3 becomes a first-stage cross-flow membrane filtration device. The first-stage crossflow membrane filtration 21 shown in the upper part becomes a second-stage crossflow membrane filtration device,
Prepare the desired pigment dispersion. Therefore, in the third aspect of the present invention, only the first-stage crossflow membrane filtration and the second-stage crossflow membrane filtration are replaced in the second aspect of the present invention, and other than that, the third aspect of the present invention is used. It may be similar to the second embodiment.

Preparation of Pigment Dispersion Stock Solution The pigment dispersion stock solution is prepared by mixing and dispersing a pigment and a solvent. As a method for mixing and dispersing the pigment and the solvent, a conventional means can be used, and specific examples thereof include a dispersing machine / mixing machine (for example, ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill). , An ultrasonic homogenizer, a jet mill, an Ong mill, etc.).

A ) Pigment The pigment is not particularly limited, and both inorganic pigments and organic pigments can be used. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnest method or a thermal method can be used. As the organic pigment, azo pigments (azo lake, insoluble azo pigment,
Condensed azo pigments, chelate azo pigments and the like), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments,
A dioxazine pigment, a thioindigo pigment, an isoindolinone pigment, a quinofuraron pigment, etc.), a dye chelate (for example, a basic dye type chelate, an acid dye type chelate, etc.), a nitro pigment, a nitroso pigment, aniline black and the like can be used.

The carbon black used as the black ink is No. 2300, No. 900, MCF88, No. 3 manufactured by Mitsubishi Chemical.
3, No. 40, No. 45, No. 52, MA7, MA8, MA100, No2200B etc.
Columbia Raven5750, Raven5250, Raven5000, Rav
en3500, Raven1255, Raven700, etc. are Re made by Cabot
gal 400R, Regal 330R, Regal 660R, Mogul L, Monarch 70
0, Monarch 800, Monarch 880, Monarch 900, Monarch
1000, Monarch 1100, Monarch 1300, Monarch 1400 etc. are Color Black FW1, Color BlackFW2, manufactured by Degussa.
Color Black FW2V, Color Black FW18, Color Black F
W200, Color BlackS150, Color Black S160, Color Bla
ck S170, Printex 35, Printex U, Printex V, Printe
x 140U, Special Black 6, Special Black 5, Special
Black 4A, Special Black 4 etc. can be used.

The pigments used in the yellow ink include CIPigment Yellow 1, CIPigment Yellow 2,
CIPigment Yellow 3, CIPigment Yellow 12, CIP
igmentYellow 13, CIPigment Yellow 14C, CIPigme
nt Yellow 16,, CIPigment Yellow 17, CIPigment Y
ellow 73, CIPigment Yellow 74, CIPigment Yello
w 75, CIPigment Yellow 83, CIPigment Yellow 9
3, CIPigment Yellow95, CIPigment Yellow97, C.
I.Pigment Yellow 98, CIPigment Yellow 109, CIP
igment Yellow 110, CIPigment Yellow114, CIPigm
ent Yellow128, CIPigment Yellow129, CIPigment
Yellow138, CIPigment Yellow150, CIPigment Yel
low151, CIPigment Yellow154, CIPigment Yellow1
55, CIPigment Yellow180, CIPigment Yellow185 and the like.

As the pigment used in the magenta ink, CIPigment Red 5, CIPigment Red 7, CI
Pigment Red 12, CIPigment Red 48 (Ca), CIPigmen
t Red 48 (Mn), CIPigment Red 57 (Ca), CIPigment
Red 57: 1, CIPigment Red 112, CIPigment Red 122,
CIPigment Red 123, CIPigment Red 168, CIPig
ment Red 184, CIPigment Red 202 and the like.

Further, as the pigment used for the cyan ink, CIPigment Blue 1, CIPigment Blue 2, C.I.
I.Pigment Blue 3, CIPigment Blue 15: 3, CIPigme
nt Blue 15:34, CIPigment Blue 16, CIPigment Bl
ue 22, CIPigment Blue 60, CIVat Blue 4, CIV
at Blue 60.

B) Solvent The pigment dispersion stock solution is prepared by dispersing the pigment in a solvent. Solvents that can be used in the present invention include polymer dispersants, surfactants,
Alternatively, water, and a combination thereof may be used. If necessary, a water-soluble organic solvent added to the ink composition described below and other components may be further added. According to a preferred embodiment of the present invention, it is preferable to disperse a pigment together with a polymer dispersant or a surfactant to prepare a pigment dispersion stock solution.

1) Polymer Dispersant As a preferred example of the polymer dispersant, a natural polymer can be mentioned, and specific examples thereof include proteins such as glue, gelatin, casein and albumin; natural gums such as gum arabic and tragacanth. Rubbers; glucosides such as sabonine; alginic acid and alginic acid derivatives such as propylene glycol alginate, triethanolamine alginate and ammonium alginate; cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and ethyl hydroxy cellulose. Furthermore, synthetic polymers are mentioned as preferred examples of the polymer dispersant, and polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, potassium acrylate-acrylonitrile copolymers, vinyl acetate. -Acrylic ester copolymers, acrylic resins such as acrylic acid-acrylic ester copolymers; styrene-
Acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic Styrene-acrylic resin such as acid ester copolymer; styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, and vinyl acetate -Vinyl acetate-based copolymers such as ethylene copolymers, vinyl acetate-fatty acid vinyl ethylene copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers Included are coalesce and salts thereof. Among these, a copolymer of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and a polymer composed of a monomer having both a hydrophobic group and a hydrophilic group in the molecular structure are preferable.

2) Surfactant Specific examples of the surfactant include anionic surfactants (eg, sodium dodecylbenzenesulfonate, sodium laurate, ammonium salt of polyoxyethylene alkyl ether sulfate, etc.), nonionic surfactants. Agents (eg, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, etc.), amphoteric surfactant (eg, , N, N-dimethyl-N
-Alkyl-N-carboxymethylammonium betaine, N, N-dialkylaminoalkylenecarboxylate, N, N, N-trialkyl-N-sulfoalkyleneammonium betaine, N, N-dialkyl-N, N-
Bispolyoxyethylene ammonium sulfate betaine, 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine) and the like. These may be used alone or in combination of two or more.

According to a preferred embodiment of the present invention, it is preferable to further contain a glycol ether and / or an acetylene glycol surfactant. Specific examples of glycol ethers used in the present invention include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n- Propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n- Butyl ether, diethylene glycol mono-t- Chirueteru, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether,
Propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, di Propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-
Propyl ether and the like can be used, and these can be used alone or as a mixture of two or more kinds.

In the present invention, it is preferable to contain an acetylene glycol-based surfactant. Specific preferred examples of the acetylene glycol-based surfactant used in the present invention include compounds represented by the following formula (I).

[Chemical 1] [In the above formula, 0 ≦ m + n ≦ 50, and R ¹ , R ² , R
³ and R ⁴ are each independently an alkyl group (preferably an alkyl group having 6 or less carbon atoms)]

Among the compounds represented by the above formula (I), 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne is particularly preferable. -3,6-diol, 3,5-dimethyl-1-hexyne-3-ol and the like. It is also possible to use a commercially available product as the acetylene glycol-based surfactant represented by the above formula (I), and specific examples thereof include Surfynol 104, 82, 465, 485, or TG.
(Both available from Air Products and Chemicals. Inc.), Olfine STG, Olfine E1010
(Both are available from Nissin Chemical Co., Ltd.).

Method of Manufacturing Ink Composition According to a preferred embodiment of the present invention, the pigment dispersion manufactured by the method of manufacturing the pigment dispersion according to the present invention is mixed with a water-soluble organic solvent, water and the like to prepare an ink composition. It can be a thing. This ink composition is preferable for use in an inkjet recording method.

According to another preferred embodiment of the present invention, there is provided a method for producing an ink composition containing a pigment, a dispersant, and a water-soluble organic solvent.

Therefore, according to the fourth aspect of the present invention, there is provided a method for producing an ink composition containing a pigment, a dispersant, and a water-soluble organic solvent.
A pigment dispersion stock solution is prepared by dispersing the pigment in a solvent, the stock solution is subjected to cross-flow membrane filtration, and a solution that has passed through the filter membrane or a solution that has not passed through the filter membrane is recovered as a pigment dispersion solution. The method comprises washing the solid component of the stock solution deposited on the surface of the filter membrane while performing cross-flow membrane filtration of the stock solution.

A fourth aspect of the present invention is that the pigment dispersion stock solution according to the first aspect of the present invention becomes an ink stock solution,
Other than that, it may be the same as the first aspect of the present invention.

According to a fifth aspect of the present invention, there is provided a method for producing an ink composition containing a pigment, a dispersant, and a water-soluble organic solvent. And a water-soluble organic solvent are prepared, the stock solution is subjected to a cross-flow membrane filtration of the first stage, the liquid that has permeated the filter membrane is recovered, and the permeated liquid of the second stage is collected. A liquid that did not pass through the filter membrane was subjected to cross-flow membrane filtration, and was collected as an ink composition. In the first-stage cross-flow membrane filtration, the stock solution was deposited on the filter membrane surface while performing cross-flow membrane filtration. Washed the solid components of the stock solution, or
The step of cross-flow membrane filtration comprises washing the permeate with cross-flow membrane filtration while washing solid components of the permeate deposited on the surface of the filter membrane, wherein the first-stage cross-flow membrane is provided. The average pore diameter of the filtration membrane for filtration is larger than the average pore diameter of the filtration membrane for the second stage cross-flow membrane filtration.

A fifth aspect of the present invention is that the pigment dispersion stock solution according to the second aspect of the present invention becomes an ink stock solution,
Other than that, it may be the same as the second aspect of the present invention.

According to a sixth aspect of the present invention, there is provided a method for producing an ink composition containing a pigment, a dispersant, and a water-soluble organic solvent. And a water-soluble organic solvent, an ink stock solution is prepared, and the stock solution is subjected to a first-stage cross-flow membrane filtration, and a solution that has not permeated through the filter membrane is recovered. The solution that has been subjected to a two-stage cross-flow membrane filtration is recovered as an ink composition, and in the first-stage cross-flow membrane filtration, the stock solution is applied to the surface of the filter membrane while performing cross-flow membrane filtration. Washing the solid component of the stock solution deposited, or washing the solid component of the impermeable liquid deposited on the surface of the filter membrane while cross-flow membrane filtering the impermeable liquid in the second-stage cross-flow membrane filtration. Comprising: where the cross flow of the first stage The average pore diameter of the filtration of the filtration membrane is what smaller than the average pore diameter of the filtration membrane of a cross flow membrane filtration of the second stage.

A sixth aspect of the present invention is that the pigment dispersion stock solution according to the third aspect of the present invention becomes an ink stock solution.
Other than that, it may be the same as the third aspect of the present invention.

A ) Preparation of Ink Stock Solution In the method for producing an ink composition according to the present invention, the ink stock solution containing a pigment, a dispersant, and a water-soluble organic solvent is prepared by using the above-mentioned pigment dispersion stock solution. It may be similar to preparation. Therefore, the pigment and the dispersant (polymer dispersant, surfactant) may also be the same as those described in the preparation of the dispersion stock solution of the pigment.

In the present invention, the content of the pigment is in the range of about 0.1 to 10% by weight, preferably in the range of about 1 to 5% by weight, based on the total amount of the ink composition. The content of the dispersant is 0.01 to 1.5% by weight based on the total amount of the pigment component.
The range is about 0.1 to 1% by weight.

1) Water-Soluble Organic Solvent The water-soluble organic medium preferably includes a wetting agent made of a high boiling point organic solvent. Preferable examples of the high boiling point organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin and triglyceride. Polyhydric alcohols such as methylolethane and trimethylolpropane; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether,
Alkyl ethers of polyhydric alcohols such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether; 2
-Pyrrolidone, N-methyl-2-pyrrolidone, 1,3-
Examples include dimethyl-2-imidazolidinone and triethanolamine.

Among these, it is preferable to use a water-soluble organic solvent having a boiling point of 180 ° C. or higher. Use of a water-soluble organic solvent having a boiling point of 180 ° C. or higher brings about water retention and wettability of the ink composition. As a result, even when the ink composition is stored for a long period of time, there is no aggregation of the pigment or increase in viscosity, and excellent storage stability can be realized. Further, it is possible to realize an ink composition that maintains fluidity and redispersibility for a long time even when left in an open state (a state in which it is exposed to air at room temperature). Further, in the inkjet recording method, nozzle clogging does not occur during printing or upon restarting after printing is interrupted, and high ejection stability can be obtained.

Examples of the water-soluble organic solvent having a boiling point of 180 ° C. or higher include ethylene glycol (boiling point: 197 ° C .; hereinafter in brackets indicate boiling point), propylene glycol (187
C.), diethylene glycol (245.degree. C.), pentamethylene glycol (242.degree. C.), trimethylene glycol (214.degree. C.), 2-butene-1,4-diol (235.
C.), 2-ethyl-1,3-hexanediol (243
C.), 2-methyl-2,4-pentanediol (197
C), N-methyl-2-pyrrolidone (202 C), 1,
3-Dimethyl-2-imidazolidinone (257-260
℃), 2-pyrrolidone (245 ℃), glycerin (29
0 ° C.), tripropylene glycol monomethyl ether (243 ° C.), dipropylene glycol monoethyl glycol (198 ° C.), dipropylene glycol monomethyl ether (190 ° C.), dipropylene glycol (2
32 ° C), triethylene glycol monomethyl ether (249 ° C), tetraethylene glycol (327
C.), triethylene glycol (288.degree. C.), diethylene glycol monobutyl ether (230.degree. C.), diethylene glycol monoethyl ether (202.degree. C.), diethylene glycol monomethyl ether (194.degree. C.). Those having a boiling point of 200 ° C. or higher are preferable.
These water-soluble organic solvents can be used alone or in combination of two or more.

The content of the high boiling point organic solvent is preferably about 0.01 to 10% by weight, more preferably about 0.1 to 5% by weight, based on the total amount of the ink composition.

Further, as the water-soluble organic solvent, a tertiary amine can be mentioned. Addition of a tertiary amine provides wetting to the ink composition. Specific examples of the tertiary amine include trimethylamine, triethylamine, triethanolamine,
Examples thereof include dimethylethanolamine, diethylethanolamine, triisopropenolamine and butyldiethanolamine. These may be used alone or as a mixture. The amount of the tertiary amine added is about 0.1 to 10% by weight, and more preferably about 0.5 to 5% by weight, based on the total amount of the ink composition.

2) Water and Other Components In the method for producing an ink composition according to the present invention, water and other components may be further added in addition to the components described above to produce the ink composition.

Specific examples of the other components include alkali hydroxide, examples of which include potassium hydroxide and
Sodium hydroxide and lithium hydroxide are added in an amount of about 0.01 to 5% by weight, preferably about 0.05 to 3% by weight, based on the total amount of the ink composition.

Other components include surfactants, and specific examples thereof include anionic surfactants (for example, sodium dodecylbenzenesulfonate, sodium laurate, ammonium salt of polyoxyethylene alkyl ether sulfate, etc.), Nonionic surfactant (eg, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, etc.), amphoteric interface Activator (eg, N, N-dimethyl-N-alkyl-N-carboxymethylammonium betaine, N, N
-Dialkylaminoalkylenecarboxylic acid salt, N, N,
N-trialkyl-N-sulfoalkylene ammonium betaine, N, N-dialkyl-N, N-bispolyoxyethylene ammonium sulfate ester betaine, 2-alkyl-1-carboxymethyl-1-hydroxyethyl imidazolinium betaine), etc. Is mentioned. These may be used alone or in combination of two or more.

The amount of the surfactant added is about 0.01 to 10% by weight, preferably about 0.1 to 5% by weight, based on the total amount of the ink composition.

According to a preferred embodiment of the present invention, it is preferable that a glycol ether and / or an acetylene glycol-based surfactant be further added to produce an ink composition.

Glycol ethers are also used as the above water-soluble organic solvent, and specific examples thereof include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate. , Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether,
Ethylene glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-
Methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether,
Propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, di Propylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether and the like can be mentioned, and they can be used alone or as a mixture of two or more kinds.

According to a preferred embodiment of the present invention, it is preferably produced by adding an acetylene glycol type surfactant. By adding an acetylene glycol-based surfactant, the permeability of the ink composition into a recording medium can be increased, and printing with less bleeding can be expected on various recording media. Specific preferred examples of the acetylene glycol surfactant include compounds represented by the following formula (I).

[Chemical 2] [In the above formula, 0 ≦ m + n ≦ 50, and R ¹ , R ² , R
³ and R ⁴ are each independently an alkyl group (preferably an alkyl group having 6 or less carbon atoms)]

Among the compounds represented by the above formula (I), 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne is particularly preferable. -3,6-diol, 3,5-dimethyl-1-hexyne-3-ol and the like. It is also possible to use a commercially available product as the acetylene glycol-based surfactant represented by the above formula (I), and specific examples thereof include Surfynol 104, 82, 465, 485, or TG.
(Both available from Air Products and Chemicals. Inc.), Olfine STG, Olfine E1010
(Both are available from Nisshin Chemical Co., Ltd.). The amount of the surfactant added is about 0.01 to 10% by weight based on the total amount of the ink composition, and more preferably 0.1.
It is preferably about 1 to 5% by weight.

In the present invention, it is preferable to produce an ink composition by adding a sugar or a sugar derivative. Addition of sugar or sugar derivatives provides water retention to the ink composition. Particularly, remarkable water retention can be imparted by using it in combination with a salt of hyaluronic acid or a derivative thereof.

Examples of sugars include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose and aldone. Acid, glucitol, (sorbit), maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like can be mentioned. Here, the term "polysaccharide" means a sugar in a broad sense, and is meant to include substances widely existing in nature such as alginic acid, α-cyclodextrin, and cellulose. Examples of derivatives of these sugars include reducing sugars [(for example, sugar alcohol (general formula HOCH ₂ (CHOH) _n
CH ₂ OH (where n is an integer of 2 to 5 is represented), oxidized sugar (eg, aldonic acid, uronic acid, etc.), amino acid, thiosugar and the like. Sugar alcohol is particularly preferable, and specific examples thereof include maltitol, sorbitol and the like. The addition amount of sugar or a sugar derivative is preferably about 0.1 to 40% by weight, and more preferably about 2.5 to 20% by weight, based on the total amount of the ink composition.

In the present invention, glycerin is preferably added to produce an ink composition. Addition of glycerin effectively prevents the ink composition from drying on the front surface of the nozzle of the recording head and prevents the nozzle from clogging. The amount of glycerin added is 5 to 40% by weight based on the total amount of the ink composition.
It is about 10 to 20% by weight, and preferably about 10 to 20% by weight.

In the present invention, a nozzle clogging preventive agent, an antiseptic agent, an antioxidant agent, a conductivity adjusting agent, a pH adjusting agent,
The ink composition can be produced by adding a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorbing agent and the like.

Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, and 2-
Pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate, 1,2-dibenzisothiazolin-3-one (ICI Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel TN), etc. I can give you.

[Brief description of drawings]

FIG. 1 (A) is a schematic view of a cross-flow membrane filtration device 1. FIG. 1B is an enlarged view of the membrane filtration unit of the crossflow membrane filtration device 1.

2 (A) to 2 (D) are enlarged views of a stock solution introducing device 4 equipped with a turbulent flow generating means.

FIG. 3 is a first-stage cross-flow membrane filtration device and a second
It is a schematic diagram of the membrane filtration device which consists of a cross-flow membrane filtration device of steps.

FIG. 4 is an enlarged view of a membrane filtration section of the first-stage crossflow membrane filtration device.

FIG. 5 is an enlarged view of a membrane filtration section of a second-stage crossflow membrane filtration device.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 FC02                 4J037 AA02 AA15 AA22 CA08 CB07                       CB10 CC01 CC13 CC15 CC16                       CC17 DD23 EE08 EE28 EE33                       EE43                 4J039 BE01 BE02 BE12 BE22 CA03                       DA02 GA24

Claims (24)

[Claims] 1. A method for producing a pigment dispersion liquid in which the average particle diameter of the pigment is adjusted, wherein the pigment is dispersed in a solvent to prepare a pigment dispersion stock solution, and the stock solution is subjected to cross-flow membrane filtration, Collecting a liquid that has permeated the filter membrane or a liquid that has not permeated the filter membrane as a pigment dispersion, and washing the solid component of the stock solution deposited on the surface of the filter membrane while cross-flow membrane filtering the stock solution. How to be 2. The method according to claim 1, wherein the cleaning is performed by making the stock solution turbulent and removing solid components of the stock solution accumulated by the turbulent flow from the surface of the filter membrane. 3. The method according to claim 2, wherein the means for making the undiluted solution into a turbulent flow is performed by agitating the undiluted solution, exploding, hitting a step plate, or irradiating with ultrasonic waves. 4. A method for producing a pigment dispersion liquid in which the average particle diameter of the pigment is adjusted, wherein the pigment is dispersed in a solvent to prepare a pigment dispersion stock solution, and the stock solution is subjected to first-stage cross-flow membrane filtration. The liquid permeated through the filter membrane was recovered, the permeated liquid was subjected to a second-stage cross-flow membrane filtration, and the liquid that did not permeate the filter membrane was recovered as a pigment dispersion liquid. In the cross-flow membrane filtration, the solid solution of the stock solution deposited on the surface of the filter membrane is washed while the stock solution is subjected to the cross-flow membrane filtration, or the permeate is cross-flowed in the second-stage cross-flow membrane filtration. Washing the solid component of the permeate deposited on the surface of the filtration membrane during membrane filtration, wherein the average pore size of the filtration membrane of the first stage cross-flow membrane filtration is the second stage It is larger than the average pore size of the filtration membrane of the flow membrane filtration, Law. 5. The rinsing process uses the stock solution or the permeate as a turbulent flow, and removes solid components of the stock solution deposited by the turbulent flow from the filter membrane surface of the first-stage cross-flow membrane filtration, or the turbulent flow. The method according to claim 4, which is carried out by removing the solid component of the permeate accumulated by flow from the filtration membrane surface of the second stage cross-flow membrane filtration. 6. The means for making the undiluted solution or the permeated liquid into a turbulent flow is performed by agitating the undiluted solution or the permeated solution, exploding, hitting a step plate, or irradiating ultrasonic waves. The method described in. 7. A method for producing a pigment dispersion liquid in which the average particle diameter of the pigment is adjusted, wherein the pigment is dispersed in a solvent to prepare a pigment dispersion stock solution, and the stock solution is subjected to a first-stage cross-flow membrane filtration. The liquid that did not pass through the filter membrane was recovered, the impermeable liquid was subjected to a second-stage cross-flow membrane filtration, and the liquid that passed through the filter membrane was recovered as a pigment dispersion liquid. In the cross-flow membrane filtration of the second stage, while washing the stock solution with the cross-flow membrane filtration, the solid components of the stock solution deposited on the surface of the filter membrane are washed, or in the second-stage cross-flow membrane filtration, the impermeable liquid is removed. Washing the solid component of the impervious liquid deposited on the surface of the filter membrane while performing cross-flow membrane filtration, wherein the average pore size of the filter membrane of the first-stage cross-flow membrane filtration is the second It is smaller than the average pore size of the filter membrane of the stage cross-flow membrane filtration. That, way. 8. The washing process uses the stock solution or the impermeable solution as a turbulent flow, and removes solid components of the stock solution deposited by the turbulent flow from the surface of the filter membrane of the first-stage cross-flow membrane filtration, or The method according to claim 7, which is carried out by removing the solid component of the retentate that is accumulated by turbulent flow from the filter membrane surface of the second stage cross-flow membrane filtration. 9. The means for making the undiluted liquid or the impermeable liquid into a turbulent flow is performed by stirring the undiluted liquid or the impermeable liquid, exploding the air, hitting the step plate, or irradiating ultrasonic waves. Item 8. The method according to Item 8. 10. The method according to claim 1, wherein the cleaning is performed continuously or intermittently. 11. An ink composition comprising the pigment dispersion produced by the method according to any one of claims 1 to 10. 12. The ink composition according to claim 11, which is used in an ink jet recording method. 13. A method for producing an ink composition containing a pigment, a dispersant, and a water-soluble organic solvent, which comprises an ink stock solution containing the pigment, a dispersant, and a water-soluble organic solvent. The prepared stock solution was subjected to cross-flow membrane filtration, and a solution that passed through the filter membrane or a solution that did not pass through the filter membrane was recovered as an ink composition. Cleaning the solid components of the stock solution deposited on the 14. The method according to claim 13, wherein the washing is performed by making the stock solution turbulent and removing solid components of the stock solution deposited by the turbulent flow from the surface of the filter membrane. 15. The method according to claim 14, wherein the means for making the undiluted solution into a turbulent flow is performed by agitating the undiluted solution, blasting it, hitting it on a step plate, or irradiating ultrasonic waves. 16. A method for producing an ink composition comprising a pigment, a dispersant and a water-soluble organic solvent, which comprises an ink stock solution comprising the pigment, a dispersant and a water-soluble organic solvent. The prepared solution was subjected to the first-stage cross-flow membrane filtration, the liquid that permeated through the filter membrane was recovered, and the permeated liquid was subjected to the second-stage cross-flow membrane filtration without passing through the filter membrane. Liquid is recovered as an ink composition, and in the first step cross-flow membrane filtration, the solid component of the stock solution deposited on the surface of the filter membrane is washed while cross-flow membrane filtering the stock solution, or the second step. The step of cross-flow membrane filtration comprises washing the permeate with a solid component of the permeate deposited on the surface of the filter membrane while performing cross-flow membrane filtration of the permeate. The average pore size of the filtration membrane is the second cross flow It is larger than the average pore size of the filtration filtration membrane, the method. 17. The washing method uses the stock solution or the permeate as a turbulent flow, and removes solid components of the stock solution deposited by the turbulent flow from the surface of the filter membrane of the first-stage cross-flow membrane filtration, or the turbulent flow. The method according to claim 16, which is carried out by removing the solid component of the permeate accumulated by flow from the filter membrane surface of the second-stage cross-flow membrane filtration. 18. A means for making the stock solution or the permeate into a turbulent flow, stirring the stock solution or the permeate and exploding,
The method according to claim 17, which is performed by applying a step plate or irradiating ultrasonic waves. 19. A method for producing an ink composition containing a pigment, a dispersant and a water-soluble organic solvent, which comprises an ink stock solution containing the pigment, a dispersant and a water-soluble organic solvent. The prepared solution was subjected to the first-stage cross-flow membrane filtration, the liquid that did not permeate the filter membrane was recovered, and the impermeable liquid was subjected to the second-stage cross-flow membrane filtration to remove the filter membrane. The permeated liquid is recovered as an ink composition, and in the first-stage crossflow membrane filtration, the solid component of the stock solution deposited on the surface of the filter membrane is washed while the stock solution is crossflow membrane filtered, or The two-stage cross-flow membrane filtration comprises washing the solid component of the impervious liquid deposited on the surface of the filter membrane while performing cross-flow membrane filtration on the impermeable liquid. The average pore size of the cross-flow membrane filtration membrane is the second stage cross It is smaller than the average pore diameter of the filtration membrane of low membrane filtration method. 20. In the washing, the stock solution or the impermeable solution is made to be a turbulent flow, and solid components of the stock solution deposited by the turbulent flow are removed from the surface of the filter membrane of the first-stage cross-flow membrane filtration, or 20. The method according to claim 19, which is carried out by removing the solid component of the retentate accumulated by turbulent flow from the filter membrane surface of the second stage cross-flow membrane filtration. 21. The means for making the undiluted solution or the impermeable liquid into a turbulent flow is performed by agitating the undiluted solution or the permeated solution, exploding, hitting a step plate, or irradiating ultrasonic waves. The method according to 20. 22. The method according to claim 13, wherein the cleaning is performed continuously or intermittently. 23. An ink composition produced by the method according to any one of claims 13 to 22. 24. The ink composition according to claim 23, which is used in an inkjet recording method.